Observations Biologiques et Ultrastructurales sur les Selenidiidae et Leurs Conséquences sur la Systématique des Grégarinomorphes

SYNOPSIS. The taxonomic position of Selenidiidae Brasil in the class of gregarines is discussed in relation to the study of its life cycles, its possible schizogony and the fine structure of its trophozoites. The cycle of gregarines which belong to the genus Selenidium Giard is characterized by trophozoites with pendular or coiling movements, nuclear transformations in gamonts during syzygy just before cyst formation, anisogamy, sporocysts with 4 sporozoites. Schizogony of the Selenidiidae is not yet demonstrated. The “kystes á meérozoites” within the gut epithelium of Sabellaria alveolata, could be one of the stages of schizogony of S. hollandei. This sole example in our study and the absence of schizogony in numerous species, especially in S. pendula, the type species, shows that this criterion is uncertain, actually, in the definition of the order Archigregarinida Grassé. Ultrastructural studies of S. hollandei and S. pendula show that the cortical region in trophozoites of the genus Selenidium is different from that of Eugregarinida. In the Selenidiidae the epicyte is composed of longitudinal folds. Under the wall, consisting of 3 membranes there is a well-defined pellicular fibrillar system. In S. hollandei, the trophozoite has a fibrillar formation, corresponding to a conoid in its anterior region. The trophozoites of S. hollandei and S. pendula contain anterior dense bodies or rhoptries which are very well developed. All these characteristics conform to the ultrastructural organization of the dissemination forms (merozoites, schizozoites, sporozoites): The results allow one to give a new definition of the Order Archigregarinida: Order Archigregarinida (Grassé): Gregarines with ultrastructural organization of the trophozoites similar to that of dissemination forms. Presence of a well defined pellicular fibrillar system. Intestinal parasites of polychaete worms.     

Influence relative de la BAP et de l'IBA sur la néoformation de bourgeons et de racines sur les plantules du Biota orientalis (Cupressacées)

Relative influence of BAP and IBA on the induction of adventitious buds and roots on plantelts of Biota orientalis (Cupressaceae)
Both cytokinin (BAP) and auxin (IBA) have an influence upon the intensity of adventitious bud induction in vitro on hypocotyls of Biota orientalis .
Increase in either the concentration or the length of contact with cytokinin enhances the mean number of neoformed buds per explant, while that of auxin results in an increase of the mean number of reactive explants as well as in the nature of neoformations. Auxin contributes to a restoration of the induction when the length of contact with cytokinin is too short. However, this synergism is only observed when the contract with IBA is simultaneous or follows that with contract with BAP.
Rhizogenesis is also influenced by the auxin-cytokinin balance. An increase in the duration of contact with IBA is always followed by an increased in the mean number of explants forming roots. This organogenesis may be partially or completely inhibited if the duration of contact with cytokinin – before, simultaneously or after that with auxin- exceeds two weeks.     

Caractérisation de la production particulaire par l’oursin Echinometra mathaei sur les récifs Indo-Pacifiques : influence des peuplements coralliens et implications sur la dynamique sédimentaire

The characteristics of the sedimentary grains produced by the sea urchin Echinometra mathaei were described from two reef sites: a fringing Acropora-dominated reef at La Reunion island (Indian Ocean) and a barrier Porites-dominated reef at Moorea island (French Polynesia). The composition of the sediment produced by Echinometra was determined from SEM observations. The size and shape of the particles were measured by using image analysis method. The grain diameters range between a few micrometres and 2 mm, with a large predominance (more than 80 %) of particles smaller than 400 μm. The grain size distribution is dependent on the nature of the grazed substratum. Echinometra individuals collected at La Reunion on branching Acropora colonies produce a higher proportion of particles smaller than 200 μm compared to those collected at Moorea on massive Porites colonies. At Moorea, more grains having a diameter comprised between 200 and 500 μm are produced. The microstructure of coral substrata affects the mean particle diameter, which is 192,17 μm for a Acropora substratum and 244,69 μm for a Porites substratum. Since the sediment derived from Acropora erosion is finer, the proportion of suspended material that is exported from the reef is greater at La Reunion than at Moorea. We estimate that, for similar erosion rates and hydrodynamic conditions, the production of sands by Echinometra mathaei is higher and the retention of this erosional sediment more effective on reefs dominated by massive Porites than on Acropora-dominated reefs. This result is in accordance with the proportions of suspension-moving grains that have been previously measured on Moorea and La Reunion reefs. This study highlighted the effect of coral communities on the production of particles related to the bioerosion and on the sedimentary budget.     

Comparaison de la structure fine des chromatides d'Homo sapiens et de Pan troglodytes

Prometaphasic chromosomes of man and chimpanzee are compared, using R, Q, T and H-bands techniques. — Six pericentric inversions, one telomeric fusion-translocation, 4 intercalar deletions or insertions, 16 deletions or additions of terminal Q-bands, and an important variation of heterochromatin distinguish the 2 species. — The evolutive role of chromosomal rearrangements separating the 2 species is discussed with particular reference to the formation of human chromosome No 2.- The simultaneous analysis of human chromosomal pathology and of the chromosomal structures in primates should contribute to the understanding of accidental modifications of the genome and to the interpretation of their consequences.

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Travail de l'E.R.A. No 47 du C.N.R.S.     

Action de la kinétine sur la croissance et la teneur en chlorophylles des racines

Lens roots form chlorophylls in well-developed chloroplasts when they are cultivated in continuous light. Chlorophyll accumulation was increased when kinetin (10^?4M) was added for a short time (24 h) of treatment. For a long time (72 h), the increase of chlorophyll content was reduced when roots were cultivated in light and with kinetin. When the roots were transferred from light to dark, chlorophyll content was decreased. This reduction was inhibited when roots were treated with kintin. From these present result it was supposed that kinetin acts on the catabolism and the anabolism of chlorophyll. The necessity of kinetin for chloroplast from amyloplast maturation and differentiation was discussed.     

Nouvelles recherches sur l’identité culturelle et stylistique de la grotte Chauvet et sur sa datation par la méthode du C

The discovery of Chauvet cave, at Vallon-Pont-d’Arc (Ardèche), in 1994, was an important event for our knowledge of palaeolithic parietal art as a whole. Its painted and engraved figures, thanks to their number (425 graphic units), and their excellent state of preservation, provide a documentary thesaurus comparable to that of the greatest sites known, and far beyond what had already been found in the group of Rhône valley caves (Ardèche and Gard). But its study – when one places it in its natural regional, cultural and thematic framework – makes it impossible to see it as an isolated entity of astonishing precocity. This needs to be reconsidered, and the affinities that our research has brought to light are clearly incompatible with the very early age which has been attributed to it. And if one extends this examination to the whole of the Franco-Cantabrian domain, the conclusion is inescapable: although Chauvet cave displays some unique characteristics (like every decorated cave), it belongs to an evolved phase of parietal art that is far removed from the motifs of its origins (known from art on blocks and on shelter walls dated by stratigraphy to the Aurignacian, in France and Cantabrian Spain). The majority of its works are therefore to be placed, quite normally, within the framework of the well-defined artistic creations of the Gravettian and Solutrean. Moreover, this phase of the Middle Upper Palaeolithic (26,000–18,000) coincides with a particularly intensive and diversified local human occupation, unknown in earlier periods and far less dense afterwards in the Magdalenian. A detailed critique of the treatment of the samples subjected to AMS radiocarbon dating makes it impossible to retain the very early age (36,000 cal BP) attributed by some authors to the painted and engraved figures of Chauvet cave.     

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.     

Donnè Structurales et Ultrastructurales Nouvelles sur la Conjugaison de Paramecium caudatum.

The morphologic phenomena of the conjugation of Paramecium caudatum are analysed by transverse sectioning of couples at the level of the junction zone. This orientation allows exact determination of the adjacent surfaces (which strongly suggests the absence of a paroral cone) and their relation to the ciliary fields. The modifications of the outer pellicle are studied with the electron microscope. It is shown that cytoplasmic communications occur at the top of the ridges which limit the periciliary depressions. The kinetosomes remain apparently intact but cilia and trichocysts disappear. An active role by the latter organelles is suggested for the union of the two conjugants.     

Caractéristiques Ultrastructurales du Cortex et des Membranelles du CiliéEspejoia mucicola (Oligohymenophora, Hymenostomata, Tetrahymenina)

RESUME. L' étude détaillée du cortex et des organelles buccaux adoraux d' Espejoia montre que ce Cilié possède une organisation ultrastructurale comparable à celle des Tétrahyméniens. Tout en restant conforme au plan général d'organisation de ces derniers, des variations spécifiques décelées tant au niveau du cortex d'une part, que des membranelles, d'autre part, font ressortir des affinités trés marquées pour le genre Glaucoma et autres Ciliés voisins. En conséquence, en nous appuyant en outre sur les données récentes de la morphogenèse, nous confirmons la position d' E. mucicola parmi les Tetrahymenina, dans la famille des Glaucomidae.     

Comparaison paléocognitive des niveaux moustérien et magdalénien de la grotte Tournal (Bize, Aude)

We analyse the functional processing chain of large mammals acquired at the mousterian and magdalenian levels of the Tournal cave (Bize, Aude). Palethnologic results are analysed through a method from experimental psychology of goal oriented activities. The elements are the objects used by prehistoric man and their properties. Objects and properties are linked by binary relationships. These relationships are processed by software, SIMBOL, developed at the IPH, based on an algorithm initially published by the Laboratoire de psychologie expérimentale of Paris-8. SIMBOL returns the cognitive graph of the task representation for the mousterian and the magdalenian layer, allowing a rigorous comparison of the cognitive activities on both periods. The main result is that the logical structure is preserved when passing from one level to the other. This could be interpreted as a due to the noticeable cognitive similarity of the men from the different periods, along with the fact that cognitive complexity seems to be the same on both graphs. Cognitive fluidity improves from mousterian to magdalenian suggesting that cognitive mechanisms such as sense sliding and analogies could be easier at the magdalenian level. Could we interpret this result as a due to a greater creativity at the magdalenian level than at the mousterian one? Further investigations are needed to state this, as well as enhanced data volume, potentially allowed by this entirely new method.     

Role des corpora allata et cardiaca sur l'action cardioaccélératrice de la lumière et de la température chez Locusta migratoria

A rise in temperature as well as the passage from dark to light increases the cardiac beat of adult Locusta migratoria. Continuous exposure to light considerably decreases the sensibility to temperature variations. Neither the corpora allata nor the corpora cardiaca have any influence in this case.