Abstract: King penguin chicks, that are strictly terrestrial during first year after hatching, must depart to sea to reach nutritional emancipation. Juvenile survival therefore depends on their adaptation to the energetic challenges of marine life: 1) harsh thermal environment, 2) long distant food resources, 3) repeated, deep and prolonged nutritional divings.
To elucidate these adaptations, the transcriptome of pectoralis muscle, the main thermogenic and locomotor tissue, was analysed in juveniles that had never been to sea (n=4) and in naturally adapted juveniles (n=3) by using chicken Affymetrix DNA chips (Profilexpert, Lyon).
Results showed the differential expression of nearly 3600 genes after marine life. Genes encoding enzymes of carbohydrate metabolism were down regulated while those encoding lipid transport and catabolism were up regulated suggesting an increased use of lipids as energy substrates. Further, transcripts encoding enzymes involved in cellular defense against reactive oxygen species and the associated injuries were also up regulated, suggesting an adaptive response against oxidative stress.
This study opens large perspectives to elucidate how king penguins can survive in an energetically unfavorable and pro-oxidative environment and what contributes to their remarkable longevity.
This study received the financial support of the French Polar Institut (IPEV).