Molecular characterization of the fish-pathogenic fungus Aphanomyces invadans.

• Aphanomyces invadans (Saprolegniaceae) is a peronosporomycete fungus associated with the serious fish disease, epizootic ulcerative syndrome (EUS), also known as mycotic granulomatosis. In this study, interspecific relationships were examined between A. invadans isolates and other aquatic animal pathogenic Saprolegniaceae, and saprophytic Saprolegniaceae from EUS-affected areas. Restriction fragment length polymorphisms and sequences of ribosomal DNA confirmed that A. invadans is distinct from all other species studied. A sequence from the internal transcribed spacer region ITS1, unique to A. invadans, was used to design primers for a PCR-based diagnostic test. Intraspecific relationships were also examined by random amplification of polymorphic DNA using 20 isolates of A. invadans from six countries. The isolates showed a high degree of genetic homogeneity using 14 random ten-mer primers. This provides evidence that the fungus has spread across Asia in one relatively rapid episode, which is consistent with reports of outbreaks of EUS. Physiological distinctions between A. invadans and other Aphanomyces species based on a data set of 16 growth parameters showed remarkable taxonomic congruence with the molecular phylogeny.

Subject headings

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Keyword

Animals

Aphanomyces

classification

genetics

growth

development

Base Sequence

Cluster Analysis

Consensus Sequence

DNA Primers

chemistry

DNA

Ribosomal

Fish Diseases

diagnosis

microbiology

Fishes

Granuloma

veterinary

Molecular Sequence Data

Mycoses

Polymerase Chain Reaction

Polymorphism

Restriction Fragment Length

Random Amplified Polymorphic DNA Technique

Biology

Biologi

Publication and Content Type

ref (subject category)

art (subject category)