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We describe the isolation of two rice chloroplast HindIII fragments (9.5 kb and 5.3 kb) each containing a gene cluster coding for the large subunit of ribulose-1,5-bisphosphate carboxylase (rbcL), beta and epsilon subunits of ATPase (atpB and atpE), tRNAmet (trnM) and tRNAval (trnV). All five genes contained in the 9.5 kb fragment are potentially functional, whereas in the 5.3 kb fragment, rbcL is truncated and atpB is frame-shift mutated. The copy number of the 9.5 kb fragment is 10 times that of the 5.3 kb fragment, indicating that the two fragments are probably located on different chloroplast genomes and represent two different (major and minor) genomic populations. Thus, the rice chloroplast genome appears to be heterogeneous, contrary to general belief. We also describe the isolation of a rice mitochondrial HindIII fragment (6.9 kb) which contains an almost complete transferred copy of this chloroplast gene cluster. In this transferred copy, the coding sequences of rbcL, atpE and trnM contain perfectly normal reading frames, whereas atpB has become grossly defective and trnV is truncated.

Sensory nerve endings of tongue mucosa of Cebus apella monkey were studied using the silver impregnation technique (WINKELMANN & SCHIMITT). Subepithelial sensory nerve endings of different forms are present in the medium and posterior parts of tongue mucosa. The nerve fibers have their origin in the deep layers of the tongue and form single and complex sensory nerve endings. The fungiform papillae contain numerous ramified nerve fibers, which constitute a subepithelia network, but the filiform papillae usually possess single free nerve endings disposed longitudinally into the connective tissue.

We report temperature-jump kinetic studies of the early melting transition of Escherichia coli 5S rRNA. A single measurable relaxation time tau, independent of concentration, was found at 266 nm. We monitored the transition temperature tm for this process (in the range from 0 to 40 degrees C) as a function of Mg2+, Na+, K+, spermidine, and H+ concentrations. Contrary to the usual effect of salts on nucleic acid stability, addition of mono- and multivalent counterions decreases tm for the early melting transition. Also unexpectedly, we found a strong dependence of tm on pH in the physiological range of 7--8. Quantitative analysis of the data indicates that about 0.7 protons are release when the ordered (low-temperature) form melts, whereas about 2 NA+ (or K+) and 0.5 Mg2+ are taken up by the melted (high-temperature) form. We estimate the enthalpy of the transition to be 15--20 kcal/mol (63--84 kJ/mol) and also report the forward and reverse rate constants and activation energies for the transition, along with the influence of ions on the transition dynamics. Diffusion constant measurements reveal that the low-temperature form has a frictional coefficient about 10% larger than that of the high-temperature form. The data imply a low-temperature tertiary structure capable of binding a proton. Increase of pH, temperature, or counterion concentration (all at near-physiological values) causes a tertiary conformational switch to a more compact form that has greater counterion binding but less proton binding. We discuss possible physiological roles for the transition.

We have isolated and sequenced the cytochrome oxidase subunit II (COII) gene from pea mitochondria. The coding sequence (777 bp) shows over 90% homology to the COII genes from three monocotyledonous plants (rice, maize and wheat) and one dicotyledonous plant (Oenothera berteriana). Several codons are deleted, however, in the pea COII gene. Of interest is the deletion in pea of the last three codons, including the stop codon, found at the 3' end of the other four COII genes. Instead, a new stop codon has been created due to a single-base substitution at the 13th bp downstream from the position of the original stop codon. This pea gene does not contain an intron which is found in all three monocots. Two distinct 5' termini of the pea COII transcripts have been identified by S1 nuclease mapping, one at 285 bp (site I) and the other at 302 bp (site II) upstream from the ATG codon. They are located at two identical sites within nearly perfect direct repeats. Transcripts with the 5' end corresponding to site I occur five time more frequently than those with the 5' end corresponding to site II. Both transcripts have the same 3' terminus which has been mapped to be at 193 to 195 bp downstream from the stop codon.

Full length cDNAs encoding the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from rat and man have been isolated and sequenced. Many GAPDH gene-related sequences have been found in both genomes based on genomic blot hybridization analysis. Only one functional gene product is known. Results from genomic library screenings suggest that there are 300-400 copies of these sequences in the rat genome and approximately 100 in the human genome. Some of these related sequences have been shown to be processed pseudogenes. We have isolated several rat cDNA clones corresponding to these pseudogenes indicating that some pseudogenes are transcribed. Rat and human cDNAs are 89% homologous in the coding region, and 76% homologous in the first 100 base pairs of the 3'-noncoding region. Comparison of these two cDNA sequences with those of the chicken, Drosophila and yeast genes allows the analysis of the evolution of the GAPDH genes in detail.