Plenary Conference

ANTARCTIC PENGUINS AS A SOURCE OF NEW PHYSIOLOGICAL CONCEPTS AND BIOMEDICAL INNOVATION Yvon LE MAHO Institut Pluridisciplinaire Hubert Curien, CNRS & Université de Strasbourg. 23 rue Becquerel 67087 Strasbourg. Antarctic penguins have been shown over the years to be quite a remarkable model for mechanisms of general interest. One of the most intriguing of these is the ability of a 40 kg emperor penguin to endure a fast lasting for as much as 120 days, compared to the about 40 days of fasting a 70 kg human is considered to be able to tolerate safely. Yet, we found that the major mechanism of adaptation to fasting, i.e. protein sparing, is similarly efficient in penguins and humans. The extremely long fast of emperor penguins is due to their social behavior of huddling together, which allows them to reduce their energetic expenditure below the basal metabolic rate without a drop in body temperature. This mechanism is not peculiar for penguins as it was then found to explain the rapid growth of newborn rabbits in their nest. But the spontaneous fast of penguins also allowed us to show that there is a mechanism which triggers their refeeding once a critical level has been reached in their body fuels. Yet, before this stage is reached, incubating penguins are able to preserve food in their stomach, which we have partly explained by the secretion of a small peptide, a β-defensin which we called spheniscin. The synthetized molecule was found to be remarkably efficient against Staphylococcus aureus and Aspergillus fumigatus.