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Volume 47 (2006)
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Volume 47, Issue 3+4
Displaying 1-9 of 9 articles from this issue
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Regular Paper
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Ryouhei YOSHIHARA, Chiyoko NAKANE, Koichi TAKIMOTO2006 Volume 47 Issue 3+4 Pages 223-228
Published: 2006
Released on J-STAGE: November 25, 2006
Advance online publication: September 06, 2006JOURNAL FREE ACCESSA system was developed for the detection and analysis of mutations occurring on chromosomal DNA in plants. The plasmid pML4, carrying the Escherichia coli rpsL gene, a target gene for mutagenesis, was inserted into a shuttle vector, pCGN5138, to construct a plasmid which could be used for the transformation of plants. pML4 sequences were introduced into Arabidopsis thaliana mediated by Agrobacterium. The pML4 DNA was rescued from transgenic Arabidopsis plants exposed to mutagens, and the plasmids were introduced into Escherichia coli DH10B to isolate mutant clones. In this system, any form of inactivation mutation in the rpsL gene can be positively selected since it makes the E. coli cells resistant to streptomycin. Here we report that the system could detect the mutagenic effect of ethylmethanesulfonate (EMS). Further characterization of the mutants revealed that G:C to A:T transitions predominated among the EMS-induced mutations. This assay system is useful for the detection and analysis of mutations arising on chromosomal DNA in plants, and should be useful for evaluating analysis of the effects of environmental mutagens.
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Ewa M. NOWOSIELSKA, Jolanta WREMBEL-WARGOCKA, Aneta CHEDA, Emil LISIAK ...2006 Volume 47 Issue 3+4 Pages 229-236
Published: 2006
Released on J-STAGE: November 25, 2006
Advance online publication: August 25, 2006JOURNAL FREE ACCESSWe showed in our previous report that a single exposure of mice to 0.1 or 0.2 Gy X-rays led to the significant inhibition of the development of artificial tumor metastases in the lungs and that the effect was related to the enhanced activity of natural killer cells. In the present study, a possible involvement of cytotoxic macrophages in the anti-metastatic effect of the low-level X-ray exposures was investigated. We now demonstrate that irradiation of mice with either of the two low doses of X-rays significantly stimulates the macrophage-mediated cytolysis of the susceptible tumor targets and that the effect coincides with the enhanced production of nitric oxide in the collected effector cells. We also show that suppression of the in vivo function of macrophages by carrageenan eliminates the inhibitory effect of the two low doses of X-rays on the development of pulmonary tumor colonies as well as significantly suppresses the macrophage-mediated cytotoxicity and nitric oxide production. Finally, aminoguanidine added to the culture medium of the assayed macrophages not only shuts down the nitric oxide synthesis in these cells but also significantly suppresses their cytolytic activity. Overall, the obtained results indicate that inhibition of the tumor metastases by a single exposure of mice to 0.1 or 0.2 Gy X-rays results, to a large extent, from the radiation-induced stimulation of the cytocidal activity of macrophages which secrete enhanced amounts of nitric oxide.
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Takehiko KAKIZAKI, Nobuyuki HAMADA, Seiichi WADA, Tomoo FUNAYAMA, Tets ...2006 Volume 47 Issue 3+4 Pages 237-243
Published: 2006
Released on J-STAGE: November 25, 2006
Advance online publication: September 06, 2006JOURNAL FREE ACCESSWe have examined in vitro radiosensitivities and radioresponses to 60Co γ-rays irradiation in feline T-lymphocyte cell lines, FeT-J and FL-4. There seemed to be no significant difference in clonogenic survival between the two lines. The mean lethal dose for both was both 1.9 Gy, and surviving fraction at 2 Gy was 0.30 and 0.48 for FeT-J and FL-4 cells, respectively. However, TUNEL assay indicated much higher degrees of apoptosis induction in FeT-J cells (>40%) than in FL-4 cells (<10%) at 4 days after 15 Gy irradiation. Microscopic examination revealed a larger population of multi-nucleate cells in FL-4 cells (60.3%) than in FeT-J cells (16.0%) at 4 days after 15 Gy irradiation, suggesting that a larger ratio of mitotic catastrophe occurred in FL-4 cells. These results suggest that FeT-J is more likely to be induced into apoptosis and FL-4 is more likely to fall into mitotic catastrophe, and eventually necrosis; both of them showed a similar surviving fraction against γ-rays. The results also indicate that FL-4 cells follow a process other than apoptosis to cell death, suggesting the presence of a regulatory mechanism that may control the relationship between mitotic catastrophe and apoptosis in feline T-lymphocytes.
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Yasushi KATAOKA, Vytautas P. BINDOKAS, Ryan C. DUGGAN, Jeffrey S. MURL ...2006 Volume 47 Issue 3+4 Pages 245-257
Published: 2006
Released on J-STAGE: November 25, 2006
Advance online publication: September 06, 2006JOURNAL FREE ACCESS
Supplementary materialWe applied a flow cytometric method to quantify IR-induced histone H2AX phosphorylation at serine 139 (γH2AX) and compared those values to those obtained using a standard microscopy based foci counting method. After PFA fixation, methanol permeabilization was suitable for both FITC- or Alexa647-γH2AX. In contrast, Alexa647-γH2AX was not suitable for ethanol permeabilization. Antibody concentrations at 1-2 μg/ml yielded the highest γH2AX positive percentage for both antibodies. Without DAPI staining, γH2AX formation can be measured as a relative fold increase. Values determined by bivariant flow cytometric analysis and those obtained using microscopic foci formation exhibited a good quantitative correlation. Values obtained by both methods could vary according to the gating or threshold setting used. γH2AX positive cells increased as a function of radiation dose (2-16 Gy) followed by a dose-dependent decay. The free radical scavenger N-acetyl-L-cysteine (NAC), if administered at a concentration of 4 mM 30 min before IR, was effective in reducing IR-induced γH2AX formation in all phases of the cell cycle. We have developed a simplified and quantitative flow cytometry based method to measure IR-induced γH2AX in cells and demonstrated strong correlation to values obtained by a standard automated digital microscopic foci analysis along with NIH ImageJ custom macro software (Appendix).
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Eve KLISING-SIREUL, Odile RIGAUD, Katherine ORY, Nicolas UGOLIN, J&eac ...2006 Volume 47 Issue 3+4 Pages 259-272
Published: 2006
Released on J-STAGE: November 25, 2006
Advance online publication: September 15, 2006JOURNAL FREE ACCESSExperiments were designed to compare the transcriptional response to ionizing radiation (IR) of wild-type (WT) and ataxia telangiectasia (AT) cells. mRNA levels were assessed 2, 4 and 24 h after exposure to equitoxic doses using cDNA microarrays. Data reveal distinct patterns of gene expression between AT and WT cells since IR-responsive genes were mostly cell-type specific, this group representing 87 and 94% of the responding genes in WT and AT cells, respectively. In both cell lines, transcriptional alterations of genes associated with proliferation correlated with the observed cell cycle and growth data. Deregulated genes involved in apoptosis suggest that wild-type cells were more prone to cell death by apoptosis than AT cells. Furthermore, genes associated with the response to oxidative stress were particularly deregulated in wild-type cells whereas alterations of genes related to unexpected pathways including RNA processing, protein synthesis and lipid metabolism were specifically found in irradiated AT cells. These data suggest that under radiation conditions leading to a similar survival of WT and AT cells, the mechanisms triggered after radiation were mainly dependent on ATM status and thus on the intrinsic radiosensitivity.
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Li-Jun WEI, Qian YANG, Hong-Mei XIA, Yoshiya FURUSAWA, Shuang-Hong GUA ...2006 Volume 47 Issue 3+4 Pages 273-278
Published: 2006
Released on J-STAGE: November 25, 2006
Advance online publication: September 15, 2006JOURNAL FREE ACCESSTo analyze the biological effects of the space environment, we flew nine lines of rice seeds on the Chinese 20th recoverable satellite for a duration of 18 days. The same lines of seeds were also irradiated to low doses (2.0mGy) of Carbon, or Neon or Iron ions (with different LET value of 13.3 keV/μm, 31 keV/μm and 500 keV/μm respectively) at National Institute of Radiological Sciences in Chiba, Japan. The total number of mitotic cells and chromosomal aberrations were analyzed. The mitotic index (MI) and the frequency of chromosomal aberration were evaluated in order to compare the cytogenetic damages from spaceflight and from exposure to similar doses of charged particle on the ground. The results of the present study show that the space environment and heavy energy ion can alter cell growth, and induce various chromosome aberrations including micronuclei, chromosomal bridges, fragments and laggards. With all the lines combined, the frequency of chromosome aberrations and MI in seeds flown in space are the highest. The effectiveness of cytogenetic damage from spaceflight (SP) and the heavy ion irradiations is SP > Fe > Ne > C.
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Shahla MOHAMMADI, Mahnaz TAGHAVI-DEHAGHANI, Mohammad R. GHARAATI, Reza ...2006 Volume 47 Issue 3+4 Pages 279-285
Published: 2006
Released on J-STAGE: November 25, 2006
Advance online publication: September 21, 2006JOURNAL FREE ACCESSThe hot springs in certain areas of Ramsar contain 226Ra and 222Rn. The effects of natural radiation on the inhabitants of these areas and the inhabitant's radiosensitivity or adaptive responses were studied. One group of volunteers from areas with high natural background radiation and another group from areas with normal background radiation were chosen as the case and control group respectively. The frequency of micronuclei, apoptosis, and DNA damage in peripheral blood mononuclear cells were measured following γ irradiation (4 Gy). The incidence of micronuclei in the case group was significantly lower than that in the control group while their frequency of apoptosis was higher (P < 0.05). However, the rates of induced DNA damage and repair were significantly higher in the case group (P < 0.05). Smaller number of micronuclei and higher levels of apoptosis in the case group could be the result of higher resistance to radiation stress and a more rigorous checkpoint at cell division. However, regarding the alkaline labile sites, the individuals in the case group are more sensitive and susceptible to DNA damage. The results of micronuclei, apoptosis and repair studies suggest that an adaptive response might be induced in people residing in areas with high background radiation.
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Zhao-Wen ZONG, Tian-Min CHENG, Yong-Ping SU, Xin-Ze RAN, Nan LI, Guo-P ...2006 Volume 47 Issue 3+4 Pages 287-293
Published: 2006
Released on J-STAGE: November 25, 2006
Advance online publication: September 15, 2006JOURNAL FREE ACCESSOur previous study indicated that dermal multipotent cells (DMCs) could engraft into bone morrow (BM) of rats with sublethal irradiation and promote hematopoietic recovery after being transplanted systemically, but the mechanisms determining the recruitment of DMCs to the irradiation injured BM remain unclear. In the present study, we investigated the role of stromal cellderived factor-1 (SDF-1)/CXCR4 interaction in this process. Male DMCs were isolated and transplanted into female rats systemically, and by employing quantitative real-time TaqMan polymerase chain reaction for the sex-determining region of Y chromosome, it was found that the amount of DMCs in BM of rats with sublethal irradiation was about 3 times more than that of normal rats (P < 0.01). Incubation of DMCs with AMD3100 before transplantation, which specifically blocks binding of SDF-1 to its endogenous receptor CXCR4, diminished recruitment of DMCs to the injured BM by 57.2 ± 5.5% (P < 0.05). In addition, it was confirmed that the expression of SDF-1 in injured BM was up-regulated when compared with that in normal BM, and in vitro analysis revealed that BM extracts from irradiated rats had a strong chemotactic effect on DMCs, which decreased significantly when DMCs were pre-incubated with AMD3100 (P < 0.05). These data suggest that transplanted DMCs were recruited more frequently to irradiation-injured BM than normal BM and the interactions of SDF-1/CXCR4 played an important role in this process.
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Takako YASUDA, Kazuko AOKI, Atsuko MATSUMOTO, Kouichi MARUYAMA, Yasuko ...2006 Volume 47 Issue 3+4 Pages 295-303
Published: 2006
Released on J-STAGE: November 25, 2006
Advance online publication: September 21, 2006JOURNAL FREE ACCESSMedaka (Oryzias latipes) embryos at 25-26 and 28-30 stages were irradiated with a single acute dose of 10 Gy of X-ray, which is lower than the LD50 of the embryos. The effects on developing brains were examined under a stereomicroscope in living embryos until hatching. All the irradiated embryos survived; however, from 6 to 35 h after X-ray irradiation, massive clusters of optically opaque and round cells were observed either in the entire brain region (when irradiated at 25-26 stages) or mainly in the optic tectum (when irradiated at 28-30 stages). Histological examination and TUNEL showed that these cells are clusters of dead cells. These dead cell clusters disappeared thereafter, and the irradiated embryos continued to develop apparently normally. The grown irradiated embryos, however, had smaller brains and eyes than the nonirradiated control embryos. At hatching, the irradiated embryos exhibited histological abnormalities in the brain, particularly in the torus longitudinalis, and in the retina, although most of them hatched normally and survived. The results indicate that brain cell death and a reduced brain size can be observed in living irradiated embryos, and suggest that the medaka embryo is useful for screening the developmental neurotoxicity effects of various hazardous factors.
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