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首页> 外文期刊>Journal of Comparative Physiology, B. Biochemical, Systemic, and Environmental Physiology >Links between muscle phenotype and life history: differentiation of myosin heavy chain composition and muscle biochemistry in precocial and altricial pinniped pups
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Links between muscle phenotype and life history: differentiation of myosin heavy chain composition and muscle biochemistry in precocial and altricial pinniped pups

机译：肌肉表型和寿命史之间的联系：肌球蛋白重链组成的分化和赤裸裸的小幼虫肌肉生物化学

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摘要

In marine mammals, muscular development has been identified as a rate-limiting factor in achieving adult dive capacities. This study investigates the rate that myosin heavy chain (MHC) composition matures in a postural and locomotor skeletal muscle for four pinniped species with different lactation lengths: hooded seals, Cystophora cristata; harp seals, Pagophilus groenlandicus; northern fur seals, Callorhinus ursinus, and Steller sea lions, Eumetopias jubatus. The ontogeny of MHC isoform expression was compared with developmental rates of myoglobin concentrations, and aerobic (citrate synthase, beta-hydroxyacyl-CoA dehydrogenase) and anaerobic (lactate dehydrogenase) enzyme activities. Within taxonomic families, species with shorter lactation periods had more mature muscles biochemically at birth, and fiber types differentiated earlier during ontogeny (Phocidae: hooded > harp seals, Otariidae: northern fur seals > Steller sea lions). Northern fur seal neonates had the most phenotypically-mature muscles in this study, with no immature MHC isoforms. The relationship between muscle biochemistry and MHC composition became more pronounced with age, and developed to reflect swimming mode and activity levels. In adults, phocids had more slow-twitch oxidative protein in their primary locomotor muscle, the Longissimus dorsi (LD), than otariids which likely reflects oxygen-sparing strategies for the phocids' longer dives. Conversely, northern fur seal muscles had higher proportions of fast-twitch MHCs in the Pectoralis and LD, likely indicative of this species' smaller size and higher mass-specific metabolic rates. Thus, muscle phenotype is linked with species life history, and a mismatch between muscle biochemistry and MHC composition at weaning has important implications for the first year of independent foraging in pinniped pups.
机译：在海洋哺乳动物中，肌肉发育已被确定为实现成人潜水能力的速率限制因素。本研究调查了肌球蛋白重链（MHC）组成在姿态和运动骨骼肌中的速率，用于不同哺乳期的四个尖刺物种：连帽密封件，胱硫氏菌嵴;竖琴海豹，野生植物檐口;北部毛皮海豹，乌利辛斯，和斯特勒海狮，烟草湖朱谟。将MHC同种型表达的组织发生与肌球蛋白浓度的发育速率进行比较，以及有氧（柠檬酸合酶，羟基苯基-CoA脱氢酶）和厌氧（乳酸脱氢酶）酶活性。在分类家庭中，哺乳期较短的物种在出生时具有更高的成熟肌肉，并且在脑发生过程中早期分化的纤维类型（Phocidae：Haimed> Harp Seals，Otariidae：北毛皮海豹> Steller Sea Lions）。北毛皮海豹新生儿在本研究中具有最表型成熟的肌肉，没有未成熟的MHC同种型。肌肉生物化学和MHC组成之间的关系变得更加明显，并且发展成为反映游泳模式和活动水平。在成人中，Phocids在其主要运动肌肉中具有更缓慢的抽搐氧化蛋白，而不是Otariid，这可能反映了Phocids较长潜水的氧气制剂。相反，北部毛皮密封肌在胸壁和LD中具有更高的快速抽搐MHC，可能是该物种的较小尺寸和更高的质量特异性代谢率。因此，肌肉表型与物种寿命历史相关联，断奶肌肉生物化学和MHC组合物之间的错配在钉子幼崽中的独立觅食的第一年具有重要意义。

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