Gondret F, Lefaucheur L, D'Albis A, Bonneau M
Station de Recherches Cunicoles, INRA, BP 27, Castanet-Tolosan, France.
J Muscle Res Cell Motil. 1996 Dec;17(6):657-67. doi: 10.1007/BF00154060.
Four rabbit muscles (i.e. semimembranosus proprius, psoas major, biceps femoris and longissimus lumborum), differing in their fibre type composition in the adult, were investigated during postnatal development. Muscle samples were taken at 1, 7, 14, 21, 28, 35, 49 and 77 days of age. Complementary techniques were used to characterize myosin heavy chain (MHC) isoform transitions, i.e. SDS-PAGE, immunocytochemistry and conventional histochemistry. Good accordance was found between electrophoretic and immunocytochemical techniques. Our results show that rabbit muscles were phenotypically immature at birth. At 1 day of age, perinatal isoform represented 70-90% of the total isoform content of the muscles. Two generations of myofibres could be observed on the basis of their morphology and reaction to specific antibodies. In all muscles, primary fibres expressed slow MHC. In contrast, secondary generation of fibres never expressed slow MHC in future fast muscles, while half of them expressed slow MHC in the future slow-twitch muscle, the semimembranosus proprius. During the postnatal period, all muscles displayed a transition from embryonic to perinatal MHC isoforms, followed by a transition from perinatal to adult MHC isoforms. These transitions occured mainly during the first postnatal month. The embryonic isoform was no longer expressed after 14 days, except in longissimus where it disappeared after 28 days. On the contrary, large differences were found in the timing of disappearance of the perinatal isoform between the four muscles. The perinatal isoform disappeared between 28 and 35 days in semimembranosus proprius and 35 and 49 days in psoas and biceps femoris. Interestingly, the perinatal isoform was still present in 6% of the fibres in longissimus at 77 days, the commercial slaughter age, denoting a great delay in the maturation. Fate of each generation of fibres differed between muscles.
对四只成年后纤维类型组成不同的兔肌肉（即半膜肌、腰大肌、股二头肌和腰最长肌）在出生后的发育过程中进行了研究。在1、7、14、21、28、35、49和77日龄时采集肌肉样本。使用互补技术来表征肌球蛋白重链（MHC）同工型的转变，即SDS - PAGE、免疫细胞化学和传统组织化学。电泳技术和免疫细胞化学技术之间发现了良好的一致性。我们的结果表明，兔肌肉在出生时表型不成熟。在1日龄时，围产期同工型占肌肉总同工型含量的70 - 90%。根据其形态和对特定抗体的反应，可以观察到两代肌纤维。在所有肌肉中，初级纤维表达慢MHC。相反，在未来的快肌中，第二代纤维从不表达慢MHC，而在未来的慢肌半膜肌中，其中一半表达慢MHC。在出生后的时期，所有肌肉都表现出从胚胎型MHC同工型向围产期MHC同工型的转变，随后是从围产期MHC同工型向成年MHC同工型的转变。这些转变主要发生在出生后的第一个月。胚胎型同工型在14天后不再表达，除了腰最长肌，它在28天后消失。相反，在这四块肌肉中，围产期同工型消失的时间存在很大差异。围产期同工型在半膜肌中在28至35天之间消失，在腰大肌和股二头肌中在35至49天之间消失。有趣的是，在商业屠宰年龄77天时，腰最长肌中仍有6%的纤维存在围产期同工型，这表明其成熟过程有很大延迟。不同肌肉中每一代纤维的命运各不相同。
