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Changes in global gene expression of Vibrio parahaemolyticus induced by cold- and heat-stress

ABSTRACT: Vibrio (V.) parahaemolyticus is the leading cause of seafood borne gastro-intestinal infections in humans worldwide. It is widely found in marine environments and is isolated frequently from seawater, estuarine waters, sediments and raw or insufficiently cooked seafood. Within the food chain, V. parahaemolyticus encounters different temperature conditions that might alter the metabolism and pathogenicity of the bacterium. In this study, we performed gene expression profiling of V. parahaemolyticus RIMD 2210633 after exposure to 4°C, 15°C, 20°C, 37°C and 42°C to describe the cold and heat shock response. Analysis of transcriptomics data resulted in differential expression of 19 genes at 20°C, 193 genes at 4°C, 625 genes at 42°C and 639 genes at 15°C. Thus the highest portion of significantly expressed genes was observed at 15°C and 42°C with 13.3% and 13%, respectively. Genes of many functional categories were highly regulated even at lower temperatures. Our results showed that virulence associated genes (tdh1, tdh2, toxR, toxS, vopC, T6SS1, T6SS2) remained largely unaffected by heat or cold stresses. Along with folding and temperature shock depending systems, an overall temperature depended regulation of expression could be shown. Particularly the energy metabolism was affected most by changed temperatures. Whole-genome gene expression studies of food related pathogens such as V. parahaemolyticus reveal how these pathogens react to stress impacts for prediction of its behaviour under conditions like storage and transport.

ORGANISM(S): Vibrio parahaemolyticus RIMD 2210633

PROVIDER: GSE60815 | GEO | 2014/08/27

SECONDARY ACCESSION(S): PRJNA259606

REPOSITORIES: GEO

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Project description:Purpose: We aimed at i) obtaining insight into how a thermophile organism reacts to cold stress, and ii) evaluating the impact of HGT candidates on the acclimation process to temperature decrease. Methods: The experimental design followed a temperature shift timeline: after two weeks of cultivation at 42°C, constant illumination (90 μE) and constant shaking (160 rpm) in photoautotrophic conditions the first sampling took place (Hot_T48_1) and the cultures of G.sulphuraria were swiftly moved to 28°C ( = cold temperature). "Cold" samples were taken after 3h (Cold_T3_2), 12h (Cold_T12_3) and 48h (Cold_T48_4). After cold treatment at 28°C for 48 hours, the G. sulphuraria was then switched to 46°C for 48 hours (="Hot"). Again, samples were taken after 3h (Hot_T3_5), 12h (Hot_T12_6) and 48h (Hot_T48_7). Altogether, a 48h temperature timeshift at 28°C and successive recovery at 46°C were targeted for sampling. Results: Galdieria sulphuraria is a unicellular red alga that lives in hot, acidic, toxic metal-rich, volcanic environments, where few other organisms survive. Its genome harbours up to 5% of genes most likely acquired through horizontal gene transfer. These genes probably contributed to G. sulphuraria’s adaptation to its extreme habitats, resulting in today’s polyextremophilic traits. Here, we applied RNA-sequencing to obtain insights into the acclimation of a thermophilic organism towards temperatures below its growth optimum and to study how horizontally acquired genes contribute to cold acclimation. A decrease in growth temperature from 42 °C/46 °C to 28 °C resulted in an upregulation of ribosome biosynthesis, while excreted proteins, probably components of the cell wall, were downregulated. Photosynthesis was suppressed at cold temperatures, and transcript abundances indicated that C-metabolism switched from gluconeogenesis to glycogen degradation. Folate cycle and S-adenosylmethionine cycle (one-carbon metabolism) were transcriptionally upregulated, probably to drive the biosynthesis of betaine. All these cold-induced changes in gene expression were reversible upon temperature increase. Numerous genes acquired by horizontal gene transfer displayed pronounced temperature-dependent expression changes, corroborating the view that these genes contributed to adaptive evolution in G. sulphuraria.

Project description:Profound understanding of the mechanisms foodborne pathogenic bacteria utilize in adaptation to the environmental stress they encounter during food processing and storage is of paramount importance in design of control measures. Chill temperature is a central control measure applied in minimally processed foods; however, data on the mechanisms the foodborne pathogen Clostridium botulinum activates upon cold stress are scarce. Global gene expression analysis on the C.M-BM- botulinum ATCC 3502 strain upon temperature downshift from 37 M-BM-0C to 15M-BM- M-BM-0C was performed to identify the cold-responsive gene set of this organism. Significant up- or down-regulation of 16 and 11 genes, respectively, was observed already 1 h after the cold shock. At 5 h after the temperature downshift, 199 and 210 genes were up- and down-regulated, respectively. Thus, the cold shock rapidly affected the expression of a gene set of a relatively small size, indicating a targeted acute response to cold shock, whereas extensive metabolic remodeling took place after prolonged exposure to cold. Induction of genes related to fatty acid biosynthesis, oxidative stress response, and iron uptake and storage was observed, in addition to mechanisms previously characterized as cold-tolerance related in bacteria. Furthermore, induction of several uncharacterized DNA-binding transcriptional regulator-encoding genes was observed, suggesting involvement of novel regulatory mechanisms in the cold shock response of C.M-BM- botulinum. The role of such regulatory proteins, CBO0477 and CBO0558A, in cold tolerance of C.M-BM- botulinum ATCC 3502 was demonstrated by the deteriorated growth of mutants of the respective genes at 17M-BM- M-BM-0C. C. botulinum ATCC 3502 wild type cold-shocked vs. pre-cold-shock; 3 replicates; growth at 37C in TPGY broth batch culture and subjected to cold shock to 15C; sampling at mid-log growth phase before cold shock, and 1 h and 5 h after temperature downshift to 15C (= 3 time points). Dye-swapped hybridization.

Project description:We combined heritability analysis of larval development rate with a global expression analysis of this phenotype to investigate genotype by environment interactions across three ecologically relevant temperatures in the Glanville fritillary butterfly (Melitaea cinxia). We focused upon the development of final instar caterpillars which is greatly affected by temperature, and during this stage the caterpillars build up most of the resources for adult life. Second generation, lab reared larvae, initially collected from the Åland metapopulation, were reared in standard lab condition until 6th larval instar. At the beginning of the final (7th) instar stage the larvae were separated into of three temperature conditions: Cold treatment (temperature profile: 8°C 18:00-9:59, 14°C 10:00-11:59, 20°C 12:00-15:59 and 14°C 16:00-17:59) Standard treatment (temperature profile: 15°C 17:00-6:59, 18°C 7:00-8:59, 22°C 9:00-10:59 and 26°C 11:00-16:59) Hot treatment (temperature profile: 8°C 20:00-7:59, 15°C 8:00-9:59, 35°C 10:00-17:59 and 15°C 18:00-19:59) The temperature profiles mimic the diurnal thermal variation of the natural habitat (Åland islands) of samples. Cold treatment mimics a cool and cloudy summer, Standard represents an average temperature profile in the Åland islands and Hot treatment mimics an exceptionally hot and sunny summer, with cold night-time temperatures. The experiment contained several larval families (full-sib) of which three were selected for gene expression analysis. Samples were snap-frozen in liquid nitrogen during mid-development (after 6, 5 and 4 days, for Cold, Standard and Hot respectively). Additional larvae from the same treatments were assayed for survival and growth. Gene expression was analyzed using a mixed model approach to identify genes with potential heritable expression variation (variation among families), genes with plastic expression responses (treatment induced changes) and genes with treatment dependent expression that varies among families (family by treatment interactions).

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Changes in global gene expression of Vibrio parahaemolyticus induced by cold- and heat-stress

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