茉莉酸对镉胁迫下玉米幼苗叶片生理特性的影响

采用溶液培养方法,研究茉莉酸对玉米幼苗叶片抗镉性的影响。结果表明,镉胁迫显著提高玉米叶片丙二醛(MDA)、H_2O_2含量和超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽转移酶(GST)、谷胱甘肽过氧化物酶(GPX)活性,降低过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)活性,降低叶绿素a、叶绿素b和类胡萝卜素含量及生物量。与单独镉胁迫相比,外源茉莉酸处理可显著提高镉胁迫下叶片CAT、POD、APX和GR活性,显著提高叶绿素a、叶绿素b和类胡萝卜素含量及生物量,显著降低镉胁迫下叶片MDA和H_2O_2含量,从而缓解其造成的伤害。结果表明,外源茉莉酸可明显提高玉米幼苗叶片的抗氧化能力和光合色素含量,从而增加生物量的积累,缓解镉胁迫造成的伤害。     

钙对铬胁迫下玉米幼苗生长及生理特性的影响

采用含有CrCl3及CaCl2的培养液培养,研究了不同浓度钙和铬处理对玉米幼苗的叶片、株高、根长、鲜重、含水量、叶绿素、保护酶系统(SOD、POD、CAT活性)以及丙二醛(MDA)含量的影响。结果表明,单一铬处理,随着铬浓度增加,玉米植株生长明显受到抑制,株高、根长、鲜重、含水量、叶绿素含量以及CAT活性下降,SOD、POD活性上升,MDA含量增加。单一钙处理,当浓度小于160 mg/L时,明显促进植株生长,株高、根长、鲜重、含水量、叶绿素含量增加,CAT活性上升,POD活性和MDA含量下降;当钙浓度大于160 mg/L时促进效果则开始下降。钙、铬混合处理,一定浓度的钙有抑制或者缓解铬毒害的作用,减轻铬胁迫对株高、根长、鲜重和含水量的抑制,提高叶绿素含量和CAT活性,降低SOD、POD活性和MDA含量。     

碱胁迫下燕麦幼苗对外源过氧化氢的生理响应

为探讨过氧化氢(H_2O_2)对碱胁迫下植物的生理调节作用,以燕麦品种定莜6号的幼苗为材料,采用沙培方法,设置0、50和150μmol·L~(-1)三个H_2O_2浓度水平,研究了外源H_2O_2对100mmol·L~(-1) NaHCO_3胁迫下燕麦叶片活性氧代谢、渗透溶质积累和幼苗生长的影响。结果表明,NaHCO_3胁迫下,与不添加H_2O_2处理(0μmol·L~(-1))相比,50和150μmol·L~(-1) H_2O_2处理均不同程度降低了燕麦叶片超氧阴离子、H_2O_2、丙二醛、可溶性糖含量和细胞质膜的相对透性,明显提高可溶性蛋白质、脯氨酸和类胡萝卜素含量及叶绿素a/b值。NaHCO_3胁迫下,50μmol·L~(-1) H_2O_2处理的燕麦叶片超氧化物歧化酶(SOD)活性和谷胱甘肽(GSH)含量下降,过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)活性及抗坏血酸(AsA)含量提高;150μmol·L~(-1) H_2O_2处理则提高了SOD、POD、APX活性和AsA含量,降低了CAT活性,对GSH含量无明显影响。50μmol·L~(-1) H_2O_2显著缓解了NaHCO_3胁迫对燕麦幼苗生长的抑制作用,150μmol·L~(-1) H_2O_2的缓解效应不明显。     

干旱胁迫下NO对水稻日本晴叶片生理特性的影响

研究干旱胁迫下一氧化氮(Nitric oxide,NO)对水稻叶片光合速率、相对含水量及抗氧化系统的影响,旨在揭示NO增强水稻耐旱性的作用机制。以常规粳稻日本晴为材料,在土培条件下于水稻分蘖盛期叶面喷施硝普钠(SNP,NO缓释剂)和/或cPTIO(NO清除剂)后进行干旱处理,6d后,取样并分析叶片各生理指标。结果表明,与清水对照相比,干旱胁迫下,喷施100μmol/L SNP可显著增强水稻耐旱性,叶片表现出较高的相对含水量和光合速率,较低的丙二醛和过氧化氢含量。相反,100μmol/L cPTIO处理的水稻叶片光合速率明显低于对照,相对含水量略低于对照,而丙二醛和过氧化氢含量显著高于清水对照。进一步研究表明,干旱胁迫下喷施外源SNP的叶片具有较高的超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性,较低的抗坏血酸(AsA)含量和总谷胱甘肽(GSH+GSSH)含量。此外,外源喷施SNP对水稻叶片过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性影响不大,各处理间差异不显著。总之,以100μmol/L SNP作为NO缓释剂处理的水稻干旱损伤较轻,干旱胁迫下叶片具有较高的SOD及CAT活性,这可能是NO增强水稻耐旱性的主要原因。     

低温胁迫下冠菌素对玉米幼苗生理特性的调控

以玉米自交系Kr701为试验材料,叶面喷施5个不同浓度的冠菌素(COR),对照为清水,于4℃低温胁迫下培养48 h后取材,研究冠菌素(COR)对低温胁迫下玉米幼苗株高、干鲜重、相对电导率、可溶性蛋白、脯氨酸、相对含水量、SOD(超氧化物歧化酶)、POD(过氧化物酶)、APX(抗坏血酸过氧化物酶)生理生化指标的影响。结果表明,低温会抑制玉米幼苗的正常生长,各个浓度的COR处理均能促进幼苗的生长,缓解叶片相对含水量的降低和电解质的外渗,增加渗透调节物质的含量和抗氧化酶(SOD、POD、APX)的活性,增强活性氧清除能力,以0.01μmol/L处理效果最显著。喷施适宜浓度的COR能通过调控玉米幼苗各个生理生化指标来增强其抗冷性,从而缓解低温对幼苗所造成的伤害。     

镧对镉胁迫下大豆幼苗 光合作用和活性氧代谢的影响

在盆栽条件下,研究了不同浓度的La对30μmol/L和50μmol/L Cd胁迫下的大豆幼苗生理效应。结果 表明,适量的La能在一定程度上缓解Cd胁迫所导致的叶绿素含量、叶绿体可溶性蛋白质含量、光合速率、叶绿体 Mg2 + - ATPase活性的降低;能有效增强或保护叶片抗氧化能力,降低超氧阴离子自由基(O2 · )产生速率、组织自动 氧化速率和H2O2 含量,防止膜透性的增加;适量的La能保持大豆叶片中超氧化物歧化酶( SOD)和抗坏血酸过氧 化物酶(AsA - POD)活性的相对稳定,维持活性氧的代谢平衡。La对30μmol /L Cd胁迫的缓解能力较强,而对 50μmol/L Cd胁迫的缓解能力较弱。La的最佳作用浓度为0. 30μmol/L,高于0. 50μmol/L的La则加剧Cd的毒害。     

外源钙对镍胁迫下水稻幼苗抗氧化酶活性及膜脂过氧化的影响

研究了外源钙（Ca2+）对镍胁迫下水稻叶片组织超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）和抗坏血酸过氧化物酶（APX）的活性、H2O2和丙二醛（MDA）含量以及质膜电解质渗透的影响,以探讨钙缓解植物镍毒性的生理机制。0.1 mmol/L镍（Ni2+）胁迫下水稻叶片组织SOD、CAT和APX活性明显下降,POD活性明显上升,H2O2和MDA含量、电解质渗漏率显著增大,说明镍诱导了细胞发生明显的氧化损伤和膜脂过氧化;钙提高了镍胁迫下叶片组织中SOD、CAT、POD和APX活性,显著降低了H2O2、MDA含量和电解质渗漏率,且10 mmol/L Ca2+处理的抗氧化酶活性上升的程度和H2O2、MDA含量和电解质渗漏率下降的程度比5 mmol/L Ca2+处理的大。提示钙通过促进镍胁迫下水稻叶片组织抗氧化酶活性,增强活性氧清除能力,维持细胞膜结构的稳定,是钙减轻镍对水稻毒性的生理机制之一。     

垄作覆盖对夏玉米生长后期叶片衰老的影响

在华北地区一年两熟雨养农作区,研究了垄作覆盖、垄作、平作覆盖、平作4种处理对夏玉米生育后期叶片衰老的生理效应。结果表明,夏玉米吐丝后,超氧化物酶(SOD)活性逐渐降低,丙二酫(MDA)含量渐渐升高,叶绿素含量在吐丝后10 d开始下降。垄作覆盖的SOD酶活性、叶绿素含量最高,MDA的含量最低。垄作覆盖能够延缓叶片的衰老,维持叶片后期较高的生理功能。垄作覆盖处理比垄作、平作覆盖、平作处理分别增产10.26%、4.24%、13.34%。     

外源NO对低温胁迫下龙眼幼苗生理特性的影响

研究外源一氧化氮(NO)对5℃低温胁迫下龙眼幼苗生理特性的影响。结果表明:低温胁迫下,龙眼幼苗叶片中的SOD、POD和CAT活性降低,叶绿素、可溶性糖和蛋白质含量下降,丙二醛含量升高。喷施硝普钠(SNP、NO供体)显著提高龙眼幼苗的叶绿素、可溶性糖和蛋白质含量,提高净光合速率,增强SOD、POD和CAT活性,降低丙二醛含量和电解质渗透率;其中150μmol/L SNP处理效果最好。可见,外源NO通过刺激抗氧化酶活性来清除活性氧,减轻膜脂过氧化作用,缓解低温胁迫对龙眼幼苗的伤害作用,提高龙眼的抗低温胁迫能力。     

外源H2S对盐碱胁迫下裸燕麦幼苗生长和生理特性的影响

为探讨外源H_2S缓解植物盐碱胁迫伤害的生理机制及适宜喷施浓度,以裸燕麦为材料,采用盆栽砂培方法,在根部浇灌50 mmol·L~(-1)盐碱混合溶液(NaCl︰Na_2SO_4︰NaHCO_3︰Na_2CO_3=12︰8︰9︰1),同时叶面喷施不同浓度H_2S供体NaHS(0、25、50、100、200、400μmol·L~(-1)),分析了盐碱胁迫条件下外源H_2S对幼苗生长及叶片内源H_2S和光合色素含量、活性氧代谢和渗透物质积累的影响。结果表明,盐碱胁迫下裸燕麦幼苗叶片L-半胱氨酸脱巯基酶活性和H_2S含量均随NaHS喷施浓度的增大而显著提高;喷施25～100μmol·L~(-1) NaHS能够缓解盐碱胁迫对裸燕麦幼苗生长的抑制,喷施200～400μmol·L~(-1) NaHS时幼苗生长受抑加重。喷施25～400μmol·L~(-1) NaHS均不同程度提高了盐碱胁迫下裸燕麦叶片叶绿素、类胡萝卜素和谷胱甘肽含量,对抗坏血酸和可溶性蛋白质含量影响不大,使超氧阴离子、过氧化氢、丙二醛含量和质膜相对透性显著降低或变化不显著;25～200μmol·L~(-1) NaHS处理下超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性均不同程度提高,过氧化物酶(POD)活性和游离氨基酸含量显著下降或变化不显著,400μmol·L~(-1) NaHS处理降低了SOD、CAT、APX和POD活性及游离氨基酸、脯氨酸含量;25μmol·L~(-1) NaHS处理显著降低了可溶性糖含量,50～400μmol·L~(-1) NaHS处理的可溶性糖含量不同程度提高。隶属函数综合评价显示,喷施25～200μmol·L~(-1) NaHS提高了盐碱混合胁迫下裸燕麦幼苗的综合评价值(D),400μmol·L~(-1) NaHS处理的D值显著下降。综合以上结果,喷施适宜浓度NaHS(25～100μmol·L~(-1))可通过调节活性氧代谢和渗透溶质脯氨酸和可溶性糖积累缓解盐碱胁迫造成的氧化伤害和生长抑制,从而增强裸燕麦对盐碱胁迫的耐性。     

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.     

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.     

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.     

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.     

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).     

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).     

Pharmacokinetics of Marine-Derived Drugs

Marine organisms represent an excellent source of innovative compounds that have the potential for the development of new drugs. The pharmacokinetics of marine drugs has attracted increasing interest in recent decades due to its effective and potential contribution to the selection of rational dosage recommendations and the optimal use of the therapeutic arsenal. In general, pharmacokinetics studies how drugs change after administration via the processes of absorption, distribution, metabolism, and excretion (ADME). This review provides a summary of the pharmacokinetics studies of marine-derived active compounds, with a particular focus on their ADME. The pharmacokinetics of compounds derived from algae, crustaceans, sea cucumber, fungus, sea urchins, sponges, mollusks, tunicate, and bryozoan is discussed, and the pharmacokinetics data in human experiments are analyzed. In-depth characterization using pharmacokinetics is useful for obtaining information for understanding the molecular basis of pharmacological activity, for correct doses and treatment schemes selection, and for more effective drug application. Thus, an increase in pharmacokinetic research on marine-derived compounds is expected in the near future.