Fitness comparison inPhytoseiulus persimilis strains resistant and susceptible to methidathion

The effect of selection for methidathion resistance on fitness components of aP. persimilis strain was analysed by different means. The resistant strain was compared with the susceptible one from which it was selected. The life history and some parameters essential to the successful use of this species in biological control (voracity, resistance to starvation and drought) were analysed. Methidathion resistance was followed for 6 months under rearing conditions free of insecticide in the resistant and in a mixed strain. The investigations showed that the fitness of resistant mites did not seem altered by methidathion selection. It thus appears possible to increase pesticide resistance in beneficial arthropods without adversely affecting their main fitness components.     

Molecular diagnosis of Duchenne and Becker muscular dystrophies. Current data

Carrier diagnosis and prenatal diagnosis of Duchenne's muscular dystrophy (DMD) and Becker's muscular dystrophy (BMD) has become possible using some twenty RFLPs detected by more than a dozen Xp21 probes that are either intragenic or flanking the disease locus. Results from familial studies on 88 DMD and BM families stress important considerations concerning a priori and final risks, individuals necessary for the identification of the phase, and the different strategies that can be applied, regardless of whether the study concerns an on-going pregnancy or a carrier-status determination, and whether the patient is at high or low risk. Finally, multiple sources of difficulties in interpreting the results depend on a) the occurrence of new mutations that must be traced; b) the existence of meiotic recombination; c) the necessity, in some instances, of relying upon the sole identification of the paternal X. These considerations emphasize the characteristics and the important limitations of this type of methodology.     

Variation of the sterols from Kluyveromyces lactis and from a resistant mutant by culture in the presence of sublethal doses of amphotericin B

A mutant strain of Kluyveromyces lactis resistant to amphotericin B and weakly to nystatin has been isolated from subcultures of the wild strain grown in the presence of sublethal doses of amphotericin B. The mutant and the wild strain were equally sensitive to pimaricin, filipin, and candicidin. The efficacy of fungizone was very low. In comparison with the wild strain the level of sterols was two times lower in the resistant strain but the composition of these sterols was about the same in the two strains. The action of sublethal doses of amphotericin B on the composition of the sterols was the same in these two yeasts and brought a 40% decrease of the total sterol level and a modification in their distribution. This variation cannot fully explain the resistance of the yeast but it may be associated to other changes of the membranes.     

Sélection artificielle pour la résistance au méthidathion chezPhytoseiulus persimilis A. H.

Résumé La toxicité du méthidathion a été mesurée sur 7 souches dePhytoseiulus persimilis provenant de collections de laboratoire, d'unités de production ou du terrain. Les résultats obtenus se sont avérés être très variables: la CL50 de la souche la plus résistante est 100 fois plus élevée que celle de la souche la plus sensible. Chaque souche a ensuite été sélectionnée pour la résistance à cet insecticide; toutes les souches ont répondu à la sélection et ont atteint des niveaux de résistance similaires. Elles ont ensuite été mélangées, à nouveau sélectionnées pour la résistance au méthidathion et à d'autres insecticides et utilisées dans les programmes de lutte intégrée. La résistance a pu ainsi être légèrement augmentée et la souche obtenue, bien qu'encore affectée par le méthidathion sur le terrain, n'est plus complètement éliminée par les traitements et est moins sensible aux résidus présents sur les feuilles.      

Striated ciliary root-golgi association in branchial crown epithelial cells ofOwenia. Visualization of Ca2+-binding sites and ATPase activities

Summary Striated Ciliary Roots (SCRs), about 3 m long, are attached to the basal bodies of branchial crown ciliated epithelial cells ofOwenia. These SCRs appear to consist of 5–7-nm diameter filaments organized in a cross-striation pattern with an apparent variable periodicity of 50 to 80 nm. The most exciting observation emerging from this study is the constant and conspicuous close spatial relationship between SCRs and fairly well developed Golgi apparatus. By enhancing contrast and preservation of cell components, the OsFeCN postfixation-staining of material prefixed in glutaraldehyde in the presence of calcium has revealed some fine-structural details within the SCR-Golgi Association. By means of the calcium precipitation method, with antimonate or oxalate in conjunction with X-ray microanalysis, we have identified calcium within SCR dark bands and SCR-associated Golgi bodies. The ability to bind calcium makes the Golgi apparatus a likely candidate for Ca²⁺ regulation of putative contraction of the SCRs and/or ciliary motility. The slight period variability measured in the SCRs and cytochemical localization of Mg²⁺, Ca²⁺-dependent ATPase activities associated with cross striations support the view that theOwenia SCRs may be contractile organelles.The striking and specific close structural association between the Golgi apparatus and the SCR showing Ca²⁺-binding capabilities suggests that some sort of Ca²⁺-mediated functional relationship between these organelles may exist.Abbreviations SCR striated ciliary root - OsFeCN method osmium tetroxide-ferricyanide method - EDTA ethylenediamine tetraacetic acid - EGTA ethyleneglycol-bis-(-aminoethyl ether) N,N-tetraacetic acid - ATP adenosine 5-triphosphoric acid - ATPase adenosine triphosphatase - ASW artificial sea-water     

The function of type IV collagen during Drosophila embryogenesis

A collagen gene (Dcg1) was characterized in Drosophila melanogaster and shown to encode a peptide related to vertebrate basement membrane type IV collagen chains. To study the function of type IV collagen during Drosophila development, we transformed flies with a partially truncated Dcg1 gene under the control of a heat-shock promotor. This construct induced synthesis of shortened pro- chains which associated with normal ones and thereby caused degradation of the shortened and normal pro- chains through a process called pro-collagen suicide. A large proportion of embryos expressing the transgene developed a phenotype exhibiting absence or partial retraction of the germ band with defects in nerve cord condensation and dorsal closure. Together these results indicated that, during embryogenesis, type IV collagen was an essential guiding factor for cell-matrix interactions in morphogenetic events.     

Comparison of direct esterification and transesterification of fructose by Candida antartica lipase

Fructose oleates synthesis was performed in a batch reactor by trans- or direct esterification. An immobilized lipase from Candida antartica was used. When a solvent was used, 65% and 46% of conversion of fructose were obtained by transesterification and direct esterification, respectively. These two reactions were also compared in a solvent-free melt. Both in molten media and with cosolvent, two isomeric forms of fructose oleates were produced.     

Effets de l'irradiation X sur les chenilles de Bombyx mori dans diverses conditions d'alimentation et de jeune

Nous modifions le cycle nutritionnel des chenilles de Bombyx mori, durant les premières 24 heures des deux premiers âges larvaires, avant ou après irradiation X. La chenille avant toute alimentation est très radiorésistante, le jeûne ne modifie pas cette radiorésistance. Suivant le moment du cycle physiologique (lorsque celui-ci est enclenché) où le jeûne est imposé, il diminuera ou augmentera la radiosensibilité des chenilles.