Presence and developmental regulation of serotonin N-acetyltransferase transcripts in oocytes and early quail embryos (Coturnix coturnix japonica)

• Published in: Molecular reproduction and development Vol. 65; no. 2; pp. 132 - 140
• Main Authors: Oblap, Ruslan, Olszańska, Bożenna
• Format: Journal Article
• Language: English
• Published: New York Wiley Subscription Services, Inc., A Wiley Company 01-06-2003; Wiley-Liss
• Subjects: Animals; Arylamine N-Acetyltransferase - biosynthesis; Arylamine N-Acetyltransferase - metabolism; avian oocyte; Base Sequence; Biological and medical sciences; Coturnix - embryology; embryo; Embryo, Nonmammalian - enzymology; Fundamental and applied biological sciences. Psychology; Gene Expression Profiling; Gene Expression Regulation, Developmental; Hormones and neuropeptides. Regulation; Hypothalamus. Hypophysis. Epiphysis. Urophysis; Japanese quail; melatonin; Molecular Sequence Data; Oocytes - enzymology; pineal gland; Reverse Transcriptase Polymerase Chain Reaction; serotonin N-acetyltransferase transcription; Vertebrates: endocrinology; Acyltransferases; Embryo; Melatonin; Endocrine gland; Enzyme; Transferases; Pineal body; Germinal cell; Coturnix japonica; Gene expression; In vitro; Vertebrata; Aves; Aralkylamine N-acetyltransferase; Comparative study; Oocyte; Pineal hormone
• ISSN: 1040-452X; 1098-2795
• DOI: 10.1002/mrd.10236

By RT‐PCR two transcripts for arylalkylamine N‐acetyltransferase (AA‐NAT; serotonin N‐acetyltransferase; EC 2.3.1.87), the key enzyme in melatonin synthesis, were found, for the first time, in the oocytes and blastoderms from freshly laid eggs (323‐ and 238‐bp RT‐PCR products), and one (238‐bp product) in the pineal gland of Japanese quail (Coturnix coturnix japonica). The two products differed by an intron of 85‐bp present in the 323‐bp band and absent from the 238‐bp band. The identity of the products was confirmed by restriction analysis and sequencing. The ratio of the 323:238‐bp bands changed during oogenesis from ∼17:1 in small 3‐mm oocytes to ∼4:1 in immature vitellogenic oocytes and ∼1:1 in mature, preovulatory oocytes; it was reversed to ∼0.2:1 in blastoderms from fertile freshly laid eggs, corresponding to embryo of ∼40,000 cells. It is proposed that the longer 323‐bp product, containing an intron, represents a translationally inactive form of the transcript, stored in maternal RNA. The shorter 238‐bp product lacking an intron may represent the mature active AA‐NAT mRNA found in the pineal gland and in early embryos, and—to a lower proportion—in older oocytes. These data constitute the first direct proof of an intron sequence in maternal RNA of avian oocyte. It is possible that differential processing of the immature mRNA is part of a transcriptional regulation mechanism of AA‐NAT activity. A possible role of extrapineal melatonin in early avian development is discussed. Mol. Reprod. Dev. 65: 132–140, 2003. © 2003 Wiley‐Liss, Inc.