Hyde D, Pearson T, Qari S, Bowler K
Department of Biological and Biomedical Sciences, University of Durham, South Road, Durham, DH1 3LE, UK,
J Comp Physiol B. 2015 Aug;185(6):629-36. doi: 10.1007/s00360-015-0912-x. Epub 2015 May 21.
The aim of this study was to determine seasonal differences in the temperature dependence of neuromuscular parameters of the dactylopodite walking leg closer muscle in two species of freshly caught summer and winter decapod crabs. The relatively stenothermal Cancer pagurus (Cp) and eurythermal Carcinus maenas (Cm) muscle resting potential (RP) hyperpolarised significantly with increasing experimental temperature. The muscle RP in Cm was seasonally dependent at acute temperatures above 20 °C whereas in Cp no seasonal effect was observed. The latent period of the muscle excitatory junction potential (EJP) following tonic motor nerve stimulation was significantly longer in winter-caught crabs in both species, although the effect was significantly more marked in Cp than Cm. Summer-caught Cp had larger excitatory junction potentials (EJPs) than did winter-caught crabs, a seasonal effect not seen in Cm. In contrast, marked seasonal differences were found in the EJP decay time constant in Cm having significantly longer time constants in winter-caught crabs, where no seasonal difference was found in Cp. These results suggest that different seasonal effects of neuromuscular parameters between Cm and Cp may reflect different strategies of response to their different seasonal temperature environments.
本研究的目的是确定两种分别在夏季和冬季捕获的十足目螃蟹的指节步足收肌神经肌肉参数对温度依赖性的季节性差异。相对狭温性的黄道蟹（Cp）和广温性的平背蜞（Cm）的肌肉静息电位（RP）随着实验温度的升高而显著超极化。在急性温度高于20°C时，Cm的肌肉RP具有季节性依赖性，而在Cp中未观察到季节性效应。在两种螃蟹中，冬季捕获的螃蟹在强直运动神经刺激后肌肉兴奋性接头电位（EJP）的潜伏期显著更长，尽管Cp中的这种效应比Cm中更明显。夏季捕获的Cp比冬季捕获的螃蟹具有更大的兴奋性接头电位（EJP），这种季节性效应在Cm中未观察到。相反，在Cm中发现EJP衰减时间常数存在明显的季节性差异，冬季捕获的螃蟹的时间常数明显更长，而在Cp中未发现季节性差异。这些结果表明，Cm和Cp之间神经肌肉参数的不同季节性效应可能反映了它们对不同季节性温度环境的不同反应策略。
