The Nucleolar Organiser Regions (NOR) contain clusters of genes which code for the three largest structural rRNA molecules (5.8S, 18S and 28S).
These rRNA genes are critically important for the viability of the cell and represent around 0.5% of the human diploid genome. They are found in the short arm of the acrocentric chromosomes and are the region around which the nucleoli develop at the end of mitosis1.
A NOR can translocate to a terminal region of another chromosome. In rare instances this can be pathogenic, particularly when the translocation has led to a deletion at the tip of the recipient chromosome2. It has been suggested that the restructuring of the rRNA genes is the most common chromosomal alteration in adult solid tumours3.
In routine cytogenetic analysis, NOR can be used to delineate marker chromosomes through a process of silver staining the NOR (known as AgNOR staining4). However, the technique relies on translation of protein and if this is not present, conventional silver staining will not stain the NOR. Cytocell's FISH probe has been developed to overcome this problem so that presence of the acrocentric chromosomes in the marker can be detected.
The quality of the products we have received from CytoCell have been excellent. The FISH probes they provide to us give intense, strong signals and are a pleasure to count. What has really stood out however has been the level of support and assistance provided by CytoCell’s application specialists. The team worked very closely alongside our own during the adoption of this product and spent many hours with us perfecting the technique, going above and beyond what I would expect during the transition period. Source BioScience absolutely demand high quality products and service to be able to deliver our results with confidence, and that is what we have received from CytoCell.
Laboratory Operations Manager, Source BioScience, UK