Holocene Southern Ocean surface temperature variability west of the Antarctic Peninsula

The disintegration of ice shelves, reduced sea-ice and glacier extent, and shifting ecological zones observed around Antarctica highlight the impact of recent atmospheric and oceanic warming on the cryosphere. Observations and models suggest that oceanic and atmospheric temperature variations at Antarctica's margins affect global cryosphere stability, ocean circulation, sea levels and carbon cycling. In particular, recent climate changes on the Antarctic Peninsula have been dramatic, yet the Holocene climate variability of this region is largely unknown, limiting our ability to evaluate ongoing changes within the context of historical variability and underlying forcing mechanisms. Here we show that surface ocean temperatures at the continental margin of the western Antarctic Peninsula cooled by 3-4 °C over the past 12,000 years, tracking the Holocene decline of local (65° S) spring insolation. Our results, based on TEX(86) sea surface temperature (SST) proxy evidence from a marine sediment core, indicate the importance of regional summer duration as a driver of Antarctic seasonal sea-ice fluctuations. On millennial timescales, abrupt SST fluctuations of 2-4 °C coincide with globally recognized climate variability. Similarities between our SSTs, Southern Hemisphere westerly wind reconstructions and El Ni?o/Southern Oscillation variability indicate that present climate teleconnections between the tropical Pacific Ocean and the western Antarctic Peninsula strengthened late in the Holocene epoch. We conclude that during the Holocene, Southern Ocean temperatures at the western Antarctic Peninsula margin were tied to changes in the position of the westerlies, which have a critical role in global carbon cycling.     

A Systems Approach for Engaging Groups in Global Complexity: Capacity Building Through an Online Course

Sustainability is not simply about changing practices but more centrally about agreeing to change practices together. To achieve such an end, groups need to improve processes for making complex decisions together. An online course was designed and tested linking students in the United States and in Australia. Students engaged in a re-enactment of deliberations based on Hasan Ozbekhan’s “Predicament of Mankind,” which was constructed originally under assignment from the founders of the Club of Rome in 1970. This re-enactment included contemporary research for examples of a set of 49 continuous critical problems of mankind, asynchronous clarification of these problems using a wiki, pair-wise construction of a systems view of problems assessed to be of highest priority by the class, narrative analysis of the structure, and creative suggestions for resolving the systems problem based on resources available today. This report comments on the strengths and challenges identified in an initial application of an approach for building collaborative and systems thinking skills through an online course in a general education curriculum. Findings are particularly meaningful for contemporary policy makers as well as online educators.     

Inhibitory effects of LHRH on LH receptors in the rat testis]

A single injection of LHRH to the adult male rat, as of its analog [D-Ala6, des-Gly-NH102] LHRH ethylamide, resulted in a marked decrease in LH receptors in the tests. Plasma testosterone level and the weight of the seminal vesicles and prostate were also decreased after treatment. These data demonstrate that LHRH can decrease the sensitivity of LH receptors and testicular function in the rat.     

The effects of age and nutritional state on m.e.p.p. amplitude

Summary A quantitative restriction of food intake for 7 days reduced the amplitude of spontaneous miniature endplate potentials by about 1/3 in rats aged 30 days but not in rats aged 110 days.I would like to thank Dr D. V. Roberts for encouragement and advice and the Medical Research Council and the Muscular Dystrophy Group of Great Britain for financial support.     

Location of MHC-encoded transporters in the endoplasmic reticulum and cis-Golgi.

Immune recognition of intracellular proteins is mediated by major histocompatibility complex (MHC) class I molecules that present short peptides to cytotoxic T cells. Evidence suggests that peptides arise by cleavage of proteins in the cytoplasm and are transported by a signal-independent mechanism into a pre-Golgi region of the cell, where they take part in the assembly of class I heavy chains with beta 2-microglobulin (reviewed in refs 5-7). Analysis of cells that have defects in class I molecule assembly and antigen presentation has shown that this phenotype can result from mutations in either of the two ABC transporter genes located in the class II region of the MHC. This suggested that the protein complex encoded by these two genes transports peptides from the cytosol into the endoplasmic reticulum. Here we report additional evidence by showing that the transporter complex is located in the endoplasmic reticulum membrane and is probably oriented with its ATP-binding domains in the cytosol.     

1-methyl-4-phenylpyridine is neurotoxic to the nigrostriatal dopamine pathway

Systemic administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is neurotoxic to cerebral dopaminergic neurones in several animal species, and can cause parkinsonism in man. The mechanism of this action may be indirect. MPTP is oxidized in the brain to a pyridinium species, 1-methyl-4-phenylpyridine (MPP+)6. This oxidation is greatly decreased by inhibition of monoamine oxidase B6, as are the biochemical effects of MPTP in the mouse and its neurotoxicity in the monkey. We now show that MPP+ exerts a powerful neurotoxic action on the nigrostriatal dopamine system of the rodent.