关于额外小染色体起源的研究

在群体细胞遗传学的调查中发现了一例带有额外小染色体的家族。在该家族调查的3代人中有6名成员带有相同的额外小染色体,先证者与携带者的表型均正常。应用多种染色体显带技术对额外小染色体的性质做了深入研究,实验证明额外小染色体是具有双随体与双着丝粒的亚中部着丝粒染色体。依据研究结果对额外小染色体的起源做了分析,提出可能起源于D/G染色体短臂的罗伯逊易位。     

人微量全血培养与染色体标本制作技术研究

采用微量全血培养技术,培养人体外周血小淋巴细胞,使G0期白细胞重新进入细胞周期、增殖成功率高、技术方法完善。把体外增殖的小淋巴细胞裂解,对细胞核染色体进行染色和固定,制得人染色体标本,用于进行染色体组型分析．取得了令人满意的效果。     

巴西橡胶树HbRop基因家族5个成员的染色体物理定位

巴西橡胶中Rop家族基因能调控植物小G蛋白合成,是分子信号开关,参与橡胶树刮伤诱导乳管分化、防御胁迫应答和胶乳再生。为了揭示巴西橡胶树HbRop基因家族5个成员在细胞核染色体上的实际位置,展现家族基因之间的分布特点和连锁遗传关系,丰富橡胶树分子细胞遗传学信息,为橡胶树的分子辅助育种和比较基因组学研究提供分子细胞遗传学的科学理论依据。本研究以巴西橡胶树‘热研7-33-97’品种为材料将HbRop基因家族5个成员(HbRop1, HbRop2, HbRop3, HbRop4, HbRop5)定位在细胞核染色体上,通过双探针荧光原位杂交技术对橡胶树Rop小G蛋白基因家族5个成员在细胞核染色体上进行物理定位分析。实验结果表明:HbRop1基因定位在第1号染色体的短臂上,其信号位点到着丝粒的平均百分距离是63.34;HbRop2、HbRop3、HbRop4和HbRop5分别定位在第4、第3、第7和第10号染色体的长臂上,这些基因的信号位点到对应染色体着丝粒的平均百分距离分别是25.13、44.68、44.33和17.46,同时还讨论了它们与其他已定位的基因的位置关系。HbRop基因家族5个基因分别位于不同的染色体上,彼此间不存在连锁现象。     

Cucumis hytivus染色体组间交换重组及其对雄配子育性的影响

采用染色体压片技术对双二倍体种Cucumis hytivus染色体组间交换重组及其对雄配子育性的影响进行了细胞学研究。找到了该物种染色体组间交换重组的细胞学证据:包括前期的"8"字形、"十"字形结构和中期环状、链状多价体。研究还发现各种可能导致遗传物质不均衡分离的异常结构如染色体桥、染色体滞后、染色体组分离、微核等。染色体组间广泛的交换和重组导致约93%的多分体及部分异常四分体的形成,多分体中大量的畸形小孢子和四分体中遗传物质不平衡的小孢子因不能正常发育而最终形成败育的雄配子,直接影响到Cucumis hytivus育性。     

Cucumis hytivus染色体组间交换重组及其对雄配子育性的影响

采用染色体压片技术对双二倍体种Cucumis hytivus染色体组问交换重组及其对雄配予育性的影响进行了细胞学研究。找到了该物种染色体组间交换重组的细胞学证据：包括前期的“8”字形、“十”字形结构和中期Ⅰ环状、链状多价体。研究还发现各种可能导致遗传物质不均衡分离的异常结构如染色体桥、染色体滞后、染色体组分离、微核等。染色体组问广泛的交换和重组导致约93％的多分体及部分异常四分体的形成,多分体巾大量的畸形小孢子和四分体中遗传物质不平衡的小孢子因不能正常发育而最终形成败育的雄配子,直接影响到Cucumis hytivus育性。     

短角斑腿蝗(Catantops brachycerus Will.)自然群体中不等双价体的细胞学研究

在上海附近的佘山,发现短角斑腿蝗自然群体中的一些个体的第8染色体是不等双价体。该染色体的额外片段比较大,由异染色质组成,并在减数分裂中期I和X染色体一样呈现负异固缩现象。在带有这个额外片段的半合体减数分裂时,发现第一次都是均等分离。这个现象与所观察到的下列事实一致,就是这对异形染色体的着丝点与额外片段之间经常只出现一个交叉点,再一次证明交换与交叉一对一关系和交换先于交叉理论的正确性。有关这个片段的来源,从—些旁证指出有可能来自X染色体。 所分析的530个个体中,100个是半合体,3个是带有这个片段的纯合体,因而得知额外片段在群体中的频率为10%。统计分析表明这三种遗传型,即正常纯合体、半合体和额外片段纯合体的频率符合Hardy-Weinberg公式,而且在连续三个世代之间以及不同季节之间这些频率没有显著的变化。有关额外片段在群体中的平衡机制,我们认为有可能是选择对半合体有利而使这种染色体维持稳定的多态平衡。     

云南水稻品种冬糯的白叶枯病抗性基因定位研究——Ⅰ.抗病基因的初级三体分析定位

本文研究了云南稻品种冬糯对我国水稻白叶枯病(Xanthomonas campestris pv. oryxac)菌系“江陵691”的抗性遗传和抗病基因与初级三体额外染色体的关系。冬糯对白叶枯病菌系“江陵691"的抗性受一对隐性基因控制(xa-k);该抗病基因分别与Xa-a、xa-c、Xa-(?)、Xa-f和Xa-i不等位,并呈独立遗传;与Xa-g不等位,呈连锁遗传,重组值为28.7%。冬糯抗病基因与Triplo-7的额外染色体即第7染色体有关,推定冬糯所带的抗病基因位于第7染色体上。以IR36为遗传背景的初级三体系带有一对显性抗白叶枯病基因,该抗病基因位于第11染色体上。     

染色体黏合蛋白功能的多样性

染色体黏合是细胞分裂过程中由一环状蛋白复合物黏合素(cohesin)将染色体单体聚合在一起的细胞生物学过程,确保了染色体在后期的精确分离.除了黏合素,还有许多辅助因子共同参与组成染色体黏合蛋白家族,在染色体黏合的建立、维持及解离过程中发挥重要功能.此外,该家族蛋白还参与调控DNA损伤修复、基因表达以及染色质高级结构形成等事件.虽然染色体黏合蛋白的功能和调控机制在有丝分裂中得到了比较深入的研究,但其在减数分裂,特别是第一次减数分裂中的作用及机制还不完全明确.本文对染色体黏合蛋白在各种生物学事件中的功能进行了概述,尤其阐释了它们在生殖细胞减数分裂中的非经典作用,并探讨了该领域未来的发展方向.     

谷子 MADS-box基因家族的鉴定和表达分析

MADS-box基因是真核生物中一类重要的转录因子,参与调控多项植物的生长发育过程。然而关于谷子穗发育的MADS-box基因研究比较少。本研究使用序列相似性检索,在Phytozome 13.0数据库中筛选并且鉴定出了68个谷子MADS家族成员,并对这些家族成员的物理化学性质、系统发育树、染色体定位、表达谱等进行了全面的分析。结果表明,谷子MADS家族成员在染色体上分布不均匀,可以分为5个亚族。通过组织特异性表达谱分析得到,多数MADS基因在穗中表达量要高于其他器官。此外利用转录组测序技术对发育初期的谷穗和成熟期的谷穗进行了转录组测序分析,筛选到数个与谷穗分生组织发育相关MADS-box基因。为进一步揭示MADS-box基因在谷子穗发育过程中的作用奠定了重要的基础。     

食管癌遗传病因的研究——Ⅰ.林县食管癌高癌家族成员体细胞的染色体观察

从林县5个食管癌高癌家族成员103名及与之毗邻的4个低癌家族成员31名的淋巴细胞所作的染色体对比分析结果表明:高癌和低癌家族成员淋巴细胞染色体众数及其核型均属正常二倍体(2n=46)。但在高癌组中查到1.6％和3.25％具有染色体数目和结构异常的细胞,与低癌组比较有非常显著的差别(P<0.01)。核型分析发现有少数假二倍体、G组三体性和第2号染色体不配对现象。101个染色单体断裂主要集中在A、B、C三组,断裂部位长臂比短臂为多。对肿瘤发生中遗传和环境(内因和外因)因素的相互作用进行了讨论。     

Balanced translocation t(17p--; 23p+) in the chimpanzee]

A chimpanzee family was studied, in which the father had a balanced translocation t(17p--; 23p+). The mother showed the normal female chromosome complement. Their daughter had also the normal female karyotype, but with heteromorphic chromosomes 23. A cytogenetic analysis was made using G- and Q-banding techniques and in addition an alkaline silver method for NOR staining. A mechanism of the translocation inheritance is discussed.     

Detection of aneuploid cells in fibroblast cultures from the father of two trisomy 21 patients.

Karyotype analysis was performed on successive cultures of fibroblasts from the parents of two trisomic 21 patients. Starting from the 7th passage in the father cultures an aneuploid clone showing an extra E-like chromosome was found, which eventually overgrew the cell population. The significance of this cytogenetic finding is discussed in relation to the recurrence of the trisomy in the family.     

Phenotypic correlations in a patient with ring chromosome 22

Ring chromosome 22, a rare cytogenetic anomaly, has been described in over 60 cases in the medical literature. The aim of this report was to present a case carrying ring chromosome 22, and her family.It is a case report of a patient presented at Medical Faculty of ?ukurova University in Turkey.An 8-year-old girl with ring chromosome 22 and her family were evaluated cytogenetically and clinically.A chromosome analysis of the proband revealed a de novo 46, XX, r(22)(p11.2;q13) karyotype. Our subject demonstrated the prominent features of this syndrome including profound mental retardation, language impairment, dysmorphic features, lack of speech, hyperactivity, and behavioral disorders.There is lack of consistency between the physical abnormalities that we observed in our subject and those observed for such patients in the literature. The wide range of manifestations observed in patients with this cytogenetic alteration is probably due to size differences in the deleted region.     

Mitotic and polytene chromosomes analysis of the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

The Oriental fruit fly, Batrocera dorsalis s.s. (Hendel) is one of the most destructive agricultural pests, belonging to a large group of difficult to distinguish morphologically species, referred as the B. dorsalis complex. We report here a cytogenetic analysis of two laboratory strains of the species and provide a photographic polytene chromosome map from larval salivary glands. The mitotic complement consists of six chromosome pairs including a heteromorphic sex (XX/XY) chromosome pair. Analysis of the polytene complement has shown a total of five polytene chromosomes (10 polytene arms) that correspond to the five autosomes. The most important landmarks of each polytene chromosome and characteristic asynapsis at a specific chromosomal region are presented and discussed. Chromosomal homology between B. dorsalis and Ceratitis capitata has been determined by comparing chromosome banding patterns. The detection of chromosome inversions in both B. dorsalis strains is shown and discussed. Our results show that the polytene maps presented here are suitable for cytogenetic analysis of this species and can be used for comparative studies among species of the Tephritidae family. They also provide a diagnostic tool that could accelerate species identification within the B. dorsalis complex and could shed light on the ongoing speciation in this complex. Polytene chromosome maps can facilitate the development of biological control methods and support the genome mapping project of the species that is currently in progress.     

Identification,genomic organization and mRNA expression of CRELD1, the founding member of a unique family of matricellular proteins

We have isolated and characterized a unique gene that encodes a highly conserved membrane bound extracellular protein that defines a new epidermal growth factor-related gene family. The CRELD1 (Cysteine-Rich with EGF-Like Domains 1) gene (previously known as cirrin) was cloned from a human chromosome 3 BAC. Mapping of the gene confirmed its position at chromosome 3p25.3. The gene is ubiquitously expressed in early development and later becomes more markedly expressed in the developing heart, limb buds, mandible and central nervous system. Expression persists in adulthood in most tissues. Sequence analysis suggests that this is a cell adhesion protein. The mouse orthologue was cloned and mapped to the syntenic region of mouse chromosome 6. Orthologues or homologues have also been identified for cow, Chinese hamster, Drosophila and Caenorhabditis elegans. The CRELD1 gene is deleted in the human cytogenetic disorder 3p- syndrome and is in the region of loss of heterozygosity for several types of cancer. A potential role for this protein in these disorders is discussed.     

A family with Huntington disease and reciprocal translocation 4;5.

We report the clinical and cytogenetic findings in a family in which a balanced reciprocal translocation between the long arm of chromosome 4 and the short arm of chromosome 5 is segregating together with Huntington disease in 2 generations. In situ hybridization studies revealed that the linked human DNA marker is located on the short arm of the normal and translocated chromosome 4 in the region 4p16. The association between Huntington disease and the translocation in this family may represent a chance occurrence. However, it is also possible that there is an undetected rearrangement of DNA on chromosome 4 involving the gene for Huntington disease but not affecting the site of the linked marker. Finally, the likelihood that this represents heterogeneity cannot be excluded.     

Distal monosomy of the long arm of chromosome 6 (6q25----6qter) inherited by maternal translocation t(6q;17q)

Two half-sisters with distal monosomy of the long arm of chromosome 6 (q25----qter) inherited by maternal translocation t(6q;17q) were investigated. The clinical manifestations of these patients are compared with eight cases reported in the literature for further characterization of the 6q-syndrome. The cytogenetic diagnosis of alterations involving small chromosome fragments and the different origins of this type of deletion are also discussed.     

In vivo cytogenetics: mammalian germ cells

This chapter summarizes the most relevant methodologies available for evaluation of cytogenetic damage induced in vivo in mammalian germ cells. Protocols are provided for the following endpoints: numerical and structural chromosome aberrations in secondary oocytes or first-cleavage zygotes, reciprocal translocations in primary spermatocytes, chromosome counting in secondary spermatocytes, numerical and structural chromosome aberrations, and sister chromatid exchanges (SCE) in spermatogonia, micronuclei in early spermatids, aneuploidy in mature sperm. The significance of each methodology is discussed. The contribution of novel molecular cytogenetic approaches to the detection of chromosome damage in rodent germ cells is also considered.     

Characterization of a new aberration of the human Y chromosome by banding methods and DNA restriction endonuclease analysis

Summary Comparative cytogenetic analyses were performed with ten different banding methods on a previously undescribed, inherited structural aberration of a Y chromosome, and the results compared with those of normal Y chromosomes occurring in the same family. The value of the individual staining techniques in investigations of Y chromosomal aberrations is emphasized. The aberrant Y chromosome analyzed can be formally derived from an isodicentric Y chromosome for the short arm with a very terminal long-arm breakpoint, in which the centromere, an entire short arm, and the proximal region on one long arm was lost. This interpretation was confirmed by determining the amount of the two Y-specific DNA sequences (2.1 and 3.4 kb in length) by means of HaeIII restriction endonuclease analysis. The karyotype-phenotype correlations in the men with this aberrant Y chromosome, especially the fertility dysfunctions (oligoasthenoteratozoospermia, cryptozoospermia), are discussed. The possibility of the existence of fertility factors involved in the control of spermatogenesis within the quinacrine-bright heterochromatic region of the Y long arm is presented.     

Sex chromosome differentiation in Belostoma (Insecta: Heteroptera: Belostomatidae)

Belostoma, a genus of the family Belostomatidae, includes species of great ecological importance as biocontrol agents. Few species of these species have been the subject of cytogenetic analyses. Karyotypic evolution in this genus involves agmatoploidy and simploidy; there are also different sex chromosome systems. We examined two Belostoma species (B. dilatatum and B. candidulum) collected from the Paranapanema River Basin (Brazil). Mitotic and meiotic analysis revealed 2n(♂) = 26 + X(1)X(2)X(3)Y for B. dilatatum and 2n(♂) = 14 + XY for B. candidulum; both karyotypes have holokinetic chromosomes. Differences in heterochromatin distribution were also observed between the species, besides variation in the localization of CMA(3)(+)/DAPI(-) blocks. The existence of different types of sex chromosome systems in these species was confirmed based on arrangements of the chromosomes in different meiotic stages. We identified a new sex system in B. dilatatum, and make the first cytogenetic report on B. candidulum.