Myosin Isoform Fiber Type and Fiber Size in the Tail of the Virginia Opossum (Didelphis virginiana)
Myosin Isoform Fiber Type and Fiber Size in the Tail of the Virginia Opossum (Didelphis virginiana)
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DOI：
10.1002/ar.22614
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发表时间：
2013-01-01
影响因子：
2
通讯作者：
Butcher, M. T.
中科院分区：
文献类型：
--
作者：
Hazimihalis, P. J.;Gorvet, M. A.;Butcher, M. T.
肌纤维类型是四肢肌肉的一个很好的研究属性，然而，很少了解肌球蛋白重链（MHC）异构体在哺乳动物尾部肌肉的表达。Didelphid有袋类动物是一个有趣的谱系，因为所有物种都有可伸缩的尾巴，但根据它们的树栖或陆生运动习惯，显示出一系列的尾巴功能。在同源性的差异表明，MHC亚型纤维类型也可能是不同的，在陆地负鼠可能有一个大的分布的氧化纤维的对象携带任务，而不是更快，糖酵解纤维类型预期在哺乳动物的长尾。为了验证这一假设，MHC亚型纤维类型和它们的区域分布（近端/过渡/远端）的弗吉尼亚负鼠（Didelphis virginiana）的尾巴。肌球蛋白ATP酶组织化学，免疫组化和SDS-PAGE相结合的纤维类型进行了确定。结果表明在尾部的每个区域中快速MHC-2A和-2X同种型占优势。通过SDS-PAGE分析证实了除了慢MHC-1同种型之外，两种快同种型的存在。尾部的总体MHC同种型纤维类型分布为：25%MHC-1、71%MHC-2A/X杂合体和4%MHC-1/2A杂合体。发现氧化性MHC-2A/X同种型纤维的横截面相对于缓慢的氧化性MHC-1和MHC-1/2A混合纤维较大。大比例的快速MHC-2A/X杂交纤维可能是暗示的MHC亚型分布（快到慢的纤维类型）在负鼠的尾部肌肉组织的进化过渡，主要是地面运动的习惯和适应性尾功能。Anat Rec，296：96-107，2013. (C)2012 Wiley Periodicals，Inc.
Muscle fiber type is a well studied property in limb muscles, however, much less is understood about myosin heavy chain (MHC) isoform expression in caudal muscles of mammalian tails. Didelphid marsupials are an interesting lineage in this context as all species have prehensile tails, but show a range of tail-function depending on either their arboreal or terrestrial locomotor habits. Differences in prehensility suggest that MHC isoform fiber types may also be different, in that terrestrial opossums may have a large distribution of oxidative fibers for object carrying tasks instead of faster, glycolytic fiber types expected in mammals with long tails. To test this hypothesis, MHC isoform fiber type and their regional distribution (proximal/transitional/distal) were determined in the tail of the Virginia opossum (Didelphis virginiana). Fiber types were determined by a combination of myosin-ATPase histochemistry, immunohistochemistry, and SDS-PAGE. Results indicate a predominance of the fast MHC-2A and -2X isoforms in each region of the tail. The presence of two fast isoforms, in addition to the slow MHC-1 isoform, was confirmed by SDS-PAGE analysis. The overall MHC isoform fiber type distribution for the tail was: 25% MHC-1, 71% MHC-2A/X hybrid, and 4% MHC-1/2A hybrid. Oxidative MHC-2A/X isoform fibers were found to be relatively large in cross-section compared to slow, oxidative MHC-1 and MHC-1/2A hybrid fibers. A large percentage of fast MHC-2A/X hybrids fibers may be suggestive of an evolutionary transition in MHC isoform distribution (fast-to-slow fiber type) in the tail musculature of an opossum with primarily a terrestrial locomotor habit and adaptive tail-function. Anat Rec, 296: 96-107, 2013. (C) 2012 Wiley Periodicals, Inc.