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排序方式: 共有2413条查询结果,搜索用时 156 毫秒
1.
To identify viruses in Henan tobacco-planting areas, from 2015 to 2017 and 2019, 288 symptomatic tobacco samples were collected and then subjected to small RNA sequencing. Results showed that at least 7 viruses were detected from these samples which including four previously reported viruses, cucumber mosaic virus (CMV), tobacco mosaic virus (TMV), potato virus Y (PVY) and tobacco vein banding mosaic virus (TVBMV). Other three viruses, wild tomato mosaic virus (WTMV), brassica yellows virus (BrYV), and cycas necrotic stunt virus (CNSV) were firstly detected in Henan province. However, tobacco etch virus (TEV) and tobacco ringspot virus (TRSV) were not detected from these samples. In addition, CMV, TMV, PVY, TVBMV, and BrYV were the dominant viruses infecting tobacco in Henan Province.  相似文献   
2.
刘宁  赵国  刘刚 《农业工程学报》2021,37(18):232-243
溶出伏安法具有分析速度快、成本低、灵敏度高等优点被广泛应用于检测土壤重金属含量,但在检测土壤重金属时,溶出伏安检测精度会受到多方面因素的影响。该文在介绍溶出伏安法工作原理的基础上,从伏安参数、试验条件和土壤物质成分三方面阐述溶出伏安法检测土壤Pb2+和Cd2+为的影响因素,解析各因素的影响机理,归纳影响削弱方法的研究进展。研究结论为:方波脉冲阳极溶出伏安法最常用于检测土壤Pb2+和Cd2+,伏安参数包括脉冲幅值、电压增量和脉冲频率,试验条件包括沉积时间、沉积电压和支持电解质种类及其pH值,土壤成分主要干扰因素包括非目标重金属和有机质。针对伏安参数和试验条件的影响可以设计优化试验有效削弱。针对非目标重金属和有机质的干扰影响,目前研究还没有提出有效的削弱方法。最后,展望了溶出伏安法检测土壤重金属的未来发展方向。  相似文献   
3.
基于传统的酸性酚—异硫氰酸胍—氯仿一步提取法,比较分析多种优化操作步骤,摸索出一种高质量提取体质量为80~150 g草鱼肠系膜脂肪组织总RNA的改良方法。试验结果显示,相较于肝脏、脾脏、肠道等脏器组织,草鱼肠系膜脂肪组织RNA丰度低,且极易在样品前处理阶段出现顽固性降解问题。探索发现,将取样量增至约30 mg,可提升RNA产量以满足常规试验需求。针对降解难题,改良常规的样品前处理技术流程,采用鲜样液氮速冻,冻样直接放入TRIzol试剂中裂解,并即刻进行长时间机械匀浆,时长约3 min等核心操作步骤,可显著降低脂肪组织样品RNA的降解。Agilent生物分析仪检测结果显示,改良方法提取的草鱼肠系膜脂肪组织RNA完整度高,关键RIN值为8.7~9.0。研究推测,长时间机械匀浆所形成的持续剪切冲击力或许有助于TRIzol试剂中的异硫氰酸胍等成分突破油滴阻碍而有效抑制内源性RNA酶。本方法提取的草鱼脂肪组织总RNA质量可满足高通量转录组测序要求。  相似文献   
4.
Invasive alien species(IAS) are species whose introduction to areas outside of their native range cause harm to economics, biodiversity, and the environment. Understanding the genetic basis of invasiveness is critical for preventing invasion by an alien species and managing IAS with eco-friendly control methods. In addition, uncovering the genomic features of IAS is essential for accurately predicting invasiveness. However, even though increasing efforts have been devoted to sequencing the genomes of IAS, there is still not an integrated genome database for the invasive biology community. Here, we first determined a list of invasive plants and animals by mining references and databases. Then, we retrieved the genomic and gene data of these IAS, and constructed a database, Invasion DB. Invasion DB encompasses 131 IAS genomes, 76 annotated IAS assemblies, and links these data to conventional functions such as searching for gene coding sequences and Pfam, KEGG, NR annotations, BLAST server, JBrowse, and downloads services. Next, we analyzed 19 invasivenessrelated gene families which confer invasiveness in insects. To study the roles of noncoding RNA in invasiveness, we also annotated 135 494 mi RNAs, 89 294 r RNAs, and 2 671 941 t RNAs from these IAS. In summary, Invasion DB is useful for studying the invasiveness at the genomic level, and thus helps to develop novel management strategies to control IAS.  相似文献   
5.
The potato leafroll virus (PLRV) P0 protein (P0PL) is a suppressor of RNA silencing. In this study, we showed that P0 protein from an Argentinian isolate of PLRV (P0PL-Ar) has an additional activity not described for other PLRV or P0 proteins from poleroviruses. Besides reporting that P0PL-Ar displays both local and systemic silencing suppressor activity, we demonstrated, for the first time, that P0PL-Ar impedes accumulation of dsRNA-derived siRNAs. We also showed that P0PL-Ar interacts with Solanum tuberosum SKP1 orthologue (StSKP1) and triggers destabilization of ARGONAUTE 1 (AGO1) and that these actions are mediated by the F-box-like domain. A mutant in the GW/WG motif within the P0PL-Ar F-box-like motif lost the suppression activity, the interaction with StSKP1 and abolished AGO1 decay. Interestingly, a mutant in the L76/P77 residues within the P0PL-Ar F-box-like motif, which lost the suppression activity and the interaction with StSKP1, retained the capacity to enable AGO1 decay. Thus, unlike other P0 proteins of previously characterized poleroviruses, P0PL-Ar seems to have a dual activity, according to the findings of this study. This protein would act at both an upstream and a downstream step of the RNA silencing pathway: upstream of Dicer-like enzyme (DCL)-mediated primary siRNA production and downstream at the RNA-induced silencing complex (RISC) complex level. Our results contribute to the understanding of the different ways PLRV P0 proteins function as silencing suppressors.  相似文献   
6.
Peritrophic matrix/membrane (PM) critically prevents the midgut of insects from external invasion by microbes. The proteins in the peritrophic membrane are its major structural components. Additionally, they determine the formation and function of this membrane. However, the role of PM proteins in immune regulation is unclear. Herein, we isolated a novel PM protein (MdPM-17) from Musca domestica larvae. Further, the function of MdPM-17 in regulating host innate immunity was identified. Results showed that the cDNA of MdPM-17 full is 635 bp in length. Moreover, it consists of a 477-bp open reading frame encoding 158 amino acid residues. These amino acid residues are composed of two Chitin-binding type-2 domain (ChtBD2) and 19 amino acids as a signal peptide. Moreover, tissue distribution analysis indicates that MdPM-17 was enriched expressed in midgut, and moderate levels in the fat body, foregut, and malpighian tubule. Notably, MdPM-17 recombinant protein showed high chitin-binding capacity, thus belongs to the Class III PM protein group. MdPM-17 protein silencing via RNA interference resulted in the expression of antimicrobial peptide (defensin, cecropins, and diptericin) genes, and this occurred after oral inoculation with exogenous microbes Escherichia coli (Enterobacteriales:Enterobacteriaceae), Staphylococcus aureus (Bacillales:Staphylococcaceae), and Candida albicans (Endomycetales:Saccharomycetaceae)). Therefore, all the antimicrobial peptide (AMP) gene expression levels are high in MdPM-17-depleted larvae during microbial infection compared to controls. Consequently, these findings indicate that MdPM-17 protein is associated with the antibacterial response from the housefly.  相似文献   
7.
8.
RNA viruses rapidly mutate, which can result in increased virulence, increased escape from vaccine protection, and false-negative detection results. Targeted detection methods have a limited ability to detect unknown viruses and often provide insufficient data to detect coinfections or identify antigenic variants. Random, deep sequencing is a method that can more fully detect and characterize RNA viruses and is often coupled with molecular techniques or culture methods for viral enrichment. We tested viral culture coupled with third-generation sequencing for the ability to detect and characterize RNA viruses. Cultures of bovine viral diarrhea virus, canine distemper virus (CDV), epizootic hemorrhagic disease virus, infectious bronchitis virus, 2 influenza A viruses, and porcine respiratory and reproductive syndrome virus were sequenced on the MinION platform using a random, reverse primer in a strand-switching reaction, coupled with PCR-based barcoding. Reads were taxonomically classified and used for reference-based sequence building using a stock personal computer. This method accurately detected and identified complete coding sequence genomes with a minimum of 20× coverage depth for all 7 viruses, including a sample containing 2 viruses. Each lineage-typing region had at least 26× coverage depth for all viruses. Furthermore, analyzing the CDV sample through a pipeline devoid of CDV reference sequences modeled the ability of this protocol to detect unknown viruses. Our results show the ability of this technique to detect and characterize dsRNA, negative- and positive-sense ssRNA, and nonsegmented and segmented RNA viruses.  相似文献   
9.
为了解决农业设备位移的宽量程、高灵敏度非接触测量问题,提出一种基于Peanut-shape迈克尔逊干涉结构的非接触式光纤位移传感器。分析了光纤Peanut-shape迈克尔逊干涉原理,设计了将磁场与Peanut-shape结构形成的全纤式迈克尔逊干涉相结合的传感器结构,并通过磁场仿真,得到磁场强度曲线。建立了传感器应变标定系统和位移测试系统。试验结果表明:Peanut-shape迈克尔逊干涉的光纤传感器应变灵敏度达到1. 82 pm/με,是普通光纤的1. 5倍,线性度为0. 997;位移测试得到的光谱曲线与磁场仿真曲线结果一致,可以实现位移的测量,且线性拟合度达到0. 999。  相似文献   
10.
人为干扰会对野生动物种间关系、个体适合度、群落结构和繁殖成功率等产生中长期的影响。因此,研究野生动物反干扰行为对于我们认识该物种对其生境的行为适应和进化机制具有重要意义。2017年11—12月在内蒙古贺兰山国家级自然保护区内通过建立多元逻辑斯蒂回归模型研究了岩羊(Pseudois nayaur)、马鹿(Cervus elaphus)的反干扰策略,本研究共设置33条样线,记录了10种在人为干扰下可能会影响岩羊、马鹿反应行为的变量,经模型分析发现影响岩羊反应行为的变量有5种,影响马鹿反应行为的变量有4种,共同影响因子分别是干扰源、性别、头的朝向和地形特征,而植被类型则只对岩羊产生影响。最后根据逻辑模型得出的数据计算发生比,从而了解各个分类变量与反应行为的关系。  相似文献   
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