Polymorphism of the IGHA gene in sheep |
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Authors: | Huitong Zhou Jon G H Hickford Qian Fang |
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Institution: | (1) Agriculture and Life Sciences Division, Lincoln University, P.O. Box 84, Canterbury, New Zealand |
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Abstract: | Genetic variation in immunoglobulin A, the most abundant immunoglobulin in mammalian cells, has not been reported in ruminants.
In this study, variation in the immunoglobulin heavy alpha chain constant gene (IGHA) of sheep was investigated by amplification of a fragment that included the hinge coding sequence, followed by single-strand
conformational polymorphism (SSCP) analysis and DNA sequencing. Three novel sequences, each characterized by unique SSCP banding
patterns, were identified. One or two sequences were detected in individual sheep and all the sequences identified shared
high homology to the published ovine and bovine IGHA sequences, suggesting that these sequences represent allelic variants of the IGHA gene in sheep. Sequence alignment showed that these sequences differed mainly in the 3′ end of exon 1 and in the coding sequence
of the hinge region. There was either a deletion or an insertion of two codons in the hinge coding region in these allelic
variants. Codon usage in the hinge coding region was quite different from that in the non-hinge coding regions of the gene,
suggesting different evolution of the IGHA hinge sequence. Three novel amino acid sequences of ovine IGHA were also predicted, and variation in these sequences might not only affect antigen recognition but also susceptibility to
cleavage by bacterial or parasitic proteases.
Nucleotide sequence data reported in this paper have been submitted to the NCBI GenBank nucleotide sequence database and have
been assigned the accession nos. AY956424–AY956426. |
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Keywords: | Sheep IgA IGHA gene Hinge Polymorphism |
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