Immunohistochemical localization of a gastrin-like peptide in the brain of an amphibian,Xenopus laevis Daud.

Summary The indirect immunofluorescence technique was used to demonstrate a substance reacting with gastrin antisera in the brain of Xenopus laevis.Immunoreactive material was found in two sites: (1) In the caudal hypothalamus more precisely in the nucleus infundibularis ventralis, (NIV) of the pars ventralis of the tuber cinereum, (PVTC). The fluorescent axons of the reactive parikarya of the NIV give rise to two symmetrical tracts which run rostro-ventrally and join, in the infundibular floor, the preoptico-hypophysial tract, where they form an uneven median tract coursing caudally and running along the medio-tuberal area before entering the external zone of the median eminence. (2) In the anterior preoptic area (APOA), where numerous nerve fibers and endings form a dense network near the preoptic recess. The exact origin of these terminals has not yet been determined.Control of immunohistochemical specificity shows that the labeling by gastrin antisera is suppressed by gastrin (2–17), but also by cholecystokinin (CCK) and pentagastrin (Peptavlon). These results indicate that the immunoreactive substance revealed belongs to the gastrin group and has an antigenic determinant composed of the amino acid sequence or a portion thereof common to gastrin, CCK and Peptavlon (Trp-Met-Asp-Phe).It should be emphasized that, in the brain of Xenopus laevis, both gastrinimmunoreactive sites correspond to the sites of uptake of steroid hormones (Kelley et al., 1975; Morrell et al., 1975).Supported by the D.G.R.S.T., Contrat n 77.7.0648     

Réflexions critiques sur l'écologieet la systématique des Lingules actuelles et fossiles

New topics on ecology and systematics of recent and fossil Lingulids lead to an obvious revision of our knowledges on this zoological group. At first, the recent species need systematics and taxonomy on the bases of new described specific criteria (as, morphology of deltidial areas, muscle disposition); the results are briefly indicated. But, in fossil species, disorder and disparity of used characteristics are emphasized.The general conceiving on ecology of Lingulids are reviewed and discussed, especially on bathymetry and salinity; sediment and oxygenation conditions; taphocoenosis and lingulid «communities. On recent species, all these points are also studied, especially some ecological requirements (salinity, bathymetry, grain size), and mechanism of burrowing ability, burrow living positions in the sediments, as shell preservations after death and fossilization, to facilitate the paleobiotope interpretations. Recent animals are euryhalin, surviving at salinities from about 13 to 42‰; they could be considered as well adapted to waters with strong salinity fluctuations. They show preference to fine sand bottoms (lowest particle size about 40–60 μm). Their bathymetric distribution occurs between 0 and about 500 m (Lingula especially between 5–50 m; Glottidia 15–70 m). The isotherms 8–10°C seem to restrict their geographical and bathymetric distribution.Therefore, some post-palaeozoic lingulid bedsare studied or redescribed on the bases of the above discussed characteristics, and new interpretations on the environmental situation are given (Trias of Vosges Mountains; Oligocene from Japan; Eocene of London Basin). More caution must be used in study of fossil Lingulids that are not especially animals living in infralittoral bottoms with low salinity and deficient oxygenation, as generally accepted.     

Mitochondrial protein alteration in active brown fat: A sodium dodecyl sulfate-polyacrylamide gel electrophoretic study

The polypeptide composition of mitochondria isolated from the brown adipose tissue of control rats (bred at 22°C) or cold-exposed animals (bred at 6°C) was compared using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A striking increase in the content of an unknown polypeptide (apparent molecular weight 32,000 daltons) was found after cold adaptation, a phenomenon which was reversed during re-adaptation to a normal temperature. This protein seems to be localized in the membrane fraction of the mitochondria.     

Régulation et signification physiologique de l'aspartate-ammonium lyase (aspartase) de Pseudomonas fluorescens type R

The biosynthesis of aspartate-ammonium lyase, the enzyme which is induced by aspartic acid, is specifically repressed by fumaric acid. In the presence of aspartate, the enzyme permits the deamination of this compound by the cell. Aspartic acid is converted into fumaric acid which is an intermediate in the Krebs'cycle. The reaction may be considered as an anaplerotic sequence. In the absence of aspartic acid in the culture medium, its role is anabolic; the enzyme catalyses the biosynthesis of this amino acid. Therefore it appears that the reversible reaction fumarate+NH₃=aspartate catalysed by aspartase is included in amphibolic processes.     

Anti-hypertensive effects of Rosuvastatin are associated with decreased inflammation and oxidative stress markers in hypertensive rats

Among their pleiotropic effects, statins exert antioxidant and anti-inflammatory properties. The aim of this study was to evaluate in normotensive (WKY) and in spontaneously hypertensive rats (SHR) the effect of rosuvastatin (ROSU) treatment on (1) plasma inflammation markers and endogenous NO synthase inhibitor (ADMA) levels, (2) reactive oxygen species (ROS) generated by circulating leukocytes and (3) vascular oxidative stress and tissue inflammation markers. Plasma cytokines were higher in SHR than in WKY, except for IL-4, which was lower in SHR than in WKY. SHR monocytes exhibited higher production of ROS than did WKY monocytes. In the experimental conditions, ROSU did not modify plasma cholesterol levels in SHR but attenuated the increase in systolic blood pressure. In SHR only, ROSU lessened pro-inflammatory cytokines and ADMA levels, increased IL-4 and reduced ROS production in circulating monocytes. These results demonstrate the beneficial effects of ROSU in SHR, independently of any lowering of cholesterol levels.     

Synthesis and Biological Evaluation of a New N4-(N-Formyl Peptide)- 2′,3′-Dideoxy-3′-Thiacytidine as Anti-Hiv Prodrug

Abstract

The synthesis of a new analogue of 2′,3′-dideoxy-3′-thiacytidine 9 covalently linked to an N-formyl methionyl leucyl phenylalanine peptide is described. This new prodrug analogue has been tested on the one hand as activator of human polymorphonuclear leukocytes (an EC₅₀ value of 1.8 10^?5 M was determined from dose-response curve for superoxide production) and on the other hand as inhibitor of the syncitium formation caused by HIV-1 in MT4-cells (IC₅₀ = 8.0± 0.8 μM). In so far as this new prodrug possesses these two biological properties, it represents a useful “chemical-head” capable of targeting specific receptors located on leukocytes membranes.     

Metallothionein concentration in the mussel Mytilus galloprovincialis as a biomarker of response to metal contamination: validation in the field

Mussels were translocated from a shell-fish breeding area (Sète, on the French Mediterranean coast) to sites exposed to trace element inputs in April 2000. They were recovered 3 months later. Whole soft tissues from all of the sites (n = 97) were analysed for arsenic, cadmium, chromium, copper, mercury, nickel, lead and zinc. Metallothioneins (MTs) were also measured in the digestive gland and in the remaining tissues (allowing calculation of whole soft tissue concentrations) at 22 of the 97 sites. MT concentrations in the digestive gland and the whole soft tissues were strongly correlated. The condition index varied with food availability at different sites. This did not influenced MT concentrations in the whole soft tissues, whereas the condition index was negatively correlated to trace element concentrations. A model is proposed to minimize this influence of condition. Metal concentrations adjusted using this model showed significant correlations with MT levels for those metals (cadmium, copper, nickel and zinc) that are known to bind to this protein, with the exception of mercury. Even in moderately contaminated sites, measurement of the MT level in the soft tissues of mussels was generally able to discriminate between different levels of contamination, allowing the use of a simplified procedure compared with dissection of the digestive gland. It is recommended to avoid translocation and sampling during the reproductive period, which is well documented for commercial species such as Mytilus sp.