Sur quelques echinodermes(Cystoides et Crinoides) de l'Ashgill d'Aragon (Espagne)

The material collected in the outcrops of Fombuenaand Luesma allows to specify the distinctive characters of the genera Corylocrinus and Caryocrinites, to describe two new species and to complete the morphology of Heliocrinites rouvillei and Proteocystites hispanica. The Crinoid association of these localities shows a very close composition with that of Coat-Carrec (Finistère). The new observations establish definitively the structure of the dorsal cup and the oral face of Mespilocystites. The occurence of the genera Stichocystis, Eucystis and Mespilocystites is recorded for the first time in Aragon. Cystoids and Crinoids confirm the existence of Ashgillian in the western part of the Armorican Massive.     

Phenylpolyenes d'Aspergillus niger: structure et proprietes de l'asperrubrol

When grown on a synthetic medium containing Zn²⁺ and Cd²⁺ in toxic concentrations and a high concentration of Mg²⁺, the mycelium of Aspergillus niger ATCC 9029 is pigmented yellow. Four pigments have been chromatographically separated. Two are still unknown; the others are asperenone and asperrubrol. Asperrubrol is the methyl ester of a dimethyl 13-phenyl-3-ol-2,4,6,8,10,12-tridecahexaenoic acid. One of the methyl groups is on C₂ and the other is probably at C₈. Asperrubrol has been obtained as the enol of the all trans molecule; ketoe nolisation can be obtained by action of heat or alkalis. When grown on the same medium, 13 of 17 strains of A. niger produced asperrubrol and asperenone.     

Fluctuations du taux d'AMP cyclique et des activites adenylate cyclase et AMP cyclique-phosphodiesterase dans les cultures synchrones d'un procaryote, Nocardia restricta

Cultures of Nocardia restricta, a prokaryote from the group of Actinomycetes, can be synchronised by diluting, in a fresh growth medium, cells already in stationary phase. The synchronisation of the cultures is monitored by examining the synchrony of DNA replication.In these synchronised cultures, the intracellular cyclic AMP level exhibits rythmic oscillations with a period equal to the generation time of the culture. There is only one peak per generation. The average ratio of maximum to minimum concentrations is at least 3.Cyclic AMP accumulates also in the medium with a step pattern. It appears in the medium during maximum production of cyclic AMP in the cell.The specific activity of adenylate cyclase (EC 4.6.1.1) measured in the 30 000 × g pellet of cell-free extracts also oscillates and correlates well with fluctuations in the cyclic AMP level. At the end of exponential growth, cyclic-AMP phosphodiesterase (EC 3.1.4.17) is detectable in the cells. The specific activity of this enzyme measured in the 30 000 × g supernatant of cell-free extracts shows also an oscillating pattern.To our knowledge it is the first time that such oscillations in the metabolism of cyclic AMP are described among prokaryotes. It is now possible to look at a link between this phenomenon and the cell cycle of the organism.     

First radiation of Cretaceous planktonic foraminifera with radially elongate chambers at Angles (Southeastern France) and biostratigraphic implications

The study of planktonic foraminifera from the Lower Cretaceous succession at Angles (Southeastern France) directly correlated with ammonites, confirms that the origin of morphotypes with radially elongated chambers occur earlier than previously recorded. In particular, the species Hedbergella semielongata and Hedbergella roblesae bearing subclavate to clavate chambers first appear in the upper Hauterivian, just predating the onset of the oceanic anoxic Faraoni event. Based on these observations, a new zonation is proposed.     

Megapedetes aegaeus N. SP. (Pedetidae) et a propos d'autres “rongeurs africains” dans le Miocene d'Anatolie

Three species of so-called “African rodents” (Megapedetes aegaeus n. sp., Phiomyidae indet. and Dakkamys sp.) have been recently discovered in Western Anatolia in the Middle Miocene localities of Bayraktepe, Chios and Yeni Eskihisar. The first species alone is described and discussed in this paper. The occurence of such rodents in Anatolia leeds to an evaluation of the special paleogeographic position of Africa to Asia at this time.     

Biostratigraphie,paléoécologie et zones d’acmé des foraminifères planctoniques au passage Crétacé-Paléogène dans la Téthys (Tunisie et Espagne) et l’Atlantique (France)

Biostratigraphical high-resolution analyses and quantitative data confirm that deposition is continuous across the K-Pg transition in several sections in Tunisia (El Kef, stratotype section) and Spain (Agost and Caravaca sections) located in the Tethyan realm and the Bidart sections in the Atlantic realm, without any relevant hiatus. The Upper Maastrichtian assemblages of planktic foraminifera from these sections are largely dominated by small biserial heterohelicids. They are associated to common species having planispiral test (i.e. globigerinelloids), trochospiral test (i.e. hedbergellids, rugoglobigerinids globotruncanids), to rare triserial heterohelicids (i.e. guembelitriids) and trochospiral species showing tubulospines (i.e. schackoinids). Stratigraphical ranges of these diverse taxa through the late Maastrichtian in the Tethyan and Atlantic realms show very few changes in the planktonic foraminiferal assemblages and most of the species are present in the Abathomphalus mayaroensis biozone. By our high-resolution sampling and the intensive research for the A. mayaroensis index species in the uppermost Maastrichtian samples, we confirm that this species is omnipresent up to the top of the Maastrichtian. Therefore, A. mayaroensis is present in almost all samples which are late Maastrichtian in age, but this species became very scarce in the uppermost Maastrichtian samples. This scarceness could be due to a climate cooling. A sharp decrease in relative abundance of the deep dwellers species, like as Abathomphalus intermedius and A. mayaroensis as well as in other keeled globotruncanids is observed at the studied sections from the Tethyan realm (indicative of low latitude) across the latest Maastrichtian. At the K/Pg boundary, all the globotruncanids disappeared. They are considered specialists living in tropical-subtropical deep seawater habitat. At this boundary, large and ornate heterohelicids also disappeared. Therefore, all the studied sections show that about 90 % of the Maastrichtian species became extinct according to a catastrophic mass extinction pattern. Only about 10 % crossed the K/Pg boundary and survived during the earliest Danian. The minor difference in the number of disappeared taxa is related to their latitude location or environment paleodepth. The changes in the species relative abundance, observed in the successive planktic foraminiferal assemblages, make it possible to recognize the Acme-stage 0 typical of the upper Maastrichtian interval. It is characterized by the highest species richness of Globotruncanids and heterohelicids specialists of tropical to subtropical marine conditions, the Acme-stage 1 typical of the Guembelitria cretacea Zone, and in particular of the Hedbergella holmdelensis Subzone dominated by “opportunists” species belonging to Guembelitria, the Acme-stage 2 which corresponds to the Pv. eugubina Zone dominated mainly by specimens belonging to Palaeoglobigerina and Parvularugoglobigerina and the Acme-stage 3 which characterizes mainly the Ps. pseudobulloides Zone dominated by biserial species belonging to Chiloguembelina and Woodringina.     

Cinetique d'action de l'acide 2-chloro ethylphosphonique sur les polyribosomes du latex d'Hevea brasiliensis

Effects of 2-chloroethylphosphonic acid on the latex of Hevea brasiliensis were studied during 7 days after its application on the tapping panel of the tree. Ribosome polymerisation shows a dramatic rise within 12 hr after treatment. This shift is overcome at first without rRNA synthesis. Increase of latex production and latex pH exhibit similar features and start 24 hr after application of the, stimulant. After 4 days, rRNA concentration and the stability of the lutoïds (microvacuoles with lysosomal characteristics) change significantly.     

Mise en évidence d'une corrélation entre la fréquence de variations somatiques sur feuilles et l'état physiologique d'un mutant chlorophyllien monogénique chez Nicotina tabacum var. samsun

After treatment with ethyl methanesulphonate (EMS), a chlorophyll mutant of Nicotiana tabacum var. Samsun has been obtained in M₁. Spontaneous somatic variations are observed as isolated areas in the pallisade cells, both on heterozygous and on homozygous plants for the semi-dominant tl gene. These variations appear either as single (green or clear), or as twin (green and clear) areas. This paper reports on the distribution of green somatic variations only, on the basis of the foliar level. The observations have been carried out on a clone homozygous for the tl gene.A highly significant correlation is evidenced between the frequency of somatic variations per leaf and/or per million of cells on the one hand and the physiological stage of the plant on the other. A consistent decrease in the number of variation, after a certain foliar level, is correlated to the transition of the shoot apex from the vegetative to the flowering stage. Modifications of the intracellular conditions caused by this transition could prevent the event responsible for the occurrence of somatic variations. It is also suggested that this event can only take place at a given stage of cell differentiation.     

Les Flavonols d'Asclepias Syriaca

Eight flavonoids are present in the leaves of Asclepias syriaca. Three have been identified as quercetin, kaempferol, isorhamnetin; a structure of a fourth, 3,5,3′,4′-tetrahydroxy-7,8-(2″,2″-dimethyl-4″-methyl-5″,6″) pyranoflavone(I), has been established by study of its spectral properties (UV, IR, MS, NMR) and those of its acetate.     

L'alcool deshydrogénase de tomate (Lycopersicon esculentum): Étude cinétique et mécanisme d'action

In order to investigate the enzymatic mechanism of tomato alcohol dehydrogenase, kinetic studies were carried out at pH 5.8 and 9.4 for the forward and reverse reactions, respectively. Primary double reciprocal plots for several fixed concentrations of the associated substrate in all cases intersect, suggesting a sequential mechanism. Exploitation of secondary plots (slope-intercept values on the primary plots versus the reciprocals of the non-varied substrates) gives the following values: K_ms 500 μM for MeCHO, 30 μM for NADH, 2700 μM for EtOH, 12 μM for NAD⁺; K_is 40 μM for MeCHO, 3 μM for NADH, 10⁴ μM for EtOH and 45 μM for NAD⁺. The results obtained in product inhibition studies agree with an ordered bi-bi mechanism for both forward and reverse reactions. Application of Cleland's rules shows that the coenzyme was the first substrate to complex with the enzyme in both cases.     

Grandifloroside et methylgrandifloroside,glucosides iridoides nouveaux d'Anthocleista grandiflora

From the bark of Anthocleista grandiflora, two new iridoïd glucosides were isolated, and their structures established.     

Origine et caracteres de la sécrétion d'aglycones flavonoliques par les bourgeons d'Aesculus hippocastanum

Flavonol aglycones are present in the oil excreted by buds of Aesculus hippocastanuml. and are probably synthesized in glandular hairs situated on the inner side of bud scales. Flavonols are most abundant in the hairs, being much less concentrated in all other scale tissues. Flavonol accumulation in the buds reaches a maximum both in the Spring and the Autumn and this is related to the accumulation of leaf flavonols and leucoanthocyanes and of scale and bark coumarins.     

Incorporation de phenylalanine,de glucose et d'acide cinnamique dans les flavonols de l'oignon

In Allium cepa bulb scales, incorporation of ¹⁴C-phenylalanine, cinnamic acid and glucose were studied in relation to flavonol synthesis. The best incorporation into flavonols is obtained with either cinnamic acid or phenylalanine. ¹⁴C-glucose gives a slow incorporation into flavonol aglycone; this is because there is a big pool of free glucose in the scales in which the precursor is diluted. Under certain conditions, free cinnamic acid is quickly incorporated in a complex which may be a glycoside. After short labelling experiments with phenylalanine or cinnamic acid, some free precursor can be found in the scales a few days later but it is not available for flavonol synthesis. In these conditions, flavonol analysis shows in some cases, no turnover and in others, a turnover of 10% per day due to catabolism.     

Essai d'inventaire bibliographique des algues Dasycladacees du Jurassique et du Cretace inferieur

Bibliographical, geographical and stratigraphical index of all Algae Dasycladaceae describedin Jurassic and Lower Cretaceous from the world.     

Estinnophyton wahnbachense (Kräusel et Weyland) comb. nov., une plante remarquable du siegenien d'allemagne

Specimens collected from the type locality of Protolepidodendron wahnbachense Kräusel et Weyland 1932 (Germany) are studied. The narrow axes, with persistent leaves which are bifurcated and spirally arranged, resemble those of P. wahnbachense. However, the vegetative and fertile leaves bifurcate twice and the four resulting segments are spread in various planes; the fertile leaves support two pairs of stalked elongate sporangia which are directed towards the axis. Estinnophyton wahnbachense (Kräusel et Weyland) comb. nov. is thus proposed as a name for these Siegenian plant remains, the questionable affinities of which are discussed.     

Alcaloides d'Araliopsis soyauxii. Isolement d'un nouvel alcaloide,l'Araliopsine

Six alkaloids have been isolated from root bark of Araliopsis soyauxii. Five are known, maculine, flindersiamine, skimmianine, (?) ribalinine, (+) isoplatydesmine and the sixth, araliopsine is new; its structure has been established as hydroxyisopropyldihydrofuro-2-quinolone. From the trunk bark four alkaloids have been isolated: flindersiamine, kokusaginine (?) ribalinine, (+) isoplatydesmine.     

Polyacetyleniques en C17 des racines d'Heracleum mantegazzianum

Heracleum mantegazzianum roots were examined for polyacetylenes. The structures of two compounds, n-cis-heptadecene-(9)-diyne-(4,6)-ol-(8) and n-trans-cis-heptadecadiene-(2,9)-diyne-(4,6)-ol-(8) are definitively established.     

Alcaloïdes d'Alstonia quaternata

Eleven alkaloids have been isolated from Alstonia quaternata. Three of them, namely 11-methoxy-epi-3α-yohimbine, 10,11-dimethoxy-picrinine designated quaternine, and 19,20-epoxy-N_(a)-methyl, desacetyl, desformo, 2βH-dihydroakuammiline designated quaternoxine, are new alkaloids.     

Données nouvelles sur les mammifères et les nummulites de l'éocène supérieur subalpin (synclinaux du Charbon et d'entrevernes,Bauges, Savoie et Haute-Savoie)

Vertebrate remains and nummulites have been investigated from the Late Eocene—Early Oligocene transgressive sequence of the «Chaînes subalpines south of the lake Annecy. The sedimentary environments range from fluvio-lacustrine shales and conglomerates at the base to hemipelagic Globigerina shales at the top. The fluvio-lacustrine white marls contain mammals of the upper, probably terminal Ludian, with affinities to the assemblage of Saint-Capraise. The brackish Cerithium beds have furnished charophytes of the Bembridge zone. The nummulite limestones are not dated precisely, but isolated, probably redeposited nummulites from the base of the Globigerina shales are of terminal Eocene or basal Oligocene age. The Globigerina shales themselves belong to the Oligocene.     

Variations du taux d'amp cyclique et des activités spécifiques de l'adénylate cyclase et de l'amp cyclique-phosphodiestérase pendant le cycle cellulaire d'un actinomycète

The variations in the concentrations of intra- and extracellular cyclic AMP and in the specific activities of adenylate cyclase (EC 4.6.1.1) and cyclic AMP phosphodiesterase (EC 3.1.4.17) have been monitored in synchronized culture of Nocardia restricta, a prokaryote belonging to the group of Actinomycetes. At the beginning of the cell cycel, during a first period of RNA and protein synthesis, there is an increasing synthesis of adenylate cyclase which can be suppressed in the presence of chloramphenicol or rifampicin. Simultaneously, the specific activity of cyclic AMP phosphodiesterase decreases and the concentrations of intra- and extracellular cyclic AMP rise. After the end of DNA replication, during a second period of RNA and protein synthesis, the specific activity of cyclic AMP phosphodiesterase increases; during the same time, the specific activity of adenylate cyclase and the level of intracellular cyclic AMP drop. It appears that the overall metabolism of cyclic AMP is coordinated so that the cyclic AMP level will be high at the beginning of DNA replication and will fall thereafter. The results are discussed in comparison with known data about the variations of cyclic AMP during the cell cycle of mammalian cells in cultures.