Changes in RNA Species during Differentiation of Fiber Types in Skeletal Muscle

Fetuses of Lean and Obese Swine in Late Gestation: Body Composition, Plasma Hormones and Muscle Development

“…Limb muscle groups, represented in this study by the semitendinosus muscle, develop rapidly and early in the fetus, probably because they are crucial for the locomotion needed to suckle after birth (Hakkarainen, 1975). In contrast, the longissimus muscle develops far less rapidly in the fetus, with greater development in the early postnatal ages (Swatland, 1973;Tsai et al, 1973). Our RNA, DNA and protein data support this muscle growth pattern in that concentrations, protein/DNA, and RNA/DNA generally were higher in semitendinosus than longissimus muscles during 30-d period studied.…”

“…All RNA/DNA values in this study were lower than found in postnatal pigs. This finding was expected because Tsai et al (1973) and Hakkarainen (1975) both found postnatal patterns of increasing RNA and decreasing DNA concentrations resulting in increasing postnatal RNA/DNA. As in the Buhlinger et al (1978) study, but unlike the Ezekwe and Martin (1975) study, the lean and obese pigs in the present study showed no difference in RNA/DNA ratios, indicating no difference in capacity to synthesize protein per nucleus.…”

Assay of factors affecting rate of protein biosynthesis in bovine and porcine skeletal muscle

“…On the other hand, the value of 0.74 mg RNA/100 g of muscle, fresh weight, found for RNA concentration of porcine skeletal muscle in the present study is lower than the values of 1.40 mg RNA/100 g of muscle, fresh weight, found by both Tsai et al, (1973) and Harbison et al, (1976), for porcine skeletal muscle (Table 11). These analysis were all done on animals of similar live weights (Table 11).…”

“…These analysis were all done on animals of similar live weights (Table 11). Although Tsai et al, (1973) and Harbison et al, (1976), used the orcinol procedure for measuring RNA concentration, the orcinol procedure, as indicated in the preceding paragraph, gives identical results for muscle RNA concentration as the modified Schmidt-Tannhauser procedure used in the present study. Consequently, the difference in RNA concentrations reported in the present study and in the studies of Tsai et al, (1973) and Harbison et al, (19 76) may be due to the difference in RNA concentration between the lonqissimus dorsi and the semitendinosus muscles used in these studies (Table 11).…”

“…The decline in growth rate during senescence results from a decline in protein synthesis, occurring largely because both activity and concentration of polysomal RNA and RNA in the pH5 enzyme fraction decreases (Srivastava, 1969a, b). The effect of animal age on muscle RNA content and rate of muscle protein biosynthesis in mice (Millward et al, 1975;Srivastava and Chaudhary, 1969) and on muscle RNA content in pigs (Tsai et al, 1973) has been studied. Both muscle RNA content and rate of protein synthesis decreased very rapidly as the animals reached maturity and remained constant after that period.…”