Increase In Chromosome Damage Research Articles

Response to X-rays of dormant and non-dormant seeds of Triticum durum desf

The X-ray sensitivity of dry seeds of durum wheat at different levels of dormancy was examined. Two doses of X-ray exposures (1000 and 5000 R) were utilized and analysis was carried out on cells from root to tip meristems of seeds allowed to germinate on moistened filter paper for different times. The results showed that the 1000 R dose did not increase the spontaneous chromosome damage in deep dormant seeds, while inducing a 100% increase in chromosome damage in lightly dormant and in non-dormant seeds. The deep dormant seeds irradiated with 5000 R showed a chromosome damage lower than that of both lightly dormant and non-dormant seeds. The chromosome damage was of chromatid type (B′) at 1000 R, irrespective of the physiological condition of the seeds. On the contrary, the lightly dormant or non-dormant seeds irradiated with 5000 R showed both chromatid and chromosome (B″) damage; the deep dormant seeds exhibited B′ damage only. The lack of B″ damage in root meristems from deep dormant seeds is likely to be due to (i) the physiological state of seeds which causes a slow germination and a possible delay of mitosis initiation at germination, (ii) a more efficient repair process or a greater radiation resistance bound to the metabolic condition of the deep dormant seeds.

The influence of temperature on chromosome aberrations in tissue culture: Relation to thermal aging

Chromosome aberrations were scored in V-79 strain Chinese hamster cells grown in vitro. The percent of aberrant mitoses observed in anaphase and early telophase increased significantly with temperature over the range of values between 35° and 40°C. No significant increase in aberration percentage was observed when the culture growth time was extended from 2 to 3 days. The progressive increase in chromosome damage with temperature supports the concept that genetic information is thermally degraded even at temperatures in the normal physiological range. Since an increase in chromosome aberration frequency is correlated with aging, it may be that thermally induced information loss is an important factor in the aging process. However, the dependence of the aberration percentage on temperature is not sufficiently strong to fully explain the thermal loss of proliferative capacity of cells in culture. Additional temperature-dependent processes must occur and may further contribute to the thermal destruction of cellular information.

The effect of caffeine on chromosomes of human lymphocytes: In vivo and in vitro studies

Lymphocytes in culture from human volunteers on a regimen of 800 mg of caffeine daily (4×200 mg) for one month manifested no significant increase in chromosome damage. The highest level of caffeine in the plasma was 30 μg/ml. Multiple exposures of lymphocyte cultures from other untreated donors to this concentration (30 μg/ml) was also without chromosome-damaging effect. However, single exposure of cells at the 48th h of culture produced damage in the 250–750 μg/ml range. These findings were the result of experiments with the lymphocytes from the same four individuals tested on three separate occasions. Earlier additions at concentrations below 250 μg/ml produced no significant breakage.

The effect of fetal heart monitoring by ultrasound on maternal and fetal chromosomes.

SummarySince the initial report that ultrasound radiation at diagnostic frequencies and power levels causes chromosome damage in vitro several investigators have tried unsuccessfully to confirm this. The purpose of the present study was to determine if chromosome damage could be demonstrated following fetal heart monitoring in vivo. White blood cells from ten mothers and from the cords of their newborn infants after 2 to 10 hours of fetal heart monitoring during labour were cultured and scored for chromosome damage. When the irradiated samples were compared to controls no increase in chromosome damage was found.

Effects of SV40 virus on the chromosomes of poikilothermic cells (Gekko gecko) cultivated at different temperatures.

AbstractCells of an established cell line of poikilothermic origin (Gekko gecko) were transformed with SV40 virus and maintained at three temperatures: 23°, 30°, and 35°C. Cytogenetic analysis was undertaken at various times following infection. Increased chromosome damage, related to both incubation temperature and the length of time in culture, was observed in the virus‐transformed cells. A new “tetraploid” stem line arose in those cells cultured at 30°C; the presence of pairs of identical marker chromosomes suggests that this new stem line was derived through endoreduplication rather than the fusion of two cells.

Studies on the lymphocytes of patients with renal homografts.

SUMMARY Several reports of an increased incidence of malignant disease in renal homograft patients, who were under immunosuppression, led us to consider the possibility of chromosome damage to the lymphocytes in such patients. Peripheral blood samples from 19 renal homograft recipients and 19 patients being treated by haemodialysis were studied. Chromosome damage in excess of normal levels was observed in the lymphocytes of both groups. The damage in the homograft patients could be attributed almost exclusively to radiation therapy. There was no evidence of increased chromosome damage in immunosuppressed patients who had not been irradiated. No obvious explanation could be found for the elevated levels of chromosome damage in the dialysis patients. The response of the lymphocytes to phytohaemagglutinin (PHA) was depressed in the homograft patients.

Effect of LSD-25 on mitotic and meiotic chromosomes of mice and monkeys.

Chromosomal studies were carried out in bone marrow and testes of mice treated with lysergic acid diethylamide (LSD-25) in acute and chronic experiments, in blood cultures of rhesus monkeys (Macaca mulatta) treated with LSD-25 in vitro, and in blood cultures and testicular preparations of rhesus macaques treated with LSD. No increase in chromosomal damage was observed in bone marrow or testes, but all blood cultures treated with LSD in vitro and some of the blood cultures from rhesus macaques treated in vitro showed a significant increase in chromosomal breaks and rearrangements.

Chromosomal Damage in Human Leukocytes Induced by Lysergic Acid Diethylamide

Addition of lysergic acid diethylamide to cultured human leukocytes resulted in a marked increase of chromosomal abnormalities. The distribution of chromosome breaks deviated significantly from random, with an accumulation of aberrations in chromosome No. 1. Cytogenetic investigation of a patient extensively treated with this drug over a 4-year period for paranoid schizophrenia showed a similar increase in chromosomal damage.