DNA sequence and analysis of human chromosome 9

Chromosome 9 is highly structurally polymorphic. It contains the largest autosomal block of heterochromatin, which is heteromorphic in 6-8% of humans, whereas pericentric inversions occur in more than 1% of the population. The finished euchromatic sequence of chromosome 9 comprises 109,044,351 base pairs and represents >99.6% of the region. Analysis of the sequence reveals many intra- and interchromosomal duplications, including segmental duplications adjacent to both the centromere and the large heterochromatic block. We have annotated 1,149 genes, including genes implicated in male-to-female sex reversal, cancer and neurodegenerative disease, and 426 pseudogenes. The chromosome contains the largest interferon gene cluster in the human genome. There is also a region of exceptionally high gene and G + C content including genes paralogous to those in the major histocompatibility complex. We have also detected recently duplicated genes that exhibit different rates of sequence divergence, presumably reflecting natural selection.     

Stratigraphic,chronological and behavioural contexts of Pleistocene Homo sapiens from Middle Awash,Ethiopia

Clarifying the geographic, environmental and behavioural contexts in which the emergence of anatomically modern Homo sapiens occurred has proved difficult, particularly because Africa lacked adequate geochronological, palaeontological and archaeological evidence. The discovery of anatomically modern Homo sapiens fossils at Herto, Ethiopia, changes this. Here we report on stratigraphically associated Late Middle Pleistocene artefacts and fossils from fluvial and lake margin sandstones of the Upper Herto Member of the Bouri Formation, Middle Awash, Afar Rift, Ethiopia. The fossils and artefacts are dated between 160,000 and 154,000 years ago by precise age determinations using the 40Ar/39Ar method. The archaeological assemblages contain elements of both Acheulean and Middle Stone Age technocomplexes. Associated faunal remains indicate repeated, systematic butchery of hippopotamus carcasses. Contemporary adult and juvenile Homo sapiens fossil crania manifest bone modifications indicative of deliberate mortuary practices.     

Receptive fields in the body-surface map in adult cortex defined by temporally correlated inputs

Receptive fields (RFs) obtained at specific cortical sites can be used to define a topographic map of the body surface in adult mammalian somatosensory cortex. This map is not static, and RFs at particular cortical sites can change in size and location throughout adult life. Conversely, the cortical loci at which a given skin surface is represented can shift hundreds of micrometres across the cortex in the koniocortical field, area 3b (refs 1-12). This plasticity suggests that RFs derive not from rigid anatomical connections, but by the selection of a subset of a large number of inputs. We have proposed that inputs are selected on the basis of temporal correlation 11-15. Here we test this idea by altering the correlation of inputs from two adjacent digits on the adult owl monkey hand by surgically connecting the skin surfaces of the two fingers (the formation of syndactyly). This manipulation increases the correlation of inputs from skin surfaces of adjacent fingers. The striking discontinuity between the zones of representation of adjacent digits on the somatosensory cortex disappeared. These results support the hypothesis that the topography of the body-surface map in the adult cortex is influenced by the temporal correlations of afferent inputs.     

Hyperthermic effect of disodium edetate injected into the lateral cerebral ventricle of the unanesthetized cat

Résumé La chélation des ions de calcium par l'EDTA Na₂ injecté dans le ventricule cérébral des chats non anesthésiés a produit une réaction hyperthermique caractérisée par une installation rapide et une durée brève. Cette réaction peut être bloquée par l'anesthésie au pentobarbital, mais non pas par les antipyrétiques, le N-acétyl-paraaminophénol ou le salicylate de sodium. Les résultats indiquent une action plus tardive dans la chaîne des événements que celle des pyrogènes.     

Inhibition of RNA-polymerase by arginine-rich histone fractions

Zusammenfassung Die Hemmung der RNS-Polymerase durch Histone ist eine direkte Folge der Präzipitierung der DNS aus der Lösung.