The Experts below are selected from a list of 52305 Experts worldwide ranked by ideXlab platform
Keizo Nagasaki - One of the best experts on this subject based on the ideXlab platform.
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Isolation and characterization of a single‐stranded RNA Virus that infects the marine planktonic diatom Chaetoceros sp. (SS08‐C03)
Phycological Research, 2012Co-Authors: Yuji Tomaru, Yoshitake Takao, Kensuke Toyoda, Kei Kimura, Kiyonari Sakurada, Natsuko Nakayama, Keizo NagasakiAbstract:Summary Diatoms are the major primary producers in the world's aquatic environment; hence, their dynamics are an important focus in current studies. Viruses, along with other physical, chemical, and biological factors, have recently been recognized as potential factors of diatom mortality. We isolated and characterized a new diatom Virus (Csp03RNAV) that causes lysis of the marine planktonic diatom Chaetoceros sp. strain SS08-C03 isolated from Hiroshima Bay, Japan. Here, we present the physiology, morphology, and genome characteristics of this Virus. Csp03RNAV was isolated from surface waters of Yatsushiro Sea, Japan. Virions were icosahedral and 32 nm in diameter, and accumulated in the cytoplasm of the host cells. The latent period was estimated to be
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Crystallization and preliminary X-ray analysis of a marine diatom-infecting Single-Stranded RNA Virus.
Acta Crystallographica Section F Structural Biology and Crystallization Communications, 2010Co-Authors: Hisashi Naitow, Yuji Tomaru, Yoko Shirai, Keizo NagasakiAbstract:Crystals of a diatom-infecting Virus (CtenRNAV) that diffracted to a resolution of 4.0 A were grown in a mixture of 2-methyl-2,4-pentanediol (MPD), calcium chloride and sodium acetate. It was possible to freeze the crystals directly at liquid-nitrogen temperature as the reservoir solution, which included about 30% MPD, acted as a cryoprotectant during X-ray diffraction data collection. A data set was collected from a single frozen crystal obtained using this method. The crystals belonged to space group P6322, with unit-cell parameters a = b = 448.67, c = 309.76 A and two Virus particles in the unit cell. The Virus-particle orientation was determined using a rotation function and the Virus-particle centre was estimated on the basis of crystallographic considerations. The packing of CtenRNAV in the crystal lattice was revealed by this preliminary crystallographic study.
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isolation and characterization of a single stranded RNA Virus infecting the bloom forming diatom chaetoceros socialis
Applied and Environmental Microbiology, 2009Co-Authors: Yuji Tomaru, Yoshitake Takao, Hidekazu Suzuki, Tamotsu Nagumo, Keizo NagasakiAbstract:Diatoms are very significant primary producers in the world's oceans. Various environmental factors affect the depletion of diatom populations. The importance of Viruses as a potential mortality source has recently been recognized. We isolated and characterized a new diatom Virus (Chaetoceros socialis f. radians RNA Virus [CsfrRNAV]) causing the lysis of the bloom-forming species Chaetoceros socialis Lauder f. radians (Schutt) Proschkina-Lavrenko. The Virus infectious to C. socialis f. radians was isolated from water samples collected in Hiroshima Bay. Here we show the physiology, morphology, and genome characteristics of the Virus clone. Virions were 22 nm in diameter and accumulated in the cytoplasm of the host cells. The latent period and the burst size were estimated to be <48 h and 66 infectious units per host cell, respectively. CsfrRNAV harbors a Single-Stranded RNA (ssRNA) genome and encodes at least three polypeptides of 32.0, 28.5, and 25.0 kDa. Sequencing analysis shows the length of the genome is 9,467 bases, excluding a poly(A) tail. The monophyly of CsfrRNAV and other diatom-infecting RNA Viruses, Rhizosolenia setigera RNA Virus and Chaetoceros tenuissimus RNA Virus, was strongly supported by phylogenetic analysis based on the amino acid sequence of the RNA-dependent RNA polymerase domains. This suggested a new ssRNA Virus family, BacillarioRNAviridae. This discovery of CsfrRNAV may aid in further understanding the ecological dynamics of the C. socialis f. radians population in nature and the relationships between ssRNA diatom Viruses and their hosts.
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Isolation and characterization of a Single-Stranded RNA Virus infecting the bloom-forming diatom Chaetoceros socialis.
Applied and environmental microbiology, 2009Co-Authors: Yuji Tomaru, Yoshitake Takao, Hidekazu Suzuki, Tamotsu Nagumo, Keizo NagasakiAbstract:Diatoms are very significant primary producers in the world's oceans. Various environmental factors affect the depletion of diatom populations. The importance of Viruses as a potential mortality source has recently been recognized. We isolated and characterized a new diatom Virus (Chaetoceros socialis f. radians RNA Virus [CsfrRNAV]) causing the lysis of the bloom-forming species Chaetoceros socialis Lauder f. radians (Schutt) Proschkina-Lavrenko. The Virus infectious to C. socialis f. radians was isolated from water samples collected in Hiroshima Bay. Here we show the physiology, morphology, and genome characteristics of the Virus clone. Virions were 22 nm in diameter and accumulated in the cytoplasm of the host cells. The latent period and the burst size were estimated to be
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isolation and characterization of a single stranded RNA Virus infecting the marine planktonic diatom chaetoceros tenuissimus meunier
Applied and Environmental Microbiology, 2008Co-Authors: Yoko Shirai, Yuji Tomaru, Yoshitake Takao, Hidekazu Suzuki, Tamotsu Nagumo, Keizo NagasakiAbstract:Diatoms are important components of the biological community and food web in the aquatic environment. Here, we report the characteristics of a Single-Stranded RNA (ssRNA) Virus (CtenRNAV01) that infects the marine diatom Chaetoceros tenuissimus Meunier (Bacillariophyceae). The ca. 31-nm Virus particle is icosahedral and lacks a tail. CtenRNAV01 forms crystalline arrays occupying most of the infected host's cytoplasm. By growth experiments, the lytic cycle and the burst size were estimated to be <24 h and ∼1 × 104 infectious units per host cell, respectively. Stationary-phase C. tenuissimus cultures were shown to be more sensitive to CtenRNAV01 than logarithmic-phase cultures. The most noticeable feature of this Virus is its exceptionally high yields of ∼1010 infectious units ml−1; this is much higher than those of any other algal Viruses previously characterized. CtenRNAV01 has two molecules of ssRNA of approximately 8.9 and 4.3 kb and three major proteins (33.5, 31.5, and 30.0 kDa). Sequencing of the total viral genome has produced only one large contig [9,431 bases excluding the poly(A) tail], suggesting considerable overlapping between the two RNA molecules. The monophyly of CtenRNAV01 compared to another diatom-infecting Virus, Rhizosolenia setigera RNA Virus, was strongly supported in a maximum likelihood phylogenetic tree constructed based on the concatenated amino acid sequences of the RNA-dependent RNA polymerase domains. Although further analysis is required to determine the detailed classification and nomenclature of this Virus, these data strongly suggest the existence of a diatom-infecting ssRNA Virus group in natural waters.
Yoshitake Takao - One of the best experts on this subject based on the ideXlab platform.
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Isolation and characterization of a single‐stranded RNA Virus that infects the marine planktonic diatom Chaetoceros sp. (SS08‐C03)
Phycological Research, 2012Co-Authors: Yuji Tomaru, Yoshitake Takao, Kensuke Toyoda, Kei Kimura, Kiyonari Sakurada, Natsuko Nakayama, Keizo NagasakiAbstract:Summary Diatoms are the major primary producers in the world's aquatic environment; hence, their dynamics are an important focus in current studies. Viruses, along with other physical, chemical, and biological factors, have recently been recognized as potential factors of diatom mortality. We isolated and characterized a new diatom Virus (Csp03RNAV) that causes lysis of the marine planktonic diatom Chaetoceros sp. strain SS08-C03 isolated from Hiroshima Bay, Japan. Here, we present the physiology, morphology, and genome characteristics of this Virus. Csp03RNAV was isolated from surface waters of Yatsushiro Sea, Japan. Virions were icosahedral and 32 nm in diameter, and accumulated in the cytoplasm of the host cells. The latent period was estimated to be
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isolation and characterization of a single stranded RNA Virus infecting the bloom forming diatom chaetoceros socialis
Applied and Environmental Microbiology, 2009Co-Authors: Yuji Tomaru, Yoshitake Takao, Hidekazu Suzuki, Tamotsu Nagumo, Keizo NagasakiAbstract:Diatoms are very significant primary producers in the world's oceans. Various environmental factors affect the depletion of diatom populations. The importance of Viruses as a potential mortality source has recently been recognized. We isolated and characterized a new diatom Virus (Chaetoceros socialis f. radians RNA Virus [CsfrRNAV]) causing the lysis of the bloom-forming species Chaetoceros socialis Lauder f. radians (Schutt) Proschkina-Lavrenko. The Virus infectious to C. socialis f. radians was isolated from water samples collected in Hiroshima Bay. Here we show the physiology, morphology, and genome characteristics of the Virus clone. Virions were 22 nm in diameter and accumulated in the cytoplasm of the host cells. The latent period and the burst size were estimated to be <48 h and 66 infectious units per host cell, respectively. CsfrRNAV harbors a Single-Stranded RNA (ssRNA) genome and encodes at least three polypeptides of 32.0, 28.5, and 25.0 kDa. Sequencing analysis shows the length of the genome is 9,467 bases, excluding a poly(A) tail. The monophyly of CsfrRNAV and other diatom-infecting RNA Viruses, Rhizosolenia setigera RNA Virus and Chaetoceros tenuissimus RNA Virus, was strongly supported by phylogenetic analysis based on the amino acid sequence of the RNA-dependent RNA polymerase domains. This suggested a new ssRNA Virus family, BacillarioRNAviridae. This discovery of CsfrRNAV may aid in further understanding the ecological dynamics of the C. socialis f. radians population in nature and the relationships between ssRNA diatom Viruses and their hosts.
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Isolation and characterization of a Single-Stranded RNA Virus infecting the bloom-forming diatom Chaetoceros socialis.
Applied and environmental microbiology, 2009Co-Authors: Yuji Tomaru, Yoshitake Takao, Hidekazu Suzuki, Tamotsu Nagumo, Keizo NagasakiAbstract:Diatoms are very significant primary producers in the world's oceans. Various environmental factors affect the depletion of diatom populations. The importance of Viruses as a potential mortality source has recently been recognized. We isolated and characterized a new diatom Virus (Chaetoceros socialis f. radians RNA Virus [CsfrRNAV]) causing the lysis of the bloom-forming species Chaetoceros socialis Lauder f. radians (Schutt) Proschkina-Lavrenko. The Virus infectious to C. socialis f. radians was isolated from water samples collected in Hiroshima Bay. Here we show the physiology, morphology, and genome characteristics of the Virus clone. Virions were 22 nm in diameter and accumulated in the cytoplasm of the host cells. The latent period and the burst size were estimated to be
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isolation and characterization of a single stranded RNA Virus infecting the marine planktonic diatom chaetoceros tenuissimus meunier
Applied and Environmental Microbiology, 2008Co-Authors: Yoko Shirai, Yuji Tomaru, Yoshitake Takao, Hidekazu Suzuki, Tamotsu Nagumo, Keizo NagasakiAbstract:Diatoms are important components of the biological community and food web in the aquatic environment. Here, we report the characteristics of a Single-Stranded RNA (ssRNA) Virus (CtenRNAV01) that infects the marine diatom Chaetoceros tenuissimus Meunier (Bacillariophyceae). The ca. 31-nm Virus particle is icosahedral and lacks a tail. CtenRNAV01 forms crystalline arrays occupying most of the infected host's cytoplasm. By growth experiments, the lytic cycle and the burst size were estimated to be <24 h and ∼1 × 104 infectious units per host cell, respectively. Stationary-phase C. tenuissimus cultures were shown to be more sensitive to CtenRNAV01 than logarithmic-phase cultures. The most noticeable feature of this Virus is its exceptionally high yields of ∼1010 infectious units ml−1; this is much higher than those of any other algal Viruses previously characterized. CtenRNAV01 has two molecules of ssRNA of approximately 8.9 and 4.3 kb and three major proteins (33.5, 31.5, and 30.0 kDa). Sequencing of the total viral genome has produced only one large contig [9,431 bases excluding the poly(A) tail], suggesting considerable overlapping between the two RNA molecules. The monophyly of CtenRNAV01 compared to another diatom-infecting Virus, Rhizosolenia setigera RNA Virus, was strongly supported in a maximum likelihood phylogenetic tree constructed based on the concatenated amino acid sequences of the RNA-dependent RNA polymerase domains. Although further analysis is required to determine the detailed classification and nomenclature of this Virus, these data strongly suggest the existence of a diatom-infecting ssRNA Virus group in natural waters.
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Diverse Responses of the Bivalve-Killing Dinoflagellate Heterocapsa circularisquama to Infection by a Single-Stranded RNA Virus
Applied and environmental microbiology, 2008Co-Authors: Hiroyuki Mizumoto, Yuji Tomaru, Yoshitake Takao, Yoko Shirai, Keizo NagasakiAbstract:Viruses are believed to be significant pathogens for phytoplankton. Usually, they infect a single algal species, and often their infection is highly strain specific. However, the detailed molecular background of the strain specificity and its ecological significance have not been sufficiently understood. Here, we investigated the temporal changes in viral RNA accumulation and Virus-induced cell lysis using a bloom-forming dinoflagellate Heterocapsa circularisquama and its Single-Stranded RNA Virus, HcRNAV. We observed at least three host response patterns to Virus inoculation: sensitive, resistant, and delayed lysis. In the sensitive response, the host cell culture was permissive for viral RNA replication and apparent cell lysis was observed; in contrast, resistant cell culture was nonpermissive for viral RNA replication and not lysed. In the delayed-lysis response, although viral RNA replication occurred, Virus-induced cell lysis was faint and remarkably delayed. In addition, the number of infectious Virus particles released to the culture supeRNAtant at 12 days postinoculation was comparable to that of the sensitive strain. By further analysis, a few strains were characterized as variants of the delayed-lysis strain. These observations indicate that the response of H. circularisquama to HcRNAV infection is highly diverse.
Yuji Tomaru - One of the best experts on this subject based on the ideXlab platform.
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Isolation and characterization of a single‐stranded RNA Virus that infects the marine planktonic diatom Chaetoceros sp. (SS08‐C03)
Phycological Research, 2012Co-Authors: Yuji Tomaru, Yoshitake Takao, Kensuke Toyoda, Kei Kimura, Kiyonari Sakurada, Natsuko Nakayama, Keizo NagasakiAbstract:Summary Diatoms are the major primary producers in the world's aquatic environment; hence, their dynamics are an important focus in current studies. Viruses, along with other physical, chemical, and biological factors, have recently been recognized as potential factors of diatom mortality. We isolated and characterized a new diatom Virus (Csp03RNAV) that causes lysis of the marine planktonic diatom Chaetoceros sp. strain SS08-C03 isolated from Hiroshima Bay, Japan. Here, we present the physiology, morphology, and genome characteristics of this Virus. Csp03RNAV was isolated from surface waters of Yatsushiro Sea, Japan. Virions were icosahedral and 32 nm in diameter, and accumulated in the cytoplasm of the host cells. The latent period was estimated to be
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Crystallization and preliminary X-ray analysis of a marine diatom-infecting Single-Stranded RNA Virus.
Acta Crystallographica Section F Structural Biology and Crystallization Communications, 2010Co-Authors: Hisashi Naitow, Yuji Tomaru, Yoko Shirai, Keizo NagasakiAbstract:Crystals of a diatom-infecting Virus (CtenRNAV) that diffracted to a resolution of 4.0 A were grown in a mixture of 2-methyl-2,4-pentanediol (MPD), calcium chloride and sodium acetate. It was possible to freeze the crystals directly at liquid-nitrogen temperature as the reservoir solution, which included about 30% MPD, acted as a cryoprotectant during X-ray diffraction data collection. A data set was collected from a single frozen crystal obtained using this method. The crystals belonged to space group P6322, with unit-cell parameters a = b = 448.67, c = 309.76 A and two Virus particles in the unit cell. The Virus-particle orientation was determined using a rotation function and the Virus-particle centre was estimated on the basis of crystallographic considerations. The packing of CtenRNAV in the crystal lattice was revealed by this preliminary crystallographic study.
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isolation and characterization of a single stranded RNA Virus infecting the bloom forming diatom chaetoceros socialis
Applied and Environmental Microbiology, 2009Co-Authors: Yuji Tomaru, Yoshitake Takao, Hidekazu Suzuki, Tamotsu Nagumo, Keizo NagasakiAbstract:Diatoms are very significant primary producers in the world's oceans. Various environmental factors affect the depletion of diatom populations. The importance of Viruses as a potential mortality source has recently been recognized. We isolated and characterized a new diatom Virus (Chaetoceros socialis f. radians RNA Virus [CsfrRNAV]) causing the lysis of the bloom-forming species Chaetoceros socialis Lauder f. radians (Schutt) Proschkina-Lavrenko. The Virus infectious to C. socialis f. radians was isolated from water samples collected in Hiroshima Bay. Here we show the physiology, morphology, and genome characteristics of the Virus clone. Virions were 22 nm in diameter and accumulated in the cytoplasm of the host cells. The latent period and the burst size were estimated to be <48 h and 66 infectious units per host cell, respectively. CsfrRNAV harbors a Single-Stranded RNA (ssRNA) genome and encodes at least three polypeptides of 32.0, 28.5, and 25.0 kDa. Sequencing analysis shows the length of the genome is 9,467 bases, excluding a poly(A) tail. The monophyly of CsfrRNAV and other diatom-infecting RNA Viruses, Rhizosolenia setigera RNA Virus and Chaetoceros tenuissimus RNA Virus, was strongly supported by phylogenetic analysis based on the amino acid sequence of the RNA-dependent RNA polymerase domains. This suggested a new ssRNA Virus family, BacillarioRNAviridae. This discovery of CsfrRNAV may aid in further understanding the ecological dynamics of the C. socialis f. radians population in nature and the relationships between ssRNA diatom Viruses and their hosts.
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Isolation and characterization of a Single-Stranded RNA Virus infecting the bloom-forming diatom Chaetoceros socialis.
Applied and environmental microbiology, 2009Co-Authors: Yuji Tomaru, Yoshitake Takao, Hidekazu Suzuki, Tamotsu Nagumo, Keizo NagasakiAbstract:Diatoms are very significant primary producers in the world's oceans. Various environmental factors affect the depletion of diatom populations. The importance of Viruses as a potential mortality source has recently been recognized. We isolated and characterized a new diatom Virus (Chaetoceros socialis f. radians RNA Virus [CsfrRNAV]) causing the lysis of the bloom-forming species Chaetoceros socialis Lauder f. radians (Schutt) Proschkina-Lavrenko. The Virus infectious to C. socialis f. radians was isolated from water samples collected in Hiroshima Bay. Here we show the physiology, morphology, and genome characteristics of the Virus clone. Virions were 22 nm in diameter and accumulated in the cytoplasm of the host cells. The latent period and the burst size were estimated to be
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isolation and characterization of a single stranded RNA Virus infecting the marine planktonic diatom chaetoceros tenuissimus meunier
Applied and Environmental Microbiology, 2008Co-Authors: Yoko Shirai, Yuji Tomaru, Yoshitake Takao, Hidekazu Suzuki, Tamotsu Nagumo, Keizo NagasakiAbstract:Diatoms are important components of the biological community and food web in the aquatic environment. Here, we report the characteristics of a Single-Stranded RNA (ssRNA) Virus (CtenRNAV01) that infects the marine diatom Chaetoceros tenuissimus Meunier (Bacillariophyceae). The ca. 31-nm Virus particle is icosahedral and lacks a tail. CtenRNAV01 forms crystalline arrays occupying most of the infected host's cytoplasm. By growth experiments, the lytic cycle and the burst size were estimated to be <24 h and ∼1 × 104 infectious units per host cell, respectively. Stationary-phase C. tenuissimus cultures were shown to be more sensitive to CtenRNAV01 than logarithmic-phase cultures. The most noticeable feature of this Virus is its exceptionally high yields of ∼1010 infectious units ml−1; this is much higher than those of any other algal Viruses previously characterized. CtenRNAV01 has two molecules of ssRNA of approximately 8.9 and 4.3 kb and three major proteins (33.5, 31.5, and 30.0 kDa). Sequencing of the total viral genome has produced only one large contig [9,431 bases excluding the poly(A) tail], suggesting considerable overlapping between the two RNA molecules. The monophyly of CtenRNAV01 compared to another diatom-infecting Virus, Rhizosolenia setigera RNA Virus, was strongly supported in a maximum likelihood phylogenetic tree constructed based on the concatenated amino acid sequences of the RNA-dependent RNA polymerase domains. Although further analysis is required to determine the detailed classification and nomenclature of this Virus, these data strongly suggest the existence of a diatom-infecting ssRNA Virus group in natural waters.
Qi Jiancheng - One of the best experts on this subject based on the ideXlab platform.
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Computational Simulation of Studying Zika Virus: from Macroscale to Nanoscale
DEStech Transactions on Computer Science and Engineering, 2018Co-Authors: Xiu Guo Zhao, Wu Jinhui, Du Yaohua, Li-mei Hao, Hu Mingxi, Xu Xinxi, Yi Ying, Zong Xing Zhang, Qi JianchengAbstract:Zika Virus (ZIKV) recently outbreaking from 2015 to 2016 over Americas has attracted a global health concern. As a member of family of Flaviviridae, Zika Virus a positive-sense Single-Stranded RNA Virus is highly likely associated with birth defects (primary microcephaly) and neurological complications. However, computer simulation method is widely used to study spread of Zika Virus at macroscale level and related-structures and vaccines of Zika Virus at atomic level, which also provides insights into Zika Virus. Here the current advancements were reviewed and future developments were discussed.
Yoko Shirai - One of the best experts on this subject based on the ideXlab platform.
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Crystallization and preliminary X-ray analysis of a marine diatom-infecting Single-Stranded RNA Virus.
Acta Crystallographica Section F Structural Biology and Crystallization Communications, 2010Co-Authors: Hisashi Naitow, Yuji Tomaru, Yoko Shirai, Keizo NagasakiAbstract:Crystals of a diatom-infecting Virus (CtenRNAV) that diffracted to a resolution of 4.0 A were grown in a mixture of 2-methyl-2,4-pentanediol (MPD), calcium chloride and sodium acetate. It was possible to freeze the crystals directly at liquid-nitrogen temperature as the reservoir solution, which included about 30% MPD, acted as a cryoprotectant during X-ray diffraction data collection. A data set was collected from a single frozen crystal obtained using this method. The crystals belonged to space group P6322, with unit-cell parameters a = b = 448.67, c = 309.76 A and two Virus particles in the unit cell. The Virus-particle orientation was determined using a rotation function and the Virus-particle centre was estimated on the basis of crystallographic considerations. The packing of CtenRNAV in the crystal lattice was revealed by this preliminary crystallographic study.
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isolation and characterization of a single stranded RNA Virus infecting the marine planktonic diatom chaetoceros tenuissimus meunier
Applied and Environmental Microbiology, 2008Co-Authors: Yoko Shirai, Yuji Tomaru, Yoshitake Takao, Hidekazu Suzuki, Tamotsu Nagumo, Keizo NagasakiAbstract:Diatoms are important components of the biological community and food web in the aquatic environment. Here, we report the characteristics of a Single-Stranded RNA (ssRNA) Virus (CtenRNAV01) that infects the marine diatom Chaetoceros tenuissimus Meunier (Bacillariophyceae). The ca. 31-nm Virus particle is icosahedral and lacks a tail. CtenRNAV01 forms crystalline arrays occupying most of the infected host's cytoplasm. By growth experiments, the lytic cycle and the burst size were estimated to be <24 h and ∼1 × 104 infectious units per host cell, respectively. Stationary-phase C. tenuissimus cultures were shown to be more sensitive to CtenRNAV01 than logarithmic-phase cultures. The most noticeable feature of this Virus is its exceptionally high yields of ∼1010 infectious units ml−1; this is much higher than those of any other algal Viruses previously characterized. CtenRNAV01 has two molecules of ssRNA of approximately 8.9 and 4.3 kb and three major proteins (33.5, 31.5, and 30.0 kDa). Sequencing of the total viral genome has produced only one large contig [9,431 bases excluding the poly(A) tail], suggesting considerable overlapping between the two RNA molecules. The monophyly of CtenRNAV01 compared to another diatom-infecting Virus, Rhizosolenia setigera RNA Virus, was strongly supported in a maximum likelihood phylogenetic tree constructed based on the concatenated amino acid sequences of the RNA-dependent RNA polymerase domains. Although further analysis is required to determine the detailed classification and nomenclature of this Virus, these data strongly suggest the existence of a diatom-infecting ssRNA Virus group in natural waters.
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Diverse Responses of the Bivalve-Killing Dinoflagellate Heterocapsa circularisquama to Infection by a Single-Stranded RNA Virus
Applied and environmental microbiology, 2008Co-Authors: Hiroyuki Mizumoto, Yuji Tomaru, Yoshitake Takao, Yoko Shirai, Keizo NagasakiAbstract:Viruses are believed to be significant pathogens for phytoplankton. Usually, they infect a single algal species, and often their infection is highly strain specific. However, the detailed molecular background of the strain specificity and its ecological significance have not been sufficiently understood. Here, we investigated the temporal changes in viral RNA accumulation and Virus-induced cell lysis using a bloom-forming dinoflagellate Heterocapsa circularisquama and its Single-Stranded RNA Virus, HcRNAV. We observed at least three host response patterns to Virus inoculation: sensitive, resistant, and delayed lysis. In the sensitive response, the host cell culture was permissive for viral RNA replication and apparent cell lysis was observed; in contrast, resistant cell culture was nonpermissive for viral RNA replication and not lysed. In the delayed-lysis response, although viral RNA replication occurred, Virus-induced cell lysis was faint and remarkably delayed. In addition, the number of infectious Virus particles released to the culture supeRNAtant at 12 days postinoculation was comparable to that of the sensitive strain. By further analysis, a few strains were characterized as variants of the delayed-lysis strain. These observations indicate that the response of H. circularisquama to HcRNAV infection is highly diverse.
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Genomic and phylogenetic analysis of a Single-Stranded RNA Virus infecting Rhizosolenia setigera (Stramenopiles: Bacillariophyceae)
Journal of the Marine Biological Association of the United Kingdom, 2006Co-Authors: Yoko Shirai, Hiroyuki Mizumoto, Yuji Tomaru, Yoshitake Takao, Daiske Honda, Keizo NagasakiAbstract:We report the first complete genome sequence of the marine diatom-infecting, positive-sense Single-Stranded RNA (ssRNA) Virus, Rhizosolenia setigera RNA Virus (RsRNAV). The genome is 8877 nucleotides (nt), polyadenylated, lacking a cap structure, and has two large open reading frames (ORFs): ORF-1 (4818 nt), a polyprotein gene coding for replicases, e.g. RNA helicase, RNA-dependent RNA polymerase (RdRp); and ORF-2 (2883 nt), a polyprotein gene coding for structural proteins. The ORFs are separated by a 323 nt intergenic region (IGR), flanked by a 624 nt 5′-untranslated region (UTR) and a 229 nt 3′-UTR. The deduced amino acid sequences for ORF-1 and ORF-2 respectively show considerable similarities to the non-structural and structural proteins of a marine raphidophyte-infecting Virus HaRNAV ( Heterosigma akashiwo RNA Virus). Phylogenetic analyses of concatenated amino acid sequences of RNA helicase and RdRp domains supported the monophyly of RsRNAV, HaRNAV and a marine protist-infecting Virus SssRNAV ( Schizochytrium Single-Stranded RNA Virus) with moderate bootstrap values of 79–83%, but not at the family level, whilst their monophyly was only weakly supported (50–55%) in the phylogenetic tree based on RdRp whole domain. As a result, comparison of the genome organization and sequence suggests RsRNAV is not a member of any currently defined Virus family. In the RdRp tree, the positive-sense ssRNA Viruses infecting Stramenopiles (RsRNAV, HaRNAV and SssRNAV) and Alveolata (HcRNAV ( Heterocapsa circularisquama RNA Virus)) were categorized into phylogenetically distant clades, which suggests a host/Virus coevolution. Our study supports the hypothesis that a diverse array of ssRNA Viruses exists in marine environments.
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isolation and characterization of two distinct types of hcRNAv a single stranded RNA Virus infecting the bivalve killing microalga heterocapsa circularisquama
Aquatic Microbial Ecology, 2004Co-Authors: Yuji Tomaru, Yoko Shirai, Noriaki Katanozaka, Kensho Nishida, Kenji Tarutani, Mineo Yamaguchi, Keizo NagasakiAbstract:HcRNAV, a novel Single-Stranded RNA (ssRNA) Virus specifically infecting the bivalve- killing dinoflagellate Heterocapsa circularisquama, was isolated from the coastal waters of Japan. HcRNAV strains were divided into 2 types based on intra-species host-range tests. The 2 types showed complementary strain-specific infectivity. In the following experiments, typical strains of each type (HcRNAV34 and HcRNAV109), were characterized. Both Virus strains were icosahedral, ca. 30 nm in diameter, and harbored a single molecule of ssRNA approximately 4.4 kb in size. Thus, in morphology and nucleic acid type, HcRNAV is distinct from HcV, the previously reported large double-stranded DNA Virus infecting H. circularisquama. Virus particles appeared in the cytoplasm of the host cells within 24 h post-infection, and crystalline arrays or unordered aggregations of Virus particles were observed. The burst size and latent period were estimated at 3.4 × 10 3 to 2.1 × 10 4 infec- tious particles cell -1 and 24 to 48 h, respectively. To our knowledge, this is the first report of a ssRNA Virus infecting dinoflagellates that has been isolated and maintained in culture. Although HcRNAV is considered to have some similarities with plant Viruses belonging to genera SobemoVirus and LuteoVirus, further genomic analysis is required to discuss the detailed classification and nomencla- ture of HcRNAV. The finding of RNA Viruses infecting microalgae such as HaRNAV (Heterosigma akashiwo RNA Virus) and HcRNAV emphasizes the diversity of algicidal viral pathogens.
