Project description:Oral streptococci, including Streptococcus gordonii, and Actinomyces naeslundii, are consistently found to be the most abundant bacteria in the early stages of dental plaque accumulation. These organisms interact physically (coaggregate) in vitro and in vivo. We hypothesized that coaggregation between S. gordonii and A. naeslundii leads to changes in gene expression in the partner organisms. Furthermore, we predicted that coaggregation-induced changes in phenotype contribute to the success of streptococci and actinomyces in dental plaque. To assess the responses of S. gordonii to coaggregation with A. naeslundii, RNA was extracted from S. gordonii cells 3 h after inducing coaggregation with A. naeslundii or from equivalent S. gordonii monocultures. The two RNA populations were reverse transcribed and compared by competitive hybridization with an S. gordonii genomic microarray. The most striking feature of the response to coaggregation was a profound change in expression of S. gordonii genes involved in arginine biosynthesis and transport. Subsequent experiments demonstrated that coaggregation with A. naeslundii stabilizes arginine biosynthesis in S. gordonii and enables growth under low-arginine conditions, such as those present in human saliva. Keywords: Cell-cell interaction
Project description:The transcript profiles of Nesterenkonia sp. AN1 grown at 5 ºC (Cold) and 21 ºC (Topt) were acccessed to evaluate the cold reposnse of this Antarctic Nesterenkonia strain. The strain was grown in triplicates at the optimum growth temperature of 21 ºC and a test temperature of 5 ºC. Total RNA was extracted from two replicate samples for each treatment condition and the total RNA was enriched for mRNA. RNA-seq was done using Illumina Miseq platform at Inqaba Biotech, South Africa. The reads were mapped against the genome sequence of Nesterenkonia sp. AN1 (obtained from NCBI database) and assesed for differeential gene expression using CLC Genomics Workbench 7.5. Evaluation of RNA-seq data for Nesterenkonia sp. AN1 at 5 ºC (Cold) and 21 ºC (Topt) in two biological replicates