Application of the rpoS gene for the detection of Vibrio anguillarum in flounder and prawn by polymerase chain reaction

Vibrio anguillarum , an opportunistic fish pathogen, is the main species responsible for vibriosis, a disease that affects feral and farmed fish and shellfish, and causes considerable economic losses in marine aquaculture. In this study, we used polymerase chain reaction (PCR) to detect V. anguillarum . PCR specificity was evaluated by amplifying the rpoS gene, a general stress regulator, in six strains of V. anguillarum and 36 other bacterial species. PCR amplified a species-specific fragment (689 bp) from V. anguillarum . Furthermore, the PCR assay was sensitive enough to detect rpoS expression from 3 pg of genomic DNA , or from six colony-forming units (CFU) mL⁻¹ of cultured V. anguillarum . However, the assay was less sensitive when genomic DNA from the infected flounder and prawn was used (limit of detection, 50 ng and 10 ng g⁻¹ tissue, respectively). These data demonstrate that PCR amplification of the rpoS gene is a sensitive and species-specific method to detect V. anguillarum in practical situations.     

Mitochondrial DNA deletion of the brain tissue of aged rats with learning and memory deficit

AIM and METHODS: The ratio of mitochondrial DNA (mtDNA) deletion was measured to find the relationship between mtDNA deletion and aged learning and memory deficit. The aged rats were divided into two groups, aged learning and memory deficit group and aged learning and memory normal group. The ratio of mtDNA deletion was measured by dilution polymerase chain reaction. RESULTS: There are deleted mtDNA (about 4834 bp) in the cerebral cortex, hippocampus and cerebellum of both young and aged rats. The ratios of deleted mtDNA were similar in the cerebral cortex,hippocampus and cerebellum of young rats (about 0.00018%). The ratio mtDNA of aged learning and memory normal rats had increased by five-fold in the cerebral cortex and hippocampus, or one-fold in the cerebellum over young rats. The ratio of aged learning and memory dificit rats had increased by one-fold in the cerebral cortex or 0.8-fold in the hippocampus or two-fold in the cerebellum over aged learning and memory normal rats.CONCLUSIONS: There was really the increase of mtDNA in aging rat brain. And this increase was double in amount in aged learning and memory deficit rats compared to the normal learning and memory aged rats. It is suggested that the mtDNA deletions in the brain regions associated with learning and memory may be contributed to the cellular and molecular mechanism of learning and memory deicit with aged rats.     

氯虫苯甲酰胺和氟虫腈对黏虫细胞色素P450基因表达的影响

为筛选出黏虫Mythimna separata参与杀虫剂解毒代谢的主效细胞色素P450基因,采用叶片浸渍法测定了用于处理黏虫3龄幼虫的亚致死浓度,通过构建转录组测序文库并结合数字基因表达(digital gene expression,DGE)对不同处理的黏虫进行测序,并运用实时荧光定量PCR(realtime quantitative polymerase chain reaction,RT-qPCR)技术验证12个P450基因的表达情况。结果表明,用于处理黏虫的氯虫苯甲酰胺和氟虫腈亚致死浓度LC_(10)分别为0.15、13.66 mg/L;对照样品、氟虫腈处理样品和氯虫苯甲酰胺处理样品分别获得59 521 504、64 838 148和41 722 990个原始序列数据,分别获得57 441 216、62 368 912和40 285 164个过滤后的序列数据;过滤后的序列长度分别为8.62、9.36和6.04 G;碱基错误率均为0.02%;Phred数值大于20、30的碱基占总碱基的百分比均高于90.59%;鸟嘌呤+胞嘧啶(guanine cytosine,GC)含量分别为47.16%、48.94%和47.55%,表明转录组测序质量较高;黏虫受氯虫苯甲酰胺胁迫后,29个P450基因表达量上调,27个P450基因表达量下调;黏虫受氟虫腈胁迫后,23个P450基因表达量上调,26个P450基因表达量下调;12个P450基因表达量的RT-qPCR技术检测结果与DGE测序文库显示的结果基本一致。     

面向冷链物流农产品品质感知的TTI动态校准方法

时间-温度指示器(TTI)是一种可以跟踪冷链物流温度历程的智能装置,可以指示相应的农产品品质。但现有的TTI匹配条件在一定程度上限制了TTI的应用范围,即使TTI满足了传统匹配条件的要求,但应用效果也会受到农产品采收品质波动的影响。通过使用反应动力学方程和等量线方法,在原有的匹配过程中引入了TTI的校准过程,并借此推导TTI匹配所需的基本条件,以及校准过程所需的参数。结果表明,TTI匹配性判断所需的基本条件仅为农产品品质与TTI的反应活化能相等,或两者等量线存在比例关系。在此前提下,利用公式推导或等量线的绘制过程,可以求得静态校准和动态校准时所需的相关参数,经过校准后的TTI即可与对应的食品完成匹配。校准过程的引入可以显著扩大TTI的适用范围。除此之外,动态校准模型还可以缩小处于变化中的TTI和农产品对应品质之间的差值,提高TTI指示货架期的精确性。最后,通过使用两种酶型TTI、两种不同激活条件的化学型TTI和玫瑰香葡萄进行验证实验,实验结果证明经过合理校正之后TTI的等量线普遍与玫瑰香葡萄的品质等量线更接近,对其指示效果精准。     

4CML-1000型链耙式地膜回收机设计与试验优化

为了解决传统搂耙式地膜回收机卸膜和装箱困难、作业连续性差等问题,设计了一种链耙式地膜回收机,可以连续实现搂膜集膜、输膜抖土、卸膜过程。该回收机主要由机架、起膜铲、链耙、集膜箱等部件组成。为了使地膜回收机的性能达到最佳,首先在土槽实验室内对回收机的结构参数和工作参数分别进行了单因素试验和响应曲面优化试验,通过土槽试验得到地膜回收率、脱膜率、夹带土壤质量3个指标的二次回归方程、响应优化曲面及最佳参数组合。最佳参数组合为:耙齿总成间距300 mm,单排耙齿数5个,耙齿入土深度84.41 mm,回收机前进速度2.542 km/h,链耙线速度0.417 m/s。通过大田验证试验,得到优化后的地膜回收机性能指标为:地膜回收率90.2%,脱膜率88.1%,夹带土壤质量0.41 kg/m。大田试验表明,链耙式地膜回收机满足生产要求。     

灰色-马尔柯夫链预测水稻产量的方法及其应用

将灰色系统预测模型GM(1,1)与马尔柯夫链相结合,建立玉林市早稻产量预测模型。应用结果表明:(1)模型具有灰色微分动态模型的特点,反映了产量变化的灰色过程;(2)应用马尔柯夫链对该模型所产生的误差进行修正,克服了GM模型误差较大等缺点,大大提高了预测精度,(3)灰色系统理论与随机过程理论相结合,互相取长补短,为统计理论发展开创了新的路径,也为产量预测预报提供了新的方法。     

玉米组蛋白H_3和H_4基因的克隆

本文以λEMBL3为克隆栽体,构建了玉米(Zea mays)基因组文库,通过人工合成的探针进行原位杂交和斑点杂交,从文库中筛选到4个含有组蛋白H_3基因的阳性克隆。另外,通过多聚酶链式反应(PCR),从玉米核DNA中扩增了组蛋白H_4基因。这些基因可以在转基因植物研究中作为辅助序列提高外源基因的整合频率。     

硒从土壤向食物链的迁移

硒是生物必需的微量营养元素 ,已经得到公认 ,硒从土壤向食物链的迁移状况直接关系到动物和人的健康。通过食物链 ,动物和人获得适合于健康需求的硒是最为安全和可行的