生物多样性与传染性疾病的关系: 进展、挑战与展望

在全球生物多样性快速丧失的背景下, 理解生物多样性如何影响传染性疾病风险具有重要意义。大量研究表明, 宿主多样性对传染性疾病可能存在稀释效应(即疾病风险随宿主生物多样性的增加而降低), 但是也有放大效应或者没有影响的证据。本文首先介绍了关于生物多样性与传染性疾病关系的研究进展, 以及该领域的热点研究问题, 包括宿主多样性-疾病关系的格局和空间依赖性、稀释效应的体系依赖性和系统发育稀释效应等。随后,介绍了相关研究伴随的争议和批判, 主要集中在: 稀释效应发生的普遍性、生物多样性-疾病关系实验研究的发表偏好性以及部分疾病生态学家对生物多样性和传染性疾病之间简单数字关系的过分关注。最后指出稀释效应与物种共存、全球变化对稀释效应的影响、进化与稀释效应、稀释效应在政策制定中的应用等领域可能是今后的主要研究方向。     

肉类及肉制品中动物源性成分鉴别方法研究进展

肉类掺假问题直接影响着人类健康、公共卫生安全以及社会稳定等方面,成为当今食品安全热点话题之一,因此,高效、精确的肉类及肉制品中动物源性成分的检测鉴定势在必行。基于此,主要介绍了对于动物源性成分检测及鉴别的不同研究方法,分析了利弊,并对后续肉类及肉制品中动物源性成分的鉴别方法的研发方向进行了展望,以期为此领域提供资料性参考。     

Amplification of RAD54B promotes progression of hepatocellular carcinoma via activating the Wnt/β-catenin signaling

Liver cancer was reported to be the sixth most frequently diagnosed cancer, and hepatocellular carcinoma (HCC) accounts for 75%-85% of primary liver cancer. Nevertheless, the concrete molecular mechanisms of HCC progression remain obscure, which is essential to elucidate. The expression profile of RAD54B in HCC was measured using qPCR and western blotting. Moreover, the levels of RAD54B in paraffin-embedded samples were evaluated using immunohistochemistry (IHC). The effect of RAD54B on HCC progression was testified by in vitro experiments, and in vivo orthotopic xenograft tumor experiments. The mechanisms of RAD54B promoting HCC progression were investigated through molecular and function experiments. Herein, RAD54B are dramatically upregulated in HCC tissues and cell lines both on mRNA and protein levels, and RAD54B can servers as an independent prognostic parameter of 5-year overall survival and 5-year disease-free survival for patients with HCC. Moreover, up-regulation of RAD54B dramatically increases the capacity for in vitro cell viability and motility, and in vivo intrahepatic metastasis of HCC cells. Mechanistically, RAD54B promotes the HCC progression through modulating the wnt/β-catenin signaling. Notably, blocking the wnt/β-catenin signaling axis can counteract the activating effects of RAD54B on motility of HCC cells. Besides, further analysis illustrates that DNA amplification is one of the mechanisms leading to mRNA overexpression of RAD54B in HCC. Our findings indicate that RAD54B might be a promising potential prognostic marker and a candidate therapeutic target to therapy HCC.     

Application of an optimized marker amplification protocol in immunohistochemistry — a valuable tool for visualizing antigenic sites of low signal strength or sparse distribution

Amplification of immunohistochemical markers received considerable attention during the 1980s and 1990s. The amplification approach was largely abandoned following the development of antigen retrieval and reporter amplification techniques, because the latter were incorporated more easily into high throughput automated procedures in industrial and diagnostic laboratories. There remain, however, a number of instances where marker amplification still has much to offer. Consequently, we examined experimentally the utility of an optimized marker amplification technique in diagnostically relevant tissue where either the original signal strength was low or positive sites were visible, but sparsely distributed. Marker amplification in the former case not only improved the visibility of existing positive sites, but also revealed additional sites that previously were undetectable. In the latter case, positive sites were rendered more intense and therefore more easily seen during low magnification examination of large areas of tissue.     

Cubic regression-based degree of correction predicts the performance of whole bisulfitome amplified DNA methylation analysis

Epigenetic mechanisms, including DNA methylation, are important determinants in development and disease. There is a need for technologies capable of detecting small variations in methylation levels in an accurate and reproducible manner, even if only limited amounts of DNA are available (which is the case in many studies in humans). Quantitative methylation analysis of minute DNA amounts after whole bisulfitome amplification (qMAMBA) has been proposed as an alternative, but this technique has not been adequately standardized and no comparative study against conventional methods has been performed, that includes a wide range of methylation percentages and different target assays. We designed an experiment to compare the performance of qMAMBA and bisulfite-treated genomic (non-amplified) DNA pyrosequencing. Reactions were performed in duplicate for each technique in eight different target genes, using nine artificially constructed DNA samples with methylation levels ranging between 0% and 100% with intervals of 12.5%. Cubic polynomial curves were plotted from the experimental results and the real methylation values and the resulting equation was used to estimate new corrected data points. The use of the cubic regression-based correction benefits the accuracy and the power of discrimination in methylation studies. Additionally, dispersion of the new estimated data around a y = x line (R²) served to fix a cutoff that can discriminate, with a single 9-point curve experiment, whether whole bisulfitome amplification and subsequent qMAMBA can produce accurate methylation results. Finally, even with an optimized reagent kit, DNA samples subjected to whole bisulfitome amplification enhance the preferential amplification of unmethylated alleles, and subtle changes in methylation levels cannot be detected confidently.     

番茄褪绿病毒TaqMan荧光定量PCR快速检测方法的建立与应用

【目的】本研究旨在建立TaqMan实时荧光定量PCR(TaqMan RT-qPCR)技术,快速检测单头烟粉虱Bemisia tabaci体内的番茄褪绿病毒(tomato chlorosis virus,ToCV)。【方法】根据ToCV外壳蛋白保守序列设计了1对特异性引物和1条TaqMan探针,建立了TaqMan RT-qPCR方法;与常规PCR检测进行比较,检测该方法的灵敏度与特异性;并应用该方法对单头烟粉虱成虫体内ToCV进行了快速检测。【结果】本研究构建的TaqMan RT-qPCR检测ToCV的标准曲线,其循环阈值(Ct值)与模板浓度具有良好的线性关系,扩增效率为98%。该方法对ToCV的最低检测浓度为8.3×10 copies/μL,灵敏度是常规RT-PCR的1000倍。该方法与田间番茄两种重要病毒番茄黄化曲叶病毒(tomato yellow leaf curl virus,TYLCV)和番茄斑萎病毒(tomato spotted wilt virus,TSWV)检测无交叉反应。单头烟粉虱成虫ToCV检测结果表明,温室内ToCV侵染植株上烟粉虱携毒率为100%,田间烟粉虱的携毒率为30%。【结论】本研究建立的TaqMan RT-qPCR检测方法,可快速有效检测单头烟粉虱体内ToCV携毒情况,为该病毒病的防控提供了技术支撑。     

基于环介导等温扩增技术的微流控芯片在病原菌检测方面的研究进展

环介导等温扩增(LAMP)技术是一种新兴的核酸恒温扩增技术,与微流控芯片技术相结合,可实现对病原菌的快速检测,具有特异性强、灵敏度高、操作简单等优点。本文根据不同终产物的检测方法对目前检测病原菌的相关微流控LAMP芯片进行了分类与介绍,并对技术的改进和存在的问题进行了分析,以期为后续的相关研究提供参考。     

Isolation and characterization of RARE-1, a Ty1/copia-like retrotransposon domesticated in the genome of Rhizophora apiculata

Long terminal repeat (LTR) retrotransposons are predominant mobile elements that play important roles in plant genome evolution. Here, we isolated the first putative complete Ty1/copia-like retrotransposon of 6303 bp in mangrove Rhizophora apiculata, named RARE-1. RARE-1 was homologous to the soybean retroelement 1 (SORE-1) and exhibited abundant cis-regulatory motifs involved in various stress responses in its LTRs. Using the sequence-specific amplification polymorphism (S-SAP) technique, we obtained a total of 112 bands for two R. apiculata populations from Hainan, China and Ranong, Thailand. The Hainan population showed slightly higher S-SAP polymorphism but fewer unique bands than the Ranong population. Moreover, the Hainan population also had significantly more copies of RARE-1 than the Ranong population as revealed by quantitative real-time PCR (qPCR). Our results suggested that RARE-1 might have been domesticated in the R. apiculata genome, as a result of the long-term evolution of mangroves under the extreme environment.     

cDNA cloning,expression, and enzymatic activity of a novel endogenous cellulase from the beetle Batocera horsfieldi

In this study, we report a novel cellulase [β-1,4-endoglucanase (EGase), EC 3.2.1.4] cDNA (Bh-EGase II) belonging to the glycoside hydrolase family (GHF) 45 from the beetle Batocera horsfieldi. The Bh-EGase II gene spans 720 bp and consists of a single exon coding for 239 amino acid residues. Bh-EGase II showed 93.72% protein sequence identity to Ag-EGase II from the beetle Apriona germari. The GHF 45 catalytic site is conserved in Bh-EGase II. Bh-EGase II has three putative N-glycosylation sites at 56–58 (N–K–S), 99–101 (N–S–T), and 237–239 (N–Y–S), respectively. The cDNA encoding Bh-EGase II was expressed in baculovirus-infected insect BmN cells and Bombyx mori larvae. Recombinant Bh-EGase II from BmN cells and larval hemolymph had an enzymatic activity of approximately 928 U/mg. The enzymatic catalysis of recombinant Bh-EGase II showed the highest activity at 50 °C and pH 6.0.