Muscedere Mario L, Traniello James F A, Gronenberg Wulfila
Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA.
Naturwissenschaften. 2011 Sep;98(9):783-93. doi: 10.1007/s00114-011-0828-6. Epub 2011 Jul 27.
Although several neurobiological and genetic correlates of aging and behavioral development have been identified in social insect workers, little is known about how other age-related physiological processes, such as muscle maturation, contribute to task performance. We examined post-eclosion growth of three major muscles of the head capsule in major and minor workers of the ant Pheidole dentata using workers of different ages with distinct task repertoires. Mandible closer muscle fibers, which provide bite force and are thus critical for the use of the mandibles for biting and load carrying, fill the posterio-lateral portions of the head capsule in mature, older workers of both subcastes. Mandible closer fibers of newly eclosed workers, in contrast, are significantly thinner in both subcastes and grow during at least the next 6 days in minor workers, suggesting this muscle has reduced functionality for a substantial period of adult life and thus constrains task performance capability. Fibers of the antennal muscles and the pharynx dilator, which control antennal movements and food intake, respectively, also increase significantly in thickness with age. However, these fibers are only slightly thinner in newly eclosed workers and attain their maximum thickness over a shorter time span in minors. The different growth rates of these functionally distinct muscles likely have consequences for how adult P. dentata workers, particularly minors, develop their full and diverse task repertoire as they age. Workers may be capable of feeding and interacting socially soon after eclosion, but require a longer period of development to effectively use their mandibles, which enable the efficient performance of tasks ranging from nursing to foraging and defense.
虽然在社会性昆虫工蚁中已经发现了衰老和行为发育的几种神经生物学和遗传相关性，但对于其他与年龄相关的生理过程，如肌肉成熟，如何影响任务表现却知之甚少。我们使用具有不同任务种类的不同年龄的工蚁，研究了齿胸蚁大工蚁和小工蚁头部外壳三块主要肌肉羽化后的生长情况。下颌闭合肌纤维提供咬合力，因此对于使用下颌进行咬和承载负荷至关重要，在两个亚等级的成熟、年长工蚁中，这些纤维填充了头部外壳的后外侧部分。相比之下，新羽化工蚁的下颌闭合肌纤维在两个亚等级中都明显更细，并且在小工蚁中至少在接下来的6天内还会生长，这表明这块肌肉在成年后的相当长一段时间内功能有所降低，从而限制了任务执行能力。分别控制触角运动和食物摄入的触角肌纤维和咽扩张肌纤维的厚度也随着年龄显著增加。然而，这些纤维在新羽化工蚁中只是略细一些，并且在小工蚁中在更短的时间内达到最大厚度。这些功能不同的肌肉不同的生长速度可能会影响成年齿胸蚁工蚁，尤其是小工蚁，随着年龄增长如何发展出完整多样的任务种类。工蚁在羽化后可能很快就能进食和进行社交互动，但需要更长的发育时间才能有效地使用它们的下颌，而下颌能使从护理到觅食和防御等各种任务高效执行。
