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Search Results: 1 - 10 of 104200 matches for " Ximei Zhang "
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Nitrogen deposition alters soil chemical properties and bacterial communities in the Inner Mongolia grassland

Ximei Zhang,Xingguo Han,

环境科学学报(英文版) , 2012,
Abstract: Nitrogen deposition has dramatically altered biodiversity and ecosystem functioning on the earth; however, its effects on soil bacterial community and the underlying mechanisms of these effects have not been thoroughly examined. Changes in ecosystems caused by nitrogen deposition have traditionally been attributed to increased nitrogen content. In fact, nitrogen deposition not only leads to increased soil total N content, but also changes in the NH4+-N content, NO3--N content and pH, as well as changes in the heterogeneity of the four indexes. The soil indexes for these four factors, their heterogeneity and even the plant community might be routes through which nitrogen deposition alters the bacterial community. Here, we describe a 6-year nitrogen addition experiment conducted in a typical steppe ecosystem to investigate the ecological mechanism by which nitrogen deposition alters bacterial abundance, diversity and composition. We found that various characteristics of the bacterial community were explained by different environmental factors. Nitrogen deposition decreased bacterial abundance that is positively related to soil pH value. In addition, nitrogen addition decreased bacterial diversity, which is negatively related to soil total N content and positively related to soil NO3--N heterogeneity. Finally, nitrogen addition altered bacterial composition that is significantly related to soil NH4+-N content. Although nitrogen deposition significantly altered plant biomass, diversity and composition, these characteristics of plant community did not have a significant impact on processes of nitrogen deposition that led to alterations in bacterial abundance, diversity and composition. Therefore, more sensitive molecular technologies should be adopted to detect the subtle shifts of microbial community structure induced by the changes of plant community upon nitrogen deposition.

Zhang Ximei,

生态学报 , 1989,
Abstract: 本文系用盆裁法,对在干旱半干旱地区种植的八种主要作物——玉米、高粱、谷子、糜子、春麦、扁豆、胡麻、苜蓿等在适宜水分,轻度干旱、中度干旱、严重干旱、极严重干旱等五种土壤水分条件下的耗水特性进行了系统研究,比较了它们在耗水特性上的差异,并寻找了这种差异与需水日变化的关系,为其在干旱半干旱地区的合理布局与结构及其提高水分利用效率、旱作栽培提供了科学依据。
Soil Bacterial Communities Respond to Mowing and Nutrient Addition in a Steppe Ecosystem
Ximei Zhang, Quansheng Chen, Xingguo Han
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0084210
Abstract: In many grassland ecosystems, nitrogen (N) and phosphorus (P) are added to improve plant productivity, and the aboveground plant biomass is mowed and stored as hay for the bullamacow. Nutrient addition and mowing affect the biodiversity and ecosystem functioning, and most of the previous studies have primarily focused on their effects on macro-organisms, neglecting the responses of soil microbial communities. In this study, we examined the changes in three community attributes (abundance, richness, and composition) of the entire bacterial kingdom and 16 dominant bacterial phyla/classes in response to mowing, N addition, P addition, and their combinations, by conducting a 5-year experiment in a steppe ecosystem in Inner Mongolia, China. Overall, N addition had a greater effect than mowing and P addition on most of these bacterial groups, as indicated by changes in the abundance, richness and composition in response to these treatments. N addition affected these soil bacterial groups primarily through reducing soil pH and increasing available N content. Meanwhile, the 16 bacterial phyla/classes responded differentially to these experimental treatments, with Acidobacteria, Acidimicrobidae, Deltaproteobacteria, and Gammaproteobacteria being the most sensitive. The changes in the abundance, richness, and composition of various bacterial groups could imply some potential shift in their ecosystem functions. Furthermore, the important role of decreased soil pH caused by N addition in affecting soil bacterial communities suggests the importance of restoring acidified soil to maintain soil bacterial diversity.
Soil Bacterial Communities Respond to Climate Changes in a Temperate Steppe
Ximei Zhang, Guangming Zhang, Quansheng Chen, Xingguo Han
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0078616
Abstract: Climate warming and shifting precipitation regimes are affecting biodiversity and ecosystem functioning. Most studies have focused on the influence of warming and altered precipitation on macro-organisms, whereas the responses of soil microbial communities have been neglected. We studied the changes in the abundance, richness, and composition of the entire bacterial kingdom and 16 dominant bacterial phyla/classes in response to increased precipitation, warming, and their combination, by conducting a 5-year experiment in a steppe ecosystem in Inner Mongolia, China. Watering had a greater effect than warming on almost all the bacterial groups as indicated by changes in all the three attributes (abundance, richness, and composition). The 16 phyla/classes responded differentially to the experimental treatments, with Acidobacteria and Gamma-proteobacteria being the most sensitive. Stepwise regression analyses further revealed that climate changes altered the abundance and richness of bacterial groups primarily through direct routes (e.g., increasing soil water content), and changed the community composition through both direct and indirect routes (e.g., reducing soil total nitrogen content and increasing soil pH). The diverse responses of various bacterial groups could imply some potential shift in their ecosystem functions under climate changes; meanwhile, the indirect routes that are important in altering bacterial composition suggest that specific strategies (e.g., adding NH4NO3 to maintain soil nitrogen content and pH) could be adopted to maintain soil microbial composition under climate changes.
Genetic Mapping and Characteristics of Genes Specifically or Preferentially Expressed during Fiber Development in Cotton
Ximei Li, Daojun Yuan, Jinfa Zhang, Zhongxu Lin, Xianlong Zhang
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0054444
Abstract: Cotton fiber is an ideal model to study cell elongation and cell wall construction in plants. During fiber development, some genes and proteins have been reported to be specifically or preferentially expressed. Mapping of them will reveal the genomic distribution of these genes, and will facilitate selection in cotton breeding. Based on previous reports, we designed 331 gene primers and 164 protein primers, and used single-strand conformation polymorphism (SSCP) to map and integrate them into our interspecific BC1 linkage map. This resulted in the mapping of 57 loci representing 51 genes or proteins on 22 chromosomes. For those three markers which were tightly linked with quantitative trait loci (QTLs), the QTL functions obtained in this study and gene functions reported in previous reports were consistent. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of 52 polymorphic functional primers showed that 21 gene primers and 17 protein primers had differential expression between Emian22 (Gossypium hirsutum) and 3–79 (G. barbadense). Both RT-PCR and quantitative real-time PCR (qRT-PCR) analyses of the three markers tightly linked with QTLs were consistent with QTL analysis and field experiments. Gene Ontology (GO) categorization revealed that almost all 51 mapped genes belonged to multiple categories that contribute to fiber development, indicating that fiber development is a complex process regulated by various genes. These 51 genes were all specifically or preferentially expressed during fiber cell elongation and secondary wall biosynthesis. Therefore, these functional gene-related markers would be beneficial for the genetic improvement of cotton fiber length and strength.
Association of ADAM33 gene polymorphisms with adult allergic asthma and rhinitis in a Chinese Han population
Dongju Su, Ximei Zhang, Hong Sui, Fuzhen Lü, Lianhong Jin, Jing Zhang
BMC Medical Genetics , 2008, DOI: 10.1186/1471-2350-9-82
Abstract: Six polymorphic sites (V4, T+1, T2, T1, S1, and Q-1) were genotyped in 128 patients with AR, 181 patients with AS, and 151 healthy controls (CTR). Genotypes were determined by the polymerase chain restriction fragment length polymorphism (PCR-RFLP) method. Data were analyzed using the chi-square test with Haploview software.The single nucleotide polymorphisms (SNPs), V4 G/C, T+1 A/G, and T1 G/A, of the ADAM33 gene may be the causal variants in AR, whereas ADAM33 V4 G/C, T2 A/G, T1 G/A, and Q-1A/G may participate in the susceptibility of AS.These results suggest that polymorphisms of the ADAM33 gene may modify individual susceptibility to AR and AS in a Chinese Han population.Rhinitis is defined as inflammation of the nasal mucosa and is characterised by nasal discharge, blockage, sneezing, and itching [1,2]. Asthma is a chronic inflammatory disorder of the airway which causes recurrent episodes of wheezing, breathlessness, chest tightness, and coughing in susceptible individuals. These episodes are usually associated with widespread, but variable airflow obstruction that is often reversible, either spontaneously or with treatment. The inflammation also causes an associated increase in existing bronchial hyper-responsiveness (BHR) to a variety of stimuli [1,2]. Epidemiologic studies have consistently shown that asthma and rhinitis often coexist in the same patients in every region of the world [3-5], suggesting the concept of 'one airway, one disease.' The basic premise is that rhinitis and asthma represent the manifestations of one syndrome in two parts of the respiratory tract [6]. In order to raise awareness of the theory of 'one airway, one disease,' the Allergic Rhinitis and Its Impact on Asthma (ARIA) Workshop Group publication proposes three considerations for patients with allergic respiratory disease [7].ADAM33 is the first reported asthma-susceptible gene identified by positional cloning [8]. ADAM33 is a complex molecule, the expression of which is largely
Genome structure of cotton revealed by a genome-wide SSR genetic map constructed from a BC1 population between gossypium hirsutum and G. barbadense
Yu Yu, Daojun Yuan, Shaoguang Liang, Ximei Li, Xiaqing Wang, Zhongxu Lin, Xianlong Zhang
BMC Genomics , 2011, DOI: 10.1186/1471-2164-12-15
Abstract: A total of 3177 new EST-SSRs developed in our laboratory and other newly released SSRs were used to enrich our interspecific BC1 genetic linkage map. A total of 547 loci and 911 loci were obtained from our EST-SSRs and the newly released SSRs, respectively. The 1458 loci together with our previously published data were used to construct an updated genetic linkage map. The final map included 2316 loci on the 26 cotton chromosomes, 4418.9 cM in total length and 1.91 cM in average distance between adjacent markers. To our knowledge, this map is one of the three most dense linkage maps in cotton. Twenty-one segregation distortion regions (SDRs) were found in this map; three segregation distorted chromosomes, Chr02, Chr16, and Chr18, were identified with 99.9% of distorted markers segregating toward the heterozygous allele. Functional analysis of SSR sequences showed that 1633 loci of this map (70.6%) were transcribed loci and 1332 loci (57.5%) were translated loci.This map lays groundwork for further genetic analyses of important quantitative traits, marker-assisted selection, and genome organization architecture in cotton as well as for comparative genomics between cotton and other species. The segregation distorted chromosomes can be a guide to identify segregation distortion loci in cotton. The annotation of SSR sequences identified frequent and rare gene ontology items on each chromosome, which is helpful to discover functions of cotton chromosomes.Cotton (Gossypium spp.) is the most important fiber crop in the world and one of the most important oilseed crops. Within the genus Gossypium, two cultivated allotetraploid species, G. hirsutum L. and G. barbadense L., account for 90% and 8% of the world cotton production respectively [1]. The construction of a molecular genetic map is a foundation in genetic dissection of economically important traits, marker-assisted selection (MAS), and map-based cloning. It provides new insights into genome structure and chromosomal a
Structure and magnetostriction of (Dy0.7Tb0.3)(0.5)Pr0.5Fex alloys (1.10 <= x <= 1.85)

Bowen WANG,Weili LIU,Guang JIN,Jianzhi BI,Ximei JIN,Zhijun GUO,Zhidong ZHANG,

材料科学技术学报 , 2000,
Abstract: The structure and magnetostriction of R0.5Pr0.5Fex, (R = Dy0.7Tb0.3, 1.10 less than or equal to x less than or equal to 1.85) alloys were investigated. It was found that the matrix of are-melting R0.5Pr0.5Fex, alloys is the (Dy, Tb, Pr) Fe-2 phase with the MgCu2-type cubic structure and the second phase is rare earth-rich phase when x<1.25. In the range of 1.40 less than or equal to x<1.55, the second phase is (Dy, Tb, Pr)Fe-3 and it becomes the main phase when x >1.55. The crystalline structure of mechanically grinding R0.5Pr0.5Fex, alloys is similar to that of the are-melted alloys. The magnetostriction of the alloys increases with increasing Fe content when x less than or equal to 1.25 and decreases when x>1.25.
The Role of Serine-Type Serine Repeat Antigen in Plasmodium yoelii Blood Stage Development
Ximei Huang, Kingsley Liew, Onguma Natalang, Anthony Siau, Neng Zhang, Peter Rainer Preiser
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0060723
Abstract: A key step for the survival of the malaria parasite is the release from and subsequent invasion of erythrocytes by the merozoite. Differences in the efficiency of these two linked processes have a direct impact on overall parasite burden in the host and thereby virulence. A number of parasite proteases have recently been shown to play important roles during both merozoite egress as well as merozoite invasion. The rodent malaria parasite Plasmodium yoelii has been extensively used to investigate the mechanisms of parasite virulence in vivo and a number of important proteins have been identified as being key contributors to pathology. Here we have utilized transcriptional comparisons to identify two protease-like SERAs as playing a potential role in virulence. We show that both SERAs are non-essential for blood stage development of the parasite though they provide a subtle but important growth advantage in vivo. In particular SERA2 appears to be an important factor in enabling the parasite to fully utilize the whole age repertoire of circulating erythrocytes. This work for the first time demonstrates the subtle contributions different protease-like SERAs make to provide the parasite with a maximal capacity to successfully maintain an infection in the host.
Increased 4-Hydroxynonenal Formation Contributes to Obesity-Related Lipolytic Activation in Adipocytes
Ximei Zhang, Zhigang Wang, Jiaxin Li, Dongfang Gu, Songtao Li, Chen Shen, Zhenyuan Song
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0070663
Abstract: Oxidative stress in adipose tissue plays an etiological role in a variety of obesity-related metabolic disorders. We previously reported that increased adipose tissue 4-hydroxynonenal (4-HNE) contents contributed to obesity-related plasma adiponectin decline in mice. In the present study, we investigated the effects of intracellular 4-HNE accumulation on lipolytic response in adipocytes/adipose tissues and underlying mechanisms. In both fully-differentiated 3T3-L1 and primary adipocytes, a 5-hour 4-HNE exposure elevated lipolytic reaction in a dose-dependent manner at both basal and isoproterenol-stimulated conditions, evidenced by significantly increased glycerol and fatty acids releases. This conclusion was corroborated by the comparable observations when the minced human visceral adipose tissues were used. Mechanistic investigations revealed that 4-HNE-stimulated lipolytic activation is multifactorial. 4-HNE exposure quickly increased intracellular cyclic AMP (cAMP) level, which was concomitant with increased phosphorylations of protein kinase A (PKA) and its direct downstream target, hormone sensitive lipase (HSL). Pre-incubation with H89, a potent PKA inhibitor, prevented 4-HNE stimulated glycerol release, suggesting that enhanced lipolytic action in response to 4-HNE increase is mediated mainly by cAMP/PKA signal pathway in adipocytes. In addition to activating cAMP/PKA/HSL pathway, 4-HNE exposure also suppresses AMP-activated protein kinase (AMPK), a suppressive pathway for lipolysis, measured by both Western blotting for phosphorylated form of AMPK and ELISA for enzyme activity. Furthermore, 5-Aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside (AICAR), a pharmacological AMPK activator, alleviated 4-HNE-induced lipolysis, suggesting that AMPK suppression also contributes to 4-HNE elicited lipolytic response. In conclusion, our findings indicate that increased intracellular 4-HNE accumulation in adipocytes/adipose tissues contributes to obesity-related lipolytic activation.
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