Genetic variability of microcystin biosynthesis genes in Planktothrix as elucidated from samples preserved by heat desiccation during three decades.
Historic samples of phytoplankton can provide information on the abundance of the toxigenic genotypes of cyanobacteria in dependence on increased or decreased eutrophication. The analysis of a time-series from preserved phytoplankton samples by quantitative PCR (qPCR) extends observation periods con...
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2013-01-01
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| Online Access: | https://doi.org/10.1371/journal.pone.0080177 |
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| author | Veronika Ostermaier Guntram Christiansen Ferdinand Schanz Rainer Kurmayer |
| author_facet | Veronika Ostermaier Guntram Christiansen Ferdinand Schanz Rainer Kurmayer |
| author_sort | Veronika Ostermaier |
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| description | Historic samples of phytoplankton can provide information on the abundance of the toxigenic genotypes of cyanobacteria in dependence on increased or decreased eutrophication. The analysis of a time-series from preserved phytoplankton samples by quantitative PCR (qPCR) extends observation periods considerably. The analysis of DNA from heat-desiccated samples by qPCR can be aggravated by point substitutions or the fragmentation of DNA introduced by the high temperature. In this study, we analyzed whether the heat desiccation of the cellular material of the cyanobacterium Planktothrix sp. introduced potential errors to the template DNA that is used for qPCR within (i) 16S rDNA and phycocyanin genes and (ii) the mcyA gene indicative of the incorporation of either dehydrobutyrine (Dhb) or N-methyl-dehydroalanine (Mdha) in position 7, and (ii) the mcyB gene, which is indicative of homotyrosine (Hty) in position 2 of the microcystin (MC) molecule. Due to high temperature desiccation, the deterioration of the DNA template quality was rather due to fragmentation than due to nucleotide substitutions. By using the heat-desiccated samples of Lake Zürich, Switzerland the abundance of the Dhb, Mdha and Hty genotypes was determined during three decades (1977-2008). Despite major changes in the trophic state of the lake resulting in a major increase of the total Planktothrix population density, the proportion of these genotypes encoding the synthesis of different MC congeners showed high stability. Nevertheless, a decline of the most abundant mcyA genotype indicative of the synthesis of Dhb in position 7 of the MC molecule was observed. This decline could be related to the gradual incline in the proportion of a mutant genotype carrying a 1.8kbp deletion of this gene region. The increase of this mcyA (Dhb) gene deletion mutant has been minor so far, however, and likely did not affect the overall toxicity of the population. |
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| language | English |
| publishDate | 2013-01-01 |
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| spelling | doaj-art-67c36a0214ac49af9679eba35f9119782025-08-20T02:34:14ZengPublic Library of Science (PLoS)PLoS ONE1932-62032013-01-01811e8017710.1371/journal.pone.0080177Genetic variability of microcystin biosynthesis genes in Planktothrix as elucidated from samples preserved by heat desiccation during three decades.Veronika OstermaierGuntram ChristiansenFerdinand SchanzRainer KurmayerHistoric samples of phytoplankton can provide information on the abundance of the toxigenic genotypes of cyanobacteria in dependence on increased or decreased eutrophication. The analysis of a time-series from preserved phytoplankton samples by quantitative PCR (qPCR) extends observation periods considerably. The analysis of DNA from heat-desiccated samples by qPCR can be aggravated by point substitutions or the fragmentation of DNA introduced by the high temperature. In this study, we analyzed whether the heat desiccation of the cellular material of the cyanobacterium Planktothrix sp. introduced potential errors to the template DNA that is used for qPCR within (i) 16S rDNA and phycocyanin genes and (ii) the mcyA gene indicative of the incorporation of either dehydrobutyrine (Dhb) or N-methyl-dehydroalanine (Mdha) in position 7, and (ii) the mcyB gene, which is indicative of homotyrosine (Hty) in position 2 of the microcystin (MC) molecule. Due to high temperature desiccation, the deterioration of the DNA template quality was rather due to fragmentation than due to nucleotide substitutions. By using the heat-desiccated samples of Lake Zürich, Switzerland the abundance of the Dhb, Mdha and Hty genotypes was determined during three decades (1977-2008). Despite major changes in the trophic state of the lake resulting in a major increase of the total Planktothrix population density, the proportion of these genotypes encoding the synthesis of different MC congeners showed high stability. Nevertheless, a decline of the most abundant mcyA genotype indicative of the synthesis of Dhb in position 7 of the MC molecule was observed. This decline could be related to the gradual incline in the proportion of a mutant genotype carrying a 1.8kbp deletion of this gene region. The increase of this mcyA (Dhb) gene deletion mutant has been minor so far, however, and likely did not affect the overall toxicity of the population.https://doi.org/10.1371/journal.pone.0080177 |
| spellingShingle | Veronika Ostermaier Guntram Christiansen Ferdinand Schanz Rainer Kurmayer Genetic variability of microcystin biosynthesis genes in Planktothrix as elucidated from samples preserved by heat desiccation during three decades. PLoS ONE |
| title | Genetic variability of microcystin biosynthesis genes in Planktothrix as elucidated from samples preserved by heat desiccation during three decades. |
| title_full | Genetic variability of microcystin biosynthesis genes in Planktothrix as elucidated from samples preserved by heat desiccation during three decades. |
| title_fullStr | Genetic variability of microcystin biosynthesis genes in Planktothrix as elucidated from samples preserved by heat desiccation during three decades. |
| title_full_unstemmed | Genetic variability of microcystin biosynthesis genes in Planktothrix as elucidated from samples preserved by heat desiccation during three decades. |
| title_short | Genetic variability of microcystin biosynthesis genes in Planktothrix as elucidated from samples preserved by heat desiccation during three decades. |
| title_sort | genetic variability of microcystin biosynthesis genes in planktothrix as elucidated from samples preserved by heat desiccation during three decades |
| url | https://doi.org/10.1371/journal.pone.0080177 |
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