Developmental expression, alternative splicing and gene copy number for the pituitary adenylate cyclase-activating polypeptide (PACAP) and growth hormone-releasing hormone (GRF) gene in rainbow trout.
Both growth hormone-releasing hormone (GRF) and pituitary adenylate cyclase-activating polypeptide (PACAP) are encoded on the same gene in fish, but not in mammals. Our objective was to examine the onset and pattern of expression for the grf/pacap gene and to determine whether there is more than one gene in rainbow trout. The results show that grf/pacap mRNA is first expressed at 4 days after fertilization and continues through to hatching. Alternative splicing at all developmental stages produces a full-length transcript and one lacking exon four, which encodes GRF. Thus, independent regulation of the hormones occurs throughout development. Southern analysis shows that two grf/pacap genes exist in trout, but only one gene is responsible for the two identified transcripts. Overexpression of the grf/pacap gene in transgenic fish was attempted, but did not succeed. We conclude that the early and continued expression of grf/pacap mRNA in trout embryos and regulation of the neuropeptide ratio suggests they have a role in early brain development apart from their later role in releasing pituitary hormones.
Krueckl
S L
SL
Department of Biology, University of Victoria, Victoria, British Columbia, Canada V8W 2Y2.
Sherwood
N M
NM
D017398:Alternative Splicing; D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D015139:Blotting, Southern; D001921:Brain / Q000196:embryology; D004625:Embryo, Nonmammalian / Q000378:metabolism; D018628:Gene Dosage; D018507:Gene Expression Regulation, Developmental; D013007:Growth Hormone-Releasing Hormone / Q000235:genetics*; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000235:genetics*; D017686:Oncorhynchus mykiss / Q000196:embryology / Q000235:genetics / Q000502:physiology*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012333:RNA, Messenger; D013007:Growth Hormone-Releasing Hormone