PROCESSING OF VERTEBRATE BOX C D SMALL NUCLEOLAR RNAS IN PLANT-CELLS/

The recent isolation of a number of plant box C/D small nucleolar (sno )RNAs demonstrates the conservation in plants of sequence and structur al elements of processed box C/D snoRNAs. Boxes C and D, and terminal inverted repeats are known to be essential far accumulation and proces sing in vertebrates and yeast. Processing of vertebrate box C/D snoRNA s was examined by expression of various mouse hsc70 intron 5-U14 const ructs in tobacco protoplasts. Full-length U14 and internally deleted U 14 accumulated in the plant cells. Human U3 and U8 fragments, consiste nt with processing to internal box C/C' sequences, also accumulated in the plant cells. The similarity of processing behaviour of the verteb rate box C/D constructs in tobacco protoplasts and Xenopus oocytes sug gests the mechanism of processing, involving recognition and associati on of proteins, is conserved in plants.