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Open Access Research article

A physical map of a BAC clone contig covering the entire autosome insertion between ovine MHC Class IIa and IIb

Gang Li12, Ka Liu25, Shasha Jiao12, Haibo Liu2, Hugh T Blair34, Peng Zhang25, Xiaoran Cui2, Pingping Tan2, Jianfeng Gao14* and Runlin Z Ma2456*

Author affiliations

1 School of Life Sciences, Shihezi University, Xinjiang 832003, China

2 State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Science, Beijing 100101, China

3 Institute of Veterinary Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand

4 Joint Research Center for Sheep Breeding and Developmental Biology, IGDB-Massey University, Massey, New Zealand

5 Graduate University of Chinese Academy of Sciences, Beijing 100149, China

6 Institute of Genetics and Developmental Biology, Chinese Academy of Science, Beijing 100101, China

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Citation and License

BMC Genomics 2012, 13:398  doi:10.1186/1471-2164-13-398

Published: 16 August 2012

Abstract

Background

The ovine Major Histocompatibility Complex (MHC) harbors genes involved in overall resistance/susceptibility of the host to infectious diseases. Compared to human and mouse, the ovine MHC is interrupted by a large piece of autosome insertion via a hypothetical chromosome inversion that constitutes ~25% of ovine chromosome 20. The evolutionary consequence of such an inversion and an insertion (inversion/insertion) in relation to MHC function remains unknown. We previously constructed a BAC clone physical map for the ovine MHC exclusive of the insertion region. Here we report the construction of a high-density physical map covering the autosome insertion in order to address the question of what the inversion/insertion had to do with ruminants during the MHC evolution.

Results

A total of 119 pairs of comparative bovine oligo primers were utilized to screen an ovine BAC library for positive clones and the orders and overlapping relationships of the identified clones were determined by DNA fingerprinting, BAC-end sequencing, and sequence-specific PCR. A total of 368 positive BAC clones were identified and 108 of the effective clones were ordered into an overlapping BAC contig to cover the consensus region between ovine MHC class IIa and IIb. Therefore, a continuous physical map covering the entire ovine autosome inversion/insertion region was successfully constructed. The map confirmed the bovine sequence assembly for the same homologous region. The DNA sequences of 185 BAC-ends have been deposited into NCBI database with the access numbers HR309252 through HR309068, corresponding to dbGSS ID 30164010 through 30163826.

Conclusions

We have constructed a high-density BAC clone physical map for the ovine autosome inversion/insertion between the MHC class IIa and IIb. The entire ovine MHC region is now fully covered by a continuous BAC clone contig. The physical map we generated will facilitate MHC functional studies in the ovine, as well as the comparative MHC evolution in ruminants.

Keywords:
Ovine; MHC; OLA; Physical map; BAC; Comparative mapping