Neuroendocrine control of reproduction in Crustacea

The neuroendocrine factors synthetized by various regions of the nervous system and which have inhibiting or stimulating effects can control the male and female physiology of malacostraca via sexual hormones and moulting hormone. There are between decapods and peracarids functional homologies but some differences can be noticed as to the localization of these antagonistic neurosecretory systems. The functioning of these systems is regulated by external factors such as the photoperiod and the temperature. The interactions between these different neurohormones, the sexual hormones and the moulting hormone are discussed.     

Histochemical distribution of delta5-3beta- and 17beta-hydroxysteroid dehydrogenases in hamster trophoblast.

The histochemical distribution of delta5-3beta- and 17beta-hydroxysteroid dehydrogenases was demonstrated in hamster trophoblast between Days 8 and 15 of pregnancy. The delta5-3beta-hydroxysteroid dehydrogenase activity in the ectoplacental trophoblast of 8-day embryos was demonstrated by use of delta5-pregnenolone and dehydroepiandrosterone as substrates; between Days 11 and 15, activity was demonstrated in the trophoblastic giant cells of the placenta and in the intra-arterial trophoblast cells when delta5-pregnenolone was the substrate. Between Days 11 and 15, 17beta-hydroxysteroid activity was present in the spongiotrophoblast, labyrinth, placental giant cells and intra-arterial trophoblast cells, as shown by use of testosterone and oestradiol as substrates. Both enzymes were demonstrated in ectopic trophoblast cells, indicating that these activities are autonomous.     

Non enzymatic glycosylation increases platelet aggregating potency of collagen from placenta of diabetic human beings

Pepsin extracted collagen and an acid soluble glycoprotein were purified from placentas of normal and diabetic human beings. Diabetic samples exhibit a significant increase in ketoamine-linked glucose whereas both amino acid and carbohydrate composition were unaffected. This excess non enzymatic condensation of glucose on free amino-groups was found to increase platelet aggregating potency of these proteins independently of any modification in fiber morphology.     

Therapeutic efficiency of spleen or bone marrow CFU in X-irradiated 89Sr marrow-ablated mice.

Experiments were carried out to compare the therapeutic efficiency (TE: number of CFU required to reduce the mortality from 100 to 50 per cent) of spleen or marrow (BM) stem cells (CFU) grafted into lethally irradiated mice (807 rad) which had been previously treated with 89Sr or splenectomized. It was found that during the reconstitution of the haemopoietic organs, the spleen does not provide more than 10 per cent of the functional cells necessary for survival. Besides, the BM-derived CFU growing in 89Sr marrow-ablated mice remain twice as efficient as the spleen-derived ones. Similarly, spleen-derived CFU transplanted into splenectomized mice are half as efficient as BM-derived ones. It may therefore be assumed that haemopoietic stem cells grafted into a foreign microenvironment retain their original kinetics of growth and differentiation during 7 to 10 days after their transplantation.     

Evidence that a collagen-derived nonapeptide is a specific inhibitor of platelet-collagen interaction

The aggregation of platelets by type III collagen is inhibited by the collagen peptide α₁ (III)CB4 and by 3 fragments derived from this peptide. These fragments share a common portion of 9 aminoacids with the sequence [Gly-Lys-Hyp-Gly-Glu-Hyp-Gly-Pro-Lys]. This peptide has been synthetized and its ability to prevent the aggregation of platelets has been studied using various inducers. A marked inhibition of the aggregation by type III collagen was observed, and this response was dose related. The effect was much less pronounced when type I collagen was used. Aggregations by ADP, epinephrin, arachidonic acid, ionophore A 23187 were not altered. The inhibition seems then to be specific for collagen and can be associated to the blocking of platelet membrane sites by this nonapeptide.     

Raman spectra and normal vibrations of dipeptides. II. Glycyl-L-proline

Raman and ir spectra of the glycyl-L -proline (GP) dipeptide were recorded. A normal-coordinate treatment was performed on the basis of the experimental spectra, using a modified Urey-Bradley force field (MUBFF). Cyclic redundancies were eliminated, and those due to the ring methylene groups, particularly distorted in regard to the tetrahedral conformation, were treated. An assignment of the experimental frequencies is proposed on the basis of the normal treatment.     

Correlation between the presence of a bacterial symbiont in oocytes of Parcellio dilatatus petiti, and the sterility of the cross: P.d. petiti male x P.d. dilatatus female]

A symbiotic bacteroid matroclinously transmitted is present in the ovocytes and the follicular cells of the sub-species Porcellio dilatatus petiti of the Saint-Honorat island, as well as in all hybrid females born from a petiti mother. It is absent in the Porfellio dilatatus dilatatus females (population of Poitiers) and this seems to cause the lithality in the periblastula stage -- as a result of abnormal anaphases--of practically all the embryos of the crossing : male petiti x female dilatatus.     

The cold shock response inLactococcus lactis subsp.lactis

The lactic acid bacterium,Lactococcus lactis subsp.lactis IL1403 was subjected to defferent cold temperatures for various times. Physiological experiments showed that this strain had an improved survival capacity in stationary phase as the temperature decreased. Two-dimensional electrophoresis of proteins extracted from cold-temperature exposed cultures showed that a dozen proteins are overexpressed up to threefold compared with exposure at 30°C. Most of these proteins are overexpressed first, temporarily and second, in the first 10 h after the transfer to 8°C. These observations indicate that response to cold stress inL. lactis subsp.lactis is an active phenomenon.