水稻叶片对镉胁迫响应的蛋白质差异表达

为揭示水稻镉抗性的分子机理,以抗镉水稻品种P1312777和镉敏感水稻品种IR24为材料,在镉离子浓度为0(对照)、50和100 μmol·L-1条件下水培处理7 d,应用蛋白质组学方法分析了2种水稻叶片对镉胁迫响应的蛋白质差异表达.结果表明:镉胁迫下水稻PI312777叶片中共检测到差异表达蛋白质点31个,通过MALDI-TOF/MS分析,鉴定了其中的24个蛋白质(包括20个不同蛋白质,4个重复检出蛋白质);IR24叶片中共检测到差异表达蛋白质点19个,其中15个蛋白质得到鉴定.PI312777叶片鉴定出的20个蛋白质覆盖了IR24叶片鉴定的15个蛋白质,前者有4个与光合作用相关,11个与细胞防御代谢相关,3个与其他代谢相关,2个为功能未知蛋白.与对照相比,不同浓度镉胁迫下,抗镉水稻PI312777叶片中热激蛋白、谷胱甘肽还原酶、蛋白酶体α亚基6型、果糖1,6-二磷酸醛缩酶、硫氧还蛋白和DNA重组修复蛋白均上调表达;镉敏感水稻IR24叶片中热激蛋白、谷胱甘肽还原酶、蛋白酶体α亚基6型的表达无显著差异,果糖1,6-二磷酸醛缩酶和硫氧还蛋白则下调表达.此外,DNA重组修复蛋白仅在镉胁迫的PI312777叶片中表达.水稻PI312777比IR24具有更强的镉抗性与这些差异表达的蛋白质密切相关.     

抽穗扬花期高温胁迫对水稻主要品质指标的影响

高温热害对水稻生产造成了巨大的损失。利用国际水稻研究所耐热圃材料,在抽穗扬花期进行高温处理,研究了该时期高温胁迫对水稻主要品质评价指标的影响,结果如下：水稻耐热圃材料的耐热性有较大的差别,依然存在高温相对敏感材料;抽穗扬花期高温胁迫对水稻主要品质评价指标影响较大;高温胁迫对水稻籽粒的透明度、长宽比、垩白率、糊化温度和蛋白质含量等品质指标与品种的耐热性相关关系不大;高温胁迫下直链淀粉含量变化与品种耐热系数表现出显著的正相关关系（r=0.659 78）;高温胁迫下胶稠度变化与不同水稻品种的耐热系数呈显著的负相关关系（r=-0.516 70）。     

水稻生殖发育期耐热性的分子遗传机制研究进展北大核心CSCD

水稻在生殖发育期对高温胁迫非常敏感,高温热害已经成为水稻生产最重要的限制因子之一。阐明水稻在生殖发育期耐热性的分子遗传机制,挖掘耐热关键基因,利用基因工程以及分子标记辅助选择的方法改良水稻品种的耐热性具有重要意义。从水稻生殖发育期耐热性的数量性状基因定位(QTL)、转录以及蛋白水平的高温应答、耐热转基因研究领域的进展进行了概述。     

水稻生殖发育期耐热性的分子遗传机制研究进展

水稻在生殖发育期对高温胁迫非常敏感,高温热害已经成为水稻生产最重要的限制因子之一。阐明水稻在生殖发育期耐热性的分子遗传机制,挖掘耐热关键基因,利用基因工程以及分子标记辅助选择的方法改良水稻品种的耐热性具有重要意义。从水稻生殖发育期耐热性的数量性状基因定位(QTL)、转录以及蛋白水平的高温应答、耐热转基因研究领域的进展进行了概述。     

外源亚精胺对高温下黄瓜幼苗叶片抗氧化系统的影响

以黄瓜热敏感品种‘长春密刺'和耐热品种‘津春4号'为试材,在人工气候箱内采用营养液栽培法研究了外源亚精胺(Spd)预处理对短期高温胁迫(42℃)下黄瓜幼苗叶片抗氧化系统的影响.结果显示:(1)随高温胁迫时间的延长,2个黄瓜品种幼苗叶片相对电导率升高、MDA含量增加,热敏感品种的膜脂过氧化程度大于耐热品种;高温胁迫4h,SOD活性降低,POD、CAT、APX活性升高,抗坏血酸(AsA)含量升高,类胡萝卜素(Car)含量降低,且随胁迫时间反映出耐热品种抗氧化系统的自我调节能力大于热敏感品种.(2)外源Spd预处理能有效抑制高温胁迫引起的膜脂过氧化伤害,增强SOD、POD、APX活性以及AsA和Car含量,增强植株抗氧化能力,且在热敏感品种上的应用效果优于耐热品种.研究表明,外源Spd预处理能有效提高黄瓜幼苗叶片处于高温胁迫时的抗氧化能力,对缓解高温胁迫有重要作用.     

观赏山楂耐热性及其叶片光合与叶绿素荧光特性研究

以引自国内外的15种观赏山楂苗木为材料,于上海夏季自然高温下对其叶片光合气体交换参数及叶绿素荧光参数进行测定,并观察它们的田间耐热性,以揭示其耐热的光合生理机制.结果显示,4种山楂表现出较强耐热性,6种较耐热,而5种耐热性较差;15种山楂叶片净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)、瞬时水分利用效率(WUE)的种间差异显著(P<0.05),且耐热性强的品种P_n、T_r、G_s、WUE值较高,高温下能够维持较高的光合固碳水平;各品种山楂叶片的PSⅡ最大光能转换效率F_v/F_m、电子传递效率ΦPSⅡ和光能捕获效率F_v'/F_m'差异显著,耐热性强品种F_v/F_m保持在0.8以上,且ΦPSⅡ值与F_v'/F_m'较高.研究表明,观赏山楂主要通过加大气孔蒸腾散热、降低叶表面温度以及维持较高光能电子传递与转化效率来减轻高温对光合机构伤害,以维持植株正常光合作用;山楂叶片PSⅡ原初光能转换效率及潜在活性与其耐热性密切相关,F_v/F_m值可作为山楂耐热性鉴定指标.     

利用蛋白质组学技术揭示的植物高温胁迫响应机制

高温是限制植物生长和产量的主要非生物胁迫因子.近年来,蛋白质组学研究为我们从系统生物学水平深入认识植物高温胁迫应答的复杂的分子机制提供了重要信息.目前,已经分析了模式植物拟南芥、主要粮食作物(大豆、水稻和小麦)、耐热植物(匍匐剪股颖、马齿苋、假虎刺),以及野生毛葡萄、胡杨、苜蓿、半夏等应答高温胁迫过程中的蛋白质组变化特征.这些研究共鉴定到838种响应高温胁迫的蛋白质,其中534种蛋白质表达受到高温诱导,304种蛋白质表达受到抑制.本文整合分析了上述植物在应对不同程度高温胁迫(30～45 ℃处理0～10 d)时蛋白质表达模式的变化特征,为解释高温胁迫应答网络体系中重要的信号与代谢通路(如：信号转导、胁迫防御、糖类与能量代谢、光合作用、转录、蛋白质合成与命运、膜与转运等)的变化提供了证据和线索,为深入认识植物应答高温胁迫的分子调控机制奠定了坚实的基础.     

水稻资源开花期耐热性的全基因组关联分析

水稻在开花期对高温非常敏感,挖掘耐热种质并解析耐热性的遗传机制,有助于水稻的耐热性遗传改良。本研究选取205份国内外种质资源,在抽穗开花期对遇高温的稻穗进行标记,以高温下标记穗的结实率作为耐热指标,结合高密度SNP标记进行全基因组关联分析并初步预测候选基因。结果表明:不同水稻种质的耐热性差异明显,高温下的结实率最低为19.0%,平均值为64.0%,中位值为65.9%,最高值为86.6%,其中06-32、剪刀齐、娄早籼5号等17份种质的耐热性较强;全基因组关联分析共筛选到130个与耐热性显著关联的SNP标记,并鉴定到18个耐热QTL,其中6个QTL与已报道的耐热相关QTL共定位;qHT4-6与耐热性的关联度最高,根据该区间lead SNP的单倍型分类,G单倍型材料的开花期耐热性显著强于A单倍型材料,该区间附近有7个基因可能受高温调控。     

脱落酸对水稻抽穗开花期高温胁迫的诱抗效应

为探究脱落酸(ABA)对水稻(Oryza sativa)抽穗开花期高温胁迫的诱抗效应, 以江西省主推水稻品种黄华占为材料, 于孕穗期用蒸馏水、ABA溶液(10、50和100 µmol∙L^-1)、氟啶酮(FLU)和原花青素(PC) 6种溶液进行叶面喷施, 然后移入对照(CK)和高温胁迫(HS)环境处理8天, 考查籽粒活性氧(ROS)积累、抗氧化防御能力、产量构成及相关基因的表达。结果表明, 高温胁迫下, 水稻的穗长、穗重、结实率、千粒重和产量与超氧阴离子和过氧化氢含量呈显著负相关。高温胁迫下, 喷施ABA显著上调了ABA应答和抗氧化防御基因的表达, 籽粒中活性氧含量下降了8.24%-31.35%; 喷施ABA显著增加了水稻的穗长、穗重、结实率和千粒重, 显著上调了产量形成基因的表达, 增产12.73%-20.77%。高温胁迫下, 喷施FLU可抑制ABA的生物合成, 导致ROS过量积累和水稻减产; 喷施抗氧化剂PC则抑制ROS过量积累, 使产量增加。以上结果表明, 高温胁迫下, 孕穗期喷施ABA不仅能够激发ABA信号通路, 而且上调抗氧化防御能力和产量形成基因的表达, 进而提高水稻在抽穗开花期的耐热性, 达到增产目的。     

灌浆期热胁迫对小麦不同绿色器官光合性能的影响

以4个冬小麦（Triticum aestivem L.）品种（“JD8”、“Jing411”、“Centurk”和“Tam202”）为材料,研究灌浆期热胁迫对旗叶叶片、旗叶鞘、穗下节间、护颖、外疑和芒的光合性能和籽粒产量的影响。结果表明：灌浆期对泪科进行热锻炼也能增加其耐热性且各绿色器官间耐热性差异显。耐热性较强的器官为穗下节间、旗叶鞘和护颖;热敏感器官为旗叶叶片、外颖和芒。热胁迫条件下,穗下节间1旗叶鞘和护颖的细胞膜热稳定性强,光系统Ⅱ原初光能转换效率（Fv/Fm）下降速率以及叶绿素和类胡萝卜素降解速率均低于旗叶叶片、外颖和瓦,穗的净光合速率下降幅度小于旗叶。热胁迫过程中,相对耐热品种“JD8”各器官上述光合参数的下降速度均显低于其他3个热敏感品种。     

Entropic elastic processes in protein mechanisms. I. Elastic structure due to an inverse temperature transition and elasticity due to internal chain dynamics

Numerous physical characterizations clearly demonstrate that the polypentapeptide of elastin (Val1-Pro2-Gly3-Val4-Gly5)n in water undergoes an inverse temperature transition. Increase in order occurs both intermolecularly and intramolecularly on raising the temperature from 20 to 40 degrees C. The physical characterizations used to demonstrate the inverse temperature transition include microscopy, light scattering, circular dichroism, the nuclear Overhauser effect, temperature dependence of composition, nuclear magnetic resonance (NMR) relaxation, dielectric relaxation, and temperature dependence of elastomer length. At fixed extension of the cross-linked polypentapeptide elastomer, the development of elastomeric force is seen to correlate with increase in intramolecular order, that is, with the inverse temperature transition. Reversible thermal denaturation of the ordered polypentapeptide is observed with composition and circular dichroism studies, and thermal denaturation of the crosslinked elastomer is also observed with loss of elastomeric force and elastic modulus. Thus, elastomeric force is lost when the polypeptide chains are randomized due to heating at high temperature. Clearly, elastomeric force is due to nonrandom polypeptide structure. In spite of this, elastomeric force is demonstrated to be dominantly entropic in origin. The source of the entropic elastomeric force is demonstrated to be the result of internal chain dynamics, and the mechanism is called the librational entropy mechanism of elasticity. There is significant application to the finding that elastomeric force develops due to an inverse temperature transition. By changing the hydrophobicity of the polypeptide, the temperature range for the inverse temperature transition can be changed in a predictable way, and the temperature range for the development of elastomeric force follows. Thus, elastomers have been prepared where the development of elastomeric force is shifted over a 40 degrees C temperature range from a midpoint temperature of 30 degrees C for the polypentapeptide to 10 degrees C by increasing hydrophobicity with addition of a single CH2 moiety per pentamer and to 50 degrees C by decreasing hydrophobicity.(ABSTRACT TRUNCATED AT 400 WORDS)     

Environmental effects on sexual size dimorphism of a seed-feeding beetle

Sexual size dimorphism is widespread in animals but varies considerably among species and among populations within species. Much of this variation is assumed to be due to variance in selection on males versus females. However, environmental variables could affect the development of females and males differently, generating variation in dimorphism. Here we use a factorial experimental design to simultaneously examine the effects of rearing host and temperature on sexual dimorphism of the seed beetle, Callosobruchus maculatus. We found that the sexes differed in phenotypic plasticity of body size in response to rearing temperature but not rearing host, creating substantial temperature-induced variation in sexual dimorphism; females were larger than males at all temperatures, but the degree of this dimorphism was smallest at the lowest temperature. This change in dimorphism was due to a gender difference in the effect of temperature on growth rate and not due to sexual differences in plasticity of development time. Furthermore, the sex ratio (proportion males) decreased with decreasing temperature and became female-biased at the lowest temperature. This suggests that the temperature-induced change in dimorphism is potentially due to a change in non-random larval mortality of males versus females. This most important implication of this study is that rearing temperature can generate considerable intraspecific variation in the degree of sexual size dimorphism, though most studies assume that dimorphism varies little within species. Future studies should focus on whether sexual differences in phenotypic plasticity of body size are a consequence of adaptive canalization of one sex against environmental variation in temperature or whether they simply reflect a consequence of non-adaptive developmental differences between males and females.     

Modelling temperature-dependent development and survival of Otiorhynchus sulcatus (Coleoptera: Curculionidae)

Abstract 1 We conducted a laboratory experiment to quantify the stage‐specific effects of temperature on development time and survival of Otiorhynchus sulcatus (Fabricius) (Coleoptera: Curculionidae), a serious economic pest of horticultural crops. Quantification of the relationship between stage development and temperature is required to predict seasonal occurrence of particular life stages and to optimize the timing of monitoring and control tactics. 2 Temperature‐dependent survival rate was quantified using an extreme value function and showed a skewed bell shape, due to the vulnerability of the insect to high temperature in all stages. 3 The development times of O. sulcatus decreased with increasing temperature up to 27 °C for eggs and 24 °C for larvae and pupae. The nonlinear relationship between development rate and temperature was described using the Logan model, and enabled us to estimate the optimum temperature for development. 4 The inherent variation of development time was estimated from the cumulative frequency of stage emergence, which was modelled using the cumulative Weibull function. 5 The stage emergence model, which simulated the transition from one stage to the next in relation to temperature and cohort age, was constructed by incorporating stage‐specific survival and development rate submodels with the Weibull model of stage frequency. 6 Our results show a difference in optimal temperature regime among developmental stages of O. sulcatus.     

Thermoregulatory reaction in the rabbit fetuses developing under the reduced utero-placental blood flow

Rectal temperature, temperature of the brown adipose tissue, and the heart rate were studied in the rabbit foetus under intact and reduced utero-placenta blood flow in the end of the intrauterine development. With the reduced utero-placenta blood flow, bradycardia and a drop in the brown fat metabolism due, probably, to an insufficient development and functional immaturity of this tissue, were revealed.     

Temperature and enzymic control of malate metabolism in berries of Vitis vinifera

The specific activities of grape enzymes concerned with malic acid metabolism were determined at various stages of berry development under two temperature regimes. It was found that the lower acidity levels occurring in high temperature grapes at maturity are due to a changed pattern in acid breakdown rather than to reduced malic acid accumulation. The differences in acid disappearance cannot be explained by a shift in relative enzyme activities towards malate consumption with rising temperature.     

HEAT INJURY DURING FLORAL DEVELOPMENT IN COWPEA (VIGNA UNGUICULATA,FABACEAE)

High night temperatures during floral development induce male sterility in cowpea (Vigna unguiculata [L.] Walp.). The objectives of this study were to determine: the possible causes of the male sterility; the stage of floral development when damage due to heat stress occurs; and whether specific tissues are damaged during the period of sensitivity to heat. Plants were grown under controlled temperatures in both greenhouses and growth chambers in separate experiments. Floral development was normal under a night temperature of 20 C, whereas flowers developed under high night temperature (30 C) set no pods due to low pollen viability and anther indehiscence. Anthers developed under 33/30 C day/night temperatures did not exhibit endothecial formation, whereas anthers developed under 33/20 C day/night temperatures exhibited normal development of the endothecial layer. Reciprocal transfers of plants between chambers with high or optimum night temperature demonstrated that the stage of floral development most sensitive to heat stress occurs 9 to 7 d before anthesis. Anthers developed under either optimal or high night temperatures were compared cytologically. Development was similar through meiosis, but after tetrad release, which occurred 8 d before anthesis, the tapetal layer degenerated prematurely under high night temperature. Premature degeneration of the tapetal layer and lack of endothecial development may be responsible for the low pollen viability, low anther dehiscence, and low pod set under high night temperatures.     

The Effects of Temperature and Daylength on the Rate of Development of Pigeonpea

Eleven cultivars of pigeonpea, representing five different maturitygroups, were grown under controlled conditions to determinehow the rate of development from sowing to flower bud initiation(FBI) and sowing to flowering was affected by temperature anddaylength, the two environmental variables thought to have mostinfluence on reproductive development. Both temperature and daylength had substantial effects overthe range 16–32 C and 10–14 h respectively. Comparisonswithin the 12 h daylength treatment showed no consistent patternwith mean temperature. A discrete-rate analysis was used todetermine the effect on development of each of the temperaturesmaking up the various treatment combinations of day and nighttemperature. The rate of development from sowing to FBI varied among cultivars.The responses to temperature were all strongly curvilinear withoptima between 20 and 24 C. The rate of development from sowingto flowering showed a similar pattern. The effect of daylengthon the rate of development was the greatest between sowing andFBI, with the greatest sensitivity between 12 and 14 h. For the range of conditions considered, temperature had at leastas great an influence as daylength on the rates of developmentfrom sowing to FBI and from sowing to flowering. Some of theresponses to time of planting that have previously been attributedto daylength effects may, in fact, have been due to temperature.The responses to temperature of reproductive and vegetativedevelopment are very different. Phenology, Cajanus cajan     

Low temperature episodes in development of blowflies: implications for postmortem interval estimation

Traditionally the calculation of accumulated degree days or hours (ADD or ADH) involves the concept of a minimum threshold temperature below which development ceases. Hence in fluctuating conditions, where temperatures drop below this threshold, there may be periods of time when development is taken to be zero. This has important implications when the calculation of postmortem interval (PMI) is based on the ADD or ADH of larval dipterans. Normal development of larvae of the blowflies Calliphora vicina Robineau-Desvoidy and C. vomitoria L. (Diptera: Calliphoridae) at 20 degrees C was interrupted by cold episodes. The expectation was that total development time would increase by the period at low (therefore no development) temperature but the total ADD or ADH should be the same as non-cold treated cohorts. The results, however, showed that total ADH for both species decreased linearly with increasing temperature with no evidence of any minimum threshold temperature effect. The increased ADH at low temperatures may be due to either continued but reduced development or a delay in development restarting after the cold episode. Use of ADH in PMI estimations has shortcomings particularly during the winter period where low temperatures are involved or where there are sudden summer cold spells during the development period. As blowfly development progresses from egg to pupa such errors will be compounded.     

Temperature limits to early development of the New Zealand sea urchin Evechinus chloroticus (Valenciennes, 1846)

Seawater temperature is an important environmental factor for the early life stages of marine invertebrates. In this study we evaluated and described the effects of temperature during early development of E. chloroticus, identifying the optimum temperature range and upper thermal limit for successful development. The temperature range evaluated was between 15–24 °C which included the normal seawater temperatures during the spawning season in northern New Zealand, as well as the highest temperature projected by the IPCC for this region due to global warming (1–3 °C by the year 2100). Gametes from several females and males were used in the experiment. Fertilization was carried out at different temperatures and development was monitored at different time points after fertilization in each temperature. The development rate of E. chloroticus increased with an increase in seawater temperature. However, at temperatures higher than 21.5 °C the amount of abnormal development reached ∼30%. The optimum temperature for early development was between 15–21 °C, whereas the upper thermal limit was ∼24 °C. Therefore, early development of E. chloroticus is negatively affected by an increase in seawater temperature of ∼3–4 °C above current seawater temperature levels in northern New Zealand. The thermal sensitivity of early life stages of E. chloroticus could affect survival rates during early development of this species in a global warming scenario, which could impair recruitment in populations which are exposed to higher temperatures, leading to possible distributional shifts of this species.