Chanoine C, Guyot-Lenfant M, Saadi A, Perasso F, Salles-Mourlan A M, Gallien C L
Laboratoire de Biologie du Développement, Université René Descartes, Paris, France.
Int J Dev Biol. 1990 Mar;34(1):163-70.
Electrophoretic analysis in non-dissociating conditions reveals three types of myosin in adult urodelan amphibian skeletal muscles: 3 isoforms of fast myosin (FM), one isoform of intermediate myosin (IM) and one or two isoforms of slow myosin (SM). Each type is characterized by a specific heavy chain HCf (FM), HCi (IM) and HCs (SM), respectively. In all urodelan species, as in mammals, fast isomyosins associate HCf and the three fast light chains LC1f, LC2f, and LC3f. In most urodelan species the intermediate myosin contains LC1f and LC2f and can be considered as an homodimer of the alkali LC1f. However, in Euproctus asper, IM is characterized by the association of both slow and fast LC with HCi. Slow myosin is a hybrid molecule associating HCs with slow and fast LC. During metamorphosis, a myosin isoenzymic transition occurs consisting in the replacement of three larval myosins (LM) characterized by a specific heavy chain (HCI), by the adult isomyosins with lower electrophoretic mobilities. At the same time there is a change in the ATPase myofibrillar pattern, with the larval fiber types being replaced by adult fibers of types I, IIA and IIB. In the neotenic and perennibranchiate species, which do not undergo spontaneous metamorphosis, sexually mature larval animals present a change in the myosin isoenzymic profile, but no complete transition. The coexistence of larval and adult isomyosins and the persistence of transitional fibers of type IIC in the skeletal muscle are demonstrated. Experimental hypo- and hyperthyroidism indicate that thyroid hormone stimulates the regression of the larval isomyosins, possibly through indirect pathways. In contrast, the appearance and the persistence of the adult isomyosins seem to be independent of thyroid hormone. Thus, the control of the isoenzymic transition in the skeletal muscle of urodelan amphibians appears to imply indirect mechanisms, operating differently on each of the two phases of the complete transition.
在非解离条件下的电泳分析显示，成年有尾两栖动物骨骼肌中有三种类型的肌球蛋白：三种快速肌球蛋白（FM）同工型、一种中间肌球蛋白（IM）同工型以及一种或两种慢速肌球蛋白（SM）同工型。每种类型分别由特定的重链HCf（FM）、HCi（IM）和HCs（SM）表征。在所有有尾两栖动物物种中，与哺乳动物一样，快速同型肌球蛋白由HCf与三条快速轻链LC1f、LC2f和LC3f结合而成。在大多数有尾两栖动物物种中，中间肌球蛋白含有LC1f和LC2f，可被视为碱性LC1f的同型二聚体。然而，在粗糙真螈中，IM的特征是慢速和快速轻链均与HCi结合。慢速肌球蛋白是一种将HCs与慢速和快速轻链结合的杂合分子。在变态过程中，会发生肌球蛋白同工酶转变，即由具有特定重链（HCI）的三种幼虫肌球蛋白（LM）被电泳迁移率较低的成年同型肌球蛋白所取代。同时，肌原纤维ATP酶模式也会发生变化，幼虫纤维类型被I型、IIA型和IIB型成年纤维所取代。在不经历自发变态的幼态持续和终生鳃呼吸物种中，性成熟的幼虫动物肌球蛋白同工酶谱会发生变化，但没有完全转变。骨骼肌中幼虫和成年同型肌球蛋白共存以及IIC型过渡纤维持续存在得到了证实。实验性甲状腺功能减退和亢进表明，甲状腺激素可能通过间接途径刺激幼虫同型肌球蛋白的消退。相比之下，成年同型肌球蛋白的出现和持续似乎与甲状腺激素无关。因此，有尾两栖动物骨骼肌同工酶转变的控制似乎涉及间接机制，在完全转变的两个阶段中对每个阶段的作用方式不同。
