Ecological dynamics of the bivalve‐killing dinoflagellate <i>Heterocapsa circularisquama</i> and its infectious viruses in different locations of western Japan

Tomaru, Yuji; Hata, Naotsugu; Masuda, Takeshi; Tsuji, Masaharu; Igata, Kuniyoshi; Masuda, Yuji; Yamatogi, Toshifumi; Sakaguchi, Masao; Nagasaki, Keisuke

doi:10.1111/j.1462-2920.2007.01252.x

Cited by 64 publications

(66 citation statements)

References 19 publications

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“…We detected H. circularisquama cells at considerably lower concentrations from the water samples on the sampling day (see Materials and Methods). In our previous surveys, H. circularisquama blooms were accompanied by the occurrence of viruses lytic to H. circularisquama , Tomaru et al 2007). From the above results, the viruses isolated in this study were considered to be HcV and HcRNAV; and were propagated during the process of a H. circularisquama bloom that occurred just before our sampling in October 2006.…”

Section: Discussionmentioning

confidence: 89%

“…The other, a small single-stranded RNA (ssRNA) virus, H. circularisquama RNA virus (HcRNAV), was later isolated from most H. circularisquama bloom waters in western Japan . Simultaneous occurrence of H. circularisquama blooms and viruses (including unidentified species) in western Japan have been observed almost every year since 2001; and most of the viruses were recognized as HcRNAV using molecular biological methods (Tomaru et al 2007). Therefore, HcRNAV infection is considered to be one of the most significant factors affecting the population dynamics of H. circularisquama , Tomaru et al 2007).…”

Section: Introductionmentioning

confidence: 99%

“…Simultaneous occurrence of H. circularisquama blooms and viruses (including unidentified species) in western Japan have been observed almost every year since 2001; and most of the viruses were recognized as HcRNAV using molecular biological methods (Tomaru et al 2007). Therefore, HcRNAV infection is considered to be one of the most significant factors affecting the population dynamics of H. circularisquama , Tomaru et al 2007). On the other hand, the ecological relationship between H. circularisquama blooms and HcV is poorly understood.…”

Section: Introductionmentioning

confidence: 99%

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Co-occurrence of DNA- and RNA-viruses infecting the bloom-forming dinoflagellate, Heterocapsa circularisquama, on the Japan coast

Tomaru

Mizumoto

Takao

et al. 2009

Plankton Benthos Res

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Abstract:In western Japan, Heterocapsa circularisquama blooms occur almost every year. Two distinct viruses infectious to H. circularisquama, a large double-stranded DNA (dsDNA) virus, 'HcV', and a small single-stranded RNA (ssRNA) virus, 'HcRNAV', were found and characterized. Here we report the co-occurrence of the two viruses in Hiroshima Bay, Japan, during 2006. Viruses isolated using H. circularisquama strains HU9433-P and MZ2 (the hosts) were large dsDNA viruses (ca. 0.2 mm in diameter) that accumulated in the host cytoplasm. Pulsed-field gel electrophoresis analysis showed their genome sizes were ca. 388 kbp, comparable to the previously reported HcV strain. Small ssRNA viruses were also isolated (using the host strain HCLG-1) at ca. 30 nm in diameter and formed crystalline arrays and/or were randomly accumulated in the host cytoplasm, and their partial genome sequences were highly similar to a previously reported HcRNAV strain. This is the first report of the co-occurrence of HcV and HcRNAV in natural water and their successful isolation. The data suggest the two distinct viruses may cooperatively affect the dynamics of H. circularisquama blooms.

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Section: Discussionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Co-occurrence of DNA- and RNA-viruses infecting the bloom-forming dinoflagellate, Heterocapsa circularisquama, on the Japan coast

Tomaru

Mizumoto

Takao

et al. 2009

Plankton Benthos Res

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“…Their high abundance and obligately parasitic lifestyle allow viruses to exert top-down control of cellular organism populations, which is illustrated most dramatically through the implication that viruses are involved in the termination of some algal blooms (e.g., Bratbak et al, 1993;Tarutani et al, 2000;Wilson et al, 2002;Brussaard et al, 2005: Gobler et al, 2007Tomaru et al, 2007). More subtly, viruses contribute to the mortality of bacteria, phytoplankton and higher trophic levels of the aquatic food web (Proctor and Fuhrman, 1990;Suttle, 1994;Baudoux et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Seasonal determinations of algal virus decay rates reveal overwintering in a temperate freshwater pond

Long

Short

2016

The ISME Journal

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To address questions about algal virus persistence (i.e., continued existence) in the environment, rates of decay of infectivity for two viruses that infect Chlorella-like algae, ATCV-1 and CVM-1, and a virus that infects the prymnesiophyte Chrysochromulina parva, CpV-BQ1, were estimated from in situ incubations in a temperate, seasonally frozen pond. A series of experiments were conducted to estimate rates of decay of infectivity in all four seasons with incubations lasting 21 days in spring, summer and autumn, and 126 days in winter. Decay rates observed across this study were relatively low compared with previous estimates obtained for other algal viruses, and ranged from 0.012 to 11% h − 1 . Overall, the virus CpV-BQ1 decayed most rapidly whereas ATCV-1 decayed most slowly, but for all viruses the highest decay rates were observed during the summer and the lowest were observed during the winter. Furthermore, the winter incubations revealed the ability of each virus to overwinter under ice as ATCV-1, CVM-1 and CpV-BQ1 retained up to 48%, 19% and 9% of their infectivity after 126 days, respectively. The observed resilience of algal viruses in a seasonally frozen freshwater pond provides a mechanism that can support the maintenance of viral seed banks in nature. However, the high rates of decay observed in the summer demonstrate that virus survival and therefore environmental persistence can be subject to seasonal bottlenecks.

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“…Previous reports have documented 10-fold differences in the total abundance of aquatic virus communities between summer and winter months (Wommack and Colwell, 2000;Li and Dickie, 2001), and rapid changes in virus abundances in nutrient amended seawater enclosures Larsen et al, 2001). The abundances of viruses that infect single strains of phytoplankton, such as Heterocapsa circularisquama (Tomaru et al, 2007), Micromonas pusilla (Cottrell and Suttle, 1995;Zingone et al, 1999) and Synechococcus spp. (Suttle and Chan, 1994), vary seasonally and range from undetectable to 410 5 infectious units ml À1 .…”

Section: Introductionmentioning

confidence: 99%

Quantification of virus genes provides evidence for seed-bank populations of phycodnaviruses in Lake Ontario, Canada

2010

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Using quantitative PCR, the abundances of six phytoplankton viruses DNA polymerase (polB) gene fragments were estimated in water samples collected from Lake Ontario, Canada over 26 months. Four of the polB fragments were most related to marine prasinoviruses, while the other two were most closely related to cultivated chloroviruses. Two Prasinovirus-related genes reached peak abundances of 41000 copies ml À1 and were considered 'high abundance', whereas the other two Prasinovirus-related genes peaked at abundances o1000 copies ml À1 and were considered 'low abundance'. Of the genes related to chloroviruses, one peaked at ca 1600 copies ml À1 , whereas the other reached only ca 300 copies ml À1 . Despite these differences in peak abundance, the abundances of all genes monitored were lowest during the late fall, winter and early spring; during these months the high abundance genes persisted at 100-1000 copies ml À1 while the low abundance Prasinovirus-and Chlorovirus-related genes persisted at fewer than ca 100 copies ml À1 . Clone libraries of psbA genes from Lake Ontario revealed numerous Chlorella-like algae and two prasinophytes demonstrating the presence of candidate hosts for all types of viruses monitored. Our results corroborate recent metagenomic analyses that suggest that aquatic virus communities are composed of only a few abundant populations and many low abundance populations. Thus, we speculate that an ecologically important characteristic of phycodnavirus communities is seed-bank populations with members that can become numerically dominant when their host abundances reach appropriate levels.

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Ecological dynamics of the bivalve‐killing dinoflagellate Heterocapsa circularisquama and its infectious viruses in different locations of western Japan

Cited by 64 publications

References 19 publications

Co-occurrence of DNA- and RNA-viruses infecting the bloom-forming dinoflagellate, Heterocapsa circularisquama, on the Japan coast

Co-occurrence of DNA- and RNA-viruses infecting the bloom-forming dinoflagellate, Heterocapsa circularisquama, on the Japan coast

Seasonal determinations of algal virus decay rates reveal overwintering in a temperate freshwater pond

Quantification of virus genes provides evidence for seed-bank populations of phycodnaviruses in Lake Ontario, Canada

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