Feehan Colette J, Johnson-Mackinnon Jessica, Scheibling Robert E, Lauzon-Guay Jean-Sébastien, Simpson Alastair G B
Biology Department, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada.
Dis Aquat Organ. 2013 Apr 11;103(3):209-27. doi: 10.3354/dao02577.
Green sea urchins Strongylocentrotus droebachiensis along the coast of Nova Scotia, Canada, suffer mass mortalities from infection by the pathogenic amoeba Paramoeba invadens Jones, 1985. It has been speculated that P. invadens could be a form of Neoparamoeba pemaquidensis, a species associated with disease in S. droebachiensis and lobsters in the northeast USA. During a disease outbreak in fall 2011, we isolated amoebae from moribund urchins collected from 4 locations along ~200 km of coastline. In laboratory infection trials, we found that timing and rate of morbidity corresponded to that of similar experiments conducted in the early 1980s, when P. invadens was first identified. All isolates had a similar size and morphology to the original description, including an absence of microscales. Sequences of nuclear SSU rDNA show that disease was caused by one 'species' of amoeba across the range sampled. Phylogenetic analyses prove that P. invadens is not conspecific with N. pemaquidensis, but is a distinct species most closely related to N. branchiphila, a suspected pathogen of sea urchins Diadema aff. antillarum in the Canary Islands, Spain. Morphology and closest phylogenetic affinities suggest that P. invadens would be assignable to the genus Neoparamoeba; however, nuclear SSU rDNA trees show that Neoparamoeba and Paramoeba are phylogenetically inseparable. Therefore, we treat Neoparamoeba as a junior synonym of Paramoeba, with P. invadens retaining that name, and N. pemaquidensis and N. aestuarina reverting to their original names (P. pemaquidensis and P. aestuarina), and with new combinations for N. branchiphila Dykova et al., 2005, and N. perurans Young et al., 2007, namely P. branchiphila comb. nov. and P. perurans comb. nov.
在加拿大新斯科舍省沿海，绿海胆（Strongylocentrotus droebachiensis）会因感染致病性变形虫——侵袭副变形虫（Paramoeba invadens Jones，1985）而大量死亡。据推测，侵袭副变形虫可能是佩马奎德新副变形虫（Neoparamoeba pemaquidensis）的一种形态，该物种与美国东北部绿海胆和龙虾的疾病有关。在2011年秋季的一次疾病暴发期间，我们从沿着约200千米海岸线的4个地点采集的濒死海胆中分离出了变形虫。在实验室感染试验中，我们发现发病时间和发病率与20世纪80年代初首次鉴定出侵袭副变形虫时进行的类似实验相符。所有分离株的大小和形态都与最初描述的相似，包括没有微鳞片。核糖体小亚基（SSU）rDNA的序列表明，在采样范围内，疾病是由一种变形虫“物种”引起的。系统发育分析证明，侵袭副变形虫与佩马奎德新副变形虫并非同种，但它是一个独特的物种，与分支新副变形虫（Neoparamoeba branchiphila）关系最为密切，分支新副变形虫是西班牙加那利群岛海胆（Diadema aff. antillarum）的一种疑似病原体。形态学和最接近的系统发育亲缘关系表明，侵袭副变形虫可归入新副变形虫属；然而，核糖体小亚基rDNA树状图显示，新副变形虫属和副变形虫属在系统发育上无法区分。因此，我们将新副变形虫属视为副变形虫属的次异名，侵袭副变形虫保留该名称，佩马奎德新副变形虫和河口新副变形虫（N. aestuarina）恢复其原名（佩马奎德副变形虫（P. pemaquidensis）和河口副变形虫（P. aestuarina）），并对2005年迪科娃等人描述的分支新副变形虫和2007年扬等人描述的秘鲁新副变形虫（N. perurans）进行新组合，即分支副变形虫（Paramoeba branchiphila comb. nov.）和秘鲁副变形虫（Paramoeba perurans comb. nov.）。
