Glutathione S-transferases are important detoxification enzymes involved in insecticide resistance. Sequencing the Tribolium castaneum genome provides an opportunity to investigate the structure, function, and evolution of GSTs on a genome-wide scale. Thirty-six putative cytosolic GSTs and 5 microsomal GSTs have been identified in T. castaneum. Furthermore, 40, 35, 13, 23, and 32 GSTs have been discovered the other insects, Drosophila, Anopheles, Apis, Bombyx, and Acyrthosiphon, respectively. Phylogenetic analyses reveal that insect-specific GSTs, Epsilon and Delta, are the largest species-specific expanded GSTs. In T. castaneum, most GSTs are tandemly arranged in three chromosomes. Particularly, Epsilon GSTs have an inverted long-fragment duplication in the genome. Other four widely distributed classes are highly conserved in all species. Given that GSTs specially expanded in Tribolium castaneum, these genes might help to resist poisonous chemical environments and produce resistance to kinds of different insecticides.
The Qinghai-Tibetan Plateau is one of the most extensive habitats for alpine plants in the world. Therefore, the patterns of genetic variation in populations on the Plateau can reveal the detailed demographic history of alpine plants. We analysed the geographical structure of chloroplast matK sequence variation in Potentilla fruticosa L. (Rosaceae), a shrub currently found across the entire Plateau. We obtained sequence data from 508 individuals from 23 populations at sites ranging from the high-altitude interior to the relatively low-altitude northeastern Plateau. In the interior region, genetic diversity was high and included ancestral haplotypes. In contrast, northeastern populations were characterized by relatively low genetic diversity and recently derived haplotypes. The estimated expansion time in the interior population was 17 times that in the northeastern population. These data suggest that P. fruticosa expanded its range on the Plateau during periods of climatic cooling and contracted to the interior region during warmer periods. Thus, the interior region acted as a refugium and greatly contributed to the diversification of P. fruticosa.
Dendrobium officinale is a critically endangered perennial herb endemic to China. Determining the levels of genetic diversity and patterns of population genetic structure of this species would assist in its conservation and management. Data of 12 populations were used to assess its genetic diversity and population structure, employing the method of amplified fragment length polymorphism (AFLP). A high level of genetic diversity was detected (H (E) = 0.269) with POPGENE. As revealed by AMOVA analysis, there was moderate variation between pairs of populations with Phi(ST) values ranging from 0.047 to 0.578 and on average 26.97% of the genetic variation occurred among populations. Three main clusters were shown in UPGMA dendrogram using TFPGA, which is consistent with the result of principal coordinate ananlysis (PCO) using NTSYS. Keeping a stable environment is critical for the in situ conservation and management of this rare and endangered plant, and for ex situ conservation it is important to design an integrated germplasm bank.
Heat-shock protein 90 (HSP90) is a highly conserved molecular chaperone found in all species except for Archaea, which is required not only for stress tolerance but also for normal development. Recently, it was reported that HSP83, one member of the cytosolic HSP90 family, contributes to oogenesis and responds to heat resistance in Tribolium castaneum. Here, a novel ER-based HSP90 gene, Tchsp90, has been identified in T. castaneum. Phylogenetic analysis showed that hsp90s and hsp83s evolved separately from a common ancestor but that hsp90s originated earlier. Quantitative real-time polymerase chain reaction illustrated that Tchsp90 is expressed in all developmental stages and is highly expressed at early pupa and late adult stages. Tchsp90 was upregulated in response to heat stress but not to cold stress. Laval RNAi revealed that Tchsp90 is important for larval/ pupal development. Meanwhile, parental RNAi indicated that it completely inhibited female fecundity and partially inhibited male fertility once Tchsp90 was knocked down and that it will further shorten the lifespan of T. castaneum. These results suggest that Tchsp90 is essential for development, lifespan, and reproduction in T. castaneum in addition to its response to heat stress.
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