囊萼紫草属与滇紫草属花粉形态比较研究

本文借助光学显微镜和扫描电镜研究了囊萼紫草属3种和滇紫草属12种植物的花粉形态。囊萼紫草属的花粉为哑铃形或茧形,中等大小,P／E比为1．6一1．67,三孔沟,内孔横长;具小刺状纹饰。滇紫草属的花粉为近长球形或近卵球形,P／E为l—1．23;三孔沟或三合沟孔,内孔一般纵长,具皱波状纹饰,在皱波上具密集的小瘤或微颗粒。从花粉形态的角度,本文支持把囊萼紫草属从滇紫草属(广义)中分离出来的观点。值得注意的是,在滇紫草属的花粉中首次观察到了一种比较少见且特化的花粉即单极三合沟孔的花粉。     

The interaction of RepC initiator with iterons in the replication of the broad host-range plasmid RSF1010.

The replication origin of the broad host-range plasmid RSF1010 contains 3.5 copies of a 20mer iteron sequence that bind specifically to the plasmid-encoded initiator, RepC. Here we demonstrated that even a single iteron was bent upon binding of RepC. Moreover, the bending angle seems to become larger along with the increment of the number of iterons. In a mutational analysis of the iteron sequence, we isolated seven kinds of base-substitution mutants of iterons, and estimated the replication activity of these mutants in vivo. We found that each of the subsections in the 20mer iteron sequence made a distinct contribution to the initiation of RSF1010 DNA replication. With the binding assay of RepC and mutated iterons in vitro, we found that the formation of a productive RepC-iteron complex was required for the initiation of plasmid DNA replication.     

Human DNA helicase IV is nucleolin, an RNA helicase modulated by phosphorylation

The cDNA encoding human DNA helicase IV (HDH IV), a 100-kDa protein which unwinds DNA in the 5′ to 3′ direction with respect to the bound strand, was cloned and sequenced. It was found to be identical to the human cDNA encoding nucleolin, a ubiquitous eukaryotic protein essential for pre-ribosome assembly. HDH IV/nucleolin can unwind RNA-RNA duplexes, as well as DNA-DNA and DNA-RNA duplexes. Phosphorylation of HDH IV/nucleolin by cdc2 kinase and casein kinase II enhanced its unwinding activity in an additive way. The Gly-rich C-terminal domain possesses a limited ATP-dependent duplex-unwinding activity which contributes to the helicase activity of HDH IV/nucleolin.     

Targeted disruption of the TGA3 locus in Arabidopsis thaliana

A major drawback to study gene functions in plant systems is the lack of an effective gene knockout strategy. With a large number of plant genes isolated and the accelerating pace by which this collection is growing, the need for their functional analyses at the whole plant level has become increasingly urgent. Here evidence is reported for the first successful disruption of a non-selectable gene in Arabidopsis thaliana by creating a mutant of the TGA3 locus via targeted insertion of the bacterial neo gene conferring kanamycin (Km) resistance. A β-glucuronidase (GUS) expression unit outside the region of homology was used as a screenable marker to distinguish homologous recombination events from those of ectopic insertions. PCR amplification coupled with Southern blot screening identified two putative homologous recombination events among 2580 Km^r calli. One callus line was subsequently isolated and the structure of the targeted TGA3 allele confirmed by Southern blot analyses. This study demonstrates the feasibility of targeting a non-selectable locus in Arabidopsis. Combined with future improvements in negative selection strategies and efficient, transformation methodologies, gene replacement studies in plants could become a routine technique.     

猕猴桃种质资源保存及育种研究

收集保存猕猴桃属植物３５种或变种、变型,并将它们分为抗寒?喜凉、喜温３种类型。从保存的中华猕猴桃优株中系统选育出“武植２号”、“武植３号”２个优良品种。以中华猕猴桃为母本,毛花猕猴桃为父本进行种间杂交,从杂种Ｆ１代中培养出“江山娇”、“满天星”、“重瓣”３个具有园艺观赏价值的优良株系。这些研究工作为猕猴桃种质资源的保存及新品种的培育奠定了工作基础。     

兰属(Cymbidium)5种植物叶结构特征

采用光学显微镜和体视镜,对兰属5种植物（春兰、蕙兰、建兰、寒兰、墨兰）的叶结构特征（叶脉结构、叶表皮结构、解剖结构）进行了观察和测量。结果显示,兰属5种植物的叶脉结构相似,叶表皮结构和解剖结构存在较大差异,其中最主要的差异是皮下纤维束的多少和边缘角质层锯齿形态。依据叶结构特征聚类分析结果,5种兰可分为春兰组、建兰组和墨兰组3组。本研究表明叶结构特征对兰属5种植物的分类具有重要意义。     

小麦根系特征对干旱胁迫的响应

干旱胁迫时, 小麦(Triticum aestivum)根系率先产生应激响应, 同时向地上部发出信号, 诱导地上部发生生理反应, 从而提高植株抗旱能力。根系构型包括平面几何性状和立体几何结构(即拓扑构型), 具有遗传稳定性和可塑性。干旱胁迫影响根系理化特性, 如根源化学信号、根系细胞酶类和根系渗透作用的响应。根系通过调整其解剖学结构和水分吸收动力等来适应干旱胁迫。该文从根系构型、理化特性和解剖学结构3个方面, 系统阐述了小麦根系特征对干旱胁迫的响应, 并探讨了其与干旱胁迫的关系和当前研究中存在的问题, 以期为相关研究提供参考。     

木姜子叶精油的化学成分研究

采用气相色谱-质谱联用仪对产于秦岭太白山的木姜子叶的挥发油成分进行分析鉴定,从分离出的79个峰中鉴定了32种成分,其含量占挥发油总量的90.59％,主要成分为1,3,3-三甲基-乙-氧杂双环[2,2,2]辛烷(59.96％),1,8-桉油醇(8.96％),香茅醛(6.86％),2-甲基-5-(1-甲基乙烯基)环己酮(4.34％)和澄花醇乙酯(3.19％)。     

荧光显微镜观察大蒜油对腹水癌细胞的影响

用吖啶橙染色,荧光显微镜观察大蒜油对—S180,昆明小鼠,U14 C57BL/6J小鼠和L1210DBA小鼠的癌细胞作用的影响,结果表明大蒜油有直接破坏癌细胞的DNA,RNA和分裂中期染色体的作用。给药后2—6小时作用最强,12小时后癌细胞数逐渐恢复,因此给药间隔不应超过12小时。我们研究证实大蒜油有明显的抗癌作用,为临床应用提供有力的依据。     

Expression of a gene encoding a rabbit sperm membrane protein in mammalian cells.

A general mammalian expression vector designated pSV2-EP was reconstructed by inserting an oligonucleotide fragment into pSV2-dhfr. This vector allowed insertion of cDNAs with EcoRI cohesive ends. The pSV2-EP contains a simian virus 40 (SV40) early promoter, origin for DNA replication, SV40 poly-A site, splicing site, an initiator ATG downstream from the promoter and an EcoRI site for the insertion of cDNA fragment screened from lambda gt11 expression libraries. A recombinant plasmid (pS-VRS-1) was constructed by inserting RSD-1, a cDNA encoding a rabbit sperm tail protein, into the EcoRI site of the pSV2-EP vector. Chinese hamster ovarian (CHO) dhfr-negative cells were cotransformed with pSV2-dhfr and pSVRS-1 by the calcium phosphate method. In selective culture medium without thymidine and hypoxanthine, several cell lines were obtained containing mRNA and DNA that hybridized with RSD-1. One of these transformed cell lines stained intensely with anti-rSMP-B antibodies, demonstrating that the RSD-1 was expressed in the transformed CHO cells.