Essay on the nucleoli survey by the alpha- and beta-satellite DNA probes of the acrocentric chromosomes in mitogen-stimulated human lymphocytes.

ABSTRACT

The two constitutive heterochromatin (alpha- and beta-satellite DNA) probes of human acrocentric chromosomes were assayed separately to label the nucleoli in the phytohemagglutinin (PHA)-stimulated human lymphocytes. Fluorescent in situ hybridisation (FISH) results have shown that a) whole (100%) signal-nucleoli overlapping was obtained with both heterochromatin probes in maximally activated nuclei (MANs); b) partial overlapping was observed in non-activated or slightly activated nuclei; c) random signal-nucleolus overlapping (background level) was found to be approximately 6% by the NOR-irrelevant euchromatic probe (D5S23); d) Yq-nucleolus association in the MANs was found to be approximately 97% without the subtraction of the background level. We concluded that a) acrocentric alpha- or beta-satellite DNA probes may be used as nucleolar markers only in the MANs and not in slightly activated or non-activated nuclei; b) the distances between rDNA loci and alpha-/beta-satellite DNA on human acrocentrics are short enough to permit their observation on the same nucleolus.