Night Migratory Songbirds Exhibit Metabolic Ability to Support High Aerobic Capacity during Migration

Abstract

Aerobic metabolism in night migratory songbirds exhibit seasonal plasticity, which depends not only on annual life history stages (LHSs), viz., migratory/nonmigratory or breeding/ nonbreeding, but also on the time of the day. Initially, we studied daily changes in behavior/physiology alongside aerobic metabolism intermediates using gas chromatography−mass spectrometrybased chemometric analyses of serum of migratory male redheaded buntings during low-energy wintering, that is, the nonmigrating LHS. Then, the metabolic phenotype of nonmigrating birds was compared with that of photostimulated migrating buntings, the latter representing the high-energy LHS. Diurnal changes such as daytime feeding and activity were reflected by increased fatty acid (FA, viz., palmitic, oleic, and linoleic acids) levels and protein catabolites, whereas higher night-time levels of short-chain FAs indicated lipolysis in night-fasted birds. High night-time levels of taurine, a sulfur amino acid, suggested the endogenous metabolite rendering an adaptive advantage to hyperglycaemic night migratory songbirds during the LHS with low daily energy expenditure. Conversely, migrating birds, largely night-active, exhibited higher circulatory FA, its mobilization, and increased aerobic catabolism, and the adipocyte-secreted lipid, palmitoylethanolamide (PEA), capable of activating the peroxisome proliferator-activated receptor α−PGCα axis, showed elevated levels throughout the day. PEA is known for anti-inflammatory and cannabinomimetic properties, and we show, for the first time, circadian changes in PEA levels in any migrating bird. Significantly higher levels of pyridoxal phosphate also suggested the bird's protective ability to combat metabolic stress through high aerobic capacity during migration. This study elucidates putative "serum biomarkers" with a protective role in stress accrued by enhanced aerobic capacity requirements at the organismal level.

Altered dynamics of mitochondria and reactive oxygen species in the erythrocytes of migrating red-headed buntings

“…FABP3 is a fatty acid carrier in blood, whose mRNA expression began to alter during pMig but enhanced significantly from pMig to Mig states. The upregulation of FABP3 expression is correlated with the increased utilization of FA during migration ( Gugleilmo, 2010 ; Gupta et al, 2020 ). The mRNA expression of ATGL, DGAT2, and GOT2 also increased from nMig to Mig transition with much overexpression during Mig.…”

“…For group 2, body weight and blood sample collection was initiated on days 0, 7, and 28 when birds exhibited simulated nonmigratory (nMig), pre-migratory (pMig), and migratory (Mig) annual life history states. About 25-50 μL of blood was drawn from the left brachial wing vein (see Gupta et al, 2020 for more details) and Frontiers in Physiology frontiersin.org suspended in tubes with equal amounts of PBS (phosphate buffer saline) containing 5 mM EDTA. Nearly 32-36 h after the first blood collection, in group 2, 50 μL of blood was drawn from the right brachial wing vein for hematocrit analysis.…”

“…Regular flight during migration stimulates antioxidant protection in addition to fat catabolic pathways. For example, mitochondrial fatty acid oxidation co-occurs with a rise in palmitoylethanolamide, PEA levels, which have anti-inflammatory and cannabinomimetic properties ( Gupta et al, 2020 ). Increased transcriptional activity of genes (fatty acid transporter, CD36; fatty acid binding protein, FABP; glutamic-oxaloacetic transaminase; GOT2, diacylglycerol acyl transferase DGAT2 and adipose triglyceride lipase, ATGL) implicated in fat internalization, transport, and breakdown in the liver and/or muscle has been shown in buntings ( Sharma et al, 2021 ).…”

“…Migratory buntings ( Emberiza species) exhibit pre-migratory hyperphagia, an increase in body weight, hormones (for example, thyroxine; please see Jain and Kumar, 1995 ), trigger of intense night-flight behavior ( Gupta and Kumar, 2013 ), and the metabolic ability to support high aerobic capacity ( Gupta et al, 2020 ). In the present study, we sought to comprehensively outline seasonal changes in blood biochemistry and cytology of red-headed buntings, such as reticulocyte regeneration, hematocrit changes, MMP, ROS, apoptosis, and changes in the concentration of selected genes implicated in the ROS and energy metabolism.…”

Ecological Environment and Pollution Control under the Influence of Modern Biotechnology Development

“…The emergence of modern BT has made enterprises and the public more aware of the economic value it produces, while ignoring the EV of modern BT, thereby causing great pollution to the environment while improving production efficiency and economic benefits, hindering modern BT The realization of EV of technology. Therefore, even in cities with high economic level, the public's awareness of the pollution caused by BT is not strong enough, and the awareness of ecological environmental protection is still relatively weak [15][16].…”