The diet of Australopithecus sediba

Specimens of Australopithecus sediba from the site of Malapa, South Africa (dating from approximately 2 million years (Myr) ago) present a mix of primitive and derived traits that align the taxon with other Australopithecus species and with early Homo. Although much of the available cranial and postcranial material of Au. sediba has been described, its feeding ecology has not been investigated. Here we present results from the first extraction of plant phytoliths from dental calculus of an early hominin. We also consider stable carbon isotope and dental microwear texture data for Au. sediba in light of new palaeoenvironmental evidence. The two individuals examined consumed an almost exclusive C(3) diet that probably included harder foods, and both dicotyledons (for example, tree leaves, fruits, wood and bark) and monocotyledons (for example, grasses and sedges). Like Ardipithecus ramidus (approximately 4.4 Myr ago) and modern savanna chimpanzees, Au. sediba consumed C(3) foods in preference to widely available C(4) resources. The inferred consumption of C(3) monocotyledons, and wood or bark, increases the known variety of early hominin foods. The overall dietary pattern of these two individuals contrasts with available data for other hominins in the region and elsewhere.     

Cell contact- and shape-dependent regulation of vinculin synthesis in cultured fibroblasts

Recent studies have demonstrated the fundamental role of cell-substrate contacts and changes in cell shape in the regulation of cell growth, motility and differentiation, but the molecular basis for these phenomena is poorly understood. Because of the involvement of cytoskeletal networks in cell morphogenesis and contact formation, it is of interest that the expression of genes encoding several cytoskeletal proteins is markedly affected by changes in cell contacts and configuration. Because most of these phenomena involve changes in the form, extent or topology of cell contacts, we sought to determine whether the expression of components directly involved in the formation of cell-cell or cell-substrate contacts is affected by the respective cellular interactions. A suitable candidate for such analysis is vinculin, a cytoskeletal protein of relative molecular mass (Mr) 130,000 (130K), which is localized in focal contacts and intercellular adherens junctions. The assembly of vinculin into a membrane-bound junctional plaque seems to be one of the earliest cellular responses to contact with exogenous substrates, leading to the subsequent local assembly of the actin-rich microfilament bundles. Here we report on the regulation of vinculin synthesis in response to environmental conditions that affect cell shape and contacts.     

Dental microwear texture analysis shows within-species diet variability in fossil hominins

Reconstructing the diets of extinct hominins is essential to understanding the paleobiology and evolutionary history of our lineage. Dental microwear, the study of microscopic tooth-wear resulting from use, provides direct evidence of what an individual ate in the past. Unfortunately, established methods of studying microwear are plagued with low repeatability and high observer error. Here we apply an objective, repeatable approach for studying three-dimensional microwear surface texture to extinct South African hominins. Scanning confocal microscopy together with scale-sensitive fractal analysis are used to characterize the complexity and anisotropy of microwear. Results for living primates show that this approach can distinguish among diets characterized by different fracture properties. When applied to hominins, microwear texture analysis indicates that Australopithecus africanus microwear is more anisotropic, but also more variable in anisotropy than Paranthropus robustus. This latter species has more complex microwear textures, but is also more variable in complexity than A. africanus. This suggests that A. africanus ate more tough foods and P. robustus consumed more hard and brittle items, but that both had variable and overlapping diets.     

In vitro exploration of a circadian Rhythm in adrenocorticotropic activity of C mouse hypophysis

Zusammenfassung Ein circadianer Rhythmus in der adrenocorticotropen Wirkung der Hypophyse bei Inzucht-C-Mäusen wird durch einin vitro-Verfahren nachgewiesen. Es werden Angaben der Phasenunterschiede zwischen dem hypophysären Rhythmus und den gleichfalls circadian-periodischen Schwankungen gemacht: (1) im Serum-Corticosteron und (2) in der Reaktion der Nebenniere auf ACTH,in vitro.     

Evidence for chemical coding of color discrimination in goldfish brain

Résumé Des comportements provoqués par la discrimination de couleurs ont pu être observés chez des poissons ayant reçu par injection intracranienne des extraits de cerveau de poissons donneursentrainés. Cette expérience est utilisée comme essai biologique pour la purification et l'identification des substances actives.