Polimorfizam gena hormona rasta (GH) i njegova povezanost sa svojstvima rasta u ovaca pasmine Kilakarsal

The goal of this study was to investigate the single nucleotide polymorphism of the growth hormone gene and its association with growth traits in the Kilakarsal breed of sheep. Polymerase Chain Reaction – Restriction Fragment Length Polymorphism (PCR-RFLP) of the growth hormone gene (422 bp) with HaeIII restriction enzyme revealed an A781G transition mutation at the exon 2 and the existence of two genotypes, viz., AA (366 bp and 56 bp) and AB (422 bp, 366 bp and 56 bp). The occurrence of the B allele is due to the A781G transition in the exon 2 of the growth hormone gene, which causes an amino acid change from Serine to Glycine. The genotype BB was absent in the Kilakarsal sheep population. The absence of the BB genotype at the A781G locus of the growth hormone gene in the Kilakarsal sheep population indicates that the natural selection process might be acting against this particular genotype through reduced viability or early embryonic death. Further, the statistical analysis revealed the significantly higher yearling weight of the AB than the AA genotype (P=0.038), and an appreciable difference of 1.40 kg in 9-month weight. The highly significant (P<0.001) Chi-square value (29.94) showed that the population is not the under Hardy-Weinberg equilibrium. This indicates that molecular markers associated with body weight should be explored for their use in marker assisted selection in Kilakarsal population.Cilj ovog rada bio je istražiti polimorfizam pojedinačnog nukleotida gena hormona rasta i njegovu povezanost sa svojstvima rasta u ovaca pasmine Kilakarsal. Lančana reakcija polimerazom – polimorfizam duljine restrikcijskih fragmenata (PCR-RFLP) gena hormona rasta (422 bp) s restrikcijskim enzimom HaeIII otkrila je A781G mutaciju na eksonu 2 i postojanje dvaju genotipova: AA (366 bp i 56 bp) i AB (422 bp, 366 bp i 56 bp). Navedena mutacija, osim što uzrokuje pojavu alela B, uzrokuje i promjenu aminokiseline serin u aminokiselinu glicin. Genotip BB u istražene pasmine ovaca nije pronađen. Odsutnost genotipa BB na lokusu A781G gena hormona rasta u ovaca pasmine Kilakarsal upućuje na to da prirodni process selekcije može djelovati protiv tog određenog genotipa putem smanjene sposobnosti preživljavanja ili rane embrionalne smrti. Nadalje, statistička je analiza otkrila znakovito veću tjelesnu masu genotipa AB od genotipa AA (P=0,038) i znatnu razliku od 1,40 kg u 9-mjesečnoj tjelesnoj masi istraženih ovaca. Visoko znakovita vrijednost (P<0,001) hi-kvadratnog testa (29,94) pokazala je da ova populacija ovaca ne odstupa od Hardy-Weinbergova zakona ravnoteže. To nas upućuje na zaključak da treba istražiti molekularne biljege povezane s tjelesnom masom ovaca pasmine Kilakarsal radi njihove primjene u selekciji potpomognutoj biljezima