生活在圣诞岛（位于爪哇岛南部印度洋东部的一座岛屿）上的红螃蟹在度过了几个月悠闲的时光后，便会开始一场漫长的马拉松比赛。
在5到6天的时间里，这些螃蟹会从它们位于雨林的家中迁徙到海里进行交配，其全程约为5公里。
那么它们究竟是如何在这么短的时间里变得如此敏捷呢？为了找到问题的答案，研究人员来到圣诞岛上，并在红螃蟹的迁徙期以及6个月后——这时它们会不慌不忙地返回雨林——采集了它们的腿部肌肉。
通过对这两种样本进行遗传学分析，研究人员发现两者在14种基因的表达上存在巨大差异。通过改变自身产生能量的方式，这些变化帮助红螃蟹的腿部肌肉为漫长而艰巨的旅程作好准备。
在那些不需要长途跋涉的红螃蟹中，基因活动使得肌肉纤维能够从事于无氧代谢——这种模式不需要氧的参与并适合于短期运动。另一方面，在那些迁徙去海边的红螃蟹中，基因的表达促进了有氧代谢——这种模式需要氧的参与并最适合于高耐力运动。研究人员表示，为了应付比赛，迄今为止，人类依然不得不通过大运动量的训练来提高成绩。
研究人员在5月号的《实验生物学杂志》网络版上报告了这一研究成果。（生 物 谷Bioon.com）
生物谷推荐原文出处：
Journal of Experimental Biology doi: 10.1242/jeb.033829 This Article
Migration-related changes in gene expression in leg muscle of the Christmas Island red crab Gecarcoidea natalis: seasonal preparation for long-distance walking
Ute Postel, Fiona Thompson, Gary Barker, Mark Viney* and Steve Morris
School of Biological Sciences, University of Bristol, Woodland Road, Bristol, BS8 1UG, UK
During their annual breeding migration the Christmas Island land crab Gecarcoidea natalis sustains locomotion aerobically for up to 12 h per day compared with just 10 min during the dry season when their muscles quickly become anaerobic. A seasonal transition to an endurance-muscle phenotype would thus seem essential for migrating crabs. The current study employed a gene discovery approach comparing two expressed sequence tag (EST) libraries, one each for leg muscle from dry (non-migrating) and wet season (migrating) crabs. The 14 most abundant transcripts differed in their representation between the two libraries. The abundances of transcripts of genes predicted to code for different proteins forming contractile muscle components, including actin, troponin and tropomyosin, were significantly different between seasons and thus between physiological states. The shift in the isoform composition of the contractile elements provided evidence for a switch from slow phasic (S1) to slow tonic (S2) fatigue-resistant muscle fibres. A tropomyosin (tm) transcript aligned with a tm isoform of lobster (tmS2), and semi-quantitative RT-PCR confirmed this isoform to be more abundant in the migrating crab muscle. Two LIM protein coding genes, a paxillin-like transcript (pax) and a muscle LIM protein (mlp), were relatively up-regulated in muscle of wet season crabs. These proteins have a fundamental role in muscle development and reconstruction, and their comparative up-regulation is consistent with a remodelling of leg muscle for migration in the wet season. Such a transition would result in an increased representation of aerobic endurance-type fibres concomitant with the greater aerobic exercise capacity of the migrating red crabs.
