青藏高原和内蒙古高原典型草地植物叶片肾型和哑铃型气孔器气孔特征及其与环境的关系

该研究利用植物制片技术,以中国青藏高原和内蒙古高原典型草地常见种或优势种植物的叶片为研究对象,通过比较分析叶片哑铃型气孔器和肾型气孔器的特征及其与环境因子的关系,揭示植物叶片两类气孔器对环境因子的响应策略。结果表明:(1)叶片哑铃型气孔器气孔指标的变异系数小于肾型气孔器。(2)叶片哑铃型气孔器气孔指标与环境气候指标的关系弱于肾型气孔器。(3)叶片哑铃型气孔器气孔特征与环境关系在叶片上下表面之间存在显著差异,而肾型气孔器气孔特征与环境因子的关系在叶片上下表面之间无显著差异。(4)叶片哑铃型气孔器的气孔特征与降水关系密切,而肾型气孔器气孔特征与温度关系密切。(5)同一种气孔器的气孔特征在两个地区(青藏高原和内蒙古高原)间存在显著差异。研究认为,肾型气孔器和哑铃型气孔器的气孔特征及其与环境之间的关系存在差异,在分析气孔特征时有必要将肾形与哑铃形保卫细胞形成的气孔器加以区分,该研究结果有助于进一步理解中国草地植物叶气孔特征对气候变化的响应与适应策略。     

Hepatoprotective effect of Herpetospermum caudigerum Wall. on carbon tetrachloride‐induced hepatic fibrosis in rats

Tibetan medicine Herpetospermum caudigerum Wall. (HCW) has long been employed to treat hepatitis, inflammatory diseases and jaundice according to the records of “The Four Medical Tantras” in China. This study was investigated to explore the protective effects of HCW on hepatic fibrosis and the possible mechanism in a rat model. Hepatic fibrosis was established by intragastric administration of 3 ml/kg carbon tetrachloride (CCl₄) twice a week for 6 weeks. CCl₄‐treated rats were received HCW (1 and 3 g/kg/d) and silymarin (0.1 g/kg/d) from 3 to 6 weeks. The results showed that HCW could significantly decrease the levels of AST, ALT, HA, LN, PCIII, Col IV, TNF‐α, IL‐1β and IL‐6. Moreover, HCW could effectively inhibit collagen deposition and reduce the pathological damage. Analysis experiments finally exhibited that HCW was able to markedly inhibit hepatic fibrosis by modulating the expressions of NF‐κB p65, IκBα, Samd3 and TGF‐β1 proteins. Therefore, our results suggest that HCW has hepatoprotective activity against CCl₄‐induced hepatic fibrosis in rats by regulating the inflammatory responses.     

Shifts in priming partly explain impacts of long‐term nitrogen input in different chemical forms on soil organic carbon storage

Input of labile organic carbon can enhance decomposition of extant soil organic carbon (SOC) through priming. We hypothesized that long‐term nitrogen (N) input in different chemical forms alters SOC pools by altering priming effects associated with N‐mediated changes in plants and soil microbes. The hypothesis was tested by integrating field experimental data of plants, soil microbes and two incubation experiments with soils that had experienced 10 years of N enrichment with three chemical forms (ammonium, nitrate and both ammonium and nitrate) in an alpine meadow on the Tibetan Plateau. Incubations with glucose–¹³C addition at three rates were used to quantify effects of exogenous organic carbon input on the priming of SOC. Incubations with microbial inocula extracted from soils that had experienced different long‐term N treatments were conducted to detect effects of N‐mediated changes in soil microbes on priming effects. We found strong evidence and a mechanistic explanation for alteration of SOC pools following 10 years of N enrichment with different chemical forms. We detected significant negative priming effects both in soils collected from ammonium‐addition plots and in sterilized soils inoculated with soil microbes extracted from ammonium‐addition plots. In contrast, significant positive priming effects were found both in soils collected from nitrate‐addition plots and in sterilized soils inoculated with soil microbes extracted from nitrate‐addition plots. Meanwhile, the abundance and richness of graminoids were higher and the abundance of soil microbes was lower in ammonium‐addition than in nitrate‐addition plots. Our findings provide evidence that shifts toward higher graminoid abundance and changes in soil microbial abundance mediated by N chemical forms are key drivers for priming effects and SOC pool changes, thereby linking human interference with the N cycle to climate change.     

Fossil leaves of Buxus (Buxaceae) from the Upper Pliocene of Yunnan,SW China

A new species, Buxus pliosinica H.S. Huang, T. Su et Z.K. Zhou n. sp. (Buxaceae) is designated based on leaf architecture and cuticular features of five compressed fossil leaves from the Upper Pliocene Sanying Formation of Yunnan, SW China. Leaves of B. pliosinica are elliptic and small, with entire margin, retuse tip, intramarginal vein, and exmedially ramified tertiary veins. The leaves are hypostomatic with anomocytic stomatal apparatuses and giant stomata. Based on comparisons of leaf morphological and cuticular features, B. sempervirens Linnaeus is considered as the nearest living relative of B. pliosinica. Morphologically, these species share similar elliptic shape and size, cuneate base, retuse tip, similar ranges of petiole length, angles of 2° vein to midvein, and distance from the intramarginal vein to the margin. In terms of cuticular features, they are similar in type of stomatal apparatus, maximum length of giant stomata and range of stomatal length, but differ in the presence of indumentum. This discovery represents the first fossil record of Buxus from the SE margin of the Tibetan Plateau, and confirms the existence of Buxus in this region by the late Pliocene. Meanwhile, the newly described fossil species contributes to our understanding of the evolution of extant Buxus.     

川西高原不同坡向云、冷杉树轮对快速升温的响应差异

在川西高原松潘县二道海林区的东南坡、西北坡和扎日寺林区的东坡用零信号法建立4条云、冷杉树轮年表,通过年轮 气候响应分析、多因素方差分析等方法研究不同坡向树木生长对快速升温的响应差异.结果表明： 快速升温(1980年)后,东坡紫果云杉生长显著加速(0.011 a^-1),而西北坡紫果云杉生长则显著降低(-0.006 a^-1),东南坡紫果云杉和西北坡岷江冷杉生长降低,但不显著.随着快速升温,不同坡向云、冷杉径向生长与气候因子的关系均出现显著变化.快速升温后,生长季温度对东坡紫果云杉径向生长的促进作用显著增加,对东南坡和西北坡紫果云杉径向生长的抑制作用也显著增加,但生长季温度对西北坡岷江冷杉径向生长的影响在升温前后变化不明显.5月降水量对东坡紫果云杉径向生长由升温前的抑制作用变为升温后的显著促进作用,而对东南坡和西北坡紫果云杉径向生长的抑制作用显著增加,5月降水量对西北坡岷江冷杉径向生长的影响在升温前后变化不明显.树轮与帕尔默干旱指数响应分析表明,快速升温后,不同坡向的土壤湿度变化是造成树轮响应差异的重要原因.多因素方差分析表明,坡向与温度、降水的综合作用是影响紫果云杉径向生长的重要因素.因此,在模拟预测树木生长对气候变暖的响应动态时,应考虑不同坡向与温度、降水的综合作用.     

Mito‐nuclear phylogeography of the cyprinid fish Gymnodiptychus dybowskii in the arid Tien Shan region of Central Asia

We evaluated the phylogeography and historical demography of the cyprinid fish Gymnodiptychus dybowskii (subfamily Schizothoracinae) across three northern Qinghai‐Tibetan Plateau (QTP) river systems in the Tien Shan range: the Kaidu River, Ili River and Junggar Basin. Results from both mtDNA (16S rRNA and Cyt b) and nuDNA (RAG‐2) resolved three reciprocally monophyletic clades, one in each of the three river basins. Estimated divergence times (highest posterior density (HPD) 2.4–3.7 Mya) are consistent with the hypothesis that these three clades are products of vicariance resulting from the intensive uplift of QTP and Tien Shan, and resulting expansion of the Taklimakan and Gurbantunggut deserts. Several lines of evidence indicate dynamic demographic histories for the three clades, with late Quaternary population bottlenecks and expansions in the Kaidu and Ili rivers and, possibly, a Holocene decline in the Junggar Basin. For conservation purposes, the three clades should be treated as species or minimally, as evolutionarily significant units (ESUs). They have experienced decades of anthropogenic disturbance and preservation of the three species/ESUs will require more sustainable management of the aquatic resources.     

交通设施对可可西里藏羚季节性迁移的影响

本文基于对可可西里自然保护区内藏羚跨越青藏公路及青藏铁路的监测结果,初步探讨了公路及铁路对藏羚季节性迁移的影响。观测结果显示,目前对藏羚迁移的主要干扰因素为：交通设施自身的屏障作用、人为活动、公路交通流量、未清理施工现场及未恢复植被等。本文通过对野生动物通道的使用情况监测和对不同通道形式的使用评价,为未来铁路建设和野生动物通道的优化提供了科学依据。     

Divergent adaptation to Qinghai-Tibetan Plateau implicated from transciptome study of Gymnocypris dobula and Schizothorax nukiangensis

The Schizothoracine fishes are widely distributed in the Qinghai-Tibetan Plateau (QTP) area and its peripheral regions, which provide a prime example of adaptation in highland aquatic environments. Recent progresses have revealed various genetic adaptations of these fishes by comparing to distantly related lowerland species, however, comparative studies on closely-related species of different altitudes are still lacking. In this study, we sequenced and annotated a primitive Schizothoracine fish Schizothorax nukiangensis Tsao and a highly specialized one Gymnocypris dobula. We performed evolutionary analyses to investigate the candidate genes and signaling pathways involved QTP highland adaptation in both Schizothoracine fishes. Analysis of the 11,007 one-copy orthologs to the primitive cyprinid species, Danio rerio, revealed that both G. dobula and S. nukiangensis showed elevated evolutionary rates. A large number of genes related to hypoxia, including genes involved metabolic processes and cardiovascular system development, exhibited signatures of positive selection in both Schizothoracine fishes, but very few positively selected genes were found overlapping among these Schizothoracines. Our results indicated divergent genetic adaptation to highland environment for aquatic species living in QTP.     

西藏地区雪层杜鹃遗传多样性的AFLP分析

采用AFLP技术对西藏地区雪层杜鹃（Rhododendron nivale）5个天然种群135份材料进行遗传多样性和遗传分化研究。筛选得出的6对引物共扩增产物273条DNA片段,扩增多态位点百分率为85.71%。5个雪层杜鹃种群的遗传多样性指标表现了相似的变化趋势,Nei基因多样性指数（h）和Shannon信息指数（I）的变化趋势一致,均为工布江达县种群 < 米林种群 < 嘎隆拉种群 < 色季拉山种群 < 红拉山种群。POPGENE分析结果表明雪层杜鹃在物种水平（PPL=85.71%,I=0.415 1,h=0.273）具有较高的遗传多样性,种群水平（PPL=62.26%,I=0.280 3,h=0.184 1）的遗传多样性较低。AMOVA分析结果表明36%的遗传变异存在于种群间,64%的遗传变异存在于种群内,雪层杜鹃种群间的遗传分化系数（G_st=0.324）与AMOVA分析得到的遗传变异分布结果一致。UPGMA聚类结果说明雪层杜鹃的遗传距离与地理距离和海拔高度没有明显的相关性。综合分析,引起雪层杜鹃的遗传变异的原因可能是地理环境不同和种群的生境类型差异。最后就雪层杜鹃的合理开发和保护提出建议。