Yokoyama Hiroshi, Ogawa Kazuo
Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo, Tokyo 113-8657, Japan.
Meguro Parasitological Museum, Shimomeguro 4-1-1, Meguro, Tokyo 153-0064, Japan.
Parasitol Int. 2015 Aug;64(4):43-7. doi: 10.1016/j.parint.2015.01.008. Epub 2015 Jan 29.
Myxobolus toyamai has long been known as a gill parasite of the common carp Cyprinus carpio in Europe, Asia and North America. Recently, a controversy was raised regarding whether this organism was synonymous with Thelohanellus toyamai because of ambiguity regarding the validity of the second stunted polar capsule. In the present study, detailed morphological examinations were conducted to reconfirm the presence of the small polar capsule of M. toyamai. The addition of potassium hydroxide or the application of drying treatment to fresh spores resulted in the extrusion of long and short polar filament from the spores. Transmission electron microscopy of M. toyamai plasmodia revealed that the polar filament coiled inside the small capsule. Molecular analysis of the 18S rDNA identified that the present myxosporean isolate was the same organism as the American and Japanese isolates that have previously been registered as T. toyamai and M. toyamai, respectively (99.5-99.8% similarities). These results demonstrate that the second small polar capsule was indeed present in the myxosporean isolate, which indicates that M. toyamai is a valid scientific name.
丰田碘泡虫长期以来一直被认为是欧洲、亚洲和北美的鲤鱼（Cyprinus carpio）鳃部的寄生虫。最近，由于第二极囊发育不全的有效性存在模糊性，引发了关于这种生物是否与富山泰洛汉虫同义的争议。在本研究中，进行了详细的形态学检查，以再次确认丰田碘泡虫小极囊的存在。向新鲜孢子中添加氢氧化钾或进行干燥处理，会导致孢子挤出长短不一的极丝。丰田碘泡虫多核体的透射电子显微镜观察显示，极丝盘绕在小囊内。对18S rDNA的分子分析表明，目前的粘孢子虫分离株与之前分别登记为富山泰洛汉虫和丰田碘泡虫的美国和日本分离株是同一生物（相似度为99.5 - 99.8%）。这些结果表明，在该粘孢子虫分离株中确实存在第二小极囊，这表明丰田碘泡虫是一个有效的学名。
