Rosser B W, Wick M, Waldbillig D M, Wright D J, Farrar C M, Bandman E
University of Saskatchewan, College of Medicine, Department of Anatomy and Cell Biology, Saskatoon, Canada.
Int J Dev Biol. 1998 Jul;42(5):653-61.
The pectoralis muscle of birds provides virtually all the power for the downstroke of the wing during flight. In adults it consists almost entirely of FOG (fast-twitch oxidative-glycolytic) and/or FG (fast-twitch glycolytic) fiber types. The aims of this study are to contrast MyHC (myosin heavy chain) transitions occurring within avian FG and FOG fibers during development, and to test the hypothesis that the pectoralis matures before the acquisition of flight. Pectoralis was obtained from pigeons (Columba livia) aged from 13 days in ovo to adult. Monoclonal antibodies generated against chicken MyHC isoforms were used with Western blots and immunocytochemistry. FG and FOG fibers were differentiated using a histochemical method demonstrating NADH (nicotinamide adenine dinucleotide), and "lesser fiber diameters" were quantified. Western blots confirm that the antibodies label pigeon MyHCs. A small number of the fibers are slow type in ovo, but these are quickly restricted in distribution and lost after hatching. In ovo fast-twitch fibers contain a ventricular isoform, and at least two embryonic-neonatal forms (designated E-N103 and E-N165). One week after hatching, fast-twitch fibers can be distinguished by NADH as FG or FOG. At fledging, four weeks after hatching, FG and FOG fibers are smaller than in older birds and E-N103 and E-N165 persist in both fibertypes. E-N103 wanes in all fibers shortly after fledging. E-N165 gradually disappears from FG fibers. Thus, despite pigeons being at adult body mass at fledging, their pectoralis is not fully mature.
鸟类的胸肌几乎为飞行过程中翅膀向下扇动提供了所有动力。在成年鸟类中，胸肌几乎完全由快缩氧化糖酵解（FOG）和/或快缩糖酵解（FG）纤维类型组成。本研究的目的是对比鸟类FG和FOG纤维在发育过程中发生的肌球蛋白重链（MyHC）转变，并检验胸肌在获得飞行能力之前就已成熟这一假设。从鸽蛋孵化13天到成年的鸽子（家鸽）获取胸肌。使用针对鸡MyHC亚型产生的单克隆抗体进行蛋白质免疫印迹和免疫细胞化学实验。采用显示烟酰胺腺嘌呤二核苷酸（NADH）的组织化学方法区分FG和FOG纤维，并对“较小纤维直径”进行量化。蛋白质免疫印迹证实这些抗体能够标记鸽子的MyHC。在鸽蛋中少量纤维为慢肌纤维类型，但这些纤维的分布很快受到限制并在孵化后消失。鸽蛋中的快缩纤维含有一种心室亚型以及至少两种胚胎 - 新生儿型（命名为E - N103和E - N165）。孵化一周后，通过NADH可将快缩纤维区分为FG或FOG纤维。在孵化四周后的羽翼丰满期，FG和FOG纤维比成年鸟类的小，并且E - N103和E - N165在两种纤维类型中均持续存在。羽翼丰满后不久，E - N103在所有纤维中逐渐减少。E - N165在FG纤维中逐渐消失。因此，尽管鸽子在羽翼丰满时已达到成年体重，但其胸肌并未完全成熟。
