Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland.
Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland.
J Invertebr Pathol. 2019 Sep;166:107218. doi: 10.1016/j.jip.2019.107218. Epub 2019 Jul 19.
The genus Aphanomyces (Oomycetes) comprises approximately 50 known species of water molds in three lineages. One of the most notorious is Aphanomyces astaci, the causative agent of crayfish plague. In this study, fresh isolates of Aphanomyces were collected from 20 live specimens of the signal crayfish Pacifastacus leniusculus (Dana, 1852) from Lake Tahoe, California, providing 35 axenic cultures of A. astaci as well as two apparently undescribed Aphanomyces spp. isolates. Based on the results of ITS-, chitinase-, mitochondrial rnnS- and rnnL-sequences and microsatellite markers combined, the Lake Tahoe A. astaci isolates were identical to isolates of A. astaci B-haplogroup commonly detected in Europe, and infection experiments confirmed their high virulence towards noble crayfish. One of the two undescribed Aphanomyces spp. isolates was highly similar to an Aphanomyces lineage detected previously in crustacean zooplankton (Daphnia) in Central Europe, while the other was distinct and most closely related (ITS sequence similarity of 93%) to either A. astaci or to Aphanomyces fennicus isolated recently from Astacus astacus in Finland. Neither of the two Aphanomyces spp. isolates caused crayfish mortality under experimental conditions. Our results indicate that the populations of North American signal crayfish can act as carriers of both pathogenic and non-pathogenic Aphanomyces at the same time. Furthermore, considering that a limited number of crayfish individuals from a single location yielded multiple distinct Aphanomyces isolates, our results suggest that substantial species diversity within this genus remains undescribed.
该属 Aphanomyces（卵菌纲）包含约 50 种已知的水霉，分为三个谱系。其中最臭名昭著的是引起小龙虾瘟疫的 Aphanomyces astaci。在这项研究中，从加利福尼亚州塔霍湖的 20 只活的信号小龙虾（Pacifastacus leniusculus（Dana，1852））中采集了新鲜的 Aphanomyces 分离株，提供了 35 个 A. astaci 的无菌培养物以及两个显然未被描述的 Aphanomyces spp. 分离株。根据 ITS-、几丁质酶-、线粒体 rnnS- 和 rnnL-序列以及微卫星标记的综合结果，塔霍湖的 A. astaci 分离株与欧洲常见的 A. astaci B 单倍型的分离株相同，感染实验证实它们对高贵小龙虾具有高致病性。两个未被描述的 Aphanomyces spp. 分离株之一与先前在中欧甲壳类浮游动物（水蚤）中检测到的 Aphanomyces 谱系高度相似，而另一个则明显不同，与最近从芬兰的 Astacus astacus 中分离出的 A. astaci 或 Aphanomyces fennicus 最为密切相关（ITS 序列相似性为 93%）。在实验条件下，这两个 Aphanomyces spp. 分离株均未引起小龙虾死亡。我们的结果表明，北美信号小龙虾的种群可以同时携带致病性和非致病性的 Aphanomyces。此外，考虑到从一个单一地点采集的有限数量的小龙虾个体产生了多个不同的 Aphanomyces 分离株，我们的结果表明该属内仍有大量未被描述的物种多样性。
