The immunolysis,isolation, and properties of subpopulations of mammalian brain synaptosomes

Five subpopulations of mammalian brain synaptosomes can be selectively damaged by complement-mediated immunolysis employing antibodies to specific surface markers for each subpopulation. This allows the size of these subpopulations to be estimated. Employing antibodies alone, it has proved possible to isolate three of these subpopulations in very pure preparations which are metabolically viable. The immunoaffinity technique involved (immunomagnetophoresis) uses magnetic microspheres and produces mg (protein) quantities of synaptosomes.Special issue dedicated to Dr. Elling Kvamme.     

Absence congenitale des canaux deferents: Phenotype genital de la mucoviscidose?

Because spermatogenesis is typically normal in men with bilateral agenesis of the vas deferens, epididymal sperm recovery for subsequent use in in-vitro fertilization (IVF) has recently been proposed for such patients. The discovery of the presence of mutations in the cystic fibrosis gene in such patients has indicated that this disease might constitute a genital phenotypie concomitant of cystic fibrosis, and has profound genetic implications if the spouse is heterozygous. Testing for mutations of the cystic fibrosis gene, and the provision of genetic counselling as appropriate, should be performed in patients, and their partners, when IVF is being considered for such couples presenting with infertility. The main characteristics of the cystic fibrosis gene and its mutations are discussed, with particular reference to problems in identifying mutations among the 27 exons encoding the gene’s product     

Growth and gas exchange responses of Hevea brasiliensis seedlings to inoculation with Glomus mosseae

 The beneficial effect of arbuscular mycorrhizal (AM) fungi on plant growth is well known, but the physiological processes involved are still discussed. The purpose of this study was to determine if Glomus mosseae affects the growth of Hevea brasiliensis seedlings and, if it is the case, if it could be associated with variations in leaf CO₂ and H₂O gas exchange. H. brasiliensis rubber trees were grown for 9 months in a medium containing either propagules of G. mosseae or sterilized inoculum. Plant size, root collar diameter and leaf area, as well as net CO₂ assimilation, stomatal conductance (g_s) and water-use efficiency of photosynthesis were evaluated during the first 5 stages of growth. At stage 2, a growth depression occurred in the mycorrhizal seedlings coincident with the first AM infections. Then, at stage 5, Glomus mosseae-inoculated plants had moderate colonization (47% of root length) and were taller than control plants with a larger root collar diameter and an enhanced leaf organogenesis. This enhanced growth was accompanied by increased photosynthesis, transpiration, and stomatal conductance. After 9 months, dry weights of shoots and roots of inoculated plants were greater than those of controls by 27 and 17%, respectively. Received: 10 May 1997 / Accepted: 9 September 1997     

Nouvelles observations sur l'anatomie et sur la position systématique d'un poisson téléostéen du Cénomanien du Liban: Pateroperca Woodward

The genus PateropercaWoodward which includes two species, P. libanicaWoodward and P. robusta nov., is described in detail on the basis of acid prepared material from the Cenomanian fish bed of Hadjula (Lebanon). It is demonstrated that Pateroperca does not belong to the Order Ctenothrissiformes contrary to the generally accepted idea. Despite the possession of characters known among Acanthoterygian fishes, it is not possible to show that this genus may be related to the Order Beryciformes and the new family Pateropercidae nov. is left as Ctenosquamata incertae sedis.     

Immunohistochemical studies on a human thymic epithelial cell subset defined by the anti-cytokeratin 18 monoclonal antibody

Summary Two monoclonal antibodies respectively recognizing cytokeratins (CK) 18 and 19 were applied to the human thymic epithelium (in vivo and in vitro) in normal and pathological conditions, including 12 thymomas. We observed that in both normal and hyperplastic thymuses (from patients with myasthenia gravis) virtually the entire epithelial network was CK19-positive as were the majority of cells growing in culture. In four thymomas, however, the expression of cytokeratin 19 was not detected by immunofluorescence. On the other hand, CK18 was expressed by a discrete subset of medullary thymic epithelial cells in normal and in hyperplastic thymuses. Among the thymomas a large majority was either negative or contained few isolated CK18-positive cells scattered within the tumour. Conversely, in the two undifferentiated epithelial thymomas, virtually all the tumoral network was strongly labeled with the anti-CK18 monoclonal antibody. The present investigation thus not only defines the human thymic epithelial cell subset on the basis of differential cytokeratin expression but also indicates that anti-CK antibodies with single cytokeratin specificities can be regarded as useful tools to study the heterogeneity of thymomas.     

Binding of malonate to the inner membrane of rat liver mitochondria

The binding of malonate to the external face of the mitochondrial inner membrane has been investigated by using mitoplasts and on the opposite face, by using inside-out oriented vesicles prepared from sonicated mitoplasts. The external face of the inner membrane displays a single class of binding sites whereas two classes are observed in vesicles. In trypsin treated vesicles, only high-affinity sites are evidenced. The disappearance of the low affinity sites is correlatively related with the loss of succinate dehydrogenase activity. Both high-affinity sites of mitoplasts and vesicles are sensitive to the presence of malate; they are also masked by 2-butylmalonate, phosphate, citrate and mercurials. Our results suggest that the internal and external high-affinity sites of the inner membrane are involved in the dicarboxylate transport system.     

The serum thymic factor (FTS)

Summary The thymus produces a nonapeptide capable of inducing T cell surface markers and T cell functions in immature lymphoid cells. This peptide is found partly bound to a carrier protein in the circulation from where it has been isolated (hence its name of serum thymic factor (FTS)). Immunofluorescence studies using an antibody raised against synthetic FTS has shown that it is produced by the thymic epithelium. Its mode of action at the cellular level involves the binding to specific high affinity receptors.     

Diversity of total and active free-living vs. particle-attached bacteria in the euphotic zone of the NW Mediterranean Sea

The structure of the total and metabolically active communities of attached and free-living bacteria were analysed in the euphotic zone in the NW Mediterranean Sea with the use of DNA- and RNA-derived capillary electrophoresis single-strand conformation polymorphism fingerprinting. More than half (between 52% and 69%) of the DNA-derived operational taxonomic units (OTUs) were common in both attached and free-living fractions in the euphotic layer, suggesting an exchange or co-occurrence between them. However, analysis targeting 16S rRNA showed that only some of them were found in the dominant active bacterial pool. Especially at the deep chlorophyll maximum, less than half of the attached bacterial populations were found to be active, with regard to the high proportion of OTUs present at the DNA level, but not at the RNA level. These results suggest that even if colonization on and detachment of particles appear to be ubiquitous, most of the particulate organic carbon remineralization appeared to be mediated by a rather low number of dominant active OTUs specialized in exploiting such specific microenvironment.     

Piagetian object-permanence in Cebus capucinus,Lagothrica flavicauda and Pan troglodytes

Object-permanence was studied with one chimpanzee (Pan troglodytes) and two New World monkeys (Lagothrica flavicauda and Cebus capucinus). The chimpanzee and the capucinus attained stage VI, while Lagothrica reached stage Va. The data show that tests of object-permanence are suitable for comparison among species. This study also attempts to propose an experimental scheme that could allow for a more valid comparison among species. Use of an operant conditioning procedure is suggested and discussed.