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Bryophyte-cyanobacteria symbioses and their nitrogen fixation capacity-A review
No full text苔藓-蓝藻共生体(BCS)能固氮,是养分贫瘠地区森林氮输入的不可忽视的来源。BCS关系与固氮能力研究为科学认识生态系统氮输入与氮循环过程和机理提供了新的视角和有效途径,具有重要的理论价值。然而,BCS关系、固氮作用与机理的研究迄今未受到足够关注,报道较少,认识仍然是零星而片段化的。基于系统查阅的相关文献,该文综述了BCS的种类组成与共生关系类型、固氮能力及所固定氮的去向及其影响因素和作用机理,指出了存在的问题及需要深入关注和亟待突破的4个研究方向
Introduction and imitative wild cultivation of Dendrobium nobile in north of Sichuan
No full text为探讨金钗石斛是否适合川北地区种植,本研究将合江金钗石斛引种到秦巴山区栽培.对引种两年后大棚和林下两种仿野生栽培模式下的金钗石斛进行测量和评估.林下贴石栽培组可达98.73%的存活率和平均每株1.41个新芽;林下栽培组的茎长和叶长约9.5cm和7.2cm;而大棚栽培组分别只有6.6cm和5.1cm;林下栽培组一年生和两年生叶片的叶绿素含量分别为37.3SPAD和26.3SPAD,与大棚栽培组相比无显著差异;林下栽培组的遮光率和大棚栽培组相比无显著差异,但遮光率的SD值在林下栽培组和大棚栽培组分别为26.63和13.31.试验表明,金钗石斛在川北的最佳引种时间为每年春季,林下条件较为适宜,以林下贴石栽培效果最好
Microbial community of maize straw and cabbage waste under different storage conditions
No full text采用Illumina Miseq高通量技术分析不同温度和贮存方式下玉米秸杆(IO)和白菜废弃物(IA)贮存30 d时的微生物群落.设置低温(O)、中温(R)和高温(H)3种温度;每种温度条件均设有秸杆单贮(O)、白菜单贮(A)和二者混贮(X)3个处理组.结果显示,IO原料附着细菌主要包括变形菌门(Proteobacteria)(65.26%)和厚壁菌门(Firmicutes)(33.78%),IA主要包括Proteobacteria(80.23%)和拟杆菌门(Bacteroidetes)(18.57%).贮存30 d后在属水平上,IO主要包括肠杆菌(Enterobacter)(47.11%)、肉食杆菌(Carnobacterium)(27.71%)和泛菌(Pantoea)(10.14%)等;IA主要包括假单孢菌(Pseudomonas)(48.40%)、Pantoea(17.10%)和黄杆菌(Flavobacterium)(16.26%)等; IA中几乎不含乳酸菌,IO中乳酸菌丰度约28.71%. IO组低、高温单贮时主要包括Enterobacter(21.76%和35.87%)、 Carnobacterium(40.42%和27.29%)和Pseudomonas(18%和26.99%),中温单贮时主要包括Enterobacter(66.72%);IA中、高温单贮时主要包括乳杆菌(Lactobacillus)(80.07%和74.63%),低温单贮时主要包括Lactobacillus(28.43%)、耶尔森氏鼠疫杆菌(Yersinia)(19.50%)和Enterobacter(17.13%);二者低、中温混贮时主要包括Lactobacillus(52.03%和53.52%)、Enterobacter(5.98%和11.65%)和Carnobacterium(12.98%和10.65%),高温混贮时主要包括Enterobacter(70.57%).综上表明,高通量测序技术全面反映了IO和IA在不同贮存条件下细菌群落的组成及丰度信息,白菜中高温单独贮存、秸秆/白菜中低温混合贮存时乳酸菌占优势
Combined effects of cropping types and simulated extreme precipitation on the community composition and diversity of soil macrofauna in the eastern Qinghai-Tibet Plateau
No full textPurposeExtreme precipitation as global change greatly affects above- and below-ground biodiversity. Soil macrofauna play a key role in the agroforestry ecosystem processes. Extreme precipitation might negatively impact soil macrofauna by changing soil water content. Particularly, whether cropping types are beneficial to alleviate response of soil macrofauna to extreme precipitation remains unexplored.Materials and methodsEffects of simulated extreme precipitation of 1month on soil macrofauna were studied under Chinese prickly ash (Zanthoxylum bungeanum) intercropped with soybean (Glycine max), Chinese prickly ash intercropped with sweet pepper (Capsicum annuum), and Chinese prickly ash monoculture. Soil macrofauna and soil samples were collected in three soil depths (0-10, 10-20, and 20-30cm) per plot. The abundance, diversity, and vertical distribution of soil macrofauna were analyzed for each sample at genus and trophic level. Each sieved soil sample was analyzed for soil water content, soil nitrate nitrogen (NO3--N), ammonium nitrogen (NH4+-N) and organic matter. Descriptive statistics and significance tests on raw data were carried out using the SPSS 16.0 software at P<0.05.Results and discussionA total of 502 soil macrofauna individuals were observed, and belonged to 14 genera, and consisted mainly of earthworms, arthropods. The richness, density, and biomass, as well as vertical distribution of total soil macrofauna were unaffected by extreme precipitation. Only Eisenia density and biomass were significantly decreased by extreme precipitation. The plots intercropped with soybean had higher density, biomass, and richness than the plots intercropped with sweet pepper and prickly ash monoculture. Cropping types significantly influenced density of total soil macrofauna under control condition but not extreme precipitation treatment. The abundance of total soil macrofauna was significantly and positively related to soil NH4+-N, total soil inorganic N, and soil organic matter.ConclusionsOur results suggest that the impacts of cropping types rather than extreme precipitation on soil macrofauna abundance, diversity, and vertical distribution are significant. However, extreme precipitation changes the response of soil macrofauna to cropping types
Research progress on the responses of soil respiration components to climatic warming
No full text气候变暖正在深刻地改变全球碳循环过程.土壤呼吸作为全球碳循环的重要环节,连接着植物-土壤-微生物之间的碳转移过程.土壤呼吸可分为异养呼吸和根源呼吸(根系呼吸和根际微生物呼吸)等组分.土壤呼吸各组分的发生部位与利用的有机碳源不同,其对气候变暖的响应可能存在显著差异.然而,目前的研究还不能完全实现土壤呼吸各组分的精确区分和量化,气候变暖对土壤呼吸各组分的影响及其具体机制仍存在很多悬而未决的问题,这极大地限制了人们对土壤碳循环评估的精确性以及对气候变暖背景下陆地生态系统碳收支格局变化的认识.本文系统综述了目前国内外土壤呼吸组分区分技术,分析了土壤呼吸组分区分的研究结果,并论述了土壤呼吸各组分对气候变暖的响应研究进展.提出仍需发展新的土壤呼吸组分区分技术或者改进和创新现有技术,未来的研究重点应放在精确区分野外条件下根源呼吸组分,同时开展土壤呼吸组分对多种环境因子变化的响应研究,以期更全面地认识土壤碳循环过程以及全球变化背景下陆地生态系统碳收支的变化趋势
Oilseed rape cultivation increases the microbial richness and diversity in soils contaminated with cadmium
No full textThis investigation aimed to estimate and characterize the microbial diversity in soils with cadmium (Cd) at different concentrations and to evaluate whether Brassica napus can restore the soil microbial diversity. We conducted the pot experiment to analyze the composition of microbial communities in the soil contaminated with 0, 1, and 2 mg/kg Cd, as well as planted with oilseed rape. The bacterial and fungal communities were characterized via next-generation sequencing based on 16S and 18S rRNA gene fragments pyrosequencing, respectively. The results show that cadmium contamination decreased both the microbial richness and diversity in the soil, while the cultivation of oilseed rape increased the richness and diversity. In bacteria, Proteobacteria was the most abundant phylum in all the samples accounting for 39.62 to 46.14%, followed by Bacteroidetes, Actinobacteria, and Chloroflexi. These phyla collectively comprised more than 70% of all phyla. Ascomycota was the most abundant phylum in all samples in fungi (89.65 to 96.00%), and it was the only phylum whose abundance was increased with the rise of Cd concentration. Microbial richness and diversity were affected by the combined action of Cd and B. napus. Cd contamination decreased the microbial richness and diversity, while cropping with oilseed rape increased the microbial richness and diversity, which alleviated the deleterious effect of the Cd pollution in soils. These reflected that oilseed rape played a positive role in maintaining species diversity of microorganism from the side
Effects of influent loads on performance and microbial community dynamics of aerobic granular sludge treating piggery wastewater
No full textBACKGROUNDUnderstanding how influent loads affect the microbial community may promote applications of aerobic granular sludge (AGS). Herein, performance and microbial community dynamics of the AGS were assessed with stepwise increasing influent loads. RESULTSAGS exhibited good structure stability and effective removal efficiency; when the influent load increased from 6.5 kg COD m(-3) d(-1) (0.255 NH4+-N m(-3) d(-1)) to 10.1 kg COD m(-3) d(-1) (0.455 kg NH4+-N m(-3) d(-1)). COD and NH4+-N removal efficiencies reached 97.1-97.9% and 84.5-98%, respectively. As indicated from the PCR-DGGE results, the microbial community and dominant species in the AGS also gradually evolved along with the increase of influent loads. A coincidence was observed, namely, three main distinct clusters of the phylogenetic tree appeared respectively in the three stages of influent loads. The microbial diversity attained a maximum in the medium loads stage. The identified bacteria mainly belonged to Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes. The dominant species were responsible for the AGS stability and pollutant removal. CONCLUSIONVariation in the influent load strongly affected the microbial community dynamics, and hence the AGS performance. These results and understanding could lead to potential improvements in guiding AGS wastewater treatment. (c) 2017 Society of Chemical Industr
Glutaredoxin-1 Silencing Induces Cell Senescence via p53/p21/p16 Signaling Axis
No full textGlutaredoxin-1 (Grxl) catalyzes deglutathionylation with glutathione as a cofactor. Accumulating evidence indicates important roles for Grxl and S-glutathionylation in the aging process; however, further exploration of Grxl-regulated cellular processes is important to understand the functions of Grxl in aging. In the present study, we constructed stable Grxl knockdown or overexpression human cell lines. Grxl silencing significantly decreased the cellular ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) (GSH/GSSG ratio), resulting in excessive reactive oxygen species (ROS) accumulation, whereas Grxl overexpression decreased cellular ROS levels. Grxl silencing also increased glutathionylation of DJ-1 and HSP60, contributing to decreased mitochondrial spare respiration capacity and ATP production. We applied quantitative proteomics to identify differentially expressed proteins between Grxl knockdown and control cells and showed that Grxl silencing inactivated DNA replication and damage repair pathways. p53 signaling was activated by Grxl silencing, which inhibited the CDK4-mediated G1-S transition, resulting in GI phase cell-cycle arrest and cell senescence, a known hallmark of aging. Taken together, our results indicate that Grxl regulates DNA replication and damage repair processes and is a potential therapeutic target for aging-related diseases
Do longer root hairs improve phosphorus uptake? Testing the hypothesis with transgenic Brachypodium distachyon lines over-expressing endogenous RSL genes
No full textMutants without root hairs show reduced inorganic orthophosphate (Pi) uptake and compromised growth on soils when Pi availability is restricted. What is less clear is whether root hairs that are longer than wild-type provide an additional benefit to phosphorus (P) nutrition. This was tested using transgenic Brachypodium lines with longer root hairs. The lines were transformed with the endogenous BdRSL2 and BdRSL3 genes using either a constitutive promoter or a root hair-specific promoter. Plants were grown for 32 d in soil amended with various Pi concentrations. Plant biomass and P uptake were measured and genotypes were compared on the basis of critical Pi values and P uptake per unit root length. Ectopic expression of RSL2 and RSL3 increased root hair length three-fold but decreased plant biomass. Constitutive expression of BdRSL2, but not expression of BdRSL3, consistently improved P nutrition as measured by lowering the critical Pi values and increasing Pi uptake per unit root length. Increasing root hair length through breeding or biotechnology can improve P uptake efficiency if the pleotropic effects on plant biomass are avoided. Long root hairs, alone, appear to be insufficient to improve Pi uptake and need to be combined with other traits to benefit P nutrition
Effects of Nutrient Input on Soil Nitrogen Cycle in Winter in the Alpine Zone
No full textMicrobial activity is rapidly reduced due to the decrease in temperature, but does not completely cease in the cold season. The snowpack in late winter insulates the soil and further increases soil temperature, allowing microbes to remain active and inducing a shift in the nature of N processing in alpine areas. Microbes need both carbon (C) and nitrogen (N) for their growth and metabolism and the scarcity of either will limit their activity. So soil available N pools and N cycling were closely linked to the C and N of the soil. Many previous studies showed the different results in different regions. Some of the results were considered to be C limited, some considered to be N limited, and also some considered to have little impact. However, which factor limited soil microbes and controlled soil N mineralization was not clear in the alpine belt of the eastern Qinghai Tibet Plateau. In present study, the effects of litter addition in situ and nutrient factors input in laboratory on soil mineral N pools and N mineralization in the eastern Qinghai Tibet Plateau were explored. A significant decrease in soil MBN content, NH4+-N content, increase in soil NO3-N content and net N mineralization, and no change in DON contents were observed with litter input. Direct input of C in laboratory decreased mineral N pools, while mineral N contents increased when N was added. The results suggested that the soil N cycling was influenced by the addition of available C, and the C-limitation occurs in winter in the Eastern Qinghai Tibet Plateau