Department of Invertebrate Zoology, Faculty of Biology, Saint Petersburg State University, Universitetskaja nab. 7/9, Saint Petersburg, Russian Federation, 199034.
Department of Biology, Randolph-Macon College, 304 Caroline Street, Ashland, VA, 23005, USA.
Sci Rep. 2021 Jan 8;11(1):4. doi: 10.1038/s41598-020-78616-4.
Bacteriophage communities associated with humans and vertebrate animals have been extensively studied, but the data on phages living in invertebrates remain scarce. In fact, they have never been reported for most animal phyla. Our ultrastructural study showed for the first time a variety of virus-like particles (VLPs) and supposed virus-related structures inside symbiotic bacteria in two marine species from the phylum Bryozoa, the cheilostomes Bugula neritina and Paralicornia sinuosa. We also documented the effect of VLPs on bacterial hosts: we explain different bacterial 'ultrastructural types' detected in bryozoan tissues as stages in the gradual destruction of prokaryotic cells caused by viral multiplication during the lytic cycle. We speculate that viruses destroying bacteria regulate symbiont numbers in the bryozoan hosts, a phenomenon known in some insects. We develop two hypotheses explaining exo- and endogenous circulation of the viruses during the life-cycle of B. neritina. Finally, we compare unusual 'sea-urchin'-like structures found in the collapsed bacteria in P. sinuosa with so-called metamorphosis associated contractile structures (MACs) formed in the cells of the marine bacterium Pseudoalteromonas luteoviolacea which are known to trigger larval metamorphosis in a polychaete worm.
与人类和脊椎动物相关的噬菌体群落已经得到了广泛的研究，但关于生活在无脊椎动物中的噬菌体的数据仍然很少。事实上，对于大多数动物门来说，它们从未被报道过。我们的超微结构研究首次表明，在苔藓动物门的两种海洋物种——贻贝和帕拉利科尼亚·西努索萨中，共生细菌内存在多种病毒样颗粒（VLPs）和假定的病毒相关结构。我们还记录了 VLPs 对细菌宿主的影响：我们将在苔藓动物组织中检测到的不同的细菌“超微结构类型”解释为在裂解周期中病毒复制导致原核细胞逐渐破坏的阶段。我们推测，破坏细菌的病毒调节了苔藓动物宿主中共生体的数量，这种现象在一些昆虫中是已知的。我们提出了两个假设，解释了在贻贝的生命周期中病毒的外源性和内源性循环。最后，我们将在帕拉利科尼亚·西努索萨中塌陷细菌中发现的异常“海胆”状结构与所谓的与变形相关的收缩结构（MACs）进行了比较，这些结构在海洋细菌 Pseudoalteromonas luteoviolacea 中形成，已知这些结构会触发多毛类环节动物的幼虫变形。
