Accompaniment of the polymorphism at defensin gene loci with milk productivity in Holstein Friesian and Egyptian cows

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.Zbog antimikrobioloske uloge koju defensin ima kod krava, geni koji kodiraju ove peptide se mogu smatrati molekularnim markerima za genetski odredjenu osetljivost mlecne zlezde na mastitis. Kod frizijskih i egipatskih krava kod kojih se radi selekcija na osnovu njihove mlecnosti, 1638-bp betadefensin geni su pojacani. Kod frizijskih krava su registrovani geni koji kodiraju beta-defensin i to dve PCR velicine amplikona (1638 bp i 429 bp) (visoka proizvodnja mleka), dok kod egipatskih krava (niska proizvodnja mleka) registrovana je jedna PCR velicina amplikona (429 bp). PCR-RFLP tehnika je koriscena za razlikovanje obicnog 429 bp banda kod frizijskih i egipatskih krava, ali nije utvrdjena razlika izmedju njih. DNK sekvenciranje za 1638 bp (B2) i 429 bp (B1) je izvrseno. Analiza sekvence je ukazala da ove dve PCR velicine amplikona su dva tipa gena koji kodiraju beta-defensine i veoma se blizu jedna drugom. Na osnovu razlicitosti sekvenci (B1 i B2) sa defensin genima predstavljenim u GenBank, konstruisano je filogeneticko stablo. Novi gen (B1) pripada porodici beta-defensin gena i otkriven je po prvi put I povezan sa niskom proizvodnjom mleka u populaciji goveda.