Tolerance of soil algae and cyanobacteria to drought stress

Tolerance to drought stress in soil crust microorganisms is essential for exploiting suitable organisms for restoring soil. In this study, the responses to drought stress of two drought‐tolerant species, a green alga and a cyanobacterium, were compared with those of two non‐tolerant green algae. In response to drought stress, induced by treatment with polyethylene glycol, the intracellular proline levels increased and were associated with increases in malondialdehye, pigment contents, and enzyme activities such as superoxide dismutase (SOD) and peroxidase (POD). Our results suggest that tolerance to drought stress could be indicated by the intracellular levels of proline, SOD, and carotenoids. This study provides insights into the drought physiology of the photosynthetic microorganisms and suggests that Leptolyngbya boryana and Chlorella vulgaris are suitable pioneer organisms for soil restoration.     

NaCl胁迫对藜麦幼苗生长及生理特性的影响

为探讨盐胁迫下两类不同地区藜麦品种幼苗的耐盐机制,该文利用不同浓度的NaCl溶液,对来自青海省海东市乐都区的'LD-13'(低盐地区)和来自青海省海西州乌兰县的'WL-192'(高盐地区)的2个藜麦品种的种子和幼苗进行盐胁迫处理,研究了种子萌发指标(发芽率、发芽势、发芽指数),生长指标(鲜重、根长、茎长)及生理指标(M...     

不同生态型芦苇种群对盐胁迫的生长和光合特性

土壤盐渍化是影响我国土壤利用效率的主要因素之一,芦苇是改良土壤盐渍化的良好实验材料,但芦苇有着多种的生态型,比较各生态型芦苇的耐盐差异成为亟待解决的问题。通过设置淡水(0.00%)与加盐(质量浓度2.00%)处理控制实验,测量芦苇的生长指标和光合指标,比较河口型芦苇与内陆型芦苇耐盐性,寻找合适生态型的芦苇作为改良土壤盐渍化的生物材料。在实验中,与淡水条件相比,加盐(2.00%)处理条件下,河口型芦苇和内陆型芦苇的株高(height)、蒸腾速率(E)均显著性下降,但是两种生态型的芦苇的水分利用效率(WUE)明显提高;河口型的芦苇相对生长速率(RGR)和气孔导度(Gs)都明显高于内陆型芦苇。在淡水环境中,河口型芦苇的相对生长速率(RGR)和净光合速率(A)都显著性地高于内陆型芦苇。结果表明两种生态型的芦苇在进化过程中存在一定程度上的分化,盐胁迫会抑制两种芦苇的生长,两种生态型芦苇的相对生长速率和气孔导度在盐胁迫下出现明显地差异,表明两种生态型的芦苇对盐度的响应机制有所差异。相比于内陆型芦苇,河口型芦苇有着更强的耐盐性,内陆型及河口型芦苇的表型性状差异主要是由于其原生境的差异所决定的。     

基于光合系统参数建立马铃薯耐荫性综合评价体系

为构建便捷的马铃薯(Solanum tuberosum)耐荫性综合评价体系并发掘耐荫种质, 以35个马铃薯品种(系)为实验材料, 测定块茎膨大期遮荫下植株叶片叶绿素含量、光合能力和叶绿素荧光等光合参数及收获后块茎单株产量和淀粉含量等指标。根据耐荫系数, 利用主成分分析法、隶属函数法、聚类分析法和逐步回归分析法进行综合评价。通过主成分分析将马铃薯耐荫性相关的13个单项光合指标转换为6个综合指标, 代表了全部信息的87.51%。以此计算各种质的隶属函数值, 并以主成分的贡献率进行加权, 最终获得所用材料耐荫性的综合评价值(D值)。根据D值聚类分析结果将35个马铃薯分为4类, 其中Eshu10和Lishu6分别为耐荫性最强和最弱的品种。通过逐步回归分析建立了马铃薯耐荫性评价数学模型: D=0.060+0.106G_s+0.214qP+0.143NPQ。同时, 用该评价体系鉴定为耐荫性强的品种(系)在遮荫后其产量和/或淀粉含量等指标减幅均低于耐荫性弱的种质, 表明该评价体系可用于快速评价和预测马铃薯种质的耐荫性。     

Genetic variation for tolerance to acidic water in salmonids

Water pH is an important factor affecting the general water quality as well as quality traits in fishes, and the magnitude of the effect varies among species. The massive and negative effect of acidification of rivers and lakes became evident during the 1960s and 1970s and caused the depletion of fish stocks in several countries in the northern hemisphere. Significant variation in tolerance to acidic water has been documented among salmonid species, and large genetic variation has been identified among strains of brown trout Salmo trutta, brook trout Salvelinus fontinalis and Atlantic salmon Salmo salar. For S. trutta, S. fontinalis and S. salar, there is considerable additive genetic variation in tolerance to acidic water, with heritabilities (h(2)) ranging from 0·09 to 0·27 for dead eyed-eggs (the period most sensitive to low pH). The main reasons for depletion of freshwater fish stocks are discussed.     

Benzylideneoxymorphone: A new lead for development of bifunctional mu/delta opioid receptor ligands

Opioid analgesic tolerance remains a considerable drawback to chronic pain management. The finding that concomitant administration of delta opioid receptor (DOR) antagonists attenuates the development of tolerance to mu opioid receptor (MOR) agonists has led to interest in producing bifunctional MOR agonist/DOR antagonist ligands. Herein, we present 7-benzylideneoxymorphone (6, UMB 246) displaying MOR partial agonist/DOR antagonist activity, representing a new lead for designing bifunctional MOR/DOR ligands.     

Do ice nucleating lipoproteins protect frozen insects against toxic chemical agents?

As the body fluid of freeze-tolerant organisms freezes, solutes become concentrated in the gradually smaller unfrozen fluid fraction, and dissolved trace metals may reach toxic levels. A dialysis technique was used to investigate the metal binding capacity of the low density fraction of the hemolymph from the freeze tolerant beetle Phyto depressus. The low density fraction, assumed to contain the ice nucleating lipoproteins, showed approximately 100 times greater capacity to bind metals (Cd ²⁺, Cu ²⁺ and Zn ²⁺) than the proteins albumin, hemoglobin and similar to metallothionein. The high metal binding capacity in the low density fraction raises the question if the ice nucleating lipoproteins might assist in detoxification of potentially toxic concentrations of metals that may occur when a large fraction of the bodyfluids of freeze tolerant insects freeze. This hypotheis is consistent with the fact that the lipoprotein ice nucleators are present in far greater amounts than required for ice nucleation, and also with the fact that the lipoprotein ice nucleators have a remarkably high content of amino acids with negatively charged residues that may act as metal binding sites.     

外源H2O2对小麦幼苗耐盐性的调节作用

以高原448小麦品种为材料,分别测定了4个处理(Hoagland营养液、Hoagland营养液 150 mmol/LNaCl、Hoagland营养液 150 mmol/L NaCl 10μmol/L H2O2和Hoagland营养液 10μmol/L H2O2)的小麦幼苗在第2、4、6、8天叶片叶绿素、丙二醛、可溶性糖和还原性谷胱甘肽含量.结果显示:外源H2O2提高了NaCl胁迫下4个时段小麦幼苗的叶绿素含量(8.27%、32.57%、10.19%、4.86%)及还原性谷胱甘肽含量(3.09%、23.97%、5.85%、2.11%),显著提高了可溶性糖含量(14.58%、8.43%、16.68%、5.8%,P<0.05),而显著降低了其丙二醛含量(17.53%、14.04%、4.75%、8.47%,P<0.05).外源H2O2(10μmol/L)使NaCl胁迫下叶绿素含量和还原性谷胱甘肽含量峰值提前,同时推迟了丙二醛峰值出现的时间.研究表明,外源H2O2通过提高叶片叶绿素、可溶性糖和还原性谷胱甘肽含量以有效地增强小麦幼苗的耐盐性.