Isolation and characterization of a virus (CvV-BW1) that infects symbiotic algae of Paramecium bursaria in Lake Biwa, Japan

<p>Abstract</p> <p>Background</p> <p>We performed an environmental study of viruses infecting the symbiotic single-celled algae of <it>Paramecium bursaria </it>(<it>Paramecium bursaria Chlorella </it>virus, PBCV) in Lake Biwa, the largest lake in Japan. The viruses detected were all <it>Chlorella variabilis </it>virus (CvV = NC64A virus). One of them, designated CvV-BW1, was subjected to further characterization.</p> <p>Results</p> <p>CvV-BW1 formed small plaques and had a linear DNA genome of 370 kb, as judged by pulsed-field gel electrophoresis. Restriction analysis indicated that CvV-BW1 DNA belongs to group H, one of the most resistant groups among CvV DNAs. Based on a phylogenetic tree constructed using the <it>dnapol </it>gene, CvV was classified into two clades, A and B. CvV-BW1 belonged to clade B, in contrast to all previously identified virus strains of group H that belonged to clade A.</p> <p>Conclusions</p> <p>We conclude that CvV-BW1 composes a distinct species within <it>C. variabilis </it>virus.</p

Monitoring of Environmental Ionizing Radiation and Radioisotopes in Okayama City and the Vicinty (II) - An estimation of the external radiation from the environmental radiation dose -

Monitoring of environmental ionizing radiation and radioisotopes in Okayama city and the vicinity was carried out from the point of view of the external radiation from the environmental radiation dose. Although the fluctuation of monthly detected radiation dose throughout the year was rather low at each observation point, the mean value of dose equivalent was varied between the place of observation. From the observation of the distribution of environmental radiation dose in Okayama city, it was assumed that its distribution was well corresponded with the distribution of igneous rocks. The concentrations of radioisotopes in various kinds of rocks corrected in Okayama city and its vicinity were determined. It became apparent that high concentrations of radioisotopes, such as (134)Cs, (40)K, (226)Ra and (228)Th, were detected in igneous rocks, such as granite, gabbro and rhyolitic tuff, although the contents in sedimentary rocks, such as pelite, schist, psammite and limestone, were rather low. This result was in good agreement with that of the distribution of radiation dose in Okayama city

Transcriptional regulation of Saccharomyces cerevisiaeCYS3 encoding cystathionine γ-lyase

In studying the regulation of GSH11, the structural gene of the high-affinity glutathione transporter (GSH-P1) in Saccharomyces cerevisiae, a cis-acting cysteine responsive element, CCGCCACAC (CCG motif), was detected. Like GSH-P1, the cystathionine γ-lyase encoded by CYS3 is induced by sulfur starvation and repressed by addition of cysteine to the growth medium. We detected a CCG motif (−311 to −303) and a CGC motif (CGCCACAC; −193 to −186), which is one base shorter than the CCG motif, in the 5′-upstream region of CYS3. One copy of the centromere determining element 1, CDE1 (TCACGTGA; −217 to −210), being responsible for regulation of the sulfate assimilation pathway genes, was also detected. We tested the roles of these three elements in the regulation of CYS3. Using a lacZ-reporter assay system, we found that the CCG/CGC motif is required for activation of CYS3, as well as for its repression by cysteine. In contrast, the CDE1 motif was responsible for only activation of CYS3. We also found that two transcription factors, Met4 and VDE, are responsible for activation of CYS3 through the CCG/CGC and CDE1 motifs. These observations suggest a dual regulation of CYS3 by factors that interact with the CDE1 motif and the CCG/CGC motifs

Patterns of genetic and phenotypic suppression of lys2 mutations in the yeast saccharomyces cervisiae

A total of 358 lys2 mutants of Saccharomyces cerevisiae have been characterized for suppressibility by the following suppressors: UAA and UAG suppressors that insert tyrosine, serine or leucine; a putative UGA suppressor; an omnipotent suppressor SUP46; and a frameshift suppressor SUFI-1. In addition, the lys2 mutants were examined for phenotypic suppression by the aminoglycoside antibiotic paromomycin, for osmotic remediability and for temperature sensitivity. The mutants exhibited over 50 different patterns of suppression and most of the nonsense mutants appeared similar to nonsense mutants previously described. A total of 24% were suppressible by one or more of the UAA suppressors, 4% were suppressible by one or more of the UAG suppressors, while only one was suppressible by the UGA suppressor and only one was weakly suppressible by the frameshift suppressor. One mutant responded to both UAA and UAG suppressors, indicating that UAA or UAG mutations at certain rare sites can be exceptions to the specific action of UAA and UAG suppressors. Some of the mutants appeared to require certain types of amino acid replacements at the mutant sites in order to produce a functional gene product, while others appeared to require suppressors that were expressed at high levels. Many of the mutants suppressible by SUP46 and paromomycin were not suppressible by any of the UAA, UAG or UGA suppressors, indicating that omnipotent suppression and phenotypic suppression need not be restricted to nonsense mutations. All of the mutants suppressible by SUP46 were also suppressible by paromomycin, suggesting a common mode of action of omnipotent suppression and phenotypic misreading