Protein synthesis during the three phaservation in the rat.

National audienc

Domain Wall Creation in Nanostructures Driven by a Spin-Polarized Current

International audienceWe report on current-driven magnetization reversal in nanopillars with elements having perpendicular magnetic anisotropy. Whereas only the two uniform magnetization states are available under the action of a magnetic field, we observed current-induced Bloch domain walls in pillars as small as 50 100 nm 2. This domain wall state can be further controlled by current to restore the uniform states. The ability to nucleate and manipulate domain walls by a current gives insight into the reversal mechanisms of small nanoelements and provides new prospects for ultrahigh density spintronic devices

Life hung by a thread: endurance of Antarctic fauna in glacial periods

Today, Antarctica exhibits some of the harshest environmental conditions for life on Earth. During the last glacial period, Antarctic terrestrial and marine life was challenged by even more extreme environmental conditions. During the present interglacial period, polar life in the Southern Ocean is sustained mainly by large-scale primary production. We argue that during the last glacial period, faunal populations in the Antarctic were limited to very few areas of local marine productivity (polynyas), because complete, multiannual sea-ice and ice shelf coverage shut down most of the Southern Ocean productivity within today’s seasonal sea-ice zone. Both marine sediments containing significant numbers of planktonic and benthic foraminifera and fossil bird stomach oil deposits in the adjacent Antarctic hinterland provide indirect evidence for the existence of polynyas during the last glacial period. We advocate that the existence of productive oases in the form of polynyas during glacial periods was essential for the survival of marine and most higher-trophic terrestrial fauna. Reduced to such refuges, much of today’s life in the high Antarctic realm might have hung by a thread during the last glacial period, because limited resources available to the food web restricted the abundance and productivity of both Antarctic terrestrial and marine life.<br/

Analysis of the sequence variations in the Mhc DRB1-like gene of the endangered Humboldt penguin (Spheniscus humboldti)

The Major Histocompatibility Complex (Mhc) genomic region of many vertebrates is known to contain at least one highly polymorphic class II gene that is homologous in sequence to one or other of the human Mhc DRB1 class II genes. The diversity of the avian Mhc class II gene sequences have been extensively studied in chickens, quails, and some songbirds, but have been largely ignored in the oceanic birds, including the flightless penguins. We have previously reported that several penguin species have a high degree of polymorphism on exon 2 of the Mhc class II DRB1-like gene. In this study, we present for the first time the complete nucleotide sequences of exon 2, intron 2, and exon 3 of the DRB1-like gene of 20 Humboldt penguins, a species that is presently vulnerable to the dangers of extinction. The Humboldt DRB1-like nucleotide and amino acid sequences reveal at least eight unique alleles. Phylogenetic analysis of all the available avian DRB-like sequences showed that, of five penguin species and nine other bird species, the sequences of the Humboldt penguins grouped most closely to the Little penguin and the mallard, respectively. The present analysis confirms that the sequence variations of the Mhc class II gene, DRB1, are useful for discriminating among individuals within the same penguin population as well those within different penguin population groups and species

Adaptation-adaptabilité : comprendre la réponse adaptative avec pour objectif de la prédire

International audienc

Long-term effects of repeated handling and bleeding in wild caught Great Tits Parus major

Handling and bleeding are frequently used procedures in avian research and several studies show that they can exert short-term effects, such as elevation in corticosterone levels. However, the long-term effects of exposure to such manipulations are largely unknown, but could have important implications, especially for much of the long-term research on birds and experiments that involve longitudinal assessments. In this study, we evaluated the effect of handling and bleeding on some physiological and behavioural parameters. Hand-reared Great Tits Parus major originating from wild nests were used in two different experiments for other purposes. In these experiments, the birds were exposed to different frequencies of bleeding and handling events across a period of 45 days. The “high stress” group experienced a total of seven times handling and five times bleeding, while a “low stress” group was handled three times and bled only once. Thirty days after the experiments, when caught and handled from a cage, individuals of the high stress group were easier to catch, displayed significantly higher breath rates, and were more docile than individuals of the low stress group. No differences in body mass were detected. These results indicate that repeated manipulations cause evident long-term changes in coping with such procedures, which are likely due to learning effects, and provide empirical evidence that the past experimental history of an animal has to be taken into account in subsequent experiments.

Trans-species polymorphism of the Mhc class II DRB-like gene in banded penguins (genus Spheniscus)

Kikkawa EF , Tsuda TT, Sumiyama D, Naruse TK, Fukuda M, Kurita M, Wilson RP, LeMaho Y, Miller GD, Tsuda M, Murata K, Kulski JK, Inoko H . (2009). Trans-species polymorphism of the Mhc class II DRB-like gene in banded penguins (genus Spheniscus). Immunogenetics 61; 341-352