60Co线引起伤害真厉螨染色体畸变的研究

本文首次报道用60Coγ线照射一种地革螨-上海真厉螨引起的染色体畸变的研究.用60Coγ线(剂量1-50Krad)照射雌性革螨,引起的染色体裁畸变类型有: 染色提裂隙、断片、微小体、环形染色体、粉碎化和多倍体,染色体断片是最常见的畸变类型,并观察到微核的形成。染色体畸变率随照射剂量增加而增高,辐射剂量与畸变率之间存在密切相关（相关系数为0.85, P<0.025), 配得曲线回归方程为Y=3.27+14.49lg(X+1).     

60Coγ射线辐射中国水仙的细胞学诱变效应

用60Coγ射线辐射中国水仙三年生鳞茎,首次研究了辐射后中国水仙鳞茎M1代形态损伤、剂量效应曲线、细胞学变化及其与形态变化的关系。结果表明,60Coγ射线抑制细胞分裂,降低细胞分裂指数,引起中国水仙的形态损伤,并诱发中国水仙染色体畸变和核畸变,畸变类型丰富。在染色体畸变中染色体桥的发生频率较高,随着辐射剂量的增加染色体断片率提高。细胞核畸变中,微核发生率最高。核畸变率、染色体畸变率与剂量间存在显著的线性正相关,相关系数分别为0.9874、0.9829,线性方程表达式分别为Y=-0.085 1.0385X,Y=-9.6727 2.3697X。间期细胞微核率与分裂期染色体畸变率间呈正相关。     

提高辐射诱变育种效果及辐射遗传效应的研究：Ⅲ作物辐射遗传效应 …

试验结果证明：１．γ辐射处理可导致水稻和蚕豆芽中可溶性蛋白质与同工酶谱的变化;２．γ射线诱发蚕豆根尖细胞畸变率、断片率、微核率、染色体畸变率与辐照剂量的关系均符合模式Ｙ＝ａ＋ｂｘ＋ｃｘ＾２,呈抛物线变化趋势;３．微核率、断片率与核畸变率、染色体畸变率呈正相关。从而作者认为微核率、断片率可以作为检测染色体辐射效应的可靠指标;４．γ射线照射可引起蚕豆根尖细胞染色体带型的变化。     

提高辐射诱变育种效果及辐射遗传效应的研究Ⅲ作物辐射遗传效应的研究

试验结果证明：１．γ辐射处理可导致水稻和蚕豆芽中可溶性蛋白质与同工酶谱的变化;２．γ射线诱发蚕豆根尖细胞畸变率、断片率、微核率、染色体畸变率与辐照剂量的关系均符合模式Ｙ＝ａ＋ｂｘ＋ｃｘ￣２,呈抛物线变化趋势;３．微核率、断片率与核畸变率、染色体畸变率呈正相关。从而作者认为微核率、断片率可以作为检测染色体辐射效应的可靠指标;４．γ射线照射可引起蚕豆根尖细胞染色体带型的变化。     

~(60)Co-γ射线对唐菖蒲染色体的影响

4组各 16枚唐菖蒲种球分别经 4kγ、8kγ和 15kγ剂量60 Co -γ射线照射后培养根尖 ,组织学制片 ,盐酸地衣红染色 ,光学显微镜观察。结果表明 ,与对照组相比 ,经过照射的样本细胞内具有染色体桥、核空泡化、落后染色体等染色体畸变现象 ,其中 4kγ - 8kγ剂量的60 Co -γ射线是较为适宜的唐菖蒲育种的照射剂量     

武汉市某医院~(60)Coγ-线事故性受照人员的体细胞染色体研究

在~(60)Coγ-线事故后1—3年,对事故中13名受射人员(医务人员9名,肿瘤病员4名)进行了细胞遗传学研究。结果表明,尽管相隔1—3年,淋巴细胞中的染色体畸变仍不失为一个灵敏而可靠的指标。受检医务人员的大多数均可由染色体畸变察觉其放射损伤,即便剂量低至5拉德也不例外。至于肿瘤病员,畸变率更高,除双着丝粒体外,还可见到3着丝粒体、4着丝粒体等多次击中畸变。     

~(60)钴γ-线离体照射人淋巴细胞诱发的染色体畸变:剂量-效应关系及其与 X-线的比较研究

为了把外周血淋巴细胞中所观察到的染色体畸变量用来估算活体照射的剂量,需要确定离体照射血样本的剂量-效应曲线。继X-线离体照射的刻度实验后,我们又研究了~(60)钴γ-线诱发染色体畸变的剂量-效应曲线,并且比较了这两种辐射的效应,所得的结论如下:1.根据人淋巴细胞的染色体畸变进行生物剂量测定,只有在标准条件下确定的离体剂量-效应曲线才能得出有意义的结果,也就是说,应尽可能地与事故照射时所出现的条件相同。我们的研究表明,细胞遗传学的剂量测定应在37℃照射未受PHA~**刺激的全血,培养的时间应少于54小时。当比较各实验室符合上述条件的剂量-效应曲线时,显然有差异。因此,我们提议在细胞遗传学技术“标准化”之前,各实验室应建立自己的刻度曲线。2.按照世界卫生组织的标准,在分析剂量-效应关系时,以最小二乘方对实验资料作泊森方差和加权回归分析,拟以恰当的模式。如X-线一样,~(60)钴γ-线诱发的双着丝粒体和着丝粒环资料最适于二次多项式,a=0(回归线通过原点),分别为Y_(γ-线)=(0.59±0.94)×10~(-4)D+(4.77±0.40)×10~(-6)D~2和Y_(x-线)=(0.51±0.21)×10~(-3)D+(5.02±0.77)×10~(-6)D~2。这一方程的物理含义是,一些互换畸变由一次击中所产生,而另一些则是由二个分开的击中相互作用所致。当把两种辐射的系数b 和c 作比较时,主要差别在于导致不对称互换畸变的b 项。根据该指数方程.,畸变量的直线成分(即由一击损伤所致)与剂量率无关,而λ值(b/c)即为一击和二击事件的提供量相等时的剂量,此值分别为λ_(γ-线)=12拉德,而λ_(X-线)=100拉德。由此可以设想,在从事~(60)钴γ-线超暴光例子的生物剂量测定时,与X-线相比较,更应考虑到剂量率的问题。双着丝粒体和着丝粒环资料,同样也可拟以幂函数,此时,Y_(γ-线)=1.64×10~(-5)D~(1.79±0.11),而Y_(X-线)=6.50×10~(-5)D~(1.61±0.05)。然而应当指出,资料拟以二次多项式比幂函数更好些,当从畸变量外推至低剂量时尤其是这样。3.鉴于各种辐射诱发的畸变量彼此不一,所以从辐射防护出发,必须分别地确定剂量-效应曲线。这里的工作表明,~(60)钴γ-线诱发畸变的效能比X-线要低。~(60)钴γ-线相对于180kVX-线诱发互换畸变的RBE 不是一个单一值,其RBE 值变动在0.12和0.89之间。从RBE-剂量关系可以看出,在所用的剂量范围(24～488拉德)内,RBE 值随~(60)钴γ-线剂量的增加而上升,随后即趋向于饱和。     

~(60)Co-γ线照射复合热烧伤对染色体畸变的影响

将狗于1.0—5.0戈瑞~(60)Co-γ线照射和该剂量复合15％二度烧伤,单纯烧伤和对照组之间,放射加热复合烧伤和单纯照射组之间,离体照射和整体照射之间,染色体畸变无显著性差异。经回归分析表明,不仅配合的模式相同,而且同一指标的回归系数相当接近,狗复合15％二度烧伤对外周血淋巴细胞染色体畸变未产生影响。因此,染色体畸变分析有作为放射加热复合烧伤时“生物剂量仪”的可能性。     

^60Co—r射线辐射番茄种子对根尖细胞遗传学效应的影响

用６０Ｃｏ－ｒ射线辐射番茄干种子,水培法生根后,观察根尖细胞有丝分裂中出现的桥、断片（含落后）、粘连、微核等染色体畸变类型,辐射剂量在５—１０ｋｒａｄ范围内畸变率较低;在１０—２０ｋｒａｄ范围内畸变率最高,畸变类型最丰富,在此范围内随剂量增加,断片数量增多,桥的类型除单桥外还出现多桥且数量增多,在２０ｋｒａｄ以上范围的高辐射剂量对染色体破坏力力较大,不利于番茄育种和生长。经对照实验和统计分析可知,辐射剂量的增加对有丝分裂有抑制作用。     

14Me V快中子和~(60)Coγ线对人血细胞脱氧核糖核酸(DNA)合成的影响

应用人血在体外接受14MeV快中子和~(60)Coγ线照射后进行培养,以~3氢-胸腺嘧啶核苷(~8H-TdR)作参入实验以反映DNA合成。采用液体闪烁测量法和放射自显影法发现两种射线对DNA合成的影响呈一定的规律性,即随照射剂量的增加,合成率显著降低。经统计处理分别得到中子和γ线的照射剂量和~8H-TdR参入的放射性脉冲数(或标记百分数)的对数值两变量间的直线回归方程,在中子剂量100～400拉德的范围内,中子/γ的R.B.E.为1.45～1.98。     

Genetic damage induced by in vitro irradiation of human G0 lymphocytes with low-energy protons (28 keV/microm): HPRT mutations and chromosome aberrations

Cell survival, mutations and chromosomal effects were studied in primary human lymphocytes exposed in G0 phase to a proton beam with an incident energy of 0.88 MeV (incident LET of 28 keV/microm) in the dose range 0.125-2 Gy. The curves for survival and mutations at the hypoxanthine-guanine phosphoribosyl transferase locus were obtained by fitting the experimental data to linear and linear-quadratic equations, respectively. In the dose interval 0-1.5 Gy, the alpha parameters of the curves were 0.42/Gy and 3.6 x 10(-6) mutants/Gy, respectively. The mutation types at the HPRT locus were analyzed by multiplex-PCR in 94 irradiated and 41 nonirradiated clones derived from T lymphocytes from five healthy donors. All clones showed a normal multiplex-PCR pattern and were classified as point mutations. Chromosome aberration data were fitted as a linear function of dose (alpha = 0.62 aberrations per cell Gy(-1)). By irradiating G0 lymphocytes from a single subject with 28 keV/microm protons and gamma rays, an RBE of 6.07 was obtained for chromosome aberrations. An overinvolvement of chromosome 9 relative to chromosome 7 was found in chromosome breaks after chromosome painting analysis.     

Radiobiological effects of a low-energy ion beam on wheat

The radiobiological effects of a low-energy nitrogen ion (N⁺) beam on wheat were studied, particularly with regard to the induction of chromosome aberrations. The results demonstrated that the three test varieties showed different sensitivities to ion implantation, and a higher dose of ion implantation had a marked effect on the germination and survival rate of the seeds exposed. The germination rate and survival rate curve basically followed a similar trend in the same variety. Cytological analysis indicated that ion beams were effective in producing chromosome aberrations. The frequencies of mitotic or meiotic cells with chromosome aberrations increased linearly with increasing doses. The aberration types included, for example, acentric fragments, chromosome deletions, lagging chromosomes, chromosome bridges and micronuclei. In the root tip cells, aberrations chiefly consisted of acentric fragments and deletions. Chromosome bridges and lagging chromosomes were the main aberration phenomena observed in the pollen mother cells. The highest frequencies of root tip cells and pollen mother cells with chromosome aberrations were 15.2% and 39.8%, respectively. Changes in morphology and mutant were also observed in the plants derived from exposed seeds. Received: 10 April 2000 / Accepted: 10 October 2000     

Chromosome aberration frequencies produced by a 70-MeV proton beam

The effectiveness of a 70-MeV proton beam in the induction of chromosome aberrations was studied. We employed peripheral lymphocytes and analyzed the frequencies of dicentrics and rings after irradiation at doses ranging from 0.1 to 8.0 Gy at various depths within a Lucite phantom. The frequency of chromosome aberrations after irradiation with an unmodulated proton beam at 5 mm showed a dose-response relationship similar to that of 60Co gamma rays. However, irradiation at greater depths with the spread-out Bragg peak induced higher aberration frequencies at doses lower than those with gamma rays. Furthermore, the distribution curve of chromosome aberration frequencies as a function of depth was found to be slightly different from the physically measured depth-dose curve. With the spread-out Bragg peak the biological effects were more marked at greater depths, resulting in a distribution of relative biological effectiveness values. The results obtained from chromosome aberration analysis may not be related directly to those for the relationship between dose and cell killing. Slight differences in values for relative biological effectiveness due to the change of dose and site of proton beam irradiation may not be important for practical proton beam therapy, but may be important in the prevention of late radiation injuries.     

2-[(Aminopropyl)amino] ethanethiol-mediated reductions in 60Co gamma-ray and fission-spectrum neutron-induced chromosome damage in V79 cells

The radioprotector 2-[aminopropyl)amino] ethanethiol (WR1065), which has been reported to reduce the cytotoxic and mutagenic effects of low LET radiation, was investigated for its ability to protect against low LET (60Co gamma ray) and high LET (fission-spectrum neutron)-induced chromosome damage in V79 cells. Cells were irradiated in G2 phase in the presence or absence of 4 mM WR1065 and were harvested and analyzed 2 h later for chromatid-type aberrations. Irradiation of G2-phase V79 cells in the presence of WR1065 resulted in a 30 to 50% reduction in the frequency of gamma-ray and neutron-induced chromatid-type breaks and exchanges. The effects were found only after exposures of greater than 200 cGy gamma-ray or 50 cGy neutron irradiation. The radioprotector was effective at reducing neutron-induced aberrations after exposures at dose rates of both 10 and 43 cGy/min. Thus the radioprotector WR1065 is an effective anti-clastogenic agent in V79 cells, protecting against both 60Co gamma-ray and fission-spectrum neutron-induced aberrations, when present during irradiation.     

Evaluation of the effect of 90Sr beta-radiation on human blood cells by chromosome aberration and single cell gel electrophoresis (comet assay) analysis

Among various environmental genotoxins, ionizing radiation has received special attention because of its mutagenic, carcinogenic and teratogenic potential. In this context and considering the scarcity of literature data, the objective of the present study was to evaluate the effect of 90Sr beta-radiation on human cells. Blood cells from five healthy donors were irradiated in vitro with doses of 0.2-5.0Gy from a 90Sr source (0.2Gy/min) and processed for chromosome aberration analysis and for comet assay. The cytogenetic results showed that the most frequently found aberration types were acentric fragments, double minutes and dicentrics. The alpha and beta coefficients of the linear-quadratic model, that best fitted the data obtained, showed that 90Sr beta-radiation was less efficient in inducing chromosome aberrations than other types of low linear energy transfer (LET) radiation such as 3H beta-particles, 60Co gamma-rays, 137Cs and 192Ir and X-rays. Apparently, 90Sr beta-radiation in the dose range investigated had no effect on the modal chromosome number of irradiated cells or on cell cycle kinetics. Concerning the comet assay, there was an increase in DNA migration as a function of radiation dose as evaluated by an image analysis system (tail moment) or by visual classification (DNA damage). The dose-response relation adequately fitted the non-linear regression model. In contrast to the cytogenetic data, 90Sr beta-radiation induced more DNA damage than 60Co gamma-radiation when the material was analyzed immediately after exposures. A possible influence of selective death of cells damaged by radiation was suggested.     

Radiation-induced chromosomal aberrations in the bone marrow of mice exposed to various doses of gamma radiation

The occurrence of chromosomal aberrations was studied at 1–14 days post-exposure in female BALB/c mice exposed to various doses of gamma radiation. The frequency of abnormal cells, chromatid and chromosome breaks, dicentrics, centric rings, acentric fragments and total aberrations increased with exposure dose, and it was highest at 7 Gy. A peak was recorded on day 1 post-exposure with a gradual decline thereafter. The chromosomal aberration yield reached a nadir on day 14 post-irradiation, without restoration to the control level. The best fit for the present data was by a linear-quadratic relationship between dose of radiation and the frequency of chromosomal aberrations.     

Studies on radiation-induced chromosome aberrations in mouse spermatocytes. II. Dose-response relationships of chromosome aberrations induced at zygotene stage in mouse primary spermatocytes following fast neutron- and 60Co gamma-irradiations

The chromosome aberrations induced at zygotene stage in mouse spermatocytes following exposures to fast neutrons and 60Co gamma-rays were examined at diakinesis-metaphase I. The dose-response relationships were well fitted to linear equation for deletion-type aberrations and to linear-quadratic equation for exchange-type aberrations in 60Co gamma-irradiation group. In fast neutron-irradiation group, the dose-response relationships were well fitted to linear equations for deletion- and exchange-type aberrations. The rate of deletion-type aberrations was remarkably high for fast neutrons, about 6 times higher than that after 60Co gamma-irradiation. The main types of chromosome aberrations observed were iso-chromatid breaks or fragments and chromatid exchanges in both irradiation groups as well as X-irradiation. These results indicate that there is a possibility that two double-strand breaks are induced simultaneously at iso-locus position in sister chromatids by a single track of radiations. Production of such single-track-induced two double-strand breaks in iso-chromatids may be very frequently expressed as iso-chromatid-type deletions in the high LET fast neutron-irradiation group. On the contrary, in the low LET 60Co gamma- or X-irradiation group, the above-mentioned mechanism may not be so effective for contribution to chromosome aberration induction in mouse spermatocytes. This mechanism was discussed in detail.     

Chromosomal analysis in mouse eggs fertilized in vitro with sperm exposed to ultraviolet light (UV) and methyl and ethyl methanesulfonate (MMS and EMS)

Chromosome aberrations were analyzed at the first-cleavage metaphase of mouse eggs fertilized in vitro with sperm exposed to ultraviolet light (UV) as well as to methyl and ethyl methanesulfonate (MMS and EMS). The frequencies of chromosome aberrations markedly increased with dose of UV as well as with concentration of MMS and EMS. In the UV-irradiation group, the frequency of chromosome-type aberrations was much higher than that of chromatid-type aberrations. About 90% of chromosome aberrations observed in the eggs following MMS and EMS treatment to sperm were chromosome type in which the frequency of chromosome fragments was the highest. The effects of UV on the induction of chromosome aberrations were clearly potentiated by post-treatment incubation of fertilized eggs in the presence of Ara-C or caffeine, but the effects of MMS and EMS were not pronounced by post-treatment of Ara-C or caffeine. The results indicate a possibility that UV damage induced in mouse sperm DNA is reparable in the eggs during the period between the entry of sperm into the egg cytoplasm and the first-cleavage metaphase.     

60Coγ射线辐照花魔芋球茎的早期诱变效应研究

本试验开展了花魔芋早期诱变效应研究。通过^60Coγ射线辐照后的植株苗期发育观察和根尖细胞学检测分析,结果表明魔芋辐射诱变效应显著：辐照诱发核畸变和染色体畸变,且变异频率与剂量呈二次曲线关系;低剂量时对细胞分裂有刺激作用;辐照抑制芽体发育、苗期生长,抑制效应随剂量增加而加大,直至产生致死作用。依据花魔芋的辐射敏感性,建立了魔芋辐照诱变体系,以催芽球茎为诱变材料,诱变剂量范围为0Gy～50Gy,剂量率为1Gy／min,中等适宜剂量为7Gy～10Gy,致死剂量50Gy。     

Unstable chromosome aberrations in peripheral blood lymphocytes from patients with cervical uterine cancer following radiotherapy.

Scoring of unstable chromosomes aberrations (dicentrics, rings and fragments) in circulating lymphocytes is the most extensively studied biologic system for estimating individual exposure to ionizing radiation. In this work, blood samples from 5 patients, with cervical uterine cancer, were analyzed by conventional cytogenetic in order to correlate the frequency of chromosome aberrations in lymphocytes with the dose absorbed by the patient, as a result of radiotherapy with 60Co gamma. The samples were collected in three phases of the treatment: before irradiation, 24 hr after receiving 0.08 Gy and 1.8 Gy, respectively. On the basis of the frequencies of unstable aberrations observed, a good agreement was obtained between doses estimated by calibration curve and the doses previously planned to radiotherapy. This report discusses the methodology employed as an important tool for dose assessment as a result of partial-body exposure to ionizing radiation.