Identifying the stability of housekeeping genes to be used for the quantitative real-time PCR normalization in retinal tissue of streptozotocin-induced diabetic rats

AIM:To investigate the stability of the seven housekeeping genes:beta-actin(ActB),glyceraldehyde-3-phosphate dehydrogenase(GAPDH),18s ribosomal unit 5(18s),cyclophilin A(CycA),hypoxanthine-guanine phosphoribosyl transferase(HPRT),ribosomal protein large P0(36B4)and terminal uridylyl transferase 1(U6)in the diabetic retinal tissue of rat model.METHODS:The expression of these seven genes in rat retinal tissues was determined using real-time quantitative reverse transcription polymerase chain reaction(RT-qPCR)in two groups;normal control rats and streptozotocininduced diabetic rats.The stability analysis of gene expression was investigated using geNorm,NormFinder,BestKeeper,and comparative delta-Ct(ΔCt)algorithms.RESULTS:The 36B4 gene was stably expressed in the retinal tissues of normal control animals;however,it was less stable in diabetic retinas.The 18s gene was expressed consistently in both normal control and diabetic rats’retinal tissue.That this gene was the best reference for data normalisation in RT-qPCR studies that used the retinal tissue of streptozotocin-induced diabetic rats.Furthermore,there was no ideal gene stably expressed for use in all experimental settings.CONCLUSION:Identifying relevant genes is a need for achieving RT-qPCR validity and reliability and must be appropriately achieved based on a specific experimental setting.

RPLP0/TBP are the most stable reference genes for human dental pulp stem cells under osteogenic differentiation

BACKGROUND Validation of the reference gene(RG)stability during experimental analyses is essential for correct quantitative real-time polymerase chain reaction(RT-qPCR)data normalisation.Commonly,in an unreliable way,several studies use genes involved in essential cellular functions[glyceraldehyde-3-phosphate dehydro-genase(GAPDH),18S rRNA,andβ-actin]without paying attention to whether they are suitable for such experimental conditions or the reason for choosing such genes.Furthermore,such studies use only one gene when Minimum Information for Publication of Quantitative Real-Time PCR Experiments guidelines recom-mend two or more genes.It impacts the credibility of these studies and causes dis-tortions in the gene expression findings.For tissue engineering,the accuracy of gene expression drives the best experimental or therapeutical approaches.We cultivated DPSCs under two conditions:Undifferentiated and osteogenic dif-ferentiation,both for 35 d.We evaluated the gene expression of 10 candidates for RGs[ribosomal protein,large,P0(RPLP0),TATA-binding protein(TBP),GAPDH,actin beta(ACTB),tubulin(TUB),aminolevulinic acid synthase 1(ALAS1),tyro-sine 3-monooxygenase/tryptophan 5-monooxygenase activation protein,zeta(YWHAZ),eukaryotic translational elongation factor 1 alpha(EF1a),succinate dehydrogenase complex,subunit A,flavoprotein(SDHA),and beta-2-micro-globulin(B2M)]every 7 d(1,7,14,21,28,and 35 d)by RT-qPCR.The data were analysed by the four main algorithms,ΔCt method,geNorm,NormFinder,and BestKeeper and ranked by the RefFinder method.We subdivided the samples into eight subgroups.RESULTS All of the data sets from clonogenic and osteogenic samples were analysed using the RefFinder algorithm.The final ranking showed RPLP0/TBP as the two most stable RGs and TUB/B2M as the two least stable RGs.Either theΔCt method or NormFinder analysis showed TBP/RPLP0 as the two most stable genes.However,geNorm analysis showed RPLP0/EF1αin the first place.These algorithms’two least stable RGs were B2M/GAPDH.For BestKeeper,ALAS1 was ranked as the most stable RG,and SDHA as the least stable RG.The pair RPLP0/TBP was detected in most subgroups as the most stable RGs,following the RefFinfer ranking.CONCLUSION For the first time,we show that RPLP0/TBP are the most stable RGs,whereas TUB/B2M are unstable RGs for long-term osteogenic differentiation of human DPSCs in traditional monolayers.

Exploring valid internal-control genes in Porphyra yezoensis(Bangiaceae) during stress response conditions

To screen the stable expression genes related to the stress （strong light, dehydration and temperature shock） we applied Absolute real-time PCR technology to determine the transcription numbers of the selected test genes in Porphyra yezoensis, which has been regarded as a potential model species responding the stress conditions in the intertidal. Absolute real-time PCR technology was applied to determine the transcription numbers of the selected test genes in Porphyra yezoensis, which has been regarded as a potential model species in stress responding. According to the results of photosynthesis parameters, we observed that Y（II） and Fv/Fm were significantly affected when stress was imposed on the thalli of Porphyra yezoensis, but underwent almost completely recovered under normal conditions, which were collected for the following experiments. Then three samples, which were treated with different grade stresses combined with salinity, irradiation and temperature, were collected. The transcription numbers of seven constitutive expression genes in above samples were determined after RNA extraction and cDNA synthesis. Finally, a general insight into the selection of internal control genes during stress response was obtained. We found that there were no obvious effects in terms of salinity stress （at salinity 90） on transcription of most genes used in the study. The 18S ribosomal RNA gene had the highest expression level, varying remarkably among different tested groups. RPS8 expression showed a high irregular variance between samples. GAPDH presented comparatively stable expression and could thus be selected as the internal control. EF-la showed stable expression during the series of multiple-stress tests. Our research provided available references for the selection of internal control genes for transcripts determination of P. yezoensis.

Validation of Reference Genes for Quantitative Real-Time PCR in Laodelphax striatellus

The normalization of quantitative real-time PCR （qPCR） is important to obtain accurate gene expression data, and the most common method for qPCR normalization is to use reference genes. However, reference genes can be regulated under different conditions, qPCR has recently been used for gene expression study in Laodelphax striatellus, but there is no study on validation of the reference genes. In this study, five new housekeeping genes （LstrTUB1, LstrTUB2, LstrTUB3, LstrARF and LstrRPL9） in L. striatellus were cloned and deposited in the GenBank with accession numbers of JF728809, JF728810, JF728811, JF728807 and JF728806, respectively. Furthermore, mRNA expressions of the five genes and β-actin were measured by qPCR with insect samples of different instar at nymph stage, and the expression stabilities were determined by the software geNorm and NormFinder. As a result, ARF and RPL9 were consistently more stable than β-actin, while three TUB genes were less stable than β-actin. To determine the optimal number of reference genes used in qPCR, a pairwise variations analysis by geNorm indicated that two references ARF and RPL9 were required to obtain the accurate quantification. These results were fiarther confirmed by the validation qPCR experiment with chitinase gene as the target gene, in which the standard error of the mRNA quantification by using binary reference ARF-RPL9 was much lower than those by ARF, RPL9 or β-actin alone. Taken together, our study suggested that the combination of ARF-RPL9 could replace β-actin as the reference genes for qPCR in L. striatellus.

Assessment of internal controls for data normalization of gene expression after different bacterial stimulation by quantitative real-time PCR in golden pompano Trachinotus blochii

Trachinotus blochii is one of the important commercial fish species.In this study,we aim to confirm the reliability reference genes in T.blochii during different bacterial challenge through quantitative real-time PCR(qRT-PCR).The expression of the seven selected genes in four immune organs(i.e.,spleen,kidney,intestine,and gill)stimulated with Vibrio harveyi,Edwardsiella tarda,and Streptococcus agalactiae were determined by qRT-PCR.The PCR data was analyzed using the geNorm and NormFinder algorithms.The results showed the selection of the internal controls should be tissue specific when studying gene expression in response to bacterial stimulation.After 48 h of stimulation with V.harveyi,geNorm ranked EF1 A/Actin,18 S rRNA/B2M,UBCE/B2M,and 18 S rRNA/B2M,as the most stably expressed genes in spleen,kidney,intestine,and gill,respectively.After 48 h of stimulation with E.tarda,geNorm ranked 18 S rRNA/EF1 A,18 S rRNA/B2M,B2M/RPL13,and 18 S rRNA/EF1 A,as the most stably expressed genes in spleen,kidney,intestine,and gill,respectively.After 48 h of stimulation with S.agalactiae,18 S rRNA/EF1 A,18 S rRNA/B2 M,B2 M/Actin,and 18 S rRNA/B2M were ranked as the most stably expressed genes in spleen,kidney,intestine,and gill,respectively.Compared to the results analyzed by geNorm,reference genes received similar rankings when using NormFinder software.The results showed that the reference genes appeared to be not only tissue specific,but also specific to the infecting species of bacteria.If one gene is preferred when T.blochii were infected by bacteria,18 S rRNA,B2M,B2M,18 S rRNA may be used in spleen,kidney,intestine,and gill,respectively.

Identification of potential internal control genes for real-time PCR analysis during stress response in Pyropia haitanensis

Pyropia haitanensis has prominent stress-resistance characteristics and is endemic to China. Studies into the stress responses in these algae could provide valuable information on the stress-response mechanisms in the intertidal Rhodophyta. Here, the effects of salinity and light intensity on the quantum yield of photosystem II in Py. haitanensis were investigated using pulse-amplitude-modulation fluorometry. Total RNA and genomic DNA of the samples under different stress conditions were isolated. By normalizing to the genomic DNA quantity, the RNA content in each sample was evaluated. The cDNA was synthesized and the expression levels of seven potential internal control genes were evaluated using qRT-PCR method. Then, we used geNorm, a common statistical algorithm, to analyze the qRT-PCR data of seven reference genes. Potential genes that may constantly be expressed under different conditions were selected, and these genes showed stable expression levels in samples under a salinity treatment, while tubulin, glyceraldehyde- 3-phosphate dehydrogenase and actin showed stability in samples stressed by strong light. Based on the results of the pulse amplitude-modulation fluorometry, an absolute quantification was performed to obtain gene copy numbers in certain stress-treated samples. The stably expressed genes as determined by the absolute quantification in certain samples conformed to the results of the geNorm screening. Based on the results of the software analysis and absolute quantification, we proposed that elongation factor 3 and 18S ribosomal RNA could be used as internal control genes when the Py. haitanensis blades were subjected to salinity stress, and that a-tubulin and 18S ribosomal RNA could be used as the internal control genes when the stress was from strong light. In general, our findings provide a convenient reference for the selection of internal control genes when designing experiments related to stress responses in Py. haitanensis.

Identification of normalization factors for quantitative realtime RT-PCR analysis of gene expression in Pacific abalone Haliotis discus hannai

Quantitative real-time reverse transcription-polymerase chain reaction （qRT-PCR） is widely used in studies of gene expression. In most of these studies, housekeeping genes are used as internal references without validation. To identify appropriate reference genes for qRT-PCR in Pacific abalone Haliotis discus hannai, we examined the transcription stability of six housekeeping genes in abalone tissues in the presence and absence of bacterial infection. For this purpose, abalone were infected with the bacterial pathogen Fibrio anguillarum for 12 h and 48 h. The mRNA levels of the housekeeping genes in five tissues （digestive glands, foot muscle, gill, hemocyte, and mantle） were determined by qRT-PCR. The PCR data was subsequently analyzed with the geNorm and NormFinder algorithms. The results show that in the absence of bacterial infection, elongation factor-l-alpha and beta-actin were the most stably expressed genes in all tissues, and thus are suitable as cross-tissue type normalization factors. However, we did not identify any universal reference genes post infection because the most stable genes varied between tissue types. Furthermore, for most tissues, the optimal reference genes identified by both algorithms at 12 h and 48 h post-infection differed. These results indicate that bacterial infection induced significant changes in the expression of abalone housekeeping genes in a manner that is dependent on tissue type and duration of infection. As a result, different normalization factors must be used for different tissues at different infection points.

MLST analysis of genetic diversity of Bacillus coagulans strains to evaluate effects on constipation model

Bacillus coagulans can help ameliorate or prevent gastrointestinal diseases, but the genetic relationships among B. coagulans isolates are not well studied. Multilocus sequence typing analysis was conducted on 57 isolates of B. coagulans from 22 provinces or autonomous regions in China. B. coagulans isolates were highly diverse and a total of 33(sequence typings) STs were found. These isolates had a weak clonal population structure and strong indications of intraspecies recombination. The evolution direction of B. coagulans was not correlated with geography or isolation source. Fifteen strains were selected for further analysis based on proximity relationships from the phylogenetic tree. Five isolates(B. coagulans-1, B. coagulans-10, B. coagulans-39, B. coagulans-70 and B. coagulans-71) with good spore-forming ability relative to the rest of the isolates were evaluated for constipation relief. B. coagulans-39 significantly relieved constipation symptoms in mice by regulating intestinal flora, increasing the production of short-chain fatty acids and restoring the level of gastrointestinal regulatory peptides. Comparative genomic analysis showed the beneficial effects of B. coagulans-39 might be associated with specific functional genes that are involved in the utilization of various carbohydrates as primary substrates and short-chain fatty acid production.

Validation of Reference Genes for mRNA Quantification in Adjuvant Arthritis

Real time quantitative PCR (RT-qPCR) requires a method to normalize the expression of target genes against an en- dogenous reference gene. It is known that commonly used housekeeping genes (HKGs) vary tremendously in inflam- matory conditions;however information about the stability and expression of HKGs in chronic inflammatory joint dis- ease such as rheumatoid arthritis (RA) is scarce. The expressional stability of 10 commonly used HKGs was analyzed in the neuronal (spinal cord, dorsal root ganglia) and in the musculoskeletal tissues (tendon, muscle, epiphysis, capsule, periosteum and ankle joint) using RT-qPCR in the rat model of RA. In individual tissues, suitable HKGs were selected by | △Ct| (│Ct control-Ct arthritis│) and further analyzed by using software programs;geNorm and normfinder. We found hypoxanthine-guanine phosphoribosyl tranferase (HPRT) as the most stable gene except ankle joint while glyce-raldehyde-3-phosphate dehydrogenase (GAPDH) was found as the least stable gene in musculoskeletal tissues. In in-flamed ankle joint where no reference gene was found to be stably expressed, an inflammatory cell marker CD3 was used to normalize peptidylprolyl isomerase B (PPIB), the most homogenous HKG identified among the 10 HKGs. The normalized PPIB was then used to analyze the gene expression of neurokinin 1 (NK1), receptor of substance P, a potent pro-inflammatory mediator. We observed a 3.5 fold increase (p = 0.009) in NK1 expression in inflamed ankle joint compared to control. Our results indicate that reference genes stability should be evaluated before using them as refer- ence during inflammatory conditions. In tissues with intense inflammatory cell infiltration, an inflammatory cell marker should be used to normalize the selected reference gene to avoid erroneous results.

进口蜂蜜中幼虫芽孢杆菌分子分型方法的比较研究

为研究来自不同地域幼虫芽孢杆菌的进化关系,建立其分子分型方法,对来自11个国家和地区的50株幼虫芽孢杆菌分离株进行MLST分型分析,并与ERIC分型比较。结果显示,ERIC法将50株分离株分为ERICⅠ、ERICⅡ与ERICⅣ型,但不能区分不同区域菌株;MLST法将菌株分为ST1至ST8共8种序列型,其中ST1为优势型,占比高且分布广泛;其次为ST5(主要为加拿大分离株),ST3(澳大利亚分离株),ST4(法国与匈牙利分离株),ST6(新西兰分离株),ST2(西班牙分离株),ST7(匈牙利分离株)和ST8(澳大利亚分离株)。与ERIC相比,MLST可以对不同地域的幼虫芽孢杆菌进行有效分型,具有更高的分辨率,可作为后续进口蜂蜜中幼虫芽孢杆菌流行病学调查的工具。

Identification of Rhizobia Isolated from Nodules of Mexican Commercial Soybean Varieties

Rhizobia, crucial for nitrogen fixation in leguminous plants, play a vital role in soybean cultivation. This study, conducted in Mexico, a major soybean importer, aimed to identify bacteria from nodules of five soybean varieties in high-production regions. Multilocus sequence analysis (MLSA) was employed for enhanced species resolution. The study identified six Bradyrhizobium species: Bradyrhizobium japonicum USDA 110, Bradyrhizobium japonicum USDA 6, Bradyrhizobium elkanii USDA 76, Bradyrhizobium neotropicale, Bradyrhizobium lablabi, and Bradyrhizobium icense. Bradyrhizobium japonicum USDA 110 predominated in the soils, displaying symbiotic preference for the Huasteca 400 variety. However, phylogenetic analysis didn't reveal a clear association between strains, soil, and soybean variety. This research sheds light on the diversity of rhizobia in Mexican soybean cultivation, contributing to the understanding of symbiotic relationships in soybean production systems.

狐狸源致病性维氏气单胞菌的分离鉴定及耐药性分析

本研究通过生物学特性、16S rRNA基因和4种等看家基因的序列测定与分析,对分离自北京动物园死亡狐狸病变组织的1株细菌进行鉴定,并对其进行小鼠致病力试验及药物敏感性试验。结果显示:该细菌为革兰氏阴性杆菌,培养特性、理化反应与维氏气单胞菌温和生物型基本相同;根据16S rRNA基因和dnaJ、rpoD、gyrB、cpn60等看家基因的系统进化及其同源性分析,确定所分离的细菌与维氏气单胞菌属于同一系统发育分支,各基因同源性最高分别为97.6%～99.9%。分离菌株对CD-1小鼠有较强的致病作用,其半数致死量为2.8×105cfu/只;对氧氟沙星、头孢他啶等14种抗菌药物敏感,对青霉素G、克林霉素等9种抗菌药物耐药。

鸡源鲍氏志贺菌hn03株的分子鉴定与演化分析

以鸡源鲍氏志贺菌为研究对象,根据GenBank中收录的相应序列针对8个看家基因thrB/thrC、trpC/tr-pB、purM/purN、mdh/argR设计相应引物,分别扩增出8个目的基因,然后克隆到pMD18-T vector,进一步测定序列,并将序列测定结果登陆GenBank。利用BLAST和ClustalX程序分析测序结果,构建了8个看家基因在染色体上4个区域的相应遗传进化树。由构建的系统进化树可知:志贺菌分为3个主要分支,且均落在大肠杆菌中,本研究中的分离菌株鸡源鲍氏志贺菌在染色体上4个区域的进化树中分布位置一致,均落在志贺菌3个主要分支中的第一分支;从整个基因水平上看,鸡源鲍氏志贺分离株应起源于人源志贺菌。

拟诺卡氏菌16S rRNA,gyrB,sod和rpoB基因的系统发育分析

为了更好地了解拟诺卡氏菌属(Nocardiopsis)各物种间的系统发育关系,该属现有有效描述种的gyrB,sod和rpoB基因的部分序列被测定,结合16S rRNA基因,对拟诺卡氏菌属进行了系统发育重建。研究发现拟诺卡氏菌属gyrB,sod和rpoB基因的平均相似性分别为87.7%、87.3%和94.1%,而16S rRNA基因的平均相似性则达到96.65%,3个看家基因均比16S rRNA具有更高的分歧度。比较基于不同基因的系统树发现,由gyrB基因得到的系统树拓扑结构与16S rRNA得到的结构在亚群上基本一致。因此,gyrB基因在拟诺卡氏菌属的系统分类上比16S rRNA基因更具优越性。

鸡杆菌河南分离株的分子进化分析

【目的】确定鸡杆菌河南分离株的具体种属和进化地位。【方法】以9株鸡杆菌河南分离株为研究对象,根据GenBank上登录的相关序列,针对鸡杆菌3个管家基因rpoB、infB和atpD设计引物,并进行PCR扩增、克隆和序列测定分析;将9株鸡杆菌的3个管家基因部分核苷酸序列,与已知的鸡杆菌属和巴氏杆菌科其他属相关参考株的相应基因序列进行比较分析并构建进化树。【结果】扩增出rpoBi、nfB和atpD3个管家基因部分序列,长度分别为566,531和1 441 bp,将测序结果登陆到GenBank。鸡杆菌分离株间的同源性分别为98.3%~100%（rpoB）、90.5%~100%（infB）和98.3%~100%（atpD）;分离株与国外鸭源鸡杆菌分离株间的同源性分别为97.1%~98.5%（rpoB）8、5.2%~93.2%（infB）和98.3%~98.8%（atpD）;分离株与国外鸡杆菌属其他种的同源性分别为84.3%~86.8%（rpoB）,83.1%~86.7%（infB）;鸡杆菌分离株与巴氏杆菌科其他代表属的同源性分别为77.4%~79.3%（rpoB）、78.2%~79.7%（infB）和83.5%~84.1%（atpD）。遗传进化分析显示,9株鸡杆菌河南分离株与鸭源鸡杆菌处于同一大分支之中。【结论】9株鸡杆菌河南分离株均为鸭源鸡杆菌。

四川部分地区禽源空肠弯曲菌MLST分型及遗传进化分析

目的为了解四川部分地区分离到的48株禽源空肠弯曲菌间的分子特征,以对来源不同的空肠弯曲菌进行分子分型及遗传进化分析。方法本研究参照MLST数据库,选取了空肠弯曲菌MLST分型7个管家基因aspA,glnA,glyA,gltA,tkt,pgm和uncA作为目的基因分别扩增及测序,并将所得序列经比对后进行遗传进化分析。结果 48株分离株中共含24种不同的序列型分属于9种不同的克隆系及11种独特型,其中22株分离株含有新序列型,占分离株的45.83%(22/48);9种不同的克隆系中以CC-21、CC-353、CC-464克隆系所含菌株相对较多,而克隆系CC-45、CC-48最少,均为1株分离株;11种独特型共存于21株分离株中,其中以ST-8675序列型最多,为8株。遗传进化树显示,属同一克隆系的不同型别间的分离株亲缘关系较近,如同属于CC-21克隆系的ST-298与ST-760型别分离株处于同一小分支、亲缘关系较近,但不同克隆系的分离株间遗传进化关系较远,鹌鹑源分离株(V13-20)单独处于一大分支与其余禽源分离株间的亲缘关系最远。总体而言,不同地区、宿主来源的分离株呈现遗传多样性。结论本研究中分离株间具有基因多样性,MLST分型为了解该地区空肠弯曲菌的遗传特性和分布特点提供了参考依据。

霍乱弧菌主要毒力和管家基因序列分析

目的分析广东霍乱弧菌（VC）代表菌株主要毒力基因和管家基因序列。方法PCR扩增霍乱弧菌的主要毒力基因（ctxAB和tcpA）和管家基因（dnaE、hlyA、mdh和recA）、基因测序、对序列进行生物信息学分析。结果不同年代分离的2株埃尔托型（EVC）产毒株和1株0139群VC产毒株的主要毒力基因序列与国内外相关报告比较，ctxA基因及推测的氨基酸序列的同源性分别为99．7％～100％和98．8％～100％．ctxB基因及推测的氨基酸序列的同源性分别为98．8％～100％和96．8％～100％，tcpA基因序列与EVC国际标准株N16961 100％同源。3株产毒株的dnaE、hlyA、mdh和recA基因序列同源性分别为99．8％～100％，100％，99．5％～99．8％和100％，氨基酸序列同源性分别为100％．100％，98．5％～99．3％和100％；3株产毒株和O139群VC非产毒株的管家基因序列同源性分别为97．0％～97．2％，91．8％，94．1％～94．4％，96．9％，氨基酸序列同源性分别为100％，94．6％，94．3％～98．5％和99．7％。结论广东省不同年代EVC产毒株和O139群VC产毒株的群体遗传学关系高度密切，而与O139群VC非产毒株较远，O139群VC产毒株可能起源于EVC产毒株。

实时RT-PCR检测大鼠死后管家基因mRNA的时序性降解

目的研究实时荧光定量RT-PCR方法检测死亡大鼠管家基因mRNA时序性降解的可行性,为死亡时间(postmortem interval,PMI)推断寻找新的研究手段。方法应用SYBR GreenⅠ实时荧光定量RT-PCR技术,检测死后不同时间大鼠脑和脾中管家基因GAPDH mRNA及β-actin mRNA的水平,结果用循环阈值(简称Ct值)表示,分析死后经过时间与Ct值的线性关系,并建立死亡时间推断回归方程。结果GAPDH mRNA和β-actin mRNA的Ct值均与PMI之间存在显著的相关性。结论SYBR GreenⅠ实时荧光定量RT-PCR在定量分析mRNA降解的研究中是一个较理想的技术手段。选用管家基因作为PMI推断的研究对象,可在法医检案中消除其他基因因为个体差异带来的误差,更具实用性。Ct值作为动态监测机体死后不同时间点的客观指标,与死后不同时间点的线性关系良好,推断死后经过时间尤其是晚期死亡时间较为理想。

不同群型霍乱弧菌recA、dnaE和mdh管家基因序列分析

目的不同群型霍乱弧菌(VC)recA、dnaE和mdh管家基因序列分析。方法PCR扩增、基因测序及生物信息学分析。结果18株不同群型霍乱弧菌recA基因500bp序列中共44个位点发生变异,只有3个位点变异导致氨基酸变异;dnaE基因600bp序列中共32个位点发生变异,只有1个位点变异导致氨基酸变异;mdh基因367bp序列中共21个位点发生变异,只有1个位点变异导致氨基酸变异。O1群埃尔托生物型(EVC)产毒株和O139群VC产毒株遗传学关系高度密切;不同群型非产毒株之间遗传学关系较远;不同群型产毒株和不同群型非产毒株遗传学关系较远。结论我国不同地区流行的EVC产毒株和O139群VC产毒株可能分别来自同一克隆群,O139群VC产毒株可能起源于EVC产毒株。

上海市动物源性食品中单增李斯特菌的MLST分析

为了解上海市动物性食品中单增李斯特菌的进化情况和群体遗传学特征,本研究采用MLST法和eBURST软件对33株分离株进行分子分型及进化树分析。结果共分成8个型别,并且33株单增李斯特菌之间遗传相关性不是很大。分为4个进化谱系:ST11和ST196为一个进化谱系,ST9、ST8和ST155为一个进化谱系,ST87和ST277/589为一个进化谱系,所占比例最多的ST121单独一个进化谱系。