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Le précipité (30 000 x g) d'un homogénat de corps gras catalyse la formation d'acide phosphatidique à partir d'α-glycérophosphate-U-14C et de palmityl-CoA. À 25°C et avec des concentrations protéiques entre 10 et 250 mg/ml, la réaction est linéaire pendant 6 min. Le pH optimum est 8.5. Le Km apparent est de 8.3 x 10-3 M pour le palmityl-CoA et de 3.3 x 10-3 M pour le glycérophosphate. Des concentrations supérieures à 40 µM en palmityl-CoA inhibent la réaction. Dans les mêmes conditions, la préparation enzymatique catalyse aussi l'acylation par l'oléyl-CoA. Toutefois, à concentration optimum (10 µM), la quantité d'α-glycérophosphate transformée …
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When these compounds are fed to the larvae, the growth of the latter is retarded depending upon the concentrations. Retardation of larval growth is generally accompanied by reduction in fecundity or egg laying capacity of adults. Three compounds act in altogether different way by retarding larval growth on one hand and by increasing the adult fecundity on other. Experiments are also in progress to investigate the effects of these compounds on fertility and enzyme systems.
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The changes in morphology during insect development that result from endocrine interactions are reflected in changes in the protein constitution of various tissues (Hans Laufer 1963). It has also been shown that several of these proteins possess enzymatic activities. Since the respiratory enzymes undergo outstanding changes in their activity during the course of insect life cycle, the present study was undertaken to characterise some of the dehydrogenating enzymes at different stages of the insect development. The results obtained on malate dehydrogenase as regards to its activity, kinetic properties and electrophoretic pattern at different stages of the life cycle of T. …
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T. confusum DNA has been isolated by the method of Colter et al (1961) which involves repeated extraction of the cells, suspended in buffered 1 M NaCl, with water saturated phenol. The hydrolysate of DNA, obtained by heating the latter in 1N HCl for one hour, was chromatographed on thin-layer DEAE - cellulose (Randerath, 1963) in a solvent system comprising of isobutyric acid, H2O and NH4OH (66:33:1). The ultraviolet spots, corresponding to various bases, were quantitatively estimated and AT/GC ratio was found to approximate a value of 1.4. Certain other properties such as Tm and viscosity measure of T. confusum …
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Smissman et ses collaborateurs (1964) ont récemment démontré la présence de prégnénolone et de progestérone chez la larve de T. confusum. Nous avons pu confirmer ces résultats et nous avons aussi étudié les transformations in vitro que subit la progestérone dans des homogénats d'adultes. Trois milieux d'incubation différents ont été utilisés: a) une solution de tyrode tamponné b) le milieu habituellement employé pour l'étude in vitro des métabolites de la progestérone avec les surrénales c) le milieu employé avec les organes génitaux. Nous avons analysé la fraction inaspoinifiable par chromatographie sur colonnes d'alumine neutre et acide. Nous poursuivons actuellement cette …
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Occurence of a "true" cholinesterase and a "pseudo" cholinesterase, as indicated by substrate specificity, substrate concentration pattern and selective inhibition, has been demonstrated in T. confusum. The variation in the titre of both these enzymes has been shown in relation to various stages in the life cycle of this insect. The effect of different types of stress such as starvation as well as exposure to certain anaesthetics, on the enzymatic activity has also been investigated. Studies on intracellular localization of the enzymes showed that the maximum activity of the two enzymes was located in mitochondria and in microsomes.
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Variations undergone by body weight have been investigated during starvation. Total phosphorus decreases during inanition probably in conformity with the lower metabolic activity. The characteristic feature of starvation is a rise in inorganic phosphorus probably at the expense of several phosphorus compounds ie phospholipids, RNA, etc. DNA shows no principal variation. The values of respiratory quotient indicate a concomitant utilization of fat and carbohydrate during most part of starvation, total nitrogen undergoing no major change.
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L'indispensabilité des deux acides aminés, tryptophane et lysine, dans la nutrition des larves de Tribolium confusum ne fait aucun doute. Nous avons prouvé cette nécessité en utilisant trois protéines incomplètes: la gélatine déficiente en tryptophane, la gliadine déficiente en lysine, la zéine déficiente en tryptophane et en lysine.
