The production of micronuclei from chromosome aberrations in irradiated cultures of human lymphocytes.

@article{Countryman1976, abstract = {A rapid assay for chromosomal damage would greatly speed studies of the mechanism by which chromosomal aberrations are formed. The characteristics of such an assay--micronuclei produced in cultured human lymphocytes--are given here, together with the evidence that the assay accurately measures X-ray-induced chromosomal damage. Micronuclei arise from chromosomal fragments that are not incorporated into daughter nuclei at mitosis because they lack a centromere. In our experiments the response of lymphocytes from different donors was very uniform and agreed well with what was expected from metaphase analysis of aberrations: (1) the increase in micronucleus frequency begins at the time of the first mitoses, 48 hours after the cultures are started, (2) the exponent of the dose response equation (y=kDn) was 1.2 for micronuclei. For one-hit aberrations n=1 whereas for two-hit aberrations n=2. Since two-hit aberrations predominate in these cultures, a value of n= approximately 1.8 was expected if no increase in mitotic delay or cell death occurred at higher doses, and n less than 1.8 if an increase occurred, (3) the frequency of micronuclei was decreased by a factor of about two when the dose was fractionated, as expected when most of the aberrations are two-hit. The rejoining time for four or five donors was between 30 and 60 minutes, (4) the X-ray-induced micronucleus frequency in cells from people with Down's syndrome (trisomy-21) was twice that of control donors as expected from metaphase analysis [22,23]. Since the micronucleus assay reflects the aberration frequencies so well and is so fast, it is suitable for a rapid assessment of chromosomal damage.}, author = {Countryman, P. I. and Heddle, J. A. }, citeulike-article-id = {1452074}, doi = {http://dx.doi.org/10.1016/0027-5107(76)90105-6}, issn = {0027-5107}, journal = {Mutation Research}, keywords = {findthis, micronuclei}, month = {December}, number = {2-3}, pages = {321--332}, posted-at = {2007-07-12 14:24:46}, priority = {2}, title = {The production of micronuclei from chromosome aberrations in irradiated cultures of human lymphocytes.}, url = {http://dx.doi.org/10.1016/0027-5107(76)90105-6}, volume = {41}, year = {1976} }

TY - JOUR ID - Countryman1976 L3 - citeulike-article-id:1452074 TI - The production of micronuclei from chromosome aberrations in irradiated cultures of human lymphocytes. JF - Mutation Research VL - 41 IS - 2-3 SP - 321 EP - 332 SN - 0027-5107 N2 - A rapid assay for chromosomal damage would greatly speed studies of the mechanism by which chromosomal aberrations are formed. The characteristics of such an assay--micronuclei produced in cultured human lymphocytes--are given here, together with the evidence that the assay accurately measures X-ray-induced chromosomal damage. Micronuclei arise from chromosomal fragments that are not incorporated into daughter nuclei at mitosis because they lack a centromere. In our experiments the response of lymphocytes from different donors was very uniform and agreed well with what was expected from metaphase analysis of aberrations: (1) the increase in micronucleus frequency begins at the time of the first mitoses, 48 hours after the cultures are started, (2) the exponent of the dose response equation (y=kDn) was 1.2 for micronuclei. For one-hit aberrations n=1 whereas for two-hit aberrations n=2. Since two-hit aberrations predominate in these cultures, a value of n= approximately 1.8 was expected if no increase in mitotic delay or cell death occurred at higher doses, and n less than 1.8 if an increase occurred, (3) the frequency of micronuclei was decreased by a factor of about two when the dose was fractionated, as expected when most of the aberrations are two-hit. The rejoining time for four or five donors was between 30 and 60 minutes, (4) the X-ray-induced micronucleus frequency in cells from people with Down's syndrome (trisomy-21) was twice that of control donors as expected from metaphase analysis [22,23]. Since the micronucleus assay reflects the aberration frequencies so well and is so fast, it is suitable for a rapid assessment of chromosomal damage. KW - findthis KW - micronuclei AU - Countryman, PI AU - Heddle, JA PY - 1976/12// UR - http://dx.doi.org/10.1016/0027-5107(76)90105-6 ER -