Photoreactivation of ultraviolet-induced chromosomal aberrations

Ultraviolet induces only chromatid-type aberrations in synchronized G(1) V-79 Chinese hamster and A8W243 Xenopus tissue culture cells. Posttreatment with white light prevents expression of most potential aberrations in the A8 toad cell, which possesses a photoreactivation enzyme. We conclude that the major ultraviolet-induced DNA lesion leading to chromosomal aberrations is the pyrimidine dimer.     

铅诱导蚕豆根尖细胞产生的各种染色体畸变研究

[目的]研究铅对蚕豆根尖细胞诱导产生的各种染色体畸变.[方法]用不同浓度的PbCl_2溶液培养蚕豆种子,以蒸馏水培养作为对照,培养4~7 d,每天随机取根尖固定、染色、压片后镜检,观察各种染色体畸变,并统计相应的数目.[结果]培养第4~7天,1.0×10~(-4)~5.0×10~(-4)mol/L Pb~(2+)处理组的各种染色体畸变数目都高于对照组的染色体畸变数目,且Pb2+浓度越大,染色体畸变数目越多.[结论]Pb~(2+)对蚕豆根尖细胞染色体畸变的影响程度与Pb2+处理浓度以及处理时间有关.     

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.     

Adaptive response of human lymphocytes to low concentrations of radioactive thymidine

When human lymphocytes were cultured with [3H]thymidine, which acts as a source of low-level chronic radiation, and then exposed to 150 rad of x-rays at 5, 7, 9, or 11 hours before fixation, the yield of chromatid aberrations was less than the sum of the yields of aberrations induced by [3H]thymidine and x-rays separately. Often fewer aberrations were found after exposure to radiation from both sources than were found after exposure to x-rays alone. At the same fixation times, nonradioactive thymidine did not affect the yield of x-ray-induced aberrations. The same phenomenon occurred at earlier fixation times, after exposure to 30 or 40 rad of x-rays and [3H]thymidine. This response is analogous to the adaptive response to alkylating agents whereby prior treatment with small doses for a long period reduces the damage occurring from large doses of similar agents given for a short time.     

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.     

阿拉尔垦区多异瓢虫色斑变异的研究

本文对采集于阿拉尔垦区7个团场的多异瓢虫色斑变异进行了研究，验证了文献［1］新近报道过的23种鞘翅色斑型，并观察到文献［1］未曾报道过的5种前胸背板色斑变异型和21种鞘翅色斑变异型，提出了自己的一些看法，为研究其它瓢虫色斑变异提供了有用的参考。     

人工诱导结瘤对烟草根尖细胞有丝分裂及染色体行为的影响

通过人工诱导烟草结瘤的方法,观察给予2,4-D、根瘤菌后,其对烟草根尖细胞有丝分裂和染色体畸变的影响.结果表明:在Jensen无氮营养液中,不论是只加2,4-D、根瘤菌,还是既有2,4-D又有根瘤菌,烟草根尖细胞有丝分裂指数在处理前期均有增加,其中以2,4-D和根瘤菌共同处理表现最为显著;但在处理的后期,细胞有丝分裂活动受到明显地抑制,并且伴有不同程度地染色体畸变.     

工业污染区繁缕微核的观察研究

[目的]了解工业污染区繁缕根尖细胞有丝分裂期染色体的畸变和微核。[方法]以兰州某工业污染区采的繁缕种子为材料,经过室温萌发,卡诺氏固定液固定,盐酸解离,石炭酸品红染色液染色,常规压片,镜检,进行微核鉴别。[结果]处理样品有丝分裂过程中存在着大量的染色体畸变,主要表现为微核的产生。在所观察的34个染色体畸变细胞中微核数有5种类型（8、9、10、11、12）,其中以微核数10和11的染色体畸变细胞为主。有染色体畸变的微核细胞小而圆,并且聚集成团出现,没有染色体畸变的正常细胞呈椭圆形,而且细胞较大。[结论]该研究为今后繁缕属植物的研究与环境污染的植物检测提供了参考。     

Mutagenic Action of Ethyl Methanesulfonate in Maize

Pollen of corn plants carrying three closely linked genes (alpha beta Sh(2)) on chromosome 3 were treated by ethyl methanesulfonate in order to determine the nature of genetic changes produced. In this genetic material the loss of the beta gene alone represents a discrete genetic change, possibly a point mutation, while the loss of two or more markers represents chromosome aberrations. Ethyl methanesulfonate, x-rays, and ultraviolet light all induced numerous chromosome aberrations, but only ultraviolet light and probably ethyl methanesulfonate induced discrete genetic changes.     

Cd~(2+)、Al~(3+)对蚕豆胚根根尖细胞遗传学毒性效应研究

以蚕豆(品种为8363)为供试材料,以不同浓度单金属离子Cd     

利用洋葱根尖微核技术对洗涤剂诱变效应的研究

根据微核技术原理,用6种不同浓度梯度的3种洗涤剂处理洋葱根尖细胞,对其遗传毒理学效应进行研究.结果表明:3种洗涤剂对洋葱根尖细胞都有不同程度的遗传损伤,其中分裂间期主要表现为微核、双核、核出芽以及核破裂;分裂期主要表现为染色体断片、粘连、滞后以及桥等遗传损伤效应.统计数据显示:用不同洗涤剂处理过的洋葱根尖细胞中,间期微核数、分裂期染色体桥、断片的细胞数以及有丝分裂指数均明显高于对照组,存在显著性差异.说明洗涤剂在一定程度上具有遗传毒性,其中洗衣粉的毒性最大,肥皂次之,香皂最弱.PI值显示洗涤剂在高浓度时均对水环境造成一定程度的污染.同时证明洋葱敏感度高,可以作为微核技术新的供试材料.     

接触二甲苯实验人员淋巴细胞染色体畸变分析

目的:研究二甲苯对实验人员外周血淋巴细胞染色体畸变的影响.方法:外周血培养制备染色体标本,分析外周血淋巴细胞染色体畸变.结果:二甲苯接触组的染色体数目畸变细胞率(11.3%)高于对照组(6.8%)(P＜0.05);结构畸变细胞率(包括裂隙)(3.57%)高于对照组(2.6%)(P＜0.05)并且呈剂量效应关系;接触组的未成熟着丝粒分离细胞率(1.85%)与对照组(1.34%)相比无显著差异(P＞0.05).结论:二甲苯接触导致外周血淋巴细胞染色体畸变增加;二甲苯接触是否诱导未成熟着丝粒分离有待进一步深入研究.     

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.     

Radiosensitization of X chromosome of Chinese hamster cells related to incorporation of 5-bromodeoxyuridine

Selective incorporation of 5-bromodeoxyuridine into the late replicating arm of the X chromosome of Chinese hamister cells cultured in vitro caused a selective radiosensization of the arm to ionizing radiation. Radiation damage was observed as chromosomal aberrations, and incorporation was studied by using tritiated 5-bromodeoxyuridine.     

丝裂霉素C诱发蚕豆染色体畸变的研究

本文报道了丝裂霉素C诱发蚕豆染色体畸变的效应。实验结果表明,丝裂霉素C诱发染色体畸变频率高于EMS,畸变类型也比EMS处理的多,因此,丝裂霉素C是一种高效化学诱变剂。     

Cytogenetic profiles of pigs transgenic for gene construct of human somatoliberin

The effect of integration of the human somatoliberin gene on the cytogenetic profiles of transgenic pigs is studied. A high level of chromosome variability of transgenic animals is established. The highest percentage of chromosome aberrations is found in transgenic animals of the second and third generations.     

Mycoplasma contamination of cultured amniotic fluid cells: potential hazard to prenatal chromosomal diagnosis

Amniotic fluid cell cultures were screened for mycoplasma contamination. Mycoplasma RNA's were observed in more than half the cultures examined. Karyotypic analyses of these contaminated cell cultures revealed a significant increase in chromosomal aberrations. These studies emphasize the need for screening for mycoplasma in cultured amniotic cells.     

Synergistic Effect of 5-Bromodeoxyuridine and Gamma Rays on Chromosomes

The combined effect of 5-bromodeoxyuridine and gamma rays on chromosomes in cells from the root tips of Zebrina pendula is synergistic. The enhanced, combined effects per cell of aberrations, bridges, and acentric fragments were, respectively, 2, 2.4, and 1.9 times the sum of the separate effects.     

Linkage group-chromosome correlation in Culex tritaeniorhynchus

Linkage groups of a culicine mosquito, Culex tritaeniorhynchus, have been assigned to their respective chromosomes by genetic and cytologic observations of radiation-induced aberrations. Linkage group I is assigned to the smallest chromosome, linkage group II to the submetacentric chromosome, and linkage group III to the metacentric chromosome.