Metabolic plasticity for subcutaneous fat accumulation in a long distance migratory bird traced by 2H2O

Abstract

The migrant black-tailed godwit (Limosa limosa) traditionally used natural wetlands in the Iberian Peninsula to prepare for migratory flights by feeding mainly in estuaries. In recent decades, this species has become increasingly dependent on rice fields, thereby relying on a plant-based diet for fuelling. Dietary fatty acids (FA) seem to be determinant to the composition of accumulated subcutaneous fat in migratory birds. It is still unclear whether metabolic plasticity allows for modification and/or synthesis of FA, contributing to a lipid profile that enables a successful migratory performance. Deuterated water was administered to captive black-tailed godwits submitted to two diets (fly larvae versus rice) and the incorporation of deuterium ( 2 H) into subcutaneous triglycerides was analyzed by NMR. A recently developed localized biopsy method for sampling subcutaneous fat was employed with later successful release of all birds into the wild. The average chemical structure reflected mostly a mixture of saturated and monounsaturated 16-and 18-carbon FA, a profile frequently found in migrant birds. Significantly higher levels of polyunsaturated FA, as well as detectable levels of n-3 FA, were observed in fly-larvae-fed birds. Excess 2 H-enrichments in FA revealed significantly higher rates of fractional de novo lipogenesis and FA desaturation capacity in rice-fed birds. This novel and nonlethal tracer method revealed the capacity of this species to alter its lipid metabolism to compensate for a poorer dietary lipid contribution. Because of its versatility, adapting this method to other scenarios and/or other migratory species is considered feasible and costeffective.

Dietary starch promotes hepatic lipogenesis in barramundi (Lates calcarifer)

“…NMR spectra of TAG and NEFA samples were obtained at 25°C with a Bruker Avance III HD system with an UltraShield Plus magnet (11•7 T, 2 H operating frequency 500 MHz) equipped with a 5-mm 2 H-selective probe with 19F lock and 1 H-decoupling coil. Lipids were reconstituted in chloroform containing a pyrazine standard as previously described (40) generating well-resolved spectra (online Supplementary Fig. S1).…”

Foraging theory and the propensity to be obese: an alternative to thrift

“…In brown bears that habitually hibernate, fat accumulation is not associated with adverse metabolic effects including insulin resistance, glucose intolerance and systemic inflammation (Arinell et al 2012;Sommer et al 2016;Stenvinkel et al 2013). Black tailed godwits have a sufficiently plastic lipid metabolism that enables them to manage energy requirement of migration independent of diet composition (Viegas et al 2017). On the contrary diet composition is believed to be a contributor to human obesity (Astrup & Brand-Miller 2012;Buettner et al 2007;Miller et al 1990;Tucker et al 1997).…”

Peak Abundance of Fatty Acids From Intertidal Biofilm in Relation to the Breeding Migration of Shorebirds

“…Further, algae are the main producers (globally) of critically important long-chain polyunsaturated fatty acids (LC-PUFA), including eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) (Hixson et al, 2015). These PUFA are essential to many vertebrates, including birds (Viegas et al, 2017), which benefit from ingesting at least some PUFA (pre-formed) in their diets (Arts et al, 2001).…”