Late Quaternary sedimentation off the western Sahara

Late Quaternary sediments on the West African continental margin between 24°N and 15°N were studied with RV METEOR (1971) and VALDIVIA (1975). Cores on the shelf were taken with a 6-m-vibrocorer, in deeper water mainly with a 12 m Kastenlot corer. During Holocene, and up to the present time, more or less and climatic conditions north of the Senegal River area reduced terrigenous supply. Therefore, the biogenic-carbonate content exceeds about 50%. Wüstenquarz numbers (red + yellow quartz : white quartz x 100) are high (20 to mmore than 200), indicating eolian input. The Senegal River supplied fine grained, green colored, terrigenous material with some plant debris. During Würm, the Mediterranean climatic zone with winter rains was shifted more than 5° to the South and was reaching Banc d'Arguin (at about 20°N). Therefore, the terrigenous supply was increased in this northern part and consequently the carbonate content and the Wüstenquartz numbers dropped below 50% and 10, respectively. The arid zone was also shifted to the south; as a consequence, the Senegal River did not reach the sea, eolian supply diluted the biogenic carbonates, and increased Wüstenquartz numbers to more than 200. Eolian dunes covered parts of the shelf. Ratios of radiolarians/plankonic foraminifera and planktonic/benthonic organisms and sedimentation rates of organic carbon indicate stronger upwelling in the northern region. Turbidity currents were more frequent, eroding as much as a third of the material supplied ba pelagic sedimentation

A New Human Somatic Stem Cell from Placental Cord Blood with Intrinsic Pluripotent Differentiation Potential

Here a new, intrinsically pluripotent, CD45-negative population from human cord blood, termed unrestricted somatic stem cells (USSCs) is described. This rare population grows adherently and can be expanded to 1015 cells without losing pluripotency. In vitro USSCs showed homogeneous differentiation into osteoblasts, chondroblasts, adipocytes, and hematopoietic and neural cells including astrocytes and neurons that express neurofilament, sodium channel protein, and various neurotransmitter phenotypes. Stereotactic implantation of USSCs into intact adult rat brain revealed that human Tau-positive cells persisted for up to 3 mo and showed migratory activity and a typical neuron-like morphology. In vivo differentiation of USSCs along mesodermal and endodermal pathways was demonstrated in animal models. Bony reconstitution was observed after transplantation of USSC-loaded calcium phosphate cylinders in nude rat femurs. Chondrogenesis occurred after transplanting cell-loaded gelfoam sponges into nude mice. Transplantation of USSCs in a noninjury model, the preimmune fetal sheep, resulted in up to 5% human hematopoietic engraftment. More than 20% albumin-producing human parenchymal hepatic cells with absence of cell fusion and substantial numbers of human cardiomyocytes in both atria and ventricles of the sheep heart were detected many months after USSC transplantation. No tumor formation was observed in any of these animals