Genetic analysis of ORF5 of recent Korean porcine reproductive and respiratory syndrome viruses (PRRSVs) in viremic sera collected from MLV-vaccinating or non-vaccinating farms

The 23 open reading frame (ORF) 5 sequences of Korean type II porcine reproductive and respiratory syndrome virus (PRRSV) were collected from viremic sera from the (modified live vaccine) MLV-vaccinating and non-vaccinating farms from 2007 to 2008. The samples were phylogenetically analyzed with previous ORF5 sequences, including type I Korean PRRSV, and previously reported or collected sequences from 1997 to 2008. A MN184-like subgroup of type II Korean PRRSV was newly identified in the viremic sera collected from 2007 to 2008. And of the type I PRRSVs, one subgroup had 87.2~88.9% similarity with the Lelystad virus, showing a close relationship with the 27~2003 strain of Spain. The maximum parsimony tree of type II PRRSV from 1997 to 2008 showed that they had evolved to four lineages, subgroups 1, 2, 3 and 4. Most of the recently collected type II PRRSVs belonged to subgroup 4 (48%). The region of three B-cell epitopes and two T-cell epitopes of ORF5 amino acids sequences was considerably different from the MLV in subgroups 3 and 4. In conclusion, the existence of type I PRRSV, which was genetically different from Lelystad virus (Prototype of type I PRRSV), and heterologous type II PRRSVs of viremic pigs detected even in the MLV-vaccinating farms indicated the need for new vaccine approaches for the control of PRRSV in Korea.     

滇东南岩溶山区4个树种的造林试验结果分析

通过在砚山县铳卡农场对圣诞树、滇合欢、新银合欢、刺槐4个树种不同造林密度、施肥措施、苗根处理方式及苗期喷云大-120等5个因素的对比试验,幼树期的结果表明树种对林木生长量及生物量的影响最大,施肥措施和苗根处理方式对林木的生长发育也具有一定的作用,而苗期喷云大-120对定植后林木的生长发育作用不明显,密度效应除圣诞树外其他3个树种还不显著。参试的4个树种中,圣诞树3年生时已经郁闭,其最佳技术组合A1B1C1D1E1的树高、地径、冠幅和单株生物量分别为5.05m、4.72cm、1.79m和7.05kg,每公顷可提供薪材22678kg、绿肥和饲料24345.5kg,产值3485.08元;滇合欢的最佳技术组合A2B1C2D2E1的树高、地径、冠幅和单株生物量分别为1.84m、4.33cm、1.23m和1.26kg,每公顷可产薪材6936.8kg、绿肥和饲料1467.4kg,产值767.05元;新银合欢则不太适应试区的气候,每年都受霜冻的危害。预计在滇东南岩溶山区选择多用途的圣诞树和滇合欢,采用最佳的技术措施组合造林,能取得良好的生态效益和经济效益。     

南沙群岛重点岛礁潟湖微型浮游动物的群落结构与摄食

潟湖是岛礁生物多样性演变的重要环境场,在岛礁水生态系统的物质循环和能量流动中发挥重要作用,而微型浮游动物的生态功能研究是解析南沙群岛岛礁水域潟湖生态系统初级生产力组成、流向、能量流动效率的重要研究内容之一。实验通过对南沙群岛重点岛礁渚碧礁、美济礁与永暑礁潟湖表层水域中微型浮游动物与生态环境调查,研究了其群落结构及其与环境因子的关系,并通过稀释培养实验研究了微型浮游动物的摄食压力。结果显示,调查水域共发现微型浮游动物20种,总丰度的范围为320～1 460个/L,以无壳纤毛虫丰度最高。无壳纤毛虫在渚碧礁潟湖西部水域（ZB-1）丰度最高,砂壳纤毛虫峰值则出现在永暑礁潟湖中部水域（YS-3）,桡足类幼体丰度最大值出现在美济礁潟湖北部水域（MJ-2）。聚类分析结果显示,3个岛礁潟湖中部区域的微型浮游动物群落相似度较高,溶解氧是影响群落结构的最重要因素,特别是对MJ-3站位影响最为突出。摄食实验结果显示,3个岛礁潟湖水域浮游植物生长率为0.22～1.36 d^-1;微型浮游动物摄食率范围为0.22～0.60 d^-1,微型浮游动物每天约摄食浮游植物现存量的...     

QTL mapping for capsaicin and dihydrocapsaicin content in a population of Capsicum annuum ‘NB1’ × Capsicum chinense ‘Bhut Jolokia’

Capsaicinoids are pungent compounds used for industrial and medical purposes including food, medicine and cosmetics. The Indian local variety ‘Bhut Jolokia’ (Capsicum chinense Jacq.) is one of the world's hottest chilli peppers. It produces more than one million Scoville heat units (SHUs) in total capsaicinoids. In this study, our goal was to identify quantitative trait loci (QTLs) responsible for the high content of capsaicin and dihydrocapsaicin in ‘Bhut Jolokia’. Capsicum annuum ‘NB1’, a Korean pepper inbred line containing 14 000 SHUs, was used as a maternal line. An F₂ population derived by crossing between ‘NB1’ and ‘Bhut Jolokia’ was generated to map QTLs for capsaicinoids content. A total of 234 markers, including 201 HRM, 21 SSR, 2 CAPS and 10 gene‐based markers of the capsaicinoid synthesis pathway, were mapped. The final map covered a total distance of 1175.2 cM and contained 12 linkage groups corresponding to the basic chromosome number of chilli pepper. Capsaicin and dihydrocapsaicin content were analysed in 175 F₂ pepper fruits using the HPLC method. The maximum total capsaicinoids content was 1389 mg per 100g DW (dry weight), and the minimum content was 11 mg per 100g DW. Two QTLs (qcap3.1 and qcap6.1) for capsaicin content were identified on LG3 and LG6, and two QTLs (qhdc2.1 and qdhc2.2) for dihydrocapsaicin content were located on LG2. We did not detect QTLs for total capsaicinoids content. The QTL positions for capsaicin content were different from those for dihydrocapsaicin content. These results indicate that the complexity of selecting for more pungent chilli peppers must be considered in a chilli pepper breeding programme. The QTL‐linked markers identified here will be helpful to develop more pungent pepper varieties from ‘Bhut Jolokia’, a very hot pepper.     

甘蓝染色体及伸长DNA纤维制备技术的研究

以甘蓝根尖、花药、黄化苗等为材料,初步建立了甘蓝有丝分裂前中期染色体、减数分裂粗线期染色体以及伸长DNA纤维等3种具有不同空间分辨率的靶DNA载体的制备技术.结果表明:通过变温处理可以有效提高前中期染色体分裂相比率;采用0.002 mol/L 8-羟基喹啉20℃预处理1 h、2%纤维素酶和2%果胶酶混合液37℃酶解约2 h、0.075 mol/L氯化钾25℃低渗30 min,制备的前中期染色体效果最佳;2%纤维素酶和2%果胶酶混合液37℃酶解约3 h,可获得伸展良好、背景干净的粗线期染色体;分子梳理法与移动界面法相比,前者制备的伸长DNA纤维效果较好.此方法的建立为荧光原位杂交技术在甘蓝相关研究领域的应用打下了坚实的基础.

Abstract：

A method of preparation was established for different FISH (fluorescence in situ hybridization)resolution on prometaphase and pachytene chromosomes and extended DNA fibers with roots, anthers and albino seedlings of Brassica oleracea. Alternating temperature treatment effectively improved the divisionindex of prometaphase cells. Optimum results were obtained for the preparation of prometaphase chromosomes when pretreatment was made with 0. 002 mol/L 8-hydroxy quinoline at 20 ℃ for 1 h before treatment with the enzyme mixture of 2% cellulase and 2% pectase at 37 ℃ for approximately 2 h in combination with a hypotonic treatment with 0. 075 mol/L potassium chloride at 25 ℃ for 30 min. Well-spread pachytene chromosomes with clear background were obtained through the treatment with the enzyme mixture of 2% cellulase and 2% pectase at 37 ℃ for about 3 h. Molecular combing was better than moving interface for preparing extended DNA fibers. The method lays a solid foundation for the application of FISH in B. oleracea.     

低温弱光下辣椒幼苗叶绿素荧光特性及其与品种耐性的关系

选取4份耐低温弱光性不同的辣椒品种,以耐低温弱光指数作为品种耐性鉴定的依据,研究了四叶一心期,昼/夜温度10 ℃/5 ℃,光照70 μmol ? m-2 ? s-1的低温弱光下叶片叶绿素荧光特性,分析了其与耐低温弱光指数的关系。结果表明,低温弱光处理后,辣椒叶片的初始荧光（Fo）、最大荧光（Fm）、光合系统Ⅱ（PSⅡ）最大光化学量子产量（Fv/Fm）和光化学淬灭系数（qP）呈降低趋势;非光化学淬灭系数（qN）在处理3和5 d显著上升,处理7 d,非耐性品种qN显著下降,耐性品种qN显著上升或无显著变化;最大相对电子传递速率（rETRmax）和快速光响应曲线初始斜率（α）呈下降趋势;半饱和光强（Ik）在非耐性品种中呈下降趋势,但在耐性品种中呈上升趋势;随着光照强度不断增强,qP不断下降,但耐性品种发生完全光抑制的光强显著大于非耐性品种。Fo、Fm、qP、qN、Fv/Fm、rETRmax、α、Ik等叶绿素荧光参数与耐低温弱光指数显著相关,其中rETRmax最稳定灵敏。qP光响应曲线和rETRmax可作为实际生产中辣椒耐低温弱光的主要筛选指标。     

无公害芋艿产业化发展的障碍因素及对策

芋艿是金华市发展效益农业的主要农产品之一,在解决金华市“三农问题“中起到推动作用.文章在分析金华芋艿产业化发展中存在障碍因素的基础上,提出了推进无公害芋艿生产标准化的实施和产业化生产的发展对策.     

山羊胚胎脊髓灰质的发育

对山羊胚胎脊髓灰质形成和发育的形态学变化进行了系统研究。结果表明 :山羊脊髓神经管闭合以后 ,其组织发生持续近 2 0 d才形成完整的 3层同心圆结构 ;山羊脊髓神经管的组织发生和脊髓灰质的形成在时间上有很大程度的重叠性 ;脊髓灰质各结构形成和发育的规律也不完全一致 ,有些结构发生早 ,而神经元分化较晚 ,如侧角、胶状质 ;有些结构发生虽然晚 ,但其中的神经元胞体分化和发育则较早 ,如 Clarke氏背核 ;有些结构发生早 ,神经元发育也早 ,如腹角运动神经元。     

我国开征房产税的可行性研究

随着房价的居高不下,房产税的征收在近期已成为热门话题。通过研究房产税开征的情况,追溯房产税的历史起源,考察征收房产税的原因,以及分析在现时的中国征收房产税的特殊情况,并综合运用比较法、例证法等各种方法,以期在众说纷纭中,得到一个清醒的认识,并最终说明房产税征收的时机并不成熟,现在的征收热还只是国家的造势之举     

苗木切根技术研究进展

精准培育的理念已经渗入到森林培育的各个环节。切根作为干扰根系最为重要的技术,也受到越来越多地重视。切根可以划分为芽苗切根、苗期切根和起苗后切根等3种类型,把平截、扭根、侧方修根、盒式修根等称为苗期切根,是狭义切根范畴。结合苗木形态指标、生理指标和造林效果,综述每一类型的切根对苗木质量和造林效果的影响。以辐射松为代表的主根发达树种,通过芽苗切根、苗期的平截和扭根,抑制根系顶端优势,从而降低苗木高生长,促进侧根发育,形成发达、紧凑的根系,调整苗木地上和地下比例,最终提高苗木造林效果。以花旗松为代表的慢生常绿树种,侧根较为发达,切根效果不一。苗木平截和扭根后,内源激素、矿质营养、碳水化合物、水分等均会发生变化,这种变化如何影响苗木质量的机制尚不明确。