Light-induced oxidation-reduction reactions of cytochromes in the green sulfur photosynthetic bacterium Prosthecochloris aesturarii. The light-induced oxidation-reduction reactions of cytochromes in intact cells, starved cells, and chlorobium vesicle fractions of the green sulfur photosynthetic bacterium Prosthecochloris aesturarii were studied under anaerobic conditions. On the basis of both kinetic and spectral properties, at least three cytochrome species were found to be involved in the light-induced oxidation-reduction reactions of intact cells. These cytochromes were designated according to the positions of alpha-band maxima as C555 (rapid and slow components) and C552 (intermediate). By comparing the light-minus-dark difference spectra with the reduced-minus-oxidized difference spectra of purified cytochromes of this organism, rapid component C555 and intermediate component C552 are suggested to correspond to the purified cytochromes c-555(550) and c-551.5, respectively. Although the identity of the slow-phase component is uncertain, one possibility is that the slow phase is due to the bound form of c-555(550). In substrate-depleted (starved) cells, only one cytochrome species, C555 remained in the reduced state in the dark and oxidized upon actinic illumination. This corresponds to the rapid C555 component in intact cells. In the case of chlorobium vesicle fractions, one cytochrome species having an alpha-band maximum at 554 nm was oxidized by actinic light. The effects of several inhibitors on the absorbance changes of intact cells were studied. Antimycin A decreased the rate of the dark reduction of rapid C555 component. The complex effects of CCCP (carbonyl cyanide m-chlorophenylhydrazone) on the oxidation-reduction reactions of cytochromes were interpreted as the results of inhibition of the electron donation to oxidized C552 and C555 (slow), and a shift of the dark steady-state redox levels of cytochromes. Based on these findings, it is suggested that the rapid C555 component is located in a cyclic electron transfer pathway. The other two cytochromes, C552 and C555 (slow), may be located in non-cyclic electron transfer pathways and receive electrons from exogenous substrates such as sodium sulfide. A tentative scheme for the electron transfer system in Prosthecochloris aestuarii is presented and its nature is discussed.


Flavodoxin: an allosteric inhibitor of AMP nucleosidase from Azotobacter vinelandii. Flavodoxin, which participates in nitrogen fixation, was found to be a potent allosteric inhibitor of AMP nucleosidase [EC 3.2.2.4] from Azotobacter vinelandii. It inhibited the enzyme by decreasing its affinity for ATP without affecting the maximum velocity. The inhibition constant for flavodoxin was estimated to be 10 muM, which is within the range of physiological concentration in the cells. The concentration of flavodoxin able to alter the activity in vitro suggests that this phenomenon could be of significance in the regulation of flavin biosynthesis in vivo. Flavin mononucleotide (FMN), a prosthetic group of flavodoxin, was also found to act as an allosteric inhibitor. Since no inhibitory action of apo-flavodoxin was observed, it was concluded that the FMN chromophore of the flavodoxin is responsible for the inhibition of the enzyme by this protein.


Metabolism of threo-beta-methylmalate by a soil bacterium. Studies on threo-beta-methylmalate metabolism in a soil bacterium of the genus Bacillus which can utilize threo-beta-methylmalate as a sole carbon source were carried out. When DL-threo-beta-methylmalate was incubated with a cell-free extract of the bacterium, citramalate was found to be formed. Similarly, formation of threo-beta-methylmalate from DL-citramalate was confirmed. These dicarbosylic acids were identified by gas chromatography-mass spectrometry. Examination of inducibility, substrate specificity, and cofactor requirement of the enzymes involved in the reactions showed the existence of two interconversion reactions between the threo-beta-methylmalate and citramalate. One was an interconversion reaction between L-threo-beta-methylmalate and L-citramalate via mesaconate and the other was an interconversion reaction between D-threo-beta-methylmalate and D-citramalate via citraconate. These reactions were both reversible and were catalyzed by distinct and inducible enzymes. It is suggested that the two reactions participate in the catabolism of threo-beta-methylmalate.


Changes in mitochondrial phosphorylative activity and adenylate energy charge of regenerating rabbit liver. The changes in the cellular concentrations of ATP, ADP, and AMP and in oxidative phosphorylation of mitochondria were investigated in the remaining liver of partially hepatectomized rabbits. The energy charge (defined as half of the average number of anhydride-bonded phosphate groups per adenosine moiety) of the liver remnant decreased from 0.866 to 0.767 (p less than 0.01) within 24 hr after hepatectomy, and then increased to a substantially higher level than normal within 7 days. On the other hand, the mitochondrial phosphyorylative activity increased rapidly to 170 per cent of the control within 12 hr and then retruned to normal within 7 days. The mitochondrial phosphorylative activity was inversely correlated with energy charge of the liver remnant (r = -0.75, p less less than 0.01). The maximal enhancement of mitochondrial phosphorylative activity was found in mitochondria obtained from the liver remnant with the lowest level of energy charge, suggesting a response of mitochondria in vivo involving enhanced biosynthetic ATP-utilizing reactions at an early stage of the regenerating process. The enhancement of phosphorylative activity was accompanied by a rise in the respiratory control ratio, P/O ratio and state 3 respiration. The adenylate kinase [EC 2.7.4.3] activity in the liver remnant increased to more than 160% of the control within 2 days after partial hepatectomy, while the pyruvate kinase [EC 2.7.1.40] activity decreased remarkably. However, the changes in the two enzyme activities did not correlate with those of mitochondrial phosphorylative activity or the energy charge of the liver remnant.


Zinc binding by glycosaminoglycans.

Zinc binding by glycosaminoglycans. Seven different standard GAGs were shown to bind various amounts of 65Zn by gel filtration on Sephadex G-25 at pH 4.0 and pH 7.0. "Molar" zinc-binding ratios, calculated on the basis of molar bound 65Zn per hexuronic acid and sulfate of each GAG, were significantly different for C4S, C6S, DS, HA, HS, at the two pHs; however, there was no difference for HP and KS. Moreover, while the binding ratios of C4S, C6S, and DS were higher, those of HA and HS were lower at pH 4.0 than at pH 7.0. The order of increasing zinc-binding ratios was (i) HS, KS, HA, C6S, C4S, DS, HP at pH 4.0 and (ii)  C6S, KS, C4S, DS, HS, HP, HA at pH 7.0.


Release of fatty acids from phosphatidylcholine by lecithin-cholesterol acyltransferase. Partially purified lecithin-cholesterol acyltransferase [EC 2.3.1.43] from human plasma released fatty acids from phosphatidylcholine. Heating, sulfhydryl reagents, Ca2+, EDTA, and sodium deoxycholate had similar effects on the lecithin-cholesterol acyltransferase and fatty acid releasing activities of the preparation. A specific cofactor protein for lecithin-cholesterol acyltransferase, apoA-1, also enhanced both activities. Release of fatty acid was due to enzymatic hydrolysis of the ester linkage at carbon-2 of phosphatidylcholine. It is suggested that the two activities are due to a single enzyme.


A potent polyamine analog, spermindiol.

A potent polyamine analog, spermindiol. The effects of spermine, putrescine, and spermindiol on different nucleases were investigated. A highly active spermine analog, spermindiol, was synthesized, which markedly enhanced DNA hydrolysis by staphylococcal nuclease and spleen DNase II [EC 3.1.4.6] and RNA degradation by staphylococcal nuclease and pancreatic RNase A [EC 3.1.4.22]. Spermindiol also increased the melting temperature of calf thymus DNA.


Regulatory protein of vascular smooth muscle. Preparations of native tropomyosin from the muscles of bovine aorta and carotid artery resensitized myosin B from either tissue. Neither preparation had any effect on desensitized myosin B from skeletal muscle but native tropomyosin from skeletal muscle could resensitize desensitized myosin B from vascular smooth muscles.


Transport of D-allose by isolated fat-cells: an effect of adenosine triphosphate on insulin stimulated transport. D-allose, a glucose analogue, is not metabolized by isolated fat-cells and its distribution space at equilibrium in the cells is the same as that of triated water. Uptake of allose is inhibited by glucose and 3-O-methylglucose, stimulated by insulin and virtually eliminated by cytochalasan B. Counter transport of allose out of fat-cells against a concentration gradient can be induced by exogenous glucose but not by pyruvate. It is concluded that allose is transported into fat-cells by the same carrier mediated transport system as glucose and that it is a suitable analogue with which to study the glucose transport system. Insulin stimulated allose transport, into or out of the cell, but not basal transport, is inhibited by a brief exposure of isolated fat-cells to exogenous ATP or ADP (but not AMP or AMP-PNP). The antilipolytic effect of insulin is not affected. The ATP inhibition is slowly reversible. It is suggested that ATP phosphorylates a membrane component and thereby blocks transmission of signal from the insulin receptor to the carrier system. Indirect evidence suggests that ATP does not alter the affinity of the insulin or glucose binding sites. Insulin decreases the Km of glucose metabolism of CO2 and lipid in isolated fat-cells and increases the Vmax. However,the hormone has no effect on the Ki of glucose as an inhibitor of allose transport. The glucose analogue, 3-O-methyl-glucose, also inhibits both glucose metabolism and allose transport. The Ki for both these processes is similar and is not affected by insulin. These results support the view that the effect of insulin on glucose transport is to raise the Vmax without a change in the Km. It appears further that sugar transport is not the major rate limiting step in metabolism at high glucose concentrations in the absence of insulin, or at most glucose concentrations in the presence of the hormone.


CANCERLINE: a new NLM/NCI data base.

CANCERLINE: a new NLM/NCI data base. This paper describes collaborative efforts between the National Cancer Institute (NCI) and the National Library of Medicine) (NLM) for the development of a new data base called CANCERLINE. The scope content, and future enhancements of this on-line file are discussed, as well as the plans for its use to disseminate cancer-related information via NLM's biomedical communications network.


Introducing and implementing on-line bibliographic retrieval services in a scientific research and development organization. The National Bureau of Standards Library recently implemented on-line bibliographic retrieval services. Methods are given to orient and aid users in availing themselves of the services. Results are presented, based on appraisal of the services by users: value to users; most used data bases; problems requiring search revision; reasons for unsatisfactory results; purposes for request and use of search results; impact on subsequent library use; and future searching requirements. On-line capability impacts on library financing as a whole and on the library role in the community are described.


[Surgical indications and results of thoracic sympathectomy]. Between the 1st of July 1971 and the 31st of December 1974, among 1,459 operations on vascular surgery, we carried out 77 thoracic sympathectomies in 46 patients. In most patients there was an oblitering angiopathie of digital type, stage II to IV, confirmed by angiography. Two patients had mixed type obstructions, two others had hyperhidrosis, one patient suffered from cleroderma, another had a thoracic outlet syndrome with digital arterial obstruction. In all cases, the transaxillary approach was that which caused the least complications and which permitted satisfactory exposure of the sympathetic nerve. The cosmetic results were good. The second and third thoracic ganglia were resected and the planes of cleavage marked with silver clips. In advanced stage III and stage IV, we noted 92 p. 100 improvements i.e. return to stages I or II. The operative mortality was nil. The most serious complication was a case of hemothorax which required later pulmonary decortication. We noted in two cases, a Horner's syndrome.


[Abnormalities of the 1st rib and their vascular effects. Apropos of 8 cases]. In this article, the authors report 8 cases of abnormal first rib, producing mainly arterial vascular disorders. The costal abnormalities, the clinical vascular disorders and the arteriographic signs are then reviewed. Treatment was then discussed and the methods of resection of the cervical rib are noted.


[Fractures of the spine in children without permanent neurological injuries]. Three cases of trauma of the spine are reported compared with dislocation of the cervical spine; these mixed lesions are especially rare. They usually produce various spinal disorders which result in irreversible paralysis. The young age of one of these children and the favourable course, shows the interest of emergency repair of the damage. Reduction of the dislocation followed by internal fixation, may lead to a favourable course.


[Perforation of gastroduodenal ulcers. Therapeutic trends. Apropos of 284 cases]. The authors analyse retrospectively 284 case records of perforation of gastric and duodenal ulcers treated between 1961 and 1972 and, from a study of the literature, the authors attempt to draw up prognostic factors which permit one to apply to this complication of ulcer disease, the most efficient short and long-term treatment.


A comparison of electron-capture GLC, electrolytic-conductivity GLC and UV-absorption HPLC for the analysis of some herbicides in foods. A comparison of gas chromatography with electron-capture or electrolytic-conductivity (nitrogen mode) detection, and high-pressure liquid chromatography (HPLC) with UV-absorption detection (254 nm) was carried out for the analysis of several herbicides in foods. Linuron, propanil, terbacil, benzoylprop-ethyl, and the fungicide DCNA in samples of cabbage, corn, potato, and wheat spiked at 2 and 0.2 ppm were examined. The pesticides were extracted with acetone, partitioned into petroleum ether-methylene chloride, and cleaned up on a 2% deactivated Florisil column before direct chromatographic analysis. Electron-capture gas-liquid chromatography (GLC) was most suitable for DCNA and benzoylprop-ethyl while UV-absorption HPLC was best for  terbacil analysis. Linuron and propanil gave similar results for both electron-capture GLC and HPLC. Electrolytic-conductivity GLC could detect all pesticides at the 0.2 ppm level and exhibited the least number of extraneous peaks in the chromatograms.


GC-MS analysis of fatty acids from flue-cured tobacco. Fatty acids obtained by saponification of a hexane-soluble  fraction of flue-cured tobacco were converted to their methyl esters. The esters were purified by TLC and identified by GC-MS. Qualitative and quantitative results are reported for acids of chain lengths C12-C34.


The use of sodium borate impregnated silica gel plates for the separation of 3-0-methyl catecholamines from their corresponding catecholamines. The use of sodium borate impregnated silica gel plates for the chromatographic separation of the catecholamines noradrenaline, adrenaline, and isoprenaline from their respective 3-0-methylated derivatives, normetanephrine, metanephrine, and methoxy-isoprenaline, is described. The parent catecholamines remain at the origin of the plates while the 3-0-methylated derivatives concentrate in discrete bands at the upper edge of the borate impregnated area (the "borate front").


Pyrolysis GLC identification of food and drug ingredients. II. Qualitative and quantitative analysis of penicillins and cephalosporins. Pyrolysis gas-liquid chromatography (PGLC) provided reproducible pyrograms for 14 penicillins and cephalosporins studied which permitted direct characterization and differentiation of the antibiotics in almost all cases. The quantitative application of the technique was explored using four of the antibiotics. Standard curves were constructed based on the height of the most intense (and symmetrical) peak in the pyrograms. Excellent linearity was obtained in the ranges studied, 10 nanograms - 100 micrograms. Further quantitative application of the method is discussed.


Attracting and training more chemical pathologists in the United Kingdom. I have attempted to define the function of the medical graduate in the clinical biochemistry laboratory and have examined data on recrutiment in the United Kingdom into clinical biochemistry. If trainee pathologists were encouraged to become proficient in both a branch of clinical medicine and in research techniques, the resulting chemical pathologists should be able to improve the consultative and investigative functions of the laboratory. To this end I have suggested some changes in the training regulations and in the role of the chemical pathologists.


Assessment of thyroid hormone assays.

Assessment of thyroid hormone assays. Four techniques for estimating serum T4 and three for estimating serum T3 have been investigated and found to be satisfactory in routine use. Normal ranges for each techniques have been established. Estimation of serum T3 by the commerical kits tested appears to have a high discriminant value in the diagnosis of hyperthyroidism, although the diagnostic definition used inevitably enhances the apparent sensitivity of these techniques. Estimation of serum T4 will identify the majority of patients with symptomatic hypothyroidism. The low sensitivity of T3 in the diagnosis of thyroid failure is confirmed.


Renal biopsy in the milk-alkali syndrome. In milk-alkali syndrome the degree of renal impairment varies greatly. Few reports have been published describing structural changes on renal biopsy. In three illustrative cases, impairment of renal function was related to morphological changes shown on percutaneous biopsy. Milk-alkali syndrome should be considered as a cause of renal dysfunction in patients with a long history of dyspensia.


Meningitis caused by an alkali-producing pseudomonad. The clinical and microbiological features of a case of meningitis, due to an alkali-producing pseudomonad which closely resembles Pseudomonas pseudoalcaligenes, are described. A respiratory infection and a course of antibiotic therapy before admission to hospital may have been predisposing factors to opportunistic infection by this normally saprophytic organism. The problems of identifying alkali-producing pseudomonads are discussed.


Citrobacter koseri meningitis in a special care baby unit. An outbreak of meningitis due to Citrobacter koseri in a special care baby unit is described. The organism showed a high capacity for spread among the babies on the unit and although the intestinal carriage rate was high, the clinical case:carrier ratio was low.


A modified rubella HI test using prestandardized reagents. A modified haemagglutination inhibition test for rubella antibodies using prestandardized freeze-dried reagents was compared to a "standard" method. Tests of 707 serum samples showed that the modified test was sensitive and reliable by both macrotitration and microtitration techniques. The minor disadvantages of some reduction in antibody level when rubella sera were tested within one week of the rash and of spontaneous sheep erythrocyte agglutination in 0-7% of sera were out-weighed by the increased speed of the new test and the fact that it was carried out at room temperature.


Incidence of sperm antibodies before and after vasectomy. Sperm-agglutinating antibodies were present in three (2-6%) of 117 fertile men and in 19 (33-9%) of 56 men who had been vasectomized. Twenty-four of the 56 vasectomized men had been studied before vasectomy; sperm-agglutinating antibodies were present in one (4-3%) compared with eight (33-3%) after vasectomy. No sperm-immobilizing antibodies were detected before vasectomy but were present in 10 (17-9%) of the 56 men after vasectomy.


Production and turnover of IgG1 and IgG2 immunoglobulins in the bovine around parturition. Production rates (entry rate into blood plasma) and other metabolic parameters for the IgG1 and IgG2 subclasses of immunoglobulins in mammary secretions (ratio of about 7 to 1) were determined in cows around the time of parturition by both single-injection and continuous-infusion isotope-dilution techniques. Four cows were given a single dose of 150 to 200 muCi of iodine-125 labeled IgG1 and 100 to 250 muCi of iodine-131 labeled IgG2 at 2 to 1 wk before parturition. Four cows, including two of the above, were infused continuously with constant amounts of the labeled immunoglobulins starting at 11 to 4 days before parturition. All cows were maintained until 4 to 6 days after parturition for monitoring the specific activities of iodine-125 labeled IgG1 and iodine-131 labeled IgG2 in the plasma and mammary secretions. Maximum entry rates of IgG1 and IgG2 were between 3 and 1 day prepartum with means of 125 and 60 g/500 kg body weight per day. The exchangeable pool means for IgG1 and IgG2 were 619 and 643 g/500 kg body weight, and both immunoglobulins were divided almost equally between the intra- and extravascular pools. A greatly increased production and a shortened half-life or greater turnover for plasma IgG1 occurs around the time of parturition which can account for the large accumulation of IgG1 in colostrum.


Relationship of temperature and humidity to conception rate of Holstein cows in Hawaii. Weather data and breeding records for a Holstein herd of 1300 cows in Hawaii were evaluated to determine effects of climate on reproductive performance. The dairy is in a coastal climate near latitude 21 degrees N. Average maximum temperature, relative humidity, and resulting temperature-humidity index for the warmest month of the year were 31 C, 44%, and 79. Average minimum temperature and attending values for the same period were 20 C, 96%, and 68. From late April to November, conception rates were correlated negatively with the average temperature-humidity index of each day of the estrous cycle beginning 11 days prior to breeding. Slopes of regression lines differed, suggesting varying sensitivity of conception rate to heat stress on different days of the cycle. The temperature-humidity index of the 2nd day prior to breeding was most closely correlated with conception rate. Conception rates declined from 66% to 35% as the index increased from 68 to 78. Only the temperature-humdity index of the 2nd day prior to breeding had a significant partial correlation coefficient when the index of the 2nd and 1st day prior to breeding, the day of breeding, and the day following breeding were each evaluated with the index of the others held constant.


Influence of glycerol concentration and freezing rate on post-thaw motility of bovine spermatozoa in Continental straws. Semen from each of six bulls was used to study the effects of percent glycerol and rate of freezing on spermatozoa extended in egg yolk-sodium citrate extender and packaged in .25-ml Continental straws. Treatments were arranged factorially and included 5, 6, 7, 8, 9, 10, or 11% (volume/volume) glycerol; freezing rates (time from 5 to -130 C) of 1, 2, 3.5, 7, 12, or 20 min; and post-thaw incubation times of 0 and 2 h at 38 C. Post-thaw motility was similar for spermatozoa frozen in 2 to 20 min, and all means were greater than for spermatozoa frozen in 1 min. Post-thaw motility of spermatozoa frozen in 7% glycerol did not differ from that with 5 to 9% but was superior to that with 10 or 11% glycerol. Although glycerol and freezing rate interacted, 7% glycerol provided survival equal to or greater than that with the other percents of glycerol, regardless of freezing rate.


Suicide and the relational system: a case study in a mental hospital. An investigation in a mental hospital that served as a training center for psychiatric residents revealed that periods of high suicide rates among patients tended to follow upon a decrease in interaction between some authority holders and residents and turnover among top-ranking psychiatrists; and tended to be associated with a low ratio of older to new residents. These instances represent conditions in which residents were likely to lack the support that is needed for a feeling of competence in dealing with patients.


Issues underlying prevalence of "doctor-shopping" behavior. Data were collected on all persons within a sample of upper-and lower-income households who had seen physicians for illness episodes within a year prior to the interview. Forty-eight percent of upper-and 37 percent of lower-income families in the sample had changed doctors because of dissatisfaction with some aspect of the care. Factors related to tendency to shop for doctors in both upper-and lower-income groups were a lack of confidence in doctors' competence, unwillingness of doctors to spend time talking with patients, hostile feelings toward doctors, high cost of services, inconvenience of location and hours, and unfavorable attitudes toward doctors' personal qualities. Hypochondriasis was related to doctorshopping in the upper-income group. Results of this investigation suggest that patients may be becoming more discriminating in their choice of physicians.


Service delivery structure and continuity of care: a case study of a pediatric practice in process of reorganization. The effects of the reorganization of a medical practice on continuity of care were investigated in a case study of a changing pediatric practice. Continuity, which has often been conceptualized as one indicator of quality of care, was measured by an index of which the numerator was the number of visits with own pediatrician and the denominator was the total number of pediatric visits for the year. Increased number of pediatricians and incorporation of the practice into an academic setting resulted in a decline of continuity of care accompanied by a rise in the number of doctor visits for acute illness care. Patient satisfaction, although related in some of its aspects to continuity, was by and large unaffected by the change. The consequences of changes in practice size and goal complexity for interpersonal aspects of patient care and quality of care are discussed.


The effect of psychological distress on physician utilization: a prospective study. This paper examines the hypothesis that psychological distress is causally related to physician utilization among enrollees in a prepaid group practice. Measures of distress are constructed from questions included in a servey interview, while the utilization data come from medical records. Distress levels were measured prior to the period of utilization studied. The results show a positive relationship between distress and physician utilization, which persists even when a variety of sociodemographic, attitudinal, and health status variables have been controlled. The results are discussed in terms of a perspective that emphasizes social-psychological needs as triggers for physician utilization


Psychiatrists and community mental health: normative versus utilitarian incentives. The inability to attract adequate numbers of psychiatrists has been a concern of community mental health (CMH) planners for some time. This paper considers whether normative or utilitarian (i.e., economic) inducements have more of an impact on their participation. Data are drawn from a survey of 946 New York area psychiatrists. These data suggest the likelihood of incremental growth among community psychiatrists because organizational involvement, high quality residency training, and "younger generation" status all are linked to normative commitments to CMH values. Moreover, since political orientation is the strongest single determinant of these values, commitments also can be deliberately stimulated through normative appeals. Yet, our principal finding is that severe utilitarian disincentives tend to undercut the effects of normative inducements and commitments. The paper concludes by examining the social policy implications for community mental health staffing of the primacy of utilitarian considerations among psychiatrists.


Replicating psychiatric ratings through multiple regression analysis: The Midtown Manhattan Restudy. This paper examines three related questions: First, can psychiatrists' judgments be successfully predicted by multiple regression techniques? Second, assuming that they can, are such ratings a valid measure of mental health for the same sample at a later point in time? Third, what is the relation between mental health ratings made in 1954 and such subsequently reported behavioral outcomes as nervous breakdown, mental hospitalization, or seeking professional help for emotional problems? The evidence presented warrants two conclusion. (1) The computer-derived mental health ratings are an adequate substitute for the original ratings. The regression equation accounts for 69 percent of the variance in those ratings; and the computer-derived ratings behave in the same way as the psychiatrists' ratings in relation to other variables. (2) However, neither the psychiatrists' ratings nor the computer-derived ratings are very accurate in predicting subsequent self-reported behavior indicative of mental impairment.


Transformation of cercariae to schistosomula: a quantitative comparison of transformation techniques and of infectivity by different injection routes of the organisms produced. Six transformation techniques ((1) incubation of cercariae in isotonic medium; (ii) penetration of isolated skin; (iii) stimulation with crude egg lecithin; (iv) mechanical disruption by passage through a syringe and 21 gauge needle; (v) by whorling of cercariae with a vortex mixer; (vi) syringe transformation followed by incubation) were evaluated. The organism produced were assessed for infectivity for mice by 6 different routes of infection (percutaneous, intradermal, subcutaneous, intra-peritoneal, intravenous and intra-muscular). At perfusion the largest numbers of adult worms were recovered from mice injected intramuscularly with organisms produced by the syringe technique and control mice given cercariae percutaneously. The peak for migration of schistosomula (following syringe transformation and intramuscular injection) through the lungs and the appearance of adult worms in the mesenteries was shown to be similar to cercarie administered percutaneously.


The pathology of experimental Schistosoma bovis infection in sheep. Five desert sheep were exposed to 5000 or 10000 Schistosoma bovis cercariae each, and the parasitological clinical and pathological parameters were recorded. The pre-patent period was approximately 7 weeks and from that time onwards, the animals became progressively ill and emaciated. Following necropsy at the 12th week, a percentage schistosome recovery ranging from 36%--63.6% was found, and there were high egg densities in the intestinal tract and the liver. These organs revealed severe pathological lesions which were described in detail along with the changes occurring in other tissues.


Studies with Brugia pahangi. 14. Intrauterine development of the microfilaria and a comparison with other filarial species. The intrauterine development of Brugia pahangi embryos was followed from after fertilization to birth, using light and electron microscopy. The origin and development of the sheath of the microfilaria and its possible role in the nutrition of the developing embryo were particularly investigated. Comparisons were drawn with the intrauterine development of other filarial species. The egg shell of the B. pahangi embryo is distinct from the oolemma and forms the sheath of the microfilaria. It is suggested that the electron dense material released by cells of the uterine wall and passing along the channels between the egg shells of adjacent embryos is nutritive. The death of large numbers of developing embryos in the central uterine lumen is probably caused by overcrowding as their size rapidly increases, leading to nutritional deficiency.


Spectrophotometric analysis of haemoglobins of some digenetic trematodes and their hosts. The haemoglobins of six different species of trematodes: Gastrothylax crumenifer, Srivastavaia indica, Gigantocotyle explanatum, Fasciolopsis buski, Gastrodiscoides hominis, Isoparorchis hypselobagri and their three different hosts: Bubalus bubalis, Sus scrofa, and Wallago attu were spectrophotometrically investigated, and were found to contain porphyrin IX as the common prosthetic group. Oxyhaemoglobin, carbonmonoxy-haemoglobin and reduced haemoglobin of all 6 species of trematodes and their 3 hosts under study gave similar absorption maxima. Distinct differences were, however, observed in the nature of the spectral curves of cyanmethaemoglobin which exhibit 2 absorption maxima in the beta and the alpha region in the case of all trematodes whereas in the case of similar host haemoglobin derivatives only one single broad peak in the 536-540 nm region was obtained. With respect to pyridine derivatives all the trematode haemoglobins show a sharp peak in the alpha region and a minor hump in the beta region except Gastrothylax crumenifer. All three host pyridine haemoglobin derivatives show only a single broad peak at 570 nm.


The role of native domestic animals in the dissemination of Echinococcus infection among dogs in the state of Kuwait. Infection with hydatid cysts of domestic animals slaughtered by private individuals and at the Government Central Slaughterhouse is recorded. Both fertile and non-fertile cysts were seen in the infected animals. The home slaughtered sheep seems to play an important role in the dissemination of the parasite and the life cycle of Echinococcus granulosus in the State of Kuwait is assumed to be sheep--dog--sheep.


Studies on trematodes of the genus Lecithodendrium Looss, 1896 from some Egyptian bats, with a description of two new species. The genus Lecithodendrium Looss, 1896 is reviewed and its prevalence in some Egyptian bats is reported. Lecithodendrium aegyptiacus n.sp. is described from Asellia tridens tridens and Rhinopoma hardwickei cystops. It can be easily differentiated from other species of the genus by the lobulation of the ovary and testes and the presence of tegumental spines all over the body of the trematode. Lecithodendrium duboisi n.sp. is described from Taphozous nudiventris nudiventris. It differs from the other known species of the genus by the characteristic arrangement of the vitellaria in the form of a continuous band posterior to the testes, while in the other species of the genus the vitellaria occur in the form of two separate clusters of post-testicular vitelline follicles.


[Onchocerca raillieti n.sp. (Filarioidea) from a domestic donkey in Africa]. Onchocerca raillieti sp. n. (Filarioidea), from the domestic donkey (Equus asinus) in Africa, is described. The species is compared to O. bohmi (Supperer, 1953) n.comb, O. reticulata Diesing, 1841, O. cervicalis Railliet et Henry, 1910, O. flexuosa (Wedl, 1856) and O. armillata Railliet et Henry, 1909 and can be differentiated by numerous characters of which the most important are the anterior region of the female (which is straight and slender, 6 to 8 cm long, and bears longitudinal striae) and the 10 symmetrically arranged pairs of caudal papillae. O. raillieti seems to be a primitive species by several characters (caudal papillae, cervical papillae, oesophagus, vulva and cuticle.)


Comparison of crossbred and purebred selection for a heterotic trait in highly selected populations of Tribolium. Selection on the basis of crossbred performance (RRS) was compared for 11 generations to within-line selection based on purebred performance (WLS) for a heterotic trait, 13-day larval weight in Tribolium populations previously subjected to 30 generations of purebred selection. RRS crossbreds gained slightly less than crossbreds of WLS populations. RRS purebreds showed a much smaller composite populations were greater than those observed for the continued populations. A model for the genetic control of larval weight is suggested in which there are both dominant and overdominant loci and homozygotes are less fit than heterozygotes.


Fuzzy, a hypotrichotic mutant in linkage group I of the Norway rat. A new recessive hypotrichosis gene in the rat designated fuzzy (fz) is described. Fuzzy is linked to albino (c) in linkage group I with a 18.13 +/- 3.05 percent recombination. After an initial sparse hair coat, the fuzzy animals rapidly become devoid of hair. Histologically the skin of these animals has poorly developed, and often cystic hair follicles that contain accumulations of keratinacious material.


Immunological diagnosis of IgD paraprotein. IgD monoclonal peaks are relatively small, with broad bases, and are preferentially of gamma-1 or beta mobility. Often IgDgamma paraproteins can only be detected after proper dilution or reduction of the patient's serum. Assay for Bence Jones protein should not be neglected, and if it is present, the co-existence of IgD monoclonal gammopathy should be suspected.


Immunology of DNA. V. Analysis of DNA/anti-DNA complexes. DNA/anti-DNA complexes were studied by equilibrium density centrifugation in CsC1 and by zonal centrifugation in sucrose gradients. Complexes prepared of circular DNA preparations PM2 DNA or SV40 DNA with anti-DNA obtained from patients with systemic lupus erythematosus were found to be stable under the conditions of CsC1 equilibrium centrifugation. This enabled homogeneous complexes of DNA and anti-DNA of composition AgAb1, AgAb2, AgAb3 etc to be isolated. The stability of these complexes, their banding pattern in CsC1 gradients and their sedimentation behaviour suggest that anti-DNA binds to DNA in a monogamous bivalent way.


Selection for hematocrit percent in the house mouse. Two selection experiments were designed to change hematocrit percent. In the first experiment the mice were measured at 60 days and elevated hematocritis were achieved in the first generation with no further response. In the second experiment hematocritis were taken at 100 days and two-way response continued for three generations after which the difference between the high and low lines remained constant. Realized heritability was 71-97 percent in the first generation in one experiment and 24-30 percent for three generations in the second. These compare to an estimate of the degree of genetic determination based on 21 inbred strains of 40 percent. The evidence based on the selection experiments and crosses between inbred strains indicates that few genes are involved in the genetic control of normal hematocrit levels found within inbred strains of mice. The realtionship between hematocrit level and systolic blood pressure suggested by other studies was not a consistent finding in our studies.


Electrophoretic and cytogenetic studies of Chironomus utahensis. Cellulose acetate electrophoresis of Chironomus utahensis hemolymph demonstrated a six-band pattern for hemoglobins. Three major and three minor bands made up the electropherogram. Slight variations from this general pattern were found in less than 10 percent of the population and may represent ontogenetic changes, genetic variation or slight changes in the electrophoretic conditions. No variations could be correlated with the age of the culture, sex, or site of collection. Cytogenetic observations of the salivary glands revealed three large and one small pair of independent polytene chromosomes. Comparisons of electrophoretic patterns of hemoglobins and chromosome banding patterns with other chironomid species will help to clarify their taxonomic and evolutionary relationships.


Antisera to prostaglandins - production and characterization. Antisera to prostaglandins of the A,B, E and F groups were elicited by immunization with prostaglandin-protein conjugates. Antibodies to protaglandins of the A and B groups cross-react with each other, but discriminate these two groups of prostaglandins from those of the E and F groups. Antibodies to protaglandins of the E groups, elicited with prostaglandin E-bovine serum albumin (PGE-BSA) conjugates in rabbits, cross-react with prostaglandins of the A and B groups. This cross-reaction is diminished by immunization of rats or mice with PGE-BSA, or by immunization of rabbits with PGE conjugated to gamma globulin or thyroglobulin. Antibodies to PGF have a marked group specificity and discriminate between this group of prostaglandins and prostaglandins of the A, B and E groups. All the antibodies produced do not discriminate between individual prostaglandins within the group.


Immunoelectrophoretic quantitation of trace proteins. A method is suggested for increasing the sensitivity of quantitative immunoelectrophoresis to a level comparable with radioimmunoassay. This is achieved by electrophoretic elution of antigen from 0.1-10 ml samples placed in glass reservoirs on the electrophoresis plate.


Primary cultures of human spleen macrophages in vitro. A method for establishing and maintaining primary cultures of human spleen macrophages is described. The cultured cells have been characterized as macrophages by virtue of their adherence, morphology, phagocyte activity, surface Fc receptor, and the production of lysozyme.


Male determining factor on chromosome 3 in the mosquito, Culex tritaeniorhynchus. Recent experiments indicate that the sex allele M in different populations of Culex tritaeniorhynchus may be present in different linkage groups. In some laboratory wild-type and mutant stocks, M was found to be unlinked to the mutants of linkage group I. Further experiments have demonstrated that in these stocks M is linked to the mutants in linkage group III. Thus, M may be associated with either linkage group I or III. All other markers within a linkage group appear to remain linked to each other and the recombination frequencies among linked markers remain unaltered irrespective of whether or not the M allele was present. The females behave as the homogametic sex in crosses with both types of males. The M allele when associated with linkage group I has been designated M1, when associated with linkage group III it is designated M3. The gene order when M3 is present in linkage group III is Lp-M3-Adh-bw-ae.


Dieldrin-induced chromosome damage in mouse bone-marrow and WI-38 human lung cells. Several concentrations of the insecticide dieldrin were tested on in vivo bone marrow cells of STS mice and in vitro human embryonic lung cells of the WI-38 cell line. The insecticide caused pronounced mitotic inhibition and produced a 2 to 3-fold increase in chromosome abnormalities such as breaks and fragments in concentrations as low as 1 mg/kg in STS mice bone marrow cells, and 1 mug/ml in human WI-38 cells. The chemical also produced chromosome interchanges and rings. A few cells from the control groups exhibited breaks and fragments but not exchange figures and rings. Cytotoxic studies using the WI-38 cell line revealed dose-response and time-response reactions to dieldrin. Cell toxicity was most pronounced at the 50 mug/ml treatment level, producing 100 percent cell degeneration within 6 hours.


Desired family size and sex of children. During 1975, data were obtained from 1016 unmarried Caucasian students on their preference for family size, combination of sexes within the desired size, and permutation of sexes within the desired combination. The most desired family size by both female and male respondents was two children, but the average size was more than 2.46 children. Combinations involving both sexes of children were preferred over single sexes in all families of two or more children. The preference for the first-born to be male was consistent in all combinations of male and female children. Considering all desired family sizes and combinations of sexes of children the resulting sex ratio was 137.9 males:100 females.


The use of the IgG fraction of typing sera in the lymphocytotoxic test: a comparison with other cytotoxic methods. The application of a simple batch method for the isolation of IgG from weakly lymphocytotoxic sera is described. The use of purified IgG as an antibody source at the serum concentration or up to tentimes that level resulted in the conversion of 25 out of 28 previously weak or non-reactive cytotoxic sera into potentially useful tissue typing reagents. The sensitivity of this technique was assessed by comparison with five cytotoxic test systems.


PGM3 locus and its genetic polymorphism in leucocytes of goats. PGM3 activity was investigated in 150 'Boerbok' goats and 132 Angora goats by means of horizontal starch gel electrophoresis. In 'Boerbok' goats no polymorphism was found. In Angora goats three different phenotypes have been recognized: F, S, and FS. The results suggest the occurrence of two common alleles: PGM3-F and PGM3-S at an autosomal locus with frequencies of 0.6176 and 0.3824, respectively.


An allele affecting display coloration in the fish, Poeciliopsis viriosa. The inheritance of an autosomal recessive gene affecting the distribution of yellow xanthrophores on the body scales and fins of P. viriosa is described. Individual males and females having the mutant phenotype, gray, lack the normal olivaceous body coloration. Also, mutant males cannot exhibit the brassy display coloration used by wild-type males in mating and aggressive encounters.


Characteristics of natural anti-NP antibodies in different strains of mice. Characteristics (titre and fine-specificity) of natural anti-NP antibodies were determined in eighteen inbred strains of mice. We found systematic titre and fine-specificity differences between different strains. At least five types of strains could be easily detected but the data indicate that the actual number is greater. Strains sharing an Ig allotype tended to have less different anti-NP antibodies than those not sharing the allotype. Fine-specificity of natural anti-NP antibodies resembled fine-specificity characteristics in immune anti-NP antibodies of the same strains. Both are probably controlled by V genes. The data indicate that fine-specificity of antibodies has a great resolving power in the study of Mendelian V genes.


Absence of an effect of t-alleles on epididymal and testicular metabolism of 5-3H-uridine in mice. Earlier reports have suggested that the epididymis secretes RNA, and that the amount of these secretions varies among T/t6, T/t12 and C57BR mice. In this report, the epididymal perfusate, the total uptake and incorporation of 5-3H-uridine into the epididymis and testicle were examined. Mice examined were T/t6 and +/+ (B6D2F1) and their F1 hybrids, and T/t12 and +/+ (Swiss Webster) and their F1 hybrids. No t-related or age-related effect was seen. However, the F1 hybrids of T/t6 and +/+ (B6D2F1) were significantly lower than the parents at the 4-hour interval.


Haemagglutinins produced in vitro by human lymphoblastoid cells. Haemagglutinins in the supernatants of four human lymphoblastoid lines have been partially purified by ammonium sulphate precipitation, centrifugation on a sucrose gradient or passage through a Sephadex G-200 column. Haemagglutinating activity in all cases appears to be associated with a high molecular weight fraction with the characteristics of IgM and activity can be recovered by elution of material adsorbed onto an anti-IgM column. On iso-electric focusing, a very small number of molecular species seems to be involved. It is likely that these lines constitute the first in vitro human systems in which the synthesis of homogenous immunoglobulins with known antibody specificity can be studied.


Studies on the membrane glycoprotein defect of En(a-) erythrocytes. I. Biochemical aspects. Discontinuous sodium dodecylsulphate-polyacrylamide gel electrophoresis, followed by periodic acid/Schiff or Coomassie staining and densitometry, spectrophotometric and gas-liquid chromatographic carbohydrate analyses as well as heterophile agglutinins are employed to study the nature of the membrane glycoprotein defect in En(a-) erythrocytes from Finland and England, heterozygous Ena red cells from Finland and the erythrocytes of two individuals from Switzerland. The results suggest that En(a-) cells lack the major membrane sialoglycoprotein, the so-called MN glycoprotein. Heterozygous Ena erythrocytes from Finland and those from Switzerland have only about half of the normal amount of MN glycoprotein. The molecular weight of the major Coomassie staining membrane protein (component III) is increased by approx. 5000 and 3000 daltons in En(a-) and the other red cells respectively. Some aspects of this membrane defect are discussed.


Significance of specific ovarian receptors for syngeneic naturally-occurring haemagglutinating anti-A antibodies. Haemagglutinins which specifically combine with membrane determinants of human blood group A erythrocytes and which are distinguishable from any other haemagglutinin specificities display marked sex dependency in C57BL/10 mice. All the sera of 80-day-old C57BL/10 females exert moderate to strong anti-A haemagglutinin activities which could be detected only in approximately half of the sera of the males of the same age. Investigations of the murine tissues revealed that the production of anti-A haemagglutinins in females is reflected by simultaneous synthesis of strong endogenous receptors detected in the ovaries and associated with water-soluble glycolipid fractions. The receptor activity was demonstrated by means of haemagglutination inhibition in comparison with appropriate controls and glycolipid preparations from seventeen other different male and female tissues, and the inhibitory effects exerted by the ovarian glycolipids were statistically significant on the basis of multiple comparisons at the 1% level in each possible pair of effects.


Studies on the membrane glycoprotein defect of En(a-) erythrocytes. II. MN antigenic properties of En(a-) erythrocytes. En(a-) and EnaEn red cells from different sources were studied using biochemical and serological methods. The results suggest that Finnish En(a-) erythrocytes contain only "N" but no M antigenic properties. Data on the members of the English En(a-) family suggest that English En(a-) red cells exhibit a combination of three rare alterations. The English En(a-) individuals are apparently heterozygous for the defects En and Ms, to all appearances, converted to a M ("M") antigen. These extraordinary data are brought to light by investigations on the children of the propositus (G.P. and J.P.), whose red cells are M-N+S-s+"N"+"M"- and M-N+S+s+"N"+"M"+ respectively. Sodium dodecylsulphate polyacrylamide gel electrophoretic results indicate that the MN glycoprotein content is decreased by about 50% in all English S+s+EnaEn red cells, the Ss glycoprotein being normal. G.P. erythrocytes, however, have only about half of the normal MN and Ss glycoprotein content.


Codominant inheritance in immunogenetic (IR-gene) systems. Immunogenetic (IR-gene) systems consist of animals showing different quantitative antibody responses when immunized with similar doses of a given antigen. Strains of animals giving high and low antibody titres are described as high and low responders, respectively. The degree of dominance in F1 hybrid strains, obtained from a cross between high and low responder parents, can readily be calculated using the dominance index formula, which takes the value of +1 for complete dominance, -1 for complete recessivity and the value of zero for no dominance. In reviewing 1527 F1 animals, obtained from ninety-one immunogenetic systems, the degree of diminance (d) was found to be: +0-0076 +/- 0-1053 (mean +/- s.e.), which is close to a value of zero and this is consistent with codominant inheritance. It is suggested that in immunogenetic systems, both alleles are expressed as codominant genes.


The use of early embryo aggregation derived mouse chimaeras. III. A tool of immunogenetics. Early embryo aggregation derived chimaeras have proven a valuable tool to biologists concerned with various aspects of mammalian development. The use of this model is discussed here in respect of its application to the field of immunogenetics and also to possible future exploitation. Chimaeras have already provided information concerning various areas of immunogenetics ranging from tolerance, control of antibody response, allotype expression, gene transfer and its possible influence upon the immune response. These are reviewed here.


Effects of adrenalectomy and hypophysectomy on water and electrolyte metabolism in male and female rats with inherited hypothalamic diabetes insipidus (Brattleboro strain). Observations on water and electrolyte metabolism after hypophysectomy or adrenalectomy, in male and female rats with hereditary hypothalamic diabetes insipidus (Brattleboro strain) are confirmed and extended. The diabetic (homozygous, DI) state relative to the non-diabetic (heterozygous, non-DI) state was characterized by (1) water intake of 55-120% body weight; (2) copious urine hypo-osmotic to plasma; (3) greater excretory rates of total solute, Na, Ca and Mg; (4) similar plasma composition except that in male DI rats, K concentration was less, and in female DI rats osmolarity was higher; (5) glomerular filtration rates (GFR) were similar with close correlations between: food and water intakes, water intake and output, urinary Na and K, Na and Cl, K and Cl, and Ca and Mg; (6) both female DI and non-DI rats had lower urinary Na:K ratios and lower plasma Na concentrations than males; (7) female DI rats excreted relatively larger amounts of K and Cl, and had higher plasma Ca concentrations than other groups. Hypophysectomized DI rats had decreased water intake and urine output, decreased solute excretion, decreased loss of osmotically free water, lower excretory rates of Na, K and Cl, and increased urinary osmolarity and K concentrations. Hypophysectomized non-DI rats had increased urinary excretory rates, decreased solute excretion (by 60-70%), decreased osmotically free water absorption, decreased urinary osmolarity, Na and K concentrations, and increased excretory rates of Ca and Mg. Hypophysectomized DI and non-DI rats had increased plasma osmolarity and Na concentration. Plasma renin activities (PRA) were higher in DI than in non-DI rats with female values lower than those of males; values for both sexes of DI and non-DI rats were reduced after hypophysectomy. Adrenalectomized DI rats had about a 50% reduction in water intake, urine output and free water clearance, increased urinary concentration of electrolytes and total solute by day 4 after operation; their Na balance (dietary:urine) did not change significantly in contrast to adrenalectomized non-DI rats in which a greater percentage of dietary Na appeared in the urine. GFR was similarly reduced in adrenalectomized DI and non-DI rats. Plasma osmolarity increased in adrenalectomized male DI, decreased in female DI and non-DI, and did not change in male non-DI rats. Plasma K concentrations increased after adrenalectomy in all groups, only non-DI rats had a significantly decreased plasma Na concentration. There was no sex difference in pituitary oxytocic activity but it was consistently reduced in DI rats; there was little change after adrenalectomy in male DI and non-DI rats; but there was an increase in DI and non-DI females. Pituitaries of DI rats had no measurable ADH activity (except the inherent activity of oxytocin). Pituitary ADH values for male and female non-DI rats were similar and were unaffected by adrenalectomy.


Parathyroid hormone and eggshell calcification in Japanese quail. The effect of parathyroid hormone (PTH) on egg-shell calcification has been investigated in egg-laying Japanese quail. Lilly parathyroid extract (PTE) when injected into quail within 2-6 h of oviposition caused a significantly increased deposition of a chronic 45Ca label into the sequential egg-shell compared with the previous egg in the clutch, indicating increased mobilization of bone Ca and its subsequent incorporation into the egg-shell. At the same time egg-shell weight/unit area and egg-shell Ca/unit area were significantly decreased. Parathyroid extract injected 12-16 after oviposition had none of these effects. Purified PTH also caused a significant decrease in egg-shell weight/unit area if injected within 2-6 h of oviposition. This result indicated an action of PTH either directly or indirectly on the avian oviduct limiting egg-shell calcification. The loss of responses in the 12-16 h treated birds may reflect high endogenous PTH levels with subsequent saturation of target organ receptors.


The response of the brachial ventral horn or Xenopus laevis to forelimb amputation during development. The normal development of the brachial ventral horn of the frog Xenopus laevis and the response of the brachial ventral horn to complete forelimb extirpation at five developmental stages were assessed histologically. Differentiation of brachial ventral horn neurons occurred in pre-metamorphic tadpoles between stages 52/53 and 57. Mean cell number in the brachial ventral horn reached a peak of 2576 (S.E.M. equals +/- 269, N equals 2) per side of the spinal cord at stage 55 and decreased to 1070 (S.E.M. equals +/- 35, n equals 7) by the end of metamorphosis. Cell degeneration was presumed to be the mode of cell loss since it was most prevalent during the period of rapid decrease in cell numbers. The response of the ventral horn to forelimb removal varied with the stage of the animal at amputation. Following amputation at stage 52/53 or 54 the ipsilateral ventral horn neurons appeared less differentiated than those on the control side and a rapid cell loss of about 80% occurred on the operated side. These effects occurred more rapidly after ablation at stage 54 than at stage 52/53. Amputation at stage 58, 61, or 66 caused chromatolysis in the ventral horn, a period of relative cell excess on the operated side, and a delayed neuronal loss of 32-66%. It was concluded that excess cell degeneration accounted for cell loss and that suppression of normal neuronal degeneration caused the relative cell excess on the operated side. The data indicate that the brachial ventral horn was indifferent to the periphery before stage 54, was quickly affected by limb removal between stages 54 and 58, and by stage 58 had entered a phase in which a delay preceded cell death. No forelimb regeneration occurred.


Scanning electron microscopy of lithium-induced exogastrulae of Xenopus laevis. Lithium-induced exogastrulae are abnormal embryos which fail to complete gastrulation and do not form normal neural structures. Scanning electron microscopy has been used to compare the surface structure of the ectoderm cells of exogastrulae with that of the ectoderm cells of normal embryos and has shown that the appearance of ciliated cells is delayed in exogastrulae. In addition, the structure of endoderm cells, which remain exposed in these embryos, has been studied.


Injected nuclei in frog oocytes: fate, enlargement, and chromatin dispersal. A method is described by which nuclei associated with some cytoplasm can be rapidly prepared from a suspension of cells. The method involves the use of lysolecithin and bovine serum albumin. Oocytes of Xenopus laevis were injected with about 200 nuclei perpared from human HeLa cells by this method. Nuclei were deposited in oocyte cytoplasm, in the oocyte nucleus, or in the dispersed contents of a ruptured oocyte nucleus. Injected HeLa nuclei enlarge up to several hundred times in volume in the course of a few days. Their enlargement is associated with chromatin dispersion, increased binding of an acidic dye, and with the reduction in size, and eventual disappearance, of nucleoli. The amount of HeLa nucleus enlargement is much greater when the oocyte nucleus is ruptured. The fate of injected nuclei was followed by the use of HeLa nuclei whose DNA had been previously labelled with [3H]thymidine. Labelled DNA does not pass from injected HeLa nuclei into the oocyte nucleus. Injected nuclei appear not to fuse with each other or with the oocyte nucleus. Nuclei prepared by the above method look morphologically healthy in oocytes cultured in vitro for up to one month after nuclear injection. Nuclei prepared by other methods, such as those involving the use of detergents, undergo deterioration within a few days after injection into oocytes.


Injected nuclei in frog oocytes:RNA synthesis and protein exchange. Nuclei from HeLa and other mammalian cells have been injected into Xenopus oocytes. The synthesis, uptake, and release of RNA and proteins by injected nuclei have been investigated by autoradiography. Injected nuclei which undergo enlargement synthesize RNA continuously for up to 28 days. When oocytes are incubated in [3H]uridine or [3H]guanosine, injected nuclei are labelled nearly as strongly as the nucleoli, but much more strongly than the nucleoplasm of the oocyte's germinal vesicle. Injected nuclei appear to increase their rate of RNA synthesis during incubation in oocytes. This apparent increase in the rate of RNA synthesis is correlated with nuclear enlargement, as well as with the loss of protein from injected nuclei and with their uptake of histone and nonhistone proteins from oocyte cytoplasm. Injected HeLa nuclei lose most of the previously synthesized RNA from their nucleoplasm, but little if any of the RNA from their remaining nucleoli.


Blastemal kinetics and pattern formation during amphibian limb regeneration. To investigate whether the uniqueness of proximal and distal limb regenerates could be attributed simply to differing blastemal growth characteristics, their increase in volume, cell number and cell-cycle times were determined. With respect to these parameters proximal and distal blastemas were identical and, furthermore, no evidence could be found for the existance of separate growth zones such as an apical proliferation centre or a progress zone within the blastema. It was therefore concluded that level-specific properties of the blastemal cells play the major role in determining the structure of the regenerate, not their growth characteristics. The only discernible difference was in the cell number within the two types of blastema at the onset of cartilage redifferentiation - proximal regenerates had 60% more cells. Thus it seems that the larger the pattern to be regenerated (the more proximal the amputation plane), the larger the primordium within which that pattern first appears. These two conclusions are discussed in relation to current theories of pattern formation during limb regeneration and development and a few way of envisaging the regeneration of pattern is described.


Three-dimensional anatomy of the 8-day mouse concepts: a study by scanning electron microscopy. The three-dimensional anatomy of the 8-day mouse concepts was studied by scanning electron microscopy aided by microdissection within the microscope specimen chamber. Attention was given to the relationship of the extra-embryonic membranes and their subtended compartments and particular emphasis was placed on the 'inverted' condition of the embryo at this stage of development. The main points brought forth in this study are: (1) the five basic brain segments are discernible on the basis of surface contour; (2) the cervical fold, extending from the ventrum of the metencephalon to the somatopleure, forms a partition which separates the branchial region from the rest of the amniotic space; (3) the procephalic membrane bifurcates in a vertical plane to form the splanchnopeure and somatopleure lateral to the forebrain, and it bifurcates horizontally to form the dorsal and ventral coverings of the pericardial coelom; (4) the anttrum of the pericardial-peritoneal canal opens into the lateral coelom posterior to the cervical fold; (5) the midgut of the embryo is delineated laterally by longitudinal grooves connecting the foregut and hindgut antra; (6) embryonic ectoderm in the neural-fold region is formed by a single layer of pseudostratified columnar cells; (7) the allantois is hollow near its base and the inner surface is formed by a discontinuous layer of squamous cells; (8) blood islands in the extra-embryonic mesoderm form a ring of bulges around the middle of the exocoel. Other structures such as the ectoplacental cavity, the ectoplacental cone and the parietal capsule are also described.


Morphological changes associated with the growth cycle of vibrissal follicles in the rat. Morphological changes which occur in the growth cycle of the rat vibrissal follicle during the transitional period between consecutive anagen phases are described. In contrast with pelage hair follicles, there is no shortening of the follicle, no formation of a papilla 'rest' and no close synchrony between club differentiation and follicle regression. Telogen is therefore considered to occur after loss of the matrix of the hair bulb and maximal diminution of the dermal papilla to a small aggregation of cells. These difference are discussed in relation to current nomenclature of the hair cycle and the function of the vibrissal follicle.


Ultrastructural observations of preimplantation stages of the sheep. Sheep embryos were examined with the electron microscope in order to characterize their organelles and the changes that occur during the preimplantation period. The first sign of differentiation of trophoblast cells was the appearance of junctions between external cells at the 16-cell stage. Nucleoli developed a granular component suggesting the synthesis of ribosomal RNA at the 16-cell stage also. Centrioles were seen as early as the 8-cell stage. Intracytoplasmic vesicles were present in large numbers in all cleavage stages but disappeared at blastulation. Mitochondria progressed from a very electron-dense hook- or U-shaped form with a few cristae to a cylindrical or spherical form of light density with many transverse cristae. Microvilli were not seen until the blastocyst stage and then only on the exterior surface of the trophoblast cells. Crystalloid or virus inclusions were not observed. It was concluded that the fine structure and developmental changes in the early sheep embryo are very similar to those of other mammalian species.


Direct exposure of mouse embryonic limb-buds to 5-bromodeoxyuridine in vitro and its effect on chondrogenesis: increasing resistance to the analog at successive stages of development. The inhibitory effect of 5-bromodeoxyuridine (BudR) - an analog of thymidine - on embryonic mouse limb-buds was studied in vitro employing an organ-culture system. The effect was found to be dose-related and also depended on the developmental stage of the donor embryos. Limbs at an early stage development (early 11 th-day embryos, somite stage 26-29) were extremely sensitive to the analog. Treatment with low levels (2-4 mug/ml) and for a relatively short period of time in cluture (2-3 days) completely and irreversibly suppressed chondrogenesis in these explants. Limbs from older embryos (somite stage 40 and up) were found to be much less sensitive to the inhibitory effect of the  drug; a prolonged exposure to a much higher dose (100-150 mug/ml) resulted in an incomplete suppression of chondrogesesis. Only a 20% inhibition was observed in the cultures of limbs from mid-13th-day mouse embryos. After continuous growth in vitro, the limbs became progressively resistent to the analog and towards the end of the culture period had become refractory to the drug. The time of complete insensitivity appeared earlier in the cures of the limbs taken from older embryos than in the explants of youngerlimbs. These studies show that as limbs continue to differentiate in vivo or in vitro, they become increasingly resistent to the inhibitory effect of BudR in at least as far as the effect on the process of chondrogenesis is concerned. It is suggested that the relative sensitivity or insensitivity to the inhibitory effect of BudR may prove to be a useful parameter in evaluating the developmental stage of an organ.


Patterns of lactic dehydrogenase isozymes in mouse embryos over the implantation period in vivo and in vitro. Following blastocyst implantation, or outgrowth in vitro, the LDH isozyme pattern changes from that of the maternally inherited B subunit isozyme form (LDH-1) to a pattern dominated by A subunits (Auerbach & Brinster, 1967, 1968). In preimplantation embryos we have observed additional isozyme bands, as yet unidentified. An analysis of the pattern of newly synthesized LDH isozymes and specific activity of LDH in different regions of early postimplantation embryos suggests that there is a sequantial activation of A and B subunits, and that activity first appears in ICM- (inner cell mass) derived tissues and then in trophoblast-derived tissues. In vitro, in the absence of ICM cells, the transition of LDH-isozyme pattern does not occur in outgrowing trophoblast giant cells. This suggests a possible inductive interaction between ICM and trophoblast.


[The histogenesis of somites in the chick]. The somites of the thoracic region of chick embryos incubated for 2 (stages 13-15) and 3 days (stages 17-19) have been examined cytologically and ultrastructurally. Cell contacts and cell arrangement were studied first in spherical somites. The further development of the spherical somite is characterized by changes in the cell arrangement. According to these changes two somitic cell populations can be distinquished: a ventral one, which during the third day loses its epithelial arrangement and becomes disaggregated, and a dorsal one, the dermatome, which remains spithlial for a longer time. Some cells of the ventral group reaggregate on the apical surface of the dermatome cells, and constitute the myotome. The contacts between dermatome and myotome cells as well as between the myotome cells themselves are described. Although the myotome cells appear to be arranged in an epithelial-like order and develop a basement membrane at the sclerotome side, the characteristic contacts and cell polarity of epithelia were not observed. These observations are discussed in relation to the process of cell adhesion and cell communication during the morphogenesis of the secondary mesenchyme.


Evidence that blood pressure controls heart rate in the chick embryo prior to neural control. Blood pressure increases will increase heart rate in intact chick embryos, prior to the development of neural control. Similarly, in surgically isolated hearts, increases in intraventricular fluid pressure will increase the rate of beat. However, fluid pressure applied equally to both interior and exterior surfaces of the isolated heart does not result in increased heart rate. Therefore, we conclude that the increased pressure stretches the heart muscle and that this stretch stimulates the increased heart rate. While heart rate is clearly influenced by blood pressure, the reverse is not true. Propranolol reduces the heart rate to about half normal in intact embryos but does not significantly alter the blood pressure.


Ultrastructural analysis of some functional aspects of Xenopus laevis pancreas during development and metamorphosis. Morphological studies using both light and electron microscope were carried out with the aim of characterizing cells present in the larval and adult pancreas of Xenopus laevis. The following cell types have been seen: (1) exocrine cells, with a very well developed r.e.r. (rough endoplasmic reticulum), well defined Golgi complexes and numerous large secretory granules (A cells); (2) cells without either r.e.r. or secretory granules but with a large number of well developed mitochondria (B cells); (3) endocrine cells often clustered in the typical islets and with small membrane-coated granules showing a very dense central core surrounded by a light halo (C cells). During development, the aspect is seen to change from an unorganized tissue in which the acinar structures are still not clearly visible (stage 42), to a more organized form in which the exocrine cells (A cells) are seen to be arranged around the lumen of the acinus together with some B cells. At the stages 54-56, an increasing number of acini surrounded both by A and B cells was observed. At about stage 61, large quantities of necrotic cells were seen and it became more difficult to individualize the acinar organization found in the preceding stages. Finally, there are no necrotic cells in the adult but only A, B cells which are organized in well developed acinar structures and C cells. The investigation also included a study of some pancreatic enzymes (lipase and amylase) synthesized during larval life. Lipase activity shows a peak at stage 54-56 in which the most well organized tissue of the entire larval life was observed. The activity then decreases, reaching a minimum at stage 66, after which it rapidly rises. Maximum amylase activity occurs at stage 51 after which there is a decrease, to a minimum at stage 66. The activity then remains at constant level.


The composition of gallstones from geriatric patients. Methods for the determination of cholesterol and of black substances in gallstones. 78 female and 31 male Danish gallstone cases found by autopsy were studied. The mass of the gallstone(s) from each patient was recorded and the stones were ground. The content of cholesterol in the mixed material from each patient was determined, using the Liebermann-Burchard reaction. The ratio Gallstone(s) ash-mass/Gallstone(s)-mass was determined, and where this ratio exceeded 0.10, calcium and phosphate determinations were carried out. Subjective description of the stones as 'mixed stones' or 'pigment stones' was substituted by visual comparison of the ground gallstones with a 'grey scale' (black was given the highest value). The values of this quantity and the ash values generally increased with a decreasing content of cholesterol. The content of cholesterol in the gallstones increased with increasing stone mass. The chemical composition of gallstones found by surgery seems to differ from that of gallstones found by autopsy.


[Simultaneous radioimmunassay for urinary thyroxine (T4) and triioldothyronine (T3) (AUTHOR'S TRANSL)]. A radioimmunoassay for the determination of thyroxine (T4) and triiodothyronine (T3) in urine was developed. The extraction of a sample, the incubations with T3-und subsequently T4-antibody and the elutions of the respective bound fractions are performed all on the same Sephadex column. This principle can be applied to as many as 120 simultaneous determinations. The interassay coefficients of variation were 20.1% for T3 and 10.6% for T4, respectively. The recovery of standards added to urine was 107 +/- 8% (mean +/- SD) for T3 and 102 +/- 8% for T4. The 24 h collections of urine from healthy controls contained 1.70 +/- 0.40 mug T3 and 1.44 +/- 0.51 mug T4 (mean +/- SD, N=20). Three hourly fractions of the urinary excretion collected from 6 a.m. through 9 p.m. showed a significant (p less than 0.0005) elevation of the T4 excretion as compared to the night fraction, whereas an increased T3 excretion was only observed from 6-9 P.M. The T4 excretion was reduced in primary hypothyroidism (0.48 +/- 0.47 mug per 24 h, p less than 0.0005), whereas the T3 excretion was not that markedly reduced (1.30 +/-0.80 mug/d), pointing to the known residual T3 secretion. A reduced T4 excretion (0.85 +/- 0.34 mug/d, p less than 0.00005) contrasted with the normal T3 excretion in patients with endemic goiter, indicating the known preferential T3 secretion in iodine deficiency states. T3 thyrotoxicosis was accompanied by an elevated T3 excretion with normal urinary T4. Normal excretion of T4 and T3 were observed in patients with persistantly suppressed serum TSH levels after successful treatment for hyperthyroidism.


Are there long-term "literal copies" of visually presented words? Evidence for the hypothesis that the appearance of visually presented words is stored in "literal copy" form is critically evaluated and shown to be inconclusive. An experiment in which students were required to retain information about zero, one, or two visual properties of words is reported. A strong version of the literal-copy hypothesis predicts that retention of both case and color should be equally good under instructions to remember one of these attributes and instructions to remember both. However, the results were inconsistent with predictions from this hypothesis. A model that assumes that each visual attribute is stored independently in abstract propositional form provided a good quantitative fit to the data.


Memory scanning of organized visual material. A recognition memory experiment investigated memory scanning when stimuli were organized but not easily labeled verbally. Subjects were shown a series of three, four, or five pictures followed by a probe stimulus in a paradigm similar to that introduced by Sternberg. Reaction time to the test stimulus served as the dependent measure. The principle findings indicated that the organization of the to-be-remembered sets had a pronounced influence on performance. When sets were disorganized, the retrieval appeared to be a serial process, since reaction time increased with set size. With organized sets, reaction time was independent of set size, suggesting a parallel search.


Repetition and acoustic contrast in short-term memory for letter sequences. Memory for sequences of briefly presented letters was examined to discover the effects of intraserial repetition and acoustic contrast on recall of a critical letter pair. The critical pairs were either repeated or nonrepeated letters presented in an acoustically contrasting or noncontrasting sequence. The hypothesis was tested that recall of repeated letters and contrasting nonrepeated letter pairs would depend on the lag between their presentations. Immediate recall of both letters (but not recall of at least one letter) of a critical pair was enhanced when the pair was a repetition or acoustically contrasting but only when the letters of the pair were adjacent. Recall of pairs separated by a lag of two intervening letters was not affected by repetition or contrast. When recall was delayed by a retention interval of eight random digits, the contrast effects disappeared and only the repetition effect remained. The findings are discussed in terms of the coding of attribute tags as cues for retrieval from short-term memory.


Interference in short-term memory from vocalization: aural versus visual modality differences. The Peterson and Peterson short-term memory paradigm involves an interpolated task with several potential dimensions from which interference may orginate: Similarity of items and vocalization. Here we assess the relative interference potency of each on material presented either aurally or visually. Interpolated activity consisting of numbers or words was performed either vocally or silently after either aural or visual presentation of nouns, for which recall was tested after 0, 10, and 30 sec. The magnitude of the vocalization interference effect accounted for 59% and 53% of the total variance at 30 and 10 sec, respectively, whereas the variance associated with similarity was negligible. The effect of similarity emerged dramatically only in the visual presentation condition wherein the silent word task created greater interference than the silent number task. Vocal and silent activity produced differential interference, in partial accord with the dual memory hypothesis.


Lack of memory for nonattended items in dichotic listening. Three experiments were conducted to investigate whether semantic information presented to the unattended ear in a dichotic listening experiment has a memory effect after 30 sec. In all three experiments the Brown-Peterson paradigm was employed. Experiment 1 used the release from proactive inhibition technique and found no evidence that semantic material presented to the unattended ear produced proactive inhibitory effects on attended ear material. Experiment 2 suggests that this result was not due to a memory deficiency resulting from a lack of intent to learn. Experiment 3 indicates that repetition of the same information for three trials to the unattended ear did not enhance memory performance when the material was later presented to the attended ear. Assuming that some semantic processing does occur at the time of input, an interpretation based upon the levels-of-processing approach was suggested as a possibility for explaining the negative results.


Cerebral laterality and verbal processes. Research suggests that we process information by way of two distinct and functionallly separate coding systems. The localization of these two processing systems appears to be somewhat dependent on cerebral laterality, which has been shown to vary in right-handed and left-handed persons. To test the dual coding model, right-handed and left-handed subjects learned lists of abstract and concrete words under various conditions of visual and tactile interference. Right-handed subjects showed a significant superiority in the remembering of highly concrete items, while total recall did not differ reliably between groups.


Perceptual consequences of potentiation in the extraocular muscles: an alternative explanation for adaptation to wedge prisms. Two initial experiments demonstrated that direction aftereffects of potentiation in the extraocular muscles (induced through sustained versional rotation to the side) generally increase as a function of the magnitude and duration of the inducing ocular rotation and can be built up under conditions of varied as well as constant fixation. The results suggest an alternative to perceptual learning accounts of adaptation to wedge prisms, namely, that adaptive changes in perceived distance and direction are induced through a systematic bias in eye posture rather than exposure to informational discrepancy. The muscle potentiation hypothesis was tested directly against a learning hypothesis in a final adaptation experiment. Differences in the decay functions for observers engaged in five different types of interpolated activity strongly support the muscle potentiation explanation.


Visual masking during pursuit eye movements. In three experiments, targets and masking stimuli were briefly flashce while observers visually tracked a moving dot. Masking stimuli were more effective when they appeared to be in the same place as the target but stimulated different parts of the retina than when they stimulated the same parts of the retina but appeared displaced because of of an intervening pursuit eye movement. Visual masking during pursuit eye movements thus depended on the apparent position of the stimuli, not their retinal positions as such, which is in disagreement with previous studies of visual masking during saccadic eye movements. The apparent conflict can be explained in terms of the functional significance of visual masking in tracking and saccardic movements: Retinal position masking after saccadic eye movements may erase previous images, and apparent position masking during pursuit eye movements may make moving targets more visible.


An investigation of the relationship between viewing condition and preference for true and modified linear perspective and adults. In four experiments, pictures varying in degree of perspective convergence from linear to parallel were observed under the following conditions: at an arbitrary station point, at correct station points, and with unconstrained view. Adults were asked to rank the pictures from the most to least natural and realistic-looking picture or from the most to the least accurate drawing. Subjects nearly always chose the parallel perspective pictures as most preferred and the linear perspective pictures as least preferred. Intermediate degrees of convergence were ranked accordingly. Results were interpreted in light of an argument for a pictorial station poing independent of the correct center of projection for a picture. Since this station point was calculated to be at a distance at least 10 times as great as the object is large, its assumption for pictorial viewing was termed the "Zoom "effect.


Mental transformations and visual comparison processes: effects of complexity and similarity. Subjects were required to discriminate previously learned "standard" versions of angular shapes from randomly perturbed "distractor" versions that varied in similarity to the standard. Advance information concerning the identity and the orientation of the test form was provided. Subjects were instructed to prepare for the presentation of the test form by mentally rotating an internal representation of the designated standard form (identity cue) into the designated orientation. The time needed to prepare for the presentation of the test form increased linearly with the angular departure of the indicated orientation from a previously learned position. This finding suggests that, in accordance with instructions, subjects performed a mental rotation in preparing for the upcoming test shape. Rate of preparation was not affected by the complexity of the standard form presented as the identity cue. DIscriminative departure of the test form presented as the identity cue. Discriminative reaction time was not affected by either test-form complexity or angular departure of the test form from the learned orientation. In addition, striking individual differences in the pattern of discriminative reaction times were found. The implications of these results for (a) the nature of the processes and representations underlying the mental rotation task and (b) the nature of visual comparison processes are discussed.


Mental rotation by the blind: does mental rotation depend on visual imagery? Congentially blind adventitiously blind, and blindfolded sighted adults made same-different judgments of pairs of tactile forms. Two forms were presented in the same orientation, or one form differed from the other by a clockwise rotation of 30 degrees, 60 degrees, 120 degrees, or 150 degrees. Like the reaction times for the sighted and the adventitiously blind, reaction times for the congenitally blind increased as a linear function of angular discrepancy between stimuli, suggesting that the congentially blind, like the sighted and adventitiously blind, mentally rotated one form into congruence with the other to make judging easier. Corroboration of the mental rotation inference came from subjects' introspective reports. Inasmuch as the congenitally blind presumably do not have the ability to visually represent form, the present results suggest that mental rotation does not depend upon visual imagery. Thus, with respect to current speculation as to whether visual imagery is a necessary component of mental rotation, the present findings suggest that it is not.


Familiarity of background characters in visual scanning. It is much easier to look for an unfamiliar character (upsidedown A) embedded among familiar ones than to look for a familiar character (A) among unfamiliar ones. Furthermore, the nature of the background seems more important to performance than the nature of the target. The basic experiments involved showing subjects a matrix with nine characters. On target-present trials, eight of the characters were background items and one character was a target item. On target-absent trials, all nine matrix positions were filled by background characters. The types of unfamiliar characters used were rotated English letters, partial letters, and Gibson figures. The familiar characters were upright English letters or digits. Search was easier through familiar backgrounds than through unfamiliar backgrounds with all of the character types used and whether measuring speed or accuracy.


Persistence of a pitch-segregating echoic memory. Auditory stimuli were computer generated in order to measure the persistence of echoic memory. The stimuli consisted of 18 bursts (lasting 307 msec) of six equal-amplitued dichotic tones (frequencies: 392, 440, 494, 523, 587, and 659 Hz), each having a different interaural time disparity. For each stimulus a canonical distribution of interaural time disparities was defined. Five of the interaural time disparities in each burst were equal to canonical disparities for that stimulus; the sixth was not. The deviant tones in successive bursts constituted a musical scale. These deviant tones were perceptually segregated when the interburst interval was short, even though individual bursts sounded like noise when played separately. The interburst intervals for which five subjects could identify with 71% accuracy whether the scale was ascending or descending (obtained by an adaptive psychophysical procedure) averaged about 1 sec. This figure represents a lower bound on the average half-life of echoic memory. A sixth subject performed perfectly even with an inter burst interval of 9.7 sec. Two further experiments were carried out with this subject to support the claim that his performance was due to echoic memory.


How the listener integrates the components of speaking rate. The rate of speaking in words per minute is a function of three independent variables, namely, articulation rate and the number and durations of pauses. The present study varies each of these components separately in a factorial design in order to determine how the listener combines them into a global impression of speech rate. A model was obtained by direct scaling and linear regression that accounts reasonably well for the estimates of apparent rate obtained in this and several other studies. It provides for a trading relation between articulation rate and pause rate in which the former is much more influential in determining the listener's perception of speech rate.


Stream segregation and the illusion of overlap. When two different sounds continuously alternate at high speed, they segregate into two perceptual streams. The present article shows that this segregation produces a loss of information regarding the sequential relations of the sounds so that they seem perceptually to be overlapped in time. The segregation (and its contribution to perceived overlap) is shown to increase with the perceptual difference between the sounds. The mapping from perceptual difference to perceived overlap is not simple, however, since perceived overlap can also be affected by "perceived auditory continuity," another perceptual effect that responds differently to the perceptual difference between the two sounds.


Allocation of attention during visual word recognition. A dual-task paradigm was used to assess attentional processing demands during visual word recognition. By manipulating the difficulty of each task, it is argued that the procedure estimates the attention demands of the memory-access component of word recognition. Specifically, the the complexity of the secondary task was varied from a simple reaction time task to a choice reaction time task, and the difficulty of a lexical decision (word vs. nonword) primary task was varied by manipulating word frequency. A comparison of the effect of secondary task complexity across levels of word frequency showed that the difference between the two secondary tasks was larger for low-frequency words than for high-frequency words. This result, supported by other characteristics of the data, suggests that the memory-access processing in one type of word recognition task does demand attention.


Sequential effects in two-choice reaction time: automatic facilitation or subjective expectancy? A repetition effect is said to occur in a two-choice reaction time (RT) task when the RT for a repeated signal or response is faster than the RT for a new signal or response. An alternation effect is said to occur when the RT for a new signal or response is faster than for a repeated signal or response. A change from a repetition effect to an alternation effect was found across three response-stimulus intervals ranging from 50 msec to 2,000 msec. An analysis was also carried out of the higher-order sequential effects. Differences were found between those obtained from a repetition effect and those obtained from an alternation effect, suggesting that different factors operate in producing them. Two further experiments examined the roles of subjective expectancy and an automatic facilitation in determining these effects. Results suggested that while subjective expectancy operates at all response-stimulus intervals, an automatic facilitation operates only at short intervals.


Decision theory analysis of response latencies in vigilance. In two separate experiments, the latencies associated with all four categories of response (correct detections, false alarms, correct rejections, and omissions) were recorded during the performance of a 45-min. visual monitoring task. In the first experiment, concerned primarily with criterion changes in vigilance, signal probability was manipulated. The second experiment was concerned with sensitivity changes resulting from changes in event rate. In the first experiment, latencies associated with correct detections and false alarms increased, whereas those associated with correct rejections and omission errors decreased, with an increase in criterion. In the second experiment, a reduction in sensitivity associated with an increased event rate exerted significant and opposing effects on latencies of responses to signals (correct detections and omissions) while leaving the latencies of responses to nonsignals (correct rejections and false alarms) unchanged. In both experiments, it was observed that while the latencies associated with positive responses increased with time on task, the latencies of negative responses decreased with time. These results are consistent with the predictions of a decision theory model for response latency extended from signal detection theory, which assumes an inverse relation between response latency and distance from the criterion; A decision theory analysis thus enables the interpretation of both detectability and latency measures of vigilance performance within the same theoretical framework.


Relation between programming time and duration of the response being programmed. When the nature of motor response is varied, holding the number of alternative responses constant, differences in choice reaction time can be attributed to differences in response programming time. The present experiments suggest that although changes in response duration are not necessary to produce small differences in programming time, such response duration changes may be a sufficient condition for the programming time to change and necessary condition for very large changes in programming time. Implications of this conclusion for theories of response programming are discussed.


A function for the plasmalemma grooves of a fission yeast. Ultrastructural studies on regenerating protoplasts of Schizosaccharomyces pombe show that the spatial differentiation of the plasmalemma into grooves and flat areas is reflected in a functional differentiation in cell-wall synthesis. The grooves are the initial site of production of wall fibrils.


Numerical taxonomy of some yellow-pigmented bacteria isolated from plants. Phenetic data on over 60 heterotrophic, Gram-negative, yellow chromogenic bacteria from plant material were collected and analysed using numerical taxonomic methods. Marker strains representing 42 taxa were included in the analyses. At similarity levels of 80% or above, eight distinct clusters were obtained, the first four of which included yellow chromogens. Custer I contained isolates from green healthy leaves of Agrostis tenuis, Festuca rubra, Holcus lanata, Lolium perenne and Poa pratensis, and clusters 2 and 3 consisted of isolates from Holcus lanata seeds and leaves of P. pratensis respectively. Cluster 4 contained seven subgroups and was equated with the family Enterobacteriaceae. Erwinia herbicola strains from a variety of sources formed a homogeneous subgroup, readily distinguishable from authentic strains of E. amylovora, E. carotovora, other representative erwiniae, and from all other enterobacteria studied. These data emphasize the heterogeneous nature of yellow-pigmented bacteria from plants, and support the inclusion of E. herbicola and other Erwinia species in the Enterobacteriaceae.


Proteolytic activation and inactivation of chitin synthetase from Mucor rouxii. Crude chitin synthetase preparations from the mycelial and yeast forms of Mucor rouxii behaved differently. The mycelial preparations, incubated at 28 degrees C, lost virtually all chitin synthetase activity in a few hours; by contrast, the activity of enzyme preparations from yeast cells increased several fold during similar incubations. These spontaneous changes were probably caused by endogenous protease(s). Seemingly, the chitin synthetase in yeast preparations was present mainly in a latent, 'zymogenic', form that was activated by proteases. In the mycelial preparations, chitin synthetase was present mainly in an active state and was rapidly degraded by endogenous proteolysis. Exogenous proteases accelerated activation and destruction of chitin synthetase; an acid protease from Rhizopus chinensis was the most effective activator. The activation of chitin synthetase was inhibited by a soluble protein in the cell-free extract. Treatment with the detergent Brij 36T stabilized the chitin synthetase of crude preparations against spontaneous changes. Stabilized preparations were rapidly activated by exogenous proteases. The different behaviour of chitin synthetases in crude extracts of mycelium and yeast cells is consistent with, and perhaps partially responsible for, the differences in wall construction between mycelial and yeast forms of M. rouxii.


Cellulolytic enzymes in culture filtrates of Rhizoctonia lamellifera. During growth in a liquid culture containing a single soluble or an insoluble cellulosic carbon source, Rhizoctonia lamellifera released cellulolytic enzymes into the medium. These enzymes were separated by gel filtration and ion-exchange chromatography into seven components, three of high and four of low molecular weight. One of the components had the character of a C1 cellulase. When the components were combined they released more reducing sugars from cellulosic substrates than when used singly.