Découverte de charophytes et ostracodes de l’Yprésien inférieur dans les Monts des Ksour (Algérie) : biostratigraphie et paléoécologie

A stratigraphic, palaeontological and sedimentological study was carried out in the red beds cropping out on the left side of Oued Tafarahit, south-east of the Ksour Mountains (Algeria). The studied succession consists of a non-marine fining-upward detrital formation, including microconglomerate, sandstone and clay beds, which were previously attributed to the Cenozoic sensu lato, since no palaeontological evidence was available. Sedimentology suggests deposition in a fluvial environment. The clayey levels yielded the assemblage formed by the charophytes Peckichara atlasensis, Maedleriella cristellata, Nitellopsis (Tectochara) thaleri, Grovesichara sp., and Lamprothamnium papulosum and the ostracods Neocyprideis meguerchiensis, Herpetocypris? sp. and Cyprinotus? sp. This assemblage allows constraining the age of the detrital series from Oued Tafarahit to the Ypresian. Ostracods are typical of freshwater to euryhaline environments. The freshwater taxa (Herpetocypris? sp. and Cyprinotus? sp.) would indicate phases of desalinisation during periods of flood. However, the brackish water species (Neocyprideis meguerchiensis) is characteristic of saline phases related to low water table periods. Moreover the charophyte and ostracod assemblage confirms a close palaeobiogeographic relationship between North Africa and Southern Europe during the Lower Eocene.     

Suitability for classical biological control of Hedychium coronarium in Argentina

BioControl - Hedychium coronarium (Zingiberales: Zingiberaceae), native to the Himalayas and southern China, has become an environmental weed in many countries around the world. Reported in several...     

Alder forests of Numidia (N.E. Algeria): floristic biodiversity, vulnerability and conservation

The phytoecological study of the alder forests of north-east Algeria shows that these habitats with boreal affinities harbour very high species richness (> 400 species) and complex structures, which suggest their ancient origin. They correspond phytosociologically to two syntaxa, the Campanulo alatae-Alnenion glutinosae (riparian alder forests) and the Rusco hypophylli-Alnetum glutinosae (peat-forming alder carrs), respectively. Their degraded state and their regressive dynamics, observed during the 14 years of the study, reveal their precarious situation and their rapid ongoing decline under the influence of human-induced uncontroled disturbances (cutting, burning, draining, dumping…). With regard to their ecological, historical and patrimonial importance, the alder forests of Algerian Numidia should be urgently protected, with the aim of assuring the perennity of their exceptional floristic corteges.     

Sibling relationships in Dutch and immigrant families

This study examines differences in sibling relationships among native Dutch and immigrant groups in the Netherlands. It uses a large national dataset to compare adult sibling relationships among Moroccan, Turkish, Caribbean and native Dutch groups, focusing on the varying importance of gender composition and age structure for the sibling relationship in the ethnic minority groups and the native Dutch families. Results show that, on average, ethnic minorities in the Netherlands have more involved sibling relationships in adulthood, with more contact, more emotional support, practical support (except Turks and Antilleans), a higher relationship quality, but also more conflict (among the Turks and Antilleans) compared to the Dutch. Gender constellation and hierarchical position were not of equal influence in all groups, although no clear patterns emerged.     

Characteristics of a phylogenetically ambiguous,arsenic-oxidizing <Emphasis Type="Italic">Thiomonas</Emphasis> sp., <Emphasis Type="Italic">Thiomonas arsenitoxydans</Emphasis> strain 3As<Superscript>T</Superscript> sp. nov

A moderately acidophilic, facultative chemoautotrophic, As(III)-oxidizing Thiomonas sp. (strain 3As^T) was previously shown, on the basis of comparative 16S rRNA gene sequences, to be closely related to both Tm. perometabolis DSM 18570^T and Tm. intermedia DSM 18155^T. While it had shared many physiological traits with Tm. intermedia ^T, a mean DNA–DNA hybridization value (DDHV) of 47.2% confirmed that strain 3As^T was not a strain of Tm. intermedia, though the situation with regard to Tm. perometabolis (DDHV previously determined as 72%) was more ambiguous. A comparative physiological and chemotaxonomic study of strain 3As^T and Tm. perometabolis ^T was therefore carried out, together with multilocus sequence analysis (MLSA) of all three bacteria. Differences in fatty acid profiles and utilization of organic substrates supported the view that strain 3As^T and Tm. perometabolis are distinct species, while MLSA showed a closer relationship between strain 3As^T and Tm. intermedia ^T than between strain 3As^T and Tm. perometabolis ^T. These apparent contradictory conclusions were explained by differences in genome of these three bacteria, which are known to be highly flexible in Thiomonas spp. A novel species designation Thiomonas arsenitoxydans is proposed for strain 3As^T (DSM 22701^T, CIP 110005^T), which is nominated as the type strain of this species.     

Recovery of viable cells from rabbit skin biopsies after storage at ?20°C for up to 10?days

Frozen animal tissues are thought to be appropriate for use as a donor for somatic cell nuclear transfer. This makes the freezing for long term storage a valuable tool for breeders needing to protect an animal population that is endangered by sanitary problems or for cryobanking of genetic resources. We report the successful cryopreservation of explants of skin derived from small biopsies from rabbit ear biopsies by using a protocol that can be easily performed by usual breeders, which are not equipped with cooling devices. By optimizing the procedure, we show that small biopsies can be kept at -20°C in a physiological solution containing 10% DMSO for up to 20 days before being deeply frozen in liquid nitrogen for long-term storage. After 10 days of storage at -20°C, the rate of viability of biopsies was similar to the control one (86 and 82% respectively). After 20 days of storage at -20°C, the rate of viability was dramatically lowered (39%), but it still allows to recover a significant population of viable cells from the preserved sample. Being appropriate to places lacking specific device, such a very simple technique may contribute to facilitate genome banking policies dedicated to the management of genetic resources in wild and domestic animals.     

Protoplast Fusion in Banana (<Emphasis Type="Italic">Musa</Emphasis> spp.): Comparison of Chemical (PEG: Polyethylene Glycol) and Electrical Procedure

Optimization of protoplast fusion parameters is a prerequisite for the establishment of somatic fusion technology for banana breeding. In the present investigations, we compared the most frequently used fusion methods: the electrofusion technique and chemical procedure (polyethylene glycol). With regard to frequency of binary fusion, protoplast fusion with the fusogen polyethylene glycol was best. Conversely, electric fusion was found to be better with respect to mitotic activities, somatic embryogenesis and plantlet regeneration rate.     

Galpha13 stimulates cell migration through cortactin-interacting protein Hax-1

Galpha13, the alpha-subunit of the heterotrimeric G protein G13, has been shown to stimulate cell migration in addition to inducing oncogenic transformation. Cta, a Drosophila ortholog of G13, has been shown to be critical for cell migration leading to the ventral furrow formation in Drosophila embryos. Loss of Galpha13 has been shown to disrupt cell migration associated with angiogenesis in developing mouse embryos. Whereas these observations point to the vital role of G13-orthologs in regulating cell migration, widely across the species barrier, the mechanism by which Galpha13 couples to cytoskeleton and cell migration is largely unknown. Here we show that Galpha13 physically interacts with Hax-1, a cytoskeleton-associated, cortactin-interacting intracellular protein, and this interaction is required for Galpha13-stimulated cell migration. Hax-1 interaction is specific to Galpha13, and this interaction is more pronounced with the mutationally or functionally activated form of Galpha13 as compared with the wild-type Galpha13. Expression of Hax-1 reduces the formation of actin stress fibers and focal adhesion complexes in Galpha13-expressing NIH3T3 cells. Coexpression of Hax-1 also attenuates Galpha(13)-stimulated activity of Rho while potentiating Galpha13-stimulated activity of Rac. The presence of a quadnary complex consisting of Galpha13, Hax-1, Rac, and cortactin indicates the role of Hax-1 in tethering Galpha13 to the cytoskeletal component(s) involved in cell movement. Whereas the expression of Hax-1 potentiates Galpha13-mediated cell movement, silencing of endogenous Hax-1 with Hax-1-specific small interfering RNAs drastically reduces Galpha13-mediated cell migration. These findings, along with the observation that Hax-1 is overexpressed in metastatic tumors and tumor cell lines, suggest a novel role for the association of oncogenic Galpha13 and Hax-1 in tumor metastasis.     

Protein kinase C β inhibition by enzastaurin leads to mitotic missegregation and preferential cytotoxicity toward colorectal cancer cells with chromosomal instability (CIN)

Enzastaurin is a selective inhibitor of protein kinase C β and a potent inhibitor of tumor angiogenesis. In addition, enzastaurin shows direct cytotoxic activity toward a subset of tumor cells including colorectal cancer cells (CRC). In spite of promising results in animal models, the clinical activity of enzastaurin in CRC patients has been disappointing although a subset of patients seems to derive benefit. In the present study we investigated the biological and cytotoxic activities of enzastaurin toward a panel of well-characterized CRC cell lines in order to clarify the mechanistic basis for the cytotoxic activity. Our results show that enzastaurin is significantly more cytotoxic toward CRC cells with chromosome instability (CIN) compared to cells with microsatellite instability (MSI). Since CIN is usually attributed to mitotic dysfunction, the influence of enzastaurin on cell cycle progression and mitotic transit was characterized for representative CIN and MSI cell lines. Enzastaurin exposure was accompanied by prolonged metaphase arrest in CIN cells followed by the appearance of tetraploid and micronuclei-containing cells as well as by increased apoptosis, whereas no detectable mitotic dysfunctions were observed in MSI cells exposed to isotoxic doses of enzastaurin. Our study identifies enzastaurin as a new, context dependent member of a heterogeneous group of anticancer compounds that induce “mitotic catastrophe," that is mitotic dysfunction accompanied by cell death. These data provide novel insight into the mechanism of action of enzastaurin and may allow the identification of biomarkers useful to identify CRC patients particularly likely, or not, to benefit from treatment with enzastaurin.