Preservation of 23-S chloroplast RNA as a single chain of nucleotides

Determination of the half-life of chloroplast transcripts in tobacco leaves

The amounts of specific transcripts that accumulate in chloroplasts are determined by the rates of synthesis and degradation of the transcripts. The 3' untranslated region of transcripts is a major determinant of the stability of transcripts in chloroplasts. The half-lives of specific transcripts can be determined by northern blot analysis of a time course of transcripts in detached tobacco leaves incubated with actinomycin D, a potent transcription inhibitor. This analysis may be applied to transcripts of endogenous genes or of transgenes introduced into the chloroplast genome in transplastomic plants. Sequence determinants of transcript stability can be identified by analysis of transplastomic plants containing constructs of the green fluorescent protein (gfp) reporter gene fused to the sequences of interest.

Aspects of the relation between Cyanophora paradoxa (Korschikoff) and its endosymbiotic cyanelles Cyanocyta korschikoffiana (Hall & Claus) - III. Characterization of ribosomal ribonucleic acids

Analysis of ribosomal RNA from Cyanophora paradoxa (Korschikoff) demonstrated the existence of four species. Two species, 25 S and 18 S r-RNA, are characteristic of the host, while two other species, 23 S and 16 S , are characteristic of the endosymbiotic cyanelles, Cyanocyta korschikoffiana (Hall & Claus). The 23 S r-RNA from C. korschikoffiana was found to be labile and yielded degradation patterns resembling those seen in some chloroplast r-RNA preparations.

Characterization of 5.8S ribosomal ribonucleic acid in Neurospora crassa

Neurospora crassa ribosomes contain a species of ribonucleic acid (RNA) of molecular weight 54,000, similar to 5.8S ribosomal RNA previously described for other eukaryotic organisms. The 5.8S RNA from N. crassa was found to be released by heat treatment at 60 C from 25S ribosomal RNA but not from 18S ribosomal RNA. The base composition of N. crassa 5.8S RNA was similar to that of 5.8S RNA from Saccharomyces cerevisiae, but differed from animal 5.8S RNA. During the course of this study, it was discovered that N. crassa 25S ribosomal RNA had a number of internal cleavages that may exist in vivo.