石蜡油对离子注入动物细胞真空环境的保护效应初探

利用石蜡油的高效护水功能进行动物细胞(HeLa细胞)的真空及注入保护,研究了不同的预处理时间对细胞活性的影响,并将石蜡油浸泡细胞2 m in~6 m in选为最佳保护时间。当细胞经过2 m in~6 m in的预处理后再进行真空、注入,结果显示成活率大幅度提高。     

绿色太阳鱼的生物学习性

对绿色太阳鱼(Lepomis cyanellus)的食性、生活习性、对环境的适应性、生长和繁殖特性进行了研究。绿色太阳鱼为温和肉食性鱼类。对温度适应性广。体长与体重的相关关系为:W=0.375 3L3.194 9,同龄雄鱼大于雌鱼。135~180日龄性成熟,为多次产卵类型,卵沉性、粘性,绝对怀卵量与体重呈直线正相关:Y=0.551 2 0.252 3X,相对生殖力为260粒/g,胚胎发育阶段所需积温为950℃.h.。     

林下养鸡年限对杨树人工林土壤磷素形态和生物有效性的影响

林下养殖是一种经济有效的林地空间利用方式,但长期高负载的林下养殖对林地土壤性状究竟产生何种影响,目前尚无定论.以不同林下养鸡年限(0年、1年、3年和5年)的美洲黑杨(Populus deltoides)人工林为对象,采用Hedley磷素分级法,分析其林地土壤的磷素组成和形态变化,探讨林下养鸡年限对土壤磷库特征及其生物有...     

我国D2-43病毒株PrM-E基因的重组SFV的制备及生物学鉴定

 为构建含PrM E基因的重组SFV病毒 ,将含我国登革 2型病毒PrM E基因的SFV表达载体和辅助载体DNA线性化后 ,进行体外转录 .然后将获得的 2种RNA转录物共转染BHK2 1细胞 ,以RT PCR法证明转染后的细胞培养上清中含有重组SFV .进一步将该重组病毒经蛋白酶激活后可使BHK2 1细胞产生细胞病变 ,并且以间接免疫荧光法在感染细胞内可检测到登革 2型病毒所特有的蛋白 .含我国登革 2型病毒PrM E基因的重组SFV的获得 ,为进一步观察该重组病毒的免疫原性奠定了基础 ,从而为登革新型疫苗的研制提供新途径     

里氏木霉翻转酶DRS2对木质纤维素降解酶基因表达及分泌的影响

[目的]本研究以工业生产菌株里氏木霉为研究对象,鉴定翻转酶基因drs2对其纤维素酶表达及分泌的影响.[方法]首先通过BLAST序列比对,从里氏木霉中鉴定出翻转酶基因drs2,并通过同源重组的方法在里氏木霉中构建了drs2基因的敲除菌株△drs2.对△drs2菌株及其对照株在不同碳源上的生长发育、蛋白分泌、纤维素酶及半纤...     

沙田柚RING-H2 finger基因的生物信息学分析

为探讨沙田柚自交不亲和性的机理,利用高通量测序技术对沙田柚自交和异交花柱进行转录组测序,通过差异分析得到了沙田柚RING-H2 finger基因序列。采用生物信息学方法,对其编码的蛋白质从序列特征、理化性质、跨膜结构域、高级结构以及功能域等方面进行了预测和分析。结果表明:该基因全长为845 bp,开放阅读框(ORF)全长为387 bp,编码128个氨基酸,编码蛋白质的分子量为13.61 KDa,理论等电点为4.26;该蛋白质含有一个植物RING-H2 finger蛋白家族的保守结构域,为疏水性不稳定蛋白。氨基酸序列分析表明,其编码的氨基酸与甜橙(Cs4g15340.1)RING-H2 finger蛋白的相似度为98%。这些分析结果可为今后深入研究该蛋白的结构特征和功能提供参考。     

Constructing Structural Isomers to Reveal and Enhance Lithium Storage in a Conducting Polymer

Organic electrodes have gained great interest for batteries. Conducting polymers have the merits of high conductivity, and hence are attempted as electrode materials in batteries as soon as their discoveries. However, conducting polymers showe poor electrochemical performance and are baring vague charge storage mechanisms. Here, a strategy is reported to reveal the charge storage mechanisms of conducting polymers by constructing isomers and using polypyridines as a proof-of-concept. Polypyridines are rarely studied and its redox activity is still not clear. The results indicate that every pyridine ring can accept one electron and the dimer unit with adjacent C═N groups can gain one more electron through chelation effects with Li ions. The electron transferred number and the chelation effects can be quantified by the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectroscopy and verified by density functional theory (DFT) calculations. As a result, one of the polypyridine isomers delivers the highest capacity of 504 mAh g⁻¹ after deducting the contribution of conductive additives. This work provides a universal way to reveal the charge storage mechanism and highlights the significance of adjacent active centers to form chelation with Li ions and hence enhance the performance of organic batteries.     

Prevalence of bovine tuberculosis in dairy cattle in China during 2010–2019: A systematic review and meta-analysis

BackgroundBovine tuberculosis (bTB), caused by members of the Mycobacterium tuberculosis complex bacteria, mainly Mycobacterium bovis (M. bovis), is a major threat to public health and economic development. There has been no systematic epidemiological assessment concerning bTB in dairy cattle in China.Methodology/principal findingsLiterature related to bTB in China was retrieved from China National Knowledge Infrastructure (CNKI), PubMed, ScienceDirect, VIP Chinese Journals Database, and Wan Fang Database to build the first meta-analysis for estimating the prevalence and infection moderators of bTB in dairy cattle in China. A total of 100 relevant studies published from 2010 to 2019 were included. We estimated the overall prevalence of bTB was 2.4% (95% CI: 2.1–2.8) during this decade. In the sampling year subgroup, the prevalence was lowest in 2017 or later at 0.8% (95% CI: 0.3–1.5). The lowest prevalence was 0.7% (95% CI: 0.5–1.0) in Northwestern China. The lowest prevalence was 2.1% (95% CI: 1.8–2.5) using SIT test. Heifer cows had the highest prevalence, which was 27.1% (95% CI: 9.7–49.2). The prevalence in scale farming was 3.7% (95% CI: 3.1–4.3), significantly higher than that in free-range farming (1.7%, 95% CI: 1.1–2.4). The prevalence of bTB was highest in summer at 4.0% (95% CI: 1.7–7.0). In addition, the influence of different geographical factors (altitude, longitude, latitude, precipitation, temperature, humidity) on the prevalence was analyzed.Conclusions/significanceThe results showed that bTB was widespread in China but has been gradually reduced through concerted national intervention. It is suggested that different countries should formulate corresponding prevention and control measures according to the epidemic situation in its cattle industry. Enhanced monitoring of warm and humid areas may play an important role in reducing the incidence of bTB. In addition, when large-scale breeding is promoted, attention should be paid to standardizing breeding management and improving animal welfare to reduce the prevalence of bTB in cattle.     

食品中细菌L型的研究

该文对食品中的细菌L型进行了初步研究,结果表明我国进出口食品中存在细菌L型的污染,而如果按常规培养法进行检测,就会导致漏检。因此开展食品中细菌L型的检验,一方面可提高阳性样品检出率,另一方面对提高食品卫生质量,保障人体健康有着重要意义。