Mao Beatrice, Moss Cynthia F, Wilkinson Gerald S
Department of Biology, College of Computer, Mathematical, and Natural Sciences, University of Maryland, College Park, Maryland, United States of America.
Department of Psychological and Brain Sciences, Zanvyl Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, Maryland, United States of America.
PLoS One. 2017 Oct 26;12(10):e0186667. doi: 10.1371/journal.pone.0186667. eCollection 2017.
For echolocating bats, hearing is essential for survival. Specializations for detecting and processing high frequency sounds are apparent throughout their auditory systems. Recent studies on echolocating mammals have reported evidence of parallel evolution in some hearing-related genes in which distantly related groups of echolocating animals (bats and toothed whales), cluster together in gene trees due to apparent amino acid convergence. However, molecular adaptations can occur not only in coding sequences, but also in the regulation of gene expression. The aim of this study was to examine the expression of hearing-related genes in the inner ear of developing big brown bats, Eptesicus fuscus, during the period in which echolocation vocalizations increase dramatically in frequency. We found that seven genes were significantly upregulated in juveniles relative to adults, and that the expression of four genes through development correlated with estimated age. Compared to available data for mice, it appears that expression of some hearing genes is extended in juvenile bats. These results are consistent with a prolonged growth period required to develop larger cochlea relative to body size, a later maturation of high frequency hearing, and a greater dependence on high frequency hearing in echolocating bats.
对于使用回声定位的蝙蝠来说，听觉是生存所必需的。在它们的整个听觉系统中，用于检测和处理高频声音的特化现象很明显。最近对使用回声定位的哺乳动物的研究报告了一些与听力相关基因平行进化的证据，在这些基因中，关系较远的回声定位动物群体（蝙蝠和齿鲸）由于明显的氨基酸趋同而在基因树中聚集在一起。然而，分子适应不仅可以发生在编码序列中，也可以发生在基因表达的调控中。本研究的目的是检查发育中的大棕蝠（Eptesicus fuscus）内耳中与听力相关基因在回声定位发声频率急剧增加期间的表达情况。我们发现，与成年蝙蝠相比，幼年蝙蝠中有七个基因显著上调，并且四个基因在发育过程中的表达与估计年龄相关。与小鼠的现有数据相比，幼年蝙蝠中一些听力基因的表达似乎有所延长。这些结果与蝙蝠相对于体型需要更长的生长期来发育更大的耳蜗、高频听力成熟较晚以及对高频听力有更大依赖性是一致的。
