两种环缘蝽的染色体研究(半翅目:姬缘蝽科)

本文研究了中国姬缘蝽科开环缘蝽Stictopleurus punctatonervosus minutus Blote和闭环缘S．viridictatus(Uhler)的核型及其染色体的减数分裂行为．结果表明：两个种的染色体数目均为2n(♂)=13，具有一对m染色体和XO性别决定机制，但是在染色体行为方面却表现出了各自的特异性．     

缘蝽属的种类鉴别和分布(半翅目:缘蝽科)

本文记述了缘蝽科(Coreidae)的缘蝽属(Coreus Fabricius,1794)3种和1亚种的鉴别和分布。该属种类的某些主要鉴别特征、分布区和雄外生殖器的系统研究尚属首次报道。     

两种龟蝽的染色体研究(半翅目:龟蝽科)

研究了中国半翅目昆虫龟蝽科(Plataspidae)两个种——圆龟蝽属一种Coptosoma sp.和狄豆龟蝽Megacopta distnti(Momtandon)的核型及其染色体的减数分裂行为，结果表明：两个种的双倍染色体组成均为2n(♂)=12，具有X—Y性别决定机制，而且两个种的染色体在减数分裂中的行为均表现出了典型的蝽科特点，但每个种又有各自的特异性。     

秦巴山区缘蝽科分类初步研究(昆虫纲:半翅目异翅亚目:缘蝽科)

缘蝽科是半翅目异翅亚目(Hemiptera-Heteroptera)中的一个较大的科,我国记录有200多 种.该文针对秦岭及大巴山地区缘蝽科47个种的形态特征编写了种的检索表,并应用形态分类学 方法和SPSS软件进行了种间聚类分析.     

入侵害虫西部喙缘蝽和红肩美姬缘蝽在中国的潜在分布

为阻止入侵害虫西部喙缘蝽和红肩美姬缘蝽在中国大陆地区建立种群,对这2个物种在中国的生态适宜空间进行分析.基于文献资料构建西部喙缘蝽和红肩美姬缘蝽的分布数据库,即分别在二者的本土分布地区构建Maxent生态位模型,然后将模型转移并投射至东亚地区,对模型进行检验,进而预测这2种缘蝽在中国的适宜空间.研究结果表明:西部喙缘蝽和红肩美姬缘蝽在中国占有的生态空间较大,潜在地理分布范围较广.西部喙缘蝽的潜在分布区包括中国的中部地区及西南地区;红肩美姬缘蝽的潜在分布区包括中国中部及南部的大部分地区,东南沿海也具有较大的分布可能性.由此认为,中国中部沿海地区应加强西部喙缘蝽检疫,东南沿海地区应加强红肩美姬缘蝽检疫,防止这2种缘蝽在中国大陆地区建立种群.     

缘蝽科部分种类线粒体COII基因的分子系统学研究(半翅目:异翅亚目)

测定分析了缘蝽科18种昆虫COII基因部分片段,结果显示,T、C、A、G的平均含量分别为33.6%、16.4%、36.3%和13.7%.A+T平均含量达到69.9%,表现出较强的A+T含量偏向性.碱基替换中转换频率是颠换的1.1倍;转换的发生以T与C之间为主,颠换以T与A之间为主.从GenBank下载长蝽总科的Oncopeltus fasciatus和猎蝽总科的Triatoma dimidiata作为外群,建立缘蝽科17属18种间的系统发育关系.结果证明狭义巨缘蝽族为一个单系群,竹缘蝽族的两个属为一单系群,鼻缘蝽属与同缘蝽属亲缘关系非常近,环胫黑缘蝽(沟缘蝽亚科)和竹缘蝽族亲缘关系比较近,叶足特缘蝽和怪缘蝽亲缘关系较近.     

内蒙古苜蓿盲蝽属Adelphocoris Reuter的记述——(异翅亚目:盲蝽科)

本文首次对内蒙古苜蓿盲蝽属Adelphocoris Reuter 的17种昆虫进行了系统的记述,其中黑唇苗蓿盲蝽A.nigritylus Hsiao,三环苜蓿盲蝽A. triannulatus(Stal),光胸苜蓿盲蝽A.laeviusculus Vinokurov,中黑苜蓿盲蝽A.suturalis(Jakovlev),淡尖苜蓿盲蝽A.apicalis Reuter,淡缘苜蓿盲蝽A.luridus Reuter,短小苜蓿盲蝽A.ponghvariensis josifov 等7种为我区首次记录的害虫,四点褐苜蓿盲蝽A. piceosetosus Kulik 为中国新记录种。文中例出该属内蒙古种类分种检索表,并简要描述了上述新记录种的特征。     

猎蝽卵壳表面细微结构扫描电镜观察(半翅目：猎蝽科：真猎蝽亚科)

记述了我国的暗素猎蝽Epidaus nebulo(Stal)，六刺素猎蝽Epidaus sexspinus Haiao，红缘猛猎蝽Sphedanolestes gularis Hsiao，云斑瑞猎蝽Rhynocris incertus (Distant)，多变齿胫猎蝽Rihirbus strochantericus stal，利用扫描电镜分别对这些卵的卵壳表面及卵前极的细策结构进行了观察，比较，同时通过野外采集，饲养，记录了两个种的生物学特征，量度单位：mm。     

内蒙古盲蝽科国内新纪录属及一新种：半翅目：盲蝽科

记录了内蒙古半翅目盲蝽科(Hemiptera:Miridae)一国内新纪录属(斑腿盲蝽属Atomocelis Reuter,1875,包括亚洲斑腿盲蝽A.asi(?)ticus Josifov,1979和丰满斑腿盲蝽A.onustus(Fieber,1861)2个国内新纪录种)及该属一新种多毛斑腿盲蝽Atomocelis pubescens sp.n.     

广西六万林场蝽类优势种的发生与防治

2001至2003年，对广西六万林场蝽类的调查结果表明：大稻缘蝽、稻绿蝽、荔蝽和比蝽正陆生蝽的优势种。本文对这四种优势种的分布、形态特征、发生特点及危害习性进行了研究．并据此提出防治对策。     

In the platypus a meiotic chain of ten sex chromosomes shares genes with the bird Z and mammal X chromosomes

Two centuries after the duck-billed platypus was discovered, monotreme chromosome systems remain deeply puzzling. Karyotypes of males, or of both sexes, were claimed to contain several unpaired chromosomes (including the X chromosome) that form a multi-chromosomal chain at meiosis. Such meiotic chains exist in plants and insects but are rare in vertebrates. How the platypus chromosome system works to determine sex and produce balanced gametes has been controversial for decades. Here we demonstrate that platypus have five male-specific chromosomes (Y chromosomes) and five chromosomes present in one copy in males and two copies in females (X chromosomes). These ten chromosomes form a multivalent chain at male meiosis, adopting an alternating pattern to segregate into XXXXX-bearing and YYYYY-bearing sperm. Which, if any, of these sex chromosomes bears one or more sex-determining genes remains unknown. The largest X chromosome, with homology to the human X chromosome, lies at one end of the chain, and a chromosome with homology to the bird Z chromosome lies near the other end. This suggests an evolutionary link between mammal and bird sex chromosome systems, which were previously thought to have evolved independently.     

七星瓢虫精母细胞减数分裂观察研究

研究昆虫染色体一般选择在生殖细胞减数分裂阶段.七星瓢虫初级精母细胞的染色体计数为2n=16+X,减数分裂中期,n=8、n=8+X,染色体形态多为短棒状(参见照片).其性染色体是属XD型,雌性XX,为同配性别,雄性为异配性别,即X0(2n—1).昆虫染色体数量、组型,以及减数分裂的配对情况均与分类学亲缘关系有相关性,是昆虫正确鉴定和系统分类的重要参考.     

Rec8 phosphorylation and recombination promote the step-wise loss of cohesins in meiosis

During meiosis, cohesins--protein complexes that hold sister chromatids together--are lost from chromosomes in a step-wise manner. Loss of cohesins from chromosome arms is necessary for homologous chromosomes to segregate during meiosis I. Retention of cohesins around centromeres until meiosis II is required for the accurate segregation of sister chromatids. Here we show that phosphorylation of the cohesin subunit Rec8 contributes to step-wise cohesin removal. Our data further implicate two other key regulators of meiotic chromosome segregation, the cohesin protector Sgo1 and meiotic recombination in bringing about the step-wise loss of cohesins and thus the establishment of the meiotic chromosome segregation pattern. Understanding the interplay between these processes should provide insight into the events underlying meiotic chromosome mis-segregation, the leading cause of miscarriages and mental retardation in humans.     

Hypervariable telomeric sequences from the human sex chromosomes are pseudoautosomal

Pairing of human X and Y chromosomes during meiosis initiates within the so-called pairing region at the telomeres or the chromosome short arms. Using DNA from the Y chromosome we found sequence homology in the pairing region of the human X and Y chromosomes. This DNA is telomeric, contains repetitive sequences and is highly polymorphic in the population. The polymorphism has allowed family studies which show the sequences are not inherited as though linked to the sex chromosomes. This 'pseudoautosomal' pattern of inheritance points to an obligate recombination in the pairing region of the sex chromosomes during male meiosis.     

宝坻大蒜气生鳞茎和花粉母细胞发育的细胞学研究

为了从细胞学角度探讨大蒜的不育性,对宝坻大蒜气生鳞茎的发育、花粉母细胞的减数分裂过程及染色体的异常行为进行观察.结果表明:(1)大蒜的气生鳞茎数量多、长势快;(2)大蒜的花粉母细胞减数分裂过程中有27.4%的细胞出现异常分裂现象,包括滞后染色体(7.6%)、染色体桥(9.3%)、染色体断片(1.7%)和微核(9.7%)等异常行为;(3)正常发育的花粉母细胞在形成花粉粒时逐渐干枯.花粉母细胞中高频率的染色体结构变异和花粉母细胞在形成花粉粒时的干枯可能是导致大蒜不育的重要原因.     

Mediation of meiotic and early mitotic chromosome segregation in Drosophila by a protein related to kinesin.

Contrary to the traditional view that microtubules pull chromosomes polewards during the anaphase stage of meiotic and mitotic cell divisions, new evidence suggests that the chromosome movements are driven by a motor located at the kinetochore. The process of chromosome segregation involves proper arrangement of kinetochores for spindle attachment, followed by spindle attachment and chromosome movement. Mechanisms in Drosophila for chromosome segregation in meiosis differ in males and females, implying the action of different gene products in the two sexes. A product encoded at the claret locus in Drosophila is required for normal chromosome segregation in meiosis in females and in early mitotic divisions of the embryo. Here we show that the predicted amino-acid sequence of this product is related to the heavy chain of kinesin. The conserved region corresponds to the kinesin motor domain and includes the ATP-binding site and a region that can bind microtubules. A second region contains a leucine repeat motif which may mediate protein-subunit interactions necessary for attachment of chromosomes to the spindle. The mutant phenotype of chromosome nondisjunction and loss, and its similarity to the kinesin ATP-binding domain, suggest that the product encoded at claret not only stabilizes chromosome attachments to the spindle, but may also be a motor that drives chromosome segregation in female meiosis.     

Centromere inactivation in a dicentric rice chromosome during sexual reproduction

T0135 is a variant selected from the progeny of a rice line telotrisomic for the short arm of chromosome 11 （2n＋IIS＇）. Fluores- cent in situ hybridization （FISH） results indicated that T0135 contained two telocentric chromosomes, which have two centro- mere-specific molecular markers （5S rDNA） for chromosome 11; thus T0135 is a newly-described rice chromosome variant with two dicentric chromosomes, named 22＋11L-＋11L＇＋I IS.11S-＋I 1S-11S. （22 represents the 22 chromosomes excluding chromo- some 11 in the rice genome, ＂-＂ represents the centromere）. To investigate the genetic stability of the rice dicentric chromosomes during sexual reproduction, we observed the chromosome types in the progeny. Ninety-four percent of the progeny had the same chromosome type as the parental line. This result indicates that the dicentric chromosomes are mostly stable during mitosis and meiosis. Immunofluorescence analysis for centromere specific histone H3 （CENH3） revealed that only one centromere is active and the other centromere is inactivated in the rice dicentric chromosomes.     

Genetic evidence that a Y-linked gene in man is homologous to a gene on the X chromosome

The mammalian sex chromosomes are thought to be related to each other by sharing a common origin. That is, the X and Y chromosomes originally evolved from a pair of chromosomes that only differed at the locus determining sexual differentiation. For example, this evolutionary relationship is reflected during meiosis in chromosomal pairing between the tip of the human X chromosome short arm and the Y chromosome which presumably implies sequence homology. However, compelling genetic evidence for functional homology between the mammalian X and Y chromosome is lacking. We describe here the localization of a gene to the tip of the short arm of the human X chromosome and evidence for a related gene on the Y chromosome.     

Pre-meiotic S phase is linked to reductional chromosome segregation and recombination

Meiosis is initiated from G1 of the cell cycle and is characterized by a pre-meiotic S phase followed by two successive nuclear divisions. The first of these, meiosis I, differs from mitosis in having a reductional pattern of chromosome segregation. Here we show that meiosis can be initiated from G2 in fission yeast cells by ectopically activating the meiosis-inducing network. The subsequent meiosis I occurs without a pre-meiotic S phase and with decreased recombination, and exhibits a mitotic pattern of equational chromosome segregation. The subsequent meiosis II results in random chromosome segregation. This behaviour is similar to that observed in cells lacking the meiotic cohesin Rec8 (refs 3, 4), which becomes associated with chromosomes at G1/S phase, including the inner centromere, a region that is probably critical for sister-centromere orientation. If the expression of Rec8 is delayed to S phase/G2, then the centromeres behave equationally. We propose that the presence of Rec8 in chromatin is required at the pre-meiotic S phase to construct centromeres that behave reductionally and chromosome arms capable of a high level of recombination, and that this explains why meiosis is initiated from G1 of the cell cycle.     

Molecular cytogenetic analysis of Triticum aestivum-Leymus racemosus reciprocal chromosomal translocation T7DS·5LrL/T5LrS·7DL

In order to induce chromosome translocation between wheat chromosomes and chromosome 5Lr of Leymus racemosus, the mi- crosporocytes during meiosis of T. aestivum-L. racemosus disomic addition line DA5Lr were irradiated by 60Co γ-rays 800 R (100 R/min). Before flowering, the treated spikes were emasculated and bagged. After 2-3 d, the emasculated flowerets were pollinated using pollens from T. aestivum cv. Chinese Spring. One plant with two translocation chromosomes involved in both the long and short arm of...