Genetic background

遗传背景
  • 文章类型: Journal Article
    动脉粥样硬化性心血管疾病(ASCVD)是全球主要的死亡原因,个体筛查应该基于行为,新陈代谢,和从大型人群研究中收集的数据得出的遗传概况。由于ASCVD的多基因性质,我们旨在评估基因组学与ASCVD风险的关联及其对急性心肌梗死发生的影响,中风,或人群水平的外周动脉血栓性缺血事件。心血管基因(CV-GENES)是一个全国性的,多中心,1:1巴西3,734例患者的病例对照研究。病例的纳入标准是首次出现ASCVD事件之一。没有已知ASCVD的个人将有资格作为对照。核心实验室将通过低通全基因组测序和全外显子组测序进行遗传分析。为了估计遗传多态性与ASCVD之间的独立关联,多基因风险评分(PRS)将通过混合方法建立,包括每个单核苷酸多态性(SNP)的效应大小,观察到的效应等位基因数量,样本倍性,PRS中包含的SNP总数,和样品中未缺失的SNP的数量。此外,致病性或可能致病性变异的存在将在8个基因(ABCG5,ABCG8,APOB,APOE,LDLR,LDLRAP1,LIPA,PCSK9)与动脉粥样硬化有关。多元逻辑回归将用于估计调整后的优势比(OR)和95%置信区间(CI),并计算人口可归因风险。临床试验注册:本研究已在clinicaltrials.gov(NCT05515653)中注册。
    Atherosclerotic Cardiovascular Disease (ASCVD) represents the leading cause of death worldwide, and individual screening should be based on behavioral, metabolic, and genetic profile derived from data collected in large population-based studies. Due to the polygenic nature of ASCVD, we aimed to assess the association of genomics with ASCVD risk and its impact on the occurrence of acute myocardial infarction, stroke, or peripheral artery thrombotic-ischemic events at population level. CardioVascular Genes (CV-GENES) is a nationwide, multicenter, 1:1 case-control study of 3,734 patients in Brazil. Inclusion criterion for cases is the first occurrence of one of the ASCVD events. Individuals without known ASCVD will be eligible as controls. A core lab will perform the genetic analyses through low-pass whole genome sequencing and whole exome sequencing. In order to estimate the independent association between genetic polymorphisms and ASCVD, a polygenic risk score (PRS) will be built through a hybrid approach including effect size of each Single Nucleotide Polymorphism (SNP), number of effect alleles observed, sample ploidy, total number of SNPs included in the PRS, and number of non-missing SNPs in the sample. In addition, the presence of pathogenic or likely pathogenic variants will be screened in 8 genes (ABCG5, ABCG8, APOB, APOE, LDLR, LDLRAP1, LIPA, PCSK9) associated with atherosclerosis. Multiple logistic regression will be applied to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI), and population attributable risks will be calculated. Clinical trial registration: This study is registered in clinicaltrials.gov (NCT05515653).
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  • 文章类型: Journal Article
    先前的证据表明,儿童晒伤可能是皮肤恶性黑色素瘤(MM)和非黑色素瘤皮肤癌(NMSC)的危险因素。然而,现有的观察性研究无法揭示遗传上的因果关系。这项研究旨在调查儿童晒伤与皮肤癌之间是否存在遗传因果关系。单变量孟德尔随机化(MR)和因果分析使用总结效应分析进行因果估计和评价水平多效性。多变量MR和中介效应分析用于检验因果关系是否由潜在的混杂因素介导。儿童晒伤与MM之间存在明显的因果关系(OR=4.74;95%CI:1.31-17.19;p=1.79E-02)。遗传预测的儿童晒伤与整体原位黑色素瘤(MIS)的风险增加显着相关(OR=4.02;95%CI:2.00-8.08;p=9.40E-05),面部MIS(OR=18.28;95%CI:5.28-63.35;p=4.59E-06),和树干MIS(OR=7.05;95%CI:2.06-24.13;p=1.88E-03)。儿童晒伤和NMSC也发现了类似的趋势(OR=8.16;95%CI:6.07-10.99;p=1.53E-20),包括基底细胞癌(BCC)(OR=3.76;95%CI:2.96-4.77;p=2.19E-08)和鳞状细胞癌(SCC)(OR=7.44;95%CI:5.09-10.87;p=2.19E-08)。调整头发和皮肤颜色后,面部老化,维生素D水平,身体质量指数,酒精消费,和吸烟状况,童年晒伤表现出与MIS的独立关联,MIS的脸,后备箱的MIS,以及NMSC,包括BCC和SCC。中介分析显示无明显的中介效应。这项研究表明,儿童晒伤与MM和NMSC的风险之间存在因果关系。这表明加强筛查和预防儿童晒伤可能有助于早期发现和降低MM和NMSC的风险。
    Previous evidence has suggested that childhood sunburn could be a risk factor for cutaneous malignant melanoma (MM) and non-melanoma skin cancer (NMSC). However, existing observational studies could not reveal the causal associations genetically. This study aimed to investigate whether there was a genetic causal relationship between childhood sunburn and skin cancers. Univariable Mendelian randomization (MR) and Causal Analysis Using Summary Effect analysis was carried out for causal estimates and evaluation for the horizontal pleiotropy. Multivariable MR and the mediation effects analysis were used to test whether the causal associations were mediated by potential confounders. A suggestively significant causal association between childhood sunburn and MM was indicated (OR = 4.74; 95% CI: 1.31-17.19; p = 1.79E-02). Genetically predicted childhood sunburn was significantly associated with increased risk of overall melanoma in situ (MIS) (OR = 4.02; 95% CI: 2.00-8.08; p = 9.40E-05), MIS of face (OR = 18.28; 95% CI: 5.28-63.35; p = 4.59E-06), and MIS of trunk (OR = 7.05; 95% CI: 2.06-24.13; p = 1.88E-03). Similar trends were found for childhood sunburn and NMSC (OR = 8.16; 95% CI: 6.07-10.99; p = 1.53E-20), including both basal cell carcinoma (BCC) (OR = 3.76; 95% CI:2.96-4.77; p = 2.19E-08) and squamous cell carcinoma (SCC) (OR = 7.44; 95% CI: 5.09-10.87; p = 2.19E-08). After adjustment for hair and skin color, facial ageing, vitamin D levels, body mass index, alcohol consumption, and smoking status, childhood sunburn showed an independent association with MIS, MIS of face, MIS of trunk, as well as NMSC, including both BCC and SCC. Mediation analysis showed no significant mediation effect. This study demonstrated a causal relationship between childhood sunburn and the risk of both MM and NMSC, which suggested that enhanced screening and prevention for childhood sunburn could contribute to the early detection and decreased risk of MM and NMSC.
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  • 文章类型: Journal Article
    背景:大约0.5%的皮肤黑素瘤(CM)患者在首次发现时会出现同步性黑素瘤。此外,26-40%的多发性原发性黑色素瘤患者存在同步病变。
    目的:为了评估患病率,临床和组织病理学特征,同时性黑色素瘤患者的种系突变和预后。
    方法:纳入了4703例黑色素瘤患者的临床和组织病理学数据。临床,分析了组织学和基因突变状态信息。Kaplan-Meier曲线用于研究生存结果。
    结果:总共144例患者(3.06%)同时出现两个或两个以上的原发性黑素瘤。随访期间,25.7%的同步黑素瘤患者发展为新的原发性黑素瘤,而8.6%的患者诊断为单个黑素瘤(P<0.001)。在10.7%的同步黑素瘤患者中发现了生发CDKN2A突变,在72%的MC1R中发现了遗传变异。在同步性黑素瘤和单个黑素瘤患者之间,所有生存结果均未发现显着差异。
    结论:与单发黑素瘤相比,同步黑素瘤比以前报道的更常见,并且在老年患者中更常见。此外,这些患者在随访期间发生新的原发性黑色素瘤的风险较高,并且种系易感性变异的发生率较高.然而,这些发现与更差的结局无关.
    BACKGROUND: Around 0.5% of cutaneous melanoma (CM) patients will present with synchronous melanomas when first seen. Moreover, 26-40% of patients with multiple primary melanomas present with synchronous lesions.
    OBJECTIVE: To assess the prevalence, clinical and histopathological characteristics, germline mutations and outcome in patients with synchronous melanoma.
    METHODS: Clinical and histopathological data from 4703 melanoma patients were included. Clinical, histological and genetic mutational status information was analysed. Kaplan-Meier curves were used to investigate survival outcomes.
    RESULTS: A total of 144 patients (3.06%) presented simultaneously with two or more primary melanomas. During follow-up, 25.7% of patients with synchronous melanoma developed a new primary melanoma compared to 8.6% of patients diagnosed with single melanoma (P < 0.001). Germinal CDKN2A mutations were identified in 10.7% of patients with synchronous melanomas and genetic variants in MC1R in 72%. No significant differences in all survival outcomes between patients with synchronous melanomas and single melanomas were found.
    CONCLUSIONS: Synchronous melanomas are more frequent than previously reported and are more frequent in older patients compared to single melanomas. Moreover, these patients have a higher risk of developing a new primary melanoma during follow-up and have higher rates of germline susceptibility variants. Nevertheless, these findings were not associated with worse outcomes.
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  • 文章类型: Journal Article
    背景:使用遗传选择来获得更具弹性的农场动物(即受到干扰的影响最小或从它们中迅速恢复)的兴趣越来越大。本研究的目的是:(i)根据产蛋数据估计弹性指示性状的遗传参数,(ii)评估这些性状在纯种和杂种中是否具有遗传相关性,和(iii)评估这些性状与产卵(EP)的遗传相关性,作为25至83周之间的卵总数。纯种母鸡(来自WhiteLeghorn(WA)品系的33,825只和来自罗德岛(BD)品系的34,397只饲养在单独的笼子里,而杂交母鸡则被安置在6至8个父系半同胞的集体笼中(12,852WA和3898BD杂交组,其中组的名称是指用作父亲的行)。计算母鸡每周产蛋量与相应批次平均值的偏差。调查的弹性指示性状是方差的自然对数(LNVAR),偏斜度(SKEW),以及这些偏差的滞后一自相关(AUTO-R)。
    结果:在两条纯种路线中,EP被估计为低遗传性(WA:0.11和BD:0.12)。在这两条线中,弹性指标也被估计为低遗传性(LNVAR:0.10和0.12,SKEW:0.04和0.02,AUTO-R:0.06和0.08在WA和BD中,分别)。在两个杂交群体中,EP,AUTO-R,和SKEW估计比纯种低遗传(EP:[公式:见文本]≤0.07;和弹性指标性状:[公式:见文本]≤0.03),而LNVAR的[公式:见文字]估计值与纯种的相似或更高([公式:见文字]介于0.13至0.21之间)。在纯种和杂种中,估计弹性指标性状与EP以及彼此之间具有良好的遗传相关性。对于所有特征和两条线,纯种和杂种之间的遗传相关性的估计([公式:见文字])不同于1,范围从0.16到0.63。
    结论:这些结果表明,可以在层的育种程序中考虑基于EP数据的弹性选择。可以通过使用有关纯种的信息来实现杂种弹性的遗传改善,但是通过在育种计划中整合有关杂种的信息将大大增强。
    BACKGROUND: There is growing interest in using genetic selection to obtain more resilient farm animals (i.e. that are minimally affected by disturbances or rapidly recover from them). The aims of this study were to: (i) estimate the genetic parameters of resilience indicator traits based on egg production data, (ii) assess whether these traits are genetically correlated in purebreds and crossbreds, and (iii) assess the genetic correlations of these traits with egg production (EP) as total number of eggs between 25 and 83 weeks. Purebred hens (33,825 from a White Leghorn (WA) line and 34,397 from a Rhode Island (BD) line were housed in individual cages, while crossbred hens were housed in collective cages of 6 to 8 paternal half-sibs (12,852 WA and 3898 BD crossbred groups, where the name of the group refers to the line used as the sire). Deviations of a hen\'s weekly egg production from the average of the corresponding batch were calculated. Resilience indicator traits investigated were the natural logarithm of the variance (LNVAR), the skewness (SKEW), and the lag-one autocorrelation (AUTO-R) of these deviations.
    RESULTS: In both purebred lines, EP was estimated to be lowly heritable (WA: 0.11 and BD: 0.12). Resilience indicators were also estimated to be lowly heritable in both lines (LNVAR: 0.10 and 0.12, SKEW: 0.04 and 0.02, AUTO-R: 0.06 and 0.08 in WA and BD, respectively). In both crossbred groups, EP, AUTO-R, and SKEW were estimated to be less heritable than in purebreds (EP: [Formula: see text] ≤ 0.07; and resilience indicator traits: [Formula: see text] ≤ 0.03), while LNVAR had an [Formula: see text] estimate that was similar to or higher in crossbreds ([Formula: see text] ranged from 0.13 to 0.21) than in purebreds. In both purebreds and crossbreds, resilience indicator traits were estimated to have favorable genetic correlations with EP and between each other. For all traits and in both lines, estimates of genetic correlations between purebreds and crossbreds ([Formula: see text]) differed from 1 and ranged from 0.16 to 0.63.
    CONCLUSIONS: These results show that selection for resilience based on EP data can be considered in breeding programs for layers. Genetic improvement of resilience in crossbreds can be achieved by using information on purebreds, but would be greatly enhanced by the integration of information on crossbreds in breeding programs.
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  • 文章类型: Journal Article
    银屑病关节炎(PsA)是一种与银屑病相关的炎性关节炎。在北欧进行的HLA关联研究,将患者与对照人群进行比较,已经表明,HLA-C*06,HLA-B*57和HLA-B*27等位基因携带PsA的最高风险。这项回顾性关联研究比较了HLA-A,-B,-C,来自法国南部的500名患者的-DR等位基因,符合银屑病关节炎(PsA)CASPAR标准的人,2346名健康献血者控制,使用卡方检验。我们根据疾病将PsA患者分为三个不同的亚组:纯轴,纯粹的外围和组合的轴向和外围。轴向亚组与HLA-B*27(OR=16.3,p=2.7×10-28)及其单倍型:HLA-B*27-C*01(OR=12.4,p=1.7×10-12)和HLA-B*27-C*02(OR=8.7,p=10×10-9)相关。“轴向和外周”和“外周”亚组与HLA-C*06相关(分别为OR=1.5,p=3.6×10-10和OR=2.4,p=3.6×10-12)及其单倍型HLA-C*06-B*13(分别为OR=2.4,p=1.2×10-6和OR=2.8,p=6.4×10-11)。这项针对法国南部PsA队列的关联研究将HLA-C*06鉴定为外周PsA的标志物,将HLA-B*27鉴定为纯轴PsA的标志物。
    Psoriatic arthritis (PsA) is a type of inflammatory arthritis associated with psoriasis. HLA association studies performed in northern Europe, comparing patients with control populations, have shown that the highest risk for PsA is carried by HLA-C*06, HLA-B*57 and HLA-B*27 alleles. This retrospective association study compared HLA-A, -B, -C, and -DR alleles of 500 patients from southern France, who fulfilled the CASPAR criteria for Psoriatic Arthritis (PsA), with 2346 controls from healthy blood donors, using the chi-square test. We classified PsA patients into three different subgroups according to disease: purely axial, purely peripheral and combined axial and peripheral. The \'axial\' subgroup was associated with HLA-B*27 (OR = 16.3, p = 2.7 × 10-28) and its haplotypes: HLA- B*27-C*01 (OR = 12.4, p = 1.7 × 10-12) and HLA-B*27-C*02 (OR = 8.7, p = 10 × 10-9). The \'axial and peripheral\' and the \'peripheral\' subgroups were associated with HLA-C*06 (respectively OR = 1.5, p = 3.6 × 10-10 and OR = 2.4, p = 3.6 × 10-12) and its haplotypes HLA-C*06-B*13 (respectively OR = 2.4, p = 1.2 × 10-6 and OR = 2.8, p = 6.4 × 10-11). This association study on a southern French PsA cohort identifies HLA-C*06 as a marker for peripheral PsA and HLA-B*27 as a marker for purely axial PsA.
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  • 文章类型: Journal Article
    背景:如果在保护性育种项目中采用遗传驱动的干预措施,则可以通过在遗传上最有能力的个体中优先进行育种并延迟或完全减少近亲繁殖的不良影响来提高整体成功。
    结果:在本研究中,我们调查了在印度西孟加拉邦五个不同圈养设施中饲养的15只老虎的遗传组成,并报告了中等水平的遗传变异。我们根据个体遗传属性确定了五只老虎,这些老虎可能会优先用于未来的育种或动物交换计划。被囚禁的一阶和二阶相关个体的发生需要管理方面的关注,并且应该考虑到他们的直接遗传背景进行配对。
    结论:以老虎为例,我们强调使用遗传评估和必要性来验证研究簿记录,以制定适应性管理策略,以长期保护和管理感兴趣的物种。
    BACKGROUND: Genetics driven interventions if adopted in conservation breeding projects may enhance the overall success by prioritizing breeding among genetically most competent individuals and delaying or completely diminishing the ill effects of inbreeding.
    RESULTS: In the present study, we investigated genetic make-up of 15 tigers housed at five different captive facilities of West Bengal in India and report the moderate level of genetic variation. We identified five tigers based on individual genetic attributes that may be prioritized for future breeding or animal exchange programmes. The occurrence of first and second order related individuals in captivity require management attention and they should be paired considering their immediate genetic background.
    CONCLUSIONS: Considering tiger as a case study, we highlight the use of genetic assessment and necessity to validate the studbook records in formulating adaptive management strategies for long-term conservation and management of species of interest.
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  • 文章类型: Journal Article
    结论:在拟南芥和salsuginia中的ALDH7B4启动子分析显示,遗传背景和启动子结构都有助于不同物种响应胁迫的基因表达。在对盐度敏感和耐盐植物物种的比较中,许多基因受到差异调节。醛脱氢酶7B4(ALDH7B4)基因在拟南芥中具有膨胀反应性,并在植物中编码高度保守的解毒酶。这项研究比较了拟南芥(对盐度敏感)和耐盐度近亲Eutremasalsuginium中的ALDH7B4基因。在E.salsuggineum中的EsALDH7B4是AtALDH7B4的直系同源物,表达也是盐度,干旱,伤口反应灵敏。然而,沙糖大肠杆菌需要较高的盐度胁迫来诱导EsALDH7B4转录反应。由启动子AtALDH7B4或EsALDH7B4驱动的GUS表达在300mMNaCl处理下在拟南芥中被诱导,而在S.salsuginea中需要600mMNaCl处理,遗传背景在基因表达调控中起着至关重要的作用。ALDH7B4的启动子序列不如蛋白质编码区保守。将一系列EsALDH7B4启动子缺失片段与GUS报告基因融合,并在拟南芥中测定启动子活性。含有两个保守的含ACGT基序的启动子区域被鉴定为对于胁迫诱导是必需的。此外,在EsALDH7B4启动子中富含38bp的“TC”基序,AtALDH7B4启动子缺失,对EsALDH7B4表达产生负面影响。MYB样转录因子被鉴定为结合“TC”基序并抑制EsALDH7B4启动子活性。这项研究揭示了遗传背景和顺式作用元件协调调节基因表达。
    CONCLUSIONS: ALDH7B4 promoter analysis in A. thaliana and E. salsugineum reveals that both genetic background and promoter architecture contribute to gene expression in response to stress in different species. Many genes are differentially regulated in a comparison of salinity-sensitive and salinity-tolerant plant species. The aldehyde dehydrogenase 7B4 (ALDH7B4) gene is turgor-responsive in A. thaliana and encodes a highly conserved detoxification enzyme in plants. This study compared the ALDH7B4 gene in A. thaliana (salinity-sensitive) and in the salinity-tolerant close relative Eutrema salsugineum. EsALDH7B4 in E. salsugineum is the ortholog of AtALDH7B4 and the expression is also salinity, drought, and wound responsive. However, E. salsugineum requires higher salinity stress to induce the EsALDH7B4 transcriptional response. The GUS expression driven either by the promoter AtALDH7B4 or EsALDH7B4 was induced under 300 mM NaCl treatment in A. thaliana while 600 mM NaCl treatment was required in E. salsugineum, suggesting that the genetic background plays a crucial role in regulation of gene expression. Promoter sequences of ALDH7B4 are less conserved than the protein coding region. A series of EsALDH7B4 promoter deletion fragments were fused to the GUS reporter gene and promoter activity was determined in A. thaliana. The promoter region that contains two conserved ACGT-containing motifs was identified to be essential for stress induction. Furthermore, a 38 bp \"TC\" rich motif in the EsALDH7B4 promoter, absent from the AtALDH7B4 promoter, negatively affects EsALDH7B4 expression. A MYB-like transcription factor was identified to bind the \"TC\" motif and to repress the EsALDH7B4 promoter activity. This study reveals that genetic background and cis-acting elements coordinately regulate gene expression.
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  • 文章类型: Journal Article
    Mass spawning in fish culture often brings about a marked variance in family size, which can cause a reduction in effective population sizes in seed production for stock enhancement. This study reports an example of combined pedigree information and gene expression phenotypes to understand differential family survival mechanisms in early stages of Pacific bluefin tuna, Thunnus orientalis, in a mass culture tank. Initially, parentage was determined using the partial mitochondrial DNA control region sequence and 11 microsatellite loci at 1, 10, 15, and 40 days post-hatch (DPH). A dramatic proportional change in the families was observed at around 15 DPH; therefore, transcriptome analysis was conducted for the 15 DPH larvae using a previously developed oligonucleotide microarray. This analysis successfully addressed the family-specific gene expression phenotypes with 5739 differentially expressed genes and highlighted the importance of expression levels of gastric-function-related genes at the developmental stage for subsequent survival. This strategy demonstrated herein can be broadly applicable to species of interest in aquaculture to comprehend the molecular mechanism of parental effects on offspring survival, which will contribute to the optimization of breeding technologies.
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  • 文章类型: Journal Article
    Background and Objectives: No data are available on whether the heritability of left ventricle (LV) systolic and diastolic parameters are independent of each other. Therefore, our aim was to assess the magnitude of common and independent genetic and environmental factors defining LV systolic and diastolic function. Materials and Methods: We analyzed 184 asymptomatic twins (65% female, mean age: 56 ± 9 years). Transthoracic echocardiography was performed to measure LV systolic (global longitudinal and circumferential strain; basal and apical rotation) and diastolic (early diastolic velocity of mitral inflow and lateral mitral annulus tissue; deceleration time and early diastolic strain rate) parameters using conventional and speckle-tracking echocardiography. Genetic structural equation models were evaluated to quantify the proportion of common and specific genetic (Ac, As) and environmental factors (Ec, Es) contributing to the phenotypes. Results: LV systolic parameters had no common genetic or environmental heritability (Ac range: 0-0%; Ec range: 0-0%; As range: 57-77%; Es range: 24-43%). Diastolic LV parameters were mainly determined by common genetic and environmental effects (Ac range: 9-40%; Ec range: 11-49%; As range: 0-29%; Es range: 0-51%). Systolic parameters had no common genetic or environmental factors (Ac = 0%; Ec = 0%) with diastolic metrics. Conclusions: Systolic LV parameters have a strong genetic predisposition to any impact. They share no common genetic or environmental factors with each other or with diastolic parameters, indicating that they may deteriorate specifically to given effects. However, diastolic functional parameters are mainly affected by common environmental influences, suggesting that pathological conditions may deteriorate them equally. Estimation of the genetic and environmental influence and interdependence on systolic and diastolic LV function may help the understanding of the pathomechanism of different heart failure classification types.
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  • 文章类型: Journal Article
    六价铬[Cr(VI)]是一种常见的环境污染物。然而,对Cr(VI)胁迫下微生物进化的遗传基础以及先前的进化史对Cr(VI)胁迫下后续进化的影响知之甚少。在这项研究中,寻常脱硫弧菌希登伯勒(DvH),一种硫酸盐还原细菌模型,实验进化了600代。通过进化三个基因不同的DvH克隆的复制种群,包括祖先(AN,没有先前的实验进化史),非应激进化的EC3-10和盐应激进化的ES9-11,适应性的贡献,机会,并且能够解剖Cr(VI)胁迫下进化的预先存在的遗传差异。在大多数进化种群中观察到Cr(VI)胁迫下显着减少的滞后期,而Cr(VI)减少率增加主要在EC3-10和ES9-11进化而来的种群中观察到。起始克隆中预先存在的遗传差异对滞后期的变化显示出强烈的影响,增长率,和Cr(VI)还原率。此外,从不同起始克隆进化而来的群体的基因组突变谱有显著差异。共有14个新突变基因在至少两个进化种群中获得突变,表明它们在Cr(VI)适应中的重要性。这些基因之一的框内缺失突变,铬酸盐转运蛋白基因DVU0426表明它在Cr(VI)耐受中起重要作用。总的来说,我们的研究确定了Cr(VI)耐受性的潜在关键功能基因,并证明了在Cr(VI)胁迫条件下预先存在的遗传差异在进化中的重要作用。铬是土壤和地下水中最常见的重金属污染物之一。以前报道了普通脱硫弧菌在重金属生物修复中的潜力,例如Cr(VI)还原;但是,与Cr(VI)抗性有关的关键功能基因的实验证据在很大程度上是未知的。鉴于自然界中微生物种群的遗传差异,关于这种差异如何影响微生物对诸如Cr(VI)胁迫之类的新环境的适应的知识非常有限。利用我们之前的研究,在Cr(VI)胁迫下繁殖了三组具有或不具有先前实验进化史的普通D.vulgarisHildenborough种群600代。进化种群的全种群基因组重测序揭示了Cr(VI)耐受性提高的潜在基因组变化。在表型和遗传水平上都证明了起始克隆中预先存在的遗传差异对Cr(VI)胁迫条件下的进化的强烈影响。
    Hexavalent chromium [Cr(VI)] is a common environmental pollutant. However, little is known about the genetic basis of microbial evolution under Cr(VI) stress and the influence of the prior evolution histories on the subsequent evolution under Cr(VI) stress. In this study, Desulfovibrio vulgaris Hildenborough (DvH), a model sulfate-reducing bacterium, was experimentally evolved for 600 generations. By evolving the replicate populations of three genetically diverse DvH clones, including ancestor (AN, without prior experimental evolution history), non-stress-evolved EC3-10, and salt stress-evolved ES9-11, the contributions of adaptation, chance, and pre-existing genetic divergence to the evolution under Cr(VI) stress were able to be dissected. Significantly decreased lag phases under Cr(VI) stress were observed in most evolved populations, while increased Cr(VI) reduction rates were primarily observed in populations evolved from EC3-10 and ES9-11. The pre-existing genetic divergence in the starting clones showed strong influences on the changes in lag phases, growth rates, and Cr(VI) reduction rates. Additionally, the genomic mutation spectra in populations evolved from different starting clones were significantly different. A total of 14 newly mutated genes obtained mutations in at least two evolved populations, suggesting their importance in Cr(VI) adaptation. An in-frame deletion mutation of one of these genes, the chromate transporter gene DVU0426, demonstrated that it played an important role in Cr(VI) tolerance. Overall, our study identified potential key functional genes for Cr(VI) tolerance and demonstrated the important role of pre-existing genetic divergence in evolution under Cr(VI) stress conditions. IMPORTANCE Chromium is one of the most common heavy metal pollutants of soil and groundwater. The potential of Desulfovibrio vulgaris Hildenborough in heavy metal bioremediation such as Cr(VI) reduction was reported previously; however, experimental evidence of key functional genes involved in Cr(VI) resistance are largely unknown. Given the genetic divergence of microbial populations in nature, knowledge on how this divergence affects the microbial adaptation to a new environment such as Cr(VI) stress is very limited. Taking advantage of our previous study, three groups of genetically diverse D. vulgaris Hildenborough populations with or without prior experimental evolution histories were propagated under Cr(VI) stress for 600 generations. Whole-population genome resequencing of the evolved populations revealed the genomic changes underlying the improved Cr(VI) tolerance. The strong influence of the pre-existing genetic divergence in the starting clones on evolution under Cr(VI) stress conditions was demonstrated at both phenotypic and genetic levels.
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