RDNA and nucleologenesis in drosophila

Abstract

The study of Drosophila ribosomal DNA (rDNA) dates back to the first bobbed mutations discovered by T.H. Morgan's group nearly 100 years ago. From these earliest discoveries to the current day, Drosophila has proven to be a valuable system to study the genetic, molecular, and cellular aspects of rDNA in ribosome biogenesis. Our goal in writing this review was to describe the various aspects Drosophila rDNA, but within a historical context. We describe Drosophila nucleolar organizers and their flanking heterochromatin, how intergenic regions function in X-Y chromosome pairing, the fundamentals of Drosophila rDNA magnification and compensation, the fascinating biology of R1 and R2 retrotransposons and their mechanism of transposition, and the latest work on how rDNA acts as an epigenetic regulator of genome-wide gene expression in Drosophila. Expression of the rDNA itself is the driving mechanism in nucleologenesis (the formation of nucleoli), and we describe how Drosophila has contributed to our understanding of nucleologenesis. With the nucleolus now considered an important stress sensor within the cell, Drosophila will likely provide new insights into cell homeostasis as regulated by the nucleolus.