β-Defensin gene copy number variation in cattle.

Area of Science:

• Genomics and Proteomics
• Reproductive Biology
• Immunology

Background:

• Beta-defensins (β-defensins) are antimicrobial peptides with crucial roles in immunity and reproduction.
• Gene copy number variation (CNV) in β-defensin genes is widespread in mammals, potentially affecting traits like fertility and disease resistance.
• Previous studies indicate β-defensins are involved in sperm maturation and function.

Purpose of the Study:

• To comprehensively catalogue bovine β-defensin genes and analyze their copy number variation across breeds.
• To investigate the expression patterns of β-defensin genes during sexual maturation and their correlation with gene copy number.
• To explore the functional implications of β-defensin CNV for cattle fertility.

Main Methods:

• Catalogued 55 β-defensin genes in cattle and constructed a phylogenetic tree to identify human orthologues.
• Assessed β-defensin gene CNV across different cattle breeds, focusing on DEFB103.
• Compared β-defensin gene expression in the testes of calves and adult bulls, and in the epididymis of adult bulls, correlating expression with gene copy number.

Main Results:

• Identified 35 bovine β-defensins with 1:1 human orthologues and discovered extensive CNV across breeds, with DEFB103 exhibiting significant multi-allelic CNV.
• Found that 14 β-defensins, including DEFB103, showed increased expression during sexual maturation.
• Demonstrated a correlation between expression levels and genomic copy numbers for four β-defensins, including DEFB103, in adult bull epididymis.

Conclusions:

• Extensive copy number variation exists in bovine β-defensin genes, particularly DEFB103.
• The observed CNV and expression changes suggest a significant role for β-defensins, especially DEFB103, in cattle reproductive traits and fertility.