‘嘎拉’苹果果实品质的电学特性研究

以'嘎拉'苹果果实为材料,在0.1～100 kHz频率范围内,利用平行板电极系统研究了果实采后成熟衰老过程中的电学特性,并对电学参数与果实品质的关系进行了分析.结果表明:随测定频率的增加,'嘎拉'苹果果实的复阻抗(Z)、并联等效电阻(Rp)、并联等效电感(Lp)和并联等效电容(Cp)均逐渐下降,而电导率(σ)却逐渐上升;0.1 kHz是'嘎拉'苹果果实电学特性检测的特征频率;并联等效电阻在0.1 kHz时与果肉硬度呈极显著正相关(r=0.986**)、与可滴定酸含量呈显著正相关(r=0.934*),可作为标志果肉硬度和可滴定酸含量的敏感电参数.研究发现,在特征频率下,并联等效电阻可以作为辨别'嘎拉'苹果果实品质变化的特征电参数.     

番茄果实中乙烯与多聚半乳糖醛酸酶的关系

乙烯与多聚半乳糖醛酸酶(PG)都是果实成熟过程中关键的调节因子.一方面,在有乙烯合成缺陷的转反义ACS番茄和乙烯感受缺陷的Nr突变体番茄果实中PG基因表达量都明显下降,PG酶活性明显降低;用外源乙烯(100 μL/L)处理绿熟期番茄果实使PG基因的表达明显增强,而1-甲基环丙烯(1-MCP,1 μL/L)处理转色期番茄果实明显抑制PG基因表达.另一方面,转反义PG基因番茄果实乙烯释放量在授粉后低于其野生型,番茄乙烯受体基因LeETR4和乙烯反应因子LeERF2基因表达量比野生种低.PG降解果胶的产物D-GA(100 mg/L)促进未熟期番茄果实中的乙烯生成和LeETR4、LeERF2基因的表达.     

骨骼肌细胞频响特性的数值分析

在100 Hz-100MHz频率范围内,利用非线性数值计算和曲线拟合分析,验证了蛙离体骨骼肌细胞的频率响应特性满足Cole-Cole公式(误差<3．45％),通过频域介电谱、 Cole-Cole图、介电损耗因子和介电损耗角正切频率谱的曲线拟合分析,确定了蛙骨骼肌细胞的 Cole-Cole参数:高频段相对介电常数εh=78,第一相对介电增量εt=113000,第二相对介电增量ε2=45000,第一特征频率fc1=9 KHz。第二特征频率fc2=158KHz,第一相位角β1=0．881,第二相位角β2=0．984,低频段电导率κ1=0．55mS／cm,A=35,m=1．08．     

SlCBL1基因调控番茄果实成熟发育的分子机理

以番茄(Solanum lycopersicum L.)品种‘Micro Tom’为试材,从其果实中克隆得到番茄类钙调磷酸酶B基因(Tomato Calcineurin B-Like gene,SlCBL1),构建其带有报告基因的e-GFP植物表达载体,分析番茄果实中SlCBL1基因超表达与成熟发育进程的相互关系。结果显示:(1)与对照非转基因植株以及转空载植株相比,转SlCBL1基因番茄中SlCBL1基因过量表达,而且能够使番茄果实成熟期提前3~5d,表明SlCBL1基因可促进番茄果实成熟。(2)番茄果实成熟相关基因的表达量也受到不同程度调控,其中番茄成熟过程中的色素合成基因、乙烯路径基因以及果实成熟相关转录因子都受到强烈的调控,与对照相比表达量分别上调5~10倍。研究表明,SlCBL1基因能够促进番茄果实成熟,而且通过影响色素合成基因以及果实成熟相关转录因子来调控番茄果实成熟。     

乙烯对番茄成熟过程中果皮细胞核超微结构的影响

应用冰冻蚀刻和透射电镜观察了番茄成熟过程中果皮细胞核染色质的变化。成熟过程开始启动时(发白期),异染色质不断减少、分散,直至转色成熟。果实成熟衰老时细胞核形态畸变,染色质结构瓦解。经外源乙烯处理后果实成熟加速,异染色质减少,核孔数量增加,NBD可消除乙烯的作用。     

果实特异性RNAi介导的Lcy基因沉默来增加番茄中番茄红素的含量

根据GenBank中番茄的番茄红素β-环化酶(Lcy)基因序列和八氢番茄红素去饱和酶基因(Pds)启动子序列设计特异引物从番茄基因组DNA中分别扩增出了Lcy基因的高度保守的长302bp的DNA片段和长1790的Pds启动子片段。根据RNAi的原理,将Lcy基因的DNA片段以正反两个方向通过一段内含子序列连接在一起形成RNAi片段,将该片段与Pds启动子一起插入到pVCT2020的表达载体中,通过农杆菌介导的方法转化番茄,获得转基因植株5棵,PCR检测证实外源片段已成功导入番茄基因组中。收获转色期后20d左右的完全成熟的番茄果实提取番茄红素进行含量分析,结果显示转基因番茄果实中番茄红素的含量极大的增加了。上述结果表明通过RNAi果实特异性的抑制类胡萝卜素代谢途径中生物合成酶基因的表达能够极大的增加番茄果实中番茄红素的含量。这为通过基因工程手段提高番茄果实中的营养价值提供了参考。     

SlCBL1基因在番茄抗灰霉病中的作用

以番茄(Solanum lycopersicum L.)品种‘Micro Tom’为试材,分析番茄叶片和果实的灰霉病发病规律,及番茄类钙调磷酸酶B基因(tomato calcineurin B-like gene,SlCBL1)在叶片和果实中的表达变化;比较转SlCBL1基因番茄与对照的叶片和果实的灰霉病发病过程,分析转基因番茄抗病相关转录因子表达变化。结果表明:(1)非转基因番茄中,不同叶龄的叶片均在接种灰霉病4d开始发病;不同发育阶段的果实接种灰霉病后发病时间也不同,其中绿果(花后16~18d)接种5d还未发病,白果(花后34~36d)接种11d开始发病,红果(花后40~42d)接种5d开始发病;SlCBL1基因表达量在番茄叶片中较低,在绿果期和白果期的果实中表达量最高,红果期果实中表达量最低。(2)转SlCBL1基因后,SlCBL1基因的过量表达能够抑制番茄叶片和果实灰霉病发生;同时番茄叶片和果实中几乎所有的抗病转录因子的表达量都上调,其中WRKY转录因子家族基因SlWRKY33和SlWRKY70受到强烈调控。研究说明,SlCBL1基因过量表达能够提高番茄的抗灰霉能力,其主要机理是通过影响抗病相关转录因子进而调控番茄抗灰霉病的能力。     

套袋遮光对欧李果实糖酸和类黄酮含量的影响

【目的】考察不同光照时间及强度对欧李果实糖酸和类黄酮含量的影响,为后期深入探讨光照影响果实品质的分子机制提供参考依据。【方法】以欧李品种‘农大6号’和‘农大7号’为试验材料,采用3种不同遮光率（30%、55%和100%）的果袋分别在果实膨大期和转色期进行套袋处理,测定其果实单果质量、可滴定酸含量、可溶性固形物含量和类黄酮含量。【结果】（1）两品种单果质量和果实可溶性固形物含量均表现为果实膨大期处理低于果实转色期处理,且均随着果袋遮光率的升高而逐渐降低。（2）‘农大6号’可滴定酸含量在套袋处理下均明显降低,且果袋遮光率越高、套袋时间越长,降酸效果越明显,而‘农大7号’可滴定酸含量受影响较小。（3）套袋‘农大6号’类黄酮含量均高于对照,并随着果袋遮光率的增加先升后降,且膨大期处理高于转色期处理。套袋‘农大7号’类黄酮含量仅在果袋遮光率30%时显著高于对照,且膨大期处理显著低于转色期处理,其含量随着果袋遮光率增加在膨大期逐渐增加,在转色期先降后升。【结论】套袋能有效改善欧李果实糖酸和类黄酮含量,‘农大6号’以膨大期套袋为宜,‘农大7号’则以转色期套袋效果更好,而且均以55%遮光率果袋对两品种糖酸和类黄酮含量综合改善效果最佳。     

番茄品种资源芽苗期和幼苗期的耐盐性及耐盐指标评价

对芽苗期和幼苗期番茄耐盐鉴定指标进行检验,明确番茄芽苗期和幼苗期耐盐性的相关性,筛选耐盐的番茄品种资源,以便为耐盐育种和栽培提供材料和方法.试验采用不同浓度的NaCl水溶液人工模拟盐胁迫,以多项指标盐害系数隶属函数值和总隶属函数值为依据,比较了20个番茄品种资源芽苗期和幼苗期的耐盐性及两个时期耐盐性的相关性,并利用单一指标盐害系数隶属函数值和总隶属函数值进行了聚类分类.结果表明:芽苗期和幼苗期番茄耐盐性有所不同,耐盐和中等耐盐材料相同率为53.85%.进行番茄耐盐性筛选时可以把发芽势、发芽率、发芽指数、萌发活力指数、下胚轴长、地上鲜重作为芽苗期耐盐鉴定指标,把地上部鲜重、根鲜重、地上部干重、根干重、壮苗指数、根/冠比作为幼苗期耐盐鉴定指标.     

果实特异性RNAi介导的Lcy基因沉默来增加番茄中番茄红素的含量

根据GenBank中番茄的番茄红素β-环化酶（Lcy）基因序列和八氢番茄红素去饱和酶基因（Pds）启动子序列设计特异引物从番茄基因组DNA中分别扩增出了Lcy基因的高度保守的长302bp的DNA片段和长1790的Pds启动子片段。根据RNAi的原理,将Lcy基因的DNA片段以正反两个方向通过一段内含子序列连接在一起形成RNAi片段,将该片段与Pds启动子一起插入到pVCT2020的表达载体中,通过农杆菌介导的方法转化番茄,获得转基因植株5棵,PCR检测证实外源片段已成功导入番茄基因组中。收获转色期后20d左右的完全成熟的番茄果实提取番茄红素进行含量分析,结果显示：转基因番茄果实中番茄红素的含量极大的增加了。上述结果表明：通过RNAi果实特异性的抑制类胡萝卜素代谢途径中生物合成酶基因的表达能够极大的增加番茄果实中番茄红素的含量。这为通过基因工程手段提高番茄果实中的营养价值提供了参考     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.