Transcribed dinucleotide microsatellites and their associated genes from channel catfish Ictalurus punctatus

The presence of trinucleotide microsatellites within genes is a well-known cause for a number of genetic diseases. However, the precise distribution o f dinucleotide microsatellites within genes is less well documented. Here w e report 15 unique cDNAs containing dinucleotide repeats from the channel c atfish Ictalurus punctatus. Gene identities of nine of the 15 cDNAs were de termined, of which three encode structural genes, and six encode regulatory proteins. Five cDNAs harbored dinucleotide repeats in the 5' untranslated region (5'-NTR), nine in the 3'-NTR, and one in the coding region. The pres ence of these transcribed dinucleotide repeats and their potential expansio n in size within coding regions could lead to disruption of the original pr otein and/or formation of new genes by frame shift. The low number of dinuc leotide repeats within coding regions suggests that they were strongly sele cted against. All the transcribed microsatellite loci examined were polymor phic making them useful for gene mapping in catfish. (C) 1999 Academic Pres s.