甘南亚高山草甸群落的物候谱研究──兼论群落种多样性维持的机制

本文研究了亚高山草甸群落中常见的４２种植物的物候期。研究结果表明,此４２种植物在返青时间顺序、进入生殖生长的个体数量比例和进入生殖生长阶段的起始时间、历期上各不相同。根据返青顺序可将４２种植物分为三类。以单子叶禾莎草的返青时间为最早,多年生双子叶植物的返育时间较晚。根据进入生殖生长的个体占种群总个体数量的比例可分为：（１）生殖生长的个体比例在２０％以下,主要靠营养繁殖的种类;（２）具有双重繁殖特性的种类;（３）生殖个体占５０％以上的种类和（４）完全依靠有性繁殖的种类共四类。根据进入生殖生长的起始时间可分为三类。以上结果在一定程度上说明了植物种间由于在生长发育时间上的错位,减缓了种间对资源（如土壤矿物质营养）的竞争,使得群落中有多个种共存。     

珠穆朗玛峰自然保护区小叶金露梅灌丛群落数量分类和排序及其多样性垂直格局

根据野外样方调查数据,采用双向种指示分析(TWINSPAN)和典范对应分析(CCA),对珠穆朗玛峰国家级自然保护区小叶金露梅灌丛群落进行分类和排序,并分析物种多样性沿海拔梯度的分布格局。结果表明:(1)该区域24个样地中,记载的维管束植物共有23科45属80种,出现频度较高的种有小叶金露梅(Potentilla parvifolia)、高山嵩草(Kobresia pygmaea)、木根香青(Anaphalis xylorhiza)、垫状点地梅(Androsace tapete)、藏沙蒿(Artemisia wellbyi)、垫状雪灵芝(Arenaria pulvinata)和柴胡红景天(Rhodiola bupleuroides)等。(2)经TWINSPAN等级分类将该区域小叶金露梅灌丛24个样地划分为10个群丛类型。(3)样地和物种CCA二维排序结果表明,海拔和坡位是影响该区域小叶金露梅灌丛群落和物种分布格局的主要环境因子。(4)该区域小叶金露梅灌丛群落物种丰富度、Shannon-Wiener指数和Simpson指数均随海拔升高呈下降的趋势,而Pielou指数呈上升的趋势。(5)样地中优势种小叶金露梅的盖度和高度沿海拔梯度呈显著下降趋势。     

Electrophoresis of periodontal pathogens in poly(ethyleneoxide) solutions with uncoated capillary

Periodontitis is a prevalent inflammatory disease caused by different species of anaerobic bacteria such as Porphyromonas gingivalis (P.g), Treponema denticola (T.d), and Tannerella forsythia (T.f). We compared the separation result of DNA ladders in hydroxyethyl cellulose, poly(ethyleneoxide) (PEO), and polyethylene glycol and analyzed the effect of polymer concentration, electric field, and temperature of the background electrolyte on the separation performance. Results demonstrated that there was a linear relationship (R = 0.942) for 100 to 700 bp of DNA and its migration time. Finally, the polymerase chain reaction products of P.g, T.d, and T.f were successfully identified within 8.5 min in 0.5% PEO with uncoated capillary.     

Tumor-Like Stem Cells Derived from Human Keloid Are Governed by the Inflammatory Niche Driven by IL-17/IL-6 Axis

Background

Alterations in the stem cell niche are likely to contribute to tumorigenesis; however, the concept of niche promoted benign tumor growth remains to be explored. Here we use keloid, an exuberant fibroproliferative dermal growth unique to human skin, as a model to characterize benign tumor-like stem cells and delineate the role of their “pathological” niche in the development of the benign tumor.

Methods and Findings

Subclonal assay, flow cytometric and multipotent differentiation analyses demonstrate that keloid contains a new population of stem cells, named keloid derived precursor cells (KPCs), which exhibit clonogenicity, self-renewal, distinct embryonic and mesenchymal stem cell surface markers, and multipotent differentiation. KPCs display elevated telomerase activity and an inherently upregulated proliferation capability as compared to their peripheral normal skin counterparts. A robust elevation of IL-6 and IL-17 expression in keloid is confirmed by cytokine array, western blot and ELISA analyses. The altered biological functions are tightly regulated by the inflammatory niche mediated by an autocrine/paracrine cytokine IL-17/IL-6 axis. Utilizing KPCs transplanted subcutaneously in immunocompromised mice we generate for the first time a human keloid-like tumor model that is driven by the in vivo inflammatory niche and allows testing of the anti-tumor therapeutic effect of antibodies targeting distinct niche components, specifically IL-6 and IL-17.

Conclusions/Significance

These findings support our hypothesis that the altered niche in keloids, predominantly inflammatory, contributes to the acquirement of a benign tumor-like stem cell phenotype of KPCs characterized by the uncontrolled self-renewal and increased proliferation, supporting the rationale for in vivo modification of the “pathological” stem cell niche as a novel therapy for keloid and other mesenchymal benign tumors.     

Twelve novel polymorphic microsatellite loci for the Yellow grouper (Epinephelus awoara) and cross-species amplifications

Yellow grouper (Epinephelus awoara) is a commercially important marine fish species. A dinucleotide-enriched genomic library of E. awoara was constructed using the method of FIASCO. Twelve loci were polymorphic in a test population with alleles per locus ranging from two to eight, and observed and expected heterozygosities per locus from 0.13 to 1.00 and from 0.20 to 0.86, respectively. Five loci significantly deviated from Hardy–Weinberg equilibrium and no significant linkage disequilibrium was found between pairs of loci. Cross-species amplification of these polymorphic microsatellite loci was performed in additional two related species. These polymorphic microsatellite loci would be useful for investigating genetic diversity of E. awoara and related species. L. Zhao and C. Shao have contributed equally to this work.     

气候变暖抑制西藏拉萨河大果圆柏树木生长

西藏拉萨河作为雅鲁藏布江最大的支流,近几十年气温已显著上升,将可能从不同的程度上影响流域内植被的生长动态。以拉萨河流域主要分布的树种—大果圆柏(Sabina tibetica)为研究对象,采用树木年轮学的方法对大果圆柏进行了年轮采样和处理,建立了树木年表,探讨了大果圆柏过去的生长动态特征,并用相关分析、偏相关分析和滑动相关分析的方法分析了不同气候因子与树木年轮宽度指数的关系。研究结果表明,大果圆柏树木年轮宽度指数与前一年6—10月和当年3—7月的降水、相对湿度和帕默尔干旱指数(PDSI)呈显著的正相关关系,而与前一年6—9月和当年3—8月的平均温度和平均最高温度以及当年5—7月的平均最低温度均呈显著的负相关关系,表明了气候变暖引起的干旱胁迫是导致近几十年来大果圆柏树木径向生长下降的主要原因。在未来气候变暖背景下,拉萨河大果圆柏林将可能出现生长下降,甚至死亡的现象,将潜在驱动区域森林减少。     

A New World Monkey Resembles Human in Bitter Taste Receptor Evolution and Function via a Single Parallel Amino Acid Substitution

Bitter taste receptors serve as a vital component in the defense system against toxin intake by animals, and the family of genes encoding these receptors has been demonstrated, usually by family size variance, to correlate with dietary preference. However, few systematic studies of specific Tas2R to unveil their functional evolution have been conducted. Here, we surveyed Tas2R16 across all major clades of primates and reported a rare case of a convergent change to increase sensitivity to β-glucopyranosides in human and a New World monkey, the white-faced saki. Combining analyses at multiple levels, we demonstrate that a parallel amino acid substitution (K172N) shared by these two species is responsible for this functional convergence of Tas2R16. Considering the specialized feeding preference of the white-faced saki, the K172N change likely played an important adaptive role in its early evolution to avoid potentially toxic cyanogenic glycosides, as suggested for the human TAS2R16 gene.     

藏东木本植物群落功能性状分布与环境的关系

研究植物群落功能性状间的相关关系及其对环境变化的响应,能够有效揭示植物功能性状的权衡模式及其对环境的适应策略。藏东昌都地区位于横断山脉西北部,复杂气候地貌孕育了丰富的植物资源,是青藏高原森林灌丛生态系统主要组分和国际生物多样性保护的热点地区。以藏东森林灌丛群落优势木本植物为研究对象,在大量野外调查基础上,采用相关分析、主成分分析、线性回归和方差分析等方法,研究了该区域植物功能性状间的相关关系、功能性状对环境变量的响应规律以及功能性状的变异来源。结果表明：(1)藏东木本植物表现出适应高寒环境的性状权衡模式,即：比叶面积、叶体积较小而叶干物质含量较大,叶磷含量和叶钾含量协同变化;(2)海拔和气候变量共同驱动着藏东木本植物功能性状的变化,并且藏东木本植物倾向于采取“高投入—慢回报”提高御寒能力的保守型适应策略;(3)海拔是影响藏东植物功能性状变异最显著的环境变量,种间变异在藏东植物群落功能性状随环境变化中起主要作用。研究结果揭示了藏东木本植物功能性状的权衡模式及其对高寒环境的适应策略,有助于加深对藏东自然植物资源分布规律和生态功能的认识,为区域生态系统功能和生物多样性保护提供科学依据。     

Microarchitecture and Nanomechanical Properties of Trabecular Bone After Strontium Administration in Osteoporotic Goats

Strontium (Sr) ralenate is a new agent used for the prevention and treatment of osteoporosis. As a bone-seeking element, 98% of Sr is deposited in the bone and teeth after oral ingestion. However, the effect of Sr treatment on bone microarchitecture and bone nanomechanical properties remains unclear. In this study, 18 osteoporotic goats were divided into four groups according to the treatment regimen: control, calcium alone (Ca), calcium and Sr at 24 mg/kg (Ca + 24Sr), and calcium and Sr at 40 mg/kg (Ca + 40Sr). The effects of Sr administration on bone microarchitecture and nanomechanical properties of trabecular bones were analyzed with micro-CT and nanoindentation test, respectively. Serum Sr levels increased six- and tenfold in the Ca + 24Sr and Ca + 40Sr groups, respectively. Similarly, Sr in the bone increased four- and sixfold in these two groups. Sr administration significantly increased trabecular bone volume fraction, trabecular thickness, and double-labeled new bone area. Sr administration, however, did not significantly change the nanomechanical properties of trabecular bone (elastic modulus and hardness). The data suggested that Sr administration increased trabecular bone volume and improved the microarchitecture while maintaining the intrinsic tissue properties in the osteoporotic goat model.