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。     

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。     

染色体畸形变与膀胱癌发生发展的相关性研究

目的：通过荧光原位杂交技术（FISH）结合病理分级,探讨染色体畸形变与膀胱癌发生和发展的关系。方法：采用3、7、9、17号染色体着丝粒探针和9P16区带探针对105例膀胱癌复发患者尿液脱落细胞进行荧光原位杂交．观察膀胱癌复发患者中3、7、9、17号染色体的畸形变情况并分析其与患者临床和病理特征之间的关系。结果：105例膀胱癌复发患者中,3、7、9和17号染色体的非整数倍突变率分别是21．9％、29．5％、12．4％、和36．2％,与患者的性别、年龄无显著相关性（P〉0．05）。仅7号染色体畸变与膀胱癌的病理分级具有显著相关性[（P〈0．05）。结论：7号染色体畸形变与复发膀胱癌的病理分级显著相关。     

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。     

X染色体的DNA序列结构不同于6、7、8、10、11、12号染色体

雌性哺乳动物X染色体上的大部分基因均因X染色体失活作用而失去表达能力 ,X染色体长臂表现失活更明显。虽然对X染色体失活的许多方面都有所了解 ,但是仍然不清楚失活信号沿着X染色体全长扩散的机制。为了了解X染色体是否有不同于其他染色体的基因组学特征 ,这些特征是否关系到X染色体的失活扩散和维持 ,分析 6、7、8、1 0、1 1、1 2号染色体和X染色体DNA序列 7碱基 (7nt)组合水平的结构是否显示差异。从NCBI基因库(http :∥www .ncbi.nlm .nih .gov genome guide)下载 7条染色体长臂各 6 0Mb区域。将这 6 0Mb区域分为 0 5Mb (或 5 0kb)一段 ,对每一段DNA做 7nt字符串组合分析 ,如 1～ 7,2～ 8,3～ 9…… ,记录每种 7nt字符串的频率 ,A、C、G和T4个硷基的 7nt字符串共有 4 7=1 6 384种组合。根据数字差异显示的结果 (http :∥www .ncbi.nlm .nih .gov genome guide) ,选择在扁桃腺生发中心B细胞中高表达的基因 70个 ,用以计算所有内含子 (有义链 )的 7nt频率值。每个内含子被记录为一组 7nt频率值 ,求和相同基因中的所有内含子相同 7nt字符串的频率值 ,再用该和乘以该基因的表达频率得该基因 7nt字符串的频率值 ,求和 70个基因的 7nt字符串的频率值称做intron 7nt,该值试图模拟细胞中RNA小片段的总和。     

APM诱导蒜分生组织细胞染色体结构变异与蛋白质组变化(简报)(英文)

当蒜根尖分生组织细胞在4umol／L、6umol／L、8umol／L、10umol／L微管解聚型除草剂APM处理16h后,多极分裂细胞、凝集染色体、桥一断片及微核细胞可明显被观察到．其中多极分裂细胞可分别达10．7％、10．7％、11．1％和10．0％;凝集染色体为5．5％、5．9％、7．1％和9．1％：出现桥和断片的频率为1．9％、1．8％、2．7％和5．5％;出现微核细胞的频率分别为2．8％、8．7％、12．5％和16．3％。分生组织内蛋白质组也产生了明显变化,有5个分子量和等电点分别为66kD／p16．3、48kD／p16．6、48kD／p16．9、16kD／p15．6、18kD／p15．2的蛋白质在8umol／LAPM处理的分生组织中被合成．通过MALDI—TOF—MS分析和NCBI 20070528数据库查询．其中3个新合成的蛋白质被确认,它们是S-腺苷甲硫氨酸合成酶、抗坏血酸过氧化物酶和磷酸甘油酸激酶C。染色体结构变异和蛋白质组变化被认为与APM的处理有关的．     

三色荧光原位杂交技术（Triple—FISH）检测男性不育患者精子染色体的非整倍体性

目的：研究精子非整倍体染色体与男性不育之间的关系。方法：用荧光原位杂交（FISH）技术,对12个不育患精子的染色体进行了研究,其中,10例少,弱,畸精症患为A组,2例正常或接近正常的样品为B组,另有2例正常健康献精为对照组,原位杂交采用染色体XY和18号探针,每个个体记数1000个精子,结果：杂交总有效率为98％,在B组男性不育XY和18号的二体频率为0．30％和0．30％,与对照组相比（0．15％,0％）无显差别,XY和18号失体的精子为0．15％和0％,与对照组（0％,0．15％）也无显差别,而A组的XY和18号染色体二体率为1．13％和0．96％,失体为1．13％和1．6％,与前两组相比,差异有显性,估算总的非整倍体率：A组为42．44％,B组为6．05％,对照组为2．59％,前与后两组相比,差异有显性,结论：不育患精子的染色体具有显的非整倍体性。     

减毒麻疹活疫苗对小鼠的细胞遗传学效应

本文以C57BL/6J小鼠为材料,以骨髓细胞微核、染色体畸变和生殖细胞微核、染色体畸变为指标,对国产减毒麻疹活疫苗的遗传安全性进行评价。结果表明,麻疹疫苗可引起小鼠骨髓微核细胞率、染色体畸变率以及精细胞微核细胞率明显升高,与接种剂量和接种后的时间有关;生殖细胞染色体畸变和对照比无显著性差异。     

转基因抗矮花叶玉米对大白鼠骨髓细胞遗传毒性的影响

以SD大鼠为研究对象,研究了转基因抗矮花叶玉米和常规玉米对大白鼠骨髓细胞微核率与染色体畸变率的影响,以观察该转基因玉米对大白鼠可能产生的遗传毒理效应。实验结果表明：饲喂30%和50%转基因玉米日粮组的大白鼠骨髓细胞微核率和染色体畸变率与饲喂常规玉米相比均没有显著差异,而与阳性对照组之间存在极显著差异,这说明转基因玉米与常规玉米对大白鼠骨髓细胞均无遗传毒性。     

超低能离子注入作物育种的一种重要机制

本文通过超低能（１１０ｋｅＶ）离子注入和同步辐射碳光辐照两种手段处理了小麦种子,经萌发在其根尖细胞中均观察到了多种类型的染色体时变,而且同对照相比,均有明显的微核率与染色体总畸变率。根据理论分析和一些有关的实验证据,超低能离子注入小麦种子,因离子本身射程非常短（＜１μｍ）,不可能直接损伤麦皮下面的胚细胞,而由注入离子在作物种子内产生的各种特征Ｘ－射线,只要剂量足够,却能达到较深的部位,通过它们的间接作用就会损伤胚细胞造成生物学效应。因此,赵低能离子注入作物种子激发产生的特征Ｘ－射线是其诱变育种的一种重要机制．     

X chromosome inactivation and micronuclei in normal and Turner individuals

Studies on aneuploidy have shown that the X is the most frequently lost chromosome in females, and that the number of X chromosome-positive micronuclei increases with age in women. Recently, we showed that the inactive X chromosome is incorporated preferentially in micronuclei. The objectives of the current study were, firstly, to determine the incidence of X chromosome incorporation into micronuclei in males and, secondly, to determine the incidence of X chromosome incorporation into micronuclei of females with Turner syndrome. Blood samples were obtained from 18 male newborns and 35 normal adult males ranging in age from 22 to 79 years and from seven women with non-mosaic Turner syndrome aged 11–39 years. Isolated lymphocytes were cultured in the presence of cytochalasin B and 2000 binucleated cells per subject were scored for micronuclei. Cells were then hybridized with the biotinylated X centromere-specific probe, pBamX7, and visualized with fluorescein-conjugated avidin. All micronucleated cells were relocated and evaluated for the presence or absence of the X chromosome. Of the 335 micronuclei observed, 6.6% (22/335) contained an X chromosome. Analysis of variance shows a statistically significant increase, for both males and Turner females, in the number of X chromosome-positive micronuclei with age (P < 0.001). These data also show that the X chromosome is included in micronuclei from males more often than would be expected by chance (P < 0.005; χ² analysis, 15 df). Here we show that there is a tenfold difference in the frequency of X chromosome-positive micronuclei in 46,XX females compared to 46,XY males and 45,X females, providing further support to our previous finding that the X chromosome in micronuclei is the inactive chromosome. Received: 29 April 1997 / Accepted: 9 May 1997     

Chromosome nondisjunction and loss induced by protons and X rays in primary human fibroblasts: role of centromeres in aneuploidy

To study the origin of micronuclei induced in human primary fibroblasts by low-energy protons (7.7 and 28.5 keV/microm) and X rays, we have developed a combined antikinetochore-antibody (CREST) and FISH staining with pancentromeric probes. This technique allowed us to analyze the integrity of the kinetochore and centromeric DNA structures and to assess their role in induced aneuploidy. The effect of LET on radiation-induced chromosome nondisjunction was studied in binucleated cells with centromeric-specific DNA probes for chromosomes 7 and 11. Our results indicate that, though more than 90% of radiation-induced micronuclei were CREST(-)/FISH(-), 28.5 keV/microm protons and X rays were also able to induce statistically significant increases in the number of micronuclei that were CREST(-)/FISH(+) and CREST(+)/FISH(+), respectively. One interpretation of these results could be that the protons induced chromosome loss by kinetochore detachment or by breakage in the centromeric DNA region, whereas X rays induced aneuploidy through a non-DNA damage mechanism. Nondisjunction appears to be a far more important mechanism leading to radiation-induced aneuploidy. Irrespective of the higher frequency of micronuclei induced by 28.5 keV/microm protons, the frequency of chromosome loss was markedly higher for X rays than for 28.5 keV/microm protons, strengthening the hypothesis that non-DNA targets, such as components of the mitotic spindle apparatus, may be involved in aberrations in chromosome segregation after X irradiation.     

Age-dependent inclusion of sex chromosomes in lymphocyte micronuclei of man.

Two-color centromeric FISH was used to study the inclusion of the X and Y chromosomes in micronuclei of cultured lymphocytes from 10 men representing two age groups (21-29 years and 51-55 years). In addition, pancentromeric FISH was separately performed to identify any human chromosomes in micronuclei. One hundred micronuclei per probe were examined from each donor. A higher mean frequency of Y-positive micronuclei was observed in the older men than in the younger men. In both age groups, the X chromosome was micronucleated clearly more often than expected by chance, and the Y chromosome was overrepresented in micronuclei among the older men but not among the younger men. In lymphocytes of four women, X-positive micronuclei were more frequent than they were in men, even after the fact that women have two X chromosomes was taken into account. Similar results were obtained in first-division lymphocytes identified by cytochalasin-B-induced cytokinesis block. In comparison with normal cells, these binucleate cells showed a higher frequency (per 1,000 nuclei) of X-positive micronuclei (in the older men) but a lower frequency of micronuclei harboring autosomes or acentric fragments. In conclusion, the results show that both the X chromosome and the Y chromosome are preferentially micronucleated in male lymphocytes, the Y chromosome only in older subjects. Although the X chromosome has a general tendency to be included in micronuclei, it is micronucleated much more often in women than in men, which is probably the main reason for the high micronucleus frequency in women that has been documented in many previous studies.     

Activation status of the X chromosome in human micronucleated lymphocytes

The frequency of X chromosome aneuploidy in human female peripheral blood lymphocytes has been reported by several investigators to be significantly higher than expected based upon chance alone. Studies in our laboratory showed that 72% of the micronuclei in the peripheral blood of human females contained the X chromosome. Such a high frequency of X chromosome loss suggests that some unique mechanism may be responsible for this phenomenon. The present study was carried out to test the hypothesis that the lost or micronucleated chromsome is the inactive and not the active X. Blood samples were obtained from two unrelated females, 36 and 33 years of age, each with a different X; 9 reciprocal translocation. In each, the normal X chromosome is inactive and the translocated X is active. Isolated lymphocytes were cultured according to standard techniques and blocked with cytochalasin B. Using a modified micronucleus assay, we scored 10,000 binucleated cells from the 36 year old, while 9,500 binucleated cells were scored from the 33 year old. The slides were first labeled and the kinetochore status of each micronucleus was determined. This was followed by simultaneous hybridization with a 2.0 kilobase centromeric X chromosome-specific probe and a chromosome 9 specific whole chromosome painting probe. All micronucleated cells were relocated and scored for their probe status. A total of 217 micronuclei were scored from the two subjects, of which 96 (44.2%) contained the X chromosome. Of these 96 micronuclei, 80 (83.3%) contained the inactive X, based on the absence of chromosome 9 material in the micronucleus. These results support our hypothesis that the inactive X chromosome is preferentially included in the micronuclei, and suggest that the X chromosome hypoploidy observed at metaphase in aging women is a related phenomenon. Received: 5 May 1995 / Revised: 15 July 1995     

SYNTHETIC CAPACITIES OF CHROMOSOME FRAGMENTS CORRELATED WITH THEIR ABILITY TO MAINTAIN NUCLEOLAR MATERIAL

Onion (Allium cepa) and bean (Vicia faba) root tip cells containing many micronuclei, derived from x-ray-induced chromosome fragments, were exposed to H³-thymidine and H³-cytidine to determine the ability of such fragments to undergo DNA and RNA synthesis. Only a few micronuclei in onion and many in bean roots synthesize nucleic acid simultaneously with their main nuclei. A few micronuclei labeled with H³-thymidine undergo mitotic chromosome condensation along with the main nuclei, while the unlabeled ones never do so. The onset of nucleic acid synthesis as well as mitosis in micronuclei appears to be under generalized cellular control. Although all chromosomes and chromosome fragments at telophase give a positive reaction for a silver stainable nucleolar fraction, in the subsequent interphase only some micronuclei, derived from such chromosome fragments, are found to maintain nucleoli; others lose them with time. Those micronuclei which maintain nucleoli, perhaps due to the presence of specific chromosomal regions, are also active in DNA and RNA synthesis. These results are compatible with the concept that nucleoli and associated chromosome regions play an important role in the primary biosynthetic processes of the cell.     

Synaptonemal complex analysis of X-7 translocations in male mice: R2 and R6 quadrivalents

Synaptonemal complexes of surface-spread spermatocytes of mice heterozygous for reciprocal translocations R2 or R6 between the X-chromosome and chromosome 7 were examined by light and electron microscopy (EM). Measurements of the lengths of all chromosome axes involved in the translocation configurations and of the extent of synapsis were used to calculate the position of the break points of the two translocations. The breaks for R2 were determined to be at 62% of the 7 as measured from the centromere, and at 27% of the X. Quadrivalents were formed almost exclusively. The break points for R6 were calculated to be at 30% of the 7 as measured from the centromere, and at 75% of the X. Although in R6 the break in the X lies within the potential pairing region of the sex chromosomes, univalent Ys were rarely observed (6%). The EM sample of 76 nuclei contained: 42% quadrivalents, 52% heteromorphic bivalents, 4% trivalent plus Y univalent, and 2% X7-7 bivalent plus two univalents (7X and Y). Nonhomologous synapsis occurred in the quadrivalents of both R2 and R6. In R6 nonhomologous synapsis of the X portion of the 7X with the 7 involved up to 14% of the length of the 7. Methods are discussed for determining the position of the break points in the presence of nonhomologous synapsis. It is proposed that the high percentage of bivalents is due to premature desynapsis of the 7X from the 7 and that the X portion of the 7X axis confers its property of premature desynapsis on that portion of the 7 to which it is attached.     

The X chromosome frequently lags behind in female lymphocyte anaphase

Pancentromeric FISH and X-chromosome painting were used to characterize anaphase aberrations in 2,048 cultured lymphocytes from a healthy 62-year-old woman. Of 163 aberrant anaphases, 66.9% contained either chromosomes or their fragments that lagged behind. Characterization of 200 laggards showed that 49% were autosomes, 33. 5% were autosomal fragments, and 17.5% were X chromosomes. The X chromosome represented one-fourth of all lagging chromosomes and was involved much more often than would be expected by chance (1/23). Labeling of the late-replicating inactive X chromosome with 5-bromo-2'-deoxyuridine revealed that both X homologues contributed equally to the laggards. Among 200 micronuclei examined from interphase cells, the proportion of the X chromosome (31%) and autosomal fragments (50%) was higher than among anaphase laggards, whereas autosomes were involved less often (19%). These findings may reflect either selection or the fact that lagging autosomes, which were more proximal to the poles than were lagging X chromosomes, were more frequently included within the main nucleus. Our results suggest that the well-known high micronucleation and loss of the X chromosome in women's lymphocytes is the result of frequent distal lagging behind in anaphase and effective micronucleation of this chromosome. This lagging appears to affect the inactive and active X chromosomes equally.     

Damage to lymphocytes by X-ray and bleomycin measured with the cytokinesis-block micronucleus technique.

Chromosome damage induced by X-irradiation or bleomycin was measured using the cytokinesis-block micronucleus assay in the peripheral blood lymphocytes of 6 newborn, 8 young and 10 elderly individuals. An increase in the frequency of spontaneous micronuclei with age was observed. There was no difference in the X-irradiation-induced micronucleus frequency between the 3 groups. There was a significant increase with age in the number of micronuclei induced by bleomycin. Kinetochore-labelling studies revealed that the percentage of kinetochore-positive induced micronuclei was higher for bleomycin (36.2-43.3%) than for X-irradiation (17.1-19.7%). The age-related increase in frequency of spontaneous or bleomycin-induced micronuclei was due to increases in both kinetochore-positive and kinetochore-negative micronuclei. The frequency of kinetochore-positive or -negative micronuclei induced by X-irradiation was not different between the 3 age groups. These results suggest that bleomycin is more potent in inducing whole-chromosome loss than X-rays, and that lymphocytes from aged individuals are more sensitive to bleomycin in terms of both chromosome breakage and whole chromosome loss.     

The human leulocyte test system. VII. Further investigations concerning micronucleus-derived premature chromosome condensation.

Premature chromosome condensation (PCC) from X-ray induced micronuclei shows a dose-effect relationship in human leukocytes in vitro. Preparations at different culture times without colcemide treatment reveal complex variations of the frequencies of micronuclei and PCC correlated with the fixation time. The positions of PCC patches in the metaphase plate and the frequencies of different PCC types (S and G2) ar independent on the X-ray dose. The latter indicates that the slowing down of the micronuclei in the cell cycle, which is the reason for the formation of PCC, may be an outcome rather of a regulatory phenomenon than of an unspecific physiological damage of the chromatin included in the micronuclei. This is especially evident from labeling experiments with tritiated thymidine, showing that the extent of asynchrony between main nuclei and micronuclei is independent on the X-ray dose. Labeling experiments with tritiated uridine reveal a X-ray dose dependent suppression of RNA synthesis in cells with main nuclei and micronuclei. THE S-phase nature of "pulverized" PCC patches could be verified by incorporation of tritiated thymidine in aound 50%. Staining of centromeric heterochromatin in micronuclei reveal a frequency of micronuclei with centromeric heterochromatin resembling the frequency of G2-phase PCC found in mitoses.     

石貂的染色体研究

本文对分布在我国的石貂北方亚种染色体进行了较详细的研究。结果表明２ｎ＝３８,核型为１４（Ｍ）＋４（ＳＭ）＋１８（ＳＴ）,ＸＹ（Ｍ,Ａ）。Ｃ－带显示该亚种的一些染色体着丝粒区域结构异染色质弱化或消失。Ｎｏ,９染色体的短臂完全异染色质化;Ｘ染色体长臂丰出现插入杂色质带;Ｙ为完全结构异染色质组成。