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首页> 外文期刊>The Journal of Experimental Biology >MATURATIONAL CHANGES IN TROPONIN T EXPRESSION CA2+-SENSITIVITY AND TWITCH CONTRACTION KINETICS IN DRAGONFLY FLIGHT MUSCLE
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MATURATIONAL CHANGES IN TROPONIN T EXPRESSION CA2+-SENSITIVITY AND TWITCH CONTRACTION KINETICS IN DRAGONFLY FLIGHT MUSCLE

机译：蜻蜓飞行中肌钙蛋白T表达CA2 +敏感性和抽搐收缩动力学的变化

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摘要

Maximum lift production and the thermal sensitivity of lift production increase dramatically during adult maturation of Libellula pulchella dragonflies. Here, we report that the mechanistic basis for this transition appears to involve a developmental change in protein expression, which alters the Ca2+-sensitivity of muscle activation and twitch contraction kinetics, The alternatively spliced Ca2+ regulatory protein troponin T (TnT) undergoes an isoform shift during adult maturation, Skinned (demembranated) fibers of mature flight muscle are up to 13 times more sensitive to activation by Ca2+ than skinned fibers from teneral (newly emerged adult) flight muscle, and their Ca2+-sensitivity is more strongly affected by temperature, Intact muscle from mature individuals has a shorter time to peak tension and longer time to half-relaxation during twitch contractions, which is consistent with a greater Ca2+-sensitivity of mature muscle, Because it becomes activated more quickly and relaxes more slowly, mature flight muscle is able to generate, with each twitch, more force per unit area than teneral muscle; this difference in force becomes greater at high temperatures, There do not appear to be any age-related differences in actomyosin crossbridge properties, since teneral and mature flight muscles do not differ in shortening velocity, tetanic tension or instantaneous power output during isotonic contraction, Thus, variation in TnT expression appears to affect the temperature-dependent Ca2+-sensitivity of muscle activation, which in turn affects the kinetics and force production of the twitch contractions used by dragonflies during flight, This cascade of effects suggests that maturational changes in the expression of TnT isoforms may be a key determinant of overall muscle and organismal performance. [References: 40]
机译：成年Libellula pulchella蜻蜓的成熟过程中，最大的举升产量和举升产物的热敏性显着提高。在这里，我们报告此过渡的机制基础似乎涉及蛋白质表达的发育变化，从而改变了肌肉激活和抽搐收缩动力学的Ca2 +敏感性，或者剪接的Ca2 +调节蛋白肌钙蛋白T（TnT）经历了同种型转变在成人成熟过程中，成熟的飞行肌的皮肤（去膜）纤维对Ca 2+激活的敏感性比腱（新近出现的成人）飞行肌的皮肤纤维的敏感性高13倍，并且它们的Ca 2+敏感性受温度的影响更强，完整来自成熟个体的肌肉在抽搐收缩过程中达到峰值张力的时间更短，而达到半松弛的时间更长，这与成熟肌肉对Ca2 +的敏感性更高有关，因为它的活化速度更快，放松得更慢，因此成熟的飞行肌与抽筋相比，每次抽搐能够在单位面积上产生更大的力;这种力的差异在高温下会变得更大。肌动蛋白横桥特性似乎没有任何与年龄相关的差异，因为肌腱和成熟的飞行肌在等渗收缩期间的缩短速度，强直张力或瞬时功率输出没有差异，因此，TnT表达的变化似乎会影响肌肉激活的温度依赖性Ca2 +敏感性，进而影响蜻蜓在飞行过程中使用的抽搐收缩的动力学和力产生。这种级联效应表明， TnT亚型可能是决定整体肌肉和机体性能的关键因素。 [参考：40]

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