UC Irvine

The sequence complexity of nuclear total RNA and nuclear poly(A)+RNA from Drosophila third-instar larvae was determined by hybridization of these RNAs to labeled single-copy DNA. At saturation, the nuclear poly(A)+ - and total RNA hybridized to 11% and 22.5% of the single-copy DNA, respectively. The increase in complexity of nuclear total RNA over that observed for nuclear poly(A)+RNA indicates the presence of a discrete class of nonoadenylylated nuclear RNA molecules. The relationship between DNA sequences coding for nuclear RNA and mRNA was then determined by hybridization of nuclear total and poly(A)+RNA to DNA enriched for mRNA coding sequences. The results of these studies show that those single-copy DNA sequences that are represented in either the poly(A)+ - or poly(A)- mRNA population are transcribed into RNA molecules that appear in the nuclear poly(A)+RNA population.