A probable effect of diabetes mellitus on incorporation of amino acids into proteins catalyzed by isolated rat liver nuclei

Résumé On a étudié l'incorporation des acides aminés radioactifs étiquettés dans des matériaux chauds, insolubles dans l'acidetri-chloroacétique (en marquant les protéines nucléaires), catalysés par des noyaux hépatiques éxtraits de rats normaux, de rats atteints de diabète causé par l'alloxane et de diabète traité à l'insuline. Dans plusieurs expériences, l'incorporation diminuée observée dans les noyaux provenant des rats diabétiques put être augmentée par l'insuline in vivo.     

Increased productivity in the subantarctic ocean during Heinrich events

Massive iceberg discharges from the Northern Hemisphere ice sheets, 'Heinrich events', coincided with the coldest periods of the last ice age. There is widespread evidence for Heinrich events and their profound impact on the climate and circulation of the North Atlantic Ocean, but their influence beyond that region remains uncertain. Here we use a combination of molecular fingerprints of algal productivity and radioisotope tracers of sedimentation to document eight periods of increased productivity in the subpolar Southern Ocean during the past 70,000 years that occurred within 1,000-2,000 years of a Northern Hemisphere Heinrich event. We discuss possible causes for such a link, including increased supply of iron from upwelling and increased stratification during the growing season, which imply an alteration of the global ocean circulation during Heinrich events. The mechanisms linking North Atlantic iceberg discharges with subantarctic productivity remain unclear at this point. We suggest that understanding how the Southern Ocean was altered during these extreme climate perturbations is critical to understanding the role of the ocean in climate change.     

Intercepting the first rat ashore

A single Norway rat released on to a rat-free island was not caught for more than four months, despite intensive efforts to trap it. The rat first explored the 9.5-hectare island and then swam 400 metres across open water to another rat-free island, evading capture for 18 weeks until an aggressive combination of detection and trapping methods were deployed simultaneously. The exceptional difficulty of this capture indicates that methods normally used to eradicate rats in dense populations are unlikely to be effective on small numbers, a finding that could have global implications for conservation on protected islands.