Repeated phenotypic selection for cuticular blackness of armyworm larvae decreased stress resistance.
Repeated phenotypic selection for cuticular blackness of armyworm larvae decreased stress resistance.
复制标题
粘虫幼虫表皮黑色度的反复表型选择降低了抗逆性。
DOI：
10.1016/j.jinsphys.2019.05.007
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Yoichi Hayakawa
中科院分区：
文献类型：
--
作者：
Takashi Matsumura;Hikaru Taya;Hitoshi Matsumoto;Yoichi Hayakawa
粘虫Mythimna separatalarcium显示取决于人口密度的角质层变暗的变化，并大致分为两种表型，淡褐色的独居型和黑色的群居型。虽然这两种幼虫类型的颜色差异是明显的，但仍然不清楚是否有任何生理特征的变化伴随着角质层变暗。为了回答这个问题，我们在我们的实验室菌落中重复了100代以上的黑色表型的遗传选择，并产生了黑色（BL）菌株。非选择性对照（CTL）和BL株之间的比较显示，与CTL株相比，BL株的繁殖力和成虫寿命增加。与此相反，BL系幼虫被发现是显着更敏感的热应激比那些在CTL株。在非应激和热应激条件下，BL品系的血淋巴活性氧（ROS）水平均高于CTL品系。在非应激条件下，两品系血淋巴的抗氧化活性差异不显著，但热应激后，CTL品系血淋巴的抗氧化活性明显高于BL品系。热处理后，CTL系幼虫脂肪体内过氧化氢酶和超氧化物歧化酶（SOD）等抗氧化酶的活性和基因表达水平显着高于BL系幼虫。两个品系杂交后代的热应激耐受性与母本相当：CTL雌性与BL雄性杂交后代的热应激耐受性高于相反方向杂交的后代。发现前一个后代的抗氧化酶基因的表达水平与CTL株相似。这些结果表明，繁殖活动和抗逆性之间的权衡：BL株获得了高繁殖力，但通过重复的遗传选择已经失去了胁迫耐受性。此外，目前的遗传分析表明，耐逆表型来自母本。
ArmywormMythimna separatalarvae show changes in cuticle darkening depending on population densities and are roughly categorized into two phenotypes, a pale brown solitary type and black-colored gregarious type. Although the color difference in both larval types is apparent, it remains ambiguous whether any change in physiological traits accompanies the cuticle darkening. To answer this query, we repeated genetic selection of the blackness phenotype over one hundred generations in our laboratory colony and produced a black-colored (BL) strain. Comparison between non-selected control (CTL) and BL strains revealed an increased fecundity and adult life span in the BL strain compared with the CTL strain. In contrast, BL strain larvae were found to be significantly more sensitive to heat stress than those in the CTL strain. Hemolymph reactive oxygen species (ROS) levels were higher in the BL strain than in the CTL strain under both non-stress and heat stress conditions. Antioxidant activities of the hemolymph were not significantly different between the two strains under non-stress condition, but the activities increased to higher levels in the CTL strain than those in the BL strain after heat stress. Activities and gene expression levels of antioxidant enzymes such as catalase and superoxide dismutase (SOD) in the fat body were significantly higher in CTL strain larvae than in BL strain larvae after heat treatment. Thermal stress tolerance of the offspring of crossings between the two strains showed a tolerance level almost equivalent to the maternal one: the cross between CTL females and BL males produced offspring with the higher tolerance compared with the oppositely crossed offspring. Expression levels of the antioxidant enzyme genes of the former offspring were found to be similar to those of CTL strain. These results indicate a trade-off between reproductive activity and stress resistance: the BL strain had acquired high reproductivity but had lost stress tolerance through repeated genetic selection. Furthermore, the present genetic analyses demonstrated that the phenotype of stress tolerance is derived from the maternal parent.