Toshio Sofuni

CHROMOSOME-ABERRATION FREQUENCY IN CULTURED BLOOD-CELLS IN RELATION TO RADIATION DOSE OF A-BOMB SURVIVORS

Abstract 243 heavily exposed survivors of the atomic bombings of Hiroshima and Nagasaki and 213 distally exposed controls of all ages were examined cytogenetically. Using a 2-day-culture method, it was found that there was an increase in the frequency of cells with radiation-induced chromosome aberrations proportional to radiation dose. Cells with stable-type aberrations, such as translocations and pericentric inversions, predominated, although cells with dicentrics and rings were also present to a lesser degree. All these aberrations were greater in frequency in the exposed than the controls. In-vivo clones of aberrant cells were seen in 14 heavily exposed persons. The two cities differed in frequencies of stable and unstable aberrations in each dose group, but the reason for this difference is not known.

Paracentric inversion of a human chromosome 7

SummaryIn the course of chromosome studies of atomic bomb survivors in Hiroshima using the trypsin-G-banding and Q-banding methods, a 40-year-old male was found to have an abnormal banding pattern in the long arm of a chromosome 7, although no such abnormality was detected by ordinary staining method. Since all other chromosomes apparently had normal banding patterns, the abnormality was determined to be a paracentric inversion of a chromosome 7, which is described as 46,XY,inv(7)(q22q31). This is the first demonstration of a possible paracentric inversion in man.

Chromosome heteromorphisms in the Japanese

SummaryThe nucleolus organizer regions (NORs) of variant D- and G-group chromosomes characterized by enlargements of the short arms including secondary constrictions and satellites, were examined using the silver-staining method. Of a total of nine variants examined, four were found to have double Ag-stained NORs in the enlarged short arm, two were found to involve chromosome 22, one was a 13, and one, a 14. Four of the other variants had only one Ag-stained NOR. From the positions of the NORs, three of them were judged to have enlarged satellites (two chromosomes 15 and one 22) and the other an enlarged short arm (a 15). In the remaining variant (a 14), no Agstained material was noted in the short arm, so it could not be determined whether this variant chromosome was derived from the enlargement of the short arm or from satellites. Based on the position of the Ag-stained NORs and staining intensity of the Q and C methods in the short arms, mechanisms of producing the enlarged short arms of D- and G-group chromosomes are discussed.

Preliminary Reanalysis of Radiation-Induced Chromosome Aberrations in Relation to Past and Newly Revised Dose Estimates for Hiroshima and Nagasaki A-Bomb Survivors

A comparison of the chromosome data from 408 atomic bomb survivors, 229 in Hiroshima and 179 in Nagasaki, was performed in terms of the frequency of cells with radiation-induced chromosome aberrations plotted against the existing A-bomb dosimetry system (T65D), and the new dosimetry systems from ORNL (Oak Ridge National Laboratory) and LLNL (Lawrence Livermore National Laboratory). Preliminary analysis-shows that the inter-city difference in aberration frequencies is still apparent at every T65D dose level, while the aberration frequencies based on both ORNL and LLNL systems do not differ strikingly between the two cities, particularly in the dose range below 200 rad.

A new type of inversion of a human Y chromosome

SummaryUsing chromosome banding techniques, a phenotypically normal male was found to have an abnormal banding pattern of the Y chromosome. By the constitutive heterochromatin staining method, a darkly stained band was located on the short arm and the proximal region of the long arm. The quinacrine staining method also showed a similar abnormal banding pattern: a brightly fluorescing band was seen on the short arm and the proximal region of the long arm. By the conventional Giemsa staining method, however, no specific morphological abnormality was detected in the aberrant Y. On detailed karyotype analyses no recognizable abnormality of banding patterns of any other chromosome was found aside from the abnormal Y. The abnormality was determined to be a complex inversion of the Y chromosome, which is described as 46,X,inv(Y)(pter→p11::q11→q12::cen::q12→qter).

An XY human female with ovaries

Abstract A female patient hospitalized with primary amenorrhea was studied cytogenetically. The case was diagnosed clinically and pathologically as afollicular ovarian dysgenesis, with the presence of a vagina, a uterus, bilateral Fallopian tubes, and the absence of testes as well as of the somatic signs of Turners syndrome. Chromosome studies were carried out on cultured leukocytes and fibroblasts derived from several different organs. It was found that the patient had an apparently normal male chromosome constitution of 46, XY and that the deoxyribonucleic acid-replicating pattern and the fluorescent-staining property observed in cultured leukocytes of this patient were consistent with that of normal male cells. The possible mechanisms for the occurrence of the XY sex constitution in a phenotypical female are discussed.