高AC水稻淀粉合成相关酶基因表达的温度效应

以高直链淀粉含量(AC)早籼稻品种嘉育353为材料,利用人工气候箱设置高温(日均温32℃)和适温(日均温22℃)2个温度处理,采用实时荧光定量PCR技术分析了不同灌浆温度下水稻胚乳中3个淀粉分支酶基因(sbe1、sbe3和sbe4)、3个淀粉脱支酶基因(R酶基因、isa1和isa2)以及2个淀粉合酶(GBSSⅠ和SSSⅠ)基因的表达特性。结果显示,除了sbe4、isa1和GBSSⅠ基因外,其余基因高温下表达量均显著高于适温,表明sbe1、sbe3、R酶基因、isa2以及SSSⅠ基因属于温度敏感型基因,可能在水稻胚乳淀粉合成的温度调控方面起着关键作用。     

小麦淀粉合酶基因家族成员的表达差异分析

籽粒淀粉的含量和结构影响小麦的产量和品质,而淀粉合酶在淀粉合成中起着关键作用。植物淀粉合酶基因经多次复制和功能分化,形成了具有不同功能特性的多成员大家族。为揭示淀粉合酶基因家族成员间的序列特性和表达差异,本研究参考已知的水稻淀粉合酶蛋白序列,对小麦全基因组中的淀粉合酶基因进行鉴定,并对其进行差异表达分析。结果共鉴定到27个小麦淀粉合酶基因,这些基因分布在1A/1B/1D、2A/2B/2D、6A/6B/6D、7A/7B/7D染色体上,可分为Group A和Group B两大类,Group A包含TaGBSS、 TaSSⅠ、 TaSSⅡ三个亚家族,所编码的蛋白均具有motif1～motif10,且motif排列顺序一致;Group B包含 TaSSⅢ、 TaSSⅣ两个亚家族,所编码的蛋白都缺少motif9和motif10,另外TaSSⅢ亚家族还缺少motif8。与玉米、水稻、高粱、拟南芥不同,小麦淀粉合酶基因没有 TaSSⅤ亚家族。同一亚家族内不同基因具有明显的表达差异,其中, TaGBSSⅠ、 TaSSⅡa和 TaSSⅢa在胚乳中特异表达;小麦相同部分同源群内的淀粉合酶基因间在不同组织和...     

玉米淀粉分支酶sbeⅡb基因启动子的克隆和表达载体构建

以玉米基因组DNA为模板,通过LA-PCR技术扩增了玉米淀粉分支酶sbeⅡb基因启动子序列,并将其克隆到pMD18-TVector上,对重组子进行PCR检测和限制性内切酶分析并测序。结果表明,该启动子和Genbank中发表的玉米淀粉分支酶sbeⅡb基因启动子同源性达98.52%,克隆片段长为934bp。再将经BamHⅠ和HindⅢ双酶切得到的启动子片段克隆到相同酶酶切的pBI121载体上,构建植物表达载体pBI121-sbeⅡb,并进行酶切鉴定和PCR检测。结果显示,启动子基因sbeⅡb已成功整合到植物表达载体pBI121上。序列中发现高等植物启动子所特有的基本核心序列和种子特异表达所需的特殊调控元件。     

白粉病对小麦品种西农979籽粒淀粉合成关键酶基因表达的影响

为了揭示白粉病对花后小麦籽粒淀粉合成的影响机制,以小麦品种西农979为材料,利用实时荧光定量PCR技术研究白粉病不同发病程度对小麦籽粒淀粉合成相关酶基因表达的影响。结果表明,随着感病程度的增加,小麦籽粒的腺苷二磷酸葡萄糖焦磷酸化酶基因AGPase、淀粉分支酶基因SBE和可溶性淀粉合成酶基因SSS的表达均被抑制,其酶活性下降;束缚态淀粉合成酶I基因GBSSⅠ的表达量和酶活性均高于对照;去分支酶基因DBE的表达量与对照相比没有明显变化,但其酶活性在病害高峰期高于对照;支链淀粉含量和总淀粉含量显著降低,而直链淀粉含量增加。由此可知,白粉病通过改变籽粒淀粉合成相关酶基因的表达及活性而影响淀粉的积累。     

小麦淀粉合成关键酶基因和相关蛋白表达对不同施磷量的响应

为深入研究磷素在小麦淀粉产量和品质形成过程中的作用,以新疆冬小麦主栽品种新冬20号为试验材料,研究0 kg·hm^-2（CK）、105 kg·hm^-2（LP）和210 kg·hm^-2（HP）3种施磷（P₂O₅）量对小麦籽粒灌浆特性、淀粉合成关键酶(AGPase和GBSS)活性和基因表达、胚乳可溶性蛋白和淀粉粒结合蛋白含量及谱带特征、胚乳微观特性等的影响。结果表明,籽粒灌浆后期磷肥对粒重的促进作用逐渐增强;低磷（LP）条件下, agp1、 agp2、 gbss1、 gbss2基因表达量显著提高;3个处理下AGPase活性的变化趋势基本一致;籽粒灌浆中期（14～21 d）,低磷处理的GBSS活性显著高于CK;不同磷处理对淀粉粒结合蛋白和胚乳可溶性蛋白含量的影响显著,但对蛋白谱带特征的影响较弱。扫描电镜结果显示,不同磷处理的胚乳淀粉粒形态未发生明显变化;与CK和高磷（HP）处理相比,低磷处理下籽粒胚乳横断面蛋白基质较少,淀粉粒与蛋白质结合较疏松。说明常规施磷（低磷）条件下,淀粉合成关键酶基因（agp和gbss）相对表达量提高或酶活性变化可影响籽粒淀粉合成及胚乳中蛋白与淀粉粒的嵌合度,并最终造成粒重的增加和淀粉特性的变化。     

磷素对小麦籽粒支链淀粉合成及其链长分布的影响

为探究不同磷水平对小麦籽粒支链淀粉合成与支链淀粉精细结构的影响。以新冬20号（南疆主栽）和新冬23号（北疆强筋面包小麦）为材料,研究了3种施磷(P₂O₅)量 0 kg·hm^-2（CK ）、105 kg·hm^-2（CP ）和210 kg·hm^-2（HP）对小麦籽粒支链淀粉合成相关酶基因表达、相关酶活性、籽粒支链淀粉含量、支链淀粉链长分布以及籽粒全磷含量的影响。结果表明,施磷显著提高了支链淀粉合成相关酶基因（ sbe1、 sbe2a、 sbe2b、 iso1）的表达量和籽粒支链淀粉含量。CP处理提高了支链淀粉B链段的比例,但降低了A链段的比例。两个参试小麦品种籽粒中支链淀粉合成关键酶的活性对磷素的敏感性不同,新冬 20号受磷水平影响较大。施磷提高了新冬20号胚乳中蔗糖合成酶（SS）活性和酶活高峰期的淀粉分支酶（SBE）活性,提前了新冬20号胚乳中淀粉去分支酶（DBE）活性峰值的出现时间。     

颗粒结合型淀粉合成酶研究进展

本文综述了小麦胚乳中合成直链淀粉的关键酶——颗粒结合型淀粉合成酶(GBSS)的研究进展，展望了GBSS的研究前景。小麦中的GBSS基因在种子中特异表达；控制3个Waxy，位点的基因Wx—A1、Wx—B1和Wx—D1，分别位于7AS、4AL和7DS上；六倍体小麦和二倍体小麦中3个GBSS的DNA序列从起始密码子到终止密码子，Wx—A1为2781bp，Wx-B1为2794bp，Wx—D1为2862bp。基因的完全编码区含有11个外显子和10个内含子，在核苷酸序列上三个糯基因彼此之间有惊人的同源性；研究表明，直链淀粉含量和淀粉糊化特性受Wx—B1的影响最大，其次是Wx-D1缺失蛋白，Wx-A1缺失蛋白的影响最小。GBSS的鉴定技术包括I2—KI染色、电泳和分子标记技术鉴定。     

花后高温胁迫对春小麦籽粒淀粉合成的影响

为揭示高温胁迫对春小麦籽粒淀粉合成的影响机制,以宁春4号小麦为材料,分别于花后5、10、15和20 d进行高温（35 ℃±3 ℃）胁迫,利用实时荧光定量PCR法（qPCR）研究花后不同时期高温胁迫下小麦籽粒淀粉合成相关酶基因表达,并将基因表达量与对应籽粒淀粉合成酶活性进行相关性分析。结果表明,束缚态淀粉合成酶Ⅰ（GBSSⅠ）基因对高温不敏感,而腺苷二磷酸葡萄糖焦磷酸化酶（AGPase）基因、淀粉分支酶（SBE）基因、可溶性淀粉合成酶（SSS）基因的表达均被高温胁迫抑制;被测的4种淀粉合成相关酶的活性均被高温协迫抑制。自然生长温度下,除GBSSⅠ酶外,SBE、AGPase和SSS酶活性与其对应基因的表达量极显著或显著正相关;高温胁迫使4种被测的淀粉合成相关酶活性与其对应基因表达量的相关性降低。高温胁迫通过抑制小麦籽粒淀粉合成相关酶基因的表达而影响对应酶活性,使小麦籽粒淀粉的积累发生改变;高温胁迫发生时间越早,对小麦籽粒淀粉积累影响越大。     

玉米ae基因的研究进展

ae基因是一种胚乳突变基因。玉米ae突变体的表现型为玻璃状、无光泽胚乳。ae基因编码淀粉分枝酶Ⅱb(SBEⅡb)是SBEⅡb的结构基因,ae基因定位在玉米第5条染色体长臂上,在玉米中是单拷贝基因。在ae突变体胚乳中,SBEⅡb的活性缺失,子粒的表观直链淀粉含量增加,同时支链淀粉的α-l,6糖苷键分支点的数量降低。本文对ae基因的结构、功能、特性等作了一个较全面的综述,对其做更深入的研究,以改良淀粉品质。     

糯小麦（Waxy Wheat）研究进展

糯小麦因下含直链淀粉或直链淀粉含量很低,所有在食品工业和非食品工业上将会有重要的应用价值。然而,在自然条件下六倍体小麦中则无全糯质小麦存在,需要人工创造。近几年来,国际上仅出现了糯小麦研究的热潮,而且进展较快。六倍体小麦的糯质特性由３个基因位点（Ｗｘ－Ａ１、Ｗｘ－Ｂ１、Ｗｘ－Ｄ１）控制,分别位于７Ａ、４Ａ、７Ｄ染色体上,３个基因组合成８种Ｗａｘｙ类型,用ＳＤＳ－ＰＡＧＥ电泳分析可加以区别。当３个位     

Comparative Assessment of the Efficacy of Various Nitrogen Fertilizers

Summary

The efficiency of N fertilizers is usually poor; often less than 50% of the applied N is taken up by the crop. This review focuses on various N fertilizers with respect to the significance of different N loss pathways, namely (i) ammonia volatilization, (ii) dinitrogen and nitrogen oxide emissions, and (iii) nitrate leaching. Further, the significance of biological N immobilization, ammonium fixation and, finally, the impact of nitrate vs. ammonium uptake on crop yield are also discussed. The reviewed literature shows that N fertilizers may differ markedly in their susceptibility to losses. There is, however, considerable scope to improve N efficiency of each N source by proper N management practices.     

Studies on natural repellents against potato tuber moth (Phthorimaea operculella Zeller) in country stores

Summary The effects of the leaves of five plant species, one from each of the generaAmbrosia, Anemone, Eupatorium, Eucalyptus andLantana, on potato tuber moth were investigated under indigenous storage conditions at the Central Potato Research Station, Shillong (1800 m above sea level). Their action was compared with that of a biological insecticide (spores ofBacillus thuringiensis), a chemical insecticide (carbaryl), and an untreated control. The data collected after six months storage on tuber damage, sprout damage and the rotting indicated that the leaves ofLantana aculeata provided most protection to the tubers, reducing damage from over 70% in the check to below 5%, and sprout damage from over 45% to below 3%. Next best wasEucalyptus globulus followed byB. thuringiensis. They may be used on tubers stored for table use or for seed as they had no adverse effect on germination or on the yield of a subsequent crop.     

Novel food and non-food uses for sorghum and millets

Sorghum and millets have considerable potential in foods and beverages. As they are gluten-free they are suitable for coeliacs. Sorghum is also a potentially important source of nutraceuticals such antioxidant phenolics and cholesterol-lowering waxes. Cakes, cookies, pasta, a parboiled rice-like product and snack foods have been successfully produced from sorghum and, in some cases, millets. Wheat-free sorghum or millet bread remains the main challenge. Additives such as native and pre-gelatinised starches, hydrocolloids, fat, egg and rye pentosans improve bread quality. However, specific volumes are lower than those for wheat bread or gluten-free breads based on pure starches, and in many cases, breads tend to stale faster. Lager and stout beers with sorghum are brewed commercially. Sorghum's high-starch gelatinisation temperature and low beta-amylase activity remain problems with regard to complete substitution of barley malt with sorghum malt . The role of the sorghum endosperm matrix protein and cell wall components in limiting extract is a research focus. Brewing with millets is still at an experimental stage. Sorghum could be important for bioethanol and other bio-industrial products. Bioethanol research has focused on improving the economics of the process through cultivar selection, method development for low-quality grain and pre-processing to recover valuable by-products. Potential by-products such as the kafirin prolamin proteins and the pericarp wax have potential as bioplastic films and coatings for foods, primarily due to their hydrophobicity.     

In vitro antimicrobial activity of different accessions ofSolanum commersonii Dun. from Uruguay

Summary The in vitro antimicrobial activity of extracts from accessions ofSolanum commersonii Dun. collected in the south of Uruguay was investigated against five microorganisms including the pathogenRalstonia solanacearum. A total of 30 extracts corresponding to organic and aqueous extracts were studied. Interestingly, most of the positive results for growth inhibition were againstR. solanacearum. The extracts were also analyzed for the presence of glycoalkaloids and lectins. Six of the ten aqueous extracts showed lectin presence and a wide variation in the type and amounts of glycoalkaloids, was found. Results indicate that there is no clear relationship between the antimicrobial activity against the five microorganisms screened and the presence or amounts of lectins and glycoalkaloids, traditionally regarded as possible antimicrobial metabolites in theSolanum genus, which indicates the presence of as yet unidentified antimicrobial compounds.     

Extreme resistance to infection by potato virus X in genotypes of wild tuber-bearingSolanum species

Summary Clones derived from thirty-one different accessions (nineteen of Argentine origin) belonging to eightSolanum species were screened for resistance to infection by potato virus X strain cp (PVX cp) by mechanical inoculation of plantlets that had been micropropagated in vitro. Estimates of PVX multiplication obtained by enzyme linked immunosorbent assay and slot blot nucleic acid hybridization allowed the identification of resistant clones derived from five accessions belonging toS. commersonii S. oplocense, S. sparsipilum andS. tuberosum andigena. Resistant genotypes supported PVX concentrations 5 to 15 times smaller than did the susceptible control cultivar Spunta. Graft inoculation test confirmed the presence of extreme resistance similar to that conferred by the ‘immunity’ gene X¹ (also called RX_act).     

Cyanobacteria Secondary Metabolites as Biotechnological Ingredients in Natural Anti-Aging Cosmetics: Potential to Overcome Hyperpigmentation,Loss of Skin Density and UV Radiation-Deleterious Effects

The loss of density and elasticity, the appearance of wrinkles and hyperpigmentation are among the first noticeable signs of skin aging. Beyond UV radiation and oxidative stress, matrix metalloproteinases (MMPs) assume a preponderant role in the process, since their deregulation results in the degradation of most extracellular matrix components. In this survey, four cyanobacteria strains were explored for their capacity to produce secondary metabolites with biotechnological potential for use in anti-aging formulations. Leptolyngbya boryana LEGE 15486 and Cephalothrix lacustris LEGE 15493 from freshwater ecosystems, and Leptolyngbya cf. ectocarpi LEGE 11479 and Nodosilinea nodulosa LEGE 06104 from marine habitats were sequentially extracted with acetone and water, and extracts were analyzed for their toxicity in cell lines with key roles in the skin context (HaCAT, 3T3L1, and hCMEC). The non-toxic extracts were chemically characterized in terms of proteins, carotenoids, phenols, and chlorophyll a, and their anti-aging potential was explored through their ability to scavenge the physiological free radical superoxide anion radical (O₂^•−), to reduce the activity of the MMPs elastase and hyaluronidase, to inhibit tyrosinase and thus avoid melanin production, and to block UV-B radiation (sun protection factor, SPF). Leptolyngbya species stood out for anti-aging purposes: L. boryana LEGE 15486 presented a remarkable SPF of 19 (at 200 µg/mL), being among the best species regarding O₂^•− scavenging, (IC₅₀ = 99.50 µg/mL) and also being able to inhibit tyrosinase (IC₂₅ = 784 µg/mL), proving to be promising against UV-induced skin-aging; L. ectocarpi LEGE 11479 was more efficient in inhibiting MMPs (hyaluronidase, IC₅₀ = 863 µg/mL; elastase, IC₅₀ = 391 µg/mL), thus being the choice to retard dermal density loss. Principal component analysis (PCA) of the data allowed the grouping of extracts into three groups, according to their chemical composition; the correlation of carotenoids and chlorophyll a with MMPs activity (p < 0.01), O₂^•− scavenging with phenolic compounds (p < 0.01), and phycocyanin and allophycocyanin with SPF, pointing to these compounds in particular as responsible for UV-B blockage. This original survey explores, for the first time, the biotechnological potential of these cyanobacteria strains in the field of skin aging, demonstrating the promising, innovative, and multifactorial nature of these microorganisms.     

Marine Pharmacology in 2009–2011: Marine Compounds with Antibacterial,Antidiabetic, Antifungal,Anti-Inflammatory,Antiprotozoal, Antituberculosis,and Antiviral Activities; Affecting the Immune and Nervous Systems,and other Miscellaneous Mechanisms of Action ?

The peer-reviewed marine pharmacology literature from 2009 to 2011 is presented in this review, following the format used in the 1998–2008 reviews of this series. The pharmacology of structurally-characterized compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral pharmacological activities were reported for 102 marine natural products. Additionally, 60 marine compounds were observed to affect the immune and nervous system as well as possess antidiabetic and anti-inflammatory effects. Finally, 68 marine metabolites were shown to interact with a variety of receptors and molecular targets, and thus will probably contribute to multiple pharmacological classes upon further mechanism of action studies. Marine pharmacology during 2009–2011 remained a global enterprise, with researchers from 35 countries, and the United States, contributing to the preclinical pharmacology of 262 marine compounds which are part of the preclinical pharmaceutical pipeline. Continued pharmacological research with marine natural products will contribute to enhance the marine pharmaceutical clinical pipeline, which in 2013 consisted of 17 marine natural products, analogs or derivatives targeting a limited number of disease categories.     

Recent Modifications of Chitosan for Adsorption Applications: A Critical and Systematic Review

Chitosan is considered to be one of the most promising and applicable materials in adsorption applications. The existence of amino and hydroxyl groups in its molecules contributes to many possible adsorption interactions between chitosan and pollutants (dyes, metals, ions, phenols, pharmaceuticals/drugs, pesticides, herbicides, etc.). These functional groups can help in establishing positions for modification. Based on the learning from previously published works in literature, researchers have achieved a modification of chitosan with a number of different functional groups. This work summarizes the published works of the last three years (2012–2014) regarding the modification reactions of chitosans (grafting, cross-linking, etc.) and their application to adsorption of different environmental pollutants (in liquid-phase).