Abstract

The expression and localization of vitellogenin (VTG) receptor (VTGR) mRNA were identified throughout ovarian development in the rainbow trout, Oncorhynchus mykiss. Northern blot confirmed the presence of a transcript (approximately 3.9 kilobases [kb]) that was specific to the ovary. The expression of VTGR mRNA varied throughout ovarian development and was highest in previtellogenic ovaries and in ovaries at the onset of vitellogenesis containing ovarian follicles (OF) from 35 to 600 microm in diameter. In situ hybridization using 35S riboprobes showed that the transcription of the VTGR gene was initiated in OF measuring 45-50 microm in diameter, with transcripts being exclusively localized in the ooplasm. A dramatic increase in mRNA synthesis occurred during previtellogenic growth (OF from 50 to 200 microm); this was followed by a gradual decrease during the vitellogenic growth phase. VTGR mRNA was not detected in OF greater than 1000 microm in diameter (oocytes actively sequestering VTG). Immunocytolocalization of yolk proteins derived from VTG demonstrated that oocytes started to sequester VTG when they were around 300 microm in diameter, shortly after the time of maximal density of VTGR mRNA in the ooplasm. The timing of transcription of the VTGR gene, predominantly during previtellogenesis, suggests that the VTGR is recycled to the oocyte surface during the vitellogenic growth phase.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.