Dataset Information

Mutation patterns of mitochondrial H- and L-strand DNA in closely related Cyprinid fishes.

ABSTRACT: Mitochondrial genome replication is asymmetric. Replication starts from the origin of heavy (H)-strand replication, displacing the parental H-strand as it proceeds along the molecule. The H-strand remains single stranded until light (L)-strand replication is initiated from a second origin of replication. It has been suggested that single-stranded H-strand DNA is more sensitive to mutational damage, giving rise to substitutional rate differences between the two strands and among genes in mammalian mitochondrial DNA. In this study, we analyzed sequences of the cytochrome b, ND4, ND4L, and COI genes of cyprinid fishes to investigate rates and patterns of nucleotide substitution in the mitochondrial genome. To test for strand-asymmetric mutation pressure, a likelihood-ratio test was developed and applied to the cyprinid sequences. Patterns of substitution and levels of strand-asymmetric mutation pressure were largely consistent with a mutation gradient between the H- and L-strand origins of replication. Significant strand bias was observed among rates of transitional substitution. However, biological interpretation of the direction and strength of strand asymmetry for specific classes of substitutions is problematic. The problem occurs because the rate of any single class of substitution inferred from one strand is actually a sum of rates on two strands. The validity of the likelihood-ratio test is not affected by this problem.

SUBMITTER: Bielawski JP

PROVIDER: S-EPMC1462211 | biostudies-other | 2002 Aug

REPOSITORIES: biostudies-other

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Mutation patterns of mitochondrial H- and L-strand DNA in closely related Cyprinid fishes.

Bielawski Joseph P JP Gold John R JR

Genetics 20020801 4

Mitochondrial genome replication is asymmetric. Replication starts from the origin of heavy (H)-strand replication, displacing the parental H-strand as it proceeds along the molecule. The H-strand remains single stranded until light (L)-strand replication is initiated from a second origin of replication. It has been suggested that single-stranded H-strand DNA is more sensitive to mutational damage, giving rise to substitutional rate differences between the two strands and among genes in mammalia ...[more]

PMID: 12583346

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Project description:BackgroundPoorly regulated international trade in ornamental fishes poses risks to both biodiversity and economic activity via invasive alien species and exotic pathogens. Border security officials need robust tools to confirm identifications, often requiring hard-to-obtain taxonomic literature and expertise. DNA barcoding offers a potentially attractive tool for quarantine inspection, but has yet to be scrutinised for aquarium fishes. Here, we present a barcoding approach for ornamental cyprinid fishes by: (1) expanding current barcode reference libraries; (2) assessing barcode congruence with morphological identifications under numerous scenarios (e.g. inclusion of GenBank data, presence of singleton species, choice of analytical method); and (3) providing supplementary information to identify difficult species.Methodology/principal findingsWe sampled 172 ornamental cyprinid fish species from the international trade, and provide data for 91 species currently unrepresented in reference libraries (GenBank/Bold). DNA barcodes were found to be highly congruent with our morphological assignments, achieving success rates of 90-99%, depending on the method used (neighbour-joining monophyly, bootstrap, nearest neighbour, GMYC, percent threshold). Inclusion of data from GenBank (additional 157 spp.) resulted in a more comprehensive library, but at a cost to success rate due to the increased number of singleton species. In addition to DNA barcodes, our study also provides supporting data in the form of specimen images, morphological characters, taxonomic bibliography, preserved vouchers, and nuclear rhodopsin sequences. Using this nuclear rhodopsin data we also uncovered evidence of interspecific hybridisation, and highlighted unrecognised diversity within popular aquarium species, including the endangered Indian barb Puntius denisonii.Conclusions/significanceWe demonstrate that DNA barcoding provides a highly effective biosecurity tool for rapidly identifying ornamental fishes. In cases where DNA barcodes are unable to offer an identification, we improve on previous studies by consolidating supplementary information from multiple data sources, and empower biosecurity agencies to confidently identify high-risk fishes in the aquarium trade.

Dataset Information

Mutation patterns of mitochondrial H- and L-strand DNA in closely related Cyprinid fishes.

Publications

Mutation patterns of mitochondrial H- and L-strand DNA in closely related Cyprinid fishes.

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