中美基因合作研究引发争议的思考

以案例分析的方式,对“安徽基因事件”中引发争议的关于科学家的责任、国际合作中本国基因资源流失以及媒体是否应对科学进行调查等问题,进行了剖析与思考。指出:在大科学时代,科学家应肩负起对科学和社会的双重责任;严格审查、加强监管是防止基因资源大量流失的重要手段;对科学进行调查,不仅是媒体更应是科学组织内部的责任。

藜叶片响应出芽短梗霉菌侵染内参基因筛选及光合作用相关基因表达分析

【目的】筛选适合出芽短梗霉菌株PA-2侵染藜的稳定表达的最适内参基因,并进行PA-2侵染下藜光合作用相关基因的表达分析验证。【方法】分别以菌株PA-2孢子侵染0、1、3、5、7 d的藜叶片和正常生长藜的根、茎、叶为供试材料,通过qRT-PCR技术和Ct值评估3个候选内参基因GAPDH、β-ACTIN、β-TUBULIN的表达稳定性,并利用筛选出的内参基因,对藜光合作用相关基因(LFRN、MDH、PetC、psaA、CAB40、psaN、BHY和MO_(2))的表达水平进行定量分析。【结果】在菌株PA-2侵染藜不同时间点和不同组织的样本中,藜最适内参基因为GAPDH,可用于后续分析光合作用相关基因的表达水平。以GAPDH作为内参基因检测8个光合作用相关基因的表达水平,在不同侵染时间点,8个光合作用相关基因的表达量均出现不同程度的下调,除MDH基因外,其余基因均在5 d时达到最低水平。其中PctC、psaN、CAB40、BHY、MO_(2)基因在藜受侵染0~1 d中下调表达,在3 d达到较高水平,后期表达量下调;pasA先上调表达后下调表达;LFRN在受侵染后持续下调表达;MDH在受侵染后先显著下调,在3 d达到较低水平,后上调表达。在藜受侵染的不同组织中,8个基因在藜叶中均有大量表达,其中MDH基因在茎中大量表达,PctC和CAB40在根中表达量最低,除MDH基因外,其余7个基因在不同组织中的表达量高低排序为:叶>茎>根。【结论】本研究为后续利用qRT-PCR分析藜基因表达及研究PA-2致病机理奠定基础。

基于课程的本科生参与科研训练模式研究——基于全美基因组学课程合作组织(GEP)

推动本科生参与科研是高等教育改革的重要内容。运用个案研究方法,选择全美基因组学课程合作组织为案例,以“基于课程的本科生参与科研训练模式”(CUREs)作为主要分析单元,构建了“结构—功能—优势”研究理论框架,分析了CUREs模式的结构功能和比较优势,提出了中国高校本科生科研实践行动建议框架设想,一是重构包容性和创新性的本科生科研训练目标体系,二是设计信息化和平台型的本科生科研训练结构体系,三是构建育人性和真实性的本科生科研训练功能体系。

紫细菌光合机构及光合作用基因的表达调控

紫细菌是研究细菌光合作用的重要生物。介绍了紫细菌光合机构捕光色素蛋白复合体Ⅰ(light-harvesting I)、捕光色素蛋白复合体Ⅱ(light-harvesting II)和光化学反应中心(reaction center)的结构,并探讨了其光合作用基因的转录调控机制,重点阐述了PpsR/AppA系统对紫细菌光合作用基因的转录调控。

噬藻体光合作用基因研究

感染原绿球藻和聚球藻的噬藻体基因组中普遍存在与psbA、psbD和hli等同源的基因,这些基因编码的蛋白参与光合作用,是光合成反应中心II(photosystem II,PSII)的重要组成成分,在噬藻体感染蓝藻过程中可能发挥着重要的作用。一些假说认为这些基因可能来自于宿主并发生共进化。因此,光合作用基因的功能、起源与演变及基因多样性分布引起了人们的关注。

不同温度对苋菜光合特性及光合作用相关基因表达的影响

以苋菜(Amaranthus tricolor Linn.)品种‘苏苋1号’(‘Suxian No.1’)为试验材料,比较了不同温度〔25℃(对照)、20℃、15℃和10℃〕处理下苋菜株高以及叶片中甜菜色素含量、叶绿素含量和叶绿素荧光参数的变化,并探究了温度对苋菜光合特性及光合作用相关基因表达的影响。结果显示:处理3和6 d的苋菜株高以及叶片中甜菜色素和叶绿素含量随着温度降低呈现降低的趋势,叶片的PSⅡ最大光化学效率(F_(v)/F_(m))、PSⅡ实际光量子产额〔Y(Ⅱ)〕、相对电子传递速率(rETR)、非光化学淬灭系数(qN)和调节性能量耗散的量子产量〔Y(NPQ)〕总体呈现波动降低的趋势,非调节性能量耗散的量子产量〔Y(NO)〕呈现波动升高的趋势;其中,15℃和10℃处理下苋菜的株高以及叶片中甜菜色素和叶绿素含量极显著低于对照,10℃处理下叶片的F_(v)/F_(m)、Y(Ⅱ)、rETR、qN和Y(NPQ)值总体极显著低于对照,Y(NO)值则极显著高于对照。qRT-PCR结果显示:总体上看,苋菜叶片AtrPPCK、AtrPEPC、AtrMDH、AtrNADP-MDH、AtrNAD-ME、AtrNADP-ME和AtrPPDK基因的相对表达量在多数温度下处理3和6 d与对照有显著差异;温度较低(10℃)会抑制除了AtrPPCK基因外的其他基因的表达,随着处理时间延长,基因相对表达量略有回升。相关性分析结果显示:温度与处理3和6 d苋菜的株高以及叶片中甜菜色素含量、叶绿素含量和多数叶绿素荧光参数呈极显著或显著相关。综合分析结果显示:低温会降低苋菜的叶绿素含量,破坏光合系统,抑制光合作用相关基因的表达,从而降低甜菜色素含量,抑制苋菜生长。

聚六亚甲基双胍对蛋白核小球藻的毒性效应研究

聚六亚甲基双胍(polyhexamethylene biguanide,PHMB)是一种高分子聚合物杀菌消毒剂,在医药、日用化工和水产养殖等行业广泛应用。为探究PHMB对水生植物的毒性效应,设置0、1、2、4 mg·L^(-1)浓度的PHMB对蛋白核小球藻(Chlorella pyrenoidosa)进行0、3、6和9 d的胁迫试验。结果表明:PHMB对蛋白核小球藻的生长具有抑制作用,且随胁迫浓度的升高而增强。PHMB显著降低蛋白核小球藻叶绿素a和b含量,引起藻细胞的细胞壁开裂和内含物外渗,损伤细胞器结构。PHMB显著降低蛋白核小球藻中抗氧化酶超氧化物歧化酶和谷胱甘肽过氧化物酶活性,并引起丙二醛含量升高。对蛋白核小球藻光合作用相关基因pbsA、rbcL和rbcS的表达检测发现,这些基因在低浓度的PHMB处理后表达升高,而在高浓度的PHMB处理后表达下降,说明小球藻对PHMB胁迫产生反馈调节。综上,PHMB可抑制蛋白核小球藻的光合作用及生长,为PHMB的生态风险评估提供了理论依据。

新冠疫情背景下美台基因科技合作新趋势及其影响

20世纪90年代以来,美台基因合作持续升温,初步形成全方位合作模式。新冠疫情暴发后,美台双方进一步联手推进基因技术在核酸检测、疫苗研发、药物生产等方面的运用,并强化相关领域的产学联结。在中美战略竞争背景下,美台基因科技合作正在呈现"基因搭台、政治唱戏"新态势,双方借助这一非传统安全合作提升实质关系,其影响可能向政治军事领域外溢,从而为台海局势带来新的变数。

Analysis on Interaction between Genotype of Four Main Flavonoids of Barley Grain and Environment

[Objective] This study aimed to analyze the interaction between genotype of flavonoids of barley grain and environment, to increase the flavonoid content of barley grain in cultivation and breeding. [Method] In this study, the content of cate- chin, myricetin, quercetin and kaempferol of barley grain planted in Kunming, Qujing and Baoshan were determined by HPLC, and the genotype, environment, genotype- environment interaction of the flavonoid content of barley grain were analyzed. [Result] According to the experimental results, the genotype variance, environmental variance and G x E interaction variance of catechin and kaempferol contents show the same trend： genotype variation 〉 environmental variation 〉 G × E interaction variation, which all reach a extremely significant level; the genotype variance, envi- ronmental variance and G × E interaction variance of quercetin and total flavonoid contents show the same trend： genetype variation 〉 G × E interaction variation 〉 environmental variation, which all reach a extremely significant level; the genotype variance and environmental variance of myricetin content both reach a extremely sig- nificant level, while the G × E interaction variance reaches a significant level, showing an order of genotype variation 〉 environmental variation 〉 G × E interaction variation; the genotype variance, environmental variance and G x E interaction vari- ance of total flavonoid content show an order of genotype variation 〉 environmental variation 〉 G × E interaction variation. Among different barley varieties, Ziguang- mangluoerling and Kuanyingdamai in Qujing, Kunming and Baoshan have relatively high content of quercetin, while other barley varieties barely contain any quercetin. The grains of Ziguangmangluoerling and Kuanyingdamai are purple, while the grains of other barley varieties are yellow. [Conclusion] Four main flavonoids and the total flavonoids of barley grain are mainly under genetic control and affected by genetic- environment interactions; the purple barley grains contain high content of quercetin.

乙草胺对蛋白核小球藻的毒性效应研究

乙草胺是我国使用量最大的除草剂之一,在水体中广泛存在。已有研究证明,乙草胺对人类、老鼠和鱼类具有毒害效应,而关于其对浮游植物影响的研究较少。以蛋白核小球藻(Chlorella pyrenoidosa)为模型,使用1~10000μg·L-1的乙草胺对其进行7 d的暴露实验,考察小球藻生长性能、叶绿素含量、光合作用产氧量以及光合作用相关基因(pbsA、rbcL和rbcS)表达的变化。结果表明,较低浓度的乙草胺可刺激蛋白核小球藻生长,而较高浓度乙草胺则会抑制其生长;并且乙草胺会通过影响小球藻叶绿素的含量而影响光合作用产氧量;小球藻光合作用相关基因pbsA、rbcL和rbcS表达大多显著上升,这可能是对乙草胺胁迫响应的反馈调节。研究表明,乙草胺会对蛋白核小球藻的生长及光合作用产生影响。

Characteristics of photosynthesis in rice plants transformed with an antisense Rubisco activase gene

Transgenic rice plants with an antisense gene inserted via Agrobacterium tumefaciens were used to explore the impact of the reduction of Rubisco activase (RCA) on Rubisco and photosynthesis. In this study, transformants containing 15% to 35% wild type Rubisco activase were selected, which could survive in ambient CO2 concentration but grew slowly compared with wild type controls. Gas exchange measurements indicated that the rate of photosynthesis decreased sig- nificantly, while stomatal conductance and transpiration rate did not change; and that the intercellular CO2 concentration even increased. Rubisco determination showed that these plants had approximately twice as much Rubisco as the wild types, although they showed 70% lower rate of photosynthesis, which was likely an acclimation response to the reduction in Rubsico activase and/or the reduction in carbamylation.

Determination of Selected Toxic Elements in Apples from Organic Farming

Due to the elevated ecological awareness nowadays the consumption of products of organic agriculture is increasing. Organic farming means excluding the use of synthetic inputs, such as synthetic fertilizers and pesticides or genetically modified organisms, but there are only a few regulations regarding heavy metal concentrations in soils. Thus a not negligible uptake of metals from the soil where the apple trees are grown may occur. Furthermore inorganic copper compounds being traditional fertilizers for apple trees are not considered as synthetic fertilizers, thus they are still used in organic apple farming for soil or foliar application. Thus also apples produced by organic agriculture may contain toxic elements, such as cadmium, chromium, copper, and lead. The concentrations of these elements were determined in whole apples, as well as in the flesh and peel in order to estimate the possible risk for human health. Prior to analysis using ICP-AES samples underwent a microwave assisted digestion. The LODs obtained are below the recommended maximum levels in vegetables/fruits by WHO. In all samples no Cu, Cr, and Pb could be detected. Only Ca was found in the peel of about a third of samples investigated in concentrations between LOD and LOQ （1-3 μg/g）.

Identification of the development stage-specific factors in mouse fetal liver binding to the human β-globin gene promoter

In order to elucidate the molecular mechanisms of globin gene expression during embryonic development, the nuclear extracts from mouse hematopoietic tissue at different stages of development have been prepared. By using DNase I footprinting and gel mobility shift assays, the binding of protein factors in these extracts to the human βglobin promoter was analyzed. The differences in the binding patterns of protein factors during development were observed. An erythroid-specific and stage-specific nuclear protein in the nuclear extract from d 18 mouse fetal liver was identified, which can bind to the sequence (from -66bp to -90bp) of human β-globin promoter. We therefore speculate that the function of this cis-acting element may be similar to stage selector element (SSE) in chieken βA- promoter.

利用SSH文库技术分离鉴定常春藤应答甲醛胁迫相关基因

很多研究结果证实常春藤可以有效吸收气体甲醛,本研究结果表明常春藤叶片也可以有效吸收液体甲醛,甲醛吸收量和时间呈指数函数关系。2、4、6 mmol·L^(-1)液体甲醛处理均在常春藤叶片内诱发氧化胁迫,但2 mmol·L^(-1)液体甲醛胁迫在常春藤叶片内诱发的氧化胁迫水平较低。此外,2 mmol·L^(-1)液体甲醛胁迫还显著提高了常春藤叶片内可溶性糖和可溶性蛋白的含量,说明常春藤对2 mmol·L^(-1)液体甲醛胁迫的抗性较强。通过构建2 mmol·L^(-1)液体甲醛胁迫2~48 h常春藤叶片的正向SSH cDNA文库,分离鉴定常春藤叶片中的甲醛胁迫应答基因并对甲醛胁迫应答基因进行功能聚类,结果说明光合作用和代谢相关基因占的比例最大,表达分析结果证实光合作用和代谢相关基因在2 mmol·L^(-1)液体甲醛胁迫的不同阶段被诱导上调表达,这些基因的上调表达可能和甲醛在常春藤叶片内的代谢脱毒有关。此外,参与植物对多种生物和非生物胁迫应答的14-3-3蛋白基因(14-3-3p)也受2 mmol·L^(-1)液体甲醛胁迫的强烈诱导,该基因的上调表达可能参与甲醛胁迫下常春藤叶片内可溶性蛋白的合成与抗氧化系统活性的调控作用,是常春藤叶片应答甲醛胁迫的重要基因之一。

营养盐恢复对氮磷饥饿铜绿微囊藻生长的影响

在自然水体中微囊藻经常经历营养盐的限制和再补充,营养盐浓度的波动影响着微囊藻的生长和暴发.本文利用14C标记和荧光定量PCR研究了营养盐恢复对氮磷饥饿的铜绿微囊藻细胞生理和光合作用相关基因表达的影响.结果表明经过氮磷饥饿的铜绿微囊藻在补充营养盐后,都能快速生长,氮饥饿的藻细胞生长更快,但其经过快速增长期后很快开始衰亡.补充营养盐后,经过磷饥饿的藻细胞固碳能力和光合作用相关基因表达很快恢复至未经饥饿藻细胞的水平,而经过氮饥饿的藻细胞其固碳能力和相关基因虽然有很大提升,却难以恢复至未经饥饿的藻细胞的水平.这可能也是氮饥饿的藻细胞在饥饿解除后虽然能暂时地快速生长,但很快又进入衰亡的原因之一.

Polymeric prodrug for bio-controllable gene and drug co-delivery

A polymeric polyethylenimine(PEI)-based prodrug of anticancer doxorubicin(DOX)(PEI-hyd-DOX) was designed by attaching DOX to PEI via an acid-labile hydrazone bond, for the achievement of biocontrollable gene and drug co-delivery in response to the intracellular acid microenvironments in the late endosome/lysosome compartments. The cytotoxicity of PEI-hyd-DOX was evaluated by the MTT assay and the cellular uptake was monitored using confocal laser scanning microscopy. The polymeric prodrug can respond with a high sensitivity to the specific acid condition inside cells, thus permitting the precise biocontrol over intracellular drug liberation with high drug efficacy. The chemical attachment of drug molecules also led to the relatively reduced toxicity and the enhanced transfection efficiency compared with parent PEI. The resulting data adumbrated the potential of PEI-hyd-DOX to co-deliver DOX and therapeutic gene for the combination of chemotherapy and gene therapy.

Thymine DNA glycosylase promotes transactivation of β-catenin/TCFs by cooperating with CBP

Thymine DNA glycosylase CrDG）, an enzyme that initiates the repair of G/T and G/U mismatches, has been lately found crucial in em- bryonic development to maintain epigenetic stability and facilitate the active DNA demethylation. Here we report a novel role of TDG in Wnt signaling as a transcriptional coactivator of β-catenin/TCFs complex. Our data show that TDG binds to the transcriptional factor family LEF1/TCFs and potentiates β-catenin/TCFs transactivation, while TDG depletion suppresses Wnt3a-stimulated reporter activity or target gene transcription. Next, we show that CBP, a known coactivator, is also required for TDG function through forming a coopera- tive complex on target promoters. Moreover, there is an elevation of TDG levels in human colon cancer tissue, and knockdown of TDG inhibits proliferation of the colon cells. Overall, our results reveal that TDG, as a new coactivator, promotes β-catenin/TCFs transacti- vation and functionally cooperates with CBP in canonical Wnt signaUng.

Comparative transcriptomic insights into the mechanisms of electron transfer in Geobacter co-cultures with activated carbon and magnetite

Both activated carbon and magnetite have been reported to promote the syntrophic growth of Geobacter metallireducens and Geobacter sulfurreducens co-cultures, the first model to show direct interspecies electron transfer (DIET); however, differential transcriptomics of the promotion on co-cultures with these two conductive materials are unknown. Here, the comparative transcriptomic analysis of G. metallireducens and G. sulfurreducens co-cultures with granular activated carbon (GAC) and magnetite was reported. More than 2.6-fold reduced transcript abundances were determined for the uptake hydrogenase genes of G. sulfurreducens as well as other hydrogenases in those co-cultures to which conductive materials had been added. This is consistent with electron transfer in G. metallireducens-G. sulfurreducens co-cultures as evinced by direct interspecies electron transfer (DIET). Transcript abundance for the structural component of electrically conductive pili (e-pili), PilA, was 2.2-fold higher in G. metallireducens, and, in contrast, was 14.9-fold lower in G. sulfurreducens in co-cultures with GAC than in Geobacters co-cultures without GAC. However, it was 9.3-fold higher in G. sulfurreducens in co-cultures with magnetite than in Geobacters co-cultures. Mutation results showed that GAC can be substituted for the e-pili of both strains but magnetite can only compensate for that of G. sulfurreducens, indicating that the e-pili is a more important electron acceptor for the electron donor strain of G. metallireducens than for G. sulfurreducens. Transcript abundance for G. metallireducens c-type cytochrome gene GMET_RS14535, a homologue to c-type cytochrome gene omcE of G. sulfurreducens was 9.8-fold lower in co-cultures with GAC addition, while that for OmcS of G. sulfurreducens was 25.1-fold higher in co-cultures with magnetite, than in that without magnetite. Gene deletion studies showed that neither GAC nor magnetite can completely substitute the cytochrome (OmcE homologous) of G. metallireducens but compensate for the cytochrome (OmcS) of G. sulfurreducens. Moreover, some genes associated with central metabolism were up-regulated in the presence of both GAC and magnetite; however, tricarboxylic acid cycle gene transcripts in G. sulfurreducens were not highly-expressed in each of these amended co-cultures, suggesting that there was considerable redundancy in the pathways utilised by G. sulfurreducens for electron transfer to reduce fumarate with the amendment of GAC or magnetite. These results support the DIET model of G. metallireducens and G. sulfurreducens and suggest that e-pili and cytochromes of the electron donor strain are more important than that of the electron acceptor strain, indicating that comparative transcriptomics may be a promising route by which to reveal different responses of electron donor and acceptor during DIET in co-cultures.

jadR* and jadR2 act synergistically to repress jadomycin biosynthesis

The biosynthesis of antibiotics is controlled by cascade regulation involving cluster-situated regulators (CSRs) and pleiotropic regulators. Three CSRs have been identified in the jadomycin biosynthetic gene cluster, including one OmpR-type activator (JadR1) and two TetR-like repressors (JadR* and JadR2). To examine their interactions in jadomycin biosynthesis, a series of mutants were generated and tested for jadomycin production. We noticed that jadomycin production in the jadR*-jadR2 double mutant was increased dramatically compared with either single mutant. Transcriptional analysis showed that jadR* and jadR2 act synergistically to repress jadomycin production by inhibiting the transcription of jadR1. Furthermore, jadR* and jadR2 reciprocally inhibit each other. The complex interactions among these three CSRs may provide clues for the activation of the jadomycin gene cluster, which would otherwise remain silent without stimulation from stress signals.