CHARACTERIZATION OF PUTATIVE SMALL NUCLEAR RNAS FROM GIARDIA-LAMBLIA

Small nuclear RNAs (snRNAs), which have roles in RNA metabolism, have been found in all eukaryotic cells. Candidate snRNAs were identified i n the primitive protozoan parasite, Giardia lamblia, by either immunop recipitation of total RNA with antiserum directed against the 2,2,7-tr imethylguanosine cap structure characteristic of snRNAs or by Northern hybridization with oligonucleotide probes complementary to snRNA cons ensus sequences. Isolated putative snRNAs include eight 2,2,7-trimethy lguanosine-capped species: RNAs A through H, and one non-2,2,7-trimeth ylguanosine-capped species: RNA J. Single copy genes encoding RNA D, R NA H and RNA J were cloned and sequenced, and the 5' end of each RNA w as determined by primer extension analysis. Certain characteristics su ggest tentative identification of these Giardia RNAs as nucleolar RNAs with possible roles in rRNA processing.