Immunohistochemical analysis of diethylstilbestrol-induced renal tumors in adult male Syrian hamsters: evidence for relationship to peripheral nerve sheath tumors

Estrogen-induced Syrian hamster kidney tumors (SHKT) are widely used as experimental models for the study of hormonal and renal carcinogenesis. In order to characterize the direction of differentiation of SHKT, kidney sections of diethylstilbestrol (DES)-treated hamsters (1-11 months) were analyzed by immunohistochemistry using a panel of lineage-specific markers. The first tumorous buds found in animals exposed to DES for 4-6 months exhibited prominent S100, Leu-7, and vimentin immunoreactivities. Immunopositivities for neuron-specific enolase, PGP 9.5, desmin, and glial fibrillary acidic protein were mostly detected in medium-sized and large tumors after prolonged exposure to DES (> 6 months). All neoplasms, irrespective of the size and the duration of treatment, appeared negative for cytokeratin, neurofilaments, synaptophysin, and CD99 antibodies. Western blotting confirmed to a large extent the immunohistochemical observations. The systematic analysis of serial kidney sections by confocal microscopy after double immunostaining for S100 and neurofilaments revealed that early neoplastic buds could stem from S100-positive cells associated with nerves bundles. Altogether, these observations suggest that DES-induced SHKT could be related to malignant peripheral nerve sheath tumor and originate from a yet unidentified precursor cell present in the sheath of peripheral nerves.     

Wlassicsia,Bunops & Onchobunops (Anomopoda), three related genera

Comparison of the gross morphology and trunk limb ultrastructure of the macrothricid genera Wlassicsia, Bunops and Onchobunops by light and electron microscopy demonstrated their morphological similarity. We propose the synonymy of Onchobunops Fryer & Paggi with Bunops Birge on the basis of shared characteristics.     

Découverte du genre actuelTrigonognathus (Squaliformes: Etmopteridae) dans le Lutétien des Landes (sud-ouest de la France). Remarques sur la denture de l’espèce actuelleTrigonognathus kabeyai

The dental morphology of the Recent squaliformTrigonognathus kabeyai is described and figured in detail for the first time. Some enigmatic teeth recently collected in the Lutetian of Landes (southwestern France) can be interpreted and identified as a new species (T. virginiae n. sp.) thanks to the study of the Recent genus. The discovery of a very specialized genus as early as the Lutetian indicates an early colonization of the bathyal habitat.     

Joint Multipoint Linkage Analysis of Multivariate Qualitative and Quantitative Traits. II. Alcoholism and Event-Related Potentials

The availability of robust quantitative biological markers that are correlated with qualitative psychiatric phenotypes can potentially improve the power of linkage methods to detect quantitative-trait loci influencing psychiatric disorders. We apply a variance-component method for joint multipoint linkage analysis of multivariate discrete and continuous traits to the extended pedigree data from the Collaborative Study on the Genetics of Alcoholism, in a bivariate analysis of qualitative alcoholism phenotypes and quantitative event-related potentials. Joint consideration of the DSM-IV diagnosis of alcoholism and the amplitude of the P300 component of the Cz event-related potential significantly increases the evidence for linkage of these traits to a chromosome 4 region near the class I alcohol dehydrogenase locus ADH3. A likelihood-ratio test for complete pleiotropy is significant, suggesting that the same quantitative-trait locus influences both risk of alcoholism and the amplitude of the P300 component.     

The use of multi-parameter flow cytometry to compare the physiological response of Escherichia coli W3110 to glucose limitation during batch, fed-batch and continuous culture cultivations.

Multi-parameter flow cytometric techniques have been developed for the 'at-line' study of bacterial cultivations. Using a mixture of specific fluorescent stains it is possible to resolve an individual cells physiological state beyond culturability, based on the presence or absence of an intact polarised cytoplasmic membrane, enabling assessment of population heterogeneity. It has been shown that during the latter stages of small-scale (5 l), well mixed fed-batch cultivations there is a considerable drop in cell viability, about 17%, as characterised by cytoplasmic membrane depolarisation and permeability. These phenomena are thought to be due to the severe and steadily increasing stress associated with glucose limitation at high cell densities, during the fed-batch process. Such effects were not found in either batch or continuous culture cultivations. The possibility of using these findings for improved process control using 'on-line' flow cytometry are discussed.     

IpaC induces actin polymerization and filopodia formation during Shigella entry into epithelial cells.

Shigella proteins that are targeted to host cells by a type III secretion apparatus are essential for reorganization of the cytoskeleton during cell invasion. We have developed a semi-permeabilized cell assay that tests the effects of bacterial proteins on the actin cytoskeleton. The Shigella IpaC protein was found to induce the formation of filopodial and lamellipodial extensions in these semi-permeabilized cells. Microinjection of IpaC into cells, or cellular expression of IpaC also led to the formation of filopodial structures. Monoclonal antibodies (mAbs) directed against the C-terminus of IpaC inhibited the IpaC-induced extensions, whereas an anti-N-terminal IpaC mAb stimulated extensive lamellae formation. Shigella induced foci of actin polymerization in the permeabilized cells and these were inhibited by anti-C-terminal IpaC mAbs. Consistent with a role for IpaC in Shigella-induced cytoskeletal rearrangements during entry, stable transfectants expressing IpaC challenged with Shigella showed increased bacterial internalization. IpaC-induced extensions were inhibited by a dominant-interfering form of Cdc42 or the Cdc42-binding domain of WASP, whereas a dominant-interfering form of Rac resulted in inhibition of lamellae formation. We conclude that IpaC leads to activation of Cdc42 which in turn, causes activation of Rac, both GTPases being required for Shigella entry.     

Limnological Aspects of Some Moroccon Atlas Lakes,with Reference to Some Physical and Chemical Variables,the Nature and Distribution of the Phyto- and Zooplankton,Including a Note on Possibilities for the Development of an Inland Fishery

Four mountain lakes were studied. Two are eutrophic, one is mesotrophic and one is oligotrophic. The first three have a well-developed phyto- and zooplankton, with a relatively high diversity index. There are differences between the faunas that may be ascribed to differences in surface, depth, altitude and also to biological phenomena such as interspecies competition. The Ifni Lake is a genuine high-mountain lake, subject to severe environmental conditions. It has a very simple food chain: there is only one species of algae, an unicellular blue-green, one copepod species, one rotifer and one fish. In general some features of a definite interest for fundamental limnology were found: the presence of a pelagic Rhabdocoelid in Dayat Ifrah, some particularities in the vertical distribution of a number of plankton species, the existence of a layer of relatively warm water near the bottom of Lake Ifni. The latter is explained by a strong bottom current which flows through the lake between its phreatic in- and outlets. Finally, stress is laid on the under-exploitment of Moroccon inland waters with respect to a freshwater fishery. Yet, perspectives are good and some suggestions are forwarded.     

Current and future applications of flow cytometry in aquatic microbiology

Flow cytometry has become a valuable tool in aquatic and environmental microbiology that combines direct and rapid assays to determine numbers, cell size distribution and additional biochemical and physiological characteristics of individual cells, revealing the heterogeneity present in a population or community. Flow cytometry exhibits three unique technical properties of high potential to study the microbiology of aquatic systems: (i) its tremendous velocity to obtain and process data; (ii) the sorting capacity of some cytometers, which allows the transfer of specific populations or even single cells to a determined location, thus allowing further physical, chemical, biological or molecular analysis; and (iii) high-speed multiparametric data acquisition and multivariate data analysis. Flow cytometry is now commonly used in aquatic microbiology, although the application of cell sorting to microbial ecology and quantification of heterotrophic nanoflagellates and viruses is still under development. The recent development of laser scanning cytometry also provides a new way to further analyse sorted cells or cells recovered on filter membranes or slides. The main infrastructure limitations of flow cytometry are: cost, need for skilled and well-trained operators, and adequate refrigeration systems for high-powered lasers and cell sorters. The selection and obtaining of the optimal fluorochromes, control microorganisms and validations for a specific application may sometimes be difficult to accomplish.