Shimizu Daisuke, Kasagi Satoshi, Takeuchi Ryota, Maeda Tomoki, Furufuji Sumihisa, Mizusawa Kanta, Andoh Tadashi, Takahashi Akiyoshi
Miyako Laboratory, Tohoku National Fisheries Research Institute, Japan Fisheries Research and Education Agency, Miyako, Iwate 027-0097, Japan.
School of Marine Biosciences, Kitasato University, Sagamihara, Kanagawa 252-0373, Japan.
Gen Comp Endocrinol. 2019 Jan 15;271:82-90. doi: 10.1016/j.ygcen.2018.11.005. Epub 2018 Nov 9.
We have previously shown that the somatic growth of barfin flounder, Verasper moseri, was promoted by green light. The present study was undertaken to elucidate whether growth-promoting effect of green light can be observed in other flatfishes and to understand the roles of endocrine systems in green light-induced growth. Herein, we demonstrated facilitation of growth by green light in the spotted halibut, Verasper variegatus, and Japanese flounder, Paralichthys olivaceus. Blue and blue-green light showed potencies that were similar to that of green light, while the potencies of red and white light were equivalent to that of ambient light (control). We also examined the effects of green light on growth and endocrine systems of V. variegatus at various water temperatures. Growth of the fish was facilitated by green light at four different water temperatures examined; the fish were reared for 31 days at 12 and 21 °C, and 30 days at 15 and 18 °C. Increase in condition factor was observed at 15 and 18 °C. Among the genes encoding hypothalamic hormones, expression levels of melanin-concentrating hormone 1 (mch1) were enhanced by green light at the four water temperatures. Expression levels of other genes including mch2 increased at certain water temperatures. No difference was observed in the expression levels of pituitary hormone genes, including those of growth hormone and members of proopiomelanocortin family, and in plasma levels of members of the insulin family. The results suggest that green light may generally stimulate growth of flatfishes. Moreover, it is conceivable that MCH, production of which is stimulated by green light, is a key hormone; it augments food intake, which is intimately coupled with somatic growth.
我们之前已经表明，绿光可促进条石鲷（Verasper moseri）的体细胞生长。本研究旨在阐明绿光促进生长的作用是否也能在其他比目鱼中观察到，并了解内分泌系统在绿光诱导生长中的作用。在此，我们证明了绿光可促进斑头鲆（Verasper variegatus）和牙鲆（Paralichthys olivaceus）的生长。蓝光和蓝绿光的促进生长效力与绿光相似，而红光和白光的效力与环境光（对照）相当。我们还研究了不同水温下绿光对斑头鲆生长和内分泌系统的影响。在所检测的四个不同水温下，绿光均促进了鱼的生长；鱼在12℃和21℃下饲养31天，在15℃和18℃下饲养30天。在15℃和18℃时观察到肥满度增加。在编码下丘脑激素的基因中，在四个水温下，绿光均增强了促黑素细胞激素1（mch1）的表达水平。包括mch2在内的其他基因的表达水平在某些水温下有所增加。垂体激素基因（包括生长激素和阿黑皮素原家族成员）的表达水平以及胰岛素家族成员的血浆水平均未观察到差异。结果表明，绿光可能普遍刺激比目鱼的生长。此外，可以想象，受绿光刺激而产生的促黑素细胞激素是一种关键激素；它增加食物摄入量，而食物摄入量与体细胞生长密切相关。
