灌浆期高温和水分逆境对冬小麦籽粒蛋白质和淀粉含量的影响

灌浆期高温和水分逆境是影响小麦籽粒产量和品质的关键气候因子。以扬麦9号、徐州26和豫麦34三个小麦品种为材料,利用人工气候室模拟灌浆期高温和水分胁迫环境,研究了花后高温及温度和水分互作对小麦籽粒蛋白质和淀粉形成的影响。结果表明,高温显著提高了小麦籽粒蛋白质含量及清蛋白、球蛋白和醇溶蛋白含量,但降低了谷蛋白含量,导致麦谷蛋白／醇溶蛋白比值降低。高温显著降低了籽粒总淀粉和支链淀粉含量及支／直比。籽粒蛋白质和淀粉及其组分形成所需的适宜昼夜温差随小麦品质类型而异,但温度水平对籽粒蛋白质和淀粉的影响较温差大。在高温和水分逆境下,温度对籽粒蛋白质和淀粉含量的影响较水分逆境大,且存在显著的互作效应。小麦籽粒蛋白质含量均表现为干旱〉对照〉渍水,以高温干旱最高,适温渍水最低;淀粉含量为对照〉干旱〉渍水,以适温对照最高,而高温渍水最低。高温和水分逆境显著提高了籽粒醇溶蛋白含量而降低了谷蛋白含量及支链淀粉含量,使蛋白质谷／醇比和淀粉支／直比降低,以高温渍水对籽粒蛋白质和淀粉组分的影响最为显著。不同品种之间,高蛋白小麦籽粒蛋白质和组分的形成受高温和水分逆境的影响更大,而低蛋白品种籽粒淀粉形成显著受温度和水分逆境的调节。分析表明,在高温和水分逆境下籽粒蛋白质含量与清蛋白和醇溶蛋白显著正相关,籽粒淀粉含量与谷蛋白、支链淀粉含量及支／直比显著正相关。     

花后高温对持绿型小麦叶片衰老及籽粒淀粉合成相关酶的影响

试验选用持绿型冬小麦(Triticum aestivum) ‘豫麦66’ (‘Ym66’)和‘潍麦8号’ (‘Wm8’)为研究材料, 以当地生产上起主导作用的冬小麦品种‘小偃22’ (‘XY22’)和‘小偃6号’ (‘XY6’)为对照。花后用塑料薄膜搭建成增温棚进行高温处理, 测定各品种绿叶数目、叶绿素和丙二醛(MDA)含量及叶片细胞膜透性, 并研究籽粒灌浆成熟期高温对持绿型小麦籽粒淀粉合成相关酶及粒重的影响。结果表明, 高温处理后, 各品种的绿叶数目和叶绿素含量都减少, MDA含量和膜透性都增加, 说明高温加速了小麦叶片衰老。同时, 各品种籽粒中与淀粉合成相关的酶(蔗糖合成酶(SS)和腺苷二磷酸葡萄糖焦磷酸化酶(AGPP)、可溶性淀粉合酶(SSS))活性都低于正常生长下的籽粒中的酶活性, 其中高温对籽粒SS和AGPP活性的影响不显著,而对籽粒SSS活性的影响显著(p = 0.015)。品种间比较, 持绿型小麦在两种处理下, 都表现出较多的绿叶数目和较高的叶绿素含量; 且3种与淀粉合成相关的酶活性也都高于非持绿型小麦, 说明持绿型小麦酶活性受高温抑制程度较小。相关性分析表明, 所有品种籽粒SS、AGPP、SSS活性都与籽粒灌浆速率成极显著的正相关(相关系数r分别为0.905、0.419和0.801)。因而, 持绿型小麦不仅具有较好的持绿特性, 而且籽粒中与淀粉合成相关的3种酶活性都较高, 这有利于其籽粒淀粉的合成, 从而增加籽粒产量。     

两种穗型冬小麦籽粒淀粉积累动态及其有关酶活性变化

花后25d内,大穗型品种豫麦66籽粒中淀粉积累比多穗型品种豫麦49慢,但花后25d后情况则相反。2个品种籽粒中淀粉积累速率的变化均呈单峰曲线,豫麦49峰值出现在花后15～20d,而豫麦66峰值则出现在花后20～25d。灌浆期豫麦66和豫麦49籽粒中蔗糖合成酶(SS)活性变化呈单峰曲线,峰值分别出现在花后20d和15d,整个灌浆期内豫麦66籽粒中SS活性高于豫麦49;2个品种籽粒中腺苷二磷酸葡萄糖焦磷酸化酶(AGPP)和淀粉分支酶(SBE)活性变化均呈单峰曲线,峰值出现在花后20d,而可溶性淀粉合成酶(SSS)活性变化则呈双峰曲线,峰值分别出现在花后10d和20d,且第二个峰值显著高于第一个。相关分析表明,SS、AGPP、SSS和SBE是影响小麦籽粒淀粉积累的关键酶。     

The relationship of starch metabolism to grain size in wheat

The present investigation was aimed at determining the levels of important enzymes of starch metabolism at different stages of grain development in wheats differing in final grain size and starch content per grain, to ascertain whether these enzymes have some relationship with grain size and/or starch content. Active starch synthesis in these varieties started from 14 days onward and continued till 35 days after anthesis. Invertase was active only during initial stages of grain development. Sucrose-UDP-glucosyltransferase had maximum activity at the 14 and/or 21 day stage and was present throughout the period of grain development. UDP- and ADP-glucose pyrophosphorylases and amylase were most active during the period of active starch synthesis and at the same time tended to parallel grain size and starch content at different stages of grain development.     

Dry weight accumulation and starch-synthesis enzymes in grain of cultured ears of three winter wheat varieties

Detached ears of three winter wheat ( Triticum aestivum L.) varieties were cultured in solution for 12 days with sucrose levels varying from 36.5 to 292 m M. The dry weight and starch content of grains increased asymptotically with the sucrose level in the solution. At 4 days of culture, glucose phosphate isomerase (EC 5.3.1.9) activity grain⁻¹ was lower with 36.5 m M than with higher sucrose levels in the medium; at 8 days, adenosinc diphosphoglucose pyrophosphorylase (EC 2.7.7.27) and (soluble plus bound) starch synthase (EC 2.4.1.21) activities grain⁻¹ were higher with 146 and 292 m M sucrose than with 36.5 and 73 m M sucrose. The multiple regression of starch content over these enzyme activities showed that starch synthase was relatively more important as an independent variable. The dry weight and starch content of grains were higher in the variety Maris Huntsman than in Splendeur and Hobbit. The water content of grains was lower in Splendeur than in the other two varieties. At 4 days the glucose phosphate isomerase, adenosine diphosphoglucose pyrophosphorylase and starch synthase activities grain⁻¹ were smaller in Splendeur than in Hobbit and Maris Huntsman and al 8 days they were higher in Maris Huntsman than in Hobbit and Splendeur. The varietal differences in starch content of grains were related to the activities of glucose phosphate isomerase and especially of starch synthase.     

控制水稻胚乳淀粉合成代谢若干关键酶基因对花后高温的响应表达

以稻米品质温度敏感型的早籼稻品种嘉早935为材料,利用人工气候箱控温试验和实时荧光定量PCR技术,探讨了不同灌浆温度(日均温分别为22和32 ℃)处理下胚乳淀粉分支酶(SBE)、淀粉去分支酶(DBE)和淀粉合酶(SS)的10个同工型基因(sbe1、sbe3、sbe4、pul、isa1、isa2、isa3、Wx、sss1和sss2a)的相对表达量差异及动态变化特征.结果表明: 淀粉合成相关功能基因对水稻灌浆期高温胁迫的响应表达方式存在明显差异,而且因同工型的类型而不同.在高温处理下,sbe1和sbe3的相对表达量显著下降,二者属于SBE类基因中对高温胁迫较敏感的主要同工型;DBE基因中,pul属于高表达的同工型,而且其对高温胁迫响应比isa1、isa2和isa3敏感;在Wx、sss1和sss2a中,sss2a的相对表达量显著低于sss1和Wx, 但sss2a和sss1对高温胁迫响应比Wx敏感,因此二者可能也是高温胁迫对胚乳淀粉结构进行调控的重要位点,尤其在水稻灌浆的中后期发挥重要作用.     

Application of a temperature‐dependent fluorescent dye (Rhodamine B) to the measurement of radiofrequency radiation‐induced temperature changes in biological samples

We have applied a non‐contact method for studying the temperature changes produced by radiofrequency (RF) radiation specifically to small biological samples. A temperature‐dependent fluorescent dye, Rhodamine B, as imaged by laser scanning confocal microscopy (LSCM) was used to do this. The results were calibrated against real‐time temperature measurements from fiber optic probes, with a calibration factor of 3.4% intensity change °C^?1 and a reproducibility of ±6%. This non‐contact method provided two‐dimensional and three‐dimensional images of temperature change and distributions in biological samples, at a spatial resolution of a few micrometers and with an estimated absolute precision of around 1.5 °C, with a differential precision of 0.4 °C. Temperature rise within tissue was found to be non‐uniform. Estimates of specific absorption rate (SAR) from absorbed power measurements were greater than those estimated from rate of temperature rise, measured at 1 min intervals, probably because this interval is too long to permit accurate estimation of initial temperature rise following start of RF exposure. Future experiments will aim to explore this. Bioelectromagnetics 30:583–590, 2009. © 2009 Wiley‐Liss, Inc.     

Relationships of endogenous plant hormones to accumulation of grain protein and starch in winter wheat under different post-anthesis soil water statusses

Accumulation of protein and starch in grain is a key process determining grain yield and quality in wheat. Under drought or waterlogging, endogenous plant hormone levels will change and may have an impact on the yield and quality of wheat. In a greenhouse experiment, four winter wheat (Triticum aestivum L.) varieties differing in grain protein content, Heimai 76, Wanmai 38, Yangmai 10 and Yangmai 9, were subjected to drought (SRWC = 4550%, DR), waterlogging (WL) and moderate water supply (SRWC = 7580%, CK), beginning from 4 days post-anthesis (DPA) to maturity. On the 10 (grain enlargement stage) and 20 (grain filling stage) DPA, endogenous abscisic acid (ABA), gibberellins (GA₁₊₃), indole-3-acetic acid (IAA) and zeatin riboside (ZR) were determined in sink and source organs of wheat plants by enzyme linked immunosorbent assay (ELISA). The patterns of hormonal changes were similar in four varieties. The ABA levels were much higher under DR and WL than under CK. Compared with CK, GA₁₊₃ levels in whole-plant under DR and WL changed a little at 10 DPA, but markedly decreased under DR and WL at 20 DPA. Changes of endogenous IAA level under DR and WL exhibited a complicated pattern, depending on organs and growth stages. Particularly at the 20 DPA, the mean levels of IAA in roots, leaves and grains decreased significantly under DR and WL. In comparison with CK, ZR levels in all organs significantly decreased under DR and WL at both stages. The correlation analyses between yields and contents of starch and protein in grains and levels and ratios of four hormones in source and sink organs indicated that the changes in yield and content of grain starch and protein under DR and WL were associated with the reduced IAA, ZR and GA₁₊₃ levels and elevated ABA level in plants, especially in grains. It was proposed that the changed levels of endogenous hormones under post-anthesis DR and WL might indirectly affect protein and starch accumulation in grains by influencing the regulatory enzymes and processes.     

晚播小麦叶片衰老代谢和粒重变化的比较研究

对７个小麦品种在晚播条件下的叶片衰老生理特性和粒重变化进行了比较研究。根据小麦叶片的衰老特征相差差异,将７个小麦品种区分为３个类型;后健型、早衰型和中间型。在小麦旗叶的衰老过程中,后健型小麦品种旗叶叶绿素和类胡萝卜素含量显著高于早衰型,脂质过氧化产物ＭＤＡ含量显著低于早衰型,小麦粒重降幅依次为早衰型〉中间型〉后健型,并讨论了活性氧代谢在小麦叶片衰老过程中可能作用。     

灌浆期高温对冬小麦籽粒氨基酸含量和组成的影响

以强筋小麦品种郑麦366和中筋小麦品种洛旱2号为材料,采用盆栽和人工气候室模拟的方法,研究了花后不同时段(灌浆前期即花后5 d,灌浆中期即花后15 d)和持续时间(处理2 d和4 d)的高温胁迫对籽粒氨基酸含量和积累量(以单粒中氨基酸含量表示)的影响。结果显示:(1)高温胁迫显著增加了小麦籽粒中必需氨基酸(EAA)、非必需氨基酸(NAA)和总氨基酸(TAA)含量,但降低了其积累量和EAA/TAA,2品种表现一致;(2)灌浆前期高温胁迫对2品种籽粒氨基酸含量的影响大于灌浆中期,而对氨基酸积累量的影响则相反;(3)高温持续时间对籽粒氨基酸含量的影响在2品种间存在差异,洛旱2号籽粒赖氨酸、EAA、NAA和TAA含量均随高温持续时间的延长显著增加,而郑麦366籽粒中上述指标仅在高温胁迫4 d下较对照增加显著;(4)从受高温胁迫的影响看,籽粒EAA/TAA对高温时段更敏感,而氨基酸含量表现为更易受高温持续时间的影响;(5)高温时段与持续时间的互作效应体现在:灌浆前期籽粒氨基酸积累量2品种均以高温胁迫4 d的影响最大,而灌浆中期则均以高温2 d的降幅最大。上述结果表明,小麦籽粒氨基酸及其组分对高温胁迫的响应不仅在品种间存在差异,且受高温时段和持续时间的影响。     

花后高温对不同耐热性小麦品种籽粒淀粉形成的影响

以耐热性不同的2个小麦品种济麦20和鲁麦21为材料,分别于花后5～9d（T1）和15～19d（T2）进行高温处理,研究了小麦花后不同阶段高温对籽粒淀粉积累、淀粉粒分布及相关酶活性的影响。结果表明,花后高温显著降低籽粒淀粉积累量;显著降低籽粒淀粉及支链淀粉含量,但提高直链淀粉含量、直／支链淀粉比例。处理间比较,他处理对籽粒淀粉积累的影响程度较T1处理大。品种间比较,高温对济麦20的影响程度较鲁麦21大。高温使A型淀粉粒的体积、数量和表面积比例显著增加,B型淀粉粒的体积、数量和表面积比例显著降低。T1处理后,两品种籽粒蔗糖含量、蔗糖合酶（SS）和腺苷二磷酸葡萄糖焦磷酸化酶（AGPP）、可溶性淀粉合酶（SSS）、束缚态淀粉合酶（GBSS）和淀粉分支酶（SBE）活性均略高于对照;但济麦20、鲁麦21上述指标分别于花后15、20d开始低于对照。他处理后,两品种籽粒蔗糖含量、SS、AGPP、SSS、GBSS和SBE活性显著低于对照,济麦20上述指标的降幅较鲁麦21大。与其它淀粉合成相关酶相比,高温对籽粒GBSS活性的影响程度较小。两品种处理间籽粒蔗糖含量、SS、AGPP、SSS、GBSS及SBE活性的变化趋势,与淀粉积累量的变化趋势基本一致。说明灌浆期高温使籽粒淀粉积累量降低,一方面是由于籽粒蔗糖供应较低引起糖源不足;另一方面则是由于灌浆中后期淀粉合成相关酶活性下降使淀粉合成受抑所致。     

不同水分条件下氮素供应对小麦植株氮代谢及籽粒蛋白质积累的影响

土壤水分逆境是限制小麦籽粒品质形成的重要生态因子,明确土壤水分逆境下小麦籽粒品质形成的生理机制及调优技术途径,对于深化小麦品质生理生态研究和指导小麦调优栽培具有重要的理论意义和应用前景。在防雨池栽条件下,设置渍水、干旱和对照3个水分处理,每个水分处理下再设置120和240 kg.hm-2两个施氮水平,研究了花后渍水和干旱逆境下氮素对两个籽粒蛋白质含量不同的小麦品种植株氮代谢和籽粒蛋白质积累的影响。结果表明,与正常水分处理相比,花后干旱和渍水均降低旗叶硝酸还原酶活性、叶片总氮含量和游离氨基酸含量。干旱处理提高了茎鞘总氮与游离氨基酸含量以及籽粒蛋白质含量,而渍水处理则使其降低。水分逆境下增施氮肥提高旗叶硝酸还原酶活性、叶片与茎鞘总氮和游离氨基酸含量以及籽粒游离氨基酸和蛋白质含量。花后干旱和渍水均显著降低了小麦籽粒产量和蛋白质产量。增施氮肥提高适宜水分和水分亏缺条件下小麦籽粒产量,但不利于渍水下小麦产量的提高。这说明,花后渍水和干旱逆境下施用氮肥对小麦植株氮代谢和籽粒蛋白质积累有明显的调节效应。     

Carbon balance and source‐sink metabolic changes in winter wheat exposed to high night‐time temperature

Carbon loss under high night‐time temperature (HNT) leads to significant reduction in wheat yield. Growth chamber studies were carried out using six winter wheat genotypes, to unravel postheading HNT (23°C)–induced alterations in carbon balance, source‐sink metabolic changes, yield, and yield‐related traits compared with control (15°C) conditions. Four of the six tested genotypes recorded a significant increase in night respiration after 4 days of HNT exposure, with all the cultivars regulating carbon loss and demonstrating different degree of acclimation to extended HNT exposure. Metabolite profiling indicated carbohydrate metabolism in spikes and activation of the TriCarboxylic Acid (TCA) cycle in leaves as important pathways operating under HNT exposure. A significant increase in sugars, sugar‐alcohols, and phosphate in spikes of the tolerant genotype (Tascosa) indicated osmolytes and membrane protective mechanisms acting against HNT damage. Enhanced night respiration under HNT resulted in higher accumulation of TCA cycle intermediates like isocitrate and fumarate in leaves of the susceptible genotype (TX86A5606). Lower grain number due to lesser productive spikes and reduced grain weight due to shorter grain‐filling duration determined HNT‐induced yield loss in winter wheat. Traits and mechanisms identified will help catalyze the development of physiological and metabolic markers for breeding HNT‐tolerant wheat.     

光温因子对大田冬小麦累积生物量的影响

为了探索光、温因子对冬小麦各生育阶段生物量的影响及冬小麦各组织器官生物量的变化规律,利用甘肃省西峰农业气象试验站1981-2008年冬小麦生产年度物候期、产量分析要素等观测资料、1995-2008年冬小麦生产年度三叶期、越冬期、拔节期、抽穗期、乳熟期及成熟期生物量测定资料及相应时段的温度、日照资料,分析了冬小麦生物量变化过程及光温因子综合作用辐热积对各生育阶段生物量的影响.结果表明：冬小麦全生育期生物量的累积过程呈“S”型曲线,抽穗期、乳熟期生物量达到最大.自1981年以来,抽穗期、乳熟期的辐热积以3.314 MJ·m^-2·a^-1的速度上升,其他各生育阶段辐热积随年份呈抛物线变化;返青期、拔节期及乳熟期、成熟期辐热积在20世纪90年代较大,20世纪80年代及21世纪初较小;拔节期、抽穗期辐热积在20世纪90年代较小,20世纪80年代及21世纪初较大.各生育阶段辐热积与产量相关显著.各生育阶段的叶面积指数与该阶段的辐热积利用率呈显著相关,拔节期及抽穗期叶面积指数增加1,其辐热积利用率分别增加0.049和0.259 g·MJ^-1.     

高温、干旱及其互作对两个筋力小麦品种淀粉糊化特性的影响

以强筋和弱筋的两个代表性小麦品种为材料,采用盆栽与人工气候箱模拟的方法,研究了花后不同时期高温、干旱及其互作对籽粒淀粉糊化特性的影响。结果表明,高温和干旱均显著影响淀粉糊化特性,但两品种表现有所不同:高温胁迫使强筋小麦品种豫麦34的峰值黏度、最终黏度(除花后5 d外)、稀懈值(除花后15 d外)和反弹值显著增大;而弱筋小麦品种豫麦50低谷黏度和最终黏度显著下降,其峰值黏度、反弹值变化不明显,从不同时期看,花后15 d影响较大。干旱胁迫使豫麦34多数黏度参数增大;而使豫麦50峰值黏度、反弹值和稀懈值下降,其低谷黏度和最终黏度在灌浆前期和中期干旱胁迫下增大,后期干旱胁迫则明显下降。研究结果还表明,花后高温与干旱胁迫对小麦黏度参数的影响存在显著的互作效应。从F值大小看,互作对弱筋小麦品种豫麦50多数黏度参数影响较大,而对强筋小麦品种豫麦34淀粉黏度参数影响较小,反映了高温、干旱及其互作对小麦淀粉特性的影响存在着显著的基因型差异。     

灌溉对干旱区冬小麦干物质积累、分配和产量的影响

为探明灌溉对干旱区冬小麦(Triticum aestivum)产量、水分利用效率(WUE)、干物质积累及分配等的影响, 以甘肃河西走廊冬小麦适宜种植品种‘临抗2号’为材料进行了研究。在冬季灌水180 mm的条件下, 生育期以灌水量和灌水次数等共设置5个处理, 分别为: 拔节期灌水量165 mm (W1)、拔节期灌水量120 mm +抽穗期灌水量105 mm (W2)、拔节期灌水量105 mm +抽穗期灌水量105 mm +灌浆期灌水量105 mm (W3)、拔节期灌水量75 mm +抽穗期灌水量75 mm +灌浆期灌水量75 mm (W4)、拔节期灌水量105 mm +抽穗期灌水量75 mm +灌浆期灌水量45 mm (W5)。结果表明: 随着生育期的推进, 土壤有效含水量(AWC)受灌水次数及灌水量影响更加明显; W3、W4处理的土壤各层AWC在灌浆期均较高; 叶面积指数(LAI)下降慢, 延缓了生育后期的衰老; 生育后期干物质积累增加, 提高了穗粒数、千粒重和籽粒产量。籽粒产量以W3处理最高, 但W4具有最高的WUE, 且籽粒产量与W3无显著差异, 但W4较灌溉总量相同的W2和W5以及灌水量最少的W1具有明显的指标优势。W1、W2、W5处理灌浆期各层土壤AWC均较低, 花后LAI下降快, 干物质积累减少, 灌浆持续期缩短, 穗粒数和千粒重减少, 最终表现为籽粒产量和WUE下降。灌浆期水分胁迫可促进花前储存碳库向籽粒的再转运, 并随着干旱胁迫的加重而提高, 对籽粒产量起补偿作用; 水分胁迫提高了灌浆速率, 但缩短了灌浆持续期。相关性分析表明, 灌浆持续期、有效灌浆持续期、有效灌浆期粒重增加值和最大籽粒灌浆速率出现时间与千粒重和籽粒产量均呈正相关。综合考虑, 拔节、抽穗及灌浆期各灌溉75 mm是高产高WUE的最佳灌水方案。     

水氮互作对小麦籽粒蛋白质、淀粉含量及其组分的影响

以两个不同品质类型的小麦品种（强筋品种豫麦34、弱筋品种豫麦50）为材料,在大田条件下,研究了3个灌水处理（W₁：拔节水;W₂：拔节水+花后15 d灌浆水;W₃：拔节水+灌浆水+花后28 d麦黄水）和3个氮肥水平（0、150、270 kg·hm^-2）对籽粒蛋白质、淀粉含量及其组分的影响.结果表明：270 kg·hm^-2的施氮量有利于提高强筋小麦（豫麦34）籽粒蛋白质含量,籽粒清蛋白、醇溶蛋白和谷蛋白含量明显提高,谷/醇增大;支链淀粉和总淀粉含量提高,直/支下降;籽粒产量增加.弱筋小麦（豫麦50）在150 kg·hm^-2 的施氮量下,清蛋白和醇溶蛋白含量增加,球蛋白和谷蛋白含量下降,谷/醇降低;支链淀粉和总淀粉含量提高;不施氮肥或氮肥施用过多（270 kg·hm^-2）均影响籽粒蛋白质和淀粉的积累,使产量下降.W₂处理促进了籽粒蛋白质和淀粉积累,W₁或W₃处理均不利于籽粒蛋白质和淀粉积累,且导致籽粒产量下降.水、氮互作效应中,强筋和弱筋小麦分别以全生育期270 kg·hm^-2和150 kg·hm^-2施氮量配合拔节水+灌浆水（W₂）为比较理想的水氮运筹方式.     

Acute dim light at night increases body mass,alters metabolism,and shifts core body temperature circadian rhythms

The circadian system is primarily entrained by the ambient light environment and is fundamentally linked to metabolism. Mounting evidence suggests a causal relationship among aberrant light exposure, shift work, and metabolic disease. Previous research has demonstrated deleterious metabolic phenotypes elicited by chronic (>4 weeks) exposure to dim light at night (DLAN) (～5?lux). However, the metabolic effects of short-term (<2 weeks) exposure to DLAN are unspecified. We hypothesized that metabolic alterations would arise in response to just 2 weeks of DLAN. Specifically, we predicted that mice exposed to dim light would gain more body mass, alter whole body metabolism, and display altered body temperature (T_b) and activity rhythms compared to mice maintained in dark nights. Our data largely support these predictions; DLAN mice gained significantly more mass, reduced whole body energy expenditure, increased carbohydrate over fat oxidation, and altered temperature circadian rhythms. Importantly, these alterations occurred despite similar activity locomotor levels (and rhythms) and total food intake between groups. Peripheral clocks are potently entrained by body temperature rhythms, and the deregulation of body temperature we observed may contribute to metabolic problems due to “internal desynchrony” between the central circadian oscillator and temperature sensitive peripheral clocks. We conclude that even relatively short-term exposure to low levels of nighttime light can influence metabolism to increase mass gain.     

不同酸度酸雨对小麦花后氮硫代谢和籽粒蛋白组分的影响

酸雨是中国重要的环境问题,为研究酸雨对小麦籽粒品质的可能影响,以小麦品种扬麦15和汶农17为材料开展盆栽试验,研究了不同酸度(pH2.5、p H4.0和p H5.6)酸雨对小麦花后氮硫代谢关键酶活性和籽粒蛋白质含量及组分的影响。结果显示:酸雨处理抑制叶片硝酸还原酶(NR)活性,提高了扬麦15整个灌浆期及汶农17灌浆中后期叶片谷氨酰胺合成酶(GS)活性,促进了叶片蛋白的降解,降低了叶片可溶性蛋白含量。不同酸度酸雨提高了成熟期籽粒中蛋白质含量,酸度越强,增加幅度越大,籽粒中各蛋白组分含量和大部分氨基酸含量也有明显提高。酸雨提高了扬麦15叶片丝氨酸乙酰转移酶(SAT)和O-乙酰丝氨酸硫裂解酶(OAS-TL)活性,但对汶农17硫代谢关键酶活性影响较小,酸雨处理还提高了籽粒中二硫键和含硫氨基酸含量。可见酸雨对小麦氮硫代谢有不同程度影响,进而影响了小麦籽粒蛋白质含量和组成,酸度越强影响越大,但不同品种对酸雨响应有一定差异。