ACTIVITY AND CONTENT OF ISOZYMES OF ASPARTATE AMINOTRANSFERASE IN CONNECTION WITH THE SURVIVAL OF BULL SPERMATOZOA

Abstract

The activity and content of aspartate aminotransferase (AST) isoforms in bovine ejaculates due to sperm survival were studied.
 Ejaculates of bulls of the Ukrainian black-spotted dairy breed (n = 22) were selected for research. In freshly obtained and incubated semen the activity and isozymes of AST was studied in connection with spermatozoa survival at a temperature of 2-4 ° C (on the first, second, third and fourth days) until the cessation of rectilinear translational movement.
 AST activity depended on the duration of sperm survival. When survival was more than 100 hours - AST activity was the highest - 65.2 ± 1.7 nmol / min × mg of protein. When survival was lower - up to 100 hours, enzymatic activity lower by 26.8% (P <0.001). Two enzymes of the enzyme (AST1 and AST2) were found in the semen of the fetuses, which differ in electrophoretic mobility and intensity of staining in 7.5% polyacrylamide gel.
 The established correlation with sperm survival time has a strong straight line for AST1 (η2АSТ1 = 0.88) and inverse - for AST2 (η2АSТ2 = 0.87) isozymes. During sperm incubation, the ratio of AST isozymes changes - the content of AST1 increases and decreases - AST2. The correlation ratio for sperm survival for enzyme activity and isozymes is up to 100 hours, respectively. - η2АSТ = 0.83; η2АSТ1 = 0.68 and η2АSТ2= 0.69 and more than 100 hours - η2АSТ = 0.75; η2АSТ1= 0.92 and η2АSТ2= 0.69.
 Therefore, ejaculates of bulls with reduced sperm survival are characterized by lower AST activity and, accordingly, the speed of the amino acid transamination process. Increased supply of substrates from the cytosol in the mitochondria of germ cells ensures high survival of sperm. Changes in the activity and content of AST isozymes, which characterize the energy supply of germ cells, can serve as a criterion for the physiological quality of sperm of freshly obtained sperm.