Induced diploid gynogenesis and polyploidy in the ornamental (koi) carp Cyprinus carpio L.
The results of a series of experiments conducted in our laboratory on the ornamental common carp (koi), aimed at optimizing heat-shock chromosome-set manipulation procedures, are described. The timing of heat-shock initiation was expressed in the relative unit of embryological age (τ0) in order to standardize this parameter, the absolute time for heat-shock initiation being calculated from duration of one τ0 at two different pre-treatment water temperatures. Heat shocks were applied within the periods of 0.05–0.60 τ0 and 1.20–2.20 τ0 which, respectively, cover the successive phases of the 2nd meiotic division and the 1st cleavage. The highest production of diploid gynogenetic offspring was observed when heat shocks were initiated at 0.15–0.25 τ0 and at 1.5 τ0, after insemination, corresponding to anaphase of meiosis-II, and metaphase of the 1st cleavage, respectively. Similar results were obtained irrespective of the different pre-treatment water temperatures, thus confirming the possibility of standardizing heat-shock timing by τ0.
Induced diploid gynogenesis and polyploidy in the ornamental (koi) carp, Cyprinus carpio L.
The effects of high- and low-temperature shock treatments, applied at different phases of the 2nd meiotic division within the limits of 0.05–0.60 τ0 (τ0 = relative unit of embryological age) in order to induce gynogenesis in the common carp, were studied. A remarkable difference in the effect of two temperature treatments applied at the same biological age after insemination (expressed in τ0) was revealed. The curves of embryo survival and diploid gynogenetic larva output showed a bimodal response in cold-shocked gynogenetic progenies, with the highest level of diploid larva output at the periods 0.05–0.10 τ0 and 0.30–0.40 τ0 (after insemination), separated by a period of high sensitivity to cold shock (0.15–0.25 τ0). In contrast to this, the curves of embryo survival and diploid gynogenetic larva output showed a single, narrow, peak corresponding to 0.15–0.25 τ0 in heat-shocked gynogenetic progenies. The results obtained are in general accord with those of previous experiments on induced gynogenesis and triploidy in common carp, in which either cold- or heat-shock was used.
On the fractionation of β-lactoglobulin and α-lactalbumin
Abstract Existing methods for the preparation of α-lactalbumin and β-lactoglobulin are examined critically. It is proposed that the most satisfactory method for the preparation of the whey protein fraction from bovine milk is (NH 4 ) 2 SO 4 fractionation. A number of new gentle procedures for the fractionation of the whey proteins are compared with some existing methods. The distribution of total protein at various stages is determined by total Kjeldahl nitrogen and the kind of protein by starch-gel electrophoresis. The effect of variables, such as pH, salt concentration and temperature on the separation of α-lactalbumin and serum albumin from β-lactoglobulin is studied. Differences in the behavior ( e.g. solubility) of genetic variants of β-lactoglobulin are noted. The solubility of each of the major whey proteins, under similar conditions to those used in the fractionation, is compared with its solubility in the whey protein mixture. The understanding gained of factors important in the fractionation is used in recommending new procedures for α-lactalbumin and β-lactoglobulin isolation.