Transition from embryonic to adult transcription pattern of serotonin N-acetyltransferase gene in avian pineal gland

• Published in: Molecular reproduction and development 2004-02, Vol.67 (2), p.145-153
• Main Authors: OBLAP, Ruslan, OLSZANSKA, Bozenna
• Format: Article
• Language: English
• Subjects: Animals; arylalkylamine N-acetyltransferase; Arylalkylamine N-Acetyltransferase - genetics; Base Sequence; Biological and medical sciences; Coturnix - embryology; Coturnix - genetics; Coturnix - growth & development; Coturnix coturnix; DNA - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Developmental; Hormones and neuropeptides. Regulation; Hypothalamus. Hypophysis. Epiphysis. Urophysis; Japanese quail; melatonin receptors; melatonin synthesis; Pineal Gland - embryology; Pineal Gland - growth & development; Pineal Gland - metabolism; pineal gland development; Receptors, Melatonin - genetics; Reverse Transcriptase Polymerase Chain Reaction; RNA Processing, Post-Transcriptional; RNA, Messenger - genetics; RNA, Messenger - metabolism; transcription; Transcription, Genetic; Vertebrates: endocrinology
• ISSN: 1040-452X; 1098-2795
• DOI: 10.1002/mrd.10391

The study reports the change of transcription pattern of serotonin N‐acetyltransferase gene and melatonin receptor genes during ontogenesis of the avian pineal gland. The RT‐PCR technique was used to investigate the expression of the arylalkylamine N‐acetyltransferase (AA‐NAT) and melatonin receptor genes during development of the pineal glands isolated from Japanese quail (Coturnix coturnix japonica) embryos incubated from 3 days on until hatching (17 days), and in some organs (pineal, brain hemisphere, eye, leg, heart) of the 3‐day‐old quail embryo. It was shown that two phases of AA‐NAT expression are observed during pineal gland development. The first, embryonic‐type phase, lasts from the beginning until 7–10 days of incubation, and is marked by the presence of two RT‐PCR products for AA‐NAT: the shorter mature form without intron (238 bp), and the longer form (323 bp) containing an unprocessed intron of 85 bp. The second, adult‐type phase is characterized by the presence of a single mature transcript, containing no intron; it starts from 7 to 10 days of incubation and lasts until hatching and in the adult pineal. The duration of this transition time from the embryonic to the adult transcription pattern in the quail pineal gland from 7 to 10 days of incubation we attribute to asynchronic embryo development, because quail chicks usually hatch between the 16th and 19th day of incubation. Analysis of the AA‐NAT protein sequences for chick and quail (GeneBank accession no. U 46 502 and AF 007 068, respectively) revealed their perfect homology with the part of protein read from the sequence present in the adult‐type phase of the pineal gland (the RT‐PCR product of 238 bp). The presence of the intron (in the 323 bp RT‐PCR product, accession no. AY 197 460) in the embryonic‐phase of the pineal gland changes the reading frame of the mRNA sequence and the hypothetical resulting protein loses its homology with the chick and quail AA‐NAT enzyme starting with 105th amino acid of the complete chick AA‐NAT protein comprising 205 amino acids (accession no. U 46 502). In the whole embryos at stages 1–8 (according to the Hamburger–Hamilton classification) both RT‐PCR products with and without intron were consistently found, and individual tissues from 3‐day‐old embryos also produced two AA‐NAT products, i.e., the expression was of the embryonic‐type. At the time of transition from the embryonic to the adult AA‐NAT transcription pattern, in 7–11‐day‐old embryos, all thr