Département de Biochimie, de Microbiologie et de Bio-Informatique, Université Laval, Québec City, QC G1V 0A6, Canada.
Centre de Recherche du Centre Hospitalier de l'Université Laval-Québec, Québec City, QC G1V 4G2, Canada.
Viruses. 2018 Nov 27;10(12):672. doi: 10.3390/v10120672.
The St. Lawrence hydrographic system includes freshwater, brackish, and marine habitats, and is the largest waterway in North America by volume. The food-webs in these habitats are ultimately dependent on phytoplankton. Viral lysis is believed to be responsible for a major part of phytoplankton mortality. To better understand their role, we characterized the diversity and distribution of two viral taxa infecting phytoplankton: the picornaviruses and phycodnaviruses. Our study focused on the estuary transition zone, which is an important nursery for invertebrates and fishes. Both viral taxa were investigated by PCR amplification of conserved molecular markers and next-generation sequencing at six sites, ranging from freshwater to marine. Our results revealed few shared viral phylotypes between saltwater and freshwater sites. Salinity appeared to be the primary determinant of viral community composition. Moreover, our analysis indicated that the viruses identified in this region of the St. Lawrence diverge from classified viruses and homologous published environmental virotypes. These results suggest that DNA and RNA viruses infecting phytoplankton are likely active in the estuary transition zone, and that this region harbors its own unique viral assemblages.
圣劳伦斯水系包括淡水、半咸水和海洋生境，是北美的最大水系。这些生境中的食物网最终依赖于浮游植物。病毒裂解被认为是浮游植物死亡的主要原因之一。为了更好地了解它们的作用，我们对感染浮游植物的两种病毒群进行了多样性和分布特征的研究：微小核糖核酸病毒和噬藻体病毒。我们的研究重点是河口过渡区，这是无脊椎动物和鱼类的重要育雏区。通过对六个地点（从淡水到海洋）的保守分子标记物的 PCR 扩增和下一代测序，研究了这两种病毒群。我们的结果表明，咸水和淡水地点之间共享的病毒同系物很少。盐度似乎是病毒群落组成的主要决定因素。此外，我们的分析表明，在圣劳伦斯河地区鉴定出的病毒与分类病毒和同源已发表的环境病毒类型不同。这些结果表明，感染浮游植物的 DNA 和 RNA 病毒可能在河口过渡区活跃，并且该地区拥有自己独特的病毒组合。
