Stabilité de l'espèce et évolution: La théorie de l'équilibre intermittent («Punctuated equilibrium)

Paleontologists' traditional conceptions on evolution do not seem to be in perfect accord with these of biologists. The gradual phyletism is compatible neither with E. Mayr's model of the Founder, nor with the actual stability of most of the paleontological species. The punctuated equilibrium model proposed by N. Eldredge & S.J. Gould offers a solution which integrates both paleontological observations and the data of modern biology.     

Structure cristalline d'une deuxième forme de mélézitose monohydrate. Effet de l'environnement sur la géométrie d'un oligosaccharide

Melezitose [O-α-d-glucopyranosyl-(1→3)-β-d-fructofuranosyl α-d-glucopyranoside] monohydrate crystallizes in two polymorphic forms (I and II). The structure of form II, studied by X-ray crystallography, shows an orthorhombic cell having a 7.135 (4), b 15.362 (8), c 19.134 (8) Å, space group P2₁2₁2₁, and Z 4. The structure, solved by direct methods, was refined to a final value of R 0.045. The molecule of form II seems to be more constrained by its crystalline environment than that of form I. These constraints imply not only little variations in glycosidic bonds, but also a change of conformation for the furanose ring, and a perceptible deformation of the sucrose pyranose ring. This study gives an example of estimation of oligosaccharide molecular-flexibility.     

Influence du piclorame sur l'activité phénylalanine-ammoniac lyase de Nicotiana tabacum induite par la réaction d'hypersensibilité au virus de la mosaïque du tabac

In Nicotiana tabacum var. Xanthi n.c. phenylalanine ammonia lyase (PAL) activity, which increases significantly during the hypersensitivity reaction to tobacco mosaic virus (TMV), is only partially affected when plants are treated with piclorame, which is known to be an inhibitor of PAL in vivo. Using piclorame together with TMV, it has been possible to distinguish between that increase in PAL activity due to the virus and that dependent on the photoperiod.     

Influence de la température sur la cinétique,de croissance et le coefficient de maintenance de Candida lipolytica cultivé sur n-alcane

The effect of growth temperature on the evolution of kinetic parameters and yields was determined for Candida lipolytica cultures with ntetradecane as substrate, in a temperature range of 18°C to 30°C, which is below the critical growth temperature in order to work only in the activation zone of these parameters.In such a culture limited by substrate transfer, growth rate depends on biological rates, related to microorganisms characteristics, and diffusional rates, related to mass transfer. The effect of temperature thus depends on the limiting step. The activation energy, calculated from exponential growth rate determinations is .When the activation energy is calculated from the maximal rate of cell production (determined at the growth curve's inflexion point), it's found to be E _X=71,200 J/mole in the 18°C–24°C range, and E _X=28,000 J/mole in the 24°C–30°C range. The latter one is characteristic of a diffusion-limited process. Above 24°C, growth is controlled by substrate-transfer, as physiological potentialities are preferentially increased with temperature than diffusional ones: 24°C is thus the transition temperature T _t from physiological to diffusional limitation.The apparent yield is almost constant, over the 18°C to 30°C temperature range, although maintenance coefficients are very dependent on temperature. The activation energies related to maintenance coefficients for alkane and oxygen respectively are and .The m _s/m_{O 2} ratio is about 3 (g/g), whereas that, for a strict oxidation reaction of n-tetradecane ought to be 3.47 (g/g). A satisfactory correlation, relating maintenance coefficients to the maximal growth rate of yeast, is given.

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Liste des symboles A constante de saturation de modèle de croissance(1) - B vitesse spécifique considérée - C substrat carboné ou oxygène (g/l) - E energie d'activation (J/mole) - S _m quantité de substrat consommée par maintenance au cours d'une fermentation discontinue (g) - O₂ quantité d'oxygène transférée au milieu de culture (g/l) - R rendement global de la fermentation - R rendement global de la fermentation - constante des gaz parfaits (J/mole K) - S concentration en substrat carboné (g/l) - T température de croissance (°K) - X concentration en biomasse (g/l) - Y rendement limite - m coefficient de maintenance (h^-1) - t duree de fermentation (h) - tømpérature de croissance (^o Celsius) - taux de croissance (h^-1) Indices 1 relatif à la température 1. - 2 relatif à la température 2 - c relatif au substrat carboné ou à l'oxygène - f relatif au temps final - i relatif au point d'inflexion - m maximum - mO₂ relatif au coefficient de maintenance sur l'oxygène - m _s relatif au coefficient de maintenance sur le substrat carboné - o relatif au temps initial - O₂ relatif à l'oxygène - s relatif au substrat carboné - t de transition - T relatif à la température de croissance T - U _m relatif au taux de croissance maximal - X relatif à la productivité maximale en biomasse     

Influence du corps gras sur l'évolution de l'ovaire nymphal de Tenebrio molitor, étude en culture in vitro

In Tenebrio molitor, the fat body contains several factors able to control the evolution of the pupal ovary in vitro. One or several factors soluble in ether inhibit the initiation of oöcyte growth. One or several factors insoluble in ether stimulate the course of this growth, folicle organization, and the appearance of the transitory zone. The inhibitory action of the fat body is greatest towards the middle of the pharate adult stage. The stimulatory action of this organ is maximum at the beginning of pupal life and during the approach of adult ecdysis.     

Scolécodontes,assemblage et appareil de vers annelidespolychetes errantes de l'aptien de la région d'Agadir,Maroc

From the Aptian scolecodonts inventory of the Agadir area one jaw apparatus and one joining of polychetes are reconstructed. One is the elementary species Schistomeringos expectatusSzaniawski & Gazdzicki, 1978, the oldest representative of the multielementary family Dorvilleidae Chamberlin 1919. The other is a representative of either the multielementary families Atraktoprionidae Kielan Jaworowska 1966 emend. Kozur, 1970 or Arabellidae Hartman 1944. This joining is considered as an hypothesis since all the necessary criteria, defined by H. Szaniawski & A. Gazdzicki 1978, are not all present.     

Analyse biostratigraphique et paléontologique de l'Albien marin d'Estremadura (Portugal)

The marine Albain from Estremadura is splited up into four Orbitolinidae zones, adjusted to biostratigraphic scales from mesogean province: zone with Orbitolina (Mesorbitolina) minuta (lower to middle Albian); zone with Neorbitolinopsis conulus (base of upper Albian); zone with Orbitolina (Orbitolina) concava (top of upper Albian) and zone with Orbitolina (Orbitolina) duranddelgai (Vraconian). The vertical extension of the main fossils is replaced in the framework of these zones. The most interesting species for biostratigraphy, paleoecology or taxinomy are summarily described.     

L'action exercée par l'appareil endocrine sur les phases tardives de l'ovogenèse chez Locusta migratoria

Most studies dealing with the endocrine control of oogenesis are focused on vitellogenesis, but the later events of oogenesis: vitelline membrane formation and choriogenesis have received less atention. In Locusta migratoria, the corpora allata evidently control vitellogenesis, but seem to have no bearing upon the formation of the vitelline membrane or the chorion. If the insects are deprived of their CA at the time when the oocyte length is around 3.5 to 4 mm, (normal length at egg laying: 6.5 mm) vitelline membrane formation and the chorion production are unaffected. In the same species, the electrocoagulation of the pars intercerebralis or excision of corpora cardiaca disturb oogenesis; vitelline membrane material is synthesized and secreted, but the primary granules fail to join each other and to transform into vitelline membrane and the production of chorionic material is disturbed.The rER of the follicle cell seems quite active but the substance elaborated accumulates in the Golgi saccules, and therefore the cytoplasm contains only very few secretory granules. The implantation of supernumerary pars intercerebralis and corpora cardiaca into immature females induces precocious deposition of the vitelline membrane which is complete in 5.0 mm oocytes (instead of 5.6 to 6.0 mm) and chorion formation is completed in 5.5 mm oocytes (instead of 6.0 to 6.3 mm). Ecdysone is secreted in the ovaries at the end of oogenesis. We tested the result of injecting ecdysone to immature females. It results in hastening oocyte growth during 24 hr, but this accelerated growth is followed by degeneration.     

Modalités d'installation et d'évolutiondes Harpocératinés (ammonitina A) au Domérien inférieur dans le sud-Ouest de l'Europe (France,Portugal)

In Mesogea, the Harpoceratinae were known asearly as the end of the Lower Carixian. They later reached the sub-boreal province through the Alps or the South of the Iberic Peninsula. The analysis of the populations met in four crosssections of the Lower Domerian (Causses, Mâconnais, Franche-Comté, Portugal) showed the settling down of the Protogrammoceras isseli group that set up and evoluated in a similar way in the different areas in spite of a certain originality.On the one hand, it gave the cladogenetic groupP. monestieri-nitescens by diminution of the ribing density, strengthening of the ribs and simplification of the suture.On the other hand, a slower evolution give, near the end of the Stokesi zone, P. normanianum in the Paris Basin and in Burgundy, and P. lusitanicum in Portugal. At the same time, a new invader, P. celebratum, arrived in the Causses (and in Portugal).     

Action de l'antimycine a sur l'activité succinoxydase des mitochondries du tubercule de Pomme de Terre,et comportement des cytochromes de type b

A kinetic study of the effect of antimycin A on succinate oxidase from plant mitochondria produced sigmoidal curves for the reduction of cytochromes b₅₆₀ and b₅₈₅ and for the inhibition of succinate oxidase. In the stationary state the interaction of the various components of the respiratory chain (flavins, ubiquinone, cytochromes…) occurs in a sequential mode which allows the application of simple equations utilizing rate constants and cytochrome concentrations. In these equations, it is assumed that there exists an excess of ubiquinone relative to other components of the respiratory chain as suggested by Kröger & Klingenberg (1970) and that the reoxidation of b cytochromes is fast. The inhibition by antimycin A, characterized by non-linear inhibition curves for succin-oxidase and inhibitor fixation in complex III on a component other than cytochrome c₁, is interpreted in terms of this model. This hypothesis presupposes the existence of an F factor between cytochrome b₅₆₀ and cytochrome c₁ as suggested by other authors. Utilizing these equations, theoretical curves for the inhibition of the reduction of cytochrome b₅₆₀ have been constructed and the results agree with the experimental data. The kinetic behavior of cytochrome b₅₆₆ during the induction of anaerobiosis suggests that it is not directly involved in the electron transfer chain but rather is either in thermodynamic equilibrium with cytochrome b₅₆₀ or in a shunt between cytochrome b₅₆₀ and factor F. From the experimental data, an equation is derived for the inhibition of the reduction of cytochrome b₅₆₆ by antimycin A. The actual effects of ATP and mClCCP on succinoxidase agree well with those predicted by the model.     

Nouvelles données micropaléontologiques(Foraminifères planctoniques et petits Foraminifères benthiques) sur le stratotype de l'Aquitanien

The authors study the microfauna of small benthonic and planktonic Foraminifera from the Aquitanian stratotype and of a few exposures in the stratotype vicinity.Benthonic microfauna is rich: more than 150species have been collected; among them Miliolidae mainly belonging to the genera Quinqueloculina and Miliola.Planktonic Foraminifera are much less abundant:only 20 species. They authorize to place the stratotype at the boundary of N4–N5 Blow's zones.The figurations of many species are made withthe scanning electronic microscope.     

Le rôle du système nerveux central sur les mécanismes de l'oviposition chez Carausius morosus et Clitumnus extradentatus

Cephalic nervous connexions were found necessary for oviposition and normal egg maturation in the two species studied. Neurosecretory cells of A type from the brain, suboesophageal, thoracic, and four abdominal ganglia seem to elaborate a stimulating substance for egg laying. This neurosecretion type is not present in corpora cardiaca, corpora allata, the four last abdominal ganglia, or perisympathetic organs which have no clear-cut effect on oviposition. The circadian rhythm of egg laying appears to be entirely controlled by the liberation of this neurosecretion and by an inhibitory factor localized in the head.In Carausius, egg deposition by the valvulae of the ovipositor is regulated by these two factors whereas egg transit through the common oviduct is a distinct preliminary step under nervous control. This nervous effect from the posterior region does not exist in Clitumnus.     

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.     

Cycles embryonnaires et sécrétion de la cuticule chez l'embryon de blatte, Blabera craniifer

Cuticle deposition has been studied with the electron microscope in cockroach embryos (Blabera craniifer) during normal incubation in situ and in culture in vitro, in the absence or presence of inokosterone (a phytoecdysone).Two cuticles are deposited successively during embryonic life, respectively between stages 11 and 17, and stage 21 and 24 hr after hatching. The occurrence of two embryonic cycles is thus demonstrated, the first ending at stage 17 without exuviation since there is no old cuticle to be shed, the second one at hatching.In embryos explanted at stage 17 and cultured in vitro, the formation of cuticle 2 occurred at the same rate as in situ. The addition of inokosterone (50 μg/ml) to the medium resulted in the early onset of cuticle deposition (in 3 days as compared with 15 days in situ) in legs previously cut at the base of the tarsus. Cuticle 2 was completed within 9 days after explantation (as compared with about 20 days elapsing in the normal embryo between stage 17 and the completion of cuticle 2). Unsectioned appendages were insensitive to the hormone.Regeneration of sectioned legs, which occurred normally n vitro in non-treated embryos, was completely inhibited in the presence of inokosterone, presumably because the hormone caused early immobilization of cells through accelerated cuticle formation.Results suggest that embryonic cycles are controlled by the same hormonal mechanism as larval cycles.     

Activité cytokinine de dérivés acylés,alkylés,acyl-alkylés de l'adénine et d'isost`eres azotés de la γ,γ-diméthylallyladénine

The cytokinin activities of various 6-acylaminopurines, 6-alkylaminopurines, 6-acylamino-9-benzyl-purines as well as a series of isosteric-nitrogen derivatives of N⁶-(γ, γ-dimethylallyl)adenine (I⁶Ade) have been tested using the tobacco pith and the pea bud bioassays. The interactions between active, slightly active and inactive compounds have been studied with the last assay. Acylation decreases the biological activity; e.g., N⁶-benzoyl and N⁶-furoyladenines are less active than Na⁶-benzyladenine and kinetin. Substitution at the 9-position reduces (tobacco-pith assay) or suppresses (pea-bud assay) the phytohormonal activity of otherwise active 6-acylaminopurines. In isosteric derivatives, maximum activity occurs when the side chain has the same length as in 1⁶Ade. After the analysis of interactions between more or less active compounds, it is suggested that the differences in cytokinin activity could be related to unequal affinities for a hypothetical receptor site.     

A propos des fossiles du Pliocène d'Aguilas(Sud d'Almeria,Espagne) découverte de Cirripèdes operculés (Crustacés) et discussion sur l'étho-écologie des formes épizoaires

A benthic taphocoenose from the Pliocene I of Aguilas (provinces of Murcia-Almeria, Southern Spain) conseals four Cirripedia (family of BalanidaeLeach): Balanus (Balanus) perforatus angustusGmelin, B. (B.) amphitriteDarwin, B. (Megabalanus) tintinnabulum tintinnabulumLinné and Creusia (Withersia) phryxaPajaud.The study of the last one is especially interestingfrom an ecological point of view. Indeed, all species, well-known in the Creusia-Pyrgoma group are more or less dependent on Anthozoa since Miocene, the cuplike basis of their shell buried on corallites. But not corallites were gathered in the deposits of Aguilas and the morphology of Creusia phryxa leads us to believe a fixation of the shell on a flaccid substratum. From which we may suppose that the host of this Cirriped was perhaps an Actiniaria.     

Influence du chlorure de zinc sur l'inversion des sexes et sur le développement et la différenciation d'éléments germinaux supplémentaires chezEisenia foetida Sav. (Oligochète,Lumbricidae)

Résumé L'action du chlorure de zinc, connue par les modifications morphogénétiques qu'elle entraîne chez des embryons de Vertébrés et d'Invertébrés, a été étudiée sur la différenciation sexuelle d'Eisenia foetida, hermaphrodite à gonades séparées.Il est apparu que le chlorure de zinc entraîne des inversions dans les testicules et les ovaires. Il favorise en outre le développement et le maintien d'une lignée germinale, en dehors des segments gonadiques normaux, tant dans le territoire présomptif mâle que dans le territoire présomptif femelle. La différenciation de cette lignée germinale supplémentaire a été étudiée. Les conclusions de ces recherches soulignent les difficultés d'application, au cas des Lombriciens, de la théorie de l'autodifférenciation de la lignée femelle.

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Influence of zinc chloride on the inversion of sexes and the development and differentiation of additional germ elements inEisenia foetida Sav. (Oligochaeta, Lumbricidae)

Summary We have studied the effect of zinc chloride, known for the morphogenetic changes it causes in embryos of Vertebrates and Invertebrates, on the sexual differentiation ofEisenia foetida, a hermaphrodite with separate gonads.There was evidence that zinc chloride causes inversions in the testes and ovaries. It also helps the development and survival of a germ line outside the normal gonadal segments, in the presumptive male territory as well as in the presumptive female one. We have studied the differentiation of this additional germ line.The conclusions drawn from this study emphasize the difficulties of applying the theory of self-differentiation of the female line to the case of earthworms.

     

Etude cytochimique et ultrastructurale de l'évolution ovocytaire de Nereis pelagica L. (Annélide Polychète)

Résumé Les ovocytes de N. pelagica d'un diamètre inférieur à 100 ne renferment dans leur cytoplasme que des inclusions lipidiques et vitellines. Les lobules vitellins s'accroissent par l'adjonction de vésicules golgiennes.L'approche de la maturité sexuelle est caractérisée par l'apparition de mucopolysaccharides acides. Corrélativement à l'élaboration de ce matériel, l'appareil de Golgi présente, à ce stade, de profondes modifications morphologiques: dilatation des saccules distaux et libération dans le cytoplasme de vacuoles golgiennes. Les processus de vitellogenèse cependant ne sont pas entièrement stoppés.Dans les ovocytes matures, les lobules mucopolysaccharidiques forment une gangue corticale. Les dictyosomes sont refoulés vers l'intérieur du cytoplasme et présentent des figures d'involution.La présence de lamelles annelées intra-nucléaires a été observée de façon constante dans tous les ovocytes matures examinés.

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Cytochemical and ultrastructural study of oocyte development in Nereis pelagica L.I. Normal ovogenesis

Summary The oocytes of N. pelagica, the diameter of which is smaller than 100 , contains only lipid and yolk inclusions in their cytoplasm. The yolk bodies grow by confluence of Golgi vesicles.The advent of the sexual maturity is marked by the appearance of acid mucopolysaccharides. Concomitantly with the production of this material, the Golgi apparatus shows typical morphological modifications: dilatation of the distal saccules and release of Golgi vacuoles into the cytoplasm. However vitellogenesis is not completely terminated at this point.In the mature oocytes the mucopolysaccharid material forms a cortical layer. The dictyosomes are pushed toward the center of the cytoplasm and show signs of degeneration.The presence of intranuclear annulate lamellae is a constant feature in all mature oocytes examined.