Mutations, chromosomal aberrations, and tumors in insects treated with oncogenic virus

An increased incidence of lethal mutations, visible mutations, chromosomal losses, chromosomal nondisjunctions, and tumors resulted when drosophila were placed in medium containing Rous-sarcoma virus. In the group treated, a few mosaics of the eye and translocations appeared as well. There is a suggestion, from preliminary data, that the size of chromosomal puffs may be reduced by this RNA virus, but the difference is not significant. Tests for the persistence of virus in progeny have been negative so far.     

Chromosomal aberrations in a population of ground squirrels

Chromosomes were analyzed from a population of Spermophilus beldingi that included an adult female and three juveniles from the same burrow. All animals had a diploid number of 30. The adult and a juvenile female from the burrow had identical aberrant karyotypes containing an unpaired submetacentric and a minute metacentric chromosome. A familial aberration involving an X chromosome, without phenotypic alteration, is most probable.     

Chromosomal aberrations induced in barley by LSD

Seeds of hulled barley (Hordeum vulgare) were germinated and then treated with LSD. Preparations of squashed root tips stained with Feulgen revealed extensive chromosomal aberrations, most of which were chromosome breaks. Nearly half of the breaks occurred in the region of the primary constriction.     

The chromosomal basis of human neoplasia

High-resolution banding techniques for the study of human chromosomes have revealed that the malignant cells of most tumors analyzed have characteristic chromosomal defects. Translocations of the same chromosome segments with precise breakpoints occur in many leukemias and lymphomas, and a specific chromosome band is deleted in several carcinomas. Trisomy, or the occurrence of a particular chromosome in triplicate, is the only abnormality observed in a few neoplasias. It is proposed that chromosomal rearrangements play a central role in human neoplasia and may exert their effects through related genomic mechanisms. Thus, a translocation could serve to place an oncogene next to an activating DNA sequence, a deletion to eliminate an oncogene repressor, and trisomy to carry extra gene dosage.     

莲雾DNA的提取

针对莲雾体内含有大量影响DNA提取质量的多酚等次生代谢物质的特点,在常规提取方法的基础上做了技术改进,即加入PVP和β-巯基乙醇防褐变,成功地从叶片中提取染色体DNA,并可作为RAPD模板应用。     

大蒜体细胞无性系的染色体变异研究

5个大蒜品种经愈伤组织途径诱导再生植株形成体细胞无性系,对该无性系细胞进行染色体检查结果表明,通过愈伤组织培养诱导再分化形成的再生植株,其细胞染色体数目发生了不同程度的变异,5个品种的体细胞无性系二倍体率分别为52%,64%,58%,54%和62%,其余为多倍体、超倍体和亚倍体细胞。用苍山蒜和改良蒜的蒜基、蒜瓣和蒜叶分别作外植体培养形成的体细胞无性系二倍体率在46%～60%。检查还发现了染色体结构的变异。     

罗非鱼染色体组操作研究现状与展望

罗非鱼属鲈形目(Perciformes),丽鱼科(Cichlidae),约有700种,主要分布于非洲。按照Trewavas[1]分类法,可把罗非鱼分为3个属,即Tilapia属、Sarotherodon属和Oreochromis属。目前,有生产应用价值的主要是Oreochromis属的尼罗罗非鱼(O.niloticus)、奥利亚罗非鱼(O.aureus)以及莫桑比克罗非鱼(O.mossambicus)[2]。罗非鱼具有生长快、食性杂、繁殖快、产量高和味道鲜美而少刺等优良特征,近年来,全球罗非鱼养殖产量逐年递增,现已成为世界性主要养殖鱼类之一。这就迫使人们不断对养殖罗非鱼进行遗传改良,以防其种质退化。当前,国内外除了人工选…     

罗非鱼染色体组操作研究现状与展望

罗非鱼属鲈形目(Perciformes),丽鱼科(Cichlidae),约有700种,主要分布于非洲。按照Trewavas[1]分类法,可把罗非鱼分为3个属,即Tilapia属、Sarotherodon属和Oreochromis属。目前,有生产应用价值的主要是Oreochromis属的尼罗罗非鱼(O.niloticus)、奥利亚罗非鱼(O.aureus)以及莫桑比克罗非鱼(O.mossambicus)[2]。罗非鱼具有生长快、食性杂、繁殖快、产量高和味道鲜美而少刺等优良特征,近年来,全球罗非鱼养殖产量逐年递增,现已成为世界性主要养殖鱼类之一。这就迫使人们不断对养殖罗非鱼进行遗传改良,以防其种质退化。当前,国内外除了人工选…     

Extrachromosomal microDNAs and chromosomal microdeletions in normal tissues

We have identified tens of thousands of short extrachromosomal circular DNAs (microDNA) in mouse tissues as well as mouse and human cell lines. These microDNAs are 200 to 400 base pairs long, are derived from unique nonrepetitive sequence, and are enriched in the 5'-untranslated regions of genes, exons, and CpG islands. Chromosomal loci that are enriched sources of microDNA in the adult brain are somatically mosaic for microdeletions that appear to arise from the excision of microDNAs. Germline microdeletions identified by the "Thousand Genomes" project may also arise from the excision of microDNAs in the germline lineage. We have thus identified a previously unknown DNA entity in mammalian cells and provide evidence that their generation leaves behind deletions in different genomic loci.     

Avian v-myc replaces chromosomal translocation in murine plasmacytomagenesis

Deregulation of c-myc expression in association with chromosomal translocations occurs in over 95% of murine plasmacytomas, rat immunocytomas, and human Burkitt lymphomas. Infection with a murine retrovirus (J-3) containing an avian v-myc rapidly induced plasmacytomas in pristane-primed BALB/cAn mice. Only 17% of the induced plasmacytomas that were karyotyped showed the characteristic chromosomal translocations involving the c-myc locus. Instead, all of the translocation-negative tumors demonstrated characteristic J-3 virus integration sites that were actively transcribed. Thus, the high levels of v-myc expression have replaced the requirement for chromosomal translocation in plasmacytomagenesis and accelerated the process of transformation.     

河南地区中华大蟾蜍染色体核型分析

用植物凝集素、秋水仙素预处理的方法,取河南产中华大蟾蜍股骨骨髓细胞进行染色体标本制作,并对其核型进行初步研究分析。结果表明骨髓细胞分裂指数平均达到1.71%,二倍体染色体数目为2n=22=9m+2sm,含6对大染色体和5对小染色体,各对染色体之间在形态上可区分,且各具特色。与甘肃产中华大蟾蜍染色体相比,各染色体着丝点类型一致,除第4及第9染色体为亚中部着丝点染色体外,其余均为中部着丝点染色体,随体位于第6染色体末端。     

提取产气荚膜梭菌染色体DNA的新方法--氯化苄法

产气荚膜梭菌(Clostridium perfringens,又名魏氏梭菌Clostridium welchii)是广泛分布于土壤、大气、天然水域和正常动物肠道的一类温和厌氧菌.     

Reduced incidence of persistent chromosome aberrations in mice irradiated at low dose rates

A marked difference was observed between the effectiveness of high and low dose rates of ionizing radiation in producing persistent chromosome aberrations in the marrow cells of mice. Clones of cells with chromosome abnormalities were present in the marrow of all the mice previously exposed to single or fractionated doses of x-rays given at a rate of 30 rad/min. The frequency of chromosome aberrations in these mice varied from 14 to 72 percent of the cells exdmined. By contrast, none of the mice exposed to continuous gamma radiation at a low dose rate (1.45 rad/hour) showed definite clones of abnormal marrow cells, and the frequency of persistent chromosome aberrations varied from zero to 8 percent in this group.     

Chromosome segregation errors as a cause of DNA damage and structural chromosome aberrations

Various types of chromosomal aberrations, including numerical (aneuploidy) and structural (e.g., translocations, deletions), are commonly found in human tumors and are linked to tumorigenesis. Aneuploidy is a direct consequence of chromosome segregation errors in mitosis, whereas structural aberrations are caused by improperly repaired DNA breaks. Here, we demonstrate that chromosome segregation errors can also result in structural chromosome aberrations. Chromosomes that missegregate are frequently damaged during cytokinesis, triggering a DNA double-strand break response in the respective daughter cells involving ATM, Chk2, and p53. We show that these double-strand breaks can lead to unbalanced translocations in the daughter cells. Our data show that segregation errors can cause translocations and provide insights into the role of whole-chromosome instability in tumorigenesis.