FAMILIAL SILVER STAINING PATTERNS OF HUMAN NUCLEOLUS ORGANIZER REGIONS (NORS)

  • 1 January 1981
    • journal article
    • research article
    • Vol. 33  (1) , 67-76
Abstract
Ag staining patterns of the nucleolus organizer regions (NOR), an indication of r[ribosomal]DNA transcriptional activity, were studied in metaphases from lymphocyte cultures of 20 karyotypically normal members of 3 families selected for a large sibling number or a monozygotic twin pair. Quinacrine polymorphic markers and bands were used to identify the acrocentrics and to determine their parental origin. A comparison of the Ag staining frequencies among siblings and between parent and child indicated no significant differences for any acrocentric in the twin pairs and significant differences (P < 0.05) for only 1 of the 20 acrocentrics segregating in each of 2 families. These 2 acrocentrics had short stalks with very small Ag deposits (AgNORs). The mean size of the AgNOR, based on a relative score, was not significantly different (P > 0.05) for each homolog between the twin pair and in approximately 70% of the acrocentrics shared by members of the 1 family analyzed. The frequency with which a particular chromosome was Ag stained demonstrated a significant correlation (r2 = 0.732) with the size of AgNOR. There was a close correlation (r2 = 0.609) between stalk length and the size of the AgNOR. The frequency of Ag staining and the mean size of the AgNOR are characteristics inherent in a particular chromosome carried from one generation to the next.