Coding sequences of the MHC II beta chain of homozygous rainbow trout (Oncorhynchus mykiss)

Six lines of homozygous rainbow trout (Oncorhynchus mykiss) from different genetic and geographical backgrounds have been produced as aquatic models f or biomedical research by the chromosome set manipulation techniques of and rogenesis and gynogenesis. Messenger RNA from spleens was extracted, and th e MHC II B cDNA sequences, amplified by RT-PCR, were cloned into plasmids. Sequences of the MHC II beta 2 domains were highly conserved between the di fferent plasmids from the same and different lines of trout, Most of the va riability among sequences was found in the amino terminal half of the beta 1 domain, which corresponds with the peptide binding region of the MHC II m olecule. This diversity suggests that the different lines of trout may exhi bit differences in immune response, Rainbow trout MHC II B sequences were s imilar to the MHC II B sequences of the Pacific salmon (O. gorbuscha, O. ts hawytscha, O. nerka, O. masou, O. kisutch). Southern blot analysis performe d on the restricted DNA of the OSU and Hot Creek trout, and the doubled hap loid progeny produced by androgenesis from OSU x Hot Creek hybrids indicate s that two distinct genes encode the,MHC II B sequences and that these gene s are unlinked. (C) 1999 Elsevier Science Ltd. All rights reserved.