Crow M T, Olson P S, Stockdale F E
J Cell Biol. 1983 Mar;96(3):736-44. doi: 10.1083/jcb.96.3.736.
Monoclonal antibodies to adult chicken myosin light chains were generated and used to quantitate the types of myosin light-chain (MLC) isoforms expressed during development of the pectoralis major (PM), anterior latissimus dorsi (ALD), and medial adductor (MA) muscles of the chicken. These are muscles which, in the adult, are composed predominantly of fast, slow, and a mixture of fiber types, respectively. Three distinct phases of MLC expression characterized the development of the PM and MA muscles. The first identifiable pase occurred during the period of 5-7 d of incubation in ovo. Extracts of muscles from the pectoral region (which included the presumptive PM muscle) contained only fast MLC isoforms. This period of exclusive fast light-chain synthesis was followed by a phase (8- 12 d of incubation in ovo) in which coexpression of both fast and slow MLC isoforms was apparent in both PM and MA muscles. During the period, the composition of both fast and slow MLC isoforms in the PM and MA muscles was identical. Beginning at day 12 in ovo, the ALD was also subjected to immunochemical analyses. The proportion of fast and slow MLCs in this muscle at day 12 was similar to that present in the other muscles studied. The third development phase of MLC expression began at approximately 12 d of incubation in ovo and encompassed the transition in MLC composition to the isoform patterns incubation in ovo and encompassed the transition in MLC composition to the isoform patterns typical of adult muscle. During this period, the relative proportion of slow MLC rose in both the MA and ALD and fell in the PM. By day 16, the third fast light chain, LC(3f), was apparent in extracts of both the PM and MA. These results show that there is a developmental progression in the expression of MLC in the two avian muscles studied from day 5 in ovo; first, only fast MLCs are accumulated, then both fast and slow MLC isoforms are expressed. Only during the latter third of development in ovo is the final MLC isoform pattern characteristic of a particular muscle type expressed.
制备了针对成年鸡肌球蛋白轻链的单克隆抗体，并用于定量鸡胸大肌（PM）、背阔肌前部（ALD）和内收肌（MA）发育过程中表达的肌球蛋白轻链（MLC）同工型类型。这些肌肉在成年时分别主要由快肌纤维、慢肌纤维和混合纤维类型组成。MLC表达的三个不同阶段表征了PM和MA肌肉的发育过程。第一个可识别阶段发生在鸡胚孵化5至7天期间。胸肌区域（包括推测的PM肌肉）的肌肉提取物仅含有快MLC同工型。在这个仅合成快轻链的时期之后，进入一个阶段（鸡胚孵化8至12天），在此阶段，PM和MA肌肉中快和慢MLC同工型的共表达明显。在此期间，PM和MA肌肉中快和慢MLC同工型的组成相同。从鸡胚孵化第12天开始，也对ALD进行免疫化学分析。该肌肉在第12天时快和慢MLC的比例与其他研究肌肉中的比例相似。MLC表达的第三个发育阶段大约从鸡胚孵化第12天开始，包括MLC组成向成年肌肉典型同工型模式的转变。在此期间，MA和ALD中慢MLC的相对比例上升，而PM中则下降。到第16天，PM和MA的提取物中都出现了第三条快轻链LC(3f)。这些结果表明，在所研究的两种禽类肌肉中，从鸡胚孵化第5天开始，MLC的表达存在发育进程；首先，只积累快MLC，然后快和慢MLC同工型都表达。只有在鸡胚发育的后三分之一时间才表达特定肌肉类型特有的最终MLC同工型模式。
