The study of candidate genes, based on physiological effects, is an important tool to identify genes to be used in marker-assisted selection programs. In this study, a group of halothane gene-free, non-castrated, male Landrace pigs was used to study the association between polymorphisms in the PIT1 (n = 218), GH (n = 213) and GHRH (n = 206) genes and fat thickness, average daily gain, and the EPD (expected progeny difference) for fat thickness, average daily gain, and litter size. These genes are potential candidate markers because of their important physiological effects. The pigs were genotyped by PCR-RFLP, and the statistical model used to analyze the association between genotypes and the traits measured included genotypes as a fixed effect and age and weight as covariates. PIT1 polymorphisms were associated with fat thickness (P = 0.0019), EPD for average daily gain (P = 0.0001) and EPD for fat thickness (P = 0.0001), whereas GH polymorphisms were associated with fat thickness (P = 0.0326) and average daily gain (P = 0.0127), and GHRH polymorphisms were associated with the average daily gain (P = 0.0001) and EPD for fat thickness (P = 0.0004). These results confirmed the potential usefulness of these genes in marker-assisted selection programs for pig breeding.
Subjects were required to track a target consisting of two vertical bars moving with either a constant or a sinusoidally modulated speed an osciloscope scren with a joystick-controlled light-spot.Either target size or velocity of the target movement(velocity quided tasks), varied throughout different tasks determined by subject's performance.The target's initial movement period was either 2 or 3 seconds.The following parameters were studied: time on-terget intervals, time off-target intervals, number of tracking errors, heart rate and tracking error incidence over the cardiac cycle.Time on-target intervals were longer for the velocity quided tasks then for the size quided ones.The same was true for time off-terget intervals.Values for both types of intervals decreased gradually over the fixed sequence of tasks for velocity but not for size quided tasks.Heart rate was higher in the size quided task.Tracking error incidence did not depend on the phase of cardiac cycle.
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