雪花梨及其亲缘品种S基因型的确定

梨是典型的自交不亲和性果树,自然授粉结实率低,品质差。通过确定梨品种S基因型可寻找简便快速克服自交不亲和性,提高产量,改良品质的方法。根据梨S基因的一级结构特点,利用S基因的保守序列设计特异引物,并对雪花梨及其亲缘品种的基因组DNA进行PCR扩增。将基因组特异扩增电泳只显示一条S基因带雪花梨的特异扩增片段回收并与T载体连接,转化至大肠杆菌中。取其中1个阳性克隆进行测序,并通过生物信息学软件分析确定其核苷酸序列,推导出氨基酸序列,经网上Blast比较,确定该雪花梨S基因片段的S基因型,然后就该S基因进行酶切系统分析,有针对性地挑取另一个阳性克隆测序分析。另外,通过品种间的亲缘关系并经过酶切检测以分析雪花梨亲缘品种的S基因型,并确定各品种的S基因型分别为:雪花S4S16、冀蜜S1S16、雪青S3S16、雪峰S4S16、雪英S3S16、雪芳S4S16。     

丘陵黄壤区不同土层厚度下3个玉米品种花后水分利用效率比较

用水分试验池和人工干旱棚模拟0.4~1.0 m土层夏季干旱胁迫,研究不同基因型玉米花后水分利用特性。结果表明:花后植株伤流强度、叶片RW C、保水力与品种的抗旱性正相关,品种的抗旱性由强至弱的顺序为C 19>C 202>C 14,并且干旱处理的伤流强度和叶片RW C随土层增厚而增强;夏旱导致玉米灌浆持续期缩短2~4d,抽雄吐丝间隔期延长0~7 d;土层厚度和品种抗旱性均与籽粒产量和WUE正相关,土层深厚(1 m)夏旱胁迫处理有利于抗旱品种成单19提高籽粒产量和WUE。但以0.7 m土层的平均产量和WUE最高,其可作为坡耕地改造和利用的参考指标之一。     

犬细小病毒南京分离株基因型分析

采用PCR技术对不同来源的犬细小病毒毒株进行了基因型鉴定,发现所鉴定的1982~2004年的5株犬细小病毒南京分离株和荷兰Intervet疫苗株(CPV-V154)均为CPV-2b亚型,而且相互之间的同源性均高于98.4%。     

Variation in virus populations and growth characteristics of two sugarcane cultivars naturally infected by Sugarcane yellow leaf virus in different geographical locations

Two sugarcane cultivars (R570 and SP71-6163) naturally infected by Sugarcane yellow leaf virus (SCYLV) were each imported from several geographical locations into a sugarcane yellow leaf-free environment (Montpellier, France). Plants were grown as plant cane for 5–6 months and the experiment was repeated for three consecutive years (2003–2005) in a greenhouse. Several sugarcane-growth and disease characteristics were monitored to identify variation in pathogenicity of SCYLV. Depending on their geographical origin, sugarcane cvs R570 and SP71-6163 were infected by SCYLV genotypes BRA-PER or REU, or a mixture of the two. Severity of symptoms did not vary between plants of cv. R570, but variation in disease severity between plants of cv. SP71-6163 from different geographical locations suggested the occurrence of pathogenic variants of SCYLV. For each sugarcane cultivar, differences in stalk length, number of stalk internodes, virus titre in the top visible dewlap leaf, and percentage of infection of leaf and stalk phloem vessels were also found between plants from different geographical origins. However, these differences were not always reproducible from one year to another, suggesting occurrence of different plant responses to SCYLV isolates under varying environmental conditions.     

不同基因型新城疫病毒强毒株对鸡的致病性

就不同基因型新城疫病毒强毒株对鸡的致病性进行了比较。用3种基因型（Ⅵg、Ⅶd亚型、Ⅸ型）新城疫病毒强毒株分别人工感染25日龄雏鸡，结果各株病毒接种鸡均100％发病、100％死亡，表现出嗜内脏型新城疫病毒感染引起的典型的新城疫症状和病理变化。免疫组化检测发现．攻毒鸡多种组织器官中能检测到病毒抗原，在能检测到病毒抗原的器官中，病毒抗原主要定位于淋巴细胞、网状细胞、巨噬细胞、肝细胞及各种上皮细胞的胞浆内；新城疫病毒对肠相关淋巴组织的亲嗜性优先于附近的上皮。本试验结果表明．基因Ⅵg、Ⅶd亚型、Ⅸ型新城疫病毒强毒株对鸡均具有高度致病性。     

TT基因型龙桑选育的研究

本试验是在1989年试验的基础上进行的,为了得到具有纯合的控制龙桑曲枝性基因(TT)的植株,对1989年获得的T型苗以天然授粉的方法进行测交,在已开花的39株中,发现有4株的基因型为TT.今后,由这些具有TT基因型的植株上所获得的种子育苗时,所获得的全部幼苗都将表现出曲枝性的特征.因而简化了龙桑苗木的繁殖方法,并可以比较容易地大批量的获得龙桑苗木.     

Antigenic Characterization of Rabies Virus Isolates from Vaccinated Dogs in Plateau State,Nigeria

Rabies isolates (genotype 1 lyssaviruses) from vaccinated dogs that died of rabies infection in the Plateau area of Nigeria were characterized using monoclonal antibodies (MAbs). The isolates were examined for rabies (genotype 1) and rabies-related (genotypes 2, 3 and 4) viruses by the indirect fluorescent antibody test carried out with MAb 502-2, which recognizes the nucleocapsid protein of all known lyssaviruses, and with MAb 422-5, which identifies only rabies-related viruses. All three isolates showed positive immunofluorescence with MAb 502-2 and were negative with MAb 422-5, indicating that they were all rabies (genotype 1) viruses.Characterization with a panel of 36 anti-nucleocapsid monoclonal antibodies showed that all three isolates reacted positively with 35 of the anti-nucleocapsid MAbs, including MAb 102-27 and MAb 377-7. Characterization using a panel of 44 anti-glycoprotein MAbs differentiated the isolates sharply from LEP Flury and PM vaccine viruses. The pattern of anti-glycoprotein reactivity of the isolates showed them to belong to one distinct viral subtype, except for a minor variation in one isolate that was not neutralized by MAb 1101-3. None of the three isolates was identified as the Flury low egg passage (LEP) vaccine strain used for vaccinating dogs in Nigeria. In fact, all the three isolates had the typical pattern of reactivity of isolates from unvaccinated dogs, including MASS 83, a rabies virus isolated in Nigeria and characterized at the Wister Institute before this study.     

Reaction of six Musa genotypes to root-parasitic nematodes

The reaction of six Musa genotypes to root-parasitic nematodes was evaluated under field conditions, together with the horizontal, and vertical distributions of the neomatodes within the soil profile. The numbers of Radopholus similis, Helicotylenchus spp., Meloidogyne spp. and of all nematodes in the excavated soil quadrant varied with Musa genotype. All genotypes were very susceptible to at least one nematode. Yangambi km5, Pisang Jari Buaya and FHIA-23 supported the lowest number of R. similis and Pisang Jari Buaya, the lowest number of Helicotylenchus spp. These three cultivars supported high numbers of Meloidogyne spp. Furthermore, FHIA-23 supported high numbers of Helicotylenchus spp. The horizontal and vertical distributions of R. similis in the root system of Valery, Gros Michel and FHIA-18 were very similar. By constrast, the distributions of Helicotylenchus spp., Meloidogyne spp. and the number of all nematodes varied slightly among the genotypes. Because Musa genotypes susceptible to a particular nematode showed a similar horizontal and vertical nematode distribution with populations concentrated in the vicinity of the plant base (0–30 cm horizontal distance and 30 cm depth), sampling at this site would be sufficient for the identification of the Musa plant reaction.     

X染色体60149273位点在脂尾（臀）和瘦尾绵羊品种中的多态性及其基因定位

【目的】研究绵羊X染色体60149273位点在不同沉脂尾型绵羊品种中的多态性,为解析绵羊尾脂沉积性状的遗传机制提供基础数据。【方法】首先,采用PCR-SSCP分型方法检测X染色体60149273位点在不同脂尾类型绵羊品种的多态性,并借助PCR产物直接测序的方法确认各基因型相应序列,利用卡方检验的方法检测各基因型分布在不同品种中的平衡性。其次,利用生物信息方法将该SNP定位与绵羊androgen receptor（AR）,并使用电子克隆的方法克隆出绵羊AR全长编码序列。同时以阿勒泰羊臀部脂肪RNA为材料,采用RT-PCR的方克隆绵羊AR第3—8外显子序列,利用生物信息学方法分析序列同源性以及序列的物种进化保守性。【结果】①PCR-SSCP结果显示,在脂尾（臀）型绵羊品种阿勒泰羊和湖羊群体中X染色体60149273位点未检出多态性,GG基因型占100%;而瘦尾（臀）型绵羊品种中国美利奴和萨福克羊群体中则出现了多态性,GG基因型分别下降至10%和21%。②利用比较基因组学首次电子克隆出该SNP所属基因AR的全长编码区,并从阿勒泰羊臀脂mRNA中成功扩增羊源AR第3—8外显子片段,测序结果与电子克隆序列完全一致。③物种同源性比对进一步显示,AR在哺乳类动物中高度保守,哺乳动物各物种间同源性高达90%;进化树分析结果显示,牛、绵羊、海豚和猪等哺乳动物亲缘较近。【结论】首次发现绵羊AR第3内含子一处SNP在脂尾（臀）与瘦尾绵羊品种中存在较大差异,该SNP将可作为一个分子标记运用于低脂绵羊新品种的培育,同时该SNP所属AR也可作为一个重要候选功能基因应用于绵羊尾（臀）脂沉积分子机制的相关研究。     

Response of western hemlock crosses to nitrogen and phosphorus supply

Seedlings of nine controlled crosses of westernhemlock (Tsuga heterophylla (Raf.) Sarg.) withknown differences in growth rate after six years inthe field were grown for one year, and then subject tothree nutrient treatments. Nutrient treatments variedthe amount of nitrogen (N) and phosphorus (P) innutrient solutions as follows (N:P): 20:4 mgL^–1,100:20 mgL^–1, and 250:60 mgL^–1. Nutrientsolutions were used to subirrigate pots containing theseedlings in a peat:perlite medium for two growingseasons. Biomass and foliar N and P concentrationsincreased while nutrient productivity (biomass/shootN content) decreased with increasing nutrient supply. The nine crosses were divided into fast, medium andslow-growing parental ranks. There was a significantparental rank × nutrient treatment interaction forshoot and total biomass, and root:shoot ratio. Theresults indicate that tree improvement programs forwestern hemlock should plant progeny trials on sitesof different fertilities to examine relative responseof crosses.