volume 10 Number 31982 Nucleic Acids Research A novel species of donble stranded RNA in mitochondria of Saccharomyces cerevisiae

A double stranded RNA species has been detected 1n guanidine hydrochlor-1de extracts of nrttochondrfa from respiratory competent cel ls of Sacch<vwmy-CSJ> C£AZ\MJUM.. This novel mitochondrial RNA, termed mtdsRNA, has been pur i f ied 1n a CS2SO4 density gradient where i t bands at a density of 1.58 g/ml. The nrtdsRNA runs as a single slow moving band on agarose gels. I t s double stranded RNA character was evidenced by I t s sens i t i v i t y to digestion by RNase T i l, but not by RNase H, or DNase I. Moreover the mtdsRNA hybrid-ized to each separated strand of a pet i te mtDNA. I t 1s concluded that nrtdsRNA contains long transcripts derived from most regions of yeast mtDNA, because 1) i t s weight-average length as determined by electron microscopy was 4.5 um (about 14 kb, or 20J of the wi ld type mtDNA genome), and 2) 1t hybridized to each of a series of eight pet i te mtDNA probes carrying sequences derived from widely d i f ferent segments of mtDNA. I t 1s proposed that prolonged transcr ipt ion of both strands of yeast mtDNA can occur and that mtdsRNA arises from hybridization of these long complementary transcr ipts