Search

The haptophyte alga Prymnesium parvum (Prymnesiophyceae) caused “creeping” mortality in ornamental fish, molly (Poecilia sp.) and koi (Japanese carp, Cyprinus carpio), farmed in the Arava Valley in southern Israel. The toxicosis occurred when the water system was changed from flow-through to closed circulation. A moderately high temperature, three-fold increase of salinity, and probable rise in eutrophication created conditions suitable to P. parvum blooms. The system was treated with 10 ppm ammonium sulfate and fish mortality ceased.

The haptophyte alga Prymnesium parvum (Prymnesiophyceae) caused “creeping” mortality in ornamental fish, molly (Poecilia sp.) and koi (Japanese carp, Cyprinus carpio), farmed in the Arava Valley in southern Israel. The toxicosis occurred when the water system was changed from flow-through to closed circulation. A moderately high temperature, three-fold increase of salinity, and probable rise in eutrophication created conditions suitable to P. parvum blooms. The system was treated with 10 ppm ammonium sulfate and fish mortality ceased.

The haptophyte alga Prymnesium parvum (Prymnesiophyceae) caused “creeping” mortality in ornamental fish, molly (Poecilia sp.) and koi (Japanese carp, Cyprinus carpio), farmed in the Arava Valley in southern Israel. The toxicosis occurred when the water system was changed from flow-through to closed circulation. A moderately high temperature, three-fold increase of salinity, and probable rise in eutrophication created conditions suitable to P. parvum blooms. The system was treated with 10 ppm ammonium sulfate and fish mortality ceased.

Traditionally, the most common approach to diagnosis of microbial fish pathogens has relied on in vitro isolation of the microorganism and the information provided by its phenotypic features. However, viruses are generally highly species-specific and established cell lines do not neces- sarily show cytopathic effect, many species of bacteria are difficult or impossible to culture in vitro, while parasitic microorganisms often have a complex life cycle that requires propagation in live hosts. An increasing number of microbial pathogens are identified today by molecular meth- ods, without the need for isolation. A PCR direct method for detection and identification of Mycobacterium marinum based on the 16S rRNA gene sequence was successfully developed already 13 years ago at NCM. Comparison of the 16S rRNA sequence of Streptococcus iniae isolates revealed that, despite phenotypic, biochemical and pathogenetic similarities, marine and freshwater isolates were different strains. With time, however, it has become clear that 16S rRNA gene sequences alone are often insufficient to detect variation within bacterial species, and today other specific loci are also being employed. More recently, on the basis of hsp65 gene in addition to 16S rRNA gene, Israeli M. marinum isolates in marine and freshwater fish were found to belong to two distinct strains, and both were different from Israeli M. marinum clinical (human) isolates. Specific 18S rDNA probes for detection of elusive life stages of two myx- osporean parasites, Kudoa iwatai and Enteromyxum leei, in sea bream and sea bass are being employed in studies conducted over the last few years at NCM. By using whole-genome struc- tures rather than single gene sequences, two fingerprinting techniques - Amplified Fragment Length Polymorphism (AFLP) and Randomly Amplified Polymorphic DNA (RAPD) - have pro- vided a generally higher level of precision in genotyping. However, while the AFLP method revealed broad polymorphism among S. i

Traditionally, the most common approach to diagnosis of microbial fish pathogens has relied on in vitro isolation of the microorganism and the information provided by its phenotypic features. However, viruses are generally highly species-specific and established cell lines do not neces- sarily show cytopathic effect, many species of bacteria are difficult or impossible to culture in vitro, while parasitic microorganisms often have a complex life cycle that requires propagation in live hosts. An increasing number of microbial pathogens are identified today by molecular meth- ods, without the need for isolation. A PCR direct method for detection and identification of Mycobacterium marinum based on the 16S rRNA gene sequence was successfully developed already 13 years ago at NCM. Comparison of the 16S rRNA sequence of Streptococcus iniae isolates revealed that, despite phenotypic, biochemical and pathogenetic similarities, marine and freshwater isolates were different strains. With time, however, it has become clear that 16S rRNA gene sequences alone are often insufficient to detect variation within bacterial species, and today other specific loci are also being employed. More recently, on the basis of hsp65 gene in addition to 16S rRNA gene, Israeli M. marinum isolates in marine and freshwater fish were found to belong to two distinct strains, and both were different from Israeli M. marinum clinical (human) isolates. Specific 18S rDNA probes for detection of elusive life stages of two myx- osporean parasites, Kudoa iwatai and Enteromyxum leei, in sea bream and sea bass are being employed in studies conducted over the last few years at NCM. By using whole-genome struc- tures rather than single gene sequences, two fingerprinting techniques - Amplified Fragment Length Polymorphism (AFLP) and Randomly Amplified Polymorphic DNA (RAPD) - have pro- vided a generally higher level of precision in genotyping. However, while the AFLP method revealed broad polymorphism among S. i

Traditionally, the most common approach to diagnosis of microbial fish pathogens has relied on in vitro isolation of the microorganism and the information provided by its phenotypic features. However, viruses are generally highly species-specific and established cell lines do not neces- sarily show cytopathic effect, many species of bacteria are difficult or impossible to culture in vitro, while parasitic microorganisms often have a complex life cycle that requires propagation in live hosts. An increasing number of microbial pathogens are identified today by molecular meth- ods, without the need for isolation. A PCR direct method for detection and identification of Mycobacterium marinum based on the 16S rRNA gene sequence was successfully developed already 13 years ago at NCM. Comparison of the 16S rRNA sequence of Streptococcus iniae isolates revealed that, despite phenotypic, biochemical and pathogenetic similarities, marine and freshwater isolates were different strains. With time, however, it has become clear that 16S rRNA gene sequences alone are often insufficient to detect variation within bacterial species, and today other specific loci are also being employed. More recently, on the basis of hsp65 gene in addition to 16S rRNA gene, Israeli M. marinum isolates in marine and freshwater fish were found to belong to two distinct strains, and both were different from Israeli M. marinum clinical (human) isolates. Specific 18S rDNA probes for detection of elusive life stages of two myx- osporean parasites, Kudoa iwatai and Enteromyxum leei, in sea bream and sea bass are being employed in studies conducted over the last few years at NCM. By using whole-genome struc- tures rather than single gene sequences, two fingerprinting techniques - Amplified Fragment Length Polymorphism (AFLP) and Randomly Amplified Polymorphic DNA (RAPD) - have pro- vided a generally higher level of precision in genotyping. However, while the AFLP method revealed broad polymorphism among S. i

A case of mycobacteriosis in European sea bass (Dicentrarchus labrax L.) cultured in Turkey is described. Diseased fish were characterized by lethargy, lingering passively at the water sur- face, pale gills, and exophthalmia. Internally, grayish-white nodules were observed in the liver, spleen, and kidney. In one individual, a granulomatous mass of renal origin protruded into the abdominal cavity. The principal histological feature was the occurrence of characteristic granu- lomas with associated acid-fast, rod-shaped bacteria. This is the first confirmed case of fish mycobacteriosis in Turkey.

A case of mycobacteriosis in European sea bass (Dicentrarchus labrax L.) cultured in Turkey is described. Diseased fish were characterized by lethargy, lingering passively at the water sur- face, pale gills, and exophthalmia. Internally, grayish-white nodules were observed in the liver, spleen, and kidney. In one individual, a granulomatous mass of renal origin protruded into the abdominal cavity. The principal histological feature was the occurrence of characteristic granu- lomas with associated acid-fast, rod-shaped bacteria. This is the first confirmed case of fish mycobacteriosis in Turkey.

A case of mycobacteriosis in European sea bass (Dicentrarchus labrax L.) cultured in Turkey is described. Diseased fish were characterized by lethargy, lingering passively at the water sur- face, pale gills, and exophthalmia. Internally, grayish-white nodules were observed in the liver, spleen, and kidney. In one individual, a granulomatous mass of renal origin protruded into the abdominal cavity. The principal histological feature was the occurrence of characteristic granu- lomas with associated acid-fast, rod-shaped bacteria. This is the first confirmed case of fish mycobacteriosis in Turkey.