A photoperiodic molecular response in migratory redheaded bunting exposed to a single long day.
A long day response is triggered by the activation of EYA3 (eyes absent 3) and TSH-β (thyroid stimulating hormone beta subunit) genes in the pars tuberalis (PT). However, protein products of these genes are not yet shown in the hypothalamus of a photoperiodic species. Therefore, using the 'first long day paradigm', EYA3 and TSH-β along with c-FOS and GnRH peptides were immunohistochemically localized and measured in the hypothalamus of photoperiodic redheaded buntings that were maintained on short days (SD, LD 8/16) and subjected to one full long day (LD, LD 16/8). Following morning light remained turned off, and birds were sacrificed in the first hour of the day. Brains were collected and processed for immunohistochemistry of peptides. FOS-lir and GnRH-lir cells were significantly higher in the preoptic area (POA) in LD than in SD, which indicated photoperiod induced neuronal activation and downstream effects, respectively, under LD. In LD, EYA3-lir cells were significantly increased in septal lateralis (SL) with fibres extending to sub-septal organ (SSO); EYA3 fibres were very dense in median eminence. Similarly, there were significantly increased TSH-β-lir cells in the ventricular region with much abundance in the PT and TSH-β-lir fibres in the SSO (extending up to SL), inferior hypothalamic nucleus (IH) and infundibular nucleus (IN) in LD birds. Elevated EYA3, TSH-α and TSH-β mRNA levels further confirmed photoperiodic induction at the transcriptional level in buntings on the first long day. These are the first results showing localization of photoperiodically induced peptides in the hypothalamus of a songbird species, the redheaded bunting.
DST-IRHPA Center for Excellence in Biological Rhythms Research, Department of Zoology, University of Delhi, Delhi 110 007, India.
Gaurav
G
Majumdar
DST-IRHPA Center for Excellence in Biological Rhythms Research, Department of Zoology, University of Lucknow, Lucknow 226 007, India.
Garima
G
Yadav
DST-IRHPA Center for Excellence in Biological Rhythms Research, Department of Zoology, University of Lucknow, Lucknow 226 007, India.
Sangeeta
S
Rani
DST-IRHPA Center for Excellence in Biological Rhythms Research, Department of Zoology, University of Delhi, Delhi 110 007, India. Electronic address: drvkumar11@yahoo.com.
Vinod
V
Kumar
D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D015292:Glycoprotein Hormones, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism*; D007031:Hypothalamus / Q000378:metabolism; D007124:Immunoenzyme Techniques; D008027:Light; D046109:Passeriformes / Q000502:physiology*; D017440:Photoperiod; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D037322:Thyrotropin, beta Subunit / Q000235:genetics / Q000378:metabolism*
D005136:Eye Proteins; D015292:Glycoprotein Hormones, alpha Subunit; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D037322:Thyrotropin, beta Subunit; D007987:Gonadotropin-Releasing Hormone
Bunting; EYA3; GnRH; Photoperiodic induction; TSH-β; c-FOS