Preliminary characterization of the major RNA species from Plasmodium falciparum.

Polyacrylamide gel electrophoresis of the total RNA extracted from cultures of Plasmodium falciparum resolved two major RNA components with estimated molecular weights of 1.3 X 10(6) and 0.72 - 0.74 X 10(6). Oligo(dT)-cellulose column chromatography of the total cellular RNA indicates that more than 90% of the total radiolabeled RNA lacks substantial poly(A) sequences (poly(A)-). Resolution of the poly(A)- fraction on polyacrylamide or agarose gels indicates that the majority of the poly(A)- RNAs are the 1.3 X 10(6) and 0.72 - 0.74 X 10(6) species. This observation was confirmed by two-dimensional oligonucleotide fingerprint analysis of the total cellular RNA as well as the poly(A)- RNA components. Oligonucleotide fingerprint analysis confirmed that the small RNA species is not a breakdown or cleavage product of the larger RNA component. Base ratio analysis of the large and small RNA species indicate that they are typically protozoan type with a low guanine + cytosine (G + C) content. The findings that these two RNA species (i) are the major cellular RNA species, (ii) lack substantial poly(A) sequences, (iii) have estimated molecular weights similar to the ribosomal RNAs obtained from other protozoa, (iv) have a low G + C content (approximately equal to 35 - 37%), and (v) are distinct from one another, indicates that the 1.3 X 10(6) and 0.72 - 0.74 X 10(6) RNA components obtained from P. falciparum cultures are the major ribosomal RNAs.