SYMMETRICAL CHROMOSOMAL ORDER IN LEUKOCYTES INDICATED BY DNA IMAGE CYTOMETRY AND FLUORESCENCE IN-SITU HYBRIDIZATION

OBJECTIVE: To study if the symmetry observed in the nuclear structure of polymorphonuclear cells (PNC) could be verified functionally by det ermining DNA and chromosome distributions using image cytometry (ICM) and fluorescence in situ hybridization (FISH). STUDY DESIGN: In murine and human leukocytes the proportion of PNCs with apparently bilateral ly symmetric nuclei was determined. By ICM, total nuclear DNA and DNA content in each half of these nuclei were measured. For chromosomal lo calization the FISH technique was applied. RESULTS: About 13% of PNC n uclei appeared to be bilaterally symmetric. ICM of Feulgen DNA reveale d that the PNC had a 2N value, similar to mononuclear cells. The DNA c ontent in each of the two symmetric parts of the nucleus was exactly t he same. Similarly, FISH signals specific to chromosomes 1 and 2 were distributed bilaterally on the two symmetric parts. CONCLUSION: The di stribution of DNA and chromosomes studied support the hypothesis of bi lateral symmetry of PNC nuclei, suggesting haploid separation. This sp ecific distribution may be valuable for the study of mechanisms leadin g to DNA and chromosome damage by exposures to chemicals or radiation and may have far-reaching significance in genetics regarding imprintin g, meiotic pairing and other subjects.