Project description:In the present study, the susceptibility of the purple pigmented photosynthetic alphaproteobacterium Rhodospirillum rubrum S1H to gamma irradiation was investigated and its molecular response was characterised by means of gene expression analysis. R. rubrum S1H appears to be about 4 times more sensitive than the model strain Escherichia coli MG1655 to cobalt-60 gamma irradiation. Whole genome response of R. rubrum to 25 Gy revealed the common expression of SOS response related genes in both rich and minimal media. Quantitative expression of the lexA gene was followed after various recovery time following gamma irradiation and showed differential gene expression pattern between minimal and rich medium. This work paves the way for forthcoming molecular studies on the effect of ionizing radiation on R. rubrum S1H and the other MELiSSA strains. Keywords: Rhodospirillum rubrum; ionizing radiation tolerance; microarray; quantitative PCR.
Project description:In the context of the Micro-Ecological Life Support System Alternative (MELiSSA) project, the quorum sensing system (QS) of R. rubrum S1H has been shown to rely on acyl homoserine lactones (AHLs) as communication signals. In addition, previous studies in our lab have suggested that pigment content and photosynthetic membrane production could be under the control of QS. In the present study, the transcriptomic and proteomic profiles of a QS-deficient mutant (R. rubrum strain M68) that does not produce AHLs as the WT strain (R. rubrum S1H) were compared when cultivated in light anaerobic conditions using acetate as carbon source. Transcriptomic and proteomic approaches revealed that 330 genes and 217 proteins were differentially expressed in M68 compared to S1H, indicating that several operons were QS-regulated i.e. flagellar assembly, chemotaxis, photosynthesis, electron transport, stress proteins. These results showed the importance of a functional QS system in R. rubrum.
Project description:In the present study, the susceptibility of the purple pigmented photosynthetic alphaproteobacterium Rhodospirillum rubrum S1H to gamma irradiation was investigated and its molecular response was characterised by means of gene expression analysis. R. rubrum S1H appears to be about 4 times more sensitive than the model strain Escherichia coli MG1655 to cobalt-60 gamma irradiation. Whole genome response of R. rubrum to 25 Gy revealed the common expression of SOS response related genes in both rich and minimal media. Quantitative expression of the lexA gene was followed after various recovery time following gamma irradiation and showed differential gene expression pattern between minimal and rich medium. This work paves the way for forthcoming molecular studies on the effect of ionizing radiation on R. rubrum S1H and the other MELiSSA strains. Keywords: Rhodospirillum rubrum; ionizing radiation tolerance; microarray; quantitative PCR. Two-condition experiments. Comparing samples after exposure to gamma (Co-60) irradiation with a non-irradiated sample. At least biological duplicates. Each array contains 3 technical replicates.
