Project description:The myxozoan Tetracapsuloides bryosalmonae is the causative agent of proliferative kidney disease (PKD) – a disease of salmonid fishes, notably of the commercially farmed rainbow trout Oncorhynchus mykiss. Both wild and farmed salmonids are threatened by this virulent/deadly disease, which is often expressed by swollen kidneys. In order to understand the causes and consequences of the disease, we studied the immune response towards the parasite. To profile the influence of the disease on these cells, we produced a transcriptome of teleost RBCs in health and disease. Compared to erythrocytes originating from healthy fish, PKD fundamentally altered RBCs in their metabolism, adhesion, and response to inflammation.
Project description:The regulatory system of erythropoiesis through erythropoietin (EPO) and its receptor (EPOR) is essential for vertebrates' life. In humans, EPO affects the erythroid progenitors and stimulates proliferation and differentiation. The EPO-EPOR axis is mainly mediated by the JAK2-STAT5 pathway. After terminal maturation, erythrocytes lost EPOR expression; however, erythrocytes of amphibian Xenopus tropicalis maintain EPOR expression even after their terminal maturation. Because erythrocytes of vertebrates except for adult mammals are nucleated, we hypothesized that EPO can alter its transcriptional state. To explore the effects of EPO on Xenopus mature erythrocytes, we performed RNA-Seq analysis on EPO-stimulated Xenopus peripheral blood cells. The EPO-stimulated group showed increased expression of direct target genes of STAT such as cish, socs3, and socs1 indicating a functional signal transduction system. Furthermore, we observed several EPO-responsive genes that were not reported in mammalian erythroid progenitors. These findings suggest the functional difference between enucleated erythrocytes in adult mammals and nucleated erythrocytes in fetal mammals and non-mammalian vertebrates.
Project description:The pollution of the environment with microplastics has been recognized as an emerging threat worldwide. Due to an exponential increase in production of plastic over the last eight decades and its longevity in the environment, accumulating amounts of microplastic are polluting rivers, lakes and the ocean. Their entry pathways are diverse and still only incompletely understood. Since microplastics are usually defined smaller than 5 mm, it can be ingested by a wide range of aquatic organisms including teleost fish. There are different approaches to study the detrimental effects of pollutants on aquatic organisms. On the one hand, generic baseline parameters such as growth and mortality are regularly considered, often accompanied by established stress parameters such as cortisol, heat shock proteins or lipid oxidation. The conflicting findings to date suggest that these parameters might not be sensitive enough to indicate the physiological effects of environmentally relevant microplastic concentrations. For this reason, more sophisticated biological approaches could provide new insights into whether and how microplastics harm fish. To date, proteomic approaches have been used only sporadically when investigating the effects of microplastic exposure on aquatic organisms. So far, this approach has not been used to address potential microplastic impacts in fish. In the present study, a proteomic approach was trialed alongside established methods in an investigation of fish experiencing long-term exposure to environmentally relevant concentrations of microplastics. Two groups of rainbow trout (Oncorhynchus mykiss were exposed to microplastic concentrations and sizes currently encountered in wild fish and an increased concentration, expected to occur in the near future. These groups where compared to a control group maintained in MP free conditions. Five fish of each treatment were sampled at three time points (week 1, week 4, week 17). The experiments were performed in triplicates, resulting in 45 samples used in the proteomic analysis.
Project description:Migratory species experience morphological and physiological changes during transitions between different life stages. In particular, modification of sensory systems is critical for animals to adapt to new environments. For example, to prepare for entry into seawater, salmonids undergo smoltification with dramatic changes in ultraviolet photoreceptors and polarized vision, which are important for orientation and foraging behaviours. Extraretinal organs are also involved in photoreception; however, the ontogenetic development of extraretinal photoreceptors is not well known, especially in migratory species. Here, we investigated whether rainbow trout dermal photoreceptors, melanophores, undergo change in spectral sensitivity during smoltification and which candidate molecules may account for this ontogenetic alteration. Our results showed that, contrary to parr melanophores which are insensitive to light, smolt melanophores displayed chromatic photoresponses with the emergence of cryptochrome and melanopsin expression. We suggest that these modifications may benefit the active foraging behaviour of smolts and enable adaptation to variable environments.
Project description:Diverse animals use Earth's magnetic field in orientation and navigation, but little is known about the molecular mechanisms that underlie magnetoreception. Recent studies have focused on two possibilities: (i) magnetite-based receptors; and (ii) biochemical reactions involving radical pairs. We used RNA sequencing to examine gene expression in the brain of rainbow trout (Oncorhynchus mykiss) after exposure to a magnetic pulse known to disrupt magnetic orientation behaviour. We identified 181 differentially expressed genes, including increased expression of six copies of the frim gene, which encodes a subunit of the universal iron-binding and trafficking protein ferritin. Functions linked to the oxidative effects of free iron (e.g. oxidoreductase activity, transition metal ion binding, mitochondrial oxidative phosphorylation) were also affected. These results are consistent with the hypothesis that a magnetic pulse alters or damages magnetite-based receptors and/or other iron-containing structures, which are subsequently repaired or replaced through processes involving ferritin. Additionally, some genes that function in the development and repair of photoreceptive structures (e.g. crggm3, purp, prl, gcip, crabp1 and pax6) were also differentially expressed, raising the possibility that a magnetic pulse might affect structures and processes unrelated to magnetite-based magnetoreceptors.