多不饱和脂肪酸与红冬孢酵母低温适应性的关系研究

以一株产油酵母——红冬孢酵母(Rhodosporidium kratochvilovae)YM25235作为出发菌株,分析其低温生长适应性与细胞膜流动性、膜脂脂肪酸含量的变化和多不饱和脂肪酸合成关键基因——Δ12-脂肪酸脱氢酶基因mRNA表达水平的关系.结果显示,YM25235在5～35 ℃温度条件下均能生长,最适生长温度为30 ℃.低温条件下细胞膜流动性明显降低,但是多不饱和脂肪酸质量分数由从30 ℃时的24.35%增加到15 ℃时的40.32%,而且15 ℃时Δ12-脂肪酸脱氢酶基因mRNA水平提高了3.4倍.结果说明低温条件下细胞膜流动性下降,导致多不饱和脂肪酸合成相关基因表达水平提高,使得细胞膜脂中多不饱和脂肪酸含量增加,促进了菌株低温生长适应性.     

Effects of free sterols on the fluidity of polar lipids in rice dry embryo

Free sterols from rice dry embryo reduce the onset phase transition temperature and widen the transition range of total polar lipids and phosphatidylglycerol, which increases the membrane fluidity below their phase transition temperature and decreases the fluidity of membranes above their phase transition temperature. And 50% of free sterols result in a complete disappearance of phase transition. The fluidity of other main components of polar lipids is decreased by free sterols above 0℃. The results confirm that free sterols can modulate membrane lipid fluidity.     

植物脂肪酸及其衍生物防御信号研究进展

植物由于不能移动而发展了复杂而精密的抗病系统.近年来,人们发现作为细胞膜组分的脂肪酸在植物的各种抗病机制中发挥着举足轻重的作用.脂肪酸及其衍生物不仅参与植物基础免疫和系统免疫,还参与经典抗病基因(R基因)介导的抗病过程.目前,已发现许多与脂肪酸(尤其是16碳和18碳脂肪酸及其衍生物)代谢相关的突变体,对这些突变体抗病性改变的分子机制研究成为植物抗病领域研究热点之一.本文综述了脂肪酸及其衍生物在植物防御信号转导中的最新研究进展,旨在为植物抗病遗传育种研究提供新的参考.     

相变膨胀珍珠岩制备工艺及相变控温砂浆性能

根据低共熔相变点理论计算结果,制备月桂酸-肉豆蔻酸二元低共熔脂肪酸相变材料,以膨胀珍珠岩为无机载体,采用高温真空浸渍法制备相变骨料,并对其进行包裹,确定最佳包裹材料及掺量.通过场发射扫描电镜观测相变骨料切割截面,脂肪酸经吸附进入多孔颗粒内部,并黏附于珍珠岩孔隙内壁,经石蜡包裹后脂肪酸相变材料较稳定地处于石蜡与膨胀珍珠岩内壁包围的孔空间内.利用相变骨料制备相变控温砂浆,测试其物理力学性能及热性能.结果表明:相变珍珠岩砂浆板物理力学性能达到建筑保温砂浆标准要求,且具有较好的控温效果,随着脂肪酸掺量的增加,有效热量值降低越多,温度延时越长,降温幅度越大.     

零上低温对巴西橡胶树无性系两种酶的影响

采用聚丙烯酰胺凝胶电泳研究不同抗冷性的巴西橡胶树(Hevea brasiliensis)过氧化物酶和酯酶同工酶。试验结果表明:不论在常温或低温下,过氧化物酶同工酶在各无性系间存在明显的差异,抗冷性强的无性系比抗冷性弱的无性系多2～3条酶区带;酯酶同工酶在各无性系间也有显著差异,抗冷性强的无性系比抗冷性弱的无性系多2～7条酶区带,经低温作用后抗冷性强的无性系同工酶区带保持较稳定,而抗冷性弱的无性系3～4条酶区带消失。     

气相色谱法测定野生植物种子中的脂肪酸

为探索新的油料资源，对野生植物种子的脂肪酸组成进行了研究。以正己烷／乙醚（Ｖ／Ｖ＝４／３）作提取剂，０．４ｍｏｌ／Ｌ的氢氧化钾－甲醇溶液作甲酯化试剂，采用室温下快速酯交换法制备脂肪酸甲酯，气相色谱法测定了６种野生植物种子中的脂肪酸组成及含量。样品所含主要脂肪酸为棕榈酸、油酸、亚油酸。其中５种野生植物种子的亚油酸含量为６０．４５％～７９．９６％。与几种常见植物油的脂肪酸组成进行了对比，结果表明，被测样品的脂肪酸组成与常见植物油是类似的，但其亚油酸含量普遍高于植物油。同时还分析了几种水果子的脂肪酸含量。     

高等植物脂肪酸去饱和酶及编码基因研究进展

生物膜是细胞、细胞器与外界环境连接的界面,是温度胁迫伤害发生的原初位点。细胞膜脂不饱和脂肪酸含量和组分是影响生物膜相变的主要因素,进而影响植物在温度胁迫下的抗性。脂肪酸去饱和酶是脂肪酸代谢过程中的关键酶,调节细胞膜中脂肪酸的含量和组分。笔者根据脂肪酸去饱和酶在催化反应中的先后顺序将其分为3类,分别阐述这3类脂肪酸去饱和酶与温度胁迫下植物适应性的关系,综述了近年来国内外脂肪酸酶去饱和酶及编码基因的克隆、功能鉴定、表达调控等方面的研究进展,对应用基因工程技术培育出温度抗性较强植物品种的研究进行了展望。     

Simulation experiments for evolution of fatty acids in immature source rocks

The anhydrous, hydrous and bitumen-extrac- ted simulations were carried out for the immature source rocks from the Liaohe sag. It has been shown from the result that with increasing temperature in simulation experiments, the fatty acids content decreased at first and then increased. The decrease of fatty acids in immature rocks is presumably related to alkanes generation in immature oils, whilst the increase may be related to the fact that some additional fatty acids are generated from kerogen and the tightly bound fatty acids in kerogen are released as bound fatty acids in kerogen and unbound fatty acids in bitumen. The fact that the bitumen generated from kerogen contains fatty acids has demonstrated that some bound and tightly bound fatty acids in kerogen can be transferred into bitumen. The preferential fatty acids in the immature source rocks are found to be mono-carboxylic acids with longer chains, whilst krogen contains relatively more di-carboxylic acids. It has been found that the fatty acids in immature source rocks can be changed from that with more longer chains to that with more shorter chains when evolution extent has been increased. Based on simulation results and the fact that the majority of fatty acids in immature oils are those with longer chains, it is inferred that the contribution of fatty acids to forming alkanes in immature oils mainly takes place at the evolution stage with R₀ <0.6%. The simulation experiments have also demonstrated that H₂O could promote the generation of fatty acids with more di-carboxylic acids and delay alkanes formation from fatty acids.     

红树植物叶片中脂肪酸组成及其资源价值

采用气相色谱和色质联用仪分析发现我国不同地区主要红树植物种类叶片与非红树植物在脂肪酸组成上相似，但饱和脂肪酸含量相对较多，不饱和脂肪酸含量较少；脂肪酸不饱和指数较低；不饱和脂肪酸与饱和脂肪酸含量的比值较小．红树植物体内多不饱和脂肪酸种类多而且廿碳四烯酸和亚油酸含量较高，是潜在的脂肪酸资源．红树植物叶片凋落物中的多不饱和脂肪酸为红树林生态系统中的鱼虾蟹提供必需脂肪酸，对提高近海水产的产量有重要的意义     

重金属污染土壤的植物修复及其机理研究

近年来,作为一种成本低廉、对环境友好的修复方法,重金属污染土壤的植物修复成为环境修复领域的研究热点.早期的研究侧重于超富集植物的发现与实际应用,近来超富集植物重金属富集机理的研究得到了重视.尽管重金属植物累积的生化机制尚未能被完整阐述,但在土壤重金属生物活性、超富集植物重金属的吸收、转运、储存等方面还是取得了大量进展.综述了近年来国内外相关研究工作成果,探讨了该研究领域存在的主要问题,认为在有机鳌合剂如有机酸与氨基酸等对重金属活性、耐性和离子迁移转运系统中所起作用等方面尚需要深入研究.如果在植物重金属吸收、迁移、解毒机理及其影响因素等重金属富集的关键方面能取得进展,则将大大丰富污染土壤重金属修复的研究与应用领域.     

不同组织TA15钛合金热压缩力学行为研究

采用gleeble-1500 热模拟试验机,对TA15钛合金4种典型组织试样进行了高温准静态压缩试验,研究了不同原始组织的TA15钛合金高温压缩力学行为,不同组织对其高温准静态力学性能及温度敏感性的影响.结果表明:在同一温度下,4种组织的流变应力随温度的升高而降低,且最初流变应力随应变的增加快速增加,当流变应力达到一个峰值后,逐渐下降,最后处于稳定流变状态;不同的组织对TA15钛合金高温准静态力学性能有很大影响;600 ℃变形时,网篮组织的温度敏感性最低,固溶时效组织其次,双态组织第三,等轴晶粒组织温度敏感性最高;700~900 ℃下变形,各组织温度敏感性的排序不变,但网篮组织的温度敏感性和其它3种组织温度敏感性的差距缩小;当在超过相变温度的1000 ℃下变形时,各试样的组织完全相同,其温度敏感性不再有任何差异,其力学性能也几乎相同.     

Enzymic activation and transfer of fatty acids as acyl-adenylates in mycobacteria

The metabolic repertoire in nature is augmented by generating hybrid metabolites from a limited set of gene products. In mycobacteria, several unique complex lipids are produced by the combined action of fatty acid synthases and polyketide synthases (PKSs), although it is not clear how the covalently sequestered biosynthetic intermediates are transferred from one enzymatic complex to another. Here we show that some of the 36 annotated fadD genes, located adjacent to the PKS genes in the Mycobacterium tuberculosis genome, constitute a new class of long-chain fatty acyl-AMP ligases (FAALs). These proteins activate long-chain fatty acids as acyl-adenylates, which are then transferred to the multifunctional PKSs for further chain extension. This mode of activation and transfer of fatty acids is contrary to the previously described universal mechanism involving the formation of acyl-coenzyme A thioesters. Similar mechanisms may operate in the biosynthesis of other lipid-containing metabolites and could have implications in engineering novel hybrid products.     

酵母酒精耐性机制的研究进展

目前,酵母的酒精耐受机理还未完全清楚。在生长培养基中补充不饱和脂肪酸、维生素和蛋白质可增加酒精耐性。流加培养基的方式、胞内酒精积累、温度和渗透压等因素均与酵母的酒精耐性有关。酒精毒性的复杂性质显示,有很多不同基因可能与酒精耐性机理有关。一些遗传方法(如原生质体融合杂交)和连续培养法已用于酒精耐性酵的筛选,通过对菌株的分离和特性鉴定有助于更好的理解酒精耐性。     

Molecular characterization of GmNHX2, a Na＋/H＋ antiporter gene homolog from soybean,and its heterolosous expression to improve salt tolerance in Arabidopsis

Na＋/H＋ antiporters have been well documented to enhance plant salt tolerance by regulating cellular ion homeostasis. Here, a putative Na＋/H＋ antiporter gene homolog GmNHX2 from soybean was cloned and predicted to encode a protein of 534 amino acids with 10 putative transmembrane domains. GmNHX2 was expressed in all soybean plant tissues but enriched in roots and its expression was induced by NaCI and polyethylene glycol （PEG） treatments. GmNHX2 exhibits greater sequence similarity with LeNHX2 and AtNHX6 than that of AtNHX1 and AtSOS1. Although phylogenetic analysis clustered GmNHX2 with organellar （tonoplast and vesicles） antiporters, the GmNHX2-EGFP （enhanced green fluorescent protein） fusion protein was possibly localized in the plasma membrane or organelle membrane of transgenic plant cells, Furthermore, transgenic Arabidopsis plants expressing GmNHX2 were more tolerant to high NaCl concentrations during germination and seedling stages when compared with wild-type plants. These results suggest that GmNHX2 is a membrane Na＋/H＋ antiporter and may function to regulate ion homeostasis under salt stress.     

低温对黄瓜几种内源激素含量的影响

为明确黄瓜的耐低温性及脱落酸(ABA)、生长素(IAA)、赤霉素(GA3)、腐胺(Put)、亚精胺(Spd)、精胺(Spm)含量对其生长的影响变化规律,选取耐低温性不同的6份材料9504,9506,9507,9511,9514,9517,进行低温处理,白天12℃,晚上8℃,每天光照处理7.5 h,强度为30μmol(m2.s)-1,约合2 000 lx,共处理14 d。结果表明,在常温下各内源激素含量差异不显著,经低温处理的含量均上升,差异均显著。相关分析表明,耐寒指数与处理后的全部激素含量的偏相关均呈正相关,但均未达显著水平。说明低温使黄瓜幼苗的生长受到一定程度的抑制,但能够通过调节自身的内源激素来减轻低温的伤害,维持植物体的正常生长及生理代谢功能,从而表现出一定的耐低温潜力。     

离子液体催化制备生物柴油的试验研究

制备了一种水溶性正丁基吡啶硫酸氢盐离子液体,运用红外光谱、热重分析等方法对所制备离子液体进行表征,数据表明与预期结构相符.以该离子液体为催化剂催化小桐子油脂肪酸制备生物柴油,考察了试验反应温度、甲醇与小桐子油脂肪酸体积比、离子液体催化剂用量等因素对试验转化率的影响.结果表明在反应温度100 ℃、催化剂用量为小桐子油脂肪酸质量的6%、醇酸体积比1:1、反应时间75 min的条件下反应转化率可达96%以上.离子液体稳定性较好,循环使用6次依然保持较高的催化转化率.