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The tick Dermacentor everestianus mainly distributed in Tibet, China and Nepal, and can transmit some pathogens causing great damages in Qinghai-Tibet Plateau. This study investigated the life cycle and development characteristics of D. everestianus under field conditions. The average duration of the whole life cycle of D. everestianus was 124.4 days, with the host available in the field plot. Under natural conditions, the mean feeding, preoviposition and oviposition period of female ticks were 6.1, 17.9 and 21.2 days, respectively. The incubation time of eggs was the longest phase in the life cycle of the ticks (26 days on average). Moreover, the weight of engorged females was highly positively correlated with the number of the eggs that were laid (r = 0.81, P < 0.05). The reproductive efficiency index and reproductive fitness index in females were 7.3 and 5.9, respectively. The above findings suggest that the tick D. everestianus have evolved well adaptability to the highland areas. [ABSTRACT FROM AUTHOR]

Phytases play a very important role in increasing phytate digestion and reducing phosphorus pollution in the environment, and phytate-degrading bacteria have a ubiquitous distribution in the environment. Due to its extremely harsh environment, the Tibetan Plateau breeds possibly abundant, extreme microorganisms. In this research, 67 phytate-degrading bacteria were isolated from different habitats in the Tibetan Plateau. Among all isolates, 40.3% were screened from farmland, 25.3% from wetland, 4.5% from saline-alkaline soil, 7.5% from hot springs, and 22.4% from lawns, which showed that the distribution of the phytate-degrading bacteria varied with habitats. By the PCR-RFLP method, 16 different species were identified and named, 4 of which are reported for the first time as phytate-degrading bacteria, that is, Uncultured Enterococcus sp. GYPB01, Bacillaceae bacterium strain GYPB05, Endophytic bacterium strain GYPB16, and Shigella dysenteria strain GYPB22. Through the assay of phytase activity of 16 strains, Klebsiella sp. strain GYPB15 displayed the highest capability of phytase production. Through analysis of the optimum pH, the optimum temperature, and the thermal stability of enzyme from 16 strains, some especial phytate-degrading bacteria were obtained. Our findings clearly indicate a good relation between the composition of the soils from the different environments in the Tibetan Plateau and populations of cultivable phytate-degrading bacteria. Moreover, extreme harsh soils are logically the best soils in which to find some strains of phytate-degrading bacteria for exploiting in the fields of biotechnology and industry. [ABSTRACT FROM AUTHOR]

The Qinghai-Tibetan Plateau (QTP) has become one of the hotspots for phylogeographical studies due to its high species diversity. However, most previous studies have focused on the effects of the Quaternary glaciations on phylogeographical structures and the locations of glacial refugia, and little is known about the effects of the aridization of interior Asia on plant population structure and speciation. Here the chloroplast DNA (cpDNA) trnT-trnF and trnS-trnfM sequences were used to investigate the differentiation and phylogeographical history of 14 Ephedra species from the QTP and northern China, based on a sampling of 107 populations. The phylogeographical analysis, together with phylogenetic reconstruction based on combined four cpDNA fragments (rbcL, rpl16, rps4, and trnS-trnfM), supports three main lineages (eastern QTP, southern QTP, and northern China) of these Ephedra species. Divergence of each lineage could be dated to the Middle or Late Miocene, and was very likely linked to the uplift of the QTP and the Asian aridification, given the high drought and/or cold tolerance of Ephedra. Most of the Ephedra species had low intraspecific variation and lacked a strong phylogeographical structure, which could be partially attributed to clonal reproduction and a relatively recent origin. In addition, ten of the detected 25 cpDNA haplotypes are shared among species, suggesting that a wide sampling of species is helpful to investigate the origin of observed haplotypes and make reliable phylogeographical inference. Moreover, the systematic positions of some Ephedra species are discussed. [ABSTRACT FROM AUTHOR]

Abstract: The Himalaya–Hengduan Mountains region (HHM) in the southern and southeastern Qinghai-Tibetan Plateau (QTP) is considered an important reservoir and a differentiation center for temperate and alpine plants in the Cenozoic. To reveal how plants responded to the Quaternary climatic oscillations in the QTP, the phylogeographical histories of a few subalpine and alpine plants have been investigated, but nearly all studies used only uniparentally inherited cytoplasmic DNA markers, and only a couple of them included sampling from the Himalaya. In this study, range-wide genetic variation of the Himalayan hemlock (Tsuga dumosa), an important forest species in the HHM, was surveyed using DNA markers from three genomes. All markers revealed genetic depauperation in the Himalaya and richness in the Hengduan Mountains populations. Surprisingly, population differentiation of this wind-pollinated conifer is very high in all three genomes, with few common and many private nuclear gene alleles. These results, together with fossil evidence, clearly indicate that T. dumosa recolonized the Himalaya from the Hengduan Mountains before the Last Glacial Maximum (LGM), accompanied with strong founder effects, and the influence of the earlier glaciations on demographic histories of the QTP plants could be much stronger than that of the LGM. The strong population differentiation in T. dumosa could be attributed to restricted gene flow caused by the complicated topography in the HHM that formed during the uplift of the QTP, and thus sheds lights on the importance of geographical isolation in the development of high plant species diversity in this biodiversity hotspot. [Copyright &y& Elsevier]

Fossil shells of the gastropod Gyraulus sp. are widespread in the sediments of wetlands and lakes, and in fluvial and lacustrine depositional sequences on the Tibetan Plateau (TP). Although aragonite shells of Gyraulus sp. are a potentially valuable archive of information on environmental changes, the living environment of Gyraulus sp. and the significance of its shell geochemistry (e.g., Sr/Ca s , Mg/Ca s , δ13C s, δ18O s) are unknown or disputed. In this study we investigated living specimens of the dominant species of Gyraulus sp. (Gyraulus convexiusculus) in rivers, wetlands, and lakes on the TP, together with its fossil shells in the Holocene lacustrine sediments of Nam Co (NC) on the TP. Specifically, we measured the values of Sr/Ca s , Mg/Ca s , δ13C s, and δ18O s of the modern and fossil shells. Our results indicate that the hydrochemical composition and electrical conductivity of the ambient water significantly affect the survival and abundance of G. convexiusculus. The environmental tolerance of G. convexiusculus can be ordered as: carbonate-type > sulfate-type > chloride-type. Additionally, we speculate that the upper threshold of electrical conductivity for the survival of G. convexiusculus does not exceed ∼4544 μS/cm. Furthermore, we established the relationship between modern G. convexiusculus shells and its host water and developed Gyraulus -based transfer functions (TFs). To assess their potential for paleoenvironment reconstruction, the TFs were then applied to fossil shells of G. convexiusculus collected from a Holocene lake sediment profile from a terrace around NC. We show that Sr/Ca s in G. convexiusculus is a potentially reliable proxy for reconstructing the Sr/Ca of the paleo-water (Sr/Ca Paleo-w) and the paleoconductivity. By contrast, Mg/Ca s in G. convexiusculus cannot be used for environmental reconstruction. δ13C s in G. convexiusculus primarily reflects the δ13C DIC of the host water. When the host water is deficient in HCO 3 − + CO 3 2− (<280 mg/L) there is an increased supply of dissolved carbon derived from organic sources to the shells of G. convexiusculus. Overall, δ18O s in G. convexiusculus is likely one of the most reliable indicators for the δ18O w of the host water of the lakes on the TP. • Hydrochemical composition of ambient water influences distribution of Gyraulus sp. • Sr/Ca s of G. convexiusculus is a valuable proxy for paleoenvironmental studies. • Mg/Ca s of G. convexiusculus cannot be used for paleoenvironmental studies. • δ13C s of G. convexiusculus depends on the δ13C DIC of the host water. • G. convexiusculus is one of the most reliable archive of δ18O w. [ABSTRACT FROM AUTHOR]