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1.
以罗布泊盐湖沉积物为研究对象,以环境磁学为主要研究方法,探讨罗布泊盐湖沉积物磁性特征的影响因素和环境意义。根据磁性特征可将罗布泊LOP1剖面沉积物分为两类:磁铁矿主导和铁硫化物(胶黄铁矿和黄铁矿)主导。磁铁矿主要来源于物源区塔里木盆地。胶黄铁矿和黄铁矿是早期还原成岩作用的产物,对磁性特征产生显著影响,胶黄铁矿主导层具有明显较高的χ、SIRM、χARM、χARM/χ和S-300 mT,黄铁矿相反。有机质供应增加是罗布泊盐湖沉积早期成岩作用的触发因素,中晚全新世以来冷事件期间塔里木盆地湿度改善,有机质供应增加,促使了早期成岩成因的自生铁硫化物生成。  相似文献   
2.
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   
3.
4.
Beet yellows virus (BYV), beet mild yellowing virus (BMYV), beet chlorosis virus (BChV), and beet mosaic virus (BtMV) cause virus yellows (VY) disease in sugar beet. The main virus vector is the aphid Myzus persicae. Due to efficient vector control by neonicotinoid seed treatment over the last decades, there is no current knowledge regarding virus species distribution. Therefore, Europe-wide virus monitoring was carried out from 2017 to 2019, where neonicotinoids were banned in 2019. The monitoring showed that closterovirus BYV is currently widely spread in northern Europe. The poleroviruses BMYV and BChV were most frequently detected in the northern and western regions. The potyvirus BtMV was only sporadically detected. To study virus infestation and influence on yield, viruses were transmitted to sugar beet plants using viruliferous M. persicae in quadruplicate field plots with 10% inoculation density simulating natural infection. A plant-to-plant virus spread was observed within 4 weeks. A nearly complete infection of all plants was observed in all treatments at harvest. In accordance with these findings, a significant yield reduction was caused by BMYV and BChV (−23% and −24%) and only a moderate reduction in yield was observed for BYV (−10%). This study showed that inoculation at low densities mimics natural infection, and quick spreading induced representative yield effects. Within the background of a post-neonicotinoid era, this provides the basis to screen sugar beet genotypes for the selection of virus tolerance/resistance and to test the effectiveness of insecticides for the control of M. persicae with a manageable workload.  相似文献   
5.
  1. Humanity is facing a biodiversity crisis, with freshwater-associated biodiversity in a particularly dire state. Novel ecosystems created through human use of mineral resources, such as gravel pit lakes, can provide substitute habitats for the conservation of freshwater and riparian biodiversity. Many of these artificial ecosystems are subject to a high intensity of recreational use, however, which may limit their biodiversity potential.
  2. The species richness of several taxa (plants, amphibians, dragonflies, damselflies, waterfowl, and songbirds) was assessed and a range of taxonomic biodiversity metrics were compared between gravel pit lakes managed for recreational fisheries (n = 16) and unmanaged reference lakes (n = 10), controlling for non-fishing-related environmental variation.
  3. The average species richness of all the taxa examined was similar among lakes in both lake types and no substantial differences in species composition were found when examining the pooled species inventory. Similarly, there were no differences between lake types in the presence of rare species and in the Simpson diversity index across all of the taxa assessed.
  4. Variation in species richness among lakes was correlated with woody habitat, lake morphology (surface area and steepness), and land use, but was not correlated with the presence of recreational fisheries. Thus, non-fishing-related environmental variables had stronger effects on local species presence than recreational fisheries management or the presence of recreational anglers.
  5. Collectively, no evidence was found that anglers and recreational fisheries management constrain the development of aquatic and riparian biodiversity in gravel pit lakes in the study region; however, the conservation of species diversity in gravel pit lakes could benefit from an increasing reliance on habitat enhancement activities.
  相似文献   
6.
The presence and transformations of nitrogen (N) in the environment depend on a variety of environmental factors but are also strongly influenced by anthropogenic activities such as modern agriculture. Understanding N transformations within the context of agricultural systems is crucial for efficient use thereof. The aim of this study was to investigate the changes in concentration of N forms (ammonium, nitrite, nitrate and organic N) within an aquaponic system, a modern agricultural system, in order to obtain insights into environmental pressures influencing N transformation processes. By measuring the concentrations of the individual N compounds, complemented by the determination of abiotic parameters and other relevant nutrients within the system water at 13 sampling points, significant differences between compartments that build up an aquaponic system could be demonstrated. These differences were attributed to individual microenvironments specific to the aerobic loop, anaerobic loop and radial flow settler as a connection between the two, shaping the microbial processes within the aquaponic system.  相似文献   
7.
猪流行性腹泻病(porcine epidemic diarrhea,PED)是一种高度接触性肠道传染性疫病,主要危害1周龄以内的仔猪,仔猪感染死亡率高达100%,是目前危害世界养猪业的主要疫病之一。本研究旨在制备针对猪流行性腹泻病毒S蛋白的特异性纳米抗体并鉴定其结合活性。作者原核表达并纯化PEDV S1蛋白,将纯化后的PEDV S1重组蛋白免疫双峰驼,第4次免疫后分离其外周血淋巴细胞,提取淋巴细胞RNA,反转录得到cDNA,通过巢式PCR扩增VHH片段,并构建至pCANTAB-5E载体中,电转化至TG1感受态细胞,得到VHH噬菌体抗体展示文库;随后,对构建的噬菌体抗体展示文库进行救援和3轮富集,利用噬菌体展示技术从中筛选针对PEDV S蛋白纳米抗体,通过ELISA验证筛选的纳米抗体的特异性和结合力。通过Western blot和间接免疫荧光验证纳米抗体与PEDV的结合活性。结果显示:成功表达并纯化PEDV S1蛋白,经4次免疫后,双峰驼血清中的特异性抗体效价达到了1∶256 000。构建的噬菌体展示文库的库容量为2.1×107,阳性率85%;对噬菌体展示文库3轮的淘选富集后,最终筛选出6株氨基酸序列不同的纳米抗体,ELISA结果显示,6株纳米抗体均对PEDV S1重组蛋白具有良好的结合力与特异性。随后验证了Nb3能够与PEDV结合,表明其具有良好的活性。成功筛选到针对PEDV S1蛋白的特异性纳米抗体,所筛选纳米抗体有望用于PED的诊断和治疗,同时为PEDV的致病机制研究提供抗体材料。  相似文献   
8.
目的】检测新疆南疆7个县/市瓜类褪绿黄化病毒(Cucurbit chlorotic yellows virus, CCYV),进行系统发育分析,为新疆南疆CCYV预警和防控提供参考。【方法】于2019年,从中国新疆南疆7个县/市采集带有黄化特征的51份甜瓜叶片样品,RT-PCR进行CCYV的检测,进行特异性片段的克隆、测序和系统发育分析。【结果】中国新疆巴楚县、阿克苏市、莎车县、伽师县、疏勒县、疏附县均未检测到CCYV,而洛浦县的13份样本中,8份检出为CCYV阳性,检出率为61.53%,洛浦县CCYV特异性片段克隆测序获得了685 bp的核酸序列,与GenBank中的CCYV分离物外壳蛋白(Coat protein, CP)的一致性达到100%。所得序列与中国新疆(吐鲁番)、中国其他省、苏丹、日本、塞浦路斯、黎巴嫩的CP基因聚在I组(Group),沙特阿拉伯的分离物聚在Ⅱ组,伊朗的分离物聚在Ⅲ组。【结论】CCYV在中国新疆南疆洛浦县甜瓜产区发生,与中国新疆吐鲁番、中国其他省及周围国家的CCYV分离物亲缘关系很近,且群体遗传变异很小。  相似文献   
9.
病毒侵染直接影响草莓的生长发育及果实品质,快速检测及鉴定病毒是病毒防治的前提。本研究以‘丰香’草莓和‘哈尼’草莓为试材,利用小RNA(sRNA)测序结合RT-PCR技术对2种栽培草莓品种中存在的病毒进行了研究。对sRNA测序结果进行组装和注释,结果表明:在混合样品中共有242个contigs比对到5种草莓病毒,分别为草莓白化病毒(strawberry pallidosis associated virus,SPaV)、草莓镶脉病毒(strawberry vein banding virus,SVBV)、草莓斑驳病毒(strawberry mottle virus,SMoV)、草莓毛形病毒3(strawberry crinivirus 3,SCrV 3)和草莓毛形病毒4(strawberry crinivirus 4,SCrV 4)。利用RT-PCR技术对sRNA测序结果进行验证,结果表明:SMoV、SVBV和SCrV 3在‘丰香’草莓和‘哈尼’草莓中均检测到,而SPaV和SCrV 4只在‘哈尼’草莓样品中检测到。本研究利用sRNA测序技术鉴定了2个草莓品种中存在的病毒,首次在我国生产的同一个草莓品种中检测到5种病毒,为草莓病毒的检测和防控提供了新的思路。  相似文献   
10.
边界病(border disease,BD)是由边界病毒(BDV)引起绵羊和山羊的一种病毒性疾病,临床症状表现为母羊不孕、流产和死胎,以及羔羊体型异常,多毛,震颤,因此又称"多毛震颤病","茸毛症"。该病的主要传播途径是垂直传播,持续性感染的羔羊是该疾病在绵羊中传播的潜在主要传染源。山羊相对绵羊感染症状相对较轻,主要表现为流产。目前尚无公认有效的BD疫苗,做好生物安全防控,严格饲养管理,及时对疑似染病动物特别是持续性病毒血症绵羊的检测和淘汰是防治本病的重要措施。现对该病的流行现状、病原学、流行病学、鉴别诊断和预防控制等方面的研究进展进行综述,旨在为研究人员及养殖户加强对BD的认识,做好疾病的相关预防工作,减少经济损失提供参考。  相似文献   
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