Project description:This study aims to understand the molecular adaptation mechanisms of fish gills to environmental Ca2+ changes. Using SuperSAGE, we compared the gene expression profiles of T. nigroviridis gills transferred from natural brackish water (10 ppt salinity,2.9 mM Ca2+) to artificial brackish water with control (2.9 mM), low (0.01 mM) or high (10 mM) Ca2+ concentrations for 2 or 12h.
Project description:we used next-generation sequencing technology to characterise mRNA-seq of brackish water (BW, 10‰), fresh water (FW, 0‰), and sea water (SW, 25‰)-treated Anguilla marmorata's gill, kidney and intestine to elucidate the molecular mechanisms of salinity adaptation.
Project description:Recirculation systems (RAS), which reduce water consumption and improve pathogen control are increasingly used in Atlantic salmon aquaculture. Performance and adaptation of fish to new farming environment is actively investigated. Here, responses to crowding stress were compared in salmon reared in two systems (RAS with brackish water and flowthrough with full salinity water) at low and high density.
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:Aedes aegypti, the principle global vector of arboviral diseases, has been widely regarded to only lay eggs and undergo preimaginal development in fresh water collections. Recent observations however show that it has adapted to develop in anthropogenic brackish water habitats of up to 50% sea water in coastal areas in different continents. This adaptation is characterised by greater salinity tolerance in adult oviposition preference, larvae and changes in sizes of anal papillae. The physiological basis for salinity tolerance in either Ae. aegypti or any of the known salinity-tolerant species of Anopheles malaria vectors is not established. To address this knowledge gap which is of fundamental biological interest and important for control of major diseases we performed RNAseq analysis of gut, anal papillae, and rest of the carcass of Ae. aegypti collected in the field from brackish water (BW) and fresh water habitats (FW) and then maintained as laboratory colonies in BW and FW respectively. We also examined the cuticle structure of larvae, pupae and adult BW and FW Ae. aegypti by microscopy and performed proteomic analysis of the shed cuticles of fourth instar larvae (L4) when they transformed into pupae. The results show that major changes in cuticle structure and composition characterize, and may be the principal factor that permits, the adaptation of Ae. aegypti to brackish water.
Project description:Arthrobacter chlorophenolicus A6 is a 4-chlorophenol degrading soil bacterium with high phyllosphere colonization capacity. Till now the genetic basis for the phyllosphere competency of Arthrobacter or other pollutant-degrading bacteria is uncertain. We investigated global gene expression profile of A. chlorophenolicus grown in the phyllosphere of common bean (Phaseolus vulgaris) compared to growth on agar surfaces. We designed transcriptome arrays and investigated which genes had different transcript levels in the phyllosphere of common bean (Phaseolus vulgaris) as compared to agar surfaces. Since water availability is considered an important factor in phyllosphere survival and activity, we included both high and low relative humidity treatments for the phyllosphere-grown cells. In addition, we determined the expression profile under pollutant exposure by the inclusion of two agar surface treatments, i.e. with and without 4-chlorophenol.