Studies on the starch and hemicelluloses fractionated by graded ethanol precipitation from bamboo Phyllostachys bambusoides f. shouzhu Yi

Starch from bamboo Phyllostachys bambusoides f. shouzhu Yi evaluated by means of solid-state 13C CP/MAS NMR and X-ray diffraction showed a typical B-type pattern with a very low degree of crystallinity (10.9%). In addition to starch, alkali-soluble hemicelluloses were further fractionated by graded precipitation at ethanol concentrations of 0 (HA), 15, 30, 45, 60, and 75% (v/v). Chemical composition and structural features of the six hemicellulosic subfractions were investigated by a combination of sugar analysis, GPC, FT-IR, GC-MS, 1D (1H and 13C) and 2D (HSQC) NMR spectra, and thermal analysis. The results showed that the bamboo hemicelluloses were O-acetylated 4-O-methyl-glucuronoarabinoxylans (GAX) consisting of a linear (1→4)-β-D-xylopyranosyl backbone decorated with branches at O-3 of α-L-arabinofuranosyl (5-12 mol%) or at O-2 of 4-O-methylglucuronic acid units and acetyl groups (0.8-11 mol%). The molecular weights of these polysaccharides ranged between 13400 and 67500 g/mol, and the molar ratios of A/X and G/X increased with ascending ethanol concentrations. Moreover, xylo-oligosaccharides (XOS) with DP 1-6 were produced by enzymatic hydrolysis of hemicelluloses and the total yields of XOS were range of 21.5 to 40.6%. The structure-property relationships were also established in order to improve enzyme accessibility.     

An arsenate reductase homologue possessing phosphatase activity from sweet potato (Ipomoea batatas [L.] Lam): kinetic studies and characterization

A cDNA encoding a putative arsenate reductase homologue (IbArsR) was cloned from sweet potato (Ib). The deduced protein showed a high level of sequence homology (16-66%) with ArsRs from other organisms. A 3-D homology structure was created based on AtArsR (PDB code 1T3K ) from Arabidopsis thaliana. The putative active site of protein tyrosine phosphatase (HC(X)(5)R) is conserved in all reported ArsRs. IbArsR was overexpressed and purified. The monomeric nature of the enzyme was confirmed by 15% SDS-PAGE and molecular mass determination of the native enzyme via ESI Q-TOF. The IbArsR lacks arsenate reductase activity but possesses phosphatase activity. The Michaelis constant (K(M)) value for p-nitrophenyl phosphate (pNPP) was 11.11 mM. The phosphatase activity was inhibited by 0.5 mM sodium arsenate [As(V)]. The protein's half-life of deactivation at 25 °C was 6.1 min, and its inactivation rate constant K(d) was 1.1 × 10(-1) min(-1). The enzyme was active in a broad pH range from 4.0 to 11.0 with optimum activity at pH 10.0. Phosphatase would remove phosphate group from nucleic acid or dephosphorylation of other enzymes as regulation signaling.     

非定点屠宰生猪的检疫

近来关于非定点屠宰生猪的检疫问题有不同的认识,笔者认为应当依法处理这个问题,此文于2012年12月前完成。     

施加氮肥、硫肥对杞柳提取土壤中铅、镉的影响

以1年生杞柳扦插苗为材料进行盆栽试验,施加氮肥(0、100、200 kg·hm-2·a-1)与硫肥(0、100、200 kg·hm-2·a-1)进行正交试验.生长180 d后,分别测定不同施肥处理对杞柳生物量、重金属吸收量、土壤化学性质的影响.结果表明:同时施加氮肥、硫肥显著促进杞柳生长及对铅(Pb)、镉(Cd)的吸收,其中同时施加N(100 kg·hm-2·a-1)、S(200 kg·hm-2·a-1)处理的生物量、重金属吸收量最高.同时施加氮肥、硫肥显著增加Pb、Cd根部生物富集系数,但是显著降低Pb、Cd枝、叶转运系数.施加氮肥显著降低土壤pH值,同时施加氮肥、硫肥显著降低土壤有机质、速效钾质量分数,显著增加土壤速效磷、硝态氮、有效硫质量分数.主成分分析(PCA)显示,杞柳Pb、Cd吸收总量主要受生物量及根系Pb、Cd质量分数的影响,根系重金属质量分数又受土壤pH、阳离子交换量、铵态氮质量分数的影响.因此,合理施加氮肥、硫肥能促进杞柳生长,改变土壤化学性质,提高重金属生物利用度,提高杞柳对重金属的提取能力.     

基于近红外光谱与BP神经网络预测落叶松木屑的含水率

利用近红外光谱(NIR)技术结合BP神经网络定量预测了落叶松木屑的含水率。首先对采集的落叶松木屑原始近红外光谱进行9点平滑及多元散射校正预处理,然后利用主成分分析法提取光谱数据主成分作为BP神经网络的输入,最后建立BP神经网络预测模型并采用交叉验证法对模型进行验证。所建模型校正集的相关系数R为0.98,校正集的均方根误差RMSEC为0.001 7;预测集的相关系数R为0.99,预测集的均方根误差RMSEP为0.001 5。研究表明,此方法可以实现对落叶松木屑含水率的快速预测。     

Research Progress of Genus Usnea

综述了松萝属地衣植物生物学特性、化学成分和生物活性的研究进展,其化学成分主要为地衣酸和地衣多糖,地衣酸类物质具有很强的抗菌、抗辐射、抗氧化、抗肿瘤和抗病毒等作用,地衣多糖具有提高免疫力、抗氧化、抗肿瘤和抗病毒等作用.     

东北春小麦根腐病防治研究

东北春小麦根腐病Bipolaris sorokiniana(Sacc.ex Sorokin)shoem.是推广抗锈良种后出现的问题。苗期引起根腐,成株期发生叶斑、穗腐和黑胚粒。病菌有两种类型定名为H_1和H_2型,田间前者占优势。病种子和病株残体是田间发病的初侵染源,种子消毒和轮作可减轻苗期根腐并提高种子出苗率。根腐病菌寄主范围很广,来自29种禾本科杂草和作物上的菌株均能侵染小麦。温室和田间试验结果,小麦灌浆乳熟期发病对产量影响最大,也是形成黑胚粒时期。目前尚无免疫品种,农家种和半冬性品种比国外品种和硬粒小麦抗病,Triticum timopheevii表现高抗。采取种植抗病品种结合种子消毒、轮作、增施氮肥等综合防治技术是防治小麦根腐病的有效措施。     

高粱玉米丝黑穗菌交互接种试验

高粱、玉米丝黑穗菌[Sphacelotheca reiliana (Kuhn)Clint.]是否有生理分化现象,两者间能否相互侵染,目前的结论尚不一致。据Al-Sohaily和Mankin,Al-Sohaily、Mankin和Semeniuk,Bressman和Barss、Reed报告,玉米丝黑穗菌不能侵染高梁,而Reed、Swabey和Kolk的结果是两种作物上的丝黑穗菌可以互相侵染。为肯定两者间相互侵染关系,1962—1963年进行了交互接种试验。所用高粱品种1962年为“老母猪跷脚”,1963年为“护2号”,玉米品种为“82号”。丝黑穗菌1962年春分别从高粱、玉米稭上收集的;1963年均是从1962年田间交互接种发病后,为防止污染,于刚抽出黑穗尚未破裂前用厚纸套袋,分别