This article is part of a series on Bovine: the companion papers for the publication of the bovine genome sequence.

Research article

Bos taurus genome sequence reveals the assortment of immunoglobulin and surrogate light chain genes in domestic cattle

Anna Ekman¹ , Mikael Niku² , Jenni Liljavirta¹ and Antti Iivanainen¹

¹Department of Basic Veterinary Sciences, University of Helsinki, Helsinki, Finland

²Department of Applied Chemistry and Microbiology, University of Helsinki, Helsinki, Finland

author email corresponding author email

BMC Immunology 2009, 10:22doi:10.1186/1471-2172-10-22

Published:	30 April 2009

Abstract

Background

The assortment of cattle immunoglobulin and surrogate light chain genes has been extracted from the version 3.1 of Bos taurus genome sequence as a part of an international effort to sequence and annotate the bovine genome.

Results

63 variable lambda chain and 22 variable kappa chain genes were identified and phylogenetically assigned to 8 and 4 subgroups, respectively. The specified phylogenetic relationships are compatible with the established ruminant light chain variable gene families or subgroups. Because of gaps and uncertainties in the assembled genome sequence, the number of genes might change in the future versions of the genome sequence. In addition, three bovine surrogate light chain genes were identified. The corresponding cDNAs were cloned and the expression of the surrogate light chain genes was demonstrated from fetal material.

Conclusion

The bovine kappa gene locus is compact and simple which may reflect the preferential use of the lambda chain in cattle. The relative orientation of variable and joining genes in both loci are consistent with a deletion mechanism in VJ joining. The orientation of some variable genes cannot be determined from the data available. The number of functional variable genes is moderate when compared to man or mouse. Thus, post-recombinatorial mechanisms might contribute to the generation of the bovine pre-immune antibody repertoire. The heavy chains probably contribute more to recombinational immunoglobulin repertoire diversity than the light chains but the heavy chain locus could not be annotated from the version 3.1 of Bos taurus genome.