Biology subjects

Balakrishnan, C. N.

Publications and source records attributed to Balakrishnan, C. N..

3 recordsLinked to original sources

bioRxiv2018

Co-regulation of hormone receptors, neuropeptides, and steroidogenic enzymes across the vertebrate social behavior network

The vertebrate basal forebrain and midbrain contain a set of interconnected nuclei that control social behavior. Conserved anatomical structures and functions of these nuclei have now been documented among fish, amphibians, reptiles, birds and mammals, and these brain regions have come to be known as the vertebrate social behavior network (SBN). While it is known that nuclei (nodes) of the SBN are rich in steroid and neuropeptide activity linked to behavior, simultaneous variation in the expression of neuroendocrine genes among several SBN nuclei has not yet been described in detail. In this study, we use RNA-seq to profile gene expression across seven brain regions representing five nodes of the vertebrate SBN in a passerine bird, the wire-tailed manakin Pipra filicauda. Using weighted gene co-expression network analysis (WGCNA), we reconstructed sets of coregulated genes, revealing striking patterns of variation in neuroendocrine gene expression across the SBN. We describe regional expression variation networks comprising a broad set of hormone receptors, neuropeptides, steroidogenic enzymes, catecholamines, and other neuroendocrine signaling molecules. Our findings highlight how heterogeneity of brain gene expression across the SBN can provide functional insights into the neuroendocrine and genetic mechanisms that underlie vertebrate social behavior.

neuroscience↗

bioRxiv2018

The variability of song variability in wild and domesticated zebra finches Taeniopygia guttata

Birdsong is a classic example of a learned social behavior. Like many traits of interest, however, song production is also influenced by genetic factors and understanding the relative contributions of genetic and environmental influences remains a major research goal. In this study we take advantage of genetic variation among captive zebra finch populations to examine variation in a population-level song trait: song variability. We find that zebra finch populations differ in levels of song variability. Domesticated T. g. castanotis populations displayed higher song diversity than more recently wild-derived populations of both zebra finch subspecies T. g. castanotis and T. g. guttata, the Timor zebra finch. To determine whether these differences could have a genetic basis, we cross-fostered domesticated T. g. castanotis and Timor zebra finches to Bengalese finches Lonchura striata domestica. Following cross-fostering, domesticated T. g. castanotis maintained a higher level of song diversity than T. g. guttata. We suggest that the high song variability of domesticated zebra finches may be a consequence of reduced purifying selection acting on song traits. Intraspecific differences in the mechanisms underlying song variability therefore represent an untapped opportunity for probing the mechanisms of song learning and production.

animal behavior and cognition↗

bioRxiv2017

Transcriptional response to West Nile virus infection in the zebra finch (Taeniopygia guttata), a songbird model for immune function

West Nile Virus (WNV) is the one of most widespread arboviruses worldwide. WNV exists in a bird-mosquito transmission cycle where passerine birds act as the primary reservoir host. As a public health concern, the mammalian immune response to WNV has been studied in detail. Little, however, is known about the avian immune response to WNV. Avian taxa show variable susceptibility to WNV and what drives this variation is unknown. Thus, to study the immune response to WNV in birds, we experimentally infected captive zebra finches (Taeniopygia guttata). Zebra finches provide a useful model, as like many natural avian hosts they are moderately susceptible to WNV and thus provide sufficient viremia to infect mosquitoes. We performed splenic RNAseq during peak viremia to provide an overview of the transcriptional response. In general, we find strong parallels with the mammalian immune response to WNV, including up-regulation of five genes in the Rig-I-like receptor signaling pathway, and offer insights into avian specific responses. Together with complementary immunological assays, we provide a model of the avian immune response to WNV and set the stage for future comparative studies among variably susceptible populations and species.

genomics↗