环境胁迫对对虾免疫系统的影响研究

环境胁迫（environmental stress）是指环境对生物所处的生存状态产生的压力，分为急性环境胁迫和慢性环境胁迫。捕捞、干扰、水质的突变等可以引起急性环境胁迫，而水质逐渐恶化和高密度放养等会造成慢性胁迫。近年来随着人类活动范围的不断扩大和程度的加深，环境资源受到了很大的破坏，养殖对虾受到的环境胁迫日益严重。这些胁迫可使对虾产生应激反应，虽然这是一种保护性反应，但持续处于应激状态，机体的免疫防御体系的功能会受到抑制，就会影响到其抗病力。当前对虾的病害越来越严重，大规模的死亡已经成为制约养殖业发展的瓶颈。     

盐胁迫对苗期湖南稷子K+、Na+含量与分布的影响

以湖南稷子(Echinochloa frumentacea)为材料,设置不同浓度(0、25、50、75、100、125、150、200 mmol·L-1)的NaCl和Na2 SO4作为胁迫处理,探讨盐胁迫对湖南稷子苗期K+、Na+吸收与分布特性的影响.结果表明,随着NaCl和Na2 SO4浓度的增加,湖南稷子叶片、茎鞘...     

大学生就业倦怠的评测与化解

就业倦怠是大学生就业过程中新出现的、尚未引起足够重视的一种现象,是由内在的反复心理挫折体验而形成的外显消极行为,其主要表现为情感耗竭、人格解体和个人成就感降低。通过借用马诗勒倦怠问卷,可以对其进行测量和诊断。为了化解就业倦怠,应在增强抗挫折能力的基础上,致力于减少大学生对就业岗位的情感损耗,保证目标岗位与心理期待的始终一致性,提高就业过程中的成就感,并适当进行压力管理和训练。     

Organic Acid Effects on Nutrient Uptake by Rice

The purpose of this work was to evaluate the responses of 20 rice cultivars to the phytotoxic effects of acetic, propionic, and butyric acids produced in soils under anaerobic conditions. The study was conducted in a hydroponic system, with four levels (0, 3, 6, and 9 mM) of the three organic acids in the ratio of 6:3:1 in a factorial of complete randomized block design with three replications. The evaluated variables were phosphorus (P) and potassium (K) contents. The analysis of variance revealed a significant interaction, and the established regressions showed differences among the genotypes as evaluated for both variables. Four genotypes were classified as tolerant in relation to P content and three genotypes as tolerant in relation to K. The best performance was verified with japonica genotypes and the irrigation-based growing system.     

Astaxanthin from Haematococcus pluvialis Prevents Oxidative Stress on Human Endothelial Cells without Toxicity

Astaxanthin, a powerful antioxidant, is a good candidate for the prevention of intracellular oxidative stress. The aim of the study was to compare the antioxidant activity of astaxanthin present in two natural extracts from Haematococcus pluvialis, a microalgae strain, with that of synthetic astaxanthin. Natural extracts were obtained either by solvent or supercritical extraction methods. UV, HPLC-DAD and (HPLC-(atmospheric pressure chemical ionization (APCI)+)/ion trap-MS) characterizations of both natural extracts showed similar compositions of carotenoids, but different percentages in free astaxanthin and its ester derivatives. The Trolox equivalent antioxidant capacity (TEAC) assay showed that natural extracts containing esters displayed stronger antioxidant activities than free astaxanthin. Their antioxidant capacities to inhibit intracellular oxidative stress were then evaluated on HUVEC cells. The intracellular antioxidant activity in natural extracts was approximately 90-times higher than synthetic astaxanthin (5 µM). No modification, neither in the morphology nor in the viability, of vascular human cells was observed by in vitro biocompatibility study up to 10 µM astaxanthin concentrations. Therefore, these results revealed the therapeutic potential of the natural extracts in vascular human cell protection against oxidative stress without toxicity, which could be exploited in prevention and/or treatment of cardiovascular diseases.     

Main stem movement of Atlantic salmon parr in response to high river temperature

Atlantic salmon become thermally stressed when water temperatures exceed 23 °C. To alleviate this stress, they behaviourally thermoregulate by moving to patches of cold water, often forming large aggregations. These patches are known as thermal refuges. Given the consensus that climate change will increase temperatures in Atlantic salmon catchments, thermal refuges will become increasingly important in minimising summer mortalities. While the behaviour of salmonids within thermal refuges is fairly well understood, less is known about their main stem movement in search of thermal refuges or its thermal and temporal cues. We detail the results of a PIT telemetry study to investigate the main stem movement behaviour of thermally stressed Atlantic salmon parr in a temperature‐impacted river. PIT antennas placed around two thermal refuges and at the upstream and downstream limits of their surrounding reach were used to record the movement of salmonids during a heatwave. We observed parr movement at the upstream and downstream antennas 135 min prior to the occurrence of the midpoint of aggregations in the thermal refuges, indicating that Atlantic salmon parr make reach‐scale movements in search of cool water prior to aggregating. Logistic regression showed that the number of degree hours >28 °C predicted the occurrence of main stem movement with a good degree of accuracy, indicating that this temperature represents a fundamental threshold causing Atlantic salmon parr to move towards cool water. Such data could be instrumental in allowing river managers to place limits on human activity within rivers, allowing salmon populations time to recover following heat stress events.     

实时定量PCR检测逆境下盐芥ABI1基因表达水平

运用实时定量PCR的方法对盐芥ABI1基因在干旱、ABA、冷和盐胁迫下的表达情况进行了检测,并对ABI1在耐盐植物中的抗逆能力进行了分析,为粮食作物的耐逆性改良奠定基础。     

生物炭表面水溶活性分子可以有效提高水稻的耐旱性

生物炭是一种可以改良土壤、增强作物产量和提升作物品质的新型农林废弃物再利用材料。本研究通过振荡方式制备生物炭浸提液,利用水培系统培养水稻幼苗,以20%PEG6000、300 mmol/L和500 mmol/L甘露醇模拟干旱胁迫,研究生物炭表面水溶活性分子对水稻幼苗抗旱性的影响。研究结果发现:生物炭浸提液可有效缓解干旱胁迫造成的水稻种子萌发和幼苗生长抑制,缓解叶绿素含量、鲜重及存活率的降低,同时可以降低体内的活性氧积累等。实时定量RT-PCR检测表明生物炭浸提液促进干旱胁迫响应标志基因的表达量。研究结果说明生物炭浸提液可以提高干旱胁迫下水稻幼苗的抗氧化能力,进一步提高水稻幼苗对干旱胁迫的耐受性。     

用最大熵法进行沥青路面工程实例的结构可靠性分析

结合工程实例以蒙特卡罗分析法为基本出发点,首先通过计算机根据弯沉和弯拉应力的功能函数来生成1000个功能函数的一个随机抽样,然后用大熵法拟合沥青路面的弯沉功能函数的密度函数,求出两种失效模式的失效概率。同时,把整个路段看作是一个由弯沉失效和弯拉应力失效的两种失效模式串联组成的网络系统,对整个系统进行了可靠性评估。     

Exogenous Nitric Oxide Involved in Subcellular Distribution and Chemical Forms of Cu~（2＋） Under Copper Stress in Tomato Seedlings

Nitric oxide（NO）,a bioactive signaling molecule,serves as an antioxidant and anti-stress agent under abiotic stress.A hydroponics experiment was conducted to investigate the effects of sodium nitroprusside（SNP）,a NO donor,on tomato seedlings exposed to 50 μmol L-1CuCl 2.The results show that copper is primarily stored in the soluble cell sap fraction in the roots,especially after treatment with Cu＋SNP treatment,which accounted for 66.2% of the total copper content.The copper concentration gradually decreased from the roots to the leaves.In the leaves,exogenous NO induces the storage of excess copper in the cell walls.Copper stress decreases the proportion of copper integrated with pectates and proteins,but exogenous NO remarkably reverses this trend.The alleviating effect of NO is blocked by hemoglobin.Thus,exogenous NO is likely involved in the regulation of the subcellular copper concentrations and its chemical forms under copper stress.Although exogenous NO inhibited the absorption and transport of excess copper to some extent,the copper accumulation in tomato seedlings significantly increased under copper stress.The use of exogenous NO to enhance copper tolerance in some plants is a promising method for copper remediation.