Altered Expression of Transcription Factor Genes in Rice Flag Leaf under Low Nitrogen Stress

The response of transcription factor genes to low nitrogen stress was studied to provide molecular basis for improving the absorption and utilization efficiency of nitrogen fertilizer in rice. The agilent rice genome arrays were used to study the varied expression of transcription factor genes in two rice varieties （SN 196 and Toyonishhiki） with different chlorophyll contents under low nitrogen stress. The results showed that a total of 53 transcription factor genes （35 down-regulated and 18 up-regulated genes at the transcription level） in flag leaves of super-green rice SN196 and 27 transcription factor genes （21 down-regulated and 6 up-regulated genes at the transcription level） in flag leaves of Toyonishiki were affected by low nitrogen stress. Among those nitrogen-responsive genes, 48 transcription factor genes in SN196 and 22 in Toyonishiki were variety-specific. There were overlapped transcription factor genes responded to low nitrogen stress between SN196 and Toyonishiki, with 1 up-regulated and 4 down-regulated at the transcription level. Distributions of low nitrogen responsive genes on chromosomes were different in two rice varieties.

Research on Physiological Characteristics of Tall Fescue under Nitrogen Stress

[Objective] This study aimed to investigate the physiological characteristics of tall fescue under nitrogen stress. [Method] A series of physiological changes in protein content, chlorophyll content, enzyme activities and amino acids contents in tall fescue under nitrogen stress were analyzed. [Result] Under nitrogen stress, the leaf chlorophyll content in tall fescue was reduced, and superoxide dismutase（SOD）,peroxidase（POD）, glutamine synthetase（GS） activities were increased. Among the 18 kinds of amino acids analyzed, the contents of asparagine, serine, glycine, glutamine, glutamic acid, aspartic acid, threonine, alanine, arginine, methionine, valine,isoleucine and leucine were significantly reduced in tall fescue under nitrogen stress.[Conclusion] This study will provide certain reference for rational application of nitrogen and exploration of plant ecological potential in the future.

Effects of dietary arginine levels on growth performance,body composition, serum biochemical indices and resistance ability against ammonia-nitrogen stress in juvenile yellow catfish(Pelteobagrus fulvidraco)

This experiment was conducted to investigate the effects of dietary arginine levels on growth performance, body composition, serum biochemical indices and resistance ability against ammonia-nitrogen stress in juvenile yellow catfish(Pelteobagrus fulvidraco). Five isonitrogenous and isolipidic diets(42%protein and 9% lipid) were formulated to contain graded levels of arginine(2.44%, 2.64%, 2.81%, 3.01% and3.23% of diet), by supplementing L-Arginine HCI. Seven hundred juvenile yellow catfish with an initial average body weight of 1.13 ± 0.02 g were randomly divided into 5 groups with 4 replicates of 35 fish each and each group was fed one of the diets. After 56 d feeding, fish were exposed to 100 mg/L of ammonia-nitrogen for 72 h. The results showed that weight gain(WG) and specific growth rate(SGR) in2.64% and 2.81% groups were significantly higher than those in 3.23% group(P < 0.05). The feed conversation ratio(FCR) in 2,64%, 2,81% and 3.01% groups was significantly decreased when compared with3,23% group. The protein efficiency ratio(PER) in 2.64% group was significantly higher than that in 2.44%and 3.23% groups(P < 0.05). The condition factor(CF) of fish was significantly higher in 2.81% group than that in 2,44% group(P < 0.05). Dietary arginine levels had no significant effect on hepatosomatic index(HSI), viscerosomatic index(VSI), and whole-body dry matter, crude protein, crude lipid, ash contents, as well as serum total protein(TP), triglyceride(TG), glucose(GLU), urea nitrogen(UN) contents and aspartate aminotransferase(AST), alanine aminotransferase(ALT) activities(P> 0.05). After the fish were challenged to ammonia-nitrogen for 72 h, their cumulative mortality rate in 2.81% group was significantly lower than that in 2.44% group(P < 0.05). The results suggested that dietary arginine level at 2.81%could optimize anti-ammonia-nitrogen stress ability of juvenile yellow catfish and a level of 3.23%arginine seemed to depress the growth performance of fish and decreased their tolerance to the ammonia-nitrogen stress under current study. A quadratic regression analysis based on WG indicated that the optimal dietary arginine requirement of juvenile yellow catfish was estimated to be 2.74% of the diet(6.45% of dietary protein) under current culture conditions.

The Relative Importance of Nitrogen vs. Moisture Stress May Drive Intraspecific Variations in the SLA-RGR Relationship: The Case of <i>Picea mariana</i>Seedlings

Plants acclimate to nitrogen (N) or moisture stress by respectively increasing photosynthetic N use efficiency (PNUE) or water use efficiency (WUE), in order to maximize their relative growth rate (RGR). These two phenotypic adaptations have opposite effects on specific leaf area (SLA). Thus, intraspecific variations in the SLA-RGR relationship should reflect the relative importance of N vs. moisture stress in plants. In this study, we measured needle gas exchanges and N concentrations in order to derive PNUE and WUE, as well as SLA and RGR of black spruce (Picea mariana) seedlings growing on a rapidly drained site in the presence or absence of Kalmia angustifolia. The eradication of Kalmia had resulted in a ~140% increase in seedling growth over a 6 year period. We found a negative SLA-RGR relationship where Kalmia had been eradicated, and a positive one where Kalmia had been maintained. Kalmia eradication resulted in higher WUE when measurements were made directly on the seedlings, and in lower PNUE when twigs were rehydrated prior to gas exchange measurements. Our data suggest that the bigger seedlings on Kalmia-eradicated plots increase RGR by decreasing SLA, as a means of coping with moisture stress. By contrast, increasing SLA on noneradicated plots may be a means of coping with nutrient stress exerted by Kalmia. The SLA-RGR relationship could potentially be used to identify the limiting resource for black spruce seedlings in different environments.

Weakened carbon and nitrogen metabolisms under post-silking heat stress reduce the yield and dry matter accumulation in waxy maize

Post-silking high temperature is one of the abiotic factors that affects waxy maize(Zea mays L. sinensis Kulesh) growth in southern China. We conducted a pot trial in 2016–2017 to study the effects of post-silking daytime heat stress(35°C) on the activities of enzymes involved in leaf carbon and nitrogen metabolisms and leaf reactive oxygen species(ROS) and water contents. This study could improve our understanding on dry matter accumulation and translocation and grain yield production. Results indicated that decreased grain number and weight under heat stress led to yield loss, which decreased by 20.8 and 20.0% in 2016 and 2017, respectively. High temperature reduced post-silking dry matter accumulation(16.1 and 29.5% in 2016 and 2017, respectively) and promoted translocation of pre-silking photoassimilates stored in vegetative organs, especially in leaf. The lower leaf water content and chlorophyll SPAD value, and higher ROS(H2O2 and O2^-·) content under heat stress conditions indicated accelerated senescent rate. The weak activities of phosphoenolpyruvate carboxylase(PEPCase), Ribulose-1,5-bisphosphate carboxylase(Ru BPCase), nitrate reductase(NR), and glutamine synthase(GS) indicated that leaf carbon and nitrogen metabolisms were suppressed when the plants suffered from a high temperature during grain filling. Correlation analysis results indicated that the reduced grain yield was mainly caused by the decreased leaf water content, weakened NR activity, and increased H2O2 content. The increased accumulation of grain weight and post-silking dry matter and the reduced translocation amount in leaf was mainly due to the increased chlorophyll SPAD value and NR activity. Reduced PEPCase and Ru BPCase activities did not affect dry matter accumulation and translocation and grain yield. In conclusion, post-silking heat stress down-regulated the leaf NR and GS activities, increased the leafwater loss rate, increased ROS generation, and induced pre-silking carbohydrate translocation. However, it reduced the post-silking direct photoassimilate deposition, ultimately, leading to grain yield loss.

Stress Corrosion Cracking of Nitrogen-containing Stainless Steel 316LN in High Temperature Water Environments

Stress corrosion cracking （SCC） of stainless steels and Ni-based alloys in high temperature water coolant is one of the key problems affecting the safe operation of nuclear power plants （NPPs）. The nitrogen-added stainless steel is a kind of possible candidate materials for mitigating SCC since reducing the carbon content and adding nitrogen to offset the loss in strength caused by the decrease in carbon content can mitigate the problem of sensitization. However, the reports of SCC of nitrogen-added stainless steels in high temperature water are few available. The effects of applied potential and sensitization treatment on the SCC of a newly developed nitrogen-containing stainless steel （SS） 316LN in high temperature water doped with chloride at 250 ℃ were studied by using slow strain rate tests （SSRTs）. The SSRT results are compared with our data previously published for 316 SS without nitrogen and 304NG SS with nitrogen, and the possible mechanism affecting the SCC behaviors of the studied steels is also discussed based on SSRT and microstucture analysis results. The susceptibility to cracking of 316LN SS normally increases with increasing potential. The susceptibility to SCC of 316LN SS was less than that of 316 SS and 304NG SS. Sensitization treatment at 700℃ for 30 h showed little effect on the S CC of 316LN S S and significant effect on the S CC of 316 S S. The predominant cracking mode for the 316LN S S in both annealed state and the state after the sensitization treatment was transgranular. The presented conditions of mitigating stress corrosion cracking are some useful information for the safe use of 316LN SS in NPPs.

Physiological Mechanism of Nitrogen Mediating Cotton (<i>Gossypium hirsutum</i>L.) Seedlings Growth under Water-Stress Conditions

The objective of this investigation was to study the effects of nitrogen on tolerance to water-stress in cotton (Gossypium hirsutum L.) seedlings. Growth chamber studies with pots of washed sand were carried out in Fayetteville, USA, and Nanjing, Chinawith three water conditions (well-watered, drought-stressed, and waterlogging), and three nitrogen rates, low nitrogen (16 mM, approximately 224 mg N·l–1 water), medium nitrogen (24 mM, approximately 448 mg N·l–1 water) and high nitrogen (32 mM, approximately 672 mg N·l–1 water), respectively. The results showed that water-stress treatments reduced plant biomass, C/N ratio, root vigor and leaf photosynthesis (Pn). The plant response to water-stress resistance was affected by nitrogen, and was correlated with the activities of antioxidant enzymes. The changes of anti-oxidant enzymes was the highest in the low nitrogen rate in the drought-stressed and waterlogged cotton seedlings. Malondialdehyde (MDA) content increased significantly in the water-stress treatments, and was the lowest in the low nitrogen rate. There was a significant reduction of N accumulation under water stress. Low-nitrogen treatmentincreased C accumulation, while high-nitrogen treatment decreased N accumulation. Root vigor was decreased by water stress, and was highest in the low-nitrogen rate. After terminating the water stress, N application promoted root vigor, especially in waterlogged seedlings. The trends of Pn weresimilarto that of root vigor. These results suggested that low N application may contribute to cotton drought tolerance by enhancing the activity of antioxidant enzymes and conse-quently decreasing lipid peroxidation, and enhancing root vigor. However, higher N should be applied to waterlog- ging-stressed cotton seedlings after terminating waterlogging.

Effects of nitrogen nutritional stress on the morphological and yield parameters of tomato(Solanum lycopersicum L.)

This investigation was carried out to better understand the effects of nitrogen stress on the growth and yield of tomato （Solanum lycopersicon L.）. Seeds of S. lycopersicon （Ife No. 1 variety） were collected from the Osun-State Ministry of Agriculture, Oshogbo, Nigeria and planted in analyzed top soil. The plants were grown for a period of five weeks within which they were supplied with water and kept under optimum environmental conditions that enhanced normal growth. After this period, the plants were subjected to different levels of nitrogen stress which include： plants supplied with dis- tilled water only （n）, plants supplied with complete nutrient solution （N）, plants supplied with nutrient solution in which nitrogen concentration sources was increased by a factor of 5 （N5）, and plants supplied with nutrient solution in which nitrogen concentration sources was increased by a factor of 10 （N10）. Analysis of Variance （ANOVA） results shows that there is no significant effect of stress on the growth and morphological parameters of tomato plants. However, there was a significant effect of nitrogen stress on the yield parameters. Nitrogen stress also caused an increase in the number and size of fruits produced in plants subjected with high nitrogen concentration.

Increase of nitrogen to promote growth of poplar seedlings and enhance photosynthesis under NaCl stress

The solution culture method was used to study the effect of increasing nitrogen on the growth and pho-tosynthesis of poplar seedlings under 100 mmol L-1 NaCl stress. I Increase in nitrogen reduced stomatal limitation of leaves under NaCl stress, improved utilization of CO2 by mesophyll cells, enhanced photosynthetic carbon assimi-lation capacity, significantly alleviated saline damage of NaCl, and promoted the accumulation of aboveground and root biomass. I Increased nitrogen enhanced photochemical efficiency (ΦPSⅡ) and electron transport rates, relieved the reduction of maximum photochemical efficiency (Fv/Fm) under NaCl, and reduced the degree of photoinhibition caused by NaCl stress. Increased nitrogen applications reduced the proportion of energy dissipating in the form of ineffective heat energy and hence a greater proportion of light energy absorbed by leaves was allocated to photo-chemical reactions. Under treatment with increased nitro-gen, the synergistic effect of heat dissipation and the xanthophyll cycle in the leaves effectively protected pho-tosynthetic PSⅡ and enhanced light energy utilization of leaves under NaCl stress. The increased nitrogen promoted photosynthetic electron supply and transport ability under NaCl stress evident in enhanced functioning of the oxygen-evolving complex on the electron donor side of PS Ⅱ. It increased the ability of the receptor pool to accept electrons on the PSII electron acceptor side and improved the sta-bility of thylakoid membranes under NaCl stress. Therefore, increasing nitrogen applications under NaCl stress can promote poplar growth by improving the effi-ciency of light energy utilization.

Effects of Application of Nitrogen, Potassium and Glycinebetaine on Alleviation of Water Stress to Summer Maize

A pot experiment was conducted under water deficit and adequate water-supplied conditions with two maize genetypic varieties （Shaandan 9 and Shaandan 911） to study the effects of nitrogen, potassium and glycinebetaine （GlyBet） on the dry matter and grain yields as well as water use efficiency （WUE）. Determinations were made at different stages of the two varieties for revealing the function of these factors in increasing plant resistance to drought. Results showed that under a water-stressed condition, dry matter and grain yield were significantly reduced. However, the response of the two varieties to water stress was different： Shaandan 9 was significantly higher in dry matter and grain yields, and therefore could be regarded as a drought-resistant variety compared to Shaandan 911.Application of nitrogen, potassium and glycinebetaine raised dry matter and grain yield to different levels, and thereby alleviated the water stress and increased water use efficiency. These effects were higher for Shaandan 911 than for Shaandan 9. Under water-stressed conditions application of N fertilizer, either at low rate or at high rate, significantly increased dry matter, grain yield and water use efficiency. A significant different effect was found for Shaandan 911 between N rates, but not so for Shaandan 9. However, with supplemental water supply, effects of N fertilization were obviously decreased, showing that in addition to supplying nutrient, N fertilizer has a function in increasing drought-resistance of the crop. Potassium and glycinebetaine exhibited a remarkable function in increasing dry matter and grain yields as well as water use efficiency under water stress while such effects were obviously declined, even vanished, with supplemental water supply, indicating the important contribution of these factors in rise of drought-resistance ability of a crop.

In vitro Anthocyanin Induction and Metabolite Analysis in Malus spectabilis Leaves Under Low Nitrogen Conditions

Anthocyanins are the most widely produced secondary metabolites in plants,and they play an important role in plant growth and reproduction.The nitrogen source is an important factor affecting anthocyanin production,but the nitrogen concentrations on metabolism and the underlying genetic basis remain unclear.In this study,in vitro anthocyanin induction was conducted on Malus spectabilis.The leaf explants were cultivated in media containing different nitrogen concentrations.The results suggested that when the nitrogen contents decreased in limit,the color of leaf explants turned from green to red,and increased anthocyanin accumulation led to a change in phenotype.Furthermore,the content of other flavonoids,such as dihydroquercetin,epicatechin,and catechin,increased under low nitrogen conditions.The transcription levels of the general flavonoid pathway genes,from phenylalanine ammonia lyase(PAL)to anthocyanidin synthase(ANS),were associated with the concentration of corresponding flavonoid compounds and phenotype changes.In particular,the expression level of ANS increased substantially under a low nitrogen treatment,which was significantly and positively correlated with the anthocyanin levels(R2=0.72,P<0.05).The increased expression patterns of anthocyanin pathway genes were similar to that of the transcription factor MYB10.We further verified MYB10 played an important role in the anthocyanin pathway in leaves of Malus spectabilis.These results suggested that we can improve the desirable ornamental plant phenotypes by controlling nitrogen content.This process may offer clues to further development of new agricultural practices.

碱性环境下急性氨氮胁迫对虹鳟抗氧化能力和非特异性免疫的影响

为探究碱性环境下急性氨氮胁迫对虹鳟(Oncorhynchus mykiss)抗氧化和免疫功能的影响,研究设置3个不同氨氮处理组(0.86、1.73和2.59 mg/L)对虹鳟进行96h急性胁迫实验,测定肝脏和血清中抗氧化与免疫酶的活性及肝脏中相关基因的表达水平。结果显示,在不同浓度氨氮胁迫下,虹鳟肝脏CAT、T-AOC、T-SOD活性和MDA含量均呈现先上升后下降的变化趋势,血清T-AOC活性呈先下降后上升的变化,其他酶活性变化则与肝脏一致;高浓度组肝脏MDA含量在胁迫48h时最低,而T-SOD活性最高。肝脏和血清免疫相关酶GPT、GOT、ACP和AKP的活性在不同浓度的氨氮胁迫下呈先升高后降低的变化趋势;在96h时,不同浓度组肝脏和血清中GPT活性均显著高于对照组(P<0.05)。不同浓度组肝脏抗氧化相关基因(cu/zn-sod、mn-sod和cat)表达量在6h时均高于对照组;在12h时,hsp90基因的表达量高于对照组,而hsp70基因的表达量低于对照组。以上结果表明,在胁迫初期虹鳟抗氧化和免疫酶活性被诱导激活,抗氧化与免疫相关基因表达量上调;随着胁迫时间的延长,机体抗氧化与免疫功能受到抑制,相关酶活性与基因表达量下调。研究为深入探究虹鳟氨氮胁迫下抗氧化和免疫系统的应激机制提供了基础资料。

高温煤岩液氮冷却后巴西劈裂破坏及声发射演化特征

采用压裂技术提升煤层气储层渗透性是强化煤层气开发的重要途径。对于深部高温煤层气储层,液氮压裂技术通过在煤层中注入低温液氮形成显著热应力,基于冷冲击作用可实现对煤层气储层的致裂增渗。为研究液氮作用对高温煤岩的力学特性及损伤破裂特征的影响机制,对加热至不同温度条件下的煤样进行液氮冷却处理,通过波速测试和巴西劈裂测试,研究液氮对高温煤样波速、强度、声发射和裂纹演化等特征及破裂模式的影响机制。结果表明:高温煤样在液氮冷却作用后,力学性能出现了显著劣化,P波波速降低,超声频率分化严重,主频由51.10 kHz降至40.88 kHz。煤样逐渐由脆性破坏向延性破坏转变,巴西劈裂模量和脆性指数降幅最高分别为67%和75%。在巴西劈裂荷载下,煤样内部声发射信号均表现为低RA值、高AF值;煤样内部破坏形式主要为拉伸破坏,其次为剪切破坏。随着煤样初始温度的增加,煤样断裂面上形成多个起伏区域,3维形貌扫描的最大波峰与最大波谷高度差最高可达37.60 mm。液氮冷却诱导的微裂隙交叉扩展形成复杂的裂纹网络,进而导致局部失效区域的形成和煤样断裂面复杂化。表观裂纹分形维数在初始加热温度为100℃时达到最大值,由初始20℃时的0.50增加到1.83。研究结果可为深部高温煤层液氮压裂设计提供理论参考。

氮素对开花期受旱玉米根系特性及产量形成的影响

以抗旱型玉米品种‘郑单958’和干旱敏感型品种‘先玉335’为试验材料,采用土柱栽培的方式探究不同水分处理(正常灌水W1,干旱胁迫W0)和不同氮素水平(N0:0 g·株^(-1),N1:7.2 g·株^(-1))对开花期受旱玉米根系形态结构和生理特性及地上部生长与籽粒产量的影响。结果表明:开花期干旱胁迫抑制气生根和浅层节根的发生与生长,导致根系的总根长、总根表面积和总根体积较正常灌溉处理分别下降1.30%~38.73%、4.95%~42.42%和17.69%~51.58%;氮素的施用促进气生根及浅层节根的生长,缓解了干旱胁迫对根系生长的不利影响。开花期干旱导致根系活跃吸收面积比例降低5.56%~18.46%,施用氮肥后干旱处理下玉米根系活跃吸收面积比例和根系活力分别提升7.54%~11.65%和40.79%~44.84%。玉米地上部生长对干旱和氮素的响应规律与根系表现基本一致,干旱胁迫导致叶片SPAD、叶面积、植株生物量显著降低,而施用氮肥后叶片SPAD、叶面积、植株生物量分别提升28.57%~31.25%、14.60%~35.76%、14.72%~42.63%;施氮处理的耐旱指数较不施氮处理提升1.59倍~3.52倍。开花期干旱导致收获期玉米穗粒数降低12.97%~30.69%,氮素亏缺主要影响百粒重(降幅7.48%~38.94%),施用氮肥促进开花期受旱玉米籽粒产量提升19.82%~166.47%。‘先玉335’对干旱胁迫及氮素调节的响应较‘郑单9585’更为敏感。综上,适量施用氮肥促进了开花期受旱玉米根系的生长及生理活性提高,有利于植株对土壤水分和养分的吸收,同时促进地上部的物质生产和籽粒产量建成,从而有效提升玉米抗旱性能。

细菌的耐盐调控及其在高盐生物脱氮除磷工艺中的应用

生物脱氮除磷(BNR)工艺在氮磷等营养物生物去除过程难免受到盐度变化的冲击,掌握细菌的应对机制,策略性调控系统运行方式,对经济、高效地维持系统的稳定至关重要。本文汇总简述了以下最新研究成果:(1)耐盐微生物能根据环境中盐度的变化,快速地与环境交换水、小分子氨基酸、甘油、多糖类有机物以及钾、钠离子等无机物来平衡细胞渗透压;(2)极端嗜盐菌具有特殊的细胞结构,能够充分利用各类能源(光、电以及化学势比脂肪酸更低的电子供体),促进高能量贮存物(聚糖、聚磷、聚羟基烷酸酯、聚硫)的积累;(3)利用交替厌氧/缺氧/好氧生物膜工艺,接种高盐污泥并同步利用海水驯化生物膜菌群,且借助各种高能物质存储与消耗的偶联反应,可驱动高盐环境中同步硝化/反硝化(除磷)过程的高效运行。最后指出,如何高效地在维持系统稳定性同时设计出合理的工艺与反应器形式,如何通过外源性能源(光、电、化能物质)的输入来调控微生物高盐环境的适应性,是生物脱氮除磷系统的理论研究以及工程实践中亟待解决的问题。

Metabolic and physiological regulation of Chlorella sp.(Trebouxiophyceae, Chlorophyta) under nitrogen deprivation

A freshwater green microalgae Chlorella sp., UMACC344 was shown to produce high lipid content and has the potential to be used as feedstock for biofuel production. In this study, photosynthetic effciency, biochemical pro?les and non-targeted metabolic pro?ling were studied to compare between the nitrogen-replete and deplete conditions. Slowed growth, change in photosynthetic pigments and lowered photosynthetic effciency were observed in response to nitrogen deprivation. Biochemical pro?les of the cultures showed an increased level of carbohydrate, lipids and total fatty acids, while the total soluble protein content was lowered. A trend of fatty acid saturation was observed in the nitrogen-deplete culture with an increase in the level of saturated fatty acids especially C16:0 and C18:0, accompanied by a decrease in proportions of monounsaturated and polyunsaturated fatty acids. Fifty-nine metabolites, including amino acids, lipids, phytochemical compounds, vitamins and cofactors were signi?cantly dysregulated and annotated in this study. Pathway mapping analysis revealed a rewiring of metabolic pathways in the cells, particularly purine, carotenoid, nicotinate and nicotinamide, and amino acid metabolisms. Within the treatment period of nitrogen deprivation, the key processes involved were reshu ? ing of nitrogen from proteins and photosynthetic machinery, together with carbon repartitioning in carbohydrates and lipids.

Identification of Differentially Expressed Genes Induced by Ammonium Nitrogen in Rice Using mRNA Differential Display

RNAs isolated from ammonium- and nitrate-treated rice leaves were used to screen differentially expressed genes through mRNA differential display. A total of 72 bands appeared significant differences and some of them were further confirmed by reverse Northern and Northern blot. The results showed that two genes, A-02 （Oryza sativa drought stress related mRNA） and A-03 （Zea mays partial mRNA for TFIIB-related protein） were highly up-regulated in the ammonium-fed rice leaves. The enzyme assays showed that the activities of the two anti-oxidative enzymes, catalase and peroxidase, and the content of a non-enzymic antioxidant, glutathione, were significantly higher in the ammonium-fed rice leaves than those in the nitrate-fed ones, indicating that the ammonium nutrition might be beneficial for rice plants to improve the stress resistance during growth and development.

Pathophysiology of Cerebral Ischemia: Role of Oxidative/Nitrosative Stress

Stroke is a devastating disease with a complex pathophysiology;it ranks second to ischemic heart disease as a cause of death and long-term disability. Tissue damage results from diverse mechanisms with central involvement of free radicals’ overproduction that results in oxidative stress and hence contributes to brain damage. Free radicals [Reactive oxygen species/Reactive nitrogen species] play central a role in the diverse normal physiological processes and as defense mechanisms against harmful substances. When the rate of their production exceeds the anti-oxidant capacity of the body, oxidative stress occurs. Oxidative stress is implicated in the pathogenesis of various diseases including hypertension, atherosclerosis, diabetes mellitus and cancer;they mediate damage to cell structures, lipid peroxidation, protein denaturation, nucleic acid and DNA damage.

Nitrogen-Fixing Inhibition by KCl in A Blue-Green Alga Anabaena cylindrica

Growing in the medium containing 0.10 mol/L KCl for three days, the nitrogen-fixing activity ofAnabaena cylindrica decreased by 95%. Extent of the inhibition was enchanced with increased KCl concentrations. The biggest decrease of nitrogen-fixing activity was between 0.02–0.05 mol/L KCl. The same decline on growth was between 0.05–0.10 mol/L KCl. The longer treating-time was, the lower nitrogen-fixing activity was. A short time of KCl-treatment (for 4 h) resulted in 66.4%decrease of the activity. Under effecting of KCl for three days, the frequency of heterocyst differentiation decreased from 7.2%to 2.1%.

基于RNA-Seq筛选高粱低氮胁迫相关候选基因

研究低氮胁迫条件下不同高粱材料间的基因差异表达,为耐低氮型高粱品种选育和耐低氮胁迫的分子机制探究提供参考。选取2个耐低氮型高粱(BSX44和BTx378)为试验材料,设置正常和低氮胁迫2个处理,利用RNA-Seq技术对高粱苗期、抽穗期和开花期的基因表达进行分析,通过生物信息学对差异基因的生物学功能和代谢途径进行研究,筛选可能参与低氮调控的基因,了解氮高效基因型在氮素吸收利用过程中可能的分子途径。结果表明,在正常和低氮胁迫下,BTx378和BSX44在苗期分别筛选出937个和787个差异表达基因,抽穗期分别筛选出1305个和935个差异表达基因,开花期分别筛选出1402个和963个差异表达基因。对3个时期的差异表达基因进行鉴定,发现在苗期、抽穗期和开花期分别有246、371和306个基因在2个耐低氮高粱品种中共同差异表达,有28个基因在2个耐低氮品种的不同生育时期均差异表达,其中有5个基因上调表达,23个基因下调表达;对共同差异表达基因的KEGG相关代谢通路富集分析,发现主要集中在氮代谢、丙氨酸,天冬氨酸和谷氨酸代谢、甘油磷脂代谢、氨基酸的生物合成等途径,表明耐低氮型高粱可能通过这些途径相关基因的表达影响其对低氮胁迫的耐受性。