Genetic history of an archaic hominin group from Denisova Cave in Siberia

Using DNA extracted from a finger bone found in Denisova Cave in southern Siberia, we have sequenced the genome of an archaic hominin to about 1.9-fold coverage. This individual is from a group that shares a common origin with Neanderthals. This population was not involved in the putative gene flow from Neanderthals into Eurasians; however, the data suggest that it contributed 4-6% of its genetic material to the genomes of present-day Melanesians. We designate this hominin population 'Denisovans' and suggest that it may have been widespread in Asia during the Late Pleistocene epoch. A tooth found in Denisova Cave carries a mitochondrial genome highly similar to that of the finger bone. This tooth shares no derived morphological features with Neanderthals or modern humans, further indicating that Denisovans have an evolutionary history distinct from Neanderthals and modern humans.     

Global landscape of protein complexes in the yeast Saccharomyces cerevisiae

Identification of protein-protein interactions often provides insight into protein function, and many cellular processes are performed by stable protein complexes. We used tandem affinity purification to process 4,562 different tagged proteins of the yeast Saccharomyces cerevisiae. Each preparation was analysed by both matrix-assisted laser desorption/ionization-time of flight mass spectrometry and liquid chromatography tandem mass spectrometry to increase coverage and accuracy. Machine learning was used to integrate the mass spectrometry scores and assign probabilities to the protein-protein interactions. Among 4,087 different proteins identified with high confidence by mass spectrometry from 2,357 successful purifications, our core data set (median precision of 0.69) comprises 7,123 protein-protein interactions involving 2,708 proteins. A Markov clustering algorithm organized these interactions into 547 protein complexes averaging 4.9 subunits per complex, about half of them absent from the MIPS database, as well as 429 additional interactions between pairs of complexes. The data (all of which are available online) will help future studies on individual proteins as well as functional genomics and systems biology.     

Benzodiazepine receptors resolved

To date, attempts to map the distribution and density of benzodiazepine receptors in the CNS have been dominated by radiohistochemical techniques with conventional receptor binding. Their limited resolution, however, prompted us to try an immunohistochemical approach. Purified GABA/benzodiazepine receptors, prepared from bovine cerebral cortex, have been used to raise monoclonal antibodies for this purpose. Immunoreactive sites in rat brain, spinal cord and retina as well as in bovine and post-mortem human brain were found to be concentrated on neuronal cell bodies and processes in those regions known to be innervated by GABAergic neurons. Electron microscopic analysis revealed a selective staining of axosomatic and axodendritic pre- and postsynaptic contacts.     

Oxygen uptake rhythms in a cockroach gauged by variance spectra

Zusammenfassung Der Sauerstoffverbrauch vonPeriplaneta americana (L.) wurde im Dauerlicht und im 24-stündigen Licht-Dunkelwechsel bei 30, 24 oder 18°C alle 20 min bestimmt. Im Varianzspektrum dieser Beobachtungsreihen lassen sich neben der ungefähren Tagesperiodik (Circadian-Periodik) auch höherfrequente, unregelmässigere und weniger prominente Rhythmen nachweisen.     

Pleistocene Homo sapiens from Middle Awash,Ethiopia

The origin of anatomically modern Homo sapiens and the fate of Neanderthals have been fundamental questions in human evolutionary studies for over a century. A key barrier to the resolution of these questions has been the lack of substantial and accurately dated African hominid fossils from between 100,000 and 300,000 years ago. Here we describe fossilized hominid crania from Herto, Middle Awash, Ethiopia, that fill this gap and provide crucial evidence on the location, timing and contextual circumstances of the emergence of Homo sapiens. Radioisotopically dated to between 160,000 and 154,000 years ago, these new fossils predate classic Neanderthals and lack their derived features. The Herto hominids are morphologically and chronologically intermediate between archaic African fossils and later anatomically modern Late Pleistocene humans. They therefore represent the probable immediate ancestors of anatomically modern humans. Their anatomy and antiquity constitute strong evidence of modern-human emergence in Africa.     

Oxidative stress on plasmid DNA induced by inhalable particles in the urban atmosphere

Plasmid DNA assay is a newly-developed in vitro method to investigate bioreactivity of particles. In this paper, this method was used to study the bioreactivity of PM10 (particulate matter with aerodynamic diameter of less than 10 μm) and PM2.5 (particulate matter with aerodynamic diameter of less than 2.5 μm). Samples and dust storm particles were collected in 2001 in an urban area, a satellite city and a clean air area in Beijing. A big difference was found for oxidative DNA stress induced by different particulate matter (PM) samples, with the TM50 (particle mass causing 50% damage to DNA) values varying by a factor over 10. This was closely dependent on the sizes of particles as well as the variation in relative proportion of mineral matter. PM2.5 samples generally impose larger oxidative stress on plasmid DNA than PM10 samples. Airborne particles collected during dust storm episodes, usually with a higher proportion of mineral matter, have a much lower oxidative capacity than those collected during non-dust storm episodes. PM samples and their water-soluble fractions usually have similar bioreactivities, demonstrating that oxidative capacity of Beijing airborne particles is mainly sourced from their water-soluble fractions.