Effets des sucres sur le comportement alimentaire de Lambdina fiscellaria

Quatorze sucres (D-arabinose, L-arabinose, fructose, galactose, glucose, maltose, manose, mélézitose, mélibiose, raffinose, rhammose, sucrose, tréhalose, xylose) ont été étudiés en fonction de leur consommation, à différentes concentrations, par les stades IV et V de Lambdina fiscellaria fiscellaria Guén. Les indices de consommation mesurés varient avec la concentration de la solution sucrée, à l'exception du D-arabinose qui induit une consommation comparable (t_0.05) à 0.5 M, 0.1 M et 0.02 M et ce, pour les 2 stades. Une diminution de la consommation est parallèle à une diminution de la concentration des solutions de galactose et de xylose pour le stade IV, et de sucrose et xylose pour le stade V. La prise alimentaire la plus élevée pour le stade IV est mesurée avec le sucrose aux 3 molarités, tandis que celle du stade V est notée avec le sucrose et le glucose. L'écart entre les indices de comsommation des sucres diminue avec une baisse de la concentration de la solution sucrée pour les 2 stades, créant ainsi de nombreuses interrelations entre les sucres.

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Summary Fourteen sugars (D-arabionose, L-arabinose, fructose, galactose, glucose, maltose, mannose, melezitose, melibiose, raffinose, rhamnose, sucrose, trehalose, xylose) at different concentrations were studied with regard to consumption, by the fourth and fifth larval instars of Lambdina fiscellaria fiscellaria Guén. The consumption indices vary with the concentration of sugars, except for D-arabinose which induces comparable consumptions (t_0.05) at 0.5 M, 0.1 M and 0.02 M in both larval instars. A reduction in the consumption of sugars parallels decreases of galactose and xylose concentrations for the fourth larval instar, and sucrose and xylose concentrations for the fifth larval instar. According to food intake data, the fourth larval instar prefers sucrose while the fifth larval instar shows increased glucose responses, and even prefers glucose at 0.02 M. The differences among sugar consumption indices decrease when the sugar concentration is reduced.

     

Effets de la reserpine sur la proteinemie de l'hemolymphe et le developpement ovocytaire chez Schistocerca gregaria forsk

Résumé Des femelles grégaires de Schistocerca gregaria sont injectées avec des concentrations de réserpine de 10 ou 300 g/g de poids frais aux jours 1 ou 8 après la mue imaginale. Au cours du premier cycle ovarien, la réserpine (300 g/g) ralentit significativement la croissance prévitellogénique de l'ovocyte ainsi que le dépôt du vitellus dans l'ovocyte terminal. L'augmentation habituelle de la protéinémie de l'hémolymphe, suite à la mue adulte, est retardée chez les femelles traitées au jour 1. Cependant, lorsque le traitement a lieu au jour 8, la concentration protéique antérieurement atteinte est conservée et demeure équivalente à celle des femelles témoins. Le volume d'hémolymphe ne semble pas modifié par l'administration du neuroleptique. Chez les femelles isolées au jour 1 ou 8, la vitesse de dépôt du vitellus dans les ovocytes terminaux diminue; la croissance prévitellogénique et la protéinémie ne sont pas affectées.La consommation de nourriture, mesurée par la production fécale, demeure généralement moindre chez les insectes réserpinés. Les résultats sont discutés en considérant le rôle des différentes parties du système neuro-endocrinien sur l'ovogénèse.

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Summary Reserpine at two concentrations (10 and 300 g/g) was injected into the body cavity of crowded Schistocerca gregaria females 1 or 8 days after the adult molt. During the first ovarian cycle, both previtellogenic oöcyte growth and vitellogenesis were significantly reduced by the 300 g/g treatment. In females treated on day 1, haemolymph protein concentration increased more slowly than in controls, whereas treatment on day 8 did not affect the protein level. Blood volume did not differ in treated and control insects. In females isolated on day 1 or 8, yolk deposition in terminal oöcytes was reduced, whereas previtellogenic oöcyte growth and haemolymph protein concentration were not affected.Food intake as measured by faeces production was generally lower in treated locusts in comparison with the controls. Results are discussed with regard to the rôle of the neuroendocrine system in controlling oögenesis.

     

Influence des conditions préalables de culture sur le métabolisme de l'éthanol et de l'acide acétique par la levure

Résumé Le milieu de croissance préalable semble intervenir sur l'aptitude des levures à métaboliser l'éthanol et l'acide acétique. Dans certains cas, les deux substrats activent l'oxydation des réserves. Ce phénomène se produit avec des levures cultivées sur milieu synthétique contenant du glucose 2% ou de l'éthanol 1%. Il ne se produit pas avec des levures cultivées sur ce même milieu synthétique contenant du glucose 0,5%. Il ne peut cependant être expliqué, ni par une richesse supérieure des cellules en réserves glucidiques, ni par un déséquilibre alimentaire, ni par une différence d'activité respiratoire.

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Influence of culture conditions on ethanol and acetic acid metabolism of yeast

Summary The medium in which yeasts are grown seems to modify their ability to metabolize ethanol and acetic acid. In certain cases, the two substrates activate the oxidation of reserves. The phenomenon is observed with yeasts grown on synthetic medium with glucose 2% or ethanol 1%. It is never observed with yeasts grown on the same medium with glucose 0.5%. It cannot be explained either by an elevated cellular level of carbohydrate reserves, by a nutritional imbalance, or by a difference in respiratory activity.

     

Effets à court et à long termes de la cure de varicocèle sur les caractéristiques spermatiques

The authors studied the sperm features of 122 patients, before and 3 months, 6 months, 9 months and 12 months after varicocele repair, in order to define the sperm profiles of these patients and to study effects of this treatment on these profiles. Patients with varicocele generally present severe asthenozoospermia. Of the 122 patients studied: ?18% were extreme oligozoospermic, ?26% were severe oligozoospermic, ?18% were moderate oligozoospermic, ?38% were normozoospermic. Varicocele repair does not influence the volume of semen, the vitality of spermatozoa, their survival, their rate of abnormal shapes, or male genital tract markers, but significantly improves sperm counts and mobility, in men with extreme or severe oligozoospermia. This type of treatment is generally indicated in patients with extreme or severe oligoasthenozoospermia in order to obtain a natural pregnancy, or at least to increase the success of medically assisted procreation techniques.     

Effets d'un régulateur de croissance d'insectes,le fénoxycarbe,sur la diapause du psylle du poirier Cacopsylla pyri

The nature of the responses of the sheep blowfly Lucilia sericata Meigen (Diptera: Calliphoridae) to carrion odours and carbon dioxide were examined in a windtunnel in the laboratory and the attractiveness of carrion-bait was examined in the field. In the wind tunnel, gravid 9-day-old females increased both the number and duration of their flights, in response to carrion odours. In addition, linear velocity was reduced and the sinuosity of flight increased in the presence of these odours. With 3-day-old females, the response to carrrion odour depended on previous exposure to proteinaceous material. Protein deprived females showed kinetic responses to carrionodour which were similar to those of gravid females. No such changes were observed in protein-fed females. No responses to CO₂ were observed. In the field, the importance of olfactory cues in bait location was demonstrated by the absence of L. sericata from sticky targets lacking an odour bait. Increased bait concentration did not affect the age, sex ratio or ratio of L. sericata to other Lucilia spp. caught, but did increase the numbers caught. Analysis of the reproductive status of females caught, indicated that a greater number of gravid females were caught than expected, while a lower number of females in the final stages of vitellogenesis were caught than expected. The results show that the responses of L. sericata to odours are complex, and are dependent on both exogenous and endogenous stimuli, the latter including the stage of ovarian development.     

Effets de la fumitoxine A sur le tissu foliaire de Pisum sativum L.

Etiolated pea seedlings are treated with fumitoxin A, a mycotoxin produced by Aspergillus fumigatus Fres. The effects observed on the greening process relate to the production of chlorophyll and fatty acid biosynthesis. The effects vary in relation to the dose of toxin used. With high doses, fumitoxin A gives rise to a diminution of chlorophyll level and an inhibition of fatty acid biosynthesis. Lower doses cause a significant augmentation of chlorophyll level and at the same time, an acceleration of polyunsaturated fatty acid biosynthesis.     

Influence de l'intensité et de la longueur d'onde de la lumière sur le rendement des radicaux libres dans les semences de tomate et de carotte

Influence of light intensity and wavelength on the yield of free radicals in seeds of tomato and carrot.
Seeds of tomato ( Lycopersicum esculentum L. cv. Gribovsky-1180) and carrot ( Daucus carota L. cv. Santanet) were irradiated by continuous light of different wavelengths (white, blue, green, red, far-red and He-Ne laser) and different power density. Free radical output was measured using Electron Spin Resonance spectra (ESR). The dependence of the content of free radicals (FR) on the light power density was established. The yield of FR in the seeds irradiated with monochromatic light of the same power density was inversely proportional to the wavelength. The ESR spectra showed maximum absolute number of FR for white light. Successive irradiations gave cumulative effects on the output of free radicals in both directions: increase by the action of white light and decrease by the action of red and far-red light. The contact of irradiated seeds with steam decreased the amount of FR.     

Effets des marées sur la variation circadienne de la capacité photosynthétique du phytoplancton de l'estuaire du saint-laurent

The photosynthetic capacity of phytoplankton was measured at an anchor station in the Middle Estuary of the St Lawrence, over a period of 120 h. Hourly incubations were made in constant light conditions, under three different colour filters of 3, 4 and 23 W · m^?2. Differences in the oscillations of the photosynthetic capacities were observed in relation to the tidal regime. During spring tide, variations in the photosynthetic capacity are circadian, whereas a tidal pattern was also observed during the neap tide period. Differences in the patterns of photosynthetic capacity were probably due to changes in the gradients of physical factors and to the physiological state of phytoplankton relative to these gradients. The circadian rhythms appeared to be endogenous since they were apparent at non-saturating light intensities and since the photosynthetic potential (U_max) changed during the day.     

Influences de la castration et du propionate de testosterone sur le comportement des rats conditionnes par paires

Four groups of 10 male rats (Group A: normal rats, Group B: castrated rats, Group C: castrated rats + 1 mg P.T./day, Group D: castrated rats + 1 dose of 50 mg/kg of P.T. cyclohexane) were avoidance conditioned during nine sessions of 50 trials. They were conditioned individually during sessions 4, 5 and 6 and by pairs during sessions 1, 2, 3, 7, 8 and 9. During these last sessions, all groups presented a low level of acquisition and aggressive behaviour. These phenomena were worsened in the castrated rats whose performances stayed low even when they were conditioned individually. On the other hand, the frequency of their aggressive behaviour was often higher than that of the other groups. The injection of P.T. cyclo-hexane improves the performance of the castrated animals but does not entirely compensate for the differences between control and experimental rats.     

Fixation de l'acide phosphorique sur le calcaire des sols

Conclusion Les expériences ci-dessus nous montrent que le P₂O₅ des solutions du sol à faible concentration se fixent sur les grains calcaire de la terre arable non par précipitation, mais par un phénomène d'adsorption.L'acide phosphorique ainsi fixé peut repasser en solution par le phénomène inverse de désorption pour être mis a la disposition des plantes lorsque le titre de la solution du sol en P₂O₅ s'appauvrit.Lorsqu'on ajoute au sol des engrais phosphates, la concentration en P₂O₅ autour des grains d'engrais peut ëtre suffisamment élevée pour qu'il y ait précipitation de phosphate gélatineux autour des granules d'engrais.Mais ces précipités se redissolvent au moins partiellement dans les solutions du sol et se fixent sur les grains calcaire suivant le processus que nous venons d'indiquer.     

Cinétique de la rhizogenèse adaptative à la sécheresse. Relation avec I'évolution des paramètres hydriques et morphologiques chez le Sinapis alba, à deux niveaux d'énergie lumineuse

Kinetics of adaptive drought rhizogenesis, as related to growth and water deficits in Sinapis alba, at two irradiance levels .
The rhizogenic activity in Sinapis alba L., subjected to progressively increasing water deficit during growth, shows a sigmoidal pattern of kinetics with three phases: initiation or latent phase, rapid exponential increase, and stationary phase. This pattern remains unchanged if the level of irradiance during growth is reduced. The same number of short tuberized roots is obtained as under high irradiance, although initiation of rhizogenesis appears to be delayed by a few days. However, this delay is not observed if the rhizogenesis is analyzed as a function of the water potential of aerial organs or as a function of the soil water deficit. Since the rate of dehydration depends upon the evaporative demand, which is modulated by high or low irradiance, drought rhizogenesis seems to be directly related to water deficits in the soil-plant system. The onset of drought rhizogenesis, starting at the end of the growth period of the aerial organs, appears concomitant with the transpiration decline which is induced by water stress at both irradiance levels.