Wolinska J, King K C, Vigneux F, Lively C M
Indiana University, Department of Biology, 1001 East 3rd Street, Bloomington, Indiana 47405, USA.
Parasitology. 2008 Dec;135(14):1667-78. doi: 10.1017/S0031182008005052. Epub 2008 Nov 10.
We describe the infectivity, virulence, cultivating conditions, and phylogenetic positions of naturally occurring oomycete parasites of Daphnia, invertebrates which play a major role in aquatic food webs. Daphnia pulex individuals were found dead and covered by oomycete mycelia when exposed to pond sediments. We were able to extract 4 oomycete isolates from dead Daphnia and successfully cultivate them. Using the ITS and LSU rDNA sequences, we further showed these isolates to be distinct species. The isolates were experimentally demonstrated to be parasitic and not saprobic. After exposure to the parasites, Daphnia mortality was much higher than that reported for Daphnia infected with other known parasite species. Therefore, it is likely that oomycete parasites are important selective pressures in natural Daphnia populations. Moreover, their close phylogenetic relationship to parasites of fish and algae suggests that the stability of aquatic food webs (i.e. fish-Daphnia-algae) might be influenced by the shared parasite communities.
我们描述了水蚤（在水生食物网中起主要作用的无脊椎动物）自然存在的卵菌寄生虫的传染性、毒力、培养条件和系统发育位置。当水蚤暴露于池塘沉积物时，发现其个体死亡并被卵菌菌丝体覆盖。我们能够从死亡的水蚤中提取4种卵菌分离株并成功培养它们。利用ITS和LSU rDNA序列，我们进一步证明这些分离株是不同的物种。实验证明这些分离株是寄生性的而非腐生性的。暴露于这些寄生虫后，水蚤的死亡率远高于感染其他已知寄生虫物种的水蚤。因此，卵菌寄生虫很可能是自然水蚤种群中的重要选择压力。此外，它们与鱼类和藻类寄生虫的密切系统发育关系表明，水生食物网（即鱼-水蚤-藻类）的稳定性可能会受到共享寄生虫群落的影响。
