The molecular underpinnings of metabolic adaptation to seasons are poorly understood in long- distance migrants. We measured changes in physiology and performed de novo sequencing of RNA extracted from liver samples collected at 4-h intervals over a period of 24 h from a long-distance avian migrant, the blackheaded bunting (Emberiza melanocephala), during two states: photostimulated vernal migratory (M) state and photorefractory non-migratory (nM) state. The M state was differentiated from the nM state based on body fattening and weight gain, as well as on Zugunruhe, that is, nocturnal migratory restlessness in caged birds. We found that baseline blood glucose and triglyceride levels were significantly higher in the M state than the nM state; conversely, surface body temperature was higher in the nM state than the M state. In a total of 6 liver samples that were sequenced from each state, 11,246 genes were annotated, including 4448 genes that were cyclic over 24 h. We found 569 differentially expressed genes (DEGs) between the M and the nM state, and the M state showed 131 upregulated and 438 downregulated genes. These DEGs formed core gene hubs associated with specific biological processes in both the states. In addition, weighted gene coexpression network analysis revealed two discrete modules of coexpressed genes, with a significant difference in the expression pattern of metab olism-associated genes between M and nM states. These results demonstrate, for the first time, transcriptome-wide changes in the liver between two distinct physiological states and give molecular insights into seasonal metabolic adaptations in latitudinal migrants.
|Journal||Frontiers in Physiology|
|State||Published - Nov 27 2018|
Bibliographical noteFunding Information:
The help rendered by Prof. Sangeeta Rani in the sampling is acknowledged. We thank Prof. Satchidananda Panda, Salk Institute for Biological Studies, La Jolla, CA, United States for the help and advice for RNA-Seq. Ms. Aakansha Sharma helped in the organization of the manuscript at various stages. Funding. This research was funded by Department of Biotechnology, New Delhi through a research grant (BT/PR4984/MED/30/752/2012) to VK. DS was funded by DST-SERB young scientist award (YSS/2015/001682).
© Copyright © 2018 Singh, Swarup, Le and Kumar.
- gene expression
ASJC Scopus subject areas
- Physiology (medical)