Migration-induced variation of fatty acid transporters and cellular metabolic intensity in passerine birds

Abstract

Because lipids are the main fuel supporting avian endurance activity, lipid transport and oxidation capacities may increase during migration. We measured enzyme activities, mRNA expression and protein levels in pectoralis and heart for several key steps of lipid transport and catabolism pathways to investigate whether these pathways were upregulated during migration. We used yellow-rumped (Setophaga coronata) and yellow (S. petechia) warblers and warbling vireos (Vireo gilvus) as study species because they all show migration-induced increases in organismal metabolic capacities. For yellow-rumped warblers, β-hydroxyacyl CoA-dehydrogenase (HOAD) activities and fatty acid transporter mRNA and/or protein levels were higher during spring than fall in pectoralis and heart, except that fatty acid translocase (FAT/CD36) protein levels showed the opposite pattern in heart. Lipid transporter protein levels, but not mRNA expression, in pectoralis and heart of warbling vireos were higher either during spring or fall than summer, but this was not true for HOAD activities. For yellow warblers, pectoralis, but not heart, protein levels of lipid transporters were upregulated during migration relative to summer, but this pattern was not evident for mRNA expression or HOAD activity. Finally, muscle and heart citrate synthase and carnitine palmitoyl transferase activities showed little seasonal variation for any species. These data suggest that pectoralis and heart lipid transport and catabolism capacities are often, but not universally, important correlates of elevated organismal metabolic capacity during migration. In contrast, migration-induced variation in cellular metabolic intensity and mitochondrial membrane transport are apparently not common correlates of the migratory phenotype in passerines.

Acute cold and exercise training upregulate similar aspects of fatty acid transport and catabolism in house sparrows, Passer domesticus

“…Pectoralis FAT/CD36 protein levels increased during migration relative to summer for warbling vireos (Vireo gilvus) and yellow warblers (Setophaga petchia) and increased during spring relative to fall migration for yellow-rumped warblers (Setophaga coronata), consistent with changes in organismal metabolic capacities (Swanson and Dean, 1999;Zhang et al, 2015a). Pectoralis FABP pm protein levels also showed a similar seasonal pattern of variation for yellow and yellow-rumped warblers, but not for warbling vireos, which showed seasonally stable protein levels (Zhang et al, 2015c). Thus protein levels of both FAT/CD36 and FABP pm in skeletal muscles generally increase under conditions of elevated energy demands in both birds and mammals, but such increases are not universal.…”

Obese super athletes: fat-fueled migration in birds and bats

“…Interestingly, fatty acid transporters and oxidative enzymes did not change in cardiac muscle during migration in captive photostimulated white-throated sparrows . Oxidative enzyme activities in the heart were also constant in wild yellow warblers and warbling vireos; however, fatty acid transporters tended to decrease during migration in yellow warblers and increase during migration in warbling vireos (Zhang et al, 2015). These findings emphasize that the regulation of flight muscle fuel metabolism to favor exogenous fatty acids during migration may be decoupled from the heart.…”

“…In the same birds, FABPpm increased by fourfold and twofold at the transcript and protein levels, respectively, in wild migrants (McFarlan et al, 2009), but did not change at the transcript level in captive photostimulated sparrows . H-FABP, FAT/ CD36 and FABPpm protein concentrations of yellow warblers (Setophaga petechia) and warbling vireos (Vireo gilvus) mostly increased during spring and autumn migrations relative to the summer levels, although changes in transcript abundances were less consistent (Zhang et al, 2015). Price et al (2010) did not find any changes in fatty acid transporters or oxidative enzymes in long-daytreated white-crowned sparrows, but attributed these results to a lack of response to photostimulation.…”

The effects of dietary linoleic acid and hydrophilic antioxidants on basal, peak, and sustained metabolism in flight‐trained European starlings

“…Concentration‐dependent negative feedback to 18:2n6 exposure could then explain diet‐specific changes in metabolism over successive cohorts (Fujimori, ; Inoue, Tanabe, & Umesono, ). It is also plausible that diet‐specific changes in metabolism over cohorts and fat loads can be explained by integrating innate circannual‐ and body condition‐based influences on the regulation of oxidative capacity (Batista‐Pinto, Rocha, Castro, Rodrigues, & Lobo‐da‐cunha, ; Corder et al, ; McFarlan et al, ; Zhang, King, Harmon, Eyster, & Swanson, ). The changes in metabolism we observed over the course of this experiment occurred in the absence of external temperature and photoperiod cues.…”