Polymorphism in porcine somatotropin cDNA sequences

Restriction fragment length polymorphisms at the growth hormone gene in pigs

Pigs from four Danish and two Swedish populations were examined for restriction fragment length polymorphism (RFLP) at the growth hormone (GH) gene. Polymorphism was detected with the restriction enzymes DraI and TaqI. A comparison of the Danish populations showed significant differences among their allelic frequencies.

Growth hormone gene polymorphisms and growth performance traits in Duroc, Landrace and Tao-Yuan pigs

This study investigated the restriction fragment length polymorphism (RFLP) of the porcine growth hormone (pGH) gene in Duroc, Landrace, and Tao-Yuan pigs and its effects on growth performance and levels of plasma growth hormone in peripheral circulation. Genomic DNA extracted from 81 Tao-Yuan, 60 Landrace and 48 Duroc pigs were subjected to Southern blot hybridization with a pGH cDNA probe. Polymorphism was detected with the restriction enzymes TaqI and DraI. A comparison of these three breeds showed significant differences in allelic frequencies. Blood samples for radioimmunoassay (RIA) of GH were collected biweekly during the experimental period from pigs 12 to 40 weeks of age. Tao-Yuan pigs showed a mean plasma GH level (2.51 +/- 1.23 ng/mL) that was much lower than that of the Landrace (3.80 +/- 1.52 ng/mL) and Duroc (4.20 +/- 1.03 ng/mL) pigs (P < 0.05). Moreover, the Tao-Yuan pigs also showed poorer growth performance than the Landrace and the Duroc pigs both in the daily weight gain (0.37 +/- 0.06 vs. 0.67 +/- 0.05 and 0.70 +/- 0.05 kg/day, P < 0.01) and feed efficiency (3.12 +/- 0.28 vs. 2.60 +/- 0.14 and 2.52 +/- 0.12, P < 0.05). These results suggest that the growth performance trait in these pigs is highly correlated with their growth hormone genotype.

The effect of phage T7 lysozyme on the production of biologically active porcine somatotropin in Escherichia coli from a gene transcribed by T7 RNA polymerase

We have analyzed the inducible synthesis of recombinant porcine somatotropin (rPST) from the phage T7 gene 10 promotor on the vector pET3a [Rosenberg et al., Gene 56 (1987) 125-135]. Low-level synthesis of phage T7 lysozyme is crucial for high-level synthesis (40%) of rPST, which is greatly reduced if T7 lysozyme synthesis is absent or too high. The synthesis of rPST mRNA is optimized in those constructs coding for low levels of T7 lysozyme, with a reduction in mRNA levels in constructs coding for higher levels of T7 lysozyme or no lysozyme. The rPST can be readily purified following a single chromatographic step and is biologically active as determined by the tibia test following administration to hypophysectomized rats.