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The Lancang metamorphic complex is a key component of the Three River Tethys Orogen in the SE Tibetan Plateau, with typical rock assemblages and deformation fabrics recording the subduction of the Paleo-Tethys Ocean and subsequent continental collision. In this study, we present new petrographic and structural observations, together with zircon U-Pb and mica 40Ar/39Ar geochronologic data, to reveal the deformation and kinematics of the Lancang metamorphic complex, thus providing insights into the Permian-Triassic evolution of the eastern Paleo-Tethys domain. The subduction of the Paleo-Tethys Ocean and subsequent collision resulted in a range of structural features, including penetrative regional foliations, thrusts, asymmetric folds at various scales, and ductile deformation fabrics such as asymmetric boudins and porphyroclasts. Zircon U-Pb dating of foliated gabbro and 40Ar/39Ar dating of mica schist and mylonite, which preserve shortening fabrics, suggest that the Paleo-Tethys Ocean was subducted during the Late Carboniferous to Permian-Early Triassic, and the collision of the Baoshan and Simao blocks mainly occurred during ca. 237-230 Ma in the SE Tibetan Plateau. Regional deformation likely shifted from shortening to extension ca. 230 Ma, as reflected by post-collision high-K calc-alkaline magmatism. Our results document regional structural patterns and place timing constraints on the evolution of the Paleo-Tethys Ocean. [ABSTRACT FROM AUTHOR]

The Tibetan grassland social-ecological systems are widely held to be highly vulnerable to climate change. We aim to investigate livelihood adaptation strategies of herder households and the types of local institutions that shaped those adaptation strategies. We examined the barriers and opportunities for strengthening adaptive capacity of local herder communities. We designed and implemented a household survey in the herder communities of northern Tibet. The survey results showed that migratory grazing has become less feasible. Storage, diversification, and market exchange have become the dominant adaptation strategies. The adaptation strategies of local herders have been reshaped by local institutional change. Local governmental and market institutions played the dominant roles in reshaping climate adaptation strategies. Although the present livelihood adaption strategies related to sedentary grazing have improved productivity and profitability of the herding livelihood, they have led to continuous deterioration of pastures. The local grazing system has become more and more dependent on artificial feeding and inputs from outside the grazing system. Purchasing forage has become one of the dominant adaptation strategies of local herder households. Multilevel regression modeling of this adaptation behavior showed that explanatory variables related to climate variability, household capital, and local institutional arrangements had statistically significant relationships with the adoption of this adaptation strategy. The results implies that building household capital and promoting the coordination among local governmental, market, and communal institutions are critical for strengthening adaptive capacity of the Tibetan herder communities. [ABSTRACT FROM AUTHOR]

Testis-specific lactate dehydrogenase (LDH-C4) is one of the lactate dehydrogenase (LDH) isozymes that catalyze the terminal reaction of pyruvate to lactate in the glycolytic pathway. LDH-C4 in mammals was previously thought to be expressed only in spermatozoa and testis and not in other tissues. Plateau pika (Ochotona curzoniae) belongs to the genus Ochotona of the Ochotonidea family. It is a hypoxia-tolerant species living in remote mountain areas at altitudes of 3000-5000 m above sea level on the Qinghai-Tibet Plateau. Surprisingly, Ldh-c is expressed not only in its testis and sperm, but also in somatic tissues of plateau pika. To shed light on the function of LDH-C4 in somatic cells, Ldh-a, Ldh-b, and Ldh-c of plateau pika were subcloned into bacterial expression vectors. The pure enzymes of Lactate Dehydrogenase A4 (LDH-A4), Lactate Dehydrogenase B4 (LDH-B4), and LDH-C4 were prepared by a series of expression and purification processes, and the three enzymes were identified by the method of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and native polyacrylamide gel electrophoresis (PAGE). The enzymatic kinetics properties of these enzymes were studied by Lineweaver-Burk double-reciprocal plots. The results showed the Michaelis constant (Km) of LDH-C4 for pyruvate and lactate was 0.052 and 4.934 mmol/L, respectively, with an approximate 90 times higher affinity of LDH-C4 for pyruvate than for lactate. At relatively high concentrations of lactate, the inhibition constant (Ki) of the LDH isoenzymes varied: LDH-A4 (Ki = 26.900 mmol/L), LDH-B4 (Ki = 23.800 mmol/L), and LDH-C4 (Ki = 65.500 mmol/L). These data suggest that inhibition of lactate by LDH-A4 and LDH-B4 were stronger than LDH-C4. In light of the enzymatic kinetics properties, we suggest that the plateau pika can reduce reliance on oxygen supply and enhance its adaptation to the hypoxic environments due to increased anaerobic glycolysis by LDH-C4. [ABSTRACT FROM AUTHOR]

Mutational changes in p53 correlate well with tumorigenesis. Remarkably, however, relatively little is known about the role that p53 variations may play in environmental adaptation. Here we report that codon asparagine-104 (104N) and glutamic acid-104 (104E), respectively, of the p53 gene in the wild zokor (Myospalax baileyi) and root vole (Microtus oeconomus) are adaptively variable, meeting the environmental stresses of the Tibetan plateau. They differ from serine-104 (104S) seen in other rodents, including the lowland subterranean zokor Myospalax cansus, and from serine 106 (106S) in humans. Based on site-directed mutational analysis in human cell lines, the codon 104N variation in M. baileyi is responsible for the adaptive balance of the transactivation of apoptotic genes under hypoxia, cold, and acidic stresses. The 104E p53 variant in Microtus oeconomus suppresses apoptotic gene transactivation and cell apoptosis. Neither 104N nor 104E affects the cell-cycle genes. We propose that these variations in p53 codon 104 are an outcome of environmental adaptation and evolutionary selection that enhance cellular strategies for surviving the environmental stresses of hypoxia and cold (in M. baileyi and M. oeconomus) and hypercapnia (in M. baileyi) in the stressful environments of the Qinghai-Tibet plateau. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau is the youngest and highest plateau on Earth, and its elevation reaches one-third of the height of the troposphere, with profound dynamic and thermal effects on atmospheric circulation and climate. The uplift of the Tibetan Plateau was an important factor of global climate change during the late Cenozoic and strongly influenced the development of the Asian monsoon system. However, there have been heated debates about the history and process of Tibetan Plateau uplift, especially the paleo-altimetry in different geological ages. Here we report a well-preserved skeleton of a 4.6 million-y-old three-toed horse (Hipparion zandaense) from the Zanda Basin, southwestern Tibet. Morphological features indicate that H. zandaense was a cursorial horse that lived in alpine steppe habitats. Because this open landscape would be situated above the timberline on the steep southern margin of the Tibetan Plateau, the elevation of the Zanda Basin at 4.6 Ma was estimated to be ~4,000 m above sea level using an adjustment to the paleo-temperature in the middle Pliocene, as well as comparison with modern vegetation vertical zones. Thus, we conclude that the southwestern Tibetan Plateau achieved the present-day elevation in the mid-Pliocene. [ABSTRACT FROM AUTHOR]

Aim Most species of temperate regions are believed to have shifted to lower latitudes or elevations during the glacial periods of the Quaternary. In this study we test whether this phylogeographic assumption is also true for the plateau zokor ( Eospalax baileyi), a fossorial rodent endemic to the climate-sensitive Qinghai–Tibetan Plateau (QTP), which ranges in elevation from 2600 to 4600 m. Location The QTP of western China. Methods Phylogeographic analyses were conducted based on the mitochondrial cytochrome b gene sequences of 193 individuals from 20 populations over the entire range of the species. Results A total of 54 haplotypes identified in the present study clustered into four geographically correlated clades located in the interior of the QTP (clade A) and at the plateau edge (B, C and D). Molecular calibrations suggest that the interior plateau (A) and plateau-edge (B–D) clades diverged at 1.2 Ma and that the three plateau-edge clades diverged between 0.85 and 0.80 Ma. These estimates are concordant with diastrophism and glaciation events in the QTP. Coalescent tests rejected both the hypothesis that all current populations originated from a single refugium at a low elevation during the Last Glacial Maximum (LGM) and the hypothesis that the two lineages diverged during the LGM. The tests instead supported the hypothesis that there were four refugia during the LGM, and that the four clades diverged prior to the late Pleistocene. Main conclusions Our results suggest that Quaternary diastrophisms and glaciations repeatedly promoted allopatric divergence of the plateau zokor into geographical clades, and that these regional clades subsequently persisted at high elevations, rather than migrating to the low-elevation plateau edge during subsequent glacial ages. [ABSTRACT FROM AUTHOR]