Organization of the histone genes in the rainbow trout (Salmo gairdnerii).

Twelve clones containing histone genes were isolated from a genomic trout library constructed in the vector Charon 4A. Each of the clones was found to contain a conserved 10.2-kb Eco RI fragment that contained one copy of each of the histones in the order H4-H2B-H1-H2A-H3, all of which are transcribed from the same strand. Genomic Southern blots indicate that these clusters are representative of the vast majority of the histone genes in the trout. Tandemly linked clusters were not found. Approximately 145 copies of this cluster are present in a trout sperm cell. Sequence analysis has shown the genes to be without introns and to show strong selection for codons ending in C or G. Consensus signals similar to those found in other histone genes are present in the flanking regions.