酸中毒条件下脓毒性休克大鼠胸主动脉对多巴胺反应性的变化

目的:观察不同酸中毒条件下正常大鼠和脓毒性休克大鼠胸主动脉对多巴胺反应性的变化。方法:采用离体血管灌流方法,观察对照组和脓毒性休克组大鼠胸主动脉在不同pH条件下的反应性变化。结果:pH值依次降低,对照组及脓毒性休克组离体胸主动脉对多巴胺反应性均下降,在相同pH值条件下脓毒性休克组比对照组离体血管对多巴胺反应性下降更为明显。结论:①环境pH值的下降会导致正常大鼠和脓毒性休克大鼠离体动脉对多巴胺反应性的下降。②在相同的酸性环境中脓毒性休克大鼠的血管对多巴胺刺激的反应性更差,更易失去活性。     

胍丁胺对离体大鼠主动脉张力的影响及其受体机制

采用离体血管环灌流方法,观察了胍丁胺（agmatine,Agm)对大鼠胸主动脉张力的影响,并探讨其受体机制,实验结果如下：（1）在苯肾上腺素PE,10^-6mol/L)引起血管预收缩的 基础上,Agm(10^-7-10^-2mol/L)剂量依赖性地舒张大鼠胸主动脉。（2）上述舒张反应在去除内皮和应用NOS抑制剂N^-G-mnitro-L-arginine methyl ester(L-NAME,0.5mmol/L)后依然存在,提示Agm的舒血管作用为非内皮依赖性,并无NO的参与。（3）在高Ca^2 (3mmol/L)引起血管预收缩的基础上,Agm也可剂量依赖性地舒张大鼠主动脉。（4）预先应用α2－肾上腺素能受体（α2－adrenergic receptor,α2－AR）和咪唑啉受体（IR）阻断剂idazoxan(10^-4mol/L)则可完全阻断Agm的上述作用。（5）应用α2－AR拮抗剂yohimbine(10^-4mol/L)可部分阻断Agm对大鼠主动脉的舒张反应,以上结果表明,Agm对大鼠主动脉血管的舒张作用是由α2－AR和IR共同介导。     

葛根素对抗高糖诱导的血管低反应性的作用及其机制

目的：研究葛根素是否可对抗高糖引起的血管低反应性,并探讨其作用机制。方法：采用血管环离体灌流装置,观察SD大鼠胸主动脉环的收缩反应;测定主动脉胆红素生成量反映血红素加氧酶-1（heme oxygenase-1,HO-1）的活性。结果：①与空白对照组（含11 mmol/L葡萄糖）相比,经44 mmol/L葡萄糖（高糖）孵育血管4 h后,主动脉环对苯肾上腺素（PE）引起的血管收缩反应下降;且该作用通过内皮依赖性途径实现。②葛根素（10-10~10-8mol/L）与高糖联合孵育,可剂量依赖性地改善高糖诱导的血管PE收缩反应的下降。③葛根素孵育血管后可引起血管HO-1活性增高;用ZnPP抑制HO-1的活性后,葛根素抗高糖损伤的作用被取消。结论：葛根素具有对抗高糖引起的血管收缩功能下降的作用,其机制可能是通过诱导HO-1活性增加实现的。     

NO—样松弛因子对止血带休克大鼠血管舒缩活动的影响

本工作在大鼠止血带休克（ＴｏＳ）模型上观察ＮＯ前体Ｌ－精氨酸Ｌ－Ａｒｇ,ＮＯ合成阻断剂Ｌ－ＮＮＡ及可溶性鸟苷酸环化酶抑制剂亚甲兰（ＭＢ）对离体胸主动脉舒缩活动的影响。发现止血带休克大鼠离体灌流的主动脉对去甲肾上腺素的反应性降低。血管组织ｃＧＭＰ含量增加。Ｌ－Ａｒｇ可增强这一变化,而Ｌ－ＮＮＡ或ＭＢ可减轻上述变化,而且这些药物作用不受血管内皮是否存在的影响。实验结果提示,非内皮细胞源的ＮＯ－样松弛因子（ＮＯ－ＬＲＦ）是引起止血带休克动物血管低反应性的因素之一     

青藤碱对家兔主动脉血管平滑肌细胞内游离钙浓度及蛋白激酶C的影响

观测青藤碱对培养家兔血管平滑肌细胞内游离钙浓度及正常和缺血缺氧刺激下蛋白激酶C（PKC）活性的影响。方法：Fura-2／AM作Ca^2＋指示剂,检测青藤碱对培养家兔主动脉血管平滑肌细胞静息Ca^2＋浓度及去甲肾上腺素,高K^＋,咖啡因刺激作用下的改变,并与钙拮抗剂维拉帕米进行对照研究;复制血管平滑肌细胞缺血缺氧模型,液闪仪测定PKC活性。结果：青藤碱剂量依赖性抑制高K^＋去极化引起[Ca^2＋]i升高,青藤碱10×10^-6mol.L^-1、3×10^-5mol.L^-1、10^-4mol.L^-1,对NE通过受体介导引起的[Ca^2＋]i增高也有明显抑制。但对静息状态下及咖啡因刺激的血管平滑肌细胞[Ca^2＋]i无明显影响。正常时,青藤碱处理后血管平滑肌细胞胞浆、胞膜PKC活性均升高;缺血缺氧状态下,胞浆PKC活性升高,但胞膜PKC活性降低,青藤碱处理后胞浆PKC活性下降,胞膜PKC活性上升。结论：青藤碱可能抑制血管平滑肌细胞电压依赖性钙通道和受体操纵性钙通道,降低细胞内游离钙水平。调节缺血缺氧条件下血管平滑肌细胞PKC活性。     

L—arg斤LNNA对大鼠胸主动脉内皮损伤后舒缩反应及cGMP…

本研究在大鼠胸主动脉内皮损伤内膜增生模型上观察了Ｌ－ａｒｇ和ＬＮＮＡ对大鼠胸主动脉条的血管反应性及ｃＧＭＰ含量的影响。血管反应性观察及血管局部ｃＧＭＰ测定发现,大鼠胸主动脉内皮损伤后３天对－ａｒｇ及ＬＮＮＡ的舒缩反应明显受损,血管局部基础ｃＧＭＰ明显下降,用Ｌ－ａｒｇ和ＬＮＮＡ干预后的ｃＧＭＰ变化亦明显受损,损伤后１０天以上现象明显恢复,损伤后２１天进一步恢复,但仍不能恢复正常。结果表明,内皮损伤     

褪黑素改善内毒素血症大鼠血管反应性

观察褪黑素(melatonin,MT)对脂多糖(lipopolysaccharide,LPS)诱导的体循环和肺循环血管反应性失调的影响,并探讨可能的作用机制。实验分为溶剂对照组、LPS组、LPS+MT组和MT组。制备离体胸主动脉环和肺动脉环,应用血管张力检测技术检测各组血管环对苯肾上腺素(phenylephrine,PE)和乙酰胆碱(acetylcholine,ACh)的反应性并绘制累积剂量反应曲线;制备各组血管组织匀浆,测定丙二醛(malondialhyde,MDA)和超氧化物歧化酶(superoxidedismutes,SOD)含量变化。结果显示:与对照组相比,LPS6h后胸主动脉对PE的收缩反应减弱(P<0.01),对PE(1×10–8~1×10–5mol/L)累积剂量反应曲线下移;而肺动脉对ACh的舒张反应显著下降(P<0.01),对ACh(1×10–8~1×10–5mol/L)累积剂量反应曲线下移。加用MT可显著改善LPS诱导的胸主动脉对缩血管剂PE的低反应性,同时可逆转LPS对肺动脉舒张反应的抑制,LPS+MT组胸主动脉对PE的累积剂量反应曲线和肺动脉对ACh的累积剂量反应曲线位于对照组和LPS组之间;MT还可对抗LPS导致的脂质过氧化,使MDA含量减少,提高抗氧化酶SOD的活性。上述结果提示,MT可改善内毒素血症大鼠的血管反应性失调,抗氧化途径可能是其发挥保护作用的机制之一。     

NOS抑制剂对CLP败血症休克大鼠血流动力学及血管张力变化的影响

目的:探讨三种一氧化氮合酶抑制剂(NOSI)对盲肠结扎和穿孔法(CLP)败血症休克血流动力学改变及血管张力变化的影响.方法:采用CLP建立大鼠败血症休克模型,腹腔注射三种NOSI对CLP败血症休克进行干预;在体颈动脉插管和心室内导管术,测定血压和左心室动力学指标;用离体血管灌流方法,测定大鼠胸主动脉环的张力.结果:分别用三种NOSI可降低CLP败血症休克的死亡率,改善血压和左心室动力学指标;三种NOSI均能抑制CLP引起的去内皮主动脉环对苯肾上腺素(PE)和KCl的收缩反应性下降,并且iNOSI氨基胍(AMG)能够抑制CLP引起的去内皮主动脉环对细胞外钙的反应性降低;非选择性NOSI左旋硝基精氨酸甲酯(L-NAME)与nNOSI7-硝基吲唑(7-NI)均能抑制CLP引起的内皮完整主动脉环对苯肾上腺素(PE)和KCl的收缩反应性下降,但是三种NOSI均不能抑制CLP引起的内皮完整动脉环对细胞外钙的反应性降低.结论:三种NOSI均能改善CLP晚期败血症休克大鼠血流动力学和无内皮血管的收缩反应性,L-NAME和7-NI还可改善有内皮血管的收缩反应性.     

L-arg和LNNA对大鼠胸主动脉内皮损伤后舒缩反应及cGMP含量的影响

本研究在大鼠胸主动脉内皮损伤内膜增生模型上观察了Ｌ－ａｒｇ和ＬＮＮＡ对大鼠胸主动脉条的血管反应性及ｃＧＭＰ含量的影响。血管反应性观察及血管局部ｃＧＭＰ测定发现,大鼠胸主动脉内皮损伤后３天对－ａｒｇ及ＬＮＮＡ的舒缩反应明显受损,血管局部基础ｃＧＭＰ明显下降,用Ｌ－ａｒｇ和ＬＮＮＡ干预后的ｃＧＭＰ变化亦明显受损,损伤后１０天,以上现象明显恢复,损伤后２１天进一步恢复,但仍不能恢复正常。结果表明,内皮损伤后的动脉血管ＥＤＲＦ产生明显受损,且长期不能恢复正常。     

茉莉酸甲酯对水稻幼苗抗冷性的影响

测定茉莉酸甲酯（MJ）对冷胁迫条件下水稻幼苗生长和与抗冷性相关生理生化指标影响的结果表明：较高浓度的MJ（10^-3mol·L^-1）明显抑制冷胁迫下的水稻幼苗生长,增加细胞膜的渗透性;浓度低一些的MJ（10^-4、10^-5、10^-6、10^-7mol·L^-1）对冷胁迫下水稻幼苗的生长和细胞膜有不同程度的保护作用,其中以10～mol·L^-1MJ的效果为佳。10～mol·L^-1 MJ处理的叶中叶绿素降解程度小,可溶性糖、可溶性总蛋白和脯氨酸的含量以及超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）的活性均增加,丙二醛（MDA）含量降低,因而水稻幼苗的抗冷性提高。     

Vegetation Mapping of the Mond Protected Area of Bushehr Province （South-west Iran）

Arid regions of the world occupy up to 35% of the earth＇s surface, the basis of various definitions of climatic conditions, vegetation types or potential for food production. Due to their high ecological value, monitoring of arid regions is necessary and modern vegetation studies can help in the conservation and management of these areas. The use of remote sensing for mapping of desert vegetation is difficult due to mixing of the spectral reflectance of bright desert soils with the weak spectral response of sparse vegetation. We studied the vegetation types in the semiarid to arid region of Mond Protected Area, south-west Iran, based on unsupervised classification of the Spot XS bands and then produced updated maps. Sixteen map units covering 12 vegetation types were recognized in the area based on both field works and satellite mapping. Halocnemum strobilaceum and Suaeda fruticosa vegetation types were the dominant types and Ephedra foliata, Salicornia europaea-Suaeda heterophylla vegetation types were the smallest. Vegetation coverage decreased sharply with the increase in salinity towards the coastal areas of the Persian Gulf. The highest vegetation coverage belonged to the riparian vegetation along the Mond River, which represents the northern boundary of the protected area. The location of vegetation types was studied on the separate soil and habitat diversity maps of the study area, which helped in final refinements of the vegetation map produced.     

Oxygation Enhances Growth,Gas Exchange and Salt Tolerance of Vegetable Soybean and Cotton in a Saline Vertisol

Impacts of salinity become severe when the soil is deficient in oxygen. OxygaUon （using aerated water for subsurface drip irrigation of crop） could minimize the impact of salinity on plants under oxygen-limiting soil environments. Pot experiments were conducted to evaluate the effects of oxygation （12% air volume/volume of water） on vegetable soybean （moderately salt tolerant） and cotton （salt tolerant） in a salinized vertisol at 2, 8, 14, 20 dS/m ECe. In vegetable soybean, oxygation increased above ground biomass yield and water use efficiency （WUE） by 13% and 22%, respectively, compared with the control. Higher yield with oxygation was accompanied by greater plant height and stem diameter and reduced specific leaf area and leaf Na^＋ and CI^- concentrations. In cotton, oxygation increased lint yield and WUE by 18% and 16%, respectively, compared with the control, and was accompanied by greater canopy light interception, plant height and stem diameter. Oxygation also led to a greater rate of photosynthesis, higher relative water content in the leaf, reduced crop water stress index and lower leaf water potential. It did not, however, affect leaf Na^＋ or CI^- concentration. Oxygation invariably increased, whereas salinity reduced the K^＋： Na^＋ ratio in the leaves of both species. Oxygation improved yield and WUE performance of salt tolerant and moderately tolerant crops under saline soil environments, and this may have a significant impact for irrigated agriculture where saline soils pose constraints to crop production.     

Molecular Characterization of the Calvin Cycle Enzyme Phosphoribulokinase in the Stramenopile Alga Vaucheria litorea and the Plastid Hosting Mollusc Elysia chlorotica

Phosphoribulokinase （PRK）, a nuclear-encoded plastid-localized enzyme unique to the photosynthetic carbon reduction （Calvin） cycle, was cloned and characterized from the stramenopile alga Vaucheria litorea. This alga is the source of plastids for the mollusc （sea slug） Elysia chlorotica which enable the animal to survive for months solely by photoautotrophic CO2 fixation. The 1633-bp V. litorea prk gene was cloned and the coding region, found to be interrupted by four introns, encodes a 405-amino acid protein. This protein contains the typical bipartite target sequence expected of nuclearencoded proteins that are directed to complex （i.e. four membrane-bound） algal plastids. De novo synthesis of PRK and enzyme activity were detected in E. chlorotica in spite of having been starved of V. litorea for several months. Unlike the algal enzyme, PRK in the sea slug did not exhibit redox regulation. Two copies of partial PRK-encoding genes were isolated from both sea slug and aposymbiotic sea slug egg DNA using PCR. Each copy contains the nucleotide region spanning exon 1 and part of exon 2 of V litorea prk, including the bipartite targeting peptide. However, the larger prk fragment also includes intron 1. The exon and intron sequences of prk in E. chlorotica and V/itorea are nearly identical. These data suggest that PRK is differentially regulated in V. litorea and E. chlorotica and at least a portion of the V. litorea nuclear PRK gene is present in sea slugs that have been starved for several months.     

Identification,expression, and characterization of the highly conserved D-xylose isomerase in animals

D-xylose is a necessary sugar for animals. The xylanase from a mollusk, Ampullaria crossean, was previously reported by our laboratory. This xylanase can degrade the xylan into D-xylose. But there is still a gap in our knowledge on its metabolic pathway. The question is how does the xylose enter the pentose pathway？ With the help of genomic databases and bioinformatic tools, we found that some animals, such as bacteria, have a highly conserved D-xylose isomerase （EC 5.3.1.5）. The xyiose isomerase from a sea squirt, Ciona intestinali, was heterogeneously expressed in Escherichia coli and purified to confirm its function. The recombinant enzyme had good thermal stability in the presence of Mg^2＋. At the optimum temperature and optimum pH environment, its specific activity on D-xylose was 0.331 μmol/mg/min. This enzyme exists broadly in many animals, but it disappeared in the genome of Amphibia-like Xenopus laevis. Its sequence was highly conserved. The xylose isomerases from animals are very interesting proteins for the study of evolution.     

The Response Difference of Mitochondria in Recalcitrant Antiaris toxicaria Axes and Orthodox Zea mays Embryos to Dehydration Injury

Long-term preservation of recalcitrant seeds is very difficult because the physiological basis on their desiccation sensitivity is poorly understood. Survival of Antiaris toxicaria axes rapidly decreased and that of immature maize embryos very slowly decreased with dehydration. To understand their different responses to dehydration, we examined the changes in mitochondria activity during dehydration. Although activities of cytochrome （Cyt） c oxidase and malate dehydrogenase of the A. toxicaria axis and maize embryo mitochondria decreased with dehydration, the parameters of maize embryo mitochondria were much higher than those of A. toxicaria, showing that the damage was more severe for the A. toxicaria axis mitochondria than for those of maize embryo. The state I and III respiration of the A. toxicaria axis mitochondria were higher than those of maize embryo, the former rapidly decreased, and the latter slowly decreased with dehydration. The proportion of Cyt c pathway to state III respiration for the A. toxicaria axis mitochondria was low and rapidly decreased with dehydration, and the proportion of alternative oxidase pathway was high and slightly increased with dehydration. In contrast, the proportion of Cyt c pathway for maize embryo mitochondria was high, and that of alternative oxidase pathway was low. Both pathways decreased slowly with dehydration.     

Chloroplast Proteomics and the Compartmentation of Plastidial Isoprenoid Biosynthetic Pathways

Recent advances in the proteomic field have allowed high-throughput experiments to be conducted on chloroplast samples. Many proteomic investigations have focused on either whole chloroplast or sub-plastidial fractions. To date, the Plant Protein Database （PPDB, Sun et al., 2009） presents the most exhaustive chloroplast proteome available online. However, the accurate localization of many proteins that were identified in different sub-plastidial compartments remains hypothetical. Ferro et al. （2009） went a step further into the knowledge of Arabidopsis thaliana chloroplast proteins with regards to their accurate localization within the chloroplast by using a semi-quantitative proteomic approach known as spectral counting. Their proteomic strategy was based on the accurate mass and time tags （AMT） database approach and they built up AT_CHLORO, a comprehensive chloroplast proteome database with sub-plastidial localization and curated information on envelope proteins. Comparing these two extensive databases, we focus here on about 100 enzymes involved in the synthesis of chloroplast-specific isoprenoids. Well known pathways （i.e. compartmentation of the methyl erythritol phosphate biosynthetic pathway, of tetrapyrroles and chlorophyll biosynthesis and breakdown within chloroplasts） validate the spectral counting-based strategy. The same strategy was then used to identify the precise localization of the biosynthesis of carotenoids and prenylquinones within chloroplasts （i.e. in envelope membranes, stroma, and/or thylakoids） that remains unclear until now.     

The Translational Apparatus of Plastids and Its Role in Plant Development

Chloroplasts （plastids） possess a genome and their own machinery to express it. Translation in plastids occurs on bacterial-type 70S ribosomes utilizing a set of tRNAs that is entirely encoded in the plastid genome. In recent years, the components of the chloroplast translational apparatus have been intensely studied by proteomic approaches and by reverse genetics in the model systems tobacco （plastid-encoded components） and Arabidopsis （nucleus-encoded components）. This work has provided important new insights into the structure, function, and biogenesis of chloroplast ribosomes, and also has shed fresh light on the molecular mechanisms of the translation process in plastids. In addition, mutants affected in plastid translation have yielded strong genetic evidence for chloroplast genes and gene products influencing plant develop- ment at various levels, presumably via retrograde signaling pathway（s）. In this review, we describe recent progress with the functional analysis of components of the chloroplast translational machinery and discuss the currently available evidence that supports a significant impact of plastid translational activity on plant anatomy and morphology.     

Response of Chinese Wampee Axes and Maize Embryos to Dehydration at Different Rates

Survival of wampee （Clausena lansium Skeels） axes and maize （Zea mays L.） embryos decreased with rapid and slow dehydration. Damage of wampee axes by rapid dehydration was much less than by slow dehydration, and that was contrary to maize embryos. The malondialdehyde contents of wampee axes and maize embryos rapidly increased with dehydration, those of wampee axes were lower during rapid dehydration than during slow dehydration, and those of maize embryos were higher during rapid dehydration than during slow dehydration. Activities of superoxide dismutase （SOD）, ascorbate peroxidase （APX） and catalase （CAT） of wampee axes markedly increased during the early phase of dehydration, and then rapidly decreased, and those of rapidly dehydrated axes were higher than those of slow dehydrated axes when they were dehydrated to low water contents. Activities of SOD and APX of maize embryos notable decreased with dehydration. There were higher SOD activities and lower APX activities of slowly dehydrated maize embryos compared with rapidly dehydrated maize embryos. CAT activities of maize embryos markedly increased during the early phase of dehydration, and then decreased, and those of slowly dehydrated embryos were higher than those of rapidly dehydrated embryos during the late phase of dehydration.     

Induction of the AOX1D Isoform of Alternative Oxidase in A. thaliana T-DNA Insertion Lines Lacking Isoform AOX1A Is Insufficient to Optimize Photosynthesis when Treated with Antimycin A

Plant respiration is characterized by two pathways for electron transfer to O2, namely the cytochrome pathway （CP） that is linked to ATP production, and the alternative pathway （AP）, where electrons from ubiquinol are directly transferred to O2 via an alternative oxidase （AOX） without concomitant ATP production. This latter pathway is well suited to dispose of excess electrons in the light, leading to optimized photosynthetic performance. We have characterized T- DNA-insertion mutant lines of Arabidopsis thaliana that do not express the major isoform, AOXIA. In standard growth conditions, these plants did not show any phenotype, but restriction of electron flow through CP by antimycin A, which induces AOXIA expression in the wild-type, led to an increased expression of AOXID in leaves of the aoxla-knockout mutant. Despite the increased presence of the AOX1D isoform in the mutant, antimycin A caused inhibition of photosyn- thesis, increased ROS, and ultimately resulted in amplified membrane leakage and necrosis when compared to the wild- type, which was only marginally affected by the inhibitor. It thus appears that AOX1 D was unable to fully compensate for the loss of AOXIA when electron flow via the CP is restricted. A combination of inhibition studies, coupled to metabolite profiling and targeted expression analysis of the P-protein of glycine decarboxylase complex （GDC）, suggests that the aoxla mutants attempt to increase their capacity for photorespiration. However, given their deficiency, it is intriguing that increase in expression neither of AOX1D nor of GDC could fully compensate for the lack of AOXIA to optimize pho- tosynthesis when treated with antimycin A. We suggest that the aoxla mutants can further be used to substantiate the current models concerning the influence of mitochondrial redox on photosynthetic performance and gene expression.