低温胁迫对不同基因型小麦品种光合性能的影响

选用不同基因型小麦品种(春性品种扬麦18、弱春性品种郑麦9023、半冬性品种烟农19),研究了分蘖期和拔节期低温对叶片光合和叶绿素荧光特性的影响.结果表明:分蘖期-10℃低温处理后,烟农19的净光合速率(Pn)、气孔导度(gs)、PSⅡ最大光化学效率(Fv/Fm)、光化学猝灭系数(qP)、非光化学猝灭系数(NPQ)和PSⅡ非循环光合电子传递速率(ETR)显著高于扬麦18和郑麦9023;郑麦9023的gs、Fv/Fm、qp和NPQ显著高于扬麦18,胞间CO2浓度(Ci)显著高于烟农19;扬麦18的Ci显著高于烟农19,初始荧光(Fo)显著高于郑麦9023和烟农19.拔节期0℃低温处理后,烟农19的Pn、gs、Fv/Fm和qP显著高于扬麦18和郑麦9023,NPQ和ETR显著高于扬麦18;郑麦9023的Pn、gs、Fv/Fm和qP显著高于扬麦18,Fo显著高于烟农19;扬麦18的Ci和Fo显著高于郑麦9023和烟农19.分蘖期和拔节期低温胁迫下,半冬性品种烟农19具有较高的光合活性和较强的自我保护机制,弱春性品种郑麦9023次之,春性品种扬麦18最低.     

糯大麦与非糯大麦颖果发育过程的解剖学与组织化学研究

为了明确糯大麦与非糯大麦颖果发育的差异,该研究以糯大麦代表性品种(‘白青稞’、‘甘垦5号’)和非糯大麦代表性品种(‘扬农啤10号’和‘苏裸麦1号’)为材料,采用体视显微镜观察、组织化学染色、树脂半薄切片和光学显微镜观察等方法,比较研究了糯大麦与非糯大麦颖果及其胚乳淀粉体发育的过程。结果显示:(1)糯大麦和非糯大麦颖果的形态变化,以及鲜、干重和含水率等的变化规律基本一致,生长曲线均呈"S"型。(2)两类大麦颖果胚乳和果皮的I2/KI染色结果不同,糯大麦胚乳的I2/KI染色结果为红褐色,其果皮被染为蓝黑色,而非糯大麦胚乳和果皮均被I2/KI染成蓝黑色,表明糯大麦和非糯大麦的颖果果皮里直链淀粉含量都较高,且糯大麦胚乳内以支链淀粉为主,而非糯大麦的胚乳内以直链淀粉为主。(3)糯大麦胚乳淀粉体的出现时间早于非糯大麦,且其中小淀粉体的比例高于非糯大麦,淀粉体充实状况也好于非糯大麦。(4)与非糯大麦相比,糯大麦表观直链淀粉以及总淀粉含量较低,但可溶性糖含量较高。研究表明,糯大麦颖果生长规律与非糯大麦类似,但内含物淀粉的积累规律不同。     

春性和半冬性小麦植株氮素积累与运转特征差异

以江苏省6个半冬性和9个春性小麦品种为材料,研究两类型小麦品种在大田条件下的氮素积累、运转和分配差异.结果表明: 施氮量相同条件下,半冬性小麦群体植株平均氮素积累量在越冬始期-拔节期低于春性小麦群体,孕穗期-成熟期高于春性小麦群体;氮素阶段累积量在越冬始期-拔节期两类型群体间差异不显著,开花-成熟期半冬性群体显著高于春性群体.半冬性小麦平均总氮素转运量、花后积累量显著高于春性小麦;两种类型小麦总氮素转运率、积累氮贡献率、总转运氮贡献率差异均不显著.半冬性小麦营养器官中叶片氮素转运量、转运率、转运氮贡献率均低于春性小麦,茎鞘氮素转运量、转运率、转运氮贡献率则高于春性小麦,茎鞘氮素转运量差异达显著水平;同一类型内不同品种间植株氮素积累量、总氮素运转量、花后氮素积累量、总氮素转运率、总转运氮贡献率等均存在差异.生产中应根据不同品种吸收、利用、运转氮素能力的差异,合理运筹生育期氮肥用量和施用比例,提高氮肥利用率.     

小麦籽粒发育及淀粉晶体特性对花后高温胁迫的响应

选用2个品质类型和成熟期不同的新疆主栽小麦品种‘新春11号’和‘新春39号’,分别进行花后灌浆早期高温(花后5~8d,32℃,T_1)和中期高温(花后15~18d,38℃,T_2)处理,分析花后高温对小麦籽粒发育及淀粉晶体的影响。结果显示:(1)T_1处理明显降低了两品种籽粒长度和粒重,而T_2处理显著影响籽粒宽度和厚度;高温处理虽然降低了籽粒灌浆速率,但两品种灌浆最大峰值出现时间均在花后18d。(2)T_1处理对小麦籽粒A型淀粉粒形态的影响较大,中熟品种‘新春11号’的A型淀粉粒表面在花后10d时可观察到微孔,在花后15~20d时其粒径明显小于同期对照,在花后20~25d时淀粉粒表面压痕增多且A、B型淀粉粒表面出现明显缢缩;而早熟品种‘新春39号’淀粉粒形态和粒径大小受花后高温的影响相对较小。(3)两品种在不同高温处理下,其淀粉粒晶体特性衍射峰出现的位置相同,但淀粉粒的尖峰强度不同,表明高温胁迫不影响淀粉粒的晶体类型,但可能改变了淀粉粒内部的层状结构。研究表明,花后早期高温不仅对小麦籽粒外部形态有较大的影响,同时也影响到籽粒内部淀粉粒的形态和晶体的特性。     

暖冬条件下播期对不同类型小麦幼穗分化的影响

对3个不同类型小麦品种在不同播期下的幼穗分化进程及受冻情况进行了系统观察和研究。结果表明,在气候变暖,秋、冬温度较高的情况下,小麦幼穗分化进入各时期的时间早晚为强春性品种>春性品种>半冬性品种;播期对小麦幼穗分化的伸长期、单棱期和二棱期持续时间长短影响较大;在早播的情况下。春性越强的小麦品种,越冬前幼穗分化发育速度越快,达到的发育阶段越高,越冬期间越容易被冻死。据此,提出在河南气候变暖,秋、冬温度较高的情况下,首先在生产上要选用半冬性品种,适当搭配晚播早熟的春性品种;其次,无论半冬性品种或春性品种。播种期都不宜过早。     

粒重差异显著的两种水稻颖果发育比较

为了探讨控制水稻(Oryza sativa L.)颖果发育的因素,选择了颖果干重有显著差异的Ootikara (大粒,36mg/粒)和Habataki (小粒,18 mg/粒)两个水稻品种,比较颖果重量、胚乳细胞数、果皮和胚乳的结构以及某些生理活性等变化。结果指出:与Habataki相比, Ootikara子房壁细胞和颖果的持续生长期长,最终颖果的胚乳细胞数目和每个细胞的平均干重大; Ootikara颖果的脱氢酶和H2O2酶活性、穗的呼吸速率、剑叶的绿色程度和光合速率等维持高水平的时间长;Ootikara子房背部维管束失去功能的时间也较迟。结果表明,大粒品种的库容大和生理活性期长是其颖果能显著增大的生理原因。     

粒重差异显著的两种水稻颖果发育比较

为了探讨控制水稻(Oryza sativa L.)颖果发育的因素,选择了颖果干重有显著差异的Ootikara(大粒,36mg/粒)和Habataki(小粒,18 mg/粒)两个水稻品种,比较颖果重量、胚乳细胞数、果皮和胚乳的结构以及某些生理活性等变化.结果指出:与Habataki相比,Ootikara子房壁细胞和颖果的持续生长期长,最终颖果的胚乳细胞数目和每个细胞的平均干重大;Ootikara颖果的脱氢酶和H2O2酶活性、穗的呼吸速率、剑叶的绿色程度和光合速率等维持高水平的时间长;Ootikara子房背部维管束失去功能的时间也较迟.结果表明,大粒品种的库容大和生理活性期长是其颖果能显著增大的生理原因.     

FACE条件下大气O3浓度增高对小麦剑叶光合色素含量的影响

应用FACE研究平台,采用烟农19、扬麦16、嘉兴002、扬麦15和扬辐麦2号等5个小麦品种,以O3自然浓度为对照,研究了大气O3浓度增高50％对不同小麦品种剑叶光合色素含量的影响.结果表明:开放式大气O3浓度增高条件下,小麦剑叶叶绿素a(Chl a)、叶绿素b(Chl b)、叶绿素总量Chl(a+b)和类胡萝卜素含量在孕穗期和开花期与对照差异不显著,而花后各时期均不同程度的降低,其中,Chl a、Chl b和Chl(a+b)含量下降达显著水平,说明大气O3浓度增高对叶绿素合成影响较小,但加速了其衰降过程.不同品种小麦剑叶光合色素含量对大气O3浓度增高的反应存在基因型差异,扬麦15和嘉兴002对大气O3浓度增高的敏感性弱于扬麦16、扬辐麦2号和烟农19.在籽粒灌浆盛期(花后21 d左右),剑叶Chl a、Chl b和Chl(a+b)含量与千粒重呈显著正相关.     

FACE条件下大气O3浓度增高对小麦剑叶光合色素含量的影响

应用FACE研究平台,采用烟农19、扬麦16、嘉兴002、扬麦15和扬辐麦2号等5个小麦品种,以O₃自然浓度为对照,研究了大气O₃浓度增高50%对不同小麦品种剑叶光合色素含量的影响.结果表明：开放式大气O₃浓度增高条件下,小麦剑叶叶绿素a (Chl a)、叶绿素b (Chl b)、叶绿素总量Chl(a+b)和类胡萝卜素含量在孕穗期和开花期与对照差异不显著,而花后各时期均不同程度的降低,其中,Chl a、Chl b和Chl(a+b)含量下降达显著水平,说明大气O₃浓度增高对叶绿素合成影响较小,但加速了其衰降过程.不同品种小麦剑叶光合色素含量对大气O₃浓度增高的反应存在基因型差异,扬麦15和嘉兴002对大气O₃浓度增高的敏感性弱于扬麦16、扬辐麦2号和烟农19.在籽粒灌浆盛期(花后21 d左右),剑叶Chl a、Chl b和Chl(a+b)含量与千粒重呈显著正相关.     

小麦颖果果皮绿色层内同化物的合成与分配

小麦幼嫩颖果中,果皮内侧发育出由内表皮与亚表皮组成的一薄层绿色组织。显微与亚显微结构观察表明,虽绿色层只接受到自然光照的1/4～1/8,叶绿体仍能正常发育,叶绿素含量与叶绿体数量均高出旗叶。大量胞间连丝联接相邻的绿色细胞,并在一定时期形成开放的胞间通道,显然有利于同化物的快速胞间运输。离体颖果饲喂~14CO_2试验证明,新合成的同化物从绿色细胞输向胚珠。绿色层产生的同化物可能通过合点端的珠心进入胚乳或通过珠孔直接汇聚到胚珠和分化中的原胚。     

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.