All issues
Volume 42 (2001)
- Issue 4 Pages 347-
- Issue 3 Pages 247-
- Issue 2 Pages 117-
- Issue 1 Pages 1-
- Issue SUPPL Pages S1-
Volume 42, Issue 3
Displaying 1-8 of 8 articles from this issue
- |<
- <
- 1
- >
- >|
Regular Papers
-
TAKESHI HIRANO, HIDEYASU HIRANO, RAIZO YAMAGUCHI, SHINYA ASAMI, YOSUKE ...Article type: Regular papers
2001 Volume 42 Issue 3 Pages 247-254
Published: 2001
Released on J-STAGE: December 04, 2001
JOURNAL FREE ACCESSThe base excision repair system for 8-hydroxyguanine (8-OH-Gua) is believed to play a role in the prevention of mutations, such as GC-to-TA transversion, which leads to cancer development. However, the exact repair mechanism is still unclear. In this study, we examine whether the repair activity level for 8-hydroxyguanine, one of the major forms of oxidative DNA damage, depends on the sequence of the substrate DNA. We prepared six different oligonucleotides containing 8-hydroxyguanine as substrates and reacted them with crude extracts from the livers and kidneys of 8-week-old Sprague-Dawley rats. As a result, up to a 10-fold difference in the repair activity levels was observed, depending on the substrates used. Based on this observation, we suggest that the repair systems may act with sequence specificity on the damaged DNA.View full abstractDownload PDF (239K) -
SUNG HO KIM, JONG HWAN LEE, HEON OH, SE RA KIM, CHA-SOO LEE, SUNG KEE ...Article type: Regular papers
2001 Volume 42 Issue 3 Pages 255-264
Published: 2001
Released on J-STAGE: December 04, 2001
JOURNAL FREE ACCESSIn order to evaluate the importance of gestational age and the dose-incidence relationship by gamma radiation, pregnant ICR mice at gestational days from 2.5 to 15.5 days post-coitus (p.c.) were exposed to a single dose of 2.0 Gy and also at day 11.5 after conception, which was the most sensitive stage for the induction of major congenital malformations. The animals were sacrificed on day 18 of gestation and the fetuses were examined for mortality, growth retardation, changes in head size and other morphological abnormalities. The only demonstrable effect of irradiation during the pre-implantation period was an increase in prenatal mortality. Resorptions were maximal on exposure at day 2.5 after conception. The pre-implantation irradiated embryos which survived did not show any major fetal abnormalities. A small head, growth retardation, a cleft palate, dilatation of the cerebral ventricle, a renal pelvis, and abnormalities of the extremities and tail after exposure were prominent during the organogenesis period, especially on day 11.5 of gestation. As for the dose-incidence relationship, the incidence of a small head, growth-retarded fetuses, a cleft palate, dilatation of cerebral ventricle and abnormalities of the extremities in live fetuses rose as the radiation dose increased. The result indicated that the late period of organogenesis in the development of the brain, skull and extremities of a mouse was a particularly sensitive phase. The threshold doses of radiation that induced a cleft palate and dilatation of the cerebral ventricle, and abnormal extremities were between 1.0 and 2.0 Gy, and between 0.5 and 1.0 Gy, respectively.View full abstractDownload PDF (46K) -
YEUNHWA GU, TAKEO HASEGAWA, YOUICHI YAMAMOTO, MICHIAKI KAI, TOMOKO KUS ...Article type: Regular papers
2001 Volume 42 Issue 3 Pages 265-272
Published: 2001
Released on J-STAGE: December 04, 2001
JOURNAL FREE ACCESSThe combined effects of X-rays and magnetic resonance imaging (MRI) on mouse embryos at an early stage of organogenesis were investigated. Pregnant ICR mice were irradiated on day 8 of gestation with X-rays at a dose of 1 Gy and/or MRI at 0.5 T for 1 hour. The mortality rates of the embryos or fetuses, the incidence of external malformations, the fetal body weight and the sex ratio were observed at day 18 of gestation. A significant increase in embryonic mortality was observed after exposure to either 1 Gy of X-radiation or 0.5 T MRI. However, the combined X-rays and MRI did not show a statistically significant increase in embryonic mortality compared with the control. External malformations, such as exencephaly, a cleft palate and anophthalmia, were observed in mice irradiated with X-rays and/or MRI. The incidence of each malformation in all treated groups increased with statistical significance compared with the control mice. The incidence in mice irradiated with both X-rays and MRI was lower than in mice irradiated with only X-rays. The combined effects of the combination of radiation and MRI on the external malformations might be antagonistic. There were no statistically significant differences in fetal death, fetal body weight and sex ratio among all experimental groups.View full abstractDownload PDF (40K) -
RYUJI OKAZAKI, AKIRA OOTSUYAMA, SOSHI UCHIDA, TOSHIYUKI NORIMURAArticle type: Regular papers
2001 Volume 42 Issue 3 Pages 273-283
Published: 2001
Released on J-STAGE: December 04, 2001
JOURNAL FREE ACCESSIn order to determine the effects of a 4.7 T static magnetic field (SMF) on fetal development in mice, we evaluated fetal teratogenesis and endochondral ossification following exposure in utero. Pregnant ICR mice were exposed to a 4.7 T SMF from day 7.5 to 9.5 of gestation in a whole-body dose, and sacrificed on day 18.5 of gestation. We examined the incidence of prenatal death, external malformations and fetal skeletal malformations. There were no significant differences observed in the incidence of prenatal death and/or malformations between SMF-exposed mice and control mice. Further, we evaluated the immunoreactivity for the vascular endothelial growth factor (VEGF), which is implicated in angiogenesis and osteogenesis, in the sternum of fetal mice following magnetic exposure. Our studies also indicated that on day 16.5 of gestation following SMF exposure, the immunoreactivity for VEGF was increased compared to unexposed controls. However, it was decreased in the exposed group compared to the control group on day 18.5 of gestation. DNA and proteoglycan (PG) synthesis were also measured in rabbit costal growth plate chondrocytes in vitro. No significant differences were observed in DNA synthesis between the SMF exposed chondrocytes and the control chondrocytes; however, PG synthesis in SMF exposed chondrocytes increased compared to the controls. Based on these results, we suggest that while SMF exposure promoted the endochondral ossification of chondrocytes, it did not induce any harmful effects on fetal development in ICR mice.View full abstractDownload PDF (444K) -
MADHU BALA, A. K. SHARMA, H. C. GOELArticle type: Regular papers
2001 Volume 42 Issue 3 Pages 285-294
Published: 2001
Released on J-STAGE: December 04, 2001
JOURNAL FREE ACCESSWe have studied the effects of 2-deoxy-D-Glucose (2-DG) on the recovery of potentially lethal damage (PLDR), repair of chromosomal DNA, cyclobutane pyrimidine dimers (CPDs), reverse mutation and gene-conversion in UVC (254 nm) irradiated yeast. As studied by pulsed-field gel electrophoresis, post-irradiation chromosomal DNA repair kinetics in a phosphate buffer (PB) with 10 mM glucose (G) was biphasic, where the first phase exhibited a decrease and the second phase showed an increase in the band intensities. A post-irradiation treatment in PB+G (10 mM) with 2-DG (10, 20, 50 mM) reduced the decrease in the DNA band intensities in the first phase of DNA repair. As compared to a post-irradiation (125 J/m2) treatment in PB+G (10 mM), a treatment in PB+G (10 mM)+2-DG (10 mM) showed a decreased PLDR, but increased revertants and gene-convertants.View full abstractDownload PDF (279K) -
JUN HIDEMA, IL-KYUNG SONG, TADASHI SATO, TADASHI KUMAGAIArticle type: Regular papers
2001 Volume 42 Issue 3 Pages 295-303
Published: 2001
Released on J-STAGE: December 04, 2001
JOURNAL FREE ACCESSAmong Indica rice cultivars (Oryza sativa L. cvs.) that belong to the aus ecotype from the tropical Bengal region, where the amount of ultraviolet-B (UV-B) radiation in the solar radiation is relatively great, Marich-bati cultivar has exhibited resistance to UV-B radiation, while Surjamkhi cultivar appeared to be less resistant. We have examined the susceptibility to cyclobutane pyrimidine dimer (CPD) induction by UV-B radiation and the ability to photorepair CPDs using these two cultivars. UV-B radiation produced similar dimer levels in the leaves of the two cultivars. In contrast, the ability to photorepair CPDs in the UV-sensitive Surjamkhi cultivar was lower than that in the UV-resistant Marich-bati cultivar. These results were similar to our previous data, namely, that a UV-sensitive Japanese rice cultivar (Oryza sativa L. cv. Norin 1) cultivated in the moderate climate of Japan is deficient in its ability to photorepair CPDs. Thus, these results suggest that a strong correlation exists between the sensitivity to UV-B and the photorepair deficiency, and that a low ability in CPD photorepair may be a principal factor in determining the UV-B sensitivity in rice plants.View full abstractDownload PDF (64K) -
CHUNLIN SHAO, MIZUHO AOKI, YOSHIYA FURUSAWAArticle type: Regular papers
2001 Volume 42 Issue 3 Pages 305-316
Published: 2001
Released on J-STAGE: December 04, 2001
JOURNAL FREE ACCESSThe mechanisms of medium-mediated bystander effects on cell survival and micronucleus (MN) induction were investigated by co-cultivating unirradiated HSG cells with cells irradiated by X-rays or 290 MeV/u carbon beams. It was found that the survival of the irradiated cells exponentially decreased along with the dose, and that the plating efficiency (PE) of the unirradiated recipient cells was obviously more enhanced than that of the control cells. Moreover, MN was induced in the unirradiated recipient cells and its yield had a maximum distribution corresponding to the donor dose, which was different from the linear-quadratic dose response of the yield of MN in the irradiated cells. The treatment of PTIO, a scavenger of nitric oxide (NO), decreased both PE and MN of the unirradiated recipient cells to control levels. Moreover, nitrite was detected in the co-culture medium, and its concentration was related to the donor dose. These results indicated that NO was involved in the above mentioned medium-mediated bystander effects. In addition, an equation was deduced to well fit the induction of MN of the unirradiated recipient cells.View full abstractDownload PDF (89K) -
NORIKO USAMI, AKINARI YOKOYA, SHOZO ISHIZAKA, KATSUMI KOBAYASHIArticle type: Regular papers
2001 Volume 42 Issue 3 Pages 317-331
Published: 2001
Released on J-STAGE: December 04, 2001
JOURNAL FREE ACCESSThe characteristics of DNA lesions produced by the photoabsorption of phosphorus in yeast cells were studied using monochromatized soft Xrays tuned to the absorption peak of the phosphorus K-edge (2153eV) and below the peak energy (2147 eV). The repaired fractions of DNA double-strand breaks (dsb) were measured relatively by using both a mutant, rad54-3, which shows the temperature-sensitive dsb repair-deficient phenotype, and a wild-type strain. The repaired fraction of lesion in rad54-3, which corresponds to the relative yield of dsb reparable by the RAD54 pathway, was not affected by the phosphorus photoabsorption. Repair of the produced lesions in the wild-type cells was also measured by comparing the surviving fraction of the immediately plated cells to that of those cells plated after holding in a non-nutrient medium for 80hrs. The recovery of the surviving fraction after the holding treatment was dependent upon the irradiated X-ray energy. These results suggest that irreparable lesions are produced by the inner-shell photoabsorption of phosphorus in DNA, although its yield is small.View full abstractDownload PDF (101K)
- |<
- <
- 1
- >
- >|