Project description:A global, systems-based study of the transcriptome response of three drought resistant durum wheat genotypes to water stress. Two parents of a mapping population (Lahn x Cham 1) and a recombinant inbred line (RIL2219), selected for their drought resistance in multiyear field trials, were subjected to controlled time series water stress and samples taken over a six day period to study flag leaf gene expression in parallel with physiological measurements. The aim was to dissect the responses to water stress in an attempt to identify molecular and physiological properties defining stress resistance and thus to build knowledge to accelerate the breeding effort.
Project description:In a previous study we adopted an integrated transcriptomic and proteomic approach to determine the physiological response of E. coli O157:H7 Sakai during exponential phase growth under steady-state conditions relevant to low temperature and water activity conditions experienced during meat carcass chilling in cold air (Kocharunchitt et al., 2012). The findings of that study provide a baseline of knowledge of the physiology of this pathogen, with the response of E. coli O157:H7 to steady-state conditions of cold and osmotic stress. To provide an insight into the genetic systems enabling this organism to adapt to growth at low water activity, we extended the aforementioned study to investigate the growth kinetics of E. coli O157:H7 Sakai during abrupt water activity downshift from 0.993 to 0.967 and, examined time-dependent global alterations in its genome expression upon water activity downshift from 0.993 to 0.967. The genome-wide expression response of E. coli was analysed by both cDNA microarray (transcriptome response) and 2D-LC/MS/MS analysis (proteome response). Differences in gene and protein expression patterns in E. coli before and after water activity downshift were analysed through quantitative and comparative analysis of time series changes in both mRNA and proteins levels.
Project description:Surviving the nutrient-poor aquatic environment for extended periods of time is important for transmission of various water-borne pathogen to the host, including Legionella pneumophila (Lp). Lp is a leading cause of community-acquired and nosocomial pneumonia called Legionnaires’ disease. The remarkable ability of the bacterium to survive in water for periods ranging from several months to years under starvation conditions alludes to regulatory pathways that mediate adaptation to the water environment. In the present study, we investigated a potential role for the LetA/LetS signal transduction system in the successful survival of Lp in water. During infection of host cells, the LetA/LetS two-component system controls the transition from the replicative phase to the transmissive phase in response to nutrient deprivation. In accordance with previous work, the letS mutant used in the present study is defective for pigment production and contributed to cell size reduction in the post-exponential phase. LetS also contributed to cell size reduction when Lp was exposed to water. Importantly, absence of the sensor kinase resulted in a significantly lower survival rate in water at various temperatures, as well as an increase sensitivity to heat shock. Transcriptomic analysis indicated that a general transcriptomic downshift of major pathways is orchestrated by LetA/LetS upon water exposure leading to better survival, suggesting a potential link with the stringent response. However, the expression of the LetA/S regulated small regulatory RNAs RsmY and RsmZ was not changed in a relAspoT mutant, which indicates that the stringent response and the LetA/S response are two distinct regulatory systems important for the survival of Lp in water.
Project description:Legionella pneumophila (Lp) is an opportunistic pathogen and its survival in water is critical for human infection. Therefore, identifying the genes of Lp that are required for survival in water may help devise strategies to prevent Legionella outbreaks. In this study, we exposed Lp in rich medium and in an artificial freshwater medium (Fraquil) for 2, 6 and 24 hours to uncover the global transcriptomic changes of Lp in water. The repression of major metabolic pathways, such as division, transcription and translation, suggests that Lp enters a dormant state in water. The induction of the flagellar associated genes (flg, fli and mot), enhance entry genes (enh) and some Icm/Dot effectors suggests that Lp may be waiting to establish intracellular replication in suitable host. Moreover, many genes involved in resistance to antibiotic and oxidative stress were induced, suggesting that Lp may be more tolerant to environmental stresses in water. Indeed, Lp exposed to water is more resistant to erythromycin, gentamycin and kanamycin than those cultured in rich medium. Apart from this, the gene bdhA involved in the degradation of the intracellular energy storage compound poly-hydroxybutyrate is highly expressed in water. Further characterization shows that bdhA is positively regulated by RpoS during short-term exposure to water. The deletion mutant of bdhA had a survival defect in water at 37°C, demonstrating that this gene is important for maintaining the long-term survivorship of Lp in water. Other identified genes highly induced upon exposure to water could also be necessary for Lp to survive in water.
Project description:Increased oxidative stress induces impairment of the antioxidant defense systems and defects in regeneration of injured tissues. We aim to evaluate the effects of antioxidant bioactive ceramic water (JJ101) on tissue repairing and anti-aging. In vitro, myogenic and antioxidant factors were determined in satellite cells cultured in JJ101 media. Satellite cells grown in JJ101 medium displayed increased expression of Notch1, Pax7, AMP-activating protein kinase-alpha (AMPK-alpha) and anti-oxidant enzymes and significant protection against hydrogen peroxide-induced cell death. In vivo, JJ101 enhanced muscle regeneration via increased number of regenerating muscle fibers and reduced muscle fibrosis. The lifespan in SMP30 KO mice fed with a VC-deficient diet was extended by drinking JJ101. Moreover, the hepatic expression of AMPK-α in JJ101-fed SMP30 KO mice was comparable to that of VC-fed SMP30 KO mice, whereas it was suppressed in tap water-fed SMP30 KO mice. These results suggest that bioactive ceramic water improves antioxidant status through up-regulating antioxidant enzymes and AMPK and thereby provides a favorable niche for satellite cells, leading to an increase in muscle regeneration and compensates oxidative stress.