Molecular cloning and characterisation of the ribC gene from Bacillus subtilis: a point mutation in ribC results in riboflavin overproduction.

A mutation leading to roseoflavin resistance and deregulated riboflavin biosynthesis was mapped in the genome of the riboflavin-overproducing Bacillus subtilis strains RB52 and RB50 at map position 147 degrees. The chromosomal location indicates that the deregulating mutation in RB52 and RB50 is an allele of the previously identified ribC mutation. We cloned the ribC gene and found that it encodes a putative 36-kDa protein.

Forebrain-enriched RNAs of the canary: a population analysis using hybridization kinetics.

Canaries and other songbirds offer unique advantages for analyzing the relationship between specific gene regulation and neural plasticity. To establish a quantitative profile of the population of RNAs potentially involved in this regulation, we analyzed the solution hybridization kinetics of canary forebrain cytoplasmic polyadenylated RNA. Hybridization of forebrain cDNA to forebrain RNA provides evidence for RNA species at individual concentrations ranging from less than 10(-6) to about 10(-3) (by fractional mass).

Probes for rare mRNAs reveal distributed cell subsets in canary brain.

cDNA clones of 7 low-abundance canary brain RNAs hybridize in situ to different subsets of brain cells. Although these cell sets are distinct, they are dispersed in a variety of brain regions with overlapping anatomical distributions. These cDNA clones were initially selected by their relative hybridization to forebrain and rest-of-brain RNAs and represent a sampling of a much larger population of differentially expressed RNAs present at individual concentrations of 10(-7) to 10(-4) as a fraction of polyadenylated RNA mass.

Apparent generation of a segmented mRNA from two separate tandem gene families in Trypanosoma cruzi.

Using a cDNA for an abundant Trypanosoma cruzi mRNA as probe, we have cloned and sequenced a gene which is organized in at least 20 nearly perfect tandem repeats of 940 base pairs. The 5' end of the mRNA has been sequenced by primer extension and found to contain a 35 nucleotide mini-exon (or spliced-leader) sequence that is ubiquitous in trypanosome mRNAs. This sequence, however, is not present in the tandem genomic repeats which encode the exon containing the major portion of the mRNA.

Minichromosomal repetitive DNA in Trypanosoma cruzi: its use in a high-sensitivity parasite detection assay.

We have isolated genomic clones containing members of a tandemly repeated DNA family from Trypanosoma cruzi. This family, which contains a 195-base pair (bp) repeating unit, is the most abundant repetitive DNA in this organism. DNA sequencing analysis of three adjacent tandem repeats as well as two independent nonadjacent repeats showed relatively little sequence heterogeneity.