Analysis of the structure of lignin-carbohydrate complexes by the specific13C tracer method

In the present study the specifically¹³C-enriched lignin precursors of biosynthesis (i.e., coniferin-[side chain–¹³C], coniferin-[side chain-–¹³C] and coniferin-[side chain-–¹³C]) were synthesized and administered exogeneously to ginkgo shoots (Ginkgo biloba L.) to obtain¹³C-enriched lignin-carbohydrate complexes (LCCs). The specifically¹³C-enriched LCCs were isolated from the newly formed xylem of ginkgo shoots administered with the¹³C-enriched precursors and degraded by enzymes. Lignin-rich fractions, so called enzyme-degraded LCCs (EDLCCs), were obtained. By determining their¹³C-NMR spectra, information related to the chemical structure of lignin building units and linkages between phenylpropane units of lignin and carbohydrates were obtained. It was found that these precursors were incorporated in natural lignin successfully. Three lignin-carbohydrates linkages (i.e., ether type, ester type, ketal type) were found at the C -position of the side chain of phenylpropane units in ginkgo LCC. No lignin-carbohydrate bond at the C- or C-position of the lignin side chain was observed in the¹³C-NMR spectra of the¹³C-enriched LCCs. This fact indicates that a specific¹³C tracer technique can be useful in NMR study of the chemical structure of LCCs.Part of this paper was presented at the 5th Pacific Polymer Conference, Kyongju, Korea, October 1997     

中棉所63棉铃对位叶光合生理性能的杂种优势研究

以杂交棉中棉所63及其亲本为材料,在棉铃发育时期对棉铃对位叶的生理和光合性能指标进行测定,探索中棉所63获得高产的杂种优势形成机理。结果表明:1)中棉所63产量优势显著。单株结铃数比两亲本分别高21.52%,43.28%,铃重高2.42%,19.31%,叶面积载铃量高22.39%,22.30%。2)中棉所63在棉铃发育后期棉铃对位叶生理指标表现出显著的杂种优势。棉铃对位叶叶面积分别比亲本高26.60%,59.41%,并且中棉所63棉铃对位叶保持较高水平的SOD活性,使其生理代谢明显提高;与此同时,中棉所63的MDA含量显著低于亲本,细胞膜受损较轻,延缓了对位叶的衰老。3)中棉所63在棉铃发育后期棉铃对位叶光合指标表现出显著的杂种优势。在棉铃发育后期,中棉所63叶绿素含量、SPS活性的高水平,能够维持高效率的光合作用,积累更多的光合产物,从而使中棉所63获得较高的单株结铃数和铃重,最终获得高产。     

禽流感防控和免疫策略分析

1概述禽流感是一个世界性难题,近年来由于它给全球养禽业乃至人类生命安全所造成的重大威胁和危害,世界动物卫生组织(OIE)将其列为对人类和动物健康具有重大威胁的疾病,引起越来越多的关注和重视。H5N1亚型高致病性禽流感自2003年在东南亚开始暴发以来,     

硬粒小麦—簇毛麦双二倍体

从(T.durum×H.villosa)F₁的自交和自由授粉后代中,获得了兼具硬粒小麦穗形和簇毛麦护颖颖脊刚毛、叶片和叶鞘边缘茸毛和对白粉病免疫等双亲性状的结实性正常的植株。经细胞学鉴定,其2n=42,在花粉母细胞减数分裂中期 I(MI)有20.5个二价体,1个左右单价体,在80%左右的花粉母细胞中有21个二价体,对其自交后代连续3年、5个世代的鉴定结果表明,上述性状已基本稳定。用染色体 N——分带技术进行带型分析的结果证明,它是一个包含有硬粒小麦 A、B 染色体组和簇毛麦 V 染色体组的硬粒小麦——簇毛麦双二倍体 AABBVV.该双二倍体株高100—110厘米,穗长9—12厘米,每穗有20—24个小穗,每穗30粒左右,千粒重25—35克,籽粒蛋白质含量20%左右,对白粉病免疫,抗锈病,感染赤霉病。将它与普通小麦(T.aestivum)杂交,F₁植株的花粉母细胞在 MI 有14个左右二价体和14个左右单价体,自交结实率仅3%左右。但用普通小麦回交,结实率可逐代提高。在回交后代群体中,已分离出对白粉病免疫的植株,是一个可望在小麦育种计划中利用的新中间型材料。     

四倍体酸枣组培苗移栽研究

以四倍体酸枣生根组培苗为试材,研究炼苗天数、基质种类、空气相对湿度、组培苗高度、根条数及移栽时间对组培苗移栽成活率和生长的影响。结果表明：移栽应在4月底至6月进行,在此时期选择高度大于5 cm,根7条以上的组培苗,经炼苗3天,移栽至纯蛭石或珍珠岩与土（1:1）或蛭石与土（1:1）中,移栽前期保持空气相对湿度在90%以上,移栽成活率可达70%以上。     

Immune responses elicited in mice with recombinant <Emphasis Type="Italic">Lactococcus lactis</Emphasis> expressing F4 fimbrial adhesin FaeG by oral immunization

Enterotoxigenic Escherichia coli (ETEC) is a major pathogenic agent causing piglet diarrhea. The major subunit and adhesin FaeG of F4⁺ ETEC is an important virulence factor with strong immunogenicity. To determine whether Lactococcus lactis (L. lactis) could effectively deliver FaeG to the mucosal immune system, recombinant L. lactis expressing FaeG was constructed, and immune responses in mice following oral route delivery of recombinant L. lactis were explored. The production of FaeG expressed in L. lactis was up to approximately 10% of soluble whole-cell proteins, and recombinant FaeG (rFaeG) possessed good immunoreactivity by Western blot analysis. Oral immunization with recombinant L. lactis expressing FaeG induced F4-specific mucosal and systemic immune responses in the mice. In addition, high dose recombinant L. lactis or co-administration of high dose recombinant L. lactis with CTB enhanced the immune responses. These results suggested that L. lactis expressing FaeG was a promising candidate vaccine against ETEC.     

不同干旱胁迫对胡麻种子萌发特性的影响

以胡麻种子为试验材料,渗透剂选用PEG-6000模拟干旱胁迫,探讨了5种干旱胁迫条件(10%、15%、20%、22%、25%m/v)对胡麻种子萌发特性的影响。结果表明,胁迫浓度达到22%时,各品种的发芽势、发芽率、种子萌发指数、种子活力指数均降低,坝亚7号、坝亚12号表现最好,坝亚13号、1062品种表现最差;同一胁迫条件下,不同品种的萌发特性对干旱胁迫的敏感性表现不同,初步分析了不同胡麻品种的抗旱性。     

甘肃临夏州林下经济现状分析与发展思路探讨

介绍了甘肃临夏州发展林下经济的现状,认为发展林下经济意义深远,蕴藏发展潜力;领导重视,凝聚推动力;典型生动,涌现吸引力;难题颇多,必将转化成动力。在此基础上,提出了林下经济的发展目标、发展任务,以及保障措施。     

蔬菜中13种有机磷农药基质效应研究

有机磷农药在农业生产中广泛应用,用气相色谱法进行农药残留检测容易产生基质效应,影响分析结果的可靠性,为研究用气相色谱法进行农残检测过程中有机磷农药在不同蔬菜中的基质效应,选取瓜类、茄果类、叶菜类3类常见蔬菜和13种有机磷农药进行研究,对影响基质效应的因素采取不同变量法进行分析,得出结论:有机磷农药在叶菜类蔬菜中基质效应最大;含有P=O键农药基质效应更强;基质含量越多基质效应越强,并对在检测如何减少基质效应给出了建议.     

兽医机构在食品安全管理中的职能与作用

近年来,"瘦肉精"、"苏丹红"、"三鹿奶粉"等食品安全事件接连发生,食品安全问题成为社会的焦点。食品安全直接关系人民群众身体健康与生命安全,已成为关系国民经济