Caracterização de polimorfismos na região do promotor do gene da paraoxonase 1 (PON1) e seu efeito sobre a atividade enzimática em vacas leiteiras

Abstract

Molecular markers, increasingly are being used in breeding programs of dairy cattle, including several production and health characteristics. On the other hand, the reduced activity of paraoxonase (PON1) in the circulation of animals is associated with increased occurrence of diseases in these individuals, there is little information regarding the influence of the PON1 gene in this process. The aim of this study was to characterize the occurrence of polymorphisms in the promoter region of the PON1 gene and to evaluate its relationship with serum PON1 activity in peripartum dairy Holstein cows. For that blood was collected from 28 Holstein cows for analysis of serum activity of paraoxonase (PON1). The sampling was performed on days -21, -7, 0, 3, 6, 9 and 23 (day 0 = day of calving). DNA extraction was performed in circulating leukocytes and PCR of these samples was performed, targeting the amplification of a DNA fragment containing 828 bp in the PON1 promoter. After agarose gel electrophoresis, the samples were purified and sequenced to identify the polymorphisms. Six SNPs were found in the promoter of the PON1 gene, located at positions -22, -105, -221, -392, -611 and -676. From these, SNPs -105, -221 and -611 were associated with serum PON1 activity during the study period (p < 0.05), whereas the PON1-105(AA), PON1-221(AA) and PON1 -611(CC) genotypes had higher levels of PON1 (p < 0.05). Moreover, SNPs -105 and -221 had differences in the levels of PON1 already during the prepartum period (p < 0.05). In conclusion, 6 SNPs were identified in the promoter of the PON1 gene, three of which are associated with the activity of the enzyme.