Project description:Myxosporean parasites of the genus Kudoa are fish parasites of great economic importance, as some species can affect the fish fillet quality by producing macroscopic cysts or generating post mortem myoliquefaction, commonly referred to as 'soft flesh'. Kudoa mirabilis is a 'soft flesh'-inducing species originally described based on morphology in the musculature of Trichiurus lepturus from the Indian Ocean. An integrative morphological and genetic characterization of K. mirabilis from the type host caught off the coast of Tanzania is here provided. The spores were stellate with four unequal polar capsules, showing similarities to Kudoa thyrsites. For comparative and validation purpose, K. mirabilis was compared morphologically and genetically with K. thyrsites reference isolates, including new obtained samples from the type host Thyrsites atun caught in the SE Atlantic Ocean. Morphological analyses of spores revealed key diagnostic characters clearly distinguishing the two Kudoa species. Phylogenetic analyses based on SSU and LSU rRNA genes demonstrated that K. mirabilis is a distinct and valid species, representing a sister group to a K. thyrsites subclade that comprises several isolates from Japan and one single isolate from South Africa. This finding raises questions about the true diversity likely hidden in the K. thyrsites complex.

| S-EPMC7565053 | biostudies-literature

Kudoa ogawai (Myxosporea: Kudoidae) Infection in Cultured Olive Flounder Paralichthys olivaceus.

Project description:Since Kudoa septempuntata was identified as a causative agent of food poisoning associated with raw olive flounder Paralichthys olivaceus, interest and concern regarding the parasite have increased. However, there have been no investigations or reports of other Kudoa species infecting the fish (except for K. paralichthys, which infects the brain) in Korea. We found cysts filled with myxospores of Kudoa species in muscles of cultured olive flounder specimens and identified these to the species level. Mature spores were quadrate, measuring 8.7±0.5 μm in length, 9.2±0.4 μm in thickness, and 12.9±0.6 μm in width. The spores containing 4 polar capsules had a length of 2.1±0.2 μm and a width of 1.8±0.3 μm. The partial 18S and 28S rDNA of isolates showed 99-100% similarities with K. ogawai. Using these morphological and molecular analyses, the species was identified as K. ogawai. This study is the first report of K. ogawai infection in cultured olive flounder in Korea.

| S-EPMC6753299 | biostudies-literature

The Mitochondrial Genomes of a Myxozoan Genus Kudoa Are Extremely Divergent in Metazoa.

Project description:The Myxozoa are oligo-cellular parasites with alternate hosts--fish and annelid worms--and some myxozoan species harm farmed fish. The phylum Myxozoa, comprising 2,100 species, was difficult to position in the tree of life, due to its fast evolutionary rate. Recent phylogenomic studies utilizing an extensive number of nuclear-encoded genes have confirmed that Myxozoans belong to Cnidaria. Nevertheless, the evolution of parasitism and extreme body simplification in Myxozoa is not well understood, and no myxozoan mitochondrial DNA sequence has been reported to date. To further elucidate the evolution of Myxozoa, we sequenced the mitochondrial genomes of the myxozoan species Kudoa septempunctata, K. hexapunctata and K. iwatai and compared them with those of other metazoans. The Kudoa mitochondrial genomes code for ribosomal RNAs, transfer RNAs, eight proteins for oxidative phosphorylation and three proteins of unknown function, and they are among the metazoan mitochondrial genomes coding the fewest proteins. The mitochondrial-encoded proteins were extremely divergent, exhibiting the fastest evolutionary rate in Metazoa. Nevertheless, the dN/dS ratios of the protein genes in genus Kudoa were approximately 0.1 and similar to other cnidarians, indicating that the genes are under negative selection. Despite the divergent genetic content, active oxidative phosphorylation was indicated by the transcriptome, metabolism and structure of mitochondria in K. septempunctata. As possible causes, we attributed the divergence to the population genetic characteristics shared between the two most divergent clades, Ctenophora and Myxozoa, and to the parasitic lifestyle of Myxozoa. The fast-evolving, functional mitochondria of the genus Kudoa expanded our understanding of metazoan mitochondrial evolution.

| S-EPMC4492933 | biostudies-literature

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