Unknown,Transcriptomics,Genomics,Proteomics

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Response of Rhodospirillum rubrum S1H to three pharmaceuticals

ABSTRACT: The present study explores the potential of compound-specific gene-upregulation profiles in the ubiquitous purple nonsulfur bacterium Rhodospirillum rubrum S1H as biomarkers for exposure to surface water contaminants, i.e. high production-volume pharmaceuticals. Even though the pharmaceuticals [i.e., acetylsalicylic acid (ASA), diclofenac (DCF), and 17M-NM-1-ethinylestradiol (EE2)] did not affect the bacterial growth kinetics at environmentally-relevant concentrations (86nM), whole-genome microarray analyses revealed the upregulation of 128, 49, and 47 genes upon exposure to DCF, ASA, and EE2, respectively. A strong overlap (27-48%) was observed between transcriptional responses, but a total of 93 genes were found to be upregulated in a compound-specific manner. Hence, we were able to identify 74 and 15 potential biomarker genes for DCF and ASA, respectively. DCF specifically induced genes involved mainly in stress response, signal transduction, response regulation, the electron transport chain, and transcription, while ASA specifically induced genes predominantly involved in signal transduction, response regulation, and trans-membrane translocation. Moreover, our findings validated triclosan-specific biomarker genes that were identified previously. As only 4 genes were specifically-upregulated for EE2, no representative biomarker profile was identified. This study illustrates that a pollutant-specific molecular response can be generated in R. rubrum S1H, which could become a relevant model-microorganism to screen for the ecological impact of surface water contaminants in situ. KEYWORDS: environmental impact studies, risk assessment, biosensor, wastewater, micropollutant, aspirin Two-condition experiments. Comparing samples after induction of three pharmaceuticals each with a non-induced samples. Biological triplicate. Each array contains 3 technical replicates.

ORGANISM(S): Rhodospirillum rubrum

SUBMITTER: Pieter Monsieurs

PROVIDER: E-GEOD-23794 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Aiming at the development of a micropollutant biosensor in the frame of the Micro-Ecological Life Support System Alternative (MELiSSA), a pilot study was initiated to identify triclosan (TCS)-responsive biomarker genes in the MELiSSA carbon-mineralizing microorganism, Rhodospirillum rubrum S1H. TCS is a biocide, commonly found in human excrements and is considered an emerging pollutant in wastewater and the environment. Chronic exposure to MELiSSA-relevant concentrations (≥25 µg L-1) TCS caused a significant extension of the lag phase without affecting the growth rate. Analytical determination gave no indication of TCS biodegradation during the growth experiment and flow cytometric viability analyses revealed that TCS is only slightly toxic to R. rubrum. Through microarray analyses, the genetic mechanisms supporting the reversibility of TCS-induced inhibition were scrutinized. Hence, an extremely TCS-responsive cluster of four small adjacent genes was revealed, with up to 34-fold induction at 25 µg L-1. These four genes, for which the name micropollutant-upregulated factor (muf) was proposed; appear to be unique to R. rubrum and are shown for the first time to be involved in the response to stress. Moreover, numerous other systems that are associated with the proton-motive force were shown to be responsive to TCS, but never as highly upregulated as the muf genes. Hence, R. rubrum induced the phage shock protein operon (pspABC), numerous major facilitator efflux systems, cell envelope consolidation mechanisms, oxidative stress response, beta-oxidation, and carbonic anhydrase; while downregulating bacterial conjugation- and carboxysome synthesis genes. The muf genes and three efflux-related genes showed most potential as low-dose biomarkers. The two microarray experiments (10 and 25 µg l-1 Triclosan) were all performed in biological triplicate and containing three (in-slide) technical repeats. For all conditions, the Triclosan exposed sample (Cy5) was compared with the non-exposed solvent control (Cy3) to identify those genes that were differentially expressed upon Triclosan exposure.

Project description:The objective of this study was to gain mechanistic insight into how mummichog are able to produce eggs during exposures to high levels of EE2. Mummichog were exposed to 0, 50 or 250 ng/L of EE2 for 14 d. A mummichog microarray was used to identify genomic responses associated with high EE2 exposure, and effects of EE2 on target genes involved in lipid mobilization and transport and steroidogenesis, two important (EE2 regulated) pathways involved in egg production, were measured using real-time PCR. In addition, changes at higher level biological endpoints such as plasma steroid production and gonad morphology were measured to examine downstream responses to EE2. There were no differences in gonadosomatic index, liversomatic index, gonad development, or plasma estradiol levels after exposure to EE2, although testosterone decreased with EE2 exposures. Similar to other species, mummichog showed alterations to plasma steroid levels, and similar processes at the molecular level were identified as being altered by EE2, including cell processes associated with lipids. However, unlike other species, mummichog showed no differences in GSI or ovarian development. Fatty acids were affected at both the transcript and translation level, which suggests they are a major target of estrogens. Lipids are important for both growth and reproduction, and provide oocytes with nutrients. Interestingly, mummichog showed no effect on apolipoprotein expression, which is important in lipid transport. Therefore, it is hypothesized that mummichog are normally able to transport lipids for energy and nutrients to the ovary, while this is affected in other species. Novel gene regulatory networks for protein modification targets were also constructed to learn more about the potential roles of estrogens in the teleost liver. Although post-translational modifications (PTMs) are important regulatory mechanisms, the roles of PTMs in protein regulation in fish and the susceptibility of PTMs to aquatic pollutants are largely unexplored and may offer novel insight into mechanisms of endocrine disruption. Mummichog were exposed to 0, 50, and 250 ng/L EE2 for 14 days. Microarray analysis was performed with five biological replicated (5 control, 5 EE2 50 ng/L, 5 EE2 250 ng/L). Female liver tissue was used for the analysis.

Project description:17alpha-ethinylestradiol (EE2) is one of the most potent estrogens that have the ability to interfere with the endocrine system of fish. The objective was to investigate the effects and mechanisms of action caused by 60 days of dietary exposure to 0.2 mg EE2/kg and 0.07 mg EE2/kg feed in female largemouth bass (LMB) during the reproductive season. Microarrays and pathway analyses were performed on hepatic tissues to identify genes and biological processes altered in female LMB by EE2 exposure. The hypothesis was that the two concentrations of EE2 would produce dose-response changes in sensitive genes. Body and ovary weights were measured and blood was collected for measurement of plasma steroid hormones (17beta-estradiol (E2), testosterone (T)) and vitellogenin (VTG) using ELISA. The 0.2 mg EE2/kg feed exposure reduced the gonadosomatic index (GSI) by 75%, and plasma levels of E2 and T were reduced by over 90%. Plasma VTG was increased by approximately 100% (from 4 to 8mg/ml) by the 0.2 mg/kg treatment. T levels, from the 0.07 mg EE2/kg feed, reduced GSI by approximately 30% and circulating E2 and T by ~80% but did not affect VTG concentrations. We found 1,594 and 1,165 genes were significantly affected (p<0.05) by the 0.07 mg EE2/kg feed and 0.2 mg EE2/kg feed, respectively. Gene ontology (GO) analysis revealed that there were different biological processes regulated by the two concentrations of EE2. Pathway analysis showed that the 0.07 mg EE2/kg feed exposure caused differential regulation of genes associated with fatty acid biosynthesis and glycolysis, indicating some metabolic effects. In contrast, the 0.2 mg EE2/kg feed exposure altered transcription of genes involved in immune response and apoptosis, suggesting a toxic response at this concentration. These results suggest that the two concentrations demonstrated distinct physiological responses, with the higher concentration inducing complete endocrine disruption in LMB. These findings demonstrate the usefulness of microarrays to identify possible biomarkers and modes of toxic action to dietary exposure in LMB. Two concentrations of EE2 would produce dose-response changes in sensitive genes. Female LMB were fed 5 days per week for 60 days with floating pellets that contained 0.07 or 0.2 mg/kg of EE2.

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Response of Rhodospirillum rubrum S1H to three pharmaceuticals

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