不同产地忽地笑的叶绿体基因psb A-trn H序列分析

目的通过叶绿体基因psb A-trn H序列分析,探讨我国忽地笑种质资源的系统进化关系及分子鉴定方法。方法分别提取15省(市)52个忽地笑居群的DNA,经PCR扩增叶绿体基因psb A-trn H序列及测序,并用Mega5.0等软件对测序结果进行分析。结果 52条psb A-trn H序列长度为544～656 bp,GC含量为35.8%～37.0%,遗传距离为0.000 00～0.009 47;核苷酸变异(多态性)位点数共33个,其中简约信息位点9个,单一突变位点18个,插入/缺失片段6个;单倍型数量(H)10个,单倍型多态性水平(Hd)0.749,核苷酸多态性(π)0.002 63,收集的忽地笑资源具有较高的遗传多样性。最大简约法(maximum parsimony,MP)系统树中52个居群聚为4类,并且该聚类结果与其地理分布基本一致。结论不同产地忽地笑居群的遗传变异较大,psb A-trn H序列可作为忽地笑种源分子鉴定的依据;我国忽地笑种质资源在进化上具有明显的地域性特征。     

基于ISSR的连翘遗传多样性研究

目的研究不同居群连翘的遗传多样性。方法采用ISSR分子标记技术对连翘25个自然居群的样本进行分析,利用POPGENE32软件分析多态位点百分率(P)、Nei’s基因多样性指数(H)及Shannon多样性指数(I);居群间遗传一致度采用NTSYSpc-2.10软件进行聚类分析。结果选出13条ISSR引物,扩增出353条清晰条带,物种水平P为100%,H为0.252 3,I为0.394 0,遗传分化系数(Gst)为0.331 8,居群间基因流(Nm)为1.007 0,遗传距离0.031 0～0.155 5;NTSYSpc软件进行系统聚类,将25个聚群划分为2大类,7分组;连翘个体间进行聚类分析,195份连翘样品划分为2大类,5分组。结论连翘种群遗传多样性水平较高,但连翘种群间遗传距离与地理距离没有相关性,与生态因子和生长环境有关。     

Genetic Diversity,Antibiotic Resistance,and Pathogenicity of Aeromonas Species from Food Products in Shanghai,China

ObjectiveAeromonas has recently been recognized as an emerging human pathogen. Aeromonas-associated diarrhea is a phenomenon occurring worldwide. This study was designed to determine the prevalence, genetic diversity, antibiotic resistance, and pathogenicity of Aeromonas strains isolated from food products in Shanghai.MethodsAeromonas isolates (n = 79) collected from food samples were analyzed using concatenated gyrB-cpn60 sequencing. The antibiotic resistance of these isolates was determined using antimicrobial susceptibility testing. Pathogenicity was assessed using β-hemolytic, extracellular protease, virulence gene detection, C. elegans liquid toxicity (LT), and cytotoxicity assays.ResultsEight different species were identified among the 79 isolates. The most prevalent Aeromonas species were A. veronii [62 (78.5%)], A. caviae [6 (7.6%)], A. dhakensis [3 (3.8%)], and A. salmonicida [3 (3.8%)]. The Aeromonas isolates were divided into 73 sequence types (STs), of which 65 were novel. The isolates were hemolytic (45.6%) and protease-positive (81.0%). The most prevalent virulence genes were act (73.4%), fla (69.6%), aexT (36.7%), and ascV (30.4%). The results of C. elegans LT and cytotoxicity assays revealed that A. dhakensis and A. hydrophila were more virulent than A. veronii, A. caviae, and A. bivalvium. Antibiotic resistance genes [tetE, blaTEM, tetA, qnrS, aac(6)-Ib, mcr-1, and mcr-3] were detected in the isolates. The multidrug-resistance rate of the Aeromonas isolates was 11.4%, and 93.7% of the Aeromonas isolates were resistant to cefazolin.ConclusionThe taxonomy, antibiotic resistance, and pathogenicity of different Aeromonas species varied. The Aeromonas isolates A. dhakensis and A. hydrophila were highly pathogenic, indicating that food-derived Aeromonas isolates are potential risks for public health and food safety. The monitoring of food quality and safety will result in better prevention and treatment strategies to control diarrhea illnesses in China.     

Consumption of highly processed snacks,sugar‐sweetened beverages and child feeding practices in a rural area of Nicaragua

Appropriate feeding behaviours are important for child growth and development. In societies undergoing nutrition transition, new food items are introduced that may be unfavourable for child health. Set in rural Nicaragua, the aim of this study was to describe the infant and young child feeding (IYCF) practices as well as the consumption of highly processed snack foods (HP snacks) and sugar‐sweetened beverages (SSBs). All households with at least one child 0‐ to 35‐month‐old (n = 1371) were visited to collect information on current IYCF practices in the youngest child as well as consumption of SSBs and HP snacks. Breastfeeding was dominant (98%) among 0‐ to 1‐month‐olds and continued to be prevalent (60%) in the second year, while only 34% of the 0‐ to 5‐month‐olds were exclusively breastfed. Complementary feeding practices were deemed acceptable for only 59% of the 6‐ to 11‐month‐old infants, with low dietary diversity reported for 50% and inadequate meal frequency reported for 30%. Consumption of HP snacks and SSBs was frequent and started early; among 6‐ to 8‐month‐olds, 42% and 32% had consumed HP snacks and SSBs, respectively. The difference between the observed IYCF behaviours and World Health Organization recommendations raises concern of increased risk of infections and insufficient intake of micronutrients that may impair linear growth. The concurrent high consumption of SSBs and HP snacks may increase the risk of displacing the recommended feeding behaviours. To promote immediate and long‐term health, growth and development, there is a need to both promote recommended IYCF practices as well as discourage unfavourable feeding behaviours.     

Extensive cross-reactive neutralizing antibody response in Indian patients with limited genetic diversity of HIV-1

Genome sequence analysis of HIV-1 subtype C viruses from India shows monophyletic lineage and relatively limited genetic diversity. To understand its immunological implication, cross-reactivity of neutralizing antibody response was investigated. In primary screening, neutralizing antibody response to single heterologous primary HIV-1 subtype C isolate was assessed in plasma samples from 235 HIV-1 infected, anti-retroviral treatment naive individuals from Pune, India. Plasma samples that showed > or =90% neutralization and two randomly selected plasma samples that showed 50-60% neutralization were tested against a panel of primary HIV-1 subtype C isolates obtained from epidemiologically unlinked individuals from India. The neutralizing antibody response showed extensive cross-neutralization, suggesting presence of shared neutralization determinants among circulating HIV-1 subtype C viruses in India.     

Clonotypic analysis of T cell reconstitution after haematopoietic stem cell transplantation (HSCT) in patients with severe combined immunodeficiency

Haematopoietic stem cell transplantation (HSCT) is performed for treatment of a broad spectrum of illnesses. Reconstitution of an intact immune system is crucial after transplantation to avoid infectious complications, and above all, the establishment of T cell receptor (TCR) diversity is the most important goal in the procedure. Until recently, little has been known of the mechanism of T cell reconstitution in the very early period after HSCT. In this study, we analysed TCR repertoires sequentially in four patients with severe combined immunodeficiency (SCID) before and after HSCT. In all patients, the TCR repertoires were extremely abnormal before HSCT, whereas after transplantation there was progressive improvement in TCR diversity, based on analysis of the TCR Vbeta repertoire and CDR3 size distributions. Somewhat unexpectedly, there was a significant but transient expansion of TCR diversity 1 month after transplantation in all cases. Clonotypic analysis of TCRs performed in one case showed that many T cell clones shared identical CDR3 sequences at 1 month and that the shared fraction decreased progressively. These results indicate that early expansion of TCR diversity may reflect transient expansion of pre-existing mature T cells from the donor blood, independent of de novo T cell maturation through the thymus.     

Seasonal variation in the association between household food insecurity and child undernutrition in Bangladesh: Mediating role of child dietary diversity

Household food insecurity (HFI) and child dietary diversity (CDD) are variable across seasons. We examined seasonal variation in HFI and child undernutrition association and tested how CDD mediates this association. We analyzed data for 26,353 children aged 6–59 months drawn from nationally representative cross-sectional Food Security and Nutrition Surveillance Project data collected during 2012–2014 in Bangladesh across three seasons annually: Post-Aman harvest (January–April); Monsoon (May–August); and Post-Aus harvest (September–December). Multivariable logistic regression analysis adjusted for individual, maternal, household and geographical characteristics reveals that children of food-insecure households were more likely than food-secure households to be stunted (adjusted odds ratio, AOR: 1.12; 95% confidence interval, CI: 1.02–1.23; p < 0.05), wasted (AOR: 1.21; 95% CI: 1.05–1.39; p < 0.01) and underweight (AOR: 1.16; 95% CI: 1.04–1.3; p < 0.01). CDD mediated 6.1% of the total effect of HFI on underweight. These findings varied across seasons. HFI was associated with greater odds of underweight during Monsoon (AOR: 1.32; 95% CI: 1.08–1.62; p < 0.01) and Post-Aus (AOR: 1.21; 95% CI: 1.06–1.37; p < 0.01) while wasting during Post-Aus (AOR: 1.65; 95% CI: 1.35–2.01; p < 0.001). CDD largely mediated the total effect of HFI on underweight during the Post-Aman in 2012–2014 (23.2%). CDD largely mediated the total effect of HFI on wasting (39.7%) during Post-Aman season in 2014 and on underweight (13.7%) during the same season in 2012. These findings demonstrate that HFI is seasonally associated with child undernutrition and mediated by CDD as well in Bangladesh and seasonality and diversity should be considered while designing appropriate population-level food-based interventions to resolve child undernutrition.