Alcaloides d'Alstonia lanceolifera

From the aerial parts of Alstonia lanceolifera six alkaloids were isolated and identified: O-trimethoxycinnamoylvincamajine, O-trimethoxy-cinnamoyl-10-methoxyvincamajine, O-trimethoxycinnamoyl-10-hydroxyvincamajine, O-trimethoxybenzoylhydroxyvincamajine, 10-methoxyvincamajine, N(a)-methyl-10-methoxyakuammidine. These alkaloids are new compounds, except for the first. The position of aromatic substituents was determined by study of the Nuclear Overhauser Effect (N.O.E.) in the NMR spectra.     

Trietrpenoides d'Agauria salicifolia

3-acetylmorolic acid, 3-acetylmoradiol, 3-acetylmoraldehyde, taraxerol, taraxerone, sitosterol and agauriasterone, an isomer of nor-31-lanosterone, have been isolated from the methanolic extract of the bark of Agauria salicifolia.     

Epistreptophyllum (Hexacorallaire Jurassique), genre colonialou solitaire? examen d'un matériel nouveau d'Israel

Epistreptophyllum, a rather common coral in the Middle and Late Jurassic of Europe and Asia, is generally regarded as solitary. Some specimens collected in Late Callovian beds of the northern Negev, Israel, show genuine branching which would suggest a colonial habit for this genus. Eventual convergence between the genera Epistreptophyllum, Haplaraea and Diplaraea is presumed.     

Winwaloeusia,genre nouveau d'Acritarche du Devonien

Any Acritarchs that previously were included in the genus Veryhachium (DEUNFF 1954) are transferred in the new genus Winwaloeusia.     

Composes phenoliques du latex d'Hevea brasiliensis: aglycones

The latex of Hevea brasiliensis; clone PR 107, contains from 160 to 1100 μg total phenolics per ml. This wide variability is associated with season, tapping system and application or not of a stimulant (Ethrel). The following aglycones have been identified in hydrolysed extracts: vanillic, salicyclic, syringic, gentisic, p- and m-hydroxybenzoic and protocatechuic acids; scopoletin, aesculetin and coumarin; ferulic, sinapic, caffeic, o- and p-coumaric acids; quercetin and kaempferol; tyrosine and dihydroxyphenylalanine. Flavans and condensed tannins are also present in latex.     

Isoenzymes de l'anhydrase carbonique d'un poisson euryhalin: Variations en relation avec l'osmoregulation

A chemical study of carbonic anhydrase (EC 4.2.1.1) from the red blood cells and the gills of an euryhaline fish (Anguilla anguilla) is presented. Animals adapted to fresh water were compared to those adapted to sea water.The physicochemical constants of the various molecular forms isolated by chromatograhy and isoelectric focusing were determined; isoeleletric pH, molecular weight, and the K_m and V/E of the enzyme dehydration activity were compared.In both red cells and gills of fish adapted in either media various forms were isolated, characterized by different enzymatic kinetics (high- and low-activity forms) but having the same molecular weight (27 250). Some isoenzymes isolated from the gills differed significantly from those isolated from the red cells.Adaptation to fresh water or sea water is accompanied by modifications in the distribution of yhe isoenzymes in both red cells and gills: adaptation to sea water is characterized by a shift of the molecular forms towards an isoelectric pH higher than pH = 6.The role of these enzymes is discussed under both a physiological and biochemical point of view in relation to the electrolyte exchange across fish gill. The origin of the different molecular forms of the carbonic anhydrase is discussed in relation to the prevailing theories on this subject.     

Alcoxyhalogenation d'acides gras acetyleniques vrais ou disubstitues

Reaction of t-butyl hypobromite (HBBT) with true or disubstituted acetylenic fatty acids leads to the formation of gemdimethoxy gemdibromides, resulting from the addition of two mol of HBBT upon each mol of substrate. Neither digemmethoxybromide nor vinylic methoxybromide, resulting from the addition of only one mol of HBBT, are formed.If the triple bond is a terminal one, only the Markovnikov addition compound is formed but if the triple bond is located in the middle of the chain, the both possible isomers are present.     

Révision taxonomique du genre d'ammonite téthysien Simoceras et création d'un nouveau genre Volanoceras (Ammonitina,Simoceratidae)

The type-species of the genus SimocerasZittel isS. biruncinatum (Qu.). This genus includes the species-group biruncinatum (Qu.) — admirandum (Zitt.). The new genus Volanoceras is created for the volanense (Opp.) species-group which is excluded from the genus Simoceras.     

Alcaloïdes d'Ochrosia miana: Ochromianine et Ochromianoxine

The structure of ochromianine and ochromianoxine two new alkaloids isolated from the barks of Ochrosia miana are deduced from spectral analysis.     

Alcaloïdes des feuilles et écorces de tronc d'Alstonia odontophora

Six known indole alkaloids were isolated from the leaves and stem bark of Alstonia odontophora: vincamajine, 11-methoxy- akuammicine, quebrachidine, pleiocarpamine, antirhine, pleiocorine and pleiocraline, along with the novel bisindole, N (I′)-demethylpleiocorine.     

Regulation d'activité de l'α-Amylase à différentes températures d'adaptation et en fonction de l'ablation des pédoncules oculaires et du stade de mue chez Palaemon serratus

The influence of thermal acclimatisation of the shrimp Palaemon serratus on the specific activity of α-amylase and the soluble proteins of the hepato pancreas show the presence of a metabolic compensation kinetic within this organ. The kinetic properties of partially purified α-amylase show that 2 sites are able to fix starch in the absence of NaCl but only 1 site when NaCl is present. The importance of conformational changes of the enzyme is shown by examining its regulatory properties according to the different temperatures of adaptation, and to the removal of eyestalks and the molt cycle. During these changes there are no qualitative variations in α-amylase isoenzymes.     

Une nouvelle espece d'algue dasycladale: Terquemella concava nov. sp., dans les calcaires a “tubulures” d'age portlandien de la Cluse-des-Hopitaux (Jura meridional)

In the portlandian limestones of the southern Jura mountains (Cluse-des-Hôpitaux), a dasyclad algae level provides a new species: Terquemella concava nov. sp., characterized by its sub-hemipheroidal shape. The type-level is made up of a burrowed biomicrite. The in-filling of the burrows consists of grains with meniscus cements, attesting of a vadose diagenesis of the bed.     

Note preliminaire concernant la decouverte d'une faune et d'une flore du niveau de Ronzon dans l'Oligocene inferieur du Bassin d'Aquitaine

The new locality of Ruch (Gironde), from a lateral facies of the “Calcaire de Castillon” formation has yielded an important flora and fauna. From the biostratigraphic point of view the mammalian fauna allows to show that Ruch is contemporaneous of the reference locality of Ronzon (Auvergne).     

Synthesis of polyhalo acridones as pH-sensitive fluorescence probes

Polyhalo isophthalonitriles were reacted with substituted anilines and subsequently cyclocondensed in the presence of sulfuric acid to give polyhalo acridones. These polyhalo acridones were proven to be useful as pH-sensitive fluorescent probes for a wide range of acidic and basic conditions.     

Psychochaetetes (Varioparietes) lucentius nov. sp. (Cnidaria,chaetetida) du Tortonien superieur de la Sierra del Gorda (Nord d'Elche,province d'Alicante,Espagne)

The occurence of Ptychochaetetes (Varioparietes) lucentius nov. sp. in the Upper Tortonian from Sierra del Gorda(North of Elche, Spain) lets to hope the discovery of younger organisms.     

Trilobites d'affinité bohémienne dans l'Éodévonien des Pyrénées centrales françaises

In the upper Adour valley, a series attributed to the Carboniferous yield conodonts and a variegated trilobite fauna with exclusively bohemian affinity. The trilobite fauna is represented by six families, the most of them being described in the Pyrénées for the first time. Trilobites indicate the Praguian whereas conodonts upper Lochkovian-Praguian age. A new unnamed subspecies of Crotalocephalus sternbergi (Boeck, 1827) is described.     

Indications de l'ultrastructure d'une espèce de forme du crétacé supérieur,Oculopollis maximus W. Krutzsch

Some varieties of the pollenform species Oculopollis maximus Krutzsch have been studied by means of transmission and scanning electron microscopy. Contrary to the observations made by means of light microscopy, major differences appear between those with a psilate exine and the others with a sculptured exine. This result makes it clear that the Oculopollis maximus pattern could be a network phyletic system rather than a single phylogenetic line.     

Modalités de la contamination d'une chaine trophique marine benthique par l'argent 110 m: 4. Influence du mode de contamination sur l'élimination du radionucléide

The elimination of ^110mAg by Navicula incerta Grunow ex Van Heurck, Navicula biskanteri Hustedt, Scrobicularia plana (da Costa) and Carcinus maenas (L.) depends upon the duration of contamination or the number of intakes of radioactive food. The longer the contamination occurred, the slower will be the climination.The decontamination is slower after (chronic) ingestion of radioactive food than after immersion in contaminated water. The physico-chemical forms of ^110mAg likely play a rôle in elimination kinetics. So, external organs, whose contamination results mainly from adsorption, get rid of ^110mAg faster than the digestive gland in which silver seems to be retained in a hardly exchangeable form.Consequently, the total radiation dose for contaminated organisms will depend greatly upon the way and the duration of the contamination.