Préparation et forme sérique de la protéine réactive C de lapin

The preparation of rabbit C-reactive protein (CRP) involves a single step affinity chromatography. This preparation takes advantage of the calcium-dependent affinity of CRP for an agarose gel bearing 2-aminoethanol dihydrogen-phosphate as a ligand. A prior chromatography on agarose gel without the ligand allows the uptake of the serum amyloid P-component (SAP).The CRP prepared according to this method is able to form precipitating complexes in agarose with rabbit lipoproteins. The specificity of these interactions is studied. It is demonstrated that CRP-High Density Lipoproteins (HDL) association produces a second precipitation arc when the pure CRP is revealed by a specific antiserum in agarose. Moreover, CRP in the serum is shown to be in the bound form only, and the binding involves Low Density Lipoproteins (LDL) exclusively.     

Structure et composition chimique élémentaire de quelques coquilles d'œufs de dinosaures du Jurassique et du Crétacé d'Amérique du Nord

Structure and chemical composition of some dinosaur eggshells from Jurassic and Cretaceous of North America. Microstructural analyses of some dinosaur eggshells from Jurassic and Cretaceous sites of North America show a large variability in the state of preservation. Outer and inner surfaces are often hidden by secondary deposits, and the tubercles or ridges and spherolites are not visible. Chemical analyses show that some fragments are strongly enriched in Si. There is a good correlation between the preservation of the structures and the chemical contents. Diagenetic processes are different from those described in the samples from Southern France.     

Les Spatangus du Miocène et du Pliocène de l’Ouest de la France

Numerous fragments of spatangoid echinoids have been discovered in the Pliocene deposits of Challans, in Vendée (western France). In spite of the fragmentary data of the samples, a reconstitution of a complete test could be realized using the different fragments and their symetrization. The general shape of the test, and its architectural and ornemental characters allow establishing the presence of the genus Spatangus in western France during the end of Neogene. It allows to precise the biogeography of the genus Spatangus and of the morphological group S. (S.) purpureus on the Atlantic coast after the Messinian crisis. The Pliocene species is compared to the Miocene Spatangus (Phymapatagus) brittanus, abundant in Anjou, Brittany and Touraine. This older species was refered to the subgenus Phymapatagus according to the presumed lack of primary tubercles on its posterior interambulacrum. The discovery of well-preserved specimens, with primary tubercles on every parts of the test, in the Middle Miocene of Brittany allows to refute this subgeneric distinction and to refer the species brittanus to the subgenus Spatangus (Spatangus). The presence of this subgenus in western France is finally confirmed from Middle Miocene to Pliocene.     

Le genre d'échinide s dans les dans les localités du Pliocène et du Pléistocène d'Emilie (Italie du Nord)

The study of well-preserved Pliocene and Pleistocene s from Emi from Emilia is used to analyze the morphological variations of Mediterranean populations, to depict the relationship between fasciole shape and other morphological characteristics and to describe previously unpublished pedicellar valves. These new data allow to be two species distinguished: s (Müller) a (Müller) and s Pomel; six s Pomel; six species closely related to s are synonymi are synonymized: s and it and s Pomel, i Pomel, i and itS. and s Checchia-R Checchia-Rispoli, x Simonelli a Simonelli and the recent species from Mediterranean, s Mortensen Mortensen. s can be disti can be distinguished from s by its hear by its heart-shaped subanal fasciole, when the s one is reni one is reniform. Moreover, the frontal groove of s is deeper, t is deeper, the primary tubercles of the interambulacra 1 and 4 are less numerous, the petals are shorter and narrower, the labrum is shorter. As far as pedicellariae are concerned, the jags of the large tridentate ones are stronger and the base of the globiferous ones is bigger. Palaeoecological observations on outcrops of the Stirone River, in Parme region, show similar environmental affinities between fossil populations and recent populations from Mediterranean. The s fossils fossils seem to be preserved within their life environment, that is to say in shore sandy substrates.

Résumé

L'étude d'un groupe de spécimens bien conservés appartenant au genre Spatangus, trouvés, dans des localités pliocènes et pléistocènes de l'Émilie, permet d'exposer l'étendue de la variation dans les populations fossiles méditerranéennes, de rechercher les relations entre la forme du fasciole sous-anal et les autres caractères morphologiques et de décrire les valves des pédicellaires, qui n'étaient pas connues jusqu'alors. Ces nouvelles données conduisent à reconnaître deux espèces différentes : s (Müller) e (Müller) et s Pomel ; six Pomel ; six espèces voisines de s doivent prob doivent probablement tomber en synonymie : s et itS et s Pomel, i Pomel, i et itS. a et s Checchia-R Checchia-Rispoli, x Simonelli e Simonelli et l'espèce vivant actuellement en Méditerranée, s Mortensen Mortensen. Des observations paléoécologiques sur un échantillon fossile récolté sur les bords de la rivière Stirone près de Parme montrent des affinités bionomiques semblables chez les populations fossiles et celles vivant en Méditerranée.     

Présence des enzymes catalysant la biosynthèse d'UDP glucose dans une fraction légère de l'appareil de Golgi des hépatocytes de chat

A Golgi-rich fraction is prepared from cat hepatocytes by the means of a four-step sucrose density gradient. The material applied to this gradient is composed either of smooth microsomes prepared from healthy animals, or of total microsomes prepared from cat treated by 50 per cent ethanol (0.6 g/100 g body weight, administered by stomach tube).A light fraction (d : 1.10) is obtained by the two procedures. It does not show any glucose-6-phosphatase activity, but is enriched in sialyltransferase, known as a marker enzyme for Golgi apparatus. It also contains the three enzymes implicated in the biosynthetic pathway for UDP-glucose (glucokinase, phosphoglucomutase and UTP : glucose-1-phosphate uridylyltransferase).UDP-glucose being the ultimate substrate in membranous glucosylation reactions, these results could support the hypothesis that sugar-nucleotides necessary for the glycoprotein biosynthesis are produced in the Golgi vesicles directly.     

Patines et cortex de météorisation de grès du site rupestre d’Oum La Leg (Anti-Atlas, Maroc)

Within the framework of the European Commission's program “Patine du Desert” (DG Research; INCO-CT-FP6-2004-509100), partially concerning the preservation of Saharan engraved rock art, the approach led to the study of the sandstone patina from the rock art site of Oum La Leg (Anti-Atlas, Morocco). The rock and its Tazina school engravings are sometimes covered with a thin brown-ochre coating which only shows a dark patina, the desert patina. This film corresponds to a weathering cortex whose formation is contemporary with wet events from the Holocene period. On the surface, the patinas’ diversity is linked to the heterogeneous distribution of manganese oxides (birnessite and todorokite) due to a reorganisation which led to the incorporation of aeolian silts. Some dating suggestions are made to establish an ante quem age for the engraved lines.     

Mesure des déclins de l'intensité et de l'anisotropie de fluorescence du pérylène en présence de membranes d'érythrocyte de pigeon: Comparaison avec un milieu isotrope visqueux

Using synchrotron radiation as the excitation light, we studied the fluorescence parameters of perylene incubated with pigeon erythrocyte membranes and with an isotropic viscous medium, the Primol 342 oil.From 4 to 37°C, we observed a single lifetime of 4.5 ns in the oil and two with the membrane (τ₁ = 1−1.4 ns and τ₂ = 5.4−6.1 ns). The dependence upon temperature of the rotation correlation time of perylene () in the oil was characteristic of an isotropic medium, whereas the limiting value of anitropy (r ∞) was zero. With the membrane, γ ∞ decreased from 0.14 to 0.06 and from 2.9 to 0.5 ns, indicating a greater amplitude and frequency of molecular motions.The addition of chlorpromazine, indomethacine, tetracaine, n-octylamine, octanol or octanoic acid to the membrane decreased the τ₁ and τ₂ values. This would stem from the desorganization of the membrane induced by the drugs.     

Pigments biliaires des lépidoptères: Identification de la phorcabiline I et de la sarpédobiline chez diverses espèces

Investigations on blue-green pigments of insects have shown the presence of three main bile pigments in Lepidoptera: pterobiline (the most frequent), phorcabiline I and sarpedobiline.

Résumé

Les recherches que nous poursuivons sur les pigments bleu-vert des insectes montrent l'existence chez les Lépidoptères de trois pigments biliaires principaux; la ptérobiline (la plus fréquemment rencontrée), a phorcabiline I et la sarpédobiline.     

Isolement et identification de composés à activité phéromonale chez les femelles de l'arctiide Tyria jacobaeae: Détermination biologique de la configuration absolue du composé majoritaire

Les analyses physico-chimiques d'extraits hexaniques de glandes à phéromone de femelles vierges de T. jacobaeae, associées à des études du comportement sexuel et à l'électroantennographie, ont permis d'identifier le composé majoritaire (98%) comme étant l'époxy-9S,10R-(Cis)-hénéicosadiène-3Z,6Z (n^o 1) et de déterminer sa configuration absolue. Les analogies entre les spectres du composé n^o 2 (1,5%) et ceux de l'époxy-9S,10R éicosadiène-3Z,6Z de synthèse nous conduisent à proposer cette structure pour ce constituant minoritaire. Le troisième produit (0,5%) possède les caractéristiques physico-chimiques de l'hénéicosatriène-3Z,6Z,9Z (n^o 3). Les produits 1 et 3 ont déjà été identifiés comme constituants de phéromones d'Arctiidae tandis que le produit 2 est décrit ici pour la première fois dans une sécrétion phéromonale de Lépidoptère.     

Groupement et ordination appliqués à l''étude de la répartition de l''épifaune benthique de l''estuaire maritime et du Golfe du Saint-Laurent

Forty-seven navigation buoys were used to collect quantitative samples of epibenthic fauna in the Lower Estuary and Gulf of St. Lawrence. Stations, as described by their sessile species and biomass composition, were grouped using multivariate analysis. A Gower similarity index, modified to take into account the importance of each species in the ecosystem, was used to compare stations. Results obtained by cluster and principal coordinate analyses showed comparable relations between stations. North Shore and Gaspé Coast stations were separated from those of the Lower North Shore, the Mingan Island sector and the Lower Estuary. Stations from the Lower North Shore were also separated from those of the Mingan Island region and of the Lower Estuary, but at a higher level of similarity. All animal assemblages consisted of the following sessile species: Obelia longissima (Pallas), Hiatella arctica (L.), Mytilus edulis L., Balanus balanoides (L.) and B. crenatus (Bruguière). These species formed over 95% of biomass of all sessile species. Differences between the various station assemblages were mainly due to changes in the relative abundance of these species. The geographical gradient of summer surface water temperature best explains the observed clusters. In the Lower Estuary, the spatio-temporal variations of physico-chemical factors and the surface circulation may influence the number of species and their abundance. The circulation systems of the Lower Estuary and near the Mingan Islands might account for the similarity between their assemblages. The same dominant species, Obelia longissima, characterizes the fauna of these two regions.     

Quelques aspects du métabolisme des acides gras à longue chaîne par les cellules bathmotropes de cœur de rat en culture

As a preliminary to the study of the metabolism of erucic acid by beating heart cells of post natal rats in culture, the activity of lipoprotein lipase and the oxidation of palmitic acid have been studied. The results have led us to use 14 day cultures as the material of choice for experiments on the incorporation of erucic acid into cardiac cells, and on its subsequent distribution into different classes of lipid. Work on fatty acid oxidation has been carried out on 5–8 day cultures.We have shown that erucic acid enters cardiac muscle cells, but that the cells are not capable of oxidizing it directly.We have suggested two independent mechanisms by which this is done, namely shortening of the chain followed by the complete utilization of this smaller molecules by β-oxidation. The delay which this implies would explain the accumulation of erucic acid in the heart cells.We have also proposed that the accumulation of large quantities of erucic acid in phospholipids and esters of cholesterol may modify the structure of cellular and mitochondrial membranes, thus explaining the pathological effects of erucic acid.