|
|
Van Petegem, F.,; Collins, T.,; Meuwis, M.-A.,; Gerday, C.,; Feller, G.,; Van Beeumen, J.,. (2002). Crystallization and preliminary X-ray analysis of a xylanase from the psychrophile Pseudoalteromonas haloplanktis. Acta Crystallogr. D Biol. Crystallogr., 58(9), 1494–1496.
Abstract: The 46 kDa xylanase from the Antarctic microorganism Pseudoalteromonas haloplanktis is an enzyme that efficiently catalyzes reactions at low temperatures. Here, the crystallization of both the native protein and the SeMet-substituted enzyme and data collection from both crystals using synchrotron radiation are described. The native data showed that the crystals diffract to 1.3 A resolution and belong to space group P212121, with unit-cell parameters a = 50.87, b = 90.51, c = 97.23 A. SAD data collected at the peak of the selenium absorption edge proved to be sufficient to determine the heavy-atom configuration and to obtain electron density of good quality.
Keywords: psychrophiles; cold-adapted enzyme; glycosyl hydrolases
Programme: 193
|
|
|
|
. (2011). Hormones and Behavior, 60(4), 362–370.
Abstract: Breeding individuals enter an emergency life-history stage when their body reserves reach a minimum threshold. Consequently, they redirect current activity toward survival, leading to egg abandonment in birds. Corticosterone (CORT) is known to promote this stage. How and to what extent CORT triggers egg abandonment when breeding is associated with prolonged fasting, however, requires further investigation.
Keywords: Prolactin, Breeding success, Glucocorticoid, Parental care, Long-term fasting,
Programme: 137
|
|
|
|
Jaeger A, Connan M, Richard P, Cherel Y, . (2010). Use of stable isotopes to quantify seasonal changes of trophic niche and levels of population and individual specialisation in seabirds
. Mar. Ecol. Prog. Ser., 401, 269–277.
Abstract: Niche variation is a widespread phenomenon that has important implications for ecological interactions and conservation biology, but few studies have quantified the trophic niche width (TNW) and its within- and between-individual components. We used stable isotopes of body feathers to investigate (1) seasonal isotopic niche changes of 4 southern procellariiforms and, (2) the level to which individuals are specialised relative to their population within each season. (1) δ13C and δ15N values of chicks and adults indicated a well-defined trophic segregation within the seabird assemblage during both the breeding and poorly known moulting (inter-nesting) periods, and they underlined marked species-specific seasonal changes. One species (light-mantled sooty albatross) remained within the Southern Ocean both during breeding and body feather moult, while the 3 others migrated either to oceanic subtropical waters (wandering and sooty albatrosses) or high isotopic marine areas (e.g. productive neritic waters; white-chinned petrel) during the moulting period. (2) Isotopic variances and TNW were generally low, indicating that birds belong to isotopic specialist populations within a given period. Variances and TNW were larger for white-chinned petrel chicks and light-mantled sooty albatross adults, respectively, indicating isotopic generalist populations and revealing 2 new foraging behaviours. Individual white-chinned petrel chicks segregated by their feather isotopic signatures, thus indicating individual/pair specialisation of parent birds during the chick-rearing period. The light-mantled sooty albatross population included mostly isotopic generalist individuals during the moulting period, with individuals using different habitats and diets. The study highlights the utility of feather isotopic signature for determining TNW and points out the necessity to develop such new approaches to better depict niche variations at both population and individual levels.
Programme: 109
|
|
|
|
Wang Hao, Nagy John D, Gilg Olivier, Kuang Yang, . (2009). The roles of predator maturation delay and functional response in determining the periodicity of predatorprey cycles
. Mathematical Biosciences, 221(1), 1–10.
Abstract: Population cycles in small mammals have attracted the attention of several generations of theoretical and experimental biologists and continue to generate controversy. Top-down and bottom-up trophic regulations are two recent competing hypotheses. The principal purpose of this paper is to explore the relative contributions of a variety of ecological factors to predatorprey population cycles. Here we suggest that for some species collared lemmings, snowshoe hares and moose in particular maturation delay of predators and the functional response of predation appear to be the primary determinants. Our study suggests that maturation delay alone almost completely determines the cycle period, whereas the functional response greatly affects its amplitude and even its existence. These results are obtained from sensitivity analysis of all parameters in a mathematical model of the lemmingstoat delayed system, which is an extension of Gilgs model. Our result may also explain why lemmings have a 4-year cycle whereas snowshoe hares have a 10-year cycle. Our parameterized model supports and extends Mays assertion that time delay impacts cycle period and amplitude. Furthermore, if maturation periods of predators are too short or too long, or the functional response resembles Holling Type I, then population cycles do not appear; however, suitable intermediate predator maturation periods and suitable functional responses can generate population cycles for both prey and predators. These results seem to explain why some populations are cyclic whereas others are not. Finally, we find parameterizations of our model that generate a 38-year population cycle consistent with the putative cycles of the moosewolf interactions on Isle Royale, Michigan.
Keywords: Population cycle, Snowshoe harelynx, Lemmingstoat, Moosewolf, Predatorprey, Delay differential equation,
Programme: 1036
|
|
|
|
Barthelemy M, Lystrup M B, Menager H, Miller S, Lilensten J,. (2011). First detection of polarization in jovian auroral H+3 emissions. A&A, 530.
Keywords: polarization / molecular data / planets and satellites: aurorae / planets and satellites: individual: Jupiter
Programme: 1026
|
|
|
|
. (2020). On the nightglow polarisation for space weather exploration (Vol. 10).
Abstract: We present here observations of the polarisation of four auroral lines in the auroral oval and in the polar cusp using a new ground polarimeter called Petit Cru. Our results confirm the already known polarisation of the red line, and show for the first time that the three other lines observed here (namely 557.7 nm, 391.4 nm and 427.8 nm) are polarised as well up to a few percent. We show that in several circumstances, this polarisation is linked to the local magnetic activity and to the state of the ionosphere through the electron density measured with EISCAT. However, we also show that the contribution of light pollution from nearby cities via scattering can not be ignored and can play an important role in polarisation measurements. This series of observations questions the geophysical origin of the polarisation. It also leaves open its relation to the magnetic field orientation and to the state of both the upper atmosphere and the troposphere.
Keywords: polarisation / aurora
Programme: 1026
|
|
|
|
Post Alexandra L, Beaman Robin J, O'Brien Philip E, Elaume Marc, Riddle Martin J, . (2011). Community structure and benthic habitats across the George V Shelf, East Antarctica: Trends through space and time
. Deep Sea Res. Part II Top. Stud. Oceanogr., 58(1-2), 105–118.
Keywords: Polar waters, Adlie Land, Physical surrogates, Benthos, Benthic environment, Iceberg scouring,
Programme: 1124
|
|
|
|
GENTHON C. , MAGAND O. , KRINNER G. , FILY M. (2009). Do climate models underestimate snow accumulation on the Antarctic plateau? A re-evaluation of/from in situ observations in East Wilkes and Victoria Lands. Annals of glaciology, 50, 61–65.
Abstract: It has been suggested that meteorological and climate models underestimate snow accumulation on the Antarctic plateau, because accumulation (or surface mass balance (SMB)) is dominated by clear-sky precipitation while this process is not properly taken into account in the models. Here, we show that differences between model and field SMB data are much reduced when the in situ SMB reports used to evaluate the models are filtered through quality-control criteria and less reliable reports are subsequently left out. We thus argue that, although not necessarily unsupported, model biases and their interpretations in terms of clear-sky vs synoptic precipitation on the Antarctic plateau may have been overstated in the past. To avoid such misleading issues, it is important that in situ SMB reports of insufficient or unassessed reliability are discarded, even at the cost of a strong reduction in spatial sampling and coverage.
Keywords: polar regions ; Antarctica ; Diamond dust ; Victoria Land ; Wilkes Land ; ground truth ; Observation data ; algorithm performance ; Climate models ; accumulation ; Clear sky ; atmospheric precipitation ; mass balance ; Glacier balance ; ice sheets ; Polar region
Programme: 411;454
|
|
|
|
David C, Haefele A, Keckhut P, Marchand M, Jumelet J, Leblanc T, Cenac C, Laqui C, Porteneuve J, Haeffelin M, Courcoux Y, Snels M, Viterbini M, Quatrevalet M, . (2012). Evaluation of stratospheric ozone, temperature, and aerosol profiles from the LOANA lidar in Antarctica
. Polar Biol., 6, 209–225.
Keywords: Polar ozone, Polar stratospheric clouds, Lidar, Stratosphere,
Programme: 1124
|
|
|
|
David C, Haefele A, Keckhut P, Marchand M, Jumelet J, Leblanc T, Cenac C, Laqui C, Porteneuve J, Haeffelin M, Courcoux Y, Snels M, Viterbini M, Quatrevalet M, . (2012). Evaluation of stratospheric ozone, temperature, and aerosol profiles from the LOANA lidar in Antarctica
. Polar Science, 6(34), 209–225.
Keywords: Polar ozone, Polar stratospheric clouds, Lidar, Stratosphere,
Programme: 209
|
|
