Abstract
Because of the antimicrobial role that defensins play in cows, genes encoding these peptides may be considered as molecular markers of a genetically determined susceptibility of the mammary gland to mastitis. In Friesian and Egyptian cows which were selected based on their milk productivity, 1638-bp beta-defensin genes were amplified. Two PCR amplicon sizes of the gene encoding beta-defensin (1638 bp and 429 bp) were observed in Friesian cows (high milk production), while in Egyptian cows (low milk production) one PCR amplicon size (429 bp) was observed. PCR-RFLP technique was used to discriminate between the common 429 bp band in both Friesian and Egyptian cows, but no difference between them had been observed. DNA sequencing for 1638 bp (B2) and 429 bp (B1) was carried out. Sequence analysis indicated that these two PCR amplicon sizes were two types of genes encoding beta-defensins and very tightly close to each other. Based on their sequence alignment (B1 and B2) with the presented defensin genes in the GenBank, phylogenic tree was constructed. A new gene (B1) belongs to the beta-defensin genes family was detected for the first time and associated to the low milk production in cattle population.
Highlights
Defensins are a group of disulfide-linked cationic antimicrobial peptides that function in vertebrate innate immunity (Aono et al 2006)
Beta-defensin was first isolated from bovine respiratory tract and was named tracheal antimicrobial peptide (TAP) (Diamond et al 1991)
Genotyping for the defensin gene using restriction fragment length polymorphism (RFLP) technique Purified PCR bands (429 bp) from both Egyptian and Friesian cows were digested with six different restriction enzymes (TaqI, HindIII, NdeII, PstI, PvuII and SmaI)
Summary
Defensins are a group of disulfide-linked cationic antimicrobial peptides that function in vertebrate innate immunity (Aono et al 2006). Innate immunity is highly conserved from fruit flies to human and is the first line of defense against invading pathogens (Yuan and Walker 2004). Defensins act as direct antimicrobial effectors by disrupting membrane integrity and function, which leads to the lysis of the microorganisms (Yang et al 2002). Α- and β-defensins, differ in length and pairing of the six cysteines (Selsted and Ouellette 2005). Alpha- and beta-defensins are salt-sensitive and the direct antimicrobial effect occurs in vacuoles of phagocytes and on mucosal epithelia, where there is low ionic strength (Goldman et al 1997; Yang et al 2002). Beta-defensin was first isolated from bovine respiratory tract and was named tracheal antimicrobial peptide (TAP) (Diamond et al 1991)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call