Project description:To explore the mechanisms of Salmonella desiccation resistance, we studied the transcriptomic responses in Salmonella Tennessee (Tennessee), using S. Typhimurium LT2 (LT2), a strain weakly resistant to desiccation, as a reference strain. In response to 2 h air-drying at 11% equilibrated relative humidity, approximately one-fourth of the ORFs in the Tennessee genome and one-fifth in LT2 were differentially expressed (> 2-fold). Among all differentially expressed functional groups (>5-fold) in both strains, the expression fold change associated with fatty acid metabolism was the highest, and constituted 51 and 35% of the total expression fold change in Tennessee and LT2, respectively. Tennessee showed greater changes in expression of genes associated with stress response and envelope modification than LT2, while showing lesser changes in protein biosynthesis expression. Expression of flagella genes was significantly more inhibited in stationary phase cells of Tennessee than LT2 both before and after desiccation.
Project description:To explore the mechanisms of Salmonella desiccation resistance, we studied the transcriptomic responses in Salmonella Tennessee (Tennessee), using S. Typhimurium LT2 (LT2), a strain weakly resistant to desiccation, as a reference strain. In response to 2 h air-drying at 11% equilibrated relative humidity, approximately one-fourth of the ORFs in the Tennessee genome and one-fifth in LT2 were differentially expressed (> 2-fold). Among all differentially expressed functional groups (>5-fold) in both strains, the expression fold change associated with fatty acid metabolism was the highest, and constituted 51 and 35% of the total expression fold change in Tennessee and LT2, respectively. Tennessee showed greater changes in expression of genes associated with stress response and envelope modification than LT2, while showing lesser changes in protein biosynthesis expression. Expression of flagella genes was significantly more inhibited in stationary phase cells of Tennessee than LT2 both before and after desiccation. Salmonella Typhimurium LT2 ATCC strain 19585 (LT2) and Tennessee strain K4643 (Tennessee) were grown in TSB at 37 M-BM-:C with shaking for 20 h. Cells (~8 log CFU) for each strain were added on the discs and either stored at -80M-BM-:C directly, as control samples; or kept at 11% ERH at 25M-BM-0C for 2 h and then transferred into -80 M-BM-:C, as desiccation treated samples. Three independent experiments were carried out for each condition.
Project description:Salmonella can survive for long periods under extreme desiccation conditions. This stress response poses a risk for food safety, but relatively little is known about the molecular and cellular regulation of this adaptation mechanism. To determine the genetic components involved in Salmonella’s cellular response to desiccation, we performed a global transcriptomic analysis comparing Salmonella Typhimurium cells equilibrated to low water activity (aw 0.11) and cells equilibrated to high water activity (aw 1.0). The analysis revealed that 719 genes were differentially regulated between the two conditions, of which 290 genes were up-regulated at aw 0.11. Most of these genes were involved in metabolic pathways, transporter regulation, DNA replication/repair, transcription and translation, and, more importantly, virulence genes.
Project description:Desiccation tolerance (DT) allowed seed plants to conquer ecosystems with long periods of limited water availability. This adaptive features allows seeds to remain dried for very long times without losing their ability to germinate. There is little information about all the signaling components required to achieve DT and on how transcription factors (TFs) modulate global DT processes. We performed RNA-seq experiment and carbohydrates profiles of lec1, lec2, fus3 and abi3, as well as their corresponding wild types, at three stages of seed development 15, 17 and 21 DAF (day after open flower) belonging to the seed desiccation period. A complex experimental design approach and regulatory networks prediction were used to identify differentially expressed genes specifically involved in DT process. In order to identify mechanisms involved in the acquisition of DT during seed development, we designed a comparative transcriptomic analysis between the seed desiccation intolerant (DI) mutants lec1-1, abi3-5 and fus3-3, the desiccation tolerant mutant lec2-1 and the desiccation tolerant weak allele of abi3 (abi3-1) with their respective wild type controls. This analysis should allow to identify genes that are differentially expressed in the desiccation intolerant mutants respect to tolerant mutants and WT controls.
Project description:This SuperSeries is composed of the following subset Series: GSE12997: Comparative transcriptomic analysis of BA- or BL- associated murine colonic epithelium GSE12998: Comparative transcriptomic analysis of BA- or BL- associated murine colonic epithelium after O157 infection Refer to individual Series
Project description:To identify the mechanisms of the adaptation to terrestrial ecosystems, an RNA-seq based transcriptome analysis was conducted on a desiccation resistant cyanobacterium, Nostoc sp. MG11.
Project description:Climate change is one of the main factors shaping the distribution and biodiversity of organisms, among others by greatly altering water availability, thus exposing species and ecosystems to harsh desiccation conditions. Insects are especially threatened by these challenging dry environments, because of their small size and thus large surface area to volume ratio. Drosophila melanogaster is a great model to study the response of populations to rapidly changing conditions, because of its southern-central African origin and recent worldwide colonization. Desiccation stress response is a complex and extensively studied trait, however the natural variation in tolerance, and the underlying transcriptomic and physiological mechanisms are still not clear. Here we subjected to desiccation stress 74 natural D. melanogaster European strains, belonging to five different climate zones. We found that the strains from cold semi-arid climates are more tolerant compared with the ones from hot summer mediterranean climate zones. Moreover, the variance in the tolerance of the strains correlates with the interaction of altitude and evaporation. We found that the tolerant strains had a lower level of initial water content and lose less water during desiccation stress. The reduction in the water loss is probably due to the decrease in the respiration rate in desiccation stress conditions, and to the cuticular hydrocarbon composition found in tolerant strains. Moreover, we found that the genes related to response to stimulus and environmental sensing are up-regulated only in the tolerant strains. Furthermore, we identified several desiccation candidate genes unique for the tolerant strains that can be targeted by tRNA derived fragments, known to be important in post-transcriptional gene regulation in several stress responses. We also looked for transposable element insertions possibly affecting the expression of genes relevant in desiccation tolerance, however, except for four insertions, there is no clear association between the presence of the TE insertions and the tolerance level of the strains. Overall, our study for the first time described the physiological and transcriptomic changes underlying the desiccation tolerance of natural European D. melanogaster strains and puts tRFs in the scope of desiccation related studies as possible regulators of desiccation tolerance.
Project description:Desiccation tolerance has been implicated as an important characteristic that potentiates the spread of the bacterial pathogen Acinetobacter baumannii through hospitals on dry surfaces. Despite the potential importance of this stress response, scarce information is available describing the underlying mechanisms of A. baumannii desiccation tolerance. Here we characterize the factors influencing desiccation survival of A. baumannii. At the macroscale level, we find that desiccation tolerance is influenced by cell density, growth phase, and desiccation medium. Our transcriptome analysis indicates that desiccation represents a unique state for A. baumannii compared to commonly studied growth conditions and strongly influences pathways responsible for proteostasis. Remarkably, we find that an increase in total cellular protein aggregates, which is often considered deleterious, correlates positively with the ability of A. baumannii to survive desiccation. We show that artificially inducing protein aggregate formation increases desiccation survival, and more importantly, that proteins incorporated into cellular aggregates can retain activity. Our results suggest that protein aggregates may promote desiccation tolerance in A. baumannii through preserving and protecting proteins from damage during desiccation until rehydration occurs.
Project description:Transcriptional profiles of Salmonella Typhimurium str. ST4/74 air-dried onto stainless steel for 4 h was compared to an early stationary phase (ESP) culture control. Cells that had been air-dried for 4 h were then subsequently rehydrated with water for a 30 min period, after which the transcriptional profile was compared to an ESP control. Carried out using 2 biological replicates for each sample; hybridised in a two-channel hybridization against Salmonella genomic DNA as the comparator/reference.