Project description:Ayu (Plecoglossus altivelis), an amphidromous fish distributed in East Asia, live in brackish water (BW) during the larval stage and in fresh water (FW) during the adult stage. In this study, we found that ayu larvae of FW acclimation exhibited a slower growth ratio compared with BW acclimation. However, the mechanism underlying FW acclimation on growth suppression is less known. We employed transcriptome analysis to investigate the differential gene expression of FW acclimation by RNA sequencing. We identified 158 up-regulated and 139 down-regulated transcripts in FW acclimated ayu larvae compared with BW acclimated ones. As determined by Gene Ontology annotation and Kyoto Encyclopedia of Genes and Genomes pathway mapping, functional annotation of the genes covered diverse biological functions and processes. They were involved in in neuroendocrinology, osmotic regulation, energy metabolism, and the cytoskeleton. Transcriptional expression of several differentially expressed genes in response to FW acclimation was further confirmed by real-time quantitative PCR. In accordance with the transcriptome analysis, iodothyronine deiodinase (ID), pro-opiomelanocortin (POMC), betaine--homocysteine S-methyltransferase 1 (BHMT), fructose-bisphosphate aldolase B (aldolase B), tyrosine aminotransferase (TAT), and Na+-K+ ATPase (NKA) were up-regulated after FW acclimation. Furthermore, the mRNA expressions of b-type natriuretic peptide (BNP) and transgelin were down-regulated after FW acclimation. In conclusion, our data indicate that FW acclimation reduces the growth rate of ayu larvae, which may result from the expression alteration of genes related to endocrine hormones, energy metabolism, and direct osmoregulation.
Project description:Recently a Bacillus sp. strain FW 1 was isolated from biogas digestate and shown to have novel resistance to meropenem (MEM), of critical importance in human medicine. MEM-resistance has so far only been described for one species within the genus Bacillus, that is, Bacillus cereus. Bacillus is an abundant representative of the microbial community in biogas digesters and consequently, the finding indicates a risk of spreading such resistance when using the digestate as fertiliser. In this study, the Bacillus strain was characterised and classified as Heyndrickxia oleronia (previous Bacillus oleronius), previously not described to harbour MEM-resistance. The mechanism of resistance was explored by metallo-β-lactamase (MBL) production, mapping of carbapenemase genes and genome analysis. The transferability of MEM-resistance in strain FW 1 was investigated by plasmid transformation/conjugation, combined with genome analysis. The results confirmed MBL production for both strain FW 1 and the type strain H. oleronia DSM 9356T . However, elevated MEM resistance was found for strain FW 1, which was suggested to be caused by the production of unclassified carbapenemase, or overexpression of MBL. Moreover, the results suggest that the MEM-resistance of strain FW 1 is not transferable, thus representing a limited risk of MEM-resistance spread to the environment when using digestate on arable land.
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:The aim of this experiment was to explore transcriptomic changes in the gills of Altantic salmon (Salmo salar) following a model lab based parr smolt transformation from fresh water (FW) to salt water (SW). The process of smoltification (migration from FW to SW) is stimulated by long day photoperiod, which acts on the tissue-specific levels of active thyroid hormone (triiodothyronine, T3) through the expression of thyroid hormone type 2 deiodinase (dio2), responsible for conversion of inactive thyroxine (T4) to T3. To gain insight into the functional significance of dio2 induction, we performed a SW-challenge experiment in which we inhibited dio2 activity by addition of iopanoic acid (IOP) to the SW. We also assessed the ability of co-treatment with T3 to override IOP effects. Juvenile fish maintained in FW were subjected to a standard smolt photoperiod regime known to stimulate smoltification, after which they were randomly allocated to one of the four treatments: SW, SW+IOP, SW+IOP+T3 and FW as a control. Fish (n = 8-10 per treatment) were exposed to these conditions for 6 h and then sacrificed to obtain gill tissue for microarray analysis, carried out using a custom-designed Agilent oligonucleotide microarray platform Salar_2 (one glass slide with 4 x 44K arrays, Agilent design ID: 025520, array design A-MEXP-2065), developed and validated for Atlantic salmon (for details, see specific protocols) . In total, 36 hybridisations were performed on gills from individual fish, with 8-10 replicate fish per treatment. We identified 1939 genes whose expression was significantly increased or decreased by transfer from FW to SW. For a subset of 259 genes, this SW response was abolished if IOP was added to the SW, but maintained if T3 was also present during IOP treatment. This group of genes constitutes a candidate list, for which SW-inducibility appears to be dependent on locally mediated changes in gill T3 availability. The results of this experiment have been submitted for publication in Current Biology and are currently under review.