Chemotaxis of larval soybean cyst nematode,Heterodera glycines Race 3, to root leachates and ions
Second-stage larvae of the soybean cyst nematodeHeterodera glycines Race 3 were attracted in an in vitro bioassay to pooled leachates of soybean roots that were expressed as root gram-hours (1 g of root/hr/vol). Their responses were dosage dependent with maximal attraction to a 5 root g-hr/ml source. Optimal bioassay conditions used 24 hr for gradient formation and 1.5 hr for larval movement. Individual plants produced leachate with little variation in biological activity. Production was constant for five days of preparation. The attractive activity of root leachate declined with storage at 4 °C and heating over 30 °C, but loss of activity was reduced by freezing. Extraction and Sep-Pak fractionation indicated that the attractions(s) was water-soluble. Larvae were attracted also to several ionic solutions.
Note Préliminaire Sur Le Déplacement De Hemicycliophora Paradoxa Luc (Nematoda - Criconematidae) Dans Le Sol
L'auteur etudie le deplacement vertical de Hemicycliophora paradoxa hors d'une terre infestee venant de culture de mil (Pennisetum typhoides) en pot, vers de la terre sterilisee ou vers de la terre de rhizosphere de mil mise en contact dans des tubes de plexiglas. Les resultats des diverses experiences montrent que le deplacement vers la terre sterilisee est faible et est augmente par un courant ascendant d'humidification (H = 5 - 20 %). Si l'on remplace la terre sterilisee par de la terre de rhizosphere de mil les taux de deplacement montent encore et avec humidification deviennent les plus hauts. La culture du mil, plante-hote, a donc apporte au sol un ou des facteurs favorisant les deplacements de H. paradoxa. D'autres series experimentales ont montre que ce ou ces facteurs sont adsorbes sur la fraction argileuse du sol, sont thermolabiles, resistants a la dessication, remanents dans le sol apres la culture du mil et diffusent a des distances assez grandes de son systeme radiculaire aussi bien horizontalement que verticalement. D'autre part, la culture de differentes Legumineuses, plantes non hotes, ne semble apporter au sol aucun facteur favorisant. Enfin la culture du mil apporterait au sol, en sus du ou des facteurs favorisants, un ou des facteurs hydrosolubles, defavorisant le deplacement.
Instrumentation and Automated Photometric Titration Procedure for Total Acidity Determination in Red Wine Employing a Multicommuted Flow System
An automated procedure for photometric titration of red wine and associated instrumentation is described. The procedure was based on the flow-batch approach implemented employing multicommutation. The photometric detection was carried out using a homemade LED-based photometer. The mixing device, LED, and photodetector were attached to the titration chamber in order to form a compact and small-sized unit. The flow system comprised an automatic injector and three-way solenoid valves, which were controlled by a microcomputer through an electronic interface card. The software, written in Quick BASIC 4.5, was designed with abilities to accomplish all steps of the titration procedure including data acquisition and real-time processing to decide about the course of titration in the following step and so forth, until the titration endpoint was reached. The usefulness of the proposed titration system was demonstrated by analyzing red wine samples. When results were compared with those obtained using the AOAC reference method, no significant difference was observed at the 95% confidence level. A relative standard deviation of ca  2% (n=9 ) was obtained when processing a typical red wine sample containing 7.3 gl -1 total acidity expressed as tartaric acid.