Myxozoans are microscopical parasites widely distributed in fish, with over 2,600 described species, but their actual diversity is still underestimated. Among salmonids, more than 70 myxozoan species have been identified. This study focuses on species of Chloromyxum Mingazzini, 1890 that infect salmonid kidneys, particularly C. majori Yasutake et Wood, 1957 and C. schurovi Shulman et Ieshko, 2003. Despite their similar spore morphology, they exhibit distinct host preferences, tissue affinities and geographical distributions. Chloromyxum schurovi predominantly infects the renal tubules of Salmo salar Linnaues and S. trutta Linnaeus in Europe, while C. majori targets the glomeruli of Oncorhynchus mykiss (Walbaum) and O. tshawytscha (Walbaum) in North America. The sequence data for C. majori and C. schurovi have been either missing or questionable. In our study, we examined the kidneys of two salmonid species for chloromyxid infections, using both morphological and molecular data to characterise Chloromyxum species in salmonids. The sequence of C. schurovi obtained in our study did not match the previously published parasite data. Instead, it clustered as an independent lineage sister to the Paramyxidium Freeman et Kristmundsson, 2018 clade gathering the species from various fish organs, including the urinary tract. Our findings clarified the taxonomic origin of the previous C. schurovi sequence as Myxidium giardi Cépède, 1906, highlighting the risks associated with the presence of myxozoan blood stages in the bloodstream of their fish host and the challenges of non-specific PCR amplification. We redescribe C. schurovi, thus contributing to a better understanding of the diversity and phylogeny of kidney-infecting species of Chloromyxum.
- MeSH
- Phylogeny * MeSH
- Kidney parasitology MeSH
- Myxozoa * classification genetics anatomy & histology isolation & purification MeSH
- Fish Diseases * parasitology MeSH
- Parasitic Diseases, Animal * parasitology epidemiology MeSH
- Trout * parasitology MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
The myxozoan parasite 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, a chronic immunopathology characterized by massive lymphocyte proliferation and hyperplasia, which manifests as swollen kidneys in susceptible hosts. Studying the immune response towards the parasite helps us understand the causes and consequences of PKD. While examining the B cell population during a seasonal outbreak of PKD, we unexpectedly detected the B cell marker immunoglobulin M (IgM) on red blood cells (RBCs) of infected farmed rainbow trout. Here, we studied the nature of this IgM and this IgM+ cell population. We verified the presence of surface IgM via parallel approaches: flow cytometry, microscopy, and mass spectrometry. The levels of surface IgM (allowing complete resolution of IgM- RBCs from IgM+ RBCs) and frequency of IgM+ RBCs (with up to 99% of RBCs being positive) have not been described before in healthy fishes nor those suffering from disease. To assess the influence of the disease on these cells, we profiled the transcriptomes of teleost RBCs in health and disease. Compared to RBCs originating from healthy fish, PKD fundamentally altered RBCs in their metabolism, adhesion, and innate immune response to inflammation. In summary, RBCs play a larger role in host immunity than previously appreciated. Specifically, our findings indicate that the nucleated RBCs of rainbow trout interact with host IgM and contribute to the immune response in PKD.
- MeSH
- B-Lymphocytes MeSH
- Erythrocytes MeSH
- Immunoglobulin M MeSH
- Kidney Diseases * MeSH
- Oncorhynchus mykiss * MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Salmincola markewitschi Shedko et Shedko, 2002 (Copepoda: Lernaeopodidae) is an ectoparasitic copepod mainly infecting the buccal cavities of white-spotted charr Salvelinus leucomaenis (Pallas) (Salmonidae). This species has only been recorded from Northeast Asia, where a morphologically similar congener Salmincola carpionis (Krøyer, 1837) is also distributed, using the same host species. These copepods are hard to distinguish from each other because of their similarities. We thus examined the newly collected specimens morphologically and genetically from five populations of white-spotted charr in Japan. Most of the specimens were morphologically consistent with S. markewitschi but showed great variations in the numbers of spines on the exopods of the antennae, shape of the maxilliped myxal palps, and the bulla diameter. Consequently, some specimens shared characteristics with S. carpionis. In addition to the mophological continuities, genetic analyses of 28S rDNA and COI mitochondrial DNA confirmed that all specimens belong to a single species. Further taxonomic revisions are required to draw conclusions of whether S. markewitschi is a valid species different from S. carpionis, by collecting samples from across their wide distributional ranges, such as Europe, North America, and Northeast Asia. A key to identification of species of Salmincola Wilson, 1915 occurring in Japan is also provided.
- MeSH
- Copepoda * genetics MeSH
- Host Specificity MeSH
- Trout genetics parasitology MeSH
- DNA, Ribosomal MeSH
- Animals MeSH
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- Animals MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Europe MeSH
One of the main contributors to pharmaceutical pollution of surface waters are non-steroidal anti-inflammatory drugs (NSAIDs) that contaminate the food chain and affect non-target water species. As there are not many studies focusing on toxic effects of NSAIDs on freshwater fish species and specially effects after dietary exposure, we selected rainbow trout (Oncorhynchus mykiss) as the ideal model to examine the impact of two NSAIDs - diclofenac (DCF) and ibuprofen (IBP). The aim of our study was to test toxicity of environmentally relevant concentrations of these drugs together with exposure doses of 100× higher, including their mixture; and to deepen knowledge about the mechanism of toxicity of these drugs. This study revealed kidneys as the most affected organ with hyalinosis, an increase in oxidative stress markers, and changes in gene expression of heat shock protein 70 to be signs of renal toxicity. Furthermore, hepatotoxicity was confirmed by histopathological analysis (i.e. dystrophy, congestion, and inflammatory cell increase), change in biochemical markers, increase in heat shock protein 70 mRNA, and by oxidative stress analysis. The gills were locally deformed and showed signs of inflammatory processes and necrotic areas. Given the increase in oxidative stress markers and heat shock protein 70 mRNA, severe impairment of oxygen transport may be one of the toxic pathways of NSAIDs. Regarding the microbiota, an overgrowth of Gram-positive species was detected; in particular, significant dysbiosis in the Fusobacteria/Firmicutes ratio was observed. In conclusion, the changes observed after dietary exposure to NSAIDs can influence the organism homeostasis, induce ROS production, potentiate inflammations, and cause gut dysbiosis. Even the environmentally relevant concentration of NSAIDs pose a risk to the aquatic ecosystem as it changed O. mykiss health parameters and we assume that the toxicity of NSAIDs manifests itself at the level of mitochondria and proteins.
- MeSH
- Anti-Inflammatory Agents, Non-Steroidal metabolism MeSH
- Biomarkers metabolism MeSH
- Water Pollutants, Chemical * metabolism MeSH
- Diclofenac metabolism MeSH
- Dysbiosis MeSH
- Ecosystem MeSH
- Disease Outbreaks MeSH
- Ibuprofen metabolism toxicity MeSH
- Oxygen metabolism MeSH
- Pharmaceutical Preparations metabolism MeSH
- RNA, Messenger metabolism MeSH
- Oncorhynchus mykiss * metabolism MeSH
- Oxidative Stress MeSH
- HSP70 Heat-Shock Proteins metabolism MeSH
- Reactive Oxygen Species metabolism MeSH
- Gastrointestinal Microbiome * MeSH
- Water metabolism MeSH
- Inflammation chemically induced MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
Výskum probiotík pre akvakultúru je v ranom štádiu a pre ich implementáciu je potrebné vykonať ešte množstvo experimentov. Laktiplantibacily patria medzi mikroorganizmy, ktoré sa najčastejšie používajú na prípravu probiotických preparátov. Doterajšie výsledky nie sú postačujúce, práve preto sú potrebné ďalšie štúdie. Výber probiotík pre akvakultúru a ich vývoj pre komerčné využitie v akvakultúre je mnohostupňový a multidisciplinárny proces vyžadujúci si v prvej etape základný a neskôr aj aplikovaný výskum a posúdenie jeho použitia v praxi. Cieľom štúdie bolo pripraviť probiotické krmivo pre ryby s využitím pomocných látok a následne sledovať prežívateľnosť probiotických bakteriálnych buniek v krmive počas 9-mesačného skladovania pri chladničkovej (4 °C) a izbovej teplote (22 °C). Na prípravu krmiva bol použitý kmeň Lactobacillus plantarum R2 Biocenol™ (CCM 8674) (podľa novej taxonómie Lactiplantibacillus plantarum), potenciálne využiteľný pre probiotické účely v akvakultúre. Lepšia prežívateľnosť probiotických bakteriálnych buniek bola zaznamenaná vo vzorkách krmiva A (Aquatex 41 HMD) v porovnaní so vzorkami probiotických peliet B (Inicio 918-2). Keďže oxidácia mastných kyselín v krmive ovplyvňuje nutričnú kvalitu jednotlivých komponentov krmiva, predpokladáme, že vyššie množstvo oleja v krmive B negatívne ovplyvnilo prežívateľnosť probiotických bakteriálnych buniek. Najvyššie počty životaschopných probiotických baktérií boli zaznamenané pri 4 °C skladovania krmiva. Po 9 mesiacoch skladovania pri chladničkovej teplote počty laktiplantibacilov vo vzorkách krmiva A klesli z hodnoty 7,30 log10KTJ/g na počet 5,57 log10KTJ/g. Teplota je považovaná za rozhodujúci faktor ovplyvňujúci životaschopnosť a prežívateľnosť probiotických baktérií počas doby skladovania.
Research in probiotics for aquaculture is at an early stage of development and much work is still needed. Lactiplantibacilli belong to the microorganisms most frequently used to prepare the probiotics. The available information is inconclusive, since few experiments with sufficiently robust design have been conducted to permit critical evaluation. The development of probiotics applicable to commercial use in aquaculture is a multistep and multidisciplinary process requiring both empirical and fundamental research, full-scale trials, and an economic assessment of its use. The aim of the study was to prepare a probiotic aquafeed via excipients and subsequently to observe the survival of probiotic bacterial cells in the feed during the nine months storage period at a refrigerator (4 °C) or room temperature (22 °C). The strain Lactobacillus plantarum R2 Biocenol™ (CCM 8674) (according to the new taxonomy Lactiplantibacillus plantarum), potentially usable as a probiotic in aquaculture, was administered to prepare the aquafeed. Better survival of probiotic bacterial cells was recorded in a samples of pellets A (Aquatex 41 HMD) compared to the samples of probiotic pellets B (Inicio 918-2). Since oxidation of fatty acids in feed affects the nutritional quality of individual feed components, we assume that higher amounts of oil in feed B negatively affected the survival of probiotic bacterial cells. The highest numbers of viable probiotic bacteria cells were recorded at 4 °C storage of probiotic feed samples. The number of lactiplantibacilli dropped from 7.30 log10CFU . g–1 to 5.57 log10CFU . g–1 after the nine months storage period of feed samples A at 4 °C. Temperature is considered as a critical factor influencing probiotic viability and survival during storage period.
The aim of this study was to reveal the effects of foodborne fluoxetine on morphological and condition profile, hematological profile, biochemical and oxidative stress indices on juvenile rainbow trout. The study was performed according to OECD Guideline No. 215. Fluoxetine was incorporated into Biomar 921 pellets at a dose of 0.047 mg/kg (environmental concentration), 0.577 mg/kg and 6.7 mg/kg. There was statistically significant change in hematological profile, including an increasing trend in neutrophil/lymphocyte ratio and a decreasing trend in the number of lymphocytes. Measurements of oxidative stress indicated decreased activity of the detoxifying enzyme glutathione-S-transferase in the liver and kidney. However, the measurement of GR, GPx, CAT, SOD activity, and TBARS showed no changes. Histopathological examination revealed damage to the proximal tubules of caudal kidney in exposed groups. This study confirms that fluoxetine has a significant effect on immune response.
- MeSH
- Antidepressive Agents, Second-Generation toxicity MeSH
- Water Pollutants, Chemical toxicity MeSH
- Fluoxetine toxicity MeSH
- Immunity drug effects MeSH
- Food Contamination MeSH
- Blood Cell Count MeSH
- Animal Feed MeSH
- Oncorhynchus mykiss blood immunology MeSH
- Oxidative Stress drug effects MeSH
- Kidney Tubules, Proximal drug effects MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
Two genotypes of the intestinal parasite Ceratonova shasta infect Oncorhynchus mykiss: genotype 0 results in a chronic infection with low mortality while genotype IIR causes disease with high mortality. We determined parasite load and the relative expression of six immune factors (IgT, IgM, IL-6, IL-8, IL-10, IFNG) in fish infected with either genotype over 29 days post-exposure. In genotype IIR infections the host responded with upregulation of inflammatory and regulatory cytokines. In contrast, genotype 0 infection did not elicit an inflammatory response and expression of IFNG and IL-10 was lower. Antibody expression was upregulated in both infections but appeared to have limited efficacy in the virulent genotype IIR infections. Histologically, in genotype 0 infections the parasite migrated through the tissue layers causing inflammation but minimal damage to the mucosal epithelium, which contrasts with the severe pathology found in genotype IIR infections.
- MeSH
- Cytokines genetics metabolism MeSH
- Genotype * MeSH
- Immunoglobulin M blood MeSH
- Immunoglobulins blood MeSH
- Host-Parasite Interactions MeSH
- Myxozoa genetics pathogenicity MeSH
- Fish Diseases immunology MeSH
- Oncorhynchus mykiss immunology MeSH
- Parasitic Diseases, Animal immunology MeSH
- Parasite Load MeSH
- Cell Movement MeSH
- Fish Proteins blood MeSH
- Mucous Membrane immunology MeSH
- Virulence MeSH
- Inflammation immunology MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, N.I.H., Extramural MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Proliferative kidney disease (PKD) is a widespread temperature-dependent disease in salmonids caused by the myxozoan parasite, Tetracapsuloides bryosalmonae (Canning, Curry, Feist, Longshaw et Okamura, 1999) (Tb). Tb has a two-host life cycle, involving fish as an intermediate host and freshwater bryozoans as the definitive host. Although salmonids are acknowledged as hosts for the parasite, it is less clear which fish species are active hosts in the life cycle of Tb. Differences in infection dynamics have been observed between some fish species, which are thought to be related to the existence of two main Tb-strains, the American and European. Iceland, having three species of indigenous salmonids and positioned geographically between Europe and North America, is an ideal location to study the natural development of Tb in wild fish. The main aim of this study was to determine the genetic origin of Tb in Iceland and confirm whether mature spores are produced in Icelandic salmonids. In this study, Icelandic salmonids were infected with the European Tb-strain. In situ hybridisation revealed that intraluminal sporogonic stages, including mature spores, were commonly observed in all three salmonid species. The presence of intraluminal stages has previously been confirmed in brown trout Salmo trutta Linnaeus and Atlantic salmon S. salar Linnaeus in Europe, but they have only been observed in Arctic charr Salvelinus alpinus (Linnaeus) in North America, infected by the local strain. This is, therefore, the first time that sporogonic stages have been observed in Arctic charr in Europe, where fish are infected with the European Tb-strain. Our data strongly suggest that all the three salmonid species inhabiting Icelandic waters serve as active hosts in the life cycle of Tb. However, for full confirmation, transmission trials are needed.
- MeSH
- In Situ Hybridization veterinary MeSH
- Host-Parasite Interactions * MeSH
- Myxozoa growth & development physiology MeSH
- Fish Diseases parasitology MeSH
- Parasitic Diseases, Animal parasitology MeSH
- Trout * MeSH
- Salmo salar * MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
Due to the fact that plastic pollution is a global environmental problem of modern age, studies on the impact of these synthetic materials on aquatic, and especially fish organisms, are an important part of the ecosystem and human nutrition. In our study, the toxicity of pristine polyethylene (PE) microparticles (approx. 50 μm) on rainbow trout (Oncorhynchus mykiss) was tested in three different dietary concentrations - 0.5%, 2% and 5%. After six weeks of exposure, various health indices were evaluated. Electron microscopy of the intestine revealed the disintegration of PE particles to <5 μm in size, and thus we concluded that microplastics are able to reach tissues. The haematological profile revealed changes in total red blood cells count and haematocrit (5% PE) which could be associated with spleen congestion observed histologically. The marker of lipid peroxidation was increased in gills suggesting the disruption of balance in antioxidant enzymes capacity and histopathological imaging revealed inflammation in higher PE concentrations. In addition, ammonia was decreased and calcium elevated in biochemical profile, confirming the gill damage. Electron microscopy of the gills showed lesions of lamellae and visible rings around the mucinous cell opening indicating their higher activity. Another injured was the liver tissue, as confirmed by hepatodystrophies and increased expression of pro-inflammatory genes in 2% PE. Impaired innate immunity was confirmed by an increased presence of mucinous cells and a decrease in leukocytes. Kidney damage manifested itself by higher expression of pro-inflammatory cytokines and histopathology. The damage in gills, liver and kidney together correlated with the increased antioxidant capacity of plasma. In conclusion, PE microparticles are able to affect health indices of O. mykiss. The potential problem for aquatic ecosystems and even human consumption should be considered.
Piscine cytochrome P450 (CYP) enzymes play an important role in the metabolism of xenobiotics. Xenobiotics often act as inducers of CYP1A1 and CYP3A expression and activity in fish. We compared constitutive mRNA expression of CYP1A1, CYP3A27, and CYP3A45 and catalytic activity of CYP1A (7-ethoxyresorufin-O-deethylation, EROD) and CYP3A-like (benzyloxy-4-trifluoromethylcoumarin-O-debenzyloxylation, BFCOD) enzymes in the following six rainbow trout tissues: liver, gill, heart, brain, intestine, and gonad. mRNA expression and activity were present in all investigated tissues. The CYP1A1 mRNA expression was higher in the liver, gill, heart, and brain compared to gonad and intestine. The intestine was the main site of CYP3A27 and CYP3A45 expression. The highest EROD and BFCOD activity was observed in liver tissue followed in descending order by heart, brain, gill, intestine, and gonad. Such differences might be related to the role of CYP physiological functions in the specific tissue. Rainbow trout exposure to 50 mg/kg of β-naphthoflavone for 48 h resulted in a 7.5- and 5.9-fold increase in liver EROD and BFCOD activity, respectively. In vitro EROD activity inhibition with ellipticine showed tissue-specific inhibition, while ketoconazole decreased BFCOD activity by 50-98 % in all tissues. Further studies are needed to identify all CYP isoforms that are responsible for these activities and modes of regulation.
- MeSH
- Cytochrome P-450 CYP1A1 genetics metabolism MeSH
- Cytochrome P-450 CYP3A genetics metabolism MeSH
- Liver enzymology MeSH
- RNA, Messenger genetics metabolism MeSH
- Brain enzymology MeSH
- Myocardium enzymology MeSH
- Oncorhynchus mykiss metabolism MeSH
- Sex Characteristics MeSH
- Gene Expression Regulation, Enzymologic physiology MeSH
- Intestines enzymology MeSH
- Gills enzymology MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
