Project description:Swertia tetraptera, native to the Qinghai-Tibetan Plateau, is an important traditional Chinese medicine. Although researchers have done a lot of work on it, the phylogenetic position of S. tetraptera within Swertia has still not been solved. Chloroplast genome sequences play a significant role in the development of molecular markers in plant phylogenetic and population genetic studies. In present study, we determined the complete chloroplast genome sequences for S. tetraptera using IIumina sequencing. The total length of the complete chloroplast genome of S. tetraptera is 152,840 bp, of which the GC content is 37.95%. The genome encodes 130 functional genes, including 85 protein-coding genes, 37 tRNA, and 8 rRNA. Phylogenetic analysis suggested that S. tetraptera forms monophyletic group with Halenia corniculata which shows closed relationship with the Halenia.
Project description:BackgroundClimate fluctuations during the Pleistocene and mountain uplift are vital driving forces affecting geographic distribution. Here, we ask how an annual plant responded to the Pleistocene glacial cycles.MethodsIn this study, we analyzed the population demographic history of the annual herb Swertia tetraptera Maxim (Gentianaceae) endemic to Qinghai-Tibetan Plateau (QTP). A total of 301 individuals from 35 populations of S. tetraptera were analyzed based on two maternally inherited chloroplast fragments (trnL-trnF and trnS-trnG). Phylogeographic analysis was combined with species distribution modeling to detect the genetic variations in S. tetraptera.ResultsThe genetic diversity of S. tetraptera was high, likely due to its wide natural range, high proportion of endemic haplotypes and evolutionary history. Fifty-four haplotypes were identified in S. tetraptera. Only a few haplotypes were widespread (Hap_4, Hap_1, Hap_3), which were dispersed throughout the present geographical range of S. tetraptera, while many haplotypes were confined to single populations. The cpDNA dataset showed that phylogeographic structuring was lacking across the distribution range of S. tetraptera. Analyses of molecular variance showed that most genetic variation was found within populations (70.51%). In addition, the relationships of the haplotypes were almost completely unresolved by phylogenetic reconstruction. Both mismatch distribution analysis and neutrality tests showed a recent expansion across the distribution range of S. tetraptera. The MaxEnt analysis showed that S. tetraptera had a narrow distribution range during the Last Glacial Maximum (LGM) and a wide distribution range during the current time, with predictions into the future showing the distribution range of S. tetraptera expanding.ConclusionOur study implies that the current geographic and genetic distribution of S. tetraptera is likely to have been shaped by Quaternary periods. Multiple microrefugia of S. tetraptera existed during Quaternary glaciations. Rapid intraspecific diversification and hybridization and/or introgression may have played a vital role in shaping the current distribution patterns of S. tetraptera. The distribution range of S. tetraptera appeared to have experienced contraction during the LGM; in the future, when the global climate becomes warmer with rising carbon dioxide levels, the distribution of S. tetraptera will expand.
Project description:BackgroundAspiculuris tetraptera, as a parasitic pinworm, is most frequently detected in laboratory mice, and transmission is mediated by the eggs contained in the faeces of infected mice. A highly sensitive and quantitative faeces-based diagnostic tool would be useful for the early detection of A. tetraptera to inhibit the expansion of infection. In this study, we developed a quantitative assay that exhibits high sensitivity in detecting A. tetraptera in faeces using PCR techniques.ResultsEndpoint PCR demonstrated the detection of A. tetraptera DNA in 0.5 ng genomic DNA extracted from the faeces of infected mice. To quantitatively detect the small amount of A. tetraptera DNA, locked nucleic acid (LNA)-based primers and LNA-based TaqMan probes were used for the quantitative PCR assay (qPCR). The combination of LNA-based DNA increased detection sensitivity by more than 100-fold compared to using normal oligo DNAs. The copy number of the A. tetraptera DNA detected was positively related to the infected faeces-derived genomic DNA with a simple linearity regression in the range of 20 pg to 15 ng of the genomic DNA. To more conveniently detect infection using faeces, the LNA-based TaqMan assay was applied to the crude fraction of the faeces without DNA purification. An assay using ethanol precipitation of the faeces yielded results consistent with those of direct microscopic observation.ConclusionThe LNA-TaqMan assay developed in this study quantitatively detects A. tetraptera infection in mouse faeces.
Project description:Aspiculuris tetraptera a pinworm of mice, is an important parasite in institutions with mice colonies for both research and teaching purposes. Infection with this parasite has impact on biomedical research. This is likely due to the availability of the parasite's eggs in the environment, therefore can easily be transmitted and infection is generally asymptomatic. No information regarding the prevalence, morphology or phylogeny is available on A. tetraptera from Saudi Arabia. A group of 50 laboratory mice were investigated for the presence of A. tetraptera. Worms were described morphologically and molecular characterization was attempted using 18S rRNA and Cytochrome Oxidase Subunit I genes. The prevalence of A. tetraptera infestation in the laboratory mice examined was found to be 46%. Morphological description indicated that the worms belong to A. tetraptera and this was confirmed by molecular characterization. Both regions studied have shown that the worm under investigation grouped with A. tetraptera. 18S rDNA sequences obtained in the present study showed high identity with sequences from A. tetraptera while Cytochrome c Oxidase subunit I gene (COI) sequences showed intraspecific variation resulted into two haplotypes from the isolates in the present study. A. tetraptera was recorded for the first time from Saudi Arabia. Molecular characterization has shown, based on the COI sequences, that the Saudi isolates of A. tetraptera are distinct.