The late-evolving salmon and trout join the GnRH1 club.

Autor: von Schalburg KR; Department of Biology, Electron Microscopy Laboratory, University of Victoria, Victoria, BC, V8W 3N5, Canada. krvs@uvic.ca., Gowen BE; Department of Biology, Electron Microscopy Laboratory, University of Victoria, Victoria, BC, V8W 3N5, Canada., Christensen KA; Department of Biology, University of Victoria, Victoria, BC, V8W 3N5, Canada., Ignatz EH; Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, A1C 5S7, Canada., Hall JR; Aquatic Research Cluster, CREAIT Network, Ocean Sciences Centre, Memorial University of Newfoundland, St. John's, NL, A1C 5S7, Canada., Rise ML; Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, A1C 5S7, Canada.
Jazyk: angličtina
Zdroj: Histochemistry and cell biology [Histochem Cell Biol] 2023 Dec; Vol. 160 (6), pp. 517-539. Date of Electronic Publication: 2023 Aug 11.
DOI: 10.1007/s00418-023-02227-z
Abstrakt: Although it is known that the whitefish, an ancient salmonid, expresses three distinct gonadotropin-releasing hormone (GnRH) forms in the brain, it has been thought that the later-evolving salmonids (salmon and trout) had only two types of GnRH: GnRH2 and GnRH3. We now provide evidence for the expression of GnRH1 in the gonads of Atlantic salmon by rapid amplification of cDNA ends, real-time quantitative PCR and immunohistochemistry. We examined six different salmonid genomes and found that each assembly has one gene that likely encodes a viable GnRH1 prepropeptide. In contrast to both functional GnRH2 and GnRH3 paralogs, the GnRH1 homeolog can no longer express the hormone. Furthermore, the viable salmonid GnRH1 mRNA is composed of only three exons, rather than the four exons that build the GnRH2 and GnRH3 mRNAs. Transcribed gnrh1 is broadly expressed (in 17/18 tissues examined), with relative abundance highest in the ovaries. Expression of the gnrh2 and gnrh3 mRNAs is more restricted, primarily to the brain, and not in the gonads. The GnRH1 proximal promoter presents composite binding elements that predict interactions with complexes that contain diverse cell fate and differentiation transcription factors. We provide immunological evidence for GnRH1 peptide in the nucleus of 1-year-old type A spermatogonia and cortical alveoli oocytes. GnRH1 peptide was not detected during other germ cell or reproductive stages. GnRH1 activity in the salmonid gonad may occur only during early stages of development and play a key role in a regulatory network that controls mitotic and/or meiotic processes within the germ cell.
(© 2023. The Author(s).)
Databáze: MEDLINE
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