Identification of a sex-linked GH pseudogene in one of two species of Japanese salmon (Oncorhynchus masou and O-rhodurus)

The organization of growth hormone (GH) genes has been examined in two clos ely related species of salmonids from Japan, masu salmon (Oncorhynchus maso u) and amago salmon (O. rhodurus). In two other species of salmonid, coho ( O. kisutch) and chinook (O. tshawytscha), a type-2 GH pseudogene sequence h as been identified on the Y chromosome, and this sequence also appears to b e located on the Y chromosome of 0. masou. Interestingly, despite the close relationship between amago and masu salmon based on mtDNA sequence data, a Y-linked GH sequence was not observed in 0. rhodurus and thus provides a m olecular marker that can distinguish males of these two species. In additio n, the Y-linked GH sequence in masu salmon provides a useful tool for the p roduction of monosex all-female populations for aquaculture. (C) 1999 Elsev ier Science B.V. All rights reserved.