Zoological Studies

Vol. 46 No. 6, 2007

Molecular Characterization of Major Histocompatibility Complex Class II DQB and DRB Genes in Bottlenose Dolphins (Tursiops truncatus and T. aduncus) from the Western Pacific

Wei-Cheng Yang, Lien-Siang Chou, and Jer-Ming Hu*

Institute of Ecology and Evolutionary Biology, National Taiwan University, 1 Roosevelt Rd., Sec. 4, Taipei 106, Taiwan

Wei-Cheng Yang, Jer-Ming Hu, and Lien-Siang Chou (2007) Variability of the major histocompatibility complex is very suitable for investigating a wide range of open questions in evolutionary ecology and conservation because it reflects evolutionarily relevant and adaptive processes within and between populations. Herein, we present the first full-length expressed DQB and DRB gene products in the order Cetacea from 2 species of bottlenose dolphins (genus Tursiops, family Delphinidae) of the western Pacific that differ in their diet, microflora, and habitat. These species might represent a natural model through which we can examine the immunogenetic consequences of different pathogenic and environmental influences on the MHC of mammals. Blood samples from 2 T. aduncus (from Taiwan and Indonesia) and 2 T. truncatus (from Taiwan and Japan) were used for RACE-PCR. The presence of 1 DQB locus and 2 DRB loci in this genus was revealed. The presence of TutrDQB, Tuad-DRB, and Tutr-DRB suggests a functional role for these molecules in pathogen-specific immune responses. However, several features do not support a traditional role for Tuad-DQB molecules in peptide binding, and further study is needed. The phylogenetic analysis revealed that the sequence divergence of these 2 species might reflect different selective pressures between pathogens in oceanic (T. truncatus) and coastal (T. aduncus) waters. This study provides an essential foundation for analyzing variations in MHC genes and studying infectious disease ecology in bottlenose dolphins.

Key words: Major histocompatibility complex, Bottlenose dolphins, Tursiops.

*Correspondence: Jer-Ming Hu and Lien-Siang Chou contributed equally to this work. Tel: 886-2-33662472. Fax: 886-2-33662473. E-mail:jmhu@ntu.edu.tw