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. (2008). A Review of Antarctic Surface Snow Isotopic Composition: Observations, Atmospheric Circulation, and Isotopic Modeling*. Journal of climate, 21(13), 3359–3387.
Keywords: Snow; Antarctica; Atmospheric circulation; Isotopic analysis; In situ observations
Programme: 355;454
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Krinner, G.; Guicherd, B.; Ox, K.; Genthon, C.; Magand, O. (2008). Influence of Oceanic Boundary Conditions in Simulations of Antarctic Climate and Surface Mass Balance Change during the Coming Century. Journal of climate, 21(5), 938–962.
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. (1996). Journal of Applied Meteorology, 35(7), 1142–1152.
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Geoffroy, L.; Aubourg, C.; Callot, J.-P.; Barrat, J.-A. (2007). Mechanisms of crustal growth in large igneous provinces: The north Atlantic province as a case study. Geological Society of America Special Papers, 430, 747–774.
Abstract: The mechanisms of magma crust accretion at large igneous provinces (LIPs) are questioned using arguments based on the north Atlantic case. Published and new data on the calculated flow vectors within dike swarms feeding the early traps and subsequent seaward-dipping reflector lavas suggest that most of the mafic magmas forming the north Atlantic LIP transited through a small number of igneous centers. The magma was injected centrifugally in dike swarms at some distance away from individual igneous centers along the trend of the maximum horizontal stress acting in the crust, feeding lava piles via dikes intersecting the ground surface. This mechanism is similar to that observed in present-day Iceland and, more generally, in mafic volcano-tectonic systems. The absence of generalized vertical magma transit in a LIP has major geodynamic consequences. We cannot link the surface extent of LIP magmas to the dimensions of the mantle melting zone as proposed in former plume head models. The distribution of LIP magmas at the surface is primarily controlled by the regional stress field acting within the upper crust, but is also affected by magma viscosity. The igneous centers feeding LIPs most likely represent the crustal expression of small-scale convective cells of the buoyant mantle naturally located beneath the mechanical lithosphere.
Keywords: traps; volcanic margin; dike swarm; small-scale convection; AMS
Programme: 290
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Marx J.C., Poncin J., Simorre J.P., Ramteke P.W. & Feller, G. (2008). The non-catalytic triad of alpha-amylases: a novel structural motif involved in conformational stability. Proteins: Structure, Function, and Bioinformatics, 70(2). Retrieved July 1, 2024, from http://dx.doi.org/10.1002/prot.21594
Abstract: Chloride-activated alpha-amylases contain a noncatalytic triad, independent of the glycosidic active site, perfectly mimicking the catalytic triad of serine-proteases and of other active serine hydrolytic enzymes. Mutagenesis of Glu, His, and Ser residues in various alpha-amylases shows that this pattern is a structural determinant of the enzyme conformation that cannot be altered without losing the intrinsic stability of the protein. 1H-15N NMR spectra of a bacterial alpha-amylase reveal proton signals that are identical with the NMR signature of catalytic triads and especially a deshielded proton involving a protonated histidine and displaying properties similar to that of a low barrier hydrogen bond. It is proposed that the H-bond between His and Glu of the noncatalytic triad is an unusually strong interaction, responsible for the observed NMR signal and for the weak stability of the triad mutants. Furthermore, a stringent template-based search of the Protein Data Bank demonstrated that this motif is not restricted to alpha-amylases, but is also found in 80 structures from 33 different proteins, amongst which SH2 domain-containing proteins are the best representatives.
Programme: 193
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Touaty M. (1999). Doctoral thesis, , .
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Pisano E., Ozouf Costaz C. & Prirodina V.P. (1998). Chromosome diversification in Antarctic fish (Notothenioidei)..
Abstract: Fishes of Antarctica. A biologival overview. springer Verlag, Italia
Programme: 281
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Petkov, B.; Vitale, V.; Tomasi, C.; Bonaf, U.; Scaglione, S.; Flori, D.; Santaguida, R.; Gausa, M.; Hansen, G.; Colombo, T. (2006). Narrowband filter radiometer for ground-based measurements of global ultraviolet solar irradiance and total ozone. Applied optics, 45(18), 4383–4395.
Keywords: Atmospheric optics; Ozone; Instrumentation, measurement, and metrology
Programme: 1176
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Raccurt, M.; Baudimont, F.; Tirard, J.; Rey, B.; Moureaux, E.; Geloen, A.; Duchamp, C. (2008). Growing in Antarctica, a challenge for white adipose tissue development in Adelie penguin chicks (Pygoscelis adeliae). Am. J. Physiol. Regul. Integr. Comp. Physiol., 295(5), R1671–1679.
Abstract: Rapid growth is of crucial importance for Adelie penguin chicks reared during the short Antarctic summer. It partly depends on the rapid ontogenesis of fat stores that are virtually null at hatching but then develop considerably (x40) within a month to constitute both an isolative layer against cold and an energy store to fuel thermogenic and growth processes. The present study was aimed at identifying by RT-PCR the major transcriptional events that chronologically underlie the morphological transformation of adipocyte precursors into mature adipocytes from hatching to 30 days of age. The peak expression of GATA binding protein 3, a marker of preadipocytes, at day 7 posthatch indicates a key proliferation step, possibly in relation to the expression of C/EBP{alpha} (C/EBP{alpha}). High plasma total 3,5,3'-triiodo-L-thyronine (T3) levels and high levels of growth hormone receptor transcripts at hatching suggested that growth hormone and T3 play early activating roles to favor proliferation of preadipocyte precursors. Differentiation and growth of preadipocytes may occur around day 15 in connection with increased abundance of transcripts encoding IGF-1, proliferator-activated receptor-{gamma}, and C/EBP{beta}, gradually leading to functional maturation of metabolic features of adipocytes including lipid uptake and storage (lipoprotein lipase, fatty-acid synthase) and late endocrine functions (adiponectin) by day 30. Present results show a close correlation between adipose tissue development and chick biology and a difference in the scheduled expression of regulatory factors controlling adipogenesis compared with in vitro studies using cell lines emphasizing the importance of in vivo approaches.
Programme: 131
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Rey, B.; Halsey, L.G.; Dolmazon, V.; Rouanet, J.-L.; Roussel, D.; Handrich, Y.; Butler, P.J.; Duchamp, C. (2008). Long-term fasting decreases mitochondrial avian UCP-mediated oxygen consumption in hypometabolic king penguins. Am J Physiol Regul Integr Comp Physiol, 295(1), R92–100.
Abstract: In endotherms, regulation of the degree of mitochondrial coupling affects cell metabolic efficiency. Thus it may be a key contributor to minimizing metabolic rate during long periods of fasting. The aim of the present study was to investigate whether variation in mitochondrial avian uncoupling proteins (avUCP), as putative regulators of mitochondrial oxidative phosphorylation, may contribute to the ability of king penguins (Aptenodytes patagonicus) to withstand fasting for several weeks. After 20 days of fasting, king penguins showed a reduced rate of whole animal oxygen consumption ([IMG]f1.gif“ ALT=”V“ BORDER=”0“>O2; -33%) at rest, together with a reduced abundance of avUCP and peroxisome proliferator-activated receptor-{gamma} coactivator-1{alpha} (PGC1-{alpha}) mRNA in pectoralis muscle (-54%, -36%, respectively). These parameters were restored after the birds had been refed for 3 days. Furthermore, in recently fed, but not in fasted penguins, isolated muscle mitochondria showed a guanosine diphosphate-inhibited, fatty acid plus superoxide-activated respiration, indicating the presence of a functional UCP. It was calculated that variation in mitochondrial UCP-dependent respiration in vitro may contribute to nearly 20% of the difference in resting [IMG]f1.gif” ALT=“V” BORDER=“0”>O2 between fed or refed penguins and fasted penguins measured in vivo. These results suggest that the lowering of avUCP activity during periods of long-term energetic restriction may contribute to the reduction in metabolic rate and hence the ability of king penguins to face prolonged periods of fasting.
Programme: 131;394
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