Effects of tetrabrominated diphenyl ether and hexabromocyclododecanes in single and complex exposure to hepatoma HepG2 cells

This study was designed to determine cytotoxic effects of PBDE-47 and HBCDs individually or with a mixture of both compounds exposure to Hep G2 cells. The results showed PBDE-47 and HBCDs induced increase of nitric oxide synthase (NOS) activity, release of NO. dissipation of mitochondria membrane potential and cell apoptosis. Exposure to HBCDs induced ROS formation. Moreover, preincubation with PTIO (NO scavanger) and N-acetylcysteine (ROS scavanger) partially reversed cytotoxic effects of these compounds. The possible mechanism is that PBDE-47 and HBCDs could boost generation of NO and/or ROS, impact mitochondria, and result in start-ups of apoptosis program. Cells exposed to mixture of both compounds and each of them showed non-apoptotic rate significant difference, but the combination of them caused more adverse effects on cells. These results Suggest that PBDE-47 and HBCDs in single and complex exposure have the cytotoxic activity of anti-proliferation and induction of apoptosis in tumor cells in vitro. (C) 2008 Elsevier B.V. All rights reserved.

UV-B-induced Oxidative Damage and Protective Role of Exopolysaccharides in Desert Cyanobacterium Microcoleus vaginatus

UV-B-induced oxidative damage and the protective effect of exopolysaccharides (EPS) in Microcoleus vaginatus, a cyanobacterium isolated from desert crust, were investigated. After being irradiated with UV-B radiation, photosynthetic activity (Fv/Fm), cellular total carbohydrates, EPS and sucrose production of irradiated cells decreased, while reducing sugars, reactive oxygen species (ROS) generation, malondialdehyde (MDA) production and DNA strand breaks increased significantly. However, when pretreated with 100 mg/L exogenous EPS, EPS production in the culture medium of UV-B stressed cells decreased significantly; Fv/Fm, cellular total carbohydrates, reducing sugars and sucrose synthase (SS) activity of irradiated cells increased significantly, while ROS generation, MDA production and DNA strand breaks of irradiated cells decreased significantly. The results suggested that EPS exhibited a significant protective effect on DNA strand breaks and lipid peroxidation by effectively eliminating ROS induced by UV-B radiation in M. vaginatus.

Effects of hexachlorobenzene on antioxidant status of liver and brain of common carp (Cyprinus carpio)

Hexachlorobenzene (HCB)-induced oxidative damages have been published in rats while the effects have not yet been reported in fishes. Juvenile common carps (Cyprinus carpio) were exposed to waterborne HCB from 2 to 200 mu g l(-1) for 5, 10 or 20 days. Liver and brain were analyzed for various parameters of oxidative stress. There were no significant changes of glutathione (GSH) content and superoxide dismutase (SOD) activity in liver after 5 or 10 days exposure, whereas obvious drops were observed at higher concentrations after 20 days exposure. Significant decreases of GSH content and SOD activity in brain were found during all the exposure days. In brain, HCB also significantly elevated the contents of reactive oxygen species (ROS), thiobarbituric acid-reactive substances (TBARS, as an indicator of lipid peroxidation products), glutathione disulfide (GSSG), and activities of nitric oxide synthase (NOS), glutathione peroxidase (GPx), and glutathione reductase (GR), and inhibited activities of acetylcholinesterase (AchE) and glutathione S-transferase (GST). The results clearly demonstrated that environmentally possible level of HCB could result in oxidative stress in fish and brain was a sensitive target organ of HCB toxicity. (c) 2006 Elsevier Ltd. All rights reserved.

Effects of salt stress on carbohydrate metabolism in desert soil alga Microcoleus vaginatus Gom.

The effects of salt stress on carbohydrate metabolism in Microcoleus vaginatus Gom., a cyanobacterium isolated from desert algal crusts, were investigated in the present study. Extracellular total carbohydrates and exopolysaccharides (EPS) in the culture medium produced by M. vaginatus increased significantly during the growth phase and reached a maximum during the stationary phase. The production of extracellular carbohydrates also significantly increased under higher salt concentrations, which was attributed to an increase in low molecular weight carbohydrates. In the presence of NaCl, the production of cellular total carbohydrates decreased and photosynthetic activity was impaired, whereas cellular reducing sugars, water-soluble sugars and sucrose content and sucrose phosphate synthase activity increased, reaching a maximum in the presence of 200 mmol/L NaCl. These parameters were restored to original levels when the algae were transferred to a non-saline medium. Sodium and K+ concentrations of stressed cells decreased significantly and H+-ATPase activity increased after the addition of exogenous sucrose or EPS. The results suggest that EPS and sucrose are synthesized to maintain the cellular osmotic equilibrium between the intra- and extracellular environment, thus protecting algal cells from osmotic damage, which was attributed to the selective exclusion of cellular Na+ and K+ by H+-ATPase.

Salt tolerance of Microcoleus vaginatus Gom., a cyanobacterium isolated from desert algal crust, was enhanced by exogenous carbohydrates

Microcoleus vaginatus isolated from a desert algal crust of Shapotou was cultured in BG-11 medium containing 0.2mol l(-1) NaCl or 0.2mol l(-1) NaCl plus 100mg l(-1) sucrose, extracellular polymeric substances (EPS) or hot water-soluble polysaccharides (HWP), respectively. Photosynthetic oxygen evolution rates, photosystem 11 activity (Fv/Fm) and dark respiration of NaCl-stressed cells were enhanced significantly by the added sucrose or EPS under salt stress conditions (0.2mol l(-1) NaCl). Compared with cells treated with salt alone, sodium contents in cells reduced significantly; the content of cellular total carbohydrate did not change, and intracellular sucrose, water-soluble sugar increased significantly following the addition of exogenous carbohydrates. Sucrose synthase (SS) activity of NaCl-stressed cells increased following the addition of sucrose, and sucrose phosphate synthase (SPS) activity of NaCl-stressed cells increased following the addition of exogenous sucrose, EPS or HWP compared with cells stressed with NaCl only. The results suggested that the extruded EPS might be re-absorbed by cells of M. vaginatus as carbon source, they could increase salt tolerance of M. vaginatus through the changes of carbohydrate metabolism and the selective uptake of sodium ions. (C) 2003 Elsevier Science Ltd. All rights reserved.

基于GIS的区域土壤侵蚀模型设计

区域土壤侵蚀模型是国家和区域土壤侵蚀调查、水土保持宏观规划的支持工具。借鉴国外区域土壤侵蚀模型,以DEM栅格为空间单元,对区域土壤侵蚀的单元模型进行定量表达,包括降雨、植被截留、入渗,微地形填洼等,并利用GIS功能完成径流传递和汇集部分的计算,建立了区域土壤侵蚀模型。所建立模型在延河流域的试运算,结果接近现实,能反映土壤侵蚀时空分布趋势。模型的建立可为水土保持的宏观决策提供支持。

同源四倍体与二倍体水稻的遗传差异及产量、品质性状研究

本文以中国科学院成都生物研究所培育的同源四倍体水稻和二倍体水稻为材料，进行遗传差异及产量、品质性状的研究：1、以二倍体水稻为对照，研究了同源四倍体水稻在2004 年和2005 年的结实情况。结果同源四倍体的花粉育性、结实率均不同程度下降，尤其低代材料更是大幅度下降。F 检验表明，同源四倍体不同个体间的各产量性状均差异显著，说明其具有很大的遗传改良潜力。从1996 年到2005 年对部分同源四倍体水稻进行了连续选择改良，T 检验表明经过9 年的选择改良，其结实率显著提高。本文还对同源四倍体水稻各产量性状间的相关性进行了分析,结果结实率与花粉育性、穗着粒数、穗实粒数极显著相关；理论产量与花粉育性、有效穗数、穗着粒数、穗实粒数、结实率及千粒重极显著相关。i2、用(CT)n 微卫星标记和PCR-Acc Ι分子标记对40 份同源四倍体和14 份二倍体水稻Wx 基因进行研究。结果，(CT)n 微卫星标记检测，Wx 基因呈Wx1、Wx2 和Wx3 3 种多态性；PCR-Acc Ι 检测，Wx 基因表现为G-型和T-型。测定稻米直链淀粉含量(AC)、胶稠度(GC)和糊化温度(GT)，并探讨其与Wx 基因的关系，结果，二倍体和同源四倍体水稻均存在：Wx 基因型相同，AC 差异较小，Wx 基因型不同时，AC 差异较大，Wx1 基因型品种AC 最高， Wx2 基因型品种AC 次之，Wx3 基因型品种AC 最低；基因型相同时，同源四倍体AC 低于二倍体；同源四倍体与对应二倍体间，Wx 基因型相同时，AC 差异很小；而Wx 基因型发生变异时，AC 差异很大。同时，进行相关性分析，结果二倍体和四倍体水稻均存在AC、GC 与Wx 基因密切相关；而GT 与Wx 基因相关不显著。综合分析，(CT)n微卫星标记与PCR-Acc Ι 分子标记检测的相关系数为0.842，呈极显著正相关，可以将其结合起来进行同源四倍体新品种的选育和改良。3、利用RAPD 技术，对同源四倍体和二倍体水稻的遗传差异进行分析。17条引物在同源四倍体中扩增出178 条带（PPB＝81.5%），在二倍体中扩增出173条带（PPB＝76.3%）；同源四倍体和二倍体的Shannon 遗传多样性指数分别为0.4848 和0.4679，多态信息量分别为0.3301 和0.3216，遗传距离分别为0.3572和0.3460；同源四倍体与其对应二倍体间遗传距离为0.1914-0.4633，平均为0.2914。表明同源四倍体的遗传多样性高于二倍体，且同源四倍体与其二倍体之间存在较大的遗传差异，这些将为水稻品种改良和新品种选育提供科学依据。上述产量、品质性状及遗传差异分析的结果，不仅有利于加快同源四倍体水稻的遗传改良进程，而且为进一步研究、利用同源四倍体水稻奠定了初步基础。 AbstractStudy on genetic diversity, yield characters and quality traitsof autotetraploid and diploid riceLiu Yuhua (Botany)Directed by Associate Prof. Tu ShengbinIn this study, diploid and autotetraploid rice, which were cultivated in ChengduInstitute of Biology were analyzed in genetic diversity, yield characters and qualitytraits.In the study, 2 diploid and 29 autotetraploid rice(2n=4x=48) materials, including4 preliminary and 25 advanced generation, were investigated for yield characters.Compared with diploid check, the pollen fertility and seed set of autotetraploiddeclined dramatically, especially in preliminary generation. F-test indicated that therewere remarkable differences among different varieties, showing that autotetraploidmaterials had strong potential for improvement. From 1996 to 2005, someautotetraploid rice had been selected and improved. T-test showed that seed setincreased obviously. The relationships among yield characters of autotetraploid ricewere analyzed. Seed set was strongly correlated with pollen fertility, total grainnumber per panicle and productive grain number per panicle; theoretical yield wasstrongly correlated with pollen fertility, productive panicle number per plant, totalgrain number per panicle, productive grain number, seed set and 1000-grain weight.Wx genotypes of 40 autotetraploid rice and 14 diploid rice were tested by usingthe (CT)n microsatellite marker and a cleaved amplified polymorphic sequence(CAPS) molecular marker named PCR-Acc Ι. Three microsatellite alleles wereproduced, i.e. Wx1, Wx2 and Wx3 both in autotetraploid and in diploid rice.Comparatively, PCR- Acc Ι molecular marker produced two genotypes, G-type andT-type for both autotetraploid and diploid rice. In this study, amylose content (AC), gel of consistency (GC) and gelatinization temperature (GT) of rice grain weremeasured and their relationships with Wx alleles were analyzed. The results showedthat variation of AC between autotetraploid and diploid rice was small when they hadthe same Wx genotype. However, variation of AC turned to be large when the Wxgenotypes were different. Actually, AC met the maximum value in Wx1 varieties andWx2 varieties the middle and Wx3 varieties the minimum. And AC was lower inautotetraploid than in diploid. Correlation analysis was done in this experiment. ACand GC of rice grain were probably controlled by Wx gene or other gene whoselocation was strictly linked to Wx gene, while GT of rice was not. The correlationcoefficient between Wx genotypes which revealed by (CT)n microsatellite marker andPCR-Acc Ι molecular marker was 0.842 with significant level. That revealed aconsistent result between the two types of markers. So it was possible to utilize boththe two types of markers to select and promote germplasm of autotetraploid rice.RAPD molecular markers were used to analyze the genetic diversity betweendiploid and autotetraploid rice. 178 repeatable bands were detected through 17 RAPDprimers with percentage of polymorphic bands was 81.5% in autotetraploid rice while173 repeatable bands were detected with percentage of polymorphic bands was 76.3%in diploid rice. According to the measurement of Shannon index, polymorphicinformation content and genetic distance, genetic diversity of autotetraploid was on ahigher level, genetic variation between autotetraploid and diploid rice was relativelyhigh. All these contributed to the genetic selection and improvement in rice breeding.As mentioned above, the results are not only helpful to promote the process ofrice improvement, but also to confirm the basic for further study of autotetraploid rice.

RNAi沉默烟草GA 20-氧化酶基因研究

赤霉素是一种高效能的广谱植物生长调节剂，为五大植物激素之一，具有重要的生物学功能。目前利用赤霉素突变体研究生物合成途径和信号转导已经成为热点。 GA 20-氧化酶是GA生物合成中的一类关键酶，它位于GA合成途径的中心位置。本研究根据烟草（Nicotiana tabacum）GA 20-氧化酶基因序列，设计2对分别含有特定酶切位点的特异引物，以烟草基因组DNA为模板，扩增目的基因(约250 bp)片段。将正、反向目的片段分别插入中间载体的内含子两侧，再经BamH I和Sac I双酶切回收约700 bp的目的片段，插入到双元载体质粒p2355中，成功构建了含GA 20-氧化酶基因片段反向重复序列的植物表达载体p23700。分别将p2355质粒和p23700质粒导入根癌农杆菌（Agrobacterium tumefaciens）EHA105中并转化烟草叶片细胞，经卡那霉素选择培养，PCR及GUS组织染色鉴定，获得转基因烟草植株。以EHA105-p2355转化的烟草，获得41株转基因植株，均没有矮化表型；而以EHA105-p23700转化的烟草，获得转基因植株14株，其中具有矮化表型的烟草10株，表明反向重复序列转录产物能形成发夹RNA(hpRNA)，产生小分子干扰RNA（small interferring RNA，简称siRNA），干扰目的基因的表达。 赤霉素含量测定表明矮化植株中赤霉素合成途径的最终产物GA3总含量明显低于野生型烟草植株。荧光定量PCR结果表明，矮化转基因烟草的GA 20-氧化酶基因表达量受到明显抑制，表达量明显低于野生型对照。同时对上游内根-贝壳杉合成酶（Ent-kaurene synthase，KS）基因，下游的GA-3β羟化酶基因进行了RT-PCR分析，结果显示上游基因的表达没有规律性变化，而下游基因表达量亦降低。上述结果表明，GA 20-氧化酶基因的表达被有效地干扰了，表达受到抑制，从而影响植株体内GA3的合成，影响植株的生长发育，导致植株矮化。并推测，GA 20-氧化酶基因受到抑制，可能影响下游基因的表达。并且通过干旱胁迫测试，发现矮化植株相对于野生型植株及不含干扰片段的转基因植株，对干旱的耐受力有了很大的提高，具有更强的耐受力。 研究结果为进一步进行相关研究奠定基础。 Gibberellin(GA) is an efficient plant growth regulator. As one of five major plant hormones, it plays an important biological function. Using GA mutant for investigating biosynthetic pathways and signal transduction has become high lights. GA 20-oxidase is a crucial enzyme involved in gibberellin biosynthesis. According to tobacco (Nicotiana tabacum) GA 20-oxidase enzyme gene sequence and based on binary vector p2355, we constructed a plant expression vector p23700, which habors an inverted repeat DNA fragment of GA 20-oxidase gene drivered by Cauliflower mosaic virus promtor (CaMV 35Sp). Binary plasmid p2355 had no inverted repeat DNA fragment of GA 20-oxidase gene. The vector p2355 and p23700 were introduced into Agrobacterium tumefaciens EHA105 and tobacco leaf transformation was conducted. After selected by kanamycin and characterized by PCR and GUS hischemical reaction, transsgenic plants were obtained. Fourtheen transgenic plants, which were transformed by EHA105-p23700, were obtained. Among them, 10 were dwarf mutants. However, 41 transgenic plants with the same normal phenotype as wild type,which were transformed by EHA105-p2355, were obtained. Analysis of Gibberellin contents showed that it was lower in dwarf mutants than in normal phenotype plants. Moreover, comparing to normal phenotype plants including wild type and transgenic plants with no interference fragment, the drought tolerance of dwarf plants have greatly increased. And their proline content increased obviously after drought test. Fluorescence quantitative real time PCR (RT-PCR) showed that GA 20-oxidase gene expression was significantly inhibited in dwarf transgenic tobacco. Meanwhile, the expression of the upstream gene ent-kaurene synthase (KS) gene and downstream gene GA-3β hydroxylase gene was also detected by RT-PCR. The results presented that KS gene expression had no regular change while GA-3β hydroxylase gene expression reduced. It implied that inhibiting GA 20-oxidase gene probably reduce the expression of downstream genes. The results showed that the transcriptional products of the foreign inverted repeat fragment can form hairpin RNA (hpRNA) to induce RNAi. It presented that GA 20-oxidase gene expression was effectively interfered, resulting in reducing GA3 synthesis and inhibiting plant growth and development, then dwarf plants were produced. However, the dwarf plants had higher tolerance of drought.

辐射诱导的HeLa细胞旁效应信号通路研究

随着肿瘤认识的不断深入，肿瘤外科学、肿瘤放射治疗学、肿瘤化学治疗学构成了现代肿瘤治疗学的三大支柱，而放射治疗学的研究对于肿瘤的治疗有重要的临床意义。本文通过对HeLa进行辐射来观察其产生的旁效应信号通路，从而对临床工作的起到一定的帮助。辐照过的细胞通过释放信号分子引起周围未辐照细胞产生一系列的生物学反应的现象，称之为辐射诱导的旁效应。活性氧（Reactive oxygen species, ROS）和一氧化氮（Nitric oxide, NO）是辐射诱导的旁效应信号通路中的两个重要信号分子。本文研究了这两种重要的信号分子在辐射诱导的HeLa细胞旁效应信号通路中的关系。通过微核实验，我们发现X射线以及12C6+ 辐照过的HeLa细胞及其旁观者细胞的微核形成明显增加，而1%的二甲亚砜（Dimethyl sulfoxide，DMSO，ROS清除剂）预处理X射线辐照的细胞则显著抑制了受辐照细胞及其旁观者细胞的微核形成。1 Gy的X射线辐照能够抑制细胞的增殖速率而0.5%和1%的DMSO预处理则能减少X射线的增殖抑制作用，并且DMSO预处理的效果与浓度有关：1%的DMSO比0.5%的DMSO处理更大程度的恢复了受辐照细胞的增殖速率。另一方面，接受条件培养基（Conditioned medium）的旁观者细胞的增殖速率增加，而DMSO预处理产生条件培养基的受辐照细胞则使旁观者细胞的增殖速率降低，且DMSO预处理的效果同样与其浓度相关：浓度越高，条件培养基的刺激生长作用越小。Western blotting和DAF-FM DA荧光探针检测分别显示了辐照过后细胞的诱导型一氧化氮合酶（Inducible nitric oxide synthase, iNOS）和NO水平均升高，而DMSO预处理则降低其水平。因此，我们推测在X射线辐照的HeLa细胞旁效应信号通路当中ROS是NO的上游信号。另外，我们采用培养基转移后立即加DMSO或BMS－345541（IKK/NF-κB抑制剂）的方法研究了旁观者细胞当中的旁效应信号通路。我们发现DMSO和BMS－345541均显著抑制了旁观者细胞的NO水平。因此，在旁观者细胞当中ROS与NF-κB均为NO的上游信号

长期定位试验下施肥对潮棕壤活性碳库及碳库管理指数的影响

分析了长期不同施肥制度对潮棕壤活性碳库及碳库管理指数的影响。结果表明:长期施肥不同施肥制度对土壤活性碳库、碳素有效率及碳库管理指数有很大影响,长期施用有机循环肥处理,尤其是循环肥配合均衡化肥(NPK+O)施用处理的土壤有机碳、易氧化碳(ROC)、溶解性有机碳(DOC)、微生物量碳含量(MBC)、土壤碳素有效率及土壤碳库管理指数明显高于对照处理的土壤。潮棕壤活性碳库中不同形态的碳素含量大小顺序为:CROC>CMBC>CDOC,同一施肥处理水平下,不同形态碳素有效率以ACC>ABC>AAC。相关分析表明:土壤碳素有效率和碳库管理指数与土壤的化学性质尤其是土壤养分因子呈显著或极显著相关,反应了农业生产措施对土壤碳库的影响,运用土壤碳库管理指数可以很好地反映出土壤碳库的动态变化。

Electrochemical reactions of cyanocobalamin in acidic media

Electrochemical reactions of cyanocobalamin, CN-Cbl[Co(III)], were studied at glassy carbon electrodes in acidic media by means of cyclic voltammetry and differential pulse polarography. It was found that in pH 0 solution, CN-Cbl[Co(III)] exists mainly in the base-off form, {CN-Cbl[Co(III)]}(base-off). It can undergo a one-electron reduction and a follow-up chemical reaction to form {H2O-Cbl[Co(II)]}(base-off). The rate-constant k of the follow-up decyanation reaction is 0.022 s(-1). {H2O-Cbl[Co(II)]}(base-off) is further reduced to obtain H2O-Cbl[Co(I)]. (C) 1997 Elsevier Science S.A.

Electrochemical studies on vitamin B-12 and its derivatives

The electrochemical studies on vitamin B-12 and its derivatives were reviewed in this paper. The importance of electrochemical studies for explaining the mechanism of B-12 coenzyme in body was discussed. The latest results of electrochemical studies on vitamin B-12 and its derivatives was reviewed. A prospect for the electrochemical studies in vitamin B-12 and its derivatives was suggested.

Regulation of autoinducer 2 production and luxS expression in a pathogenic Edwardsiella tarda strain

Edwardsiella tarda is a bacterial pathogen that can infect both humans and animals. TX1, an Ed. tarda strain isolated from diseased fish, was found to produce autoinducer 2 (Al-2)-like activity that was growth phase dependent and modulated by growth conditions. The gene coding for the Al-2 synthase was cloned from TX1 and designated luxS(Et). LuxS(Et) was able to complement the Al-2 mutant phenotype of Escherichia coli strain DH5 alpha. Expression Of luxS(Et) correlated with Al-2 activity and was increased by glucose and decreased by elevated temperature. The effect of glucose was shown to be mediated through the cAMP-CRP complex, which repressed luxS(Et) expression. Overexpression of luxS(Et) enhanced Al-2 activity in TX1, whereas disruption of luxS(Et) expression by antisense RNA interference (i) reduced the level of Al-2 activity, (ii) impaired bacterial growth under various conditions, (iii) weakened the expression of genes associated with the type III secretion system and biofilm formation, and (iv) attenuated bacterial virulence. Addition of exogenous Al-2 was able to complement the deficiencies in the expression of TTSS genes and biofilm production but failed to rescue the growth defects. Our results (i) demonstrated that the Al-2 activity in TX1 is controlled at least in part at the level of luxS(Et) expression, which in turn is regulated by growth conditions, and that the temporal expression of luxS(Et) is essential for optimal bacterial infection and survival; and (ii) suggested the existence in Ed. tarda of a LuxS/Al-2-mediated signal transduction pathway that regulates the production of virulence-associated elements.

Regulation of autoinducer 2 production and luxS expression in a pathogenic Edwardsiella tarda strain

Edwardsiella tarda is a bacterial pathogen that can infect both humans and animals. TX1, an Ed. tarda strain isolated from diseased fish, was found to produce autoinducer 2 (Al-2)-like activity that was growth phase dependent and modulated by growth conditions. The gene coding for the Al-2 synthase was cloned from TX1 and designated luxS(Et). LuxS(Et) was able to complement the Al-2 mutant phenotype of Escherichia coli strain DH5 alpha. Expression Of luxS(Et) correlated with Al-2 activity and was increased by glucose and decreased by elevated temperature. The effect of glucose was shown to be mediated through the cAMP-CRP complex, which repressed luxS(Et) expression. Overexpression of luxS(Et) enhanced Al-2 activity in TX1, whereas disruption of luxS(Et) expression by antisense RNA interference (i) reduced the level of Al-2 activity, (ii) impaired bacterial growth under various conditions, (iii) weakened the expression of genes associated with the type III secretion system and biofilm formation, and (iv) attenuated bacterial virulence. Addition of exogenous Al-2 was able to complement the deficiencies in the expression of TTSS genes and biofilm production but failed to rescue the growth defects. Our results (i) demonstrated that the Al-2 activity in TX1 is controlled at least in part at the level of luxS(Et) expression, which in turn is regulated by growth conditions, and that the temporal expression of luxS(Et) is essential for optimal bacterial infection and survival; and (ii) suggested the existence in Ed. tarda of a LuxS/Al-2-mediated signal transduction pathway that regulates the production of virulence-associated elements.

Comparative proteomic profiles of the hepatopancreas in Fenneropenaeus chinensis response to hypoxic stress

Hypoxia, as one suboptimal environmental condition, can affect the physiological state of shrimp during pond aquaculture. To better understand the mechanism of response to hypoxic stress in Chinese shrimp Fenneropenaeus chinensis, proteome research approach was utilized. Differentially expressed proteins of hepatopancreas in adult Chinese shrimp between the control and hypoxia-stressed groups were screened. By 2-DE analysis, 67 spots showed obvious changes after hypoxia. Using LC-ESI-MS/MS, 51 spots representing 33 proteins were identified including preamylase, arginine kinase, phosphopyruvate hydratase, citrate synthase, ATP synthase alpha subunit, chymotrypsin BI, chitinase, ferritin, C-type lectin receptors, transketolase, formylglutathione hydrolase, formyltetrahydrofolate dehydrogenase, aldehyde dehydrogenase, glutathione peroxidase, cytosolic manganese superoxide dismutase, protein disulfide isomerase, beta-actin, oncoprotem nm23, crustacyanin-Cl and so on. These proteins could be functionally classified into several groups such as proteins related to energy production, metabolism-related proteins, immune-related proteins, antioxidant proteins, chaperones, cytoskeleton proteins and ungrouped proteins. The transcription levels of ten selected genes encode the identified proteins were analyzed by real-time PCR at different sampling times of hypoxia. This study is the first analysis of differentially expressed proteins in the hepatopancreas of shrimp after hypoxia and provides a new insight for further study in hypoxic stress response of shrimp at the protein level.