除虫菊和茼蒿核糖体ＤＮＡ ＩＴＳ区的序列

除虫菊(Pyrethrum cinerariifolium),又称白花除虫菊,是众所周知的著名杀虫植物,也是目前世界上唯一集约化栽培的天然杀虫剂原料,至今仍为肯尼亚、厄瓜多尔等一些国家的支柱产业。除虫菊的头状花序中含有6种0.4 %～2 %的杀虫成分,即除虫菊酯Ⅰ,Ⅱ(pyrethrin-I,II),瓜菊酯Ⅰ,Ⅱ(cinerin-I,II)和茉莉菊酯Ⅰ,Ⅱ(Jasmolin-I,II),6个成分组成的复合植物杀虫剂,对家蝇的杀虫活性LD50为15～20μg/g,对大白鼠的毒性LD50为2124～2416 mg/kg,对温血动物毒性更低。面对呼唤绿色产业的21世纪,除虫菊的产业开发又成为天然农药开发的一个热点。我们…     

抗苄呋菊酯淡色库蚊对其它拟除虫菊酯的交互抗性

1978年秋末从上海闸北区采得淡色库蚊用苄呋菊酯选育获得高达960倍的抗性品系(Res品系),它对被测定的其它拟除虫菊酯具有不同程度的交互抗性,抗性倍数从7倍(天然除虫菊酯)至7,342倍(戊氰菊酯)。交互抗性大于90倍以上的是醇部位中带有3-苯氧基苄基的二氯苯醚菊酯及其顺、反异构体或醇部位中带有`α``-氰基-3-苯氧基苄基的溴氰菊酯和戊氰菊酯。具有高抗性的4种杀虫剂(包括苄呋菊酯)分别与增效剂增效醚(Pb)或磷酸三苯酯(TPP)以1:1的比例混用后的结果表明,抗性机制与多功能氧化酶和酯酶皆有密切关系,但氧化酶抑制剂增效醚(Pb)的增效效果明显地要强于酯酶抑制剂磷酸三苯酯(TPP)的增效效果。     

白花除虫菊同源四倍体株系花期除虫菊酯含量及农艺性状分析

采用高效液相色谱法测定了16个白花除虫菊[Pyrethrum cinerariifolium（Trev．）Vis．]同源四倍体株系干花中的总除虫菊酯、总除虫菊酯Ⅰ（PyⅠ）和总除虫菊酯Ⅱ（PyⅡ）含量,并分析了16个同源四倍体株系花中总除虫菊酯含量的动态变化规律以及花期的农艺性状。结果表明,管状花开放初期,同源四倍体株系干花中的除虫菊酯含量最高,其中11个株系的总除虫菊酯含量高于二倍体株系且7个株系干花中的总除虫菊酯含量高于1．4％,达到一级花的质量标准。同源四倍体株系的花薹和花序的农艺性状表现出明显的多倍体性状,花薹低,花盘直径大,干花产量高,通过合理密植可以提高同源四倍体株系的干花产量。     

拟除虫菊酯的结构与害虫抗药性的关系

以家蝇Musca domestica vicina L.为试虫,用汰选方法研究了家蝇对六种不同拟除虫菊酯的抗性发展.结果表明,家蝇对不同化学结构和不同光学异构体组分的拟除虫菊酯抗性差别很大.对溴氧菊酯、顺式氯氰菊酯抗性发展很快,氯氰菊酯次之,氰戊菊酯、氰戍菊酯A和氰戊菊酯A_σ抗性发展较慢.用抗溴氰菊酯家蝇品系和点滴法测定了十种拟除虫菊酯和七种有机磷杀虫剂的毒力,讨论了它们之间的交互抗性和结构与抗性的关系.溴氰菊酯(抗性比值24.00)、氯氰嫡酯(抗性比值20.11)、顺式氯氰菊酯(抗性比值38.10)和二氯苯醚菊酯(抗性比值11.04),结构相近的交互抗性比较严重.氰戊菊酯(抗性比值4.64)、氰戊菊酯A(抗性比值5.97)、戊菊酯(抗性比值4.49)和氟氰菊酯(抗性比值4.12)化学结构中醇部分与溴氰菊酯相同、酸部分不同,它们与溴氰菊酯交互抗性水平较低.联苯菊酯(抗性比值1.98)化学结构中酯和醇部分都与溴氰菊酯不同,其交互抗性水平较低,杀螟松等七种有机磷杀虫剂,除敌敌畏与溴氰菊酯有轻微交互坑性外,其它均无交互抗性.     

某些杀虫剂对数种寄生蜂的触杀活性

以不同类型的十三种杀虫剂对菜田三种寄生蜂(凤蝶金小峰、菜粉蝶绒茧蜂和啮小蜂)进行了室内触杀活性研究.拟除虫菊酯类杀虫剂对寄生蜂的击倒速度,通常较有机磷制剂快,但其杀虫活性较有机磷制剂小.在四种拟除虫菊酯中,杀灭菊酯和中西除虫菊酯对凤蝶金小蜂的毒性,较氯氰菊酯和二氯苯醚菊酯小.马拉硫磷对凤蝶金小蜂的击倒速度最快.乙酰甲胺磷等七种有机磷制剂对凤蝶金小蜂的活性都很大.微生物制剂浏阳霉素对凤蝶金小蜂无杀虫活性,但和乐果复配后.杀虫活性明显增加.在试验条件下,凤蝶金小蜂接触4.35×10^-4毫克/平方厘米药膜后,开始击倒的速度顺序为:马拉硫磷>氯氰菊脂二氯苯醚菊酯>中西除虫菊酯>敌百虫氧化乐果>甲胺磷>乙酰甲胺磷;活性顺序为:氧化乐果>马拉硫磷甲胺磷>敌百虫乙酰甲胺磷>氯氰菊酯二氯苯醚菊酯>中西除虫菊酯.杀灭菊酯对菜粉蝶绒茧蜂的击倒速度较三唑磷快,但活性较三唑碟小.杀灭菊酯和中西除虫菊酯对菜粉蝶绒茧蜂的重寄生蜂啮小蜂的活性较三唑磷小.接触拟除虫菊酯后,个别中寄或死亡的风蝶金小蜂和啮小蜂,有缓解现象.     

喜树开花特性及繁育系统的研究

定位观测了喜树(Camptotheca acuminata Decne)花部构造、开花特性,用杂交指数(OCI)、花粉/胚珠比(P/O)、去雄、套袋、人工授粉等方法测定了喜树的繁育系统.结果表明:喜树花序为由4～6个头状花序组成的聚伞花序,聚伞花序上部的头状花序由两性花组成,下部的花序由雄花组成,两性花雌雄蕊发育正常,雄蕊10枚,雌蕊1枚,下位子房,一室,倒生胚珠;雄花雄蕊发育正常,雌蕊不发育.自然条件下,同一头状花序散粉后2 d,花粉活力最高;两性花在柱头外翻后3～4 d,柱头可受性最强,第6天失去可受性.喜树两性花为半同步雌雄蕊异熟类型,每个头状花序的所有小花同步开放,雄蕊先成熟,表现为雄性时期,雄蕊脱落后,雌蕊成熟,表现为雌性时期,上一级头状花序雌蕊成熟期与下一级头状花序雄蕊成熟期重合.繁育系统检测结果为部分自交和异交,需要传粉者活动才能完成授粉过程.     

白花除虫菊叶绿体基因组特征及系统发育研究

白花除虫菊(Tanacetum cinerariifolium)是全球唯一集约化种植的杀虫园艺作物,从其头状花序提取的天然除虫菊酯广泛应用于有机农业和家居害虫防控,具有极高的商业价值。本研究通过Illumina HiSeq 2500测序平台对白花除虫菊叶绿体基因组进行了测序,并对其结构特征及系统进化关系进行了分析。结果表明,白花除虫菊叶绿体基因组为典型的四分体结构,基因组大小为150 171 bp,包括84个蛋白质编码基因、 37个转运RNA基因和8个核糖体RNA基因;密码子偏好性分析发现其叶绿体基因组中密码子末端偏好以A和U结尾,其中亮氨酸的密码子是最常用的,其使用UUA密码子的频率最高,RSCU值为1.88。在其叶绿体基因组中鉴定到简单重复序列(simple sequence repeat, SSR)位点共41个,包含37个单核苷酸重复序列、 4个复合型核苷酸重复序列;基于菊科(Asteraceae)39个叶绿体基因组序列构建的系统发育树表明,其叶绿体基因组高度保守,除近缘红花除虫菊(T.coccineum)外,除虫菊类与同为菊科的植物蒿子杆(Ismelia carinata)亲缘...     

棉铃虫对拟除虫菊酯抗性稳定性研究

研究棉铃虫Helicoverpa armigera (Hubner)对三种拟除虫菊醌（氰戊菊酯、溴氰菊酯、功夫菊酯)的抗性稳定性及敏感性恢复表明,即使棉铃虫对氰戊菊酯的抗性达到3166.3倍以上,抗性仍不稳定,经14代室内饲养后抗性下降为61.4倍;对一系列田间抗性种群的抗性稳定性研究后发现,棉铃虫对这三种拟除虫菊酯的抗性不稳定,在没有杀虫剂选择的情况下,开始几代抗性下降较快,当下降到一定水平(2～9倍)后,抗性比较稳定,很难完全恢复对拟除虫菊酯的敏感性。     

棉铃虫对拟除虫菊酯杀虫剂敏感性的修复及其乙酰胆碱酯酶的变化

利用生物测定和生物化学方法研究了抗药性棉铃虫Helicoverpa armigera(Hubner)对拟除虫菊酯敏感性修复及其体内乙酰胆碱酯酶的变化,结果表明：当去除药剂选择压后,棉铃虫对拟除虫菊酯的抗性为不稳定。随着停止用药的时间加长,敏感性增加。从田间收集的棉铃虫在室内饲养后第1代对拟除虫菊酯的抗性下降速度较迅速。特异性酶抑制剂对敏感和抗性棉铃虫种群的乙酰胆碱酯酶亲和力试验结果证实,乙酰胆碱酯酶在抗性棉铃虫对杀虫剂反应发生变化的过程中发生改变,这种酶的改变可能对棉铃虫抗药性的不稳定性有重要影响。     

拟除虫菊酯抗性家蝇的交互抗药性研究

拟除虫菊酯的广泛使用使家蝇普遍产生了抗药性,为有效的控制家蝇的危害,需要了解家蝇对轮换或新杀虫剂的交互抗性状况。作者用点滴法测定了两个实验室汰选的拟除虫菊酯抗性家蝇品系对几种杀虫剂的交互抗性,结果表明:二氯苯醚菊酯和溴氰菊酯之间存在较高程度的交互抗药性;拟除虫菊酯抗性较高的家蝇对作用机制不同的新农药(多杀菌素、氟虫腈)表现较低程度的交互抗性。     

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.