Action de l'ecdystérone sur l'apolysis et l'ecdysis de divers crustacés isopodes

Ecdysterone acts differently according to the period of the moulting cycle when it is applied. In period C it induces apolysis, while at the beginning of apolysis it delays ecdysis. Experiments show that the exoskeleton cannot be rejected in the presence of ecdysterone. The possibility of stopping exuviation or ecdysis with ecdysterone seems to prove that this phenomenon is controlled by a particular factor called the factor of exuviation or the ecdysis factor. Ecdysterone would control only the release of this specific factor but would not prevent its action.     

13C NMR des alcaloïdes des Strychnos: Les dérivés de l'harmane et de l'usambarensine

¹³C NMR spectra of some tertiary and quaternary indole alkaloids are recorded and the signals assigned. Graphic interpretation of off-resonance spectra and substituent shielding effects together with the effect of N_b-methylation are utilized in the spectral interpretation.     

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.     

Utilisation de lois de la mécanique pour l'Estimationde la vitesse de locomotion des Vertébrés tétrapodes du passé

Two computation methods are explained; theirobject is the estimation of the velocity of animals which are known by their footprints, and in the case of the first method, by their skeletons as well.The first method is based on the compound pendulum theory, because during the slow walking gait, the motion of the leg is similar to the oscillation of a pendulum, for the computation of the velocity (v), are considered: moment of inertia (I), radius of gyration (P) and period (T), time in seconds to cover one stride (E) in the case the maximum angle of divarication (δ) of the leg with the vertical is ≤20°. A comparison with the formula of Alexander (1976) is discussed.The second method concerns saltator animals. It is based on the fondamental laws of dynamics. With the length of the jump (E) it is possible to estimate the velocity of the trackmaker (v) and the height of the jump (K). For the vertebrates the angle of the trajectory with the horizontal plan (α) is between 20 and 45°. Thus, the result of this method is an interval of estimation in which the velocity is included.These methods do not give precise results. But these approximations supply valid informations on the velocity of extinct or living animals and can lead to the estimation of their maximum speed if the parameters E, T, vary. The problem of the errors is also discussed. It is shown that the errors in estimating the parameters have a no significant influence on the results.     

Etude au microscope electronique de l'ultrastructure du centriole chez les vertébrés

Zusammenfassung Die Ultrastruktur des Zentralkörpers wurde beiTriton, Pleurodeles, Maus, Ratte undHühnchen elektronenmikroskopisch untersucht. In allen Fällen stellt sich dieser Körper als Hohlzylinder mit einem Durchmesser von etwa 150 m und einer Länge von 300–500 m dar. Seine Wandung, die stark osmiophil ist, besteht aus etwa 9 Röhrchen, die untereinander und zur Achse des Zylinders parallel angeordnet sind. Der Zentralkörper liegt entweder am Spindelpol von Mitosen oder in der Nähe der Nuclearmembran und des Golgiapparates im Cytoplasma von ruhenden Zellen.Die an normalen Gewebe beobachtete Ultrastruktur des Zentralkörpers wurde ebenso in verschiedenen Krebsgeweben und in Zellen, die der Wirkung von Colchicin oder Natrium-Kakodylat ausgesetzt waren, nachgewiesen.Die Spindelfasern erscheinen als kleine Kanäle mit einem Durchmesser von 20 m; sie sind bei einer großen Mehrzahl von Mitosen, die der Wirkung von Mitosegiften ausgesetzt waren, nicht nachweisbar.Die Ultrastruktur des Zentralkörpers entspricht derjenigen des Basalkörperchens des Flimmerepithels und des proximalen Zentralkörpers der Spermatozoen.Der Zentralkörper erscheint als ein hochdifferenziertes Organ, dessen Ultrastruktur, je nach den verschiedenen Anforderungen der Zellentwicklung, die Synthese von Faserproteinen möglich macht.     

Les premiers vertébrés et les premières étapes de l’évolution du crâne

The earliest vertebrates and the first steps of the evolution of the skull. Vertebrates are one of the few metazoan taxa, which display a well-corroborated phylogenetic pattern, a good and anatomically informative fossil record, and a relatively slow ontogenetic development. They are thus a favourite taxon for illustrating evolution as a historical process, although the stem of the vertebrate tree remains poorly documented by fossils, except for some Early Cambrian forms. Therefore, the characterization of the vertebrates now rests essentially on a small number of developmental characters, mostly involved in the rise of the skull, and whose precursors may occur in other chordates. The tree of the crown-group vertebrates also shows some major morphological gaps due to early extinctions, but a number of Palaeozoic stem gnathostome taxa helps in documenting the agnathan-gnathostome evolutionary transition. However, stem cyclostomes remain elusive.     

Les vertébrés du Berriasiende Canjuers (Var,France) et leur environnement

The vertebrate fossil locality of Canjuers correspondsto a protected marine environment near an emersive zone, on the shelf of Middle Verdon, in communication with the open sea (toward the North) through channels. The fishes (carnivorous pelagic and planctonivorous pelagic) are the most abundant vertebrates. They were already dead when they reached the depositional area, together with the floated shells of ammonites. The necton, dependent on the bottom for its food and the fixed benthos are nearly absent. The free and sessile benthos, poor in species, shows adaptations to a muddy bottom and rare forms adapted to a hardened bottom. The microfauna is rare. The infauna (essentially horizontal) is present inside the channels. The water temperature, the very low hydrodynamism and the lack of infauna imply difficult conditions on the bottom (micrite beds and laminites in the lower part of the deposit). Tridactyle tracks of vertebrates confirm, on the other hand, the feeble depth of the water. The near supratidal zone was more or less colonised by vegetation and was occupied by a very differentiated reptilian fauna (flying forms, continental running and burrowing forms, swimming forms) corresponding to a continental environment. The biotic and abiotic factors show the occurence of four distinct environments: protected low depth marine, channels, supratidalintertidal and pure marine. The taphonomy corroborates that the deposit was a thanatocoenosis for the marine organisms, except when water movement permitted life.     

Purification de l'alcool deshydrogénase de tomate par chromatographie d'affinité

Tomato alcohol dehydrogenase has been purified 99-fold by affinity chromatography on Blue Sepharose CL-6B with 37% yield. The enzyme so obtained is homogenous in polyacrylamide gel electrophoresis. By adding 20% glycerol to the extraction and purification buffers, an enzyme is obtained which is stable for several months at 4°. The molecular weight values determined by gel filtration (Sephadex G 200) and polyacrylamide gradient gel electrophoresis on one hand and by polyacrylamide gel electrophoresis in sodium dodecyl sulfate on the other, show that the enzyme exists in dimeric form.     

Nouvelles recherches sur la vitesse des vertébrés,auteurs de traces fossiles

This paper follows up on one published in Geobios1984, on the estimation of the velocity of trackmakers represented by fossil trackways.A simplification of the previously given formulaewill make it easier to calculate estimations of the lengths of «apparent limb, period and velocity of a walking animal. Observations show that the «walking angle decreases with the size of animals (in the case of a slow walk), the diminution being due to the exponential rising of the moment of inertia, a mathematical relation is proposed that links the «walking angle to the length of the radius of gyration i.e. the length of the «apparent limb. This relationship agrees with some datas from ichnology and with observations of living animals. With this equation and others presented here a table has been worked out which gives the estimates of «apparent limb, «walking angle, in terms of stride, estimates comprised in an interval of likelihood given by the coherent different values of the «walking angle. Velocity come from the pendular period. Interpolations from this table permit its utilization so for the values of the stride length distinct that presented.     

Relation métabolique entre l'arginine et l'acide γ-aminobutyrique dans le fruit de Castanea sativa: étude préliminaire de l'arginase

Analysis of the free amino acid pool in the chestnut fruit (Castanea sativa) shows that it is high in γ-aminobutyric acid. A metabolic connection between arginine and γ-aminobutyric acid is evident. Three enzymatic activities are involved: L-arginine ureohydrolase, L-ornithine 2-oxo-acid aminotransferase and L-glutamate carboxylyase.     

Paléohistologie et paléobiochimie des vertébrés dans les Annales de Paléontologie

With the exception of one paper published in 1929, works in vertebrate paleohistology start to be published in the journal in 1968 and are published ever since. Similarly, the first paper in vertebrate paleobiochemistry is published in the journal in 1987 and the field is regularly covered ever since. The relatively late publication of paleohistological researches in the journal is all the more surprizing because there are evidences now that several laboratories at the Paris Museum heavily invested in paleohistology already in the 1870–1890th and gathered extensive collections of thin sections, but very few publications followed. The scientific and contextual causes of the late development of the paleohistological publications in the journal are briefly analyzed. It appears that its history is a fairly faithful reflection of several changing scientific and historical constraints which framed not only french paleontology (and notably the “Paris school”) but french biology as well during the XXth century.     

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.     

Recherches expérimentales sur l'action des rickettsies des invertébrés sur les vertébrés: Étude de l'infection nasale et buccale chez la souris parRickettsiella grylli

Résumé Une rickettsie entomopathogène:Rickettsiella grylli proche des chlamydies par son cycle de multiplication est introduite chez la souris par voie nasale et par voie buccale. La rickettsiose expérimentale produite est étudiée sous les aspects clinique, anatomopathologique, sérologique et histologique. Les rickettsies sont recherchées dans les tissus par immunofluorescence et microscopie électronique. Chez les souris infestées par voie nasale, les rickettsies restent localisées dans les poumons. Lors des contaminations fortes, ces derniers subissent une hépatisation et une bronchopneumopathie se développe; cette pneumopathie se maintient pendant eviron 2 mois puis évolue, dans de nombreux cas en une bronchopneumopathie chronique durant plus d'un an. Les souris élaborent des anticorps agglutinants spécifiques dont le taux est proportionnel à l'atteinte pulmonaire. L'infestation par voie buccale ne détermine aucun effect pathologique à court ou long terme.

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Summary Rickettsiella grylli Vago & Martoja is a rickettsial entomopathogen close to the chlamydia by its multiplication cycle. This organism has been inoculated in mice by intranasal and oral routes. The experimental rickettsiosis has been studied by the clinical syndromes, anatomopathology, serology, histology, immunofluorescence and electronic microscopy. By inhalationR. grylli is localized in lung tissues. In heavy contaminations the lungs present hepatisation and a bronchopneumopathy that last 2 months and evolves to a chronic bronchopneumopathy in 50 % of the tested mice. Agglutinin type antibodies are produced and their concentration are proportional to the severity of the lung infection. No short term or long term pathological effects are detected by oral administration.

     

Découverte de vertébrés aquatiques présumés paléocènes dans les Andes septentrionales de Bolivie (Rio Suches,synclinorium de Putina)

The teleost fish Brychaetus and a dyrosaurid crocodilewere recognized among the aquatic vertebrates recently discovered in the northern area of the Titicaca lake (Bolivia). These fossils allow the presumption of a Paleocene age for the vertebrate bearing formation. The structural interpretation of this chronological data is discussed.     

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.     

Les Rhynchonelles du Bathonien du domaineprovencal: Liaison entre l'installation des peuplements et les modalités de la transgression bathonienne dans les Alpes-Maritimes

In the Maritime Alps, the Middle and Upper Bathoniancorresponds to a transgressive episode on the Provençal platform. The advancement of the marine invasion is very noticeable between Grasse and Antibes. The sediment shows the existence of a shallow marine environment in which benthic organisms were predominant.The deposits are at first varied: marly layers withbivalves (burrowers for the most part) and calcareous layers with monospecific populations of brachiopods (Burmirhynchia mediterranea nov. sp. in a calm environment, and B. turgidaBuckman in a more turbulent environment).The deposits then become uniform and show theexistence of very shallows environments: B. decorata kiliani nov. subsp. is the only representative of macrofauna in the micritic limestones that can be attributed to the Upper Bathonian.The Rhynchonellids, as on the other Bathonian carbonateplatforms of Western Europe, seem to be the only organisms likely to stay alive and proliferate in the specific environments in which entirely carbonate sediments are deposited in shallow water. Due to their relationships to those existing in other platforms, the species described in this article permit the clarification of biostratigraphic correlations.