ISAC XX Abstracts on Disc Presented by Purdue University Cytometry Laboratories

FEATURES OF CHROMOSOMES IN HUMAN TERMINALLY DIFFERENTIATED BRONCHIAL CELLS PROVIDE A BLUEPRINT FOR NUCLEAR ORGANIZATION.

Leoplod G. Koss Montefiore Medical Center Central Bldg. 3rd Floor Dept. of Cytology 111 East 210th Street Bronx, NY, USA, 10467

Abstract Number: 6364     Established Technologies  –  Other Established Technologies

With FISH painting technique of terminally differentiated ciliated bronchial and goblet cells, it was shown that the two homologues of each chromosome occupy a separate domain on or adjacent to the nuclear membrane. One of the homologues was usually more "compact" than the other which was more "open," displaying fiber-shaped extensions. The differences between the territories of homologues 1 and 7 were statistically valid (p<0.0001). In some arrays of bronchial cells, the position of the homologues was either identical or formed a mirror image, suggesting that the position of the chromosomes may be constant. To confirm this observation, the angles formed by the homologues X, 1 and 7 were measured in oval nuclei. In about 2/3 of the nuclei, the two homologues formed angles of 150, 157 and 148 degrees, identical to those formed by the same chromosomes in prometaphase rosettes of diploid human fibroblasts (Nagele et al., 1995). In about one third of the nuclei, the same homologues formed angles of 89, 72, and 94 degrees, and occasionally an angle of 180 degrees. A three-dimensional computer reconstruction of the nuclei was performed using the data for X chromosomes. By cinematographic technique, it was shown that the angles separating the 2 homologues depended on the rotation of the nucleus. The cause of the rotation is speculative at this time. It is suggested that the position of chromosomes in interphase human cells is constant and that the 2 homologues of each chromosome are not identical. These observations may have considerable bearing on chromosomal translocations, the formation of the nuclear membrane and of nuclear pores.

Keywords: nuclear organization, normal chromosome territories, nuclear membrane