Modulation of lipogenic enzymes, fatty acid synthase and Δ 9 -desaturase, in relation to migration in the western sandpiper ( Calidris mauri )

Abstract

Long-distance migration in birds is characterized physiologically by periods of rapid fattening and lipogenesis, and increased desaturation of fatty acids stored in adipose tissue. We investigated seasonal, age- and sex-related differences in activities of two lipogenic enzymes, fatty acid synthase and delta9-desaturase, in relation to migration in the small, Arctic-nesting western sandpiper (Calidris mauri). Migration, and associated lipogenesis and fattening, involved marked upregulation of these enzymes in this species. However, this increase in enzyme activity was only seen in actively migrating birds during spring migration, when fatty acid synthase and delta9-desaturase levels increased by 53% and 113%, respectively, compared to non-migrating birds. There was no change in fatty acid synthase enzyme activity during the premigration period, even though body mass of adult birds increased significantly during this period. Similarly, there was no increase in delta9-desaturase activity during premigration, despite the fact that birds increase the proportion of monounsaturated fatty acids in their fat stores at this time. We suggest that upregulation of lipogenic enzymes is required to support high rates of mass gain (0.4 g day(-1)) during short (1-4 day) periods at stop-over sites. However, slower rates of mass gain (0.09 g day(-1)) over several weeks prior to migration can be achieved without any increase in tissue-specific enzyme activity.

Annual life-stage regulation of lipid metabolism and storage and association with PPARs in the migrant species Gray Catbird (Dumetella carolinensis)

“…Elevated liver mass during pre-migration and autumn migration may be attributed to increased lipid accumulation or tissue hypertrophy. Lipogenesis, the synthesis of fatty acids from acetyl CoA in the liver, is carried out by several enzymes including malic enzyme and Δ 9 -desaturase -both of which show marked increases in activity during pre-migration (DeGraw, 1975;Shah et al, 1978;Egeler et al, 2000) and are PPAR targets (Yu et al, 2003;Wang et al, 2006). Increased lipogenesis can result in lipid accumulation in the liver, and lipid content is increased in the liver during the pre-migratory period in some species (Odum and Perkinson, 1951;King et al, 1963).…”

Preparing for Migration? The Effects of Photoperiod and Exercise on Muscle Oxidative Enzymes, Lipid Transporters, and Phospholipids in White‐Crowned Sparrows

“…These can include changes in nutrient stores, organ sizes, hematocrit, muscle and liver biochemistry, resistance to sleep deprivation, and endocrine function (George and Vallyathan 1964;Berthold 1975;Evans et al 1992;Piersma and Everaarts 1996;Breuner et al 1999;Egeler et al 2000;Guglielmo et al 2002a;Fusani and Gwinner 2004;Landys et al 2004b;McWilliams et al 2004;Rattenborg et al 2004). In the laboratory, a captive analog of migratory condition known as zugunruhe can be induced in birds by altering the photoperiod.…”

How to get fat: nutritional mechanisms of seasonal fat accumulation in migratory songbirds

“…Nevertheless, it should be mentioned that selective feeding on aphids, observed in several warbler species during migratory stopovers, is assumed to be related to the high sugar content of these insects (Bibby and Green 1981;Glutz von Blotzheim 1986). Moreover, seasonal modulations of hepatic lipogenic enzymes, such as malic enzyme and fatty acid synthase, as reported in several migrant species (Stevens 1996;Ramenofsky et al 1999;Egeler et al 2000), may point on to the use of carbohydrates for migratory fat accumulation in some species.…”