Myxozoa

SUMMARYIn order to study the infection dynamics of 2 renal myxozoans, Zschokkella hildae Auerbach, 1910 and Gadimyxa atlanticaKøie, Karlsbakk and Nylund, 2007 in cultured Atlantic cod, Gadus morhua L. aged 3–19 months, a specific single-round PCR assay and a double-label in situ hybridization protocol were developed. The results demonstrated that the 2 myxozoans show spatial separation of their development with regard to spore formation inside the renal tubules versus the collecting ducts and ureters, as well as temporal separation with Z. hildae proliferating and developing spores only once the G. atlantica infection decreases, despite the presence of both myxozoans in the smallest fry studied. These results strongly suggest within-host competition of the 2 myxozoans with potential suppression of Z. hildae by G. atlantica until G. morhua acquires immunity against G. atlantica. The quantification of the G. atlantica infection inside the renal tubules before and after a 29-day experi...

Cnidaria, the sister group to Bilateria, is a highly diverse group of animals in terms of morphology, lifecycles, ecology, and development. How this diversity originated and evolved is not well understood because phylogenetic relationships among major cnidarian lineages are unclear, and recent studies present contrasting phylogenetic hypotheses. Here, we use transcriptome data from 15 newly-sequenced species in combination with 26 publicly available genomes and transcriptomes to assess phylogenetic relationships among major cnidarian lineages. Phylogenetic analyses using different partition schemes and models of molecular evolution, as well as topology tests for alternative phylogenetic relationships, support the monophyly of Medusozoa, Anthozoa, Octocorallia, Hydrozoa, and a clade consisting of Staurozoa, Cubozoa, and Scyphozoa. Support for the monophyly of Hexacorallia is weak due to the equivocal position of Ceriantharia. Taken together, these results further resolve deep cnidari...

During a survey of myxosporean parasites of freshwater fishes in Meerut, Uttar Pradesh (UP), India, spores of Henneguya chaudhuryi (Bajpai & Haldar, 1982) were found in the gill lamellae of the spotted snakehead fish Channa punctata (Bloch) (Perciformes: Channidae). This species was described lacking several characteristics in the original description, which makes challenging the accurate diagnosis. Here, we supplemented its description based on morphological, histological and molecular data. Plasmodia of H. chaudhuryi are oval, measuring 60-100 × 40-68 µm, located intralamellarly. Mature spores are elongate, measuring 10.5-13.2 × 3.6-4.2 µm, with two slightly unequal polar capsules with 6-7 filamental turns and two straight, equal caudal appendages, 10-17 µm long. Scanning electron microscopy revealed a flat surface. The 18S rDNA sequence for H. chaudhuryi did not show a close relationship with those of any other Henneguya spp., represented in the GenBank.

SUMMARYThe freshwater bryozoan, Fredericella sultana, is the main primary host of the myxozoan endoparasite, Tetracapsuloides bryosalmonae which causes proliferative kidney disease (PKD) of salmonid fish. Because spores that develop in bryozoan colonies are infectious to fish, bryozoans represent the ultimate source of PKD. Bryozoans produce numerous seed-like dormant stages called statoblasts that enable persistence during unfavourable conditions and achieve long-distance dispersal. The possibility that T. bryosalmonae may undergo vertical transmission via infection of statoblasts has been the subject of much speculation since this is observed in close relatives. This study provides the first evidence that such vertical transmission of T. bryosalmonae is extensive by examining the proportions of infected statoblasts in populations of F. sultana on two different rivers systems and confirms its effectiveness by demonstrating transmission from material derived from infected statoblast...

Background Studies conducted with gilthead sea bream (Sparus aurata L.) have determined the maximum dietary replacement of fish meal and oil without compromising growth or product quality. The present study aimed to analyze the effect of the nutritional background on fish health and fish fed plant protein-based diets with fish oil (FO diet) or a blend of vegetable oils (66VO diet) were exposed for 102 days to the intestinal myxosporean parasite Enteromyxum leei, and the intestine transcriptome was analyzed with a customized oligo-microarray of 7,500 annotated genes. Results Infection prevalence was high and similar in the two diet groups, but the outcome of the disease was more pronounced in fish fed the 66VO diet. No differences were found in the transcriptome of both diet control groups, whereas the number of differentially expressed genes in infected groups was considerable. K-means clustering of these differentially expressed genes identified four expression patterns that reflec...

A new marine myxosporean species, Ceratomyxa aegyptiaca n. sp. is described from the gall-bladder of Solea aegyptiaca Chabanaud collected from the Ghar El Melh Lagoon in northeastern Tunisia. Mature spores are elongate and crescent-shaped, measuring 8-11 μm in length and 48-58 μm in width. The polar capsules are spherical, 3.2-4 μm in diameter and equal in size. Trophozoites are polysporous and float free in the bile or are attached on the epithelium of the gall-bladder. Morphological data and molecular analysis based on 18S rDNA sequences are provided. The 18S rDNA of C. aegyptiaca is readily distinguishable from that of other myxozoan species, as the genetically most similar myxozoan parasite, C. seriolae Yokoyama & Fukuda, 2001 (AB530265) collected from Seriola quinqueradiata Temminck & Schlegel in Japanese waters, shares with it only 67.5% identical nucleotides over a 1,680-bp long fragment of 18S rDNA.

This study reports on Kudoa spp. (Myxozoa, Multivalvulida) from the fish species Lutjanus analis, Bagre marinus, Aspistor luniscutis and Lutjanus jocu, which were caught in Aracaju, state of Sergipe, Brazil. The parasites formed oval plasmodia around the esophagus of L. analis, and elongated plasmodia inside the skeletal muscle of B. marinus, A. luniscutis and L. jocu. Host myoliquefaction was not observed in all the cases studied. The current study provides a morphological and morphometric description of each parasite as well as a comparison with all the species described worldwide. Lack of molecular data impaired specific identification of the parasites. The importance of these parasites is discussed and the need for further studies on infections in Brazilian fish is emphasized because of the high economic impact of some Kudoa species which cause liquefaction in hosts’ muscles and render these fish unsuitable for consumption.

Malacosporeans represent a small fraction of myxozoan biodiversity with only two genera and three species described. They cycle between bryozoans and freshwater fish. In this study, we (i) microscopically examine and screen different freshwater/marine fish species from various geographic locations and habitats for the presence of malacosporeans using PCR; (ii) study the morphology, prevalence, host species/habitat preference and distribution of malacosporeans; (iii) perform small subunit/large subunit rDNA and Elongation factor 2 based phylogenetic analyses of newly gathered data, together with all available malacosporean data in GenBank; and (iv) investigate the evolutionary trends of malacosporeans by mapping the morphology of bryozoan-related stages, host species, habitat and geographic data on the small subunit rDNA-based phylogenetic tree. We reveal a high prevalence and diversity of malacosporeans in several fish hosts in European freshwater habitats by adding five new species...

Ceratomyxa gouletti n. sp. is a new parasite described from the gallbladder of the red scorpionfish Scorpaena scrofa (Scorpaeniformes: Scorpaenidae) collected from La Goulette in the Northeast of Tunisia. The parasite develops disporic plasmodia, elliptical to ovoid in shape, measuring up to 33.1 ± 3.6 (28.0-38.2) μm in length and 12.5 ± 2.1 (11.3-14.0) μm in width. Mature spores are elongated transversely and crescent-shaped with rounded ends and unequal shell valves, measuring 8.1 ± 1.27 (7.2-9.0) μm in length and 32.0 ± 2.5 (27.0-38.2) μm in thickness. Sutural line is straight and visible between valves. Polar capsules are subspherical with 3.15 ± 0.63 (2.7-3.6) μm long and 1.9 ± 0.14 (1.8-2.0) μm wide. Posterior spore angle is slightly concave 160°-175°. Molecular analysis based on the small subunit 18S rDNA sequence shows that C. gouletti n. sp. is different from all other ceratomyxid species DNA sequences in GenBank. Phylogenetic trees clustered the new species with long-branc...

A new myxosporean, Chloromyxum aegypticus n. sp., is described from the testes of the Egyptian toad Bufo regularis, captured from El Mansoura locality. C. aegypti-cus is identified on the basis of cytology, electron microscopy and histopathology. It is distinguished from ...

A new myxosporean, Chloromyxum aegypticus n. sp., is described from the testes of the Egyptian toad Bufo regularis, captured from El Mansoura locality. C. aegypti-cus is identified on the basis of cytology, electron microscopy and histopathology. It is distinguished from ...

aLaboratory of Ecohydrology, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; bDipartimento di Scienze Ambientali, Informatica e Statistica, Università Ca’ Foscari Venezia, 30170 Venice, Italy; cDipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milan, Italy; dDepartment of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; eInstitute of Integrative Biology, Eidgenössiche Technische Hochschule Zürich, 8092 Zurich, Switzerland; fCentre for Fish and Wildlife Health, University of Bern, 3012 Bern, Switzerland; and gDipartimento di Ingegneria Civile, Edile ed Ambientale, Università di Padova, 35131 Padua, Italy

Enteromyxum scophthalmi, an intestinal myxozoan parasite, is the causative agent of a threatening disease for turbot (Scophthalmus maximus, L.) aquaculture. The colonization of the digestive tract by this parasite leads to a cachectic syndrome associated with high morbidity and mortality rates. This myxosporidiosis has a long pre-patent period and the first detectable clinical and histopathological changes are subtle. The pathogenic mechanisms acting in the early stages of infection are still far from being fully understood. Further information on the host-parasite interaction is needed to assist in finding efficient preventive and therapeutic measures. Here, a RNA-seq-based transcriptome analysis of head kidney, spleen and pyloric caeca from experimentally-infected and control turbot was performed. Only infected fish with early signs of infection, determined by histopathology and immunohistochemical detection of E. scophthalmi, were selected. The RNA-seq analysis revealed, as expec...

During a survey of myxosporean parasites of freshwater fishes in Meerut, Uttar Pradesh (UP), India, spores of Henneguya chaudhuryi (Bajpai & Haldar, 1982) were found in the gill lamellae of the spotted snakehead fish Channa punctata (Bloch) (Perciformes: Channidae). This species was described lacking several characteristics in the original description, which makes challenging the accurate diagnosis. Here, we supplemented its description based on morphological, histological and molecular data. Plasmodia of H. chaudhuryi are oval, measuring 60-100 × 40-68 µm, located intralamellarly. Mature spores are elongate, measuring 10.5-13.2 × 3.6-4.2 µm, with two slightly unequal polar capsules with 6-7 filamental turns and two straight, equal caudal appendages, 10-17 µm long. Scanning electron microscopy revealed a flat surface. The 18S rDNA sequence for H. chaudhuryi did not show a close relationship with those of any other Henneguya spp., represented in the GenBank.

SUMMARYProliferative kidney disease (PKD) of salmonids, caused by Tetracapsuloides bryosalmonae, can lead to high mortalities at elevated water temperature. We evaluated the hypothesis that this mortality is caused by increasing parasite intensity. T. bryosalmonae-infected rainbow trout (Oncorhynchus mykiss) were reared at different water temperatures and changes in parasite concentrations in the kidney were compared to cumulative mortalities. Results of parasite quantification by a newly developed real-time PCR agreed with the number of parasites detected by immunohistochemistry, except for very low or very high parasite loads because of heterogenous distribution of the parasites in the kidney. Two experiments were performed, where fish were exposed to temperatures of 12, 14, 16, 18 or 19°C after an initial exposure to an infectious environment at 12–16°C resulting in 100% prevalence of infected fish after 5 to 14 days of exposure. While mortalities differed significantly between a...

Ten new types of sphaeractinomyxon actinospores are morphologically and molecularly described from the coelomic cavity of two marine oligochaete hosts, Limnodriloides agnes (Hrabě, 1967) and Tubificoides pseudogaster (Dahl, 1960), from Aveiro estuary, Portugal. The smallest sphaeractinomyxon type measured 17 μm (length) × 19 μm (width) × 19 μm (apical diameter), whereas the largest type measured 61 μm × 76 μm × 80 μm. While considering the 10 types of sphaeractinomyxon, it was found that the number of spores developing inside pansporocysts varied between 1, 2, 4, and 8. The total prevalence of infection was of 19 % for the two host species, with a maximum recorded for spring and summer (25-26 %). While considering each type of sphaeractinomyxon individually, it was found that the prevalence values ranged between 0.3 and 1.7 %. All described sphaeractinomyxons were most similar to Myxobolus species. The validity of the tetraspora and endocapsa collective group names is discussed.

The aim of the present work was to investigate the transcriptome response of gilthead sea bream (Sparus aurata) after challenge with the myxosporean Enteromyxum leei, a wide-spread enteric parasite causing heavy economic losses in Mediterranean sparid farms. This parasite causes severe desquamative enteritis which usually leads to death of the fish, and there are no preventative or curative treatments for this enteromyxosis. After 113 days of exposure to parasite-contaminated effluent, fish were classified into three cohorts: control fish not exposed to parasite, those that were exposed and infected, and those that were exposed but not infected. In order to detect target genes that may be candidates for infective status or resistance, a cDNA microarray containing 18,490 cDNA clones enriched in genes differentially expressed after infection was hybridised with head kidney and intestine samples. In infected fish, 371 and 373 genes were differentially regulated at the >1.5-fold level in intestine and head kidney respectively, whereas in non-infected fish 175 and 501 genes were differentially regulated in these tissues, respectively. A global marked gene down-regulation was evident in infected fish, mainly in genes involved in the immune and acute phase response particularly complement and mannose binding lectin. Microarray analysis demonstrated a complex interplay between host and/or parasite derived proteases and protease inhibitors, apoptosis, cell proliferation and antioxidant defence genes in exposed fish. In the head kidney of non-infected fish a marked depression of genes involved in the acute phase response was evident. By contrast, in the intestine of non-infected fish, interferon-stimulated and MHC class II genes involved in antigen processing and presentation were up-regulated, possibly indicating that an active immune response at the local level is important to avoid infection with or proliferation of the parasite.