红翅皱膝蝗减数分裂染色体的螺旋与轴结构

用低渗处理和苯酚品红染色,在经过卡诺液(甲醇3∶冰醋酸1)固定和未经固定的红翅皱膝蝗减数分裂染色体上都看到了螺旋结构。观察和测量结果表明,每条染色单体都是由430nm左右的染色线螺旋形成的。由染色线到染色体的压缩率为4∶1。低渗处理后固定的材料经过银染,则显示了染色体轴结构。同样,未经低渗处理直接固定的材料银染时也出现了轴结构。银染的轴结构位于每个染色单体的中央,并贯穿整个染色单体。在光镜下,这个轴并不是直径均一的棒状结构,而似乎是由许多大小相近的颗粒相连而成。本文对染色体结构的有关模型、骨架和轴结构的真实性以及轴和螺旋的关系等问题进行了讨论。     

大壁虎的染色体及减数分裂联会复合体的研究

大壁虎(Gekko gecko)的染色体数目为2n=38,核型由2对中着丝粒(Nos.1.4.)、3对亚中着丝粒(Nos.2.3.5)及14对端着丝粒和亚端着丝粒(Nos.6—19)染色体组成。一对核仁组织者(NOR_s),位于第7对端着丝粒染色体的末端。同时,本文还对大壁虎的减数分裂以及联会复合体(S.C)的结构和组型,进行了详细的观察和分析。     

长鬣蜥的染色体组型和减数分裂联会复合体的研究

本文报道长鬣蜥(Physignathus cocincinus)有丝分裂染色体及C-,Ag-带以及减数分裂联会复合体核型。染色体数2n=36,NF=48,核型组成为12V+24m(V为双臂大染色体,其中No.2为亚中着丝粒染色体,m为微小染色体)。结构异染色质主要分布在小染色体上。一对Ag-NORs分布于第2对亚中着丝粒染色体末端。     

甘宁地区蝗虫二新种（直翅目：斑翅蝗科）

本文记述采自甘肃和宁夏地区斑翅蝗科２新种,即小垫束颈蝗及暗翅皱膝蝗。     

联会复合体:减数分裂的结构基础

减数分裂是有性生殖生物产生单倍体配子的特殊分裂方式,其第一次分裂(减数分裂I)过程中同源染色体的行为是最突出的特征。在减数分裂I,同源染色体间形成的联会复合体通过促进和调控程序性DNA双链断裂的形成和修复,确保同源染色体正确的识别、配对、重组和分离,从而为减数分裂I的顺利完成提供保障。本综述对联会复合体的组成和功能研究进展进行了回顾,探讨了联会复合体的组装如何影响程序性DNA双链断裂的修复和交叉互换的形成,并总结了与人类生殖障碍相关的联会复合体成分突变,还对该领域未来研究方向进行了展望。     

雏蝗属黑翅亚属两种雏蝗染色体核型的比较研究

采用常规染色体制片方法,对雏蝗属黑翅亚属的黑翅雏蝗(Chorthippus(Megaulacobothrus)aethalinus(Zub.))和中华雏蝗(Ch.(M.)chinensis Tarb.)的染色体核型进行了分析比较,结果表明,两种雏蝗的染色体数目均为2n(♂)=17=16+XO;常染色体为中部着丝粒(m,6条)和端部着丝粒(t,10条)两种类型,性染色体类型为端部着丝粒,二者的相似性显示出该属的基本特征。但两种雏蝗的核型公式和染色体的相对长度组成则不相同,黑翅雏蝗K(2n,♂)=6m+11t=6L+6M+4S+XO;中华雏蝗K(2n,♂)=6m+11t=6L+8M+2S+XO。而且,二种雏蝗的性染色体位次及相对长度也有明显差异:黑翅雏蝗的性染色体位于第五位,相对长度为8.33%,而中华雏蝗的则位于第八位,相对长度为5.53%。由此看出,二种雏蝗不同物种间存在的不同遗传特征。     

雏蝗属与异爪蝗属二个近缘属蝗虫的染色体核型比较（直翅目：网翅蝗科）

采用常规染色体制片方法,对雏蝗属的模式种白边雏蝗Chorthippus albomarginatus(De Geer)和异爪蝗属的模式种素色异爪蝗Euchorthippus unicolor(Ikonnikov)的染色体核型进行了分析比较。结果表明,两种蝗虫的染色体数目均为2n(♂)=17=16+XO;常染色体为中部着丝粒(m,6条)和端部着丝粒(t,10条)两种类型,性染色体类型为端部着丝粒。二者的相似性显示出2属具有较近的亲缘关系,并且在进化过程中处于较近的发展阶段。但2种蝗虫的核型公式和染色体的相对长度组成则不相同,白边雏蝗K(2n,♂)=6m+11t=8L+4M+4S+XO;素色异爪蝗K(2n,♂)=6m+11t=8L+6M+2S+XO;且2种蝗虫性染色体的位次也有明显差别,白边雏蝗的性染色体为第9位,而素色异爪蝗则为第8位。由此看出,该2属的蝗虫存在的不同遗传特征。     

青海四种雏蝗染色体核型的比较分析

采用常规染色体制片方法对雏蝗属的褐色雏蝗Chorthippusbrunneus(Thunb .) ,异色雏蝗C .big uttulus(Linnaeus) ,小翅雏蝗C .fallax(Zub .) ,青藏雏蝗C .qingzangensis(Ying)的染色体核型进行分析 ,结果 :染色体数目均为 2n(♂ ) =1 7=1 6+XO ;常染色体类型为两类 ,中着丝点染色体 (m ,6条 )和端着丝点染色体 (T ,1 0条 ) ;性染色体类型为端着丝点。褐色雏蝗、异色雏蝗和青藏雏蝗的核型公式和染色体的相对长度组成为K( 2n ,♂ ) =1 7=6m +1 1T =6L +6M +4S +XO ,K( 2n ,♀ ) =1 8=6m +1 2T =6L +6M +4S +XX ;小翅雏蝗的为K( 2n,♂ ) =1 7=6m +1 1T =6L +4M +6S +XO ,K( 2n ,♀ ) =1 8=6m +1 2T =6L +4M +6S+XX。褐色雏蝗性染色体中部有次缢痕。染色体臂数 4种均为NF =2 3(♂ ) ,2 4 (♀ )。     

四种斑腿蝗科昆虫染色体带型的比较

应用染色体C带及银染核仁组成区定位分析方法对斑腿蝗科4种昆虫,即小蹦蝗属2种;峨眉小蹦蝗Pedopodisma emeiensis和秦岭小蹦蝗P.tsinlingensis;无翅蝗属2种;小无翅蝗Zubovskiaparvula和柯氏无翅蝗Z.koeppeni进行了研究,结果表明：4种蝗虫染色体数目（2n♂=21,XO)一致,小蹦蝗属M8染色体上具有端带;无翅蝗属X染色体具有特殊带纹,银染核仁组成区定位在两属各有特点,小蹦蝗属位于第8号染色体端部区域;无翅蝗属位于X染色体端部区域,除上述属内共性之外,各物种C带带纹又存在明显差异,其中峨眉小蹦蝗带型极为特殊。文中还对上述4种蝗虫带型结构特征及其进化意义作了讨论。     

中华鳖精母细胞联会复合体的研究

本文以微铺展技术制备中华鳖精母细胞联会复合体标本,经硝酸银染色后电镜观察,分析了SC组型。并与有丝分裂染色体组型相比较,发现二者有着良好的一致性,而且微小染色体的SC结构和着丝粒清晰,未发现形态上有分化的性染色体。中华鳖SC的研究为其细胞遗传学及性别决定机制提供了重要的依据。 Abstract　Synaptonemal Complexes (SC) in Trionyx sinensis spermatocytes prepared with micro-spreading technique and silver staining was analyzed by electron microscopy. The meiotic SC karyotype was constructed from 10 cells and compared with mitotic chromosome karyotype. There is a good agreement between them. The structure and kinetochores of micro-chromosomes are very distinctive on each SC. There does not exist differential sex chromosome.     

Synaptonemal complex karyotype of Eimeria tenella

In most organisms, biological variability rests on the behaviour of the chromosomes in the meiotic context. Despite the importance of meiosis, very little is known about the meiotic behaviour of the Eimeria chromosomes. The aim of the present study is to describe the standard synaptonemal complex karyotype from Eimeria tenella oocyst spreads by electron microscopy. For that purpose, complete sets of pachytene synaptonemal complexes were obtained and the morphological pachytene karyotype was determined. The authors used a previously reported method that overcomes the difficulty of the extreme resistance of protozoan oocysts to disruption and permits the release of intact meiotic chromosomes. The chromosomes were selected under a light microscope and those selected were stained with phosphotungtic acid and studied by transmission electron microscopy. The authors confirmed 14 chromosomes, which were observed as synaptonemal complexes, and the karyotype was constructed by arranging synaptonemal complexes according to their relative lengths and kinetochore position. Components of the synaptonemal complex, lateral elements, central element, recombination nodules and kinetochore were observed. Measures of the kynetochore, width of the synaptonemal complex, diameter of the recombination nodule and length of the telomeres are given. Minimal and no significant differences were found between measures of chromosomes isolated from different Eimeria tenella strains. To the best of our knowledge, the present investigation for the first time identifies and describes the morphological characteristics of the synaptonemal complex of Eimeria tenella during the meiosis that occurs within the oocysts. In addition, the authors provide evidence of the presence of recombination nodules, suggesting that the recombination process may play an important role in the molecular evolution of this parasite.     

The Synaptonemal Complex of Basal Metazoan Hydra:More Similarities to Vertebrate than Invertebrate Meiosis Model Organisms

The synaptonemal complex （SC） is an evolutionarily well-conserved structure that mediates chromosome synapsis during prophase of the first meiotic division. Although its structure is conserved, the characterized protein components in the current metazoan meiosis model systems （Drosophila melanogaster, Caenorhabditis elegans, and Mus musculus） show no sequence homology, challenging the question of a single evolutionary origin of the SC. However, our recent studies revealed the monophyletic origin of the mammalian SC protein components. Many of them being ancient in Metazoa and already present in the cnidarian Hydra. Remarkably, a comparison between different model systems disclosed a great similarity between the SC components of Hydra and mammals while the proteins of the ecdysozoan systems （D. rnelanogaster and C. elegans） differ significantly. In this review, we introduce the basal-branching metazoan species Hydra as a potential novel invertebrate model system for meiosis research and particularly for the investigation of SC evolution, function and assembly. Also, available methods for SC research in Hydra are summarized.     

Synaptonemal Complex Proteins: Specific Proteins of Meiotic Chromosomes

The review considers proteins of the synaptonemal complex (SC), a specific structure formed between homologous chromosomes in maturing germline cells during meiotic prophase I. The structure and functions are described for proteins that form ultrastructural SC elements in mammals, in yeast, and in higher plants. The roles of cohesins and of the SC proteins in meiotic sister-chromatid cohesion are considered. Though still scarce, data are summarized on the SC self-assembly and dissociation and on the molecular composition of SC-associated recombination nodules, which provide a compartment for meiotic recombination enzymes. The accumulating data on the SC molecular components and on their structure, properties, and interactions improve the understanding of the SC function.     

东北马鹿和东北梅花鹿F_1杂种精母细胞联会复合体分析

作者以界面铺张-硝酸银染色技术,对东北马鹿和东北梅花鹿的F_1可育杂种的精母细胞联会复合体进行亚显微观察及分析。在减数分裂前期,杂种鹿精母细胞中形成31条完整的常染色体联会复合体、一个端着丝粒染色体/中着丝粒染色体的三价体和XY双价体。这进一步证明,两种亲本鹿的染色体具有高度的同源性,其差别仅在于一个罗伯逊易位。三价体的顺式构型可能和杂种鹿的可育性有关。     

Meiotic prophase in diploid and tetraploid strains ofAllomyces macrogynus

Summary Three-dimensional serial section reconstructions of meiotic prophase nuclei ofAllomyces macrogynus (Chytridiomycetes, Blastocladiales) have been carried out. Serial section reconstructions of pachytene nuclei have revealed that the fungus when grown at 23 °C is an autotetraploid and is a diploid when grown at 35 °C for at least 6 months or on a substrate containing para-fluorophenylalanine for 1–2 weeks.Studies of the duplication and migration of the centrioles during the first stages of prophase revealed the existence of four centrioles in the 23 °C strain after centriole duplication and two centrioles in the 35 °C strain after duplication. It is observed that a bivalent attaches to the nuclear envelope at a site where a centriole is situated. It is proposed that the presence of the four centrioles in the 23 °C strain is due to the fact that each bivalent is represented twice in the strain.     

褐家鼠精母细胞中联会复合体的研究Ⅳ.常染色体联会复合体的发育和偶线期节的研究

采用表面铺展-SDS处理、硝酸银和磷钨酸（Phosphotungsticacid,PTA）染色电镜技术,研究了褐家鼠精母细胞中常染色体联会复合体（Synaptonemacomplex,SC）的发育及偶线期节（Zygotenenodule,ZN）。在褐家鼠精母细胞的细线期,常染色体轴心（Axialcores,ACs）已形成,同源轴心在空间上靠近,偶线期SCs开始形成,到粗线期SCs完全形成,于双线期SCs开始解体。在双线期除了个别SCs侧生组分分开外,大多数SCs发生碎片化（fragmentation）．在偶线期未配对的ACs和SCs侧生组分及中央组分上均发现电子密度高的球形或椭圆形的节状结构──偶线期节,ZNss在同源染色体配对过程中起很重要的作用。     

Damaging Effect of Antibiotics on the Structure of Synaptonemal Complexes of Meiotic Mouse Chromosomes

The structure of synaptonemal complexes (SCs) of chromosomes of mouse primary spermatocytes were studied using electron microscopy on days 1, 10, and 36 after the completion of per os administration of drugs belonging to three groups of antibiotics: tetracyclins, macrolides, and fluoroquinolones. The antibiotics were administered to mice during ten days. At the substages of early and middle pachytene, heteromorphic SC bivalents and fragments of chromosome-core elements were detected in spermatocytes at all times studied after the administration of the antibiotics of three groups. As cells passed through the period from early to middle pachytene, the number of cells containing heteromorphic SC bivalents and the fragments of axial cores gradually decreased, which could be an indication of selection of cells with chromosomal aberrations. A high level of associations between the X chromosome and autosome bivalents (including heteromorphic ones) also favors this suggestion. A gradual decrease in the number of chromosomal aberrations was detected, as time elapsed from the completion of antibiotics administration. The study of sperm obtained from epididymises of males did not reveal significant differences in both morphology and motility of sperm between males of the control and experimental groups.     

豚鼠精母细胞联会复合体的电镜观察

以微铺展法制备豚鼠精母细胞联会复合体标本,经硝酸银染色后作电镜观察,建立了SC组型．与有丝分裂染色体组型比较,发现二者有良好的一致性．在粗线期,X,Y轴的配对区很短,配对区的X轴和Y轴没有明显变细．未发现银染SC具有着丝粒,并对可能的原因作了分析讨论．