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The responses of soil microbial community and enzyme activities of Phoebe zhennan cultivated under different soil moisture conditions to phosphorus addition
No full textThe importance of conservation and ecological restoration of the rare and economically important tree Phoebe zhennan is increasingly recognized. To this purpose, phosphorus (P) addition has been proposed to improve soil biological attributes and face the anticipated drought under climate change, though few studies have investigated its effect on the interaction between the soil microorganisms and plant host, as well as on ecosystem productivity. We investigated the effect of P addition on soil chemical properties, microbial communities, and enzyme activities in a soil planted with P. zhennan under two levels of water treatments (optimum water and drought treatments). P additions had no significant effect on microbial communities, dissolved organic nitrogen (DON), pH and soil moisture (SM), though the available P (aP) increased. Compared with no P treatment, alkaline phosphate and beta-fructofuranosidase activities increased with P additions in the drought treatment. Drought decreased the total phospholipid-derived fatty acids (PLFAs), arbuscular mycorrhiza fungi (AMF), and fungi PLFAs compared to the well-watered. These findings indicated that P additions does not ameliorate the impact of drought on soil microbial communities and enzyme activities, except alkaline phosphate and beta-fructofuranosidase, and P may not be responsible for regulating biochemical processes essential for maintaining the fertility of soil planted with P. zhennan under drought conditions. It is hypothesized that the lack of effects of P addition on the majority of the microbial properties could be due to the soil mechanism employed by P. zhennan to tolerate harsh conditions
Decreased NAD Activates STAT3 and Integrin Pathways to Drive Epithelial-Mesenchymal Transition
No full textNicotinamide adenine dinucleotide (NAD) plays an essential role in all aspects of human life. NAD levels decrease as humans age, and supplementation with NAD precursors plays a protective role against aging and associated disease. Less is known about the effects of decreased NAD on cellular processes, which is the basis for understanding the relationship between cellular NAD levels and aging-associated disease. In the present study, cellular NAD levels were decreased by overexpression of CD38, a NAD hydrolase, or by treating cells with FK866, an inhibitor of nicotinamide phosphoribosyltransferase (NAMPT). Quantitative proteomics revealed that declining NAD levels downregulated proteins associated with primary metabolism and suppressed cell growth in culture and nude mice. Decreased glutathione synthesis caused a 4-fold increase in cellular reactive oxygen species levels, and more importantly upregulated proteins related to movement and adhesion. In turn, this significantly changed cell morphology and caused cells to undergo epithelial to mesenchymal transition (EMT). Secretomic analysis also showed that decreased NAD triggered interleukin-6 and transforming growth factor beta (TGF) secretion, which activated integrin--catenin, TGF-MAPK, and inflammation signaling pathways to sustain the signaling required for EMT. We further revealed that decreased NAD inactivated sirtuin 1, resulting in increased signal transducer and activator of transcription 3 (STAT3) acetylation and phosphorylation, and STAT3 activation. Repletion of nicotinamide or nicotinic acid inactivated STAT3 and reversed EMT, as did STAT3 inhibition. Taken together, these results indicate that decreased NAD activates multiple signaling pathways to promote EMT and suggests that age-dependent decreases in NAD may contribute to tumor progression. Consequently, repletion of NAD precursors has potential benefits for inhibiting cancer progression
Examining the interglacial high-elevation refugia scenario in East Asian subtropical mountain systems with the frog species Leptobrachium liui
No full textThe effects of Quaternary climatic oscillations on the distributions of organisms in different parts of the world are not equally well understood, limiting the ability to understand the determinants of biodiversity. Compared with the mountain regions in southern Europe and southwestern North America, such effects on high-elevation species in the East Asian subtropical mountain systems located in southern and southeastern China have seldom been addressed. In this study, using Leptobrachium liui (Megophryidae), we made one of the earliest attempts to examine the interglacial high-elevation refugia scenario in these Asian mountains. Based on our current understanding of the study system, we formulated a hypothesis that these frogs of western origin were distributed more widely and continuously during glacial phases, allowing eastward dispersal, and that they are currently isolated in interglacial refugia at higher elevations. Microsatellite data and mitochondrial and nuclear sequence data were obtained with extensive sampling followed by the synthesis of phylogeographic and population genetic analyses and modeling of the species distribution. The analyses revealed a sequential eastward divergence of microsatellite clusters and gene lineages accompanied by a decline in genetic diversity. Molecular dating estimates revealed divergence events in the Pleistocene, and a reduction in local populations was inferred to have occurred at a time comparable to the end of the last glacial. Strong genetic isolation by distance reflecting a more continuous historical distribution was detected. Furthermore, environmental niche models inferred a wide planar distribution during the last glacial maximum, providing further support for the hypothesis
Cys(2)His(2) Zinc Finger Transcription Factor BcabaR1 Positively Regulates Abscisic Acid Production in Botrytis cinerea
No full textAbscisic acid (ABA) is one of the five classical phytohormones involved in increasing the tolerance of plants for various kinds of stresses caused by abiotic or biotic factors, and it also plays important roles in regulating the activation of innate immune cells and glucose homeostasis in mammals. For these reasons, as a "stress hormone," ABA has recently received attention as a candidate drug for agriculture and biomedical applications, prompting significant development of ABA synthesis. Some plant-pathogenic fungi can synthesize natural ABA. The fungus Botrytis cinerea has been used for biotechnological production of ABA. Identification of the transcription factors (TFs) involved in regulation of ABA biosynthesis in B. cinerea would provide new clues to understand how ABA is synthesized and regulated. In this study, we defined a novel Cys(2)His(2) TF, BcabaRl, that regulates the transcriptional levels of ABA synthase genes (bcaba1, bcaba2, bcaba3, and bcaba4) in an ABA-overproducing mutant, B. cinerea TBC-A. Electrophoretic mobility shift assays revealed that recombinant BcabaR1 can bind specifically to both a 14-nucleotide sequence motif and a 39-nucleotide sequence motif in the promoter region of bcaba1 to -4 genes in vitro. A decreased transcriptional level of the bcabaR1 gene in B. cinerea led to significantly decreased ABA production and downregulated transcription of bcaba1 to -4. When bcabaR1 was overexpressed in B. cinerea, ABA production was significantly increased, with upregulated transcription of bcaba1 to -4. Thus, in this study, we found that BcabaR1 acts as a positive regulator of ABA biosynthesis in B. cinerea. IMPORTANCE Abscisic acid (ABA) could make a potentially important contribution to theoretical research and applications in agriculture and medicine. Botrytis cinerea is a plant-pathogenic fungus that was found to produce ABA. There has been a view that ABA is related to the interaction between pathogenic fungi and plants. Identification of regulatory genes involved in ABA biosynthesis may facilitate an understanding of the underlying molecular mechanisms of ABA biosynthesis and the pathogenesis of B. cinerea. Here, we present a positive regulator, BcabaR1, of ABA biosynthesis in B. cinerea that can affect the transcriptional level of the ABA biosynthesis gene cluster, bcaba1 to -4, by directly binding to the conserved sequence elements in the promoter of the bcaba1 to -4 genes. This TF was found to be specifically involved in regulation of ABA biosynthesis. This work provides new clues for finding other ABA biosynthesis genes and improving ABA yield in B. cinerea
Heat stress alters genome-wide profiles of circular RNAs in Arabidopsis
No full text1599 novel circRNAs and 1583 heat stress-specific circRNAs were identified in Arabidopsis. Heat stress enhanced accumulation of circRNAs remarkably. Heat stress altered the sizes of circRNAs, numbers of circularized exons and alterative circularization events. A putative circRNA-mediated ceRNA networks under heat stress was established. Heat stress retards plant growth and destabilizes crop yield. The noncoding RNAs were demonstrated to be involved in plant response to heat stress. As a newly-characterized class of noncoding RNAs, circular RNAs (circRNAs) play important roles in transcriptional and post-transcriptional regulation. A few recent investigations indicated that plant circRNAs were differentially expressed under abiotic stress. However, little is known about how heat stress mediates biogenesis of circRNAs in plants. Here, we uncovered 1599 previously-unknown circRNAs and 1583 heat-specific circRNAs, by RNA-sequencing and bioinformatic analysis. Our results indicated that much more circRNAs were expressed under heat stress than in control condition. Besides, heat stress also increased the length of circRNAs, the quantity of circularized exons, and alternative circularization events. Moreover, we observed a positive correlation between expression patterns of some circRNAs and their parental genes. The prediction of ceRNA (competing endogenous RNA) networks indicated that differentially-expressed circRNAs could influence expression of many important genes, that participate in response to heat stress, hydrogen peroxide, and phytohormone signaling pathways, by interacting with the corresponding microRNAs. Together, our observations indicated that heat stress had great impacts on the biogenesis of circRNAs. Heat-induced circRNAs might participate in plant response to heat stress through the circRNA-mediated ceRNA networks
Phylogenomic analysis demonstrates a pattern of rare and long-lasting concerted evolution in prokaryotes
No full textConcerted evolution, where paralogs in the same species show higher sequence similarity to each other than to orthologs in other species, is widely found in many species. However, cases of concerted evolution that last for hundreds of millions of years are very rare. By genome-wide analysis of a broad selection of prokaryotes, we provide strong evidence of recurrent concerted evolution in 26 genes, most of which have lasted more than similar to 500 million years. We find that most concertedly evolving genes are key members of important pathways, and encode proteins from the same complexes and/or pathways, suggesting coevolution of genes via concerted evolution to maintain gene balance. We also present LRCE-DB, a comprehensive online repository of long-lasting concerted evolution. Collectively, our study reveals that although most duplicated genes may diverge in sequence over a long period, on rare occasions this constraint can be breached, leading to unexpected long-lasting concerted evolution in a recurrent manner
Spatial pattern of population distribution and its correlation with relief amplitude in southwestern China
No full text中国西南地区复杂的地形起伏造就了人口分布的区域差异,研究地形起伏度与区域人口增减以及集疏格局演化的关系,有利于深入理解人口的分布规律和流动趋势,从而为增进对区域人地关系的认识,实现人口、资源、环境可持续利用提供科学依据。以西南地区DEM数据和人口统计数据为基础,采用人口密度、人口集聚度以及人口商度等指标,结合GIS空间分析方法,定量研究了西南地区1995-2010年期间地形起伏度与人口集疏格局演化的关系。结果表明:(1)西南地区县域尺度上的地形起伏度主要以中小起伏为主,其中小起伏(0-200m)占30.34%,中起伏(200-400m)占30.33%,且地形起伏度的空间分布特征与区域地貌类型分布状况基本一致,即小起伏主要出现在四川盆地盆中区域、广西丘陵以及青藏高原高原面,中起伏主要集中分布在云贵高原境内,大起伏和极大起伏主要分布在横断山区、青藏高原东南部边缘以及川西高原地区。(2) 1995-2010年间,西南地区人口西疏东密的集疏格局未发生明显变化,地形起伏度的整体格局根本上决定了区域人口格局的形成。人口流动主要发生在中小起伏地区,且流出人口比例逐渐占据主导地位;而地形起伏度较大的高山以及高原边缘地区多为人口稳定区域。(3)地形起伏度差异决定了西南地区高度集聚和极端稀疏两种人口格局并存的现状。平原、丘陵、低山等起伏较小的地区人口增长迅速;而地形起伏度大的高山以及高原边缘地区人口增减变化不显著
The suitable distribution area of Tsuga longibracteata revealed by a climate and spatial constraint model under future climate change scenarios
No full text长苞铁杉(Tsuga longibracteata)是中国特有的珍贵树种,不仅对研究裸子植物的系统发育、古生态和古气候具有重要作用,而且该树种具有造林、用材和药用等方面的较高价值。研究长苞铁杉在气候变化下的分布格局变化是制定其保护和可持续利用的重要基础。采用最大熵模型(MaxEnt),结合不同时期(当前、2050年和2070年)和不同二氧化碳排放情境下(RCP2.6和RCP8.5)的气候因子变量,探讨气候变化与物种地理分布格局的关系,预测长苞铁杉的潜在分布区变迁。本研究考虑了空间约束对物种分布的限制作用,构建了气候因子预测模型(C)和气候+空间约束因子预测模型(C+S)分别进行潜在分布区预测,比较其结果差异。结果显示,最干月降水量和温度年较差是影响长苞铁杉地理分布的主导气候因子,空间约束因子对长苞铁杉未来的地理分布有重要影响。随时间年限增加,长苞铁杉总潜在适生区面积降低,特别是中高等级的适生区面积有不同程度地减少,分布范围总体向北移动,这些变化趋势在RCP8.5情境下更加突出。这一结果表明未来气候变化会导致长苞铁杉种群分布范围收缩和生境适宜度下降,加剧其受胁程度。加入空间约束因子后,C+S模型的预测精度更高,结果更符合长苞铁杉的迁移、扩散特性。长苞铁杉未来的核心分布区仍位于现存的湘、桂、黔结合部,表明其具有原地避难的特性,应进一步加强对现有野生资源的保护。渝、川、鄂结合部的大巴山等地区是未来气候变化下长苞铁杉的理论分布区域,可作为长苞铁杉应对未来气候变化的引种地区,应提早进行人工引种、栽培等前期研究。研究结果可为气候变化背景下长苞铁杉的保护、物种迁地保存和可持续管理提供科学依据,也可为准确预测濒危、珍稀植物的地理分布范围提供方法参考
Notes on Rubus L.(Rosaceae) from Medog,Tibet,China
No full text该文在野外调查、标本采集、标本查阅与鉴定及文献考证的基础上,对西藏墨脱县产的蔷薇科悬钩子属植物进行了系统整理。结果表明:目前发现该区共有悬钩子属植物28种4变种,其中Rubus lineatus Reinw. var. glabrior Hook. f.为中国分布新记录植物,小柱悬钩子(R. columellaris Tutcher) 、红毛悬钩子(R. wallichianus Wight et Arn.) 、独龙悬钩子(R. taronensis C. Y. Wu ex T. T. Yu et L. T. Lu)和疏松悬钩子(R. efferatus Craib)为西藏分布新记录植物。该文还对《中国植物志》和Flora of China中该属部分学名的不恰当使用进行了探讨
Anti-Osteoporosis Effects Induced by Retinoic Acid in Mice of Hexane Extract from Raw and Processed Polygonum multiflorum
No full text研究生、制首乌正己烷提取物对维甲酸致小鼠骨质疏松的防治作用,并探讨其主要作用机制。采用维甲酸(105 mg·kg~(-1))致小鼠骨质疏松模型,生首乌正己烷提取物高、低剂量组48、24 mg·kg~(-1),清蒸制首乌正己烷提取物高、低剂量组48、24 mg·kg~(-1),黑豆制何首乌正己烷提取物高、低剂量组48、24 mg·kg~(-1),灌胃给药,2周后以比色法测定血清钙、磷含量和碱性磷酸酶(ALP)、抗酒石酸酸性磷酸酶(TRAP)活性,竞争放射免疫法测定血清中骨钙素(BGP)和雌二醇(E2)含量,取股骨进行骨组织形态学观察。结果表明:维甲酸可引起高转换型骨质疏松,与模型组比较,生、制首乌各剂量组可显著升高s-E2的水平(P <0.05),降低s-ALP、s-TRAP和s-BGP的水平(P<0.05,P<0.01);生、制首乌各组与模型组比较,骨组织形态均有不同程度的改善,骨小梁数明显增加。从以上结果可知,生、制首乌正己烷提取物对维甲酸致小鼠骨质疏松有明显的治疗作用,其机制可能与减缓雌激素水平降低,抑制骨高转换有关