Latency of Botrytis cinerea Pers.: Fr. and Biochemical Studies During Growth and Ripening of Two Grape Berry Cultivars, Respectively Susceptible and Resistant to Grey Mould

Latency and development of Botrytis cinerea were assessed under field conditions and after artificial inoculation of two grape varieties, Gamay (susceptible) and Gamaret (resistant). When the percentage of latent Botrytis was the same for both varieties, severity of visible grey mould remained very low in Gamaret berries, while Gamay clusters were destroyed by the disease to a high percentage. Some biochemical parameters were measured in berries, such as constitutive and induced anti‐fungal compounds, polymeric proanthocyanidins and lipid peroxidation products as markers of senescence. Differences were observed in polymeric proanthocyanidins (PPRA) of Gamaret compared with those of Gamay. Concentration and mean degree of polymerization (mDP) of PPRA were always higher in the berries of the resistant variety. The inhibitory effect of Gamaret PPRA on enzyme activity remained until harvest whereas Gamay PPRA lost their inhibitory activity at the beginning of véraison. Based on these results, resistance to B. cinerea seems to be linked to the maintainance of the fungus in its latent form in berries, mainly due to the ability of Gamaret PPRA to inhibit macerating fungal enzyme activities.     

The expression of the sIgD isotype in wild-derived mice

IgD and IgM are concomitantly expressed on the surface of most mouse B lymphocytes and both molecules serve as receptor for antigen. In this communication we report that in contrast to IgM, which is expressed in a constant manner on the surface of spleen B lymphocytes of different laboratory and wild-derived mice, IgD expression is variable among the spleen cells of wild-derived mice. SPE, SEI, and SFM mice belonging to the Mus 3 subgroup show a fluorescence profile characterized by a marked diminution in the population of B lymphocytes expressing the IgD isotype; in addition, these cells have a low sIgD density on their membranes. These findings were confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the iodinated membrane proteins. Polyclonal in vitro activation with lipopolysaccharide increases the frequency of surface IgD (sIgD)-bearing spleen cells and sIgD density in the SPE strain but decreases both the frequency and the density of IgD bearing cells in the BALB/c strain. This result suggests that delta gene expression is regulated differently in SPE and BALB/c mice. In addition, genetic analysis of sIgD expression in (BALB/c X SPE)F1 hybrids suggests that the proportion of sIgD-bearing cells and sIgD density are independently regulated.     

Insect cell density in bioreactor cultures can be estimated from on-line measurements of optical density

Total cell density in growing insect cell suspension cultures was accurately estimated from both off-line and on-line measurements of optical density (OD). The latter measurements were done with an in-situ autoclavable OD sensor. The ability to continuously monitor cell density in insect cell cultures may be useful for the development of a large-scale process for recombinant protein production using baculovirus expression vectors.     

Cytogenetic study in spermatocytes of mice and Chinese hamsters after treatment with isoniazid (INH)

Summary Meiotic chromosomes of spermatocytes from INH-treated male mice and Chinese hamsters were analysed for chromosome aberrations in diakinesis-metaphase I and metaphase II. The experiments were performed in two laboratories while a third laboratory participated in the chromosome evaluation. No enhancement of chromosome aberrations could be observed after acute treatment of early primary spermatocytes or chronic treatment of spermatogonia with INH.     

Staining of glycoproteins in polyacrylamide and agarose gels with fluorescent lectins.

We describe a simple and sensitive method for staining of the carbohydrate moiety of glycoproteins in polyacrylamide or agarose electrophoretic gels. Gels are incubated in a solution of fluorescein-labeled concanavalin A. Following destaining with a neutral buffer, glycoproteins exhibit fluorescence under long-range ultraviolet light. Thus, the glucose/mannose containing β- and γ-chains of human fibrinogen give fluorescent bands, whereas the carbohydrate-free α-chain does not react. Less than 100 ng of hexose bound to fibrinogen β- or γ-chains could be detected. The procedure is suitable for staining of other carbohydrate residues in glycoproteins, which can be recognised by specific agglutinins, as shown by binding of fluorescein-labeled lectins from Ricinus communis to galactose residues of fibrinogen.     

Variations in oxygen consumption of Demidoff's bushbaby (Galago demidovii, lorisidae, primates) in captivity

Summary In captivity,Galago demidovii shows annual variations in oxygen consumption which are independent of daylength cycles. This rhythm is characterized by two periods during which metabolic and sexual activities are increased: a short period in November/December; and a longer period from March to June inclusive. These two periods alternate with periods of decreased metabolic rate, of which the most pronounced extends from July to September. Another point of interest is that the basal metabolism of captive Galagos is 17.5% above the value calculated from its body weight.The physiological cycle observed in captivity is synchronized with climatic variations in Makokou (Gaboon), from where the animals originated: higher metabolic and sexual activities are correlated with rainy seasons. This study suggests that an endogenous rhythm may exist inGalago demidovii.     

Environmental and social determinants of sexual function in the male lesser mouse lemur (Microcebus murinus).

Environmental factors that regulate the sexual activity of male lesser mouse lemurs have been studied experimentally with more than 60 captive animals over an 8-year period. In this nocturnal Malagasy prosimian, variation in day length is the primary factor controlling seasonal sexual activity. Plasma testosterone concentrations were low (= 9 ng/ml) during short days and reached 60 ng/ml during long days (> 12-hour day). This cyclic pattern persists unchanged when artificial photoperiodic rhythms are applied and is not altered by ageing. The timing of puberty is also regulated by photoperiodic changes. Nevertheless, the sexual activity of the male lesser mouse lemur can be dramatically modified by the social environment. In heterosexual groups, behavioural and physiological components of sexual activity are depressed in all males except the dominant one, whose aggressive interactions are always successful. Intermale sexual inhibition was shown to be mediated by chemical cues present in the urine of dominant or isolated males but not in urine of subordinate individuals. The inhibitory signals possess lipophilic properties and are not contingent on the gonadal activity of the urine donor but are linked to adrenocortical activity. By contrast, chemical signals stimulating the reproductive function of all males are found in the urine of females, the presence of which is required for the establishment of clear dominance among grouped males. Endocrine mechanisms underlying intermale sexual inhibition by chemical cues were analysed. Variations in prolactin strongly suggest that olfaction interacts with the photoperiodic regulation of reproductive function, leading to changes in the sensitivity of the negative feedback effect of testosterone on gonadotrophin secretion. Inhibitory or stimulatory effects of chemical signals are discussed in the context of their functional significance for wild populations.     

Thermal behavior and elastic properties of phospholipid bilayers under the effect of a synthetic flavonoid derivative, LEW-10.

We have investigated the effect on phospholipidic bilayers of LEW-10, a synthetic flavonoid, derivative of diosmin. Two optical techniques, Quasi-elastic Light Scattering (QLS) and Fourier Transform Infrared Spectroscopy (FT-IR) were used. The results show that in the presence of LEW-10, the phase transition of the bilayers is lowered and that the elastic modulus is decreased. The FT-IR results indicate interactions in the aqueous interface regions of the bilayers. We also discuss LEW-10 comparatively with another derivative, LEW-7/S1, whose effect has been previously studied.     

What are the consequences of being a downy oak (quercus pubescens) or a holm oak (Q. ilex) for breeding blue tits (Parus caeruleus)?

By comparison with deciduous oaks, the lower yearly production of new leaves in sclerophyllous oaks is hypothesized to have several consequences on animal communities. In particular, the production of arthropod communities that feed upon the leaves should be lower in sclerophyllous than in deciduous oaks, this causing changes in breeding patterns and the demographic balance in insectivorous birds. Studies in both deciduous and sclerophyllous habitats in southern France have shown that: 1) the spring development of new leaves occurs later and more slowly in sclerophyllous than in deciduous oaks, 2) the biomass of caterpillars is much lower in sclerophyllous oak forests, and 3) there is a large variation in life history traits of the Blue Tit depending in which type of habitat they breed. Laying date occurs later and clutch size is lower in sclerophyllous habitats than in deciduous habitats. The evolution of life history traits is discussed according to whether poor sclerophyllous habitats are isolated (e.g. on Corsica) or are parts of landscapes including both habitat types.