Kumagai Akira, Ito Hiroshi, Sasaki Ryo
Miyagi Prefecture Fisheries Technology Institute Freshwater Fisheries, Experimental Station, Taiwa, Miyagi 981-3625, Japan.
Dis Aquat Organ. 2013 Nov 6;106(3):267-71. doi: 10.3354/dao02653.
The occurrence of soft tunic syndrome in wild populations of the ascidian Halocynthia roretzi was monitored by diving at 5 to 6 sites in Miyagi Prefecture in Japan in summer 2010 and 2011. These sites were located at varying distances from farming sites at which the disease had previously been detected. All dead ascidians were collected, and their tunics were examined for Azumiobodo hoyamushi, the causative agent of soft tunic syndrome, using 18S rRNA PCR. In both years, <1% of wild ascidians we observed (18 out of 2100 in 2010, and 30 out of 3100 in 2011) were dead. The flagellates were only detected in 8 out of 18 dead ascidians from 3 sites in 2010, and 4 out of 30 from 2 sites in 2011. Healthy ascidians were successfully experimentally infected with the disease by immersing tunic samples from diseased wild ascidians into the rearing water. When apparently healthy ascidians collected from the wild population were reared for 40 d using pathogen-free water, the tunics of some ascidians became softened. The flagellates were detected in these individuals, which were diagnosed with soft tunic syndrome. Our results suggest that soft tunic syndrome affects the wild population of ascidians in Japan.
2010年和2011年夏季，通过潜水对日本宫城县5至6个地点的野生群体柄海鞘软被囊综合征的发生情况进行了监测。这些地点与之前检测到该病的养殖地点距离各不相同。收集了所有死亡的海鞘，并使用18S rRNA PCR对其被囊进行检查，以检测软被囊综合征的病原体——保科波豆虫。在这两年中，我们观察到的野生海鞘中死亡的比例均小于1%（2010年2100个中有18个，2011年3100个中有30个）。仅在2010年来自3个地点的18个死亡海鞘中的8个，以及2011年来自2个地点的30个中的4个中检测到了鞭毛虫。通过将患病野生海鞘的被囊样本浸入养殖水中，成功地使健康海鞘在实验中感染了该病。当使用无病原体的水将从野生群体中收集的看似健康的海鞘饲养40天时，一些海鞘的被囊变软。在这些被诊断患有软被囊综合征的个体中检测到了鞭毛虫。我们的结果表明，软被囊综合征影响了日本海鞘的野生群体。
