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.

     

Effet de la température sur la structure du fibrinogène

The variation of temperature from 5 to 37° produces a perturbation of the ultraviolet spectrum of fibrinogen arising from the tyrosine and tryptophan residues, but does not change the value of its specific rotation. The phenomenon is reversible, its half-transition temperature is equal to 21°. The light-scattering studies show that a dissociation of fibrinogen occurs at 37° giving a molecular weight of 190 000 for the fibrinogen subunit. By lowering the temperature, there is polymerization. The results of the analytical ultracentrifugation confirm the dissociation of the molecule into subunits, but cannot demonstrate the presence of monomer-dimer equilibrium.     

Influence de la densité de peptides RGD greffés en surface de polyéthylène téréphtalate sur l’attachement des MC3T3

The aim of this study was to evaluate the impact of different densities on MC3T3 cells attachment onto polyethylene terephthalate (PET) film surfaces. Biomimetic modifications were performed by means of a three-step reaction procedure: creation of COOH functions onto PET surface, coupling agent grafting and finally immobilization of peptides. The originality of this work consist, in one hand on quantifying RGD peptides densities grafted onto PET, and on the other hand on studying MC3T3 cells responses after seeding on such biomimetic surfaces. After each functionnalization step, modifications were validated by several physicochemical techniques: X-Ray Photoelectron Spectroscopy permitted to prove the grafting and high-resolution β-imager coupled with use of radiolabelled amino acids served in evaluation of peptides densities. Moreover, this last technique permit us to ensure stability of binding between peptides and polymer. The efficiency of this new route for biomimetic modification of PET surface was demonstrated by measuring the adhesion at 15 hours of osteoblast like cells. Study of cellular comportment was realized by means of focal contact proteins (vinculin, actin) immunostaining.     

Variations de quelques aclivités enzymatiques (peroxydase, catalase, AIA-oxydase) et de la teneur en polyphénols au cours de la germination de I'Orge. Influence de la kinétine

Peroxidase catalase, IAA-oxidase and polyphenol content of growing barley coleoptile. Effect of kinetin. - Kinetin strongly inhibits root and coleoptile growth of germinating barley in the dark. Treated coleoptiles become senescent before the untreated ones. Soluble proteins content, peroxidase, catalase and IAA-oxidase activity were greatly increased in treated coleoptiles while the level of polyphenols was reduced. These biochemical effects joined with the other property of kinetin to diminish α-amylase synthesis in the endosperm are discussed in relation to growth and in connection with the classic view of a cytokinin retarded senescence.     

Effets des variations de la salinité externe sur la teneur en acide N-acétyl-neuraminique (ANAN) de la peau chez l'Anguille

Résumé Le transfert graduel de l'Anguille d'eau douce en eau de mer provoque une augmentation de la teneur en acide N-acétyl-neuraminique (ANAN) de la peau, temporaire chez le mâle argenté, prolongée chez le mâle en cours d'argenture. Les cellules à prolactine de l'adénohypophyse, très actives en eau douce, subissent une lente involution, mais après 30 jours en eau de mer, leur aspect n'indique pas encore un hypofonctionnement très marqué. L'évolution de la mucifieation cutanée et celle de l'aspect des cellules à prolactine ne présentent donc pas de corrélation étroite au cours de l'adaptation à l'eau de mer, surtout après 160 jours.Chez les Anguilles maintenues en eau de mer pendant 20 jours, le retour en eau douce affecte légèrement la teneur en ANAN; elle demeurs très supérieure à celle des témoins restés en eau douce. Les cellules à prolaetine sont stimulées, mais même 10 jours après le transfert, l'image obtenue est encore loin de celle initialement observée en eau douce. Ces changements de salinité modifient les electrolytes plasmatiques. Les corrélations entre ces divers résultats sont envisagées.

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Effects of external salinity changes on N-acetyl-neuraminic acid (ANAN) content of the skin in eelsSimultaneous modifications of hypophyseal prolaotin cells

Summary Progressive transfer of European eels from fresh water to sea water induces an increase in the skin content of N-acetyl-neuraminic acid (ANAN). This increase is of short duration in silver male eels but lasts for at least 160 days in animals studied during the silvering process. In the pituitary gland the cells secreting a prolactin-like hormone are very active in fresh water but slowly regress after transfer to sea water. Even after 30 days the regression is only slight but after 160 days they are markedly hypoactive. The development of skin mucus production and the activity of the prolactin cells are not correlated during adaptation to sea water particularly after five months.The transfer back to fresh water of eels which have been kept in sea water for 20 days, produces slight changes in the skin content of ANAN which, after 2, 5 or 10 days, tends to be lower or similar to that of animals remaining in sea water. However, it remains much higher than in controls maintained in fresh water. This transfer stimulates the prolactin cells but even after 10 days their histological picture is different from that commonly observed in fresh water.Plasma electrolytes are affected by the salinity changes and some correlations among histological and biochemical data are considered and discussed in the light of results obtained by other authors on different teleosts.

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Nous remercions bien vivement Mme P. Martin-Sicard du CNRS qui a effectué les dosages des divers electrolytes plasmatiques et Mlle J. Olivereau du CNRS pour tout le travail histologique réalisé.     

Étude expérimentale des variations de la teneur en eau au cours de la déshydratation et de la réhydratation chez la Fougère:Notochlaena vellea R. Br.

Experimental Study of changes in water content during dehydration and rehydration of the Fern: Notochlaena vellea R. Br.—This study takes place after studies made on otherPolypodiaceen Ferns. We have shown that, in these ferns, the survival duration was longer for the subterranean organs than for aerial ones. The problem was to show that this difference is due to a lower dehydration of the subterranean tissues. As far as we looked at the total water deficiency, we did not find any significant difference between the leaves and the meristematic parts of the subterranean organs: the main difference is the rate of rehydration which is higher in subterranean parts.     

Influence de la température d'élevage sur la fertilité des pontes de Schistocerca gregaria

Thermal conditions, within the range of ambient temperature that permits normal development, colour changes, and the behaviour characterizing sexual maturity of Schistocerca, may influence the fertility of pods estimated as the percentage of viable eggs yielding hoppers. When the insects are kept at 20°C during the night, and from 33 to 42°C during the day, the percentage of hatching is normal and rather constant during the whole parental life. When the diurnal temperature is 30°C, the rate of hatching decreases steadily as the adults grow older. At 28°C, all the pods are sterile from the beginning of the reproductive period.Interbreeding of adults reared at different diurnal temperatures shows that the males are mainly responsible for the sterility of the pods laid at 28°C; under these conditions, copulation occurs but there is no fertilization. Perturbations arising from this low temperature persist since the males do not recover their ability to fertilize females when transferred to a warmer environment.Females too are responsive to thermal conditions, but the functional disturbances provoked by a low temperature are not as serious as in the case of males and they do not last so long. A number of females bred at 28°C can be fertilized. When fertilization does occur, the percentage of hatching depends on the temperature existing at the time of laying and, especially, on the previous thermal conditions. When there is no fertilization, parthenogenetic reproduction can occur with a frequency that increases with a rise in external temperature from 28 to 36°C.     

Influence de la température sur la consommation d'oxygène de micropterna testacea (Gmel.) (Trichoptera Limnophilidae)

Resume Comme suite aux mesures de consommation d'oxygène faites sur les larves de Polycentropus flavo maculatus Pict., Plectrocnemia conspersa (Curt.) et Limnophilus rhombicus (L.) (Colladdeau 1961), il est étudié dans ce travail, l'influence de la température sur la consommation d'oxygène de Micropterna testacea (Gmel.).La consommation d'oxygène de M. testacea croît avec la température. Cet accroissement est faible entre 3 et 7°C. Dés 10°C jusqu'à 20–25°C, cet accroissement est net et régulier. La variabilité des mesures augmente avec la température. Cette courbe métabolisme-température indique une grande sensibilité aux variations de temperature. Ceci oppose la larve de M. testacea aux larves précedem-ment étudiées qui présentaient une bonne adaptation aux températures situées entre 3 et 20–22°C. Cette différence dans l'allure de la courbe métabolisme-température ne serait pas dûe à des différence de température dans les milieux de vie respectifs des larves, puisqu'elles peuvent se trouver ensemble dans le même ruisseau. Elle serait due au fait que les larves de M. testacea, très rhéophiles dans la nature, deviennent très sensibles aux variations de température quand les expériences sont faites en milieu stagnant.

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Summary As a sequence to the study of oxygen consumption in larvae of Polycentropus flavomaculatus Pict., Plectrocnemia conspersa (Curt.) and Limnophilus rhombicus (L.) (Collardeau 1961) the author investigates the influence of temperature on oxygen consumption by the larva of Micropterna testacea (Gmel.).The oxygen consumption of M. testacea increases with temperature, slowly between 3 and 7°C, more rapidly but still regularly from 10°C to 20–25°C. Variability also increases with temperature. Such a Metabolism-Temperature curve indicates great sensitiveness to temperature variations in M. testacea, as a contrast with the precedingly studied larvae, which could be considered as well adapted to temperature ranging from 3 to 20–22°C. Such differences in Metabolism-Temperature curves are unlikely to be due to different temperature occurring in the animals'habitat, as they may all be found together in the same brook. The very rheophilous M. testacea larva becoming sensitive to temperature changes when studied in stagnant water, might ratber account for the difference.

     

Action de la lumiére sur les peroxydases et sur la teneur en composés phénoliques de tissus de feuilles deCichorium intybus L. cultivés in vitro

Three days” illumination of tissues cultured previously in darkness decreases their peroxidase activity and increases their content in phenolic compounds; conversely, when tissues cultured under continuous illumination are placed in darkness for three days, their peroxidase activity increases and their content in phenolic compounds decreases. There is an inverse relationship between the quantity of phenol compound and peroxidase activity. The isoperoxidase pattern is the same in both illuminated and not illuminated tissues.     

Influence de la lumière et de la mycosporine sur la composition stérolique du Nectria galligena au cours de la morphogenese sexuée

The nature and content of free sterols, analyzed by MIKE spectrometry, were investigated in in vitro cultures submitted to different light regimes with or without the addition of exogenous mycosporin. The sterol composition was related to varying degrees of induced sexual morphogenesis, particularly when mycosporin was added to the nutrient medium.     

Variabilité de la teneur en phosphore des ovocytes chez Bombyx mori L.

The weight, total phosphorus content, and phosphorus content as a percentage of fresh weight was determined for oocytes in different positions in the ovarioles in the same female of Bombyx mori L. The weight and total phosphorus content increase up to the fifteenth oocyte, whereas phosphorus expressed as a percentage of fresh weight remains nearly constant although it may vary by about 15 per cent in neighbouring oocytes.     

L'évaluation de l'incapacité dermatologique en santé au travail.

This paper presents a simple method for evaluating the extent of impairment in occupational dermatosis based on the portion (P) of the anatomic area involved (A) and the coefficient of physiologic disturbance (C). A percentage value is assigned to each anatomic area on the basis of its functional importance. The coefficient of physiologic disturbance is the average of four factors (stiffness, dehydration, thickening, and pruritus or pain). The formula (P X A). C gives the final percentage of impairment.