To identify the pathogens causing saprolegniosis among farmed fish in Nova Scotia, 172 infected tissues and 23 water samples were collected from six species of teleosts: Atlantic salmon (Salmo salar), brown trout (Salmo trutta), Arctic charr (Salvelinus alpinus), brook trout (Salvelinus fontinalis), striped bass (Morone saxatilis) and rainbow trout (Oncorhynchus mykiss) at nine facilities over a 600 km range. Following laboratory culture, 132 isolates were recovered. Six species of oomycetes were identified from analysis of the internal transcribed spacer (ITS) sequence of the nrDNA: Saprolegnia parasitica, Saprolegnia ferax, Saprolegnia diclina, Saprolegnia aenigmatica, Saprolegnia torulosa, Saprolegnia sp. and Pythiopsis cymosa. Further phylogenetic analyses of the ITS and cytochrome c oxidase subunit 1 (Cox1) regions revealed four strains of Saprolegnia parasitica (named here as S1, S2, S3 and S4), of which S1 and S2 were common (37% and 42% of the isolates), and two strains of S. ferax. Among S. parasitica, S2 and S3 are more closely related to each other than to S1 based on the phylogenetic analyses and predicted RNA secondary structure of the ITS region. Sexual structures with a similar morphology were formed by S1 and S3 in vitro, but were not formed by S2.
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http://dx.doi.org/10.1111/jfd.13090 | DOI Listing |
Dev Comp Immunol
January 2025
National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China; National Pathogen Collection Center for Aquatic Animals, Shanghai Ocean University, Shanghai, China; Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai, China. Electronic address:
Saprolegniasis is a common fungal disease in aquaculture. It will form white flocculent hyphae on the skin of fish, and the hyphae may grow inward and penetrate into muscle tissue, which will reduce the immunity of the body and eventually lead to death. However, there are still some gaps in the mechanism of the fish body surface against the invasion of Saprolegnia.
View Article and Find Full Text PDFSaprolegniasis is one of the most dangerous fungal diseases of fish, causing significant mortality in fish hatcheries and young ones. The present study aimed to isolate and characterize the causative fungus from fingerlings of Pangasianodon hypophthalmus cultured intensively in freshwater cages in Indian reservoirs and to determine minimum inhibitory concentrations of different antifungal compounds against the fungal hyphae and zoospores. The fungal isolates grown on potato dextrose agar showed an abundance of gemmae, elongated mycelia, non-septate hyphae, primary zoospores, mature zoosporangia with numerous zoospores, cysts with bundles of long hairs and were further identified as Saprolegnia parasitica following PCR amplification and sequencing of internal transcribed spacer region.
View Article and Find Full Text PDFJ Fish Dis
December 2024
Laboratory of Population Biology, Department of Marine Biosciences, Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Minato, Tokyo, Japan.
The pejerrey (Odontesthes bonariensis) is a key species for recreational and commercial fisheries in Argentina and holds significant aquaculture potential. It has been introduced to various countries worldwide, including Japan, where intensive aquaculture has developed. However, infectious diseases present major challenges to its cultivation, as pejerrey is susceptible to diverse pathogens, including bacteria, fungi and parasites.
View Article and Find Full Text PDFMar Biotechnol (NY)
November 2024
State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Provincial Key Laboratory for Microbial Molecular Biology, College of Life Science, Hunan Normal University, Changsha, China.
Saprolegniasis caused by Saprolegnia parasitica leads to significant economic losses in the aquaculture industry worldwide. Effector proteins secreted by pathogens are key molecules involved in their pathogenicity and long non-coding lncRNAs (lncRNAs) act as regulators in these processes. However, little is known about the lncRNAs and effector proteins in S.
View Article and Find Full Text PDFFish Shellfish Immunol
November 2024
National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China; National Pathogen Collection Center for Aquatic Animals, Shanghai Ocean University, Shanghai, China; Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai, China. Electronic address:
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