Hiroyoshi Satoshi, Yoshimura Jin, Iwabuchi Kikuo, Reddy Gadi V P, Mitsuhashi Jun
Laboratory of Applied Entomology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan.
Graduate School of Science and Technology and Department of Mathematical and Systems Engineering, Shizuoka University, Hamamatsu 432-8561, Japan; Marine Biosystems Research Center, Chiba University, Kamogawa, Chiba 299-5502, Japan; Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, NY 13210, USA.
J Insect Physiol. 2017 Jul;100:1-8. doi: 10.1016/j.jinsphys.2017.04.008. Epub 2017 Apr 27.
Sperm polymorphism is widely known in invertebrates. In insects, Lepidoptera has two types of sperm: nucleated eupyrene (fertile) sperm and anucleated apyrene (unfertile) sperm. These sperm types are produced during post-embryogenesis, and eupyrene spermatogenesis precedes apyrene spermatogenesis. During overwintering, spermatogenesis stops and a portion of undifferentiated-stage spermatocytes degenerate. After overwintering, spermatogenesis restarts with unaffected spermatogonia. However, how new spermatozoa arise in the adult testes after overwintering is not known in Lepidoptera. In this study, we investigated the spermatogenesis events in the nymphalid butterfly Polygonia c-aureum after overwintering under various environmental conditions. Our results indicate that both eupyrene and apyrene spermatogenesis restart at any stopping stage and sperm of these types are regenerated in no particular order after adult insect overwintering. This suggests that the spermatogenesis occurring after overwintering proceeds without embryogenetic restrictions related to the developmental sequence.
精子多态性在无脊椎动物中广为人知。在昆虫中，鳞翅目有两种类型的精子：有核的真核精子（可育）和无核的无核精子（不育）。这些精子类型在胚胎后期发育过程中产生，真核精子发生先于无核精子发生。在越冬期间，精子发生停止，一部分未分化阶段的精母细胞退化。越冬后，精子发生随着未受影响的精原细胞重新开始。然而，在鳞翅目中，越冬后成年睾丸中如何产生新的精子尚不清楚。在本研究中，我们调查了蛱蝶科蝴蝶黄钩蛱蝶在各种环境条件下越冬后的精子发生事件。我们的结果表明，真核精子和无核精子的发生在任何停止阶段都会重新开始，并且在成年昆虫越冬后，这些类型的精子会以无特定顺序再生。这表明越冬后发生的精子发生过程不受与发育序列相关的胚胎发生限制。
