Contribution à la connaisance des Rotifères et des Cladocères de la Région parisienne

Sans résuméStagiaire de Recherches au Centre de Recherches Hydrobiologiques du C.N.R.S.     

Etude au microscope électronique à balayage de la morphologie des mandibules chez les Cladocères marins

The mandibles of the parthenogenetic females of the marine calyptomeran and gymnomeran Cladocera have been examined by means of the scanning electron microscope. These investigations reveal great differences beween Calyptomera and Gymnomera with respectively pulverizing and cutting mechanisms. The appendages of the Gymnomera are morphologically very similar and these species seem able to deal with a wide variety of food.

     

Etude de la reponse à un stress hydrique de quelques varietés de riz pluvial et de riz irrigué

Résumé La transpiration de plants de riz cultivés sur sol en chambre de culture, est suivie en continu pendant une séquence déssèchement-irrigation. Les cycles jouraliers de transpiration sont présentés avant et pendant le stress hydrique. Quatre variétés montrent une augmentation de la transpiration nocturne qui disparait lors du stress hydrique. Il apparait que la régulation stomatique est indépendante du potentiel hydrique du sol jusqu'à une valeur seuil au-delà de laquelle la baisse de transpiration est proportionnelle à la baisse du potentiel hydrique. Cette valuer seuil est plus basse pour les variétés de type irrigué.

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Water stress response for some cultivars of upland- and lowland riceI. Effects on transpiration

Summary The transpiration of rice seedlings grown on soil in a growth chamber was observed during a soil drying/rewetting sequence. The diurnal cycles of transpiration are shown before and during the water stress period. Four cultivars showed an increase of transpiration during the night. This increase disappeared during the water stress period. The stomatal regulation appeared not to depend on the soil water potential until a certain value. Below this soil-water threshold, the decrease of transpiration was proportion to the decrease of water potential. This threshold value is lower for the rain-fed cultivars than for the irrigated cultivars.

     

Sur quelques hyménoptères intervenant dans la biocoenose de ravageurs de l’Artichaut dans le sud-est de la France

Summary No discovery of any parasite ofSphaeroderma rubidium Graell.,Ceratapion carduorum Kirbi, andDepressaria subpropinquella Stain. has been mentioned for France. However considerable collections ofMymaridae obtained on layings ofS. rubidium, show that parasitism may have a part in the limitation of this species. The few parasites of larvae and pupae ofC. carduorum obtained do not seem to have any considerable regulating influence. Although the parasitism of caterpillars ofD. subpropinquella byAngitia is frequent, the latter do not seem to be the essential factor in the evolution of the population of this species. The caterpillars ofChoreutis bjerkandrella thnb. may be used as a refuge by manyHymenoptera in summer, as a consequence of the scarcety ofMicrolepidoptera at a vulnerable stage.      

Influence de la température sur la consommation d'oxygène de quelques larves de Trichopteres

Résumé Dans ce travail, il a été étudié (influence de la température sur la consommation d'oxygène de trois larves de Trichoptères: Polycentropus flavomaculatus Pict., Plectrocnemia conspersa (Curt.), et Limnophilus rhombicus (L.). Les animaux étaient accoutumés à la température 48 heures avant le début des expériences.La consommation d'oxygène de ces trois larves croît avec la température.Cet accroissement n'est pas régulier. Il est nul entre 4° et 10°C. Il est faible entre 10° et 20–22°C. Au delà de 22°C l'augmentation est au contraire brutale. Le métabolisme passe du simple au double. On peut en conclure que ces larves sont bien adaptées à des températures allant de 4° à 22°C les températures supérieures n'étant pas des températures de vie normale.On ne note pas de différence significative entre les courbes des formes d'eau courante ou lotiques (Polycentropus et Plectrocnemia) et celle de la forme d'eau stagnante ou forme lénitique (Limnophilus).A une même température, la consommation d'oxygène présente de grandes variations chez les Polycentropidae, animaux actifs et excitables. Ces variations sont faibles chez Limnophilus rhombicus, larve peu active et peu excitable.

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Summary The influence of temperature on oxygen consumption has been studied for three Caddis-fly larvae: Polycentropus flavomaculatus Pict., Plectrocnemia conspersa (Curt.), Limnophilus rhombicus (L.). The animals were acclimated to each new temperature 48 hours before the beginning of the experiments.The higher the temperature, the more oxygen the three larvae consume, but the increase in oxygen consumption with temperature is not regular. Respiratory metabolism is constant between 4 and 10°C. It increases slightly within the 10 to 20°C-range. Above 22°C, the increase becomes quite sharp and often twofold.These larvae are well adapted to the 4–22°C temperature range, whereas higher temperature may be considered as abnormal for them.No significative difference was found between the metabolism-temperature-curves for running-water species (Polycentropus and Plectrocnemia) and for a stagnant-water species (Limnophilus).The oxygen consumption of Polycentropidae varies greatly within the same level of temperature. The animals are active and excitable. The oxygen consumption of Limnophilus varies much less, Limnophilus being less active and less excitable.

     

Le role des “sphagnetalia” dans la vie des tourbières des Hautes-Fagnes

Sans résuméReçu par la rédaction la 1.X.1953.     

Action de la «densonucléose» de Lépidoptères sur les mammifères

Summary The virus of Densonucleosis ofGalleria mellonella (Lepidoptera) is not virulent for mice and rabbits by inoculation and by feeding. Newly born mice are not contamined by intracerebral inoculation. These data are important for comparison of this virus with some Arthropod born viruses and for biological control.      

Activités de quelques enzymes associés à la conidiogenèse du Neurospora crassa

Summary Enzyme activities have been measured and compared at several stages of the development of Neurospora crassa i.e. from free conidia (inoculum) to conidiated mycelia grown on sucrose versus acetate (poor versus highly conidiogenous) media.Glucose-6-phosphate dehydrogenase (G-6-PDH) and NADP nucleotidase (NADPase) show inverse activity-time curves, both on sucrose and acetate media. G-6-PDH has its higher activity at the preconidiating stage while NADPase progressively increases to reach its maximal value in the mature conidia.Malate dehydrogenase (MDH) has a higher activity in extracts from acetate compared to sucrose cultures; in both conditions, maximal MDH activity corresponds with the initiation of conidiation. Malate synthetase (MS) has a delayed activity which is much higher in acetate extracts.Succinate dehydrogenase (SDH) is more active in sucrose than acetate extract with a sharp activity peak just preceding conidiation proper.Isozymes of G-6-PDH and MDH, as well as total soluble proteins from extracts of sucrose versus acetate cultures have been compared after their separation on polyacrylamide columns.     

Notes taxinomiques sur quelques Rotifères planctoniques

Résumé Les caractères spécifiques des différentes espèces appartenant aux genres Keratella, Polyarthra, Synchaeta, Filinia, Conochiloides, Conochilus sont discutés en fonction des observations effectuées par l'auteur dans les collections d'eau de la région parisienne.

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Summary The specific characters of the different species from the genus Keratella, Polyarthra, Synchaeta, Filinia, Conochiloides, Conochilus are discussed according to the observations made by the author in the water collections of the parisian region.

     

Variations saisonnières de la production primaire dans les eaux de surface de la rivière du Saguenay

Experiments of primary production were carried out at weekly intervals in the surface waters at one station (maximum depth of 20 m) in the Saguenay River, near Chicoutimi, during May–December 1978. The photic zone was very thin (maximum depth of 2 m). Phosphates are very low during the season sampling (maximum of 0.1 µat-g.^–1). Maximum of production rates and biomass are respectively 3.5 mg C.m^–3.h^–1 and 3.7 mg.m^–3. The river receives both industrial and urban runoff. Trace metals (Mercury, Copper, Lead, and Iron) seemed to be one of the important limiting factors for phytoplankton growth.

     

'Activité cytokinine' de quelques dérivés analogues: isostères azotes et isomeres de la triacanthine

Eighteen amino purines have been synthesized and their phytohormonal properties have been studied by means of the tobacco-pith, pea-bud and Amaranthus tests. Only three compounds have been found active, all of them having their purine nucleus substituted at the 6-position. Activity has been observed, for the first time, in nitrogen-isosteric derivatives of N-(γ,γ-dimethyl-allyl)adenine. However, the cytokinin activities of the 3 derivatives are found to be lower than those of kinetin, N-benzyladenine and N-(γ,γ-dimethyl-allyl)adenine.     

Caractères physico-chimiques des choanoleucocytes de quelques Invertébrés

Sans résumé