Biology Faculty Articles

Title

Diversity and Duplication of DQB and DRB-Like Genes of the MHC in Baleen Whales (Suborder: Mysticeti)

Document Type

Article

Publication Date

5-2006

Publication Title

Immunogenetics

Keywords

Overdominant selection, Diversity, Cetaceans, Dolphins

ISSN

0093-7711

Volume

58

Issue/No.

4

First Page

283

Last Page

296

Abstract

The molecular diversity and phylogenetic relationships of two class II genes of the baleen whale major histocompatibility complex were investigated and compared to toothed whales and out-groups. Amplification of the DQB exon 2 provided sequences showing high within-species and between-species nucleotide diversity and uninterrupted reading frames consistent with functional class II loci found in related mammals (e.g., ruminants). Cloning of amplified products indicated gene duplication in the humpback whale and triplication in the southern right whale, with average nucleotide diversity of 5.9 and 6.3%, respectively, for alleles of each species. Significantly higher nonsynonymous divergence at sites coding for peptide binding (32% for humpback and 40% for southern right) suggested that these loci were subject to positive (overdominant) selection. A population survey of humpback whales detected 23 alleles, differing by up to 21% of their inferred amino acid sequences. Amplification of the DRB exon 2 resulted in two groups of sequences. One was most similar to the DRB3 of the cow and present in all whales screened to date, including toothed whales. The second was most similar to the DRB2 of the cow and was found only in the bowhead and right whales. Both loci showed low diversity among species and apparent loss of function or altered function including interruption of reading frames. Finally, comparison of inferred protein sequence of the DRB3-like locus suggested convergence with the DQB, perhaps resulting from intergenic conversion or recombination.

Comments

©Springer-Verlag 2006

ORCID ID

0000-0001-7353-8301

ResearcherID

N-1726-2015

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