基于全溶体系的毛竹竹材木质素分离方法

  目的  以毛竹Phyllostachys edulis竹材为原料，经球磨分别通过LiCl/DMSO溶剂体系的溶解、再生处理、纤维素酶水解，得到的酶解残渣进行溶剂抽提、纯化，分离出竹材中的再生酶解木质素（RCEL）。  方法  木质素化学成分按照标准方法测定，木质素结构单元的变化通过红外、碱性硝基苯氧化、核磁共振波普分析，采用X射线衍射比较再生前后的纤维素结晶区变化。用凝胶渗透色谱测定木质素的分子量及其分布。  结果  经由化学成分结果得知:RCEL的得率和纯度都较高。经红外、元素分析、硝基苯氧化、凝胶渗透色谱、核磁共振等手段表征表明:分离得到的竹材RCEL为GSH型木质素，缩合程度略高于纤维素酶解木质素（CEL），其中，紫丁香基结构单元含量较高，达50%，分离过程中结构单元比例没有变化。从分子量及其分布来看，竹材RCEL数均分子量和重均分子量都较高，分离过程中木质素降解较少。经X射线衍射分析，经LiCl/DMSO体系溶胀处理后纤维素的结晶度有所下降。RCEL木质素热失重温度为200~600℃，600℃后失重趋于稳定，木质素缩合程度不同会导致不同的热解特性。  结论  基于LiCl/DMSO溶剂体系的分离方法，对木质素大分子结构有较好的保护作用，对碳水化合物有很好的降解作用，可以改变纤维素结晶区的结构，降低结晶度，从而能促进纤维素的降解，提高酶解效率，有利于高效分离CEL。与传统分离方法得到的球磨木质素（MWL）、CEL相比，经过LiCl/DMSO溶剂体系处理后得到的竹材RCEL，能较好地代表竹材的木质素。     

马铃薯连续机械式去皮机优化与试验

分析了现有马铃薯去皮机的结构特点，对机械去皮机的滚筒毛刷结构做了优化设计。经单因素和响应面试验分析，得到马铃薯去皮机的最优工艺参数:滚筒转速18 r/min，滚筒高度差15 mm，喂入量39 kg/min，此条件下马铃薯的去皮率为80.93%，去皮效果较好。试验结果可为实际马铃薯采后去皮加工提供重要理论参考依据。      

两种紫葳科藤本植物扦插育苗技术研究

硬骨凌霄、紫云藤为紫葳科藤本中应用范围广、市场需求量较大的两个品种,为探索它们的扦插育苗技术,采用正交设计的试验方法对两种植物插穗规格、留叶方式、留芽数量的选取进行研究,并对正交试验的结果进行了验证,探讨了不同生根剂处理下两种植物的扦插生根情况.研究结果表明,插穗直径、插穗长度、留叶方式和留芽数量这4个因素对硬骨凌霄和紫云藤的扦插成活率有着极显著的影响.对于硬骨凌霄来说,插穗直径对其扦插成活率的影响最大,留芽数量次之,再次为留叶方式和插穗长度;对紫云藤,留芽方式是影响其扦插成活率的最关键因素,其次是插穗的直径、长度和留叶方式.生根剂的使用可以极显著提高紫葳科藤本植物的扦插成活率,选择直径0.80 cm的硬骨凌霄当年生藤条制成长8 cm、保留2个半片叶和2个芽的穗条,并用浓度为500 mg·L-1的NAA溶液处理2 h后进行扦插,扦插成活率可达83.33％;选择直径1.0 cm的紫云藤当年生藤条制成长10 cm、保留1个半片叶和2个芽的穗条,并用浓度为500 mg·L-1的NAA溶液处理2 h后进行扦插,扦插成活率也可达83.33％.本研究得出的制穗方案和生根剂的选择方案可适用于硬骨凌霄和紫云藤这两种紫葳科藤本的扦插育苗,也可为其它植物扦插育苗提供参考.     

Production,Characterization and Immunomodulatory Activity of an Extracellular Polysaccharide from Rhodotorula mucilaginosa YL-1 Isolated from Sea Salt Field

A novel exopolysaccharide from marine-derived red yeast Rhodotorula mucilaginosa strain YL-1 was produced and characterized. The highest yield of polysaccharide reached 15.1 g/L after medium and culture parameter optimization. This exopolysaccharide, composed of four neural monosaccharides including glucose, mannose, galactose and fucose, had an average molecular weight of 1200 KDa. It had good immunomodulatory activity on RAW256.7 cell lines. ELISA (enzyme linked immunosorbent assay) and Q-PCR (quantitative real-time PCR) results showed that the cell was stimulated to express more IL-6, IL-18, IL-1β and TNFα cytokines than the control group. This is the first report of an exopolysaccharide with immunomodulatory activity from marine-derived Rhodotorula mucilaginosa.     

2013年国外家兔遗传育种研究进展

我国是养兔大国，但家兔遗传育种基础研究薄弱。文章对2013年国外家兔遗传育种最新研究进展进行综述，以期为国内家兔育种者提供参考。     

Time‐lapse monitoring of soil water content using electromagnetic conductivity imaging

The volumetric soil water content (θ) is fundamental to agriculture because its spatiotemporal variation in soil affects the growth of plants. Unfortunately, the universally accepted thermogravimetric method for estimating volumetric soil water content is very labour intensive and time‐consuming for use in field‐scale monitoring. Electromagnetic (EM) induction instruments have proven to be useful in mapping the spatiotemporal variation of θ. However, depth‐specific variation in θ, which is important for irrigation management, has been little explored. The objective of this study was to develop a relationship between θ and estimates of true electrical conductivity (σ) and to use this relationship to develop time‐lapse images of soil θ beneath a centre‐pivot irrigated alfalfa (Medicago sativa L.) crop in San Jacinto, California, USA. We first measured the bulk apparent electrical conductivity (EC_a – mS/m) using a DUALEM‐421 over a period of 12 days after an irrigation event (i.e. days 1, 2, 3, 4, 6, 8 and 12). We used EM4Soil to generate EM conductivity images (EMCIs). We used a physical model to estimate θ from σ, accounting for soil tortuosity and pore water salinity, with a cross‐validation RMSE of 0.04 cm³/cm³. Testing the scenario where no soil information is available, we used a three‐parameter exponential model to relate θ to σ and then to map θ along the transect on different days. The results allowed us to monitor the spatiotemporal variations of θ across the surveyed area, over the 12‐day period. In this regard, we were able to map the soil close to field capacity (0.27 cm³/cm³) and approaching permanent wilting point (0.03 cm³/cm³). The time‐lapse θ monitoring approach, developed using EMCI, has implications for soil and water use and management and will potentially allow farmers and consultants to identify inefficiencies in water application rates and use. It can also be used as a research tool to potentially assist precision irrigation practices and to test the efficacy of different methods of irrigation in terms of water delivery and efficiency in water use in near real time.     

草果AtNCED基因克隆、表达和植物表达载体构建

9-顺式环氧类胡萝卜素双加氧酶(9-cis-epoxycarotenoid dioxygenase, NCED)是ABA生物合成的限速酶。诸多研究表明NCED基因表达量的变化与ABA含量显著相关,在种子休眠过程中发挥重要作用。为探究草果AtNCED基因的序列特征和功能,本研究以草果(Amomum tsaoko Crevost et Lemarie)种子转录组为基础,采用RT-PCR技术克隆了一个AtNCED基因。该基因全长2 372 bp,包含一个1 830 bp的开放阅读框(open reading frame, ORF),编码610个氨基酸。生物信息学分析显示,AtNCED基因编码的蛋白在N-末端包含典型的叶绿体转运肽序列,在催化结构域含有4个高度保守的组氨酸残基。AtNCED蛋白与芭蕉科马来西亚蕉同源性较高,与其他单子叶植物处在同一进化分支。实时荧光定量PCR分析结果表明,AtNCED基因表达量随着层积时间的增加逐渐下降,该基因可能正向调控种子休眠,在草果种子休眠诱导与维持中发挥重要作用。进一步地,利用同源重组方法,成功构建了pBI121-AtNCED过表达载体,并转化至农杆菌EHA105。该研究结果为弄清ABA激素信号在种子休眠中的调控作用提供了帮助。     

Atmospheric humidity and genotype are key determinants of the diurnal stomatal conductance pattern

Great understanding of the genotypic difference in diurnal stomatal conductance (g_s) pattern and the key determinants of the pattern is important for saving water by adopting cultivars appropriately. Fifteen wheat genotypes were studied under different soil conditions and various meteorological conditions with pot cultivation in rain shelter for two years. Genotype and air humidity were found to be key determinants of diurnal g_s pattern. All genotypes under low relative humidity (LRH) and most genotypes under high relative humidity (HRH) displayed a gradual decline pattern from morning through the afternoon. Under moderate relative humidity (MRH), all genotypes present a single-peak curve pattern, but they differed in peak time, which may lead to unreliable g_s comparison between genotypes and get ostensible contrasting materials. The stomatal conductance was significantly different among genotypes under LRH and the increased g_s magnitude is also significantly different when it was compared between LRH and HRH. The present results provide new thinking for selecting and adopting appropriate cultivars with specific stomata traits for the area with various meteorological conditions.     

黄河流域机采棉植株性状的筛选

为筛选适合黄河流域棉区机采的品种,对16份棉花材料的果枝始节高度、株高、产量构成因素、纤维品质指标进行系统调查、分析与研究。结果表明:适合进一步培育机采品种的材料为590032、中棉所49。