The Vibrionaceae are a family of Proteobacteria containing some of the most important fish pathog... more The Vibrionaceae are a family of Proteobacteria containing some of the most important fish pathogens including Vibrio and Photobacterium species. Members of these two genera have been devastating the Mediterranean aquaculture for many years. In this work we present data on the biochemical and molecular characterization of several clinical strains isolated from Greek aquacultures. Most of these clinical strains belong to the following species: Vibrio anguillarum, V. harveyi, V. parahaemolyticus, V. fischeri, Photobacterium damselae subsp. piscicida, Photobacterium damselae subsp. damselae. The biochemical characterization was based on the BIOLOG GEN III standardized micromethod which is using 71 carbon source utilization assays and 23 chemical sensitivity assays to provide a phenotypic fingerprint of the bacteria. The strains were grouped using Direct Genome Restriction Enzyme Analysis (DGREA) and the 16S ribosomal RNA of the representatives of each group were sequenced following PCR...
ABSTRACT Edwardsiella tarda, a serious bacterial pathogen, affects a wide range of fish species m... more ABSTRACT Edwardsiella tarda, a serious bacterial pathogen, affects a wide range of fish species mostly in warm waters. The bacterium is responsible for important economic losses in the aquaculture industry of the USA and Asia while there are few reports from Europe and the Mediterranean. Here we report (i) the isolation of E. tarda from two sparids, the common pandora, Pagellus erythrinus & the sharpsnout sea bream, Diplodus puntazzo, reared in Greece, (ii) the characterization of the pathogen and (iii) preliminary results on the isolation of lytic bacteriophages against this bacterium aiming to the future development of biological treatment method for the disease. Bacteriology The bacteria were initially isolated in blood agar where they formed small distinct colonies. Bacterial isolates were identified to species level using biochemical (API 20E and BIOLOG GENIII) and molecular tools (16s and gyrB sequencing). They were Gram negative, motile rods identified as E. tarda with 55% probability using BIOLOG GENIII system The bacteriun can utilize several carbon sources such as sugars (maltose, glucose, N-Acetyl-D-glycosamine, N-Acetyl-neuraminic acid, mannose, fructose, glucose-6-PO4, fructose-6-PO4, serine), aminoacids (galacturonic acid, gluconic acid, glucuronic acid) and caroboxylic acid (lactic acid), it cannot grow in salinity exceeding 4% NaCl and it is resistant in acidic pH while H 2 S production varies. It grew in 20, 25 and 30 o C with optimum being the latest. Discussion and conclusion This the first report of E. tarda in aquaculture fish in Greece and one of the few in the Mediterranean (Alcaide et al., 2006). The current isolate contains all virulent genes described in literature and showed increased virulence against fish larvae indicating that it could potentially pose an emerging threat to the aquaculture industry. The disease is usually treated with antibiotics while vaccination is still being investigated (Park et al., 2012) thus making the pursuit of alternatives a priority. Towards this direction, phage therapy could provide an attractive solution since phages are natural predators of bacteria, they are highly host specific and can eliminate the bacterial host without affecting the environmental microflora and fish gut microbiota. The phages isolated here have suitable characteristics and could be promising candidates for developing phage therapy schemes.
ABSTRACT Nine biotic indices and benthic macroinvertebrates scores used for the assessment of wat... more ABSTRACT Nine biotic indices and benthic macroinvertebrates scores used for the assessment of water quality over a period of one year at the rivers Kalamas and Alfeios (Greece) were compared. The results of the biotic indexes were combined with the measurements of physicochemical parameters, in order to assess the water quality and to find the most applicable index for assessing Greek rivers. The indexes BBI and IBE were found to be more suitable. However, the need for the establishment of a Greek Biotic Index for assessment of the rivers in the Greek region is marked out.
Two members of Aulopiformes (grinners) were examined for myxosporean parasites in their gallbladd... more Two members of Aulopiformes (grinners) were examined for myxosporean parasites in their gallbladders. Synodus saurus and Aulopus filamentosus from Cretan Sea, Greece were infected by Ceratomyxa parasites which are described in this paper. Both species of Ceratomyxa are new and referred for the first time as Ceratomyxa cretensis n.sp. and Ceratomyxa filamentosi n.sp. The new species are described morphologically by light and scanning electron microscopy analysis, and characterized genetically by sequencing the small subunit (SSU) rDNA. The SSU rDNA sequences obtained from the two novel Ceratomyxa species were used for the construction of a phylogenetic tree with all the available Ceratomyxa SSU rDNA sequences.
Ultrastructure of mature spermatozoon of Anisocoelium capitellatum is described with transmission... more Ultrastructure of mature spermatozoon of Anisocoelium capitellatum is described with transmission electron microscopy. The description gave evidence of some characteristics of this digenean. The male gamete presents features allowing the distinction between A. capitellatum and other digenetic trematodes. It is characterized by original anterior and posterior extremities. The peripheral doublets appear prior to the central cores in the anterior extremity of axoneme. In the distal part of the spermatozoon, these ultrastructural features are also the first elements disappearing in the axoneme 1 and the last remaining in the axoneme 2. Another important peculiarity of the spermatozoon is the presence of three mitochondria.
The lethal effect of enteromyxosis is recorded for the first time in the humphead wrasse, Cheilin... more The lethal effect of enteromyxosis is recorded for the first time in the humphead wrasse, Cheilinus undulatus, a tropical pet fish. Enteromyxosis was caused by the myxosporean parasite Enteromyxum leei, and the gut was the only tissue affected in this case. Severe enteritis and degeneration of the intestinal mucosa may have caused a digestive function disorder, thereby resulting in the fish's death. The histopathological findings of this case included destruction of normal tissue architecture of the intestinal mucosa, chronic inflammation, and infiltration of mast cells/eosinophilic granular cells, which resembled findings described in other fish that were diagnosed with enteromyxosis. Induced stress by transportation and entrance to a new environment possibly played an underlying role in the virulence of the parasitic infection and associated tissue pathology.
The Vibrionaceae are a family of Proteobacteria containing some of the most important fish pathog... more The Vibrionaceae are a family of Proteobacteria containing some of the most important fish pathogens including Vibrio and Photobacterium species. Members of these two genera have been devastating the Mediterranean aquaculture for many years. In this work we present data on the biochemical and molecular characterization of several clinical strains isolated from Greek aquacultures. Most of these clinical strains belong to the following species: Vibrio anguillarum, V. harveyi, V. parahaemolyticus, V. fischeri, Photobacterium damselae subsp. piscicida, Photobacterium damselae subsp. damselae. The biochemical characterization was based on the BIOLOG GEN III standardized micromethod which is using 71 carbon source utilization assays and 23 chemical sensitivity assays to provide a phenotypic fingerprint of the bacteria. The strains were grouped using Direct Genome Restriction Enzyme Analysis (DGREA) and the 16S ribosomal RNA of the representatives of each group were sequenced following PCR...
ABSTRACT Edwardsiella tarda, a serious bacterial pathogen, affects a wide range of fish species m... more ABSTRACT Edwardsiella tarda, a serious bacterial pathogen, affects a wide range of fish species mostly in warm waters. The bacterium is responsible for important economic losses in the aquaculture industry of the USA and Asia while there are few reports from Europe and the Mediterranean. Here we report (i) the isolation of E. tarda from two sparids, the common pandora, Pagellus erythrinus & the sharpsnout sea bream, Diplodus puntazzo, reared in Greece, (ii) the characterization of the pathogen and (iii) preliminary results on the isolation of lytic bacteriophages against this bacterium aiming to the future development of biological treatment method for the disease. Bacteriology The bacteria were initially isolated in blood agar where they formed small distinct colonies. Bacterial isolates were identified to species level using biochemical (API 20E and BIOLOG GENIII) and molecular tools (16s and gyrB sequencing). They were Gram negative, motile rods identified as E. tarda with 55% probability using BIOLOG GENIII system The bacteriun can utilize several carbon sources such as sugars (maltose, glucose, N-Acetyl-D-glycosamine, N-Acetyl-neuraminic acid, mannose, fructose, glucose-6-PO4, fructose-6-PO4, serine), aminoacids (galacturonic acid, gluconic acid, glucuronic acid) and caroboxylic acid (lactic acid), it cannot grow in salinity exceeding 4% NaCl and it is resistant in acidic pH while H 2 S production varies. It grew in 20, 25 and 30 o C with optimum being the latest. Discussion and conclusion This the first report of E. tarda in aquaculture fish in Greece and one of the few in the Mediterranean (Alcaide et al., 2006). The current isolate contains all virulent genes described in literature and showed increased virulence against fish larvae indicating that it could potentially pose an emerging threat to the aquaculture industry. The disease is usually treated with antibiotics while vaccination is still being investigated (Park et al., 2012) thus making the pursuit of alternatives a priority. Towards this direction, phage therapy could provide an attractive solution since phages are natural predators of bacteria, they are highly host specific and can eliminate the bacterial host without affecting the environmental microflora and fish gut microbiota. The phages isolated here have suitable characteristics and could be promising candidates for developing phage therapy schemes.
ABSTRACT Nine biotic indices and benthic macroinvertebrates scores used for the assessment of wat... more ABSTRACT Nine biotic indices and benthic macroinvertebrates scores used for the assessment of water quality over a period of one year at the rivers Kalamas and Alfeios (Greece) were compared. The results of the biotic indexes were combined with the measurements of physicochemical parameters, in order to assess the water quality and to find the most applicable index for assessing Greek rivers. The indexes BBI and IBE were found to be more suitable. However, the need for the establishment of a Greek Biotic Index for assessment of the rivers in the Greek region is marked out.
Two members of Aulopiformes (grinners) were examined for myxosporean parasites in their gallbladd... more Two members of Aulopiformes (grinners) were examined for myxosporean parasites in their gallbladders. Synodus saurus and Aulopus filamentosus from Cretan Sea, Greece were infected by Ceratomyxa parasites which are described in this paper. Both species of Ceratomyxa are new and referred for the first time as Ceratomyxa cretensis n.sp. and Ceratomyxa filamentosi n.sp. The new species are described morphologically by light and scanning electron microscopy analysis, and characterized genetically by sequencing the small subunit (SSU) rDNA. The SSU rDNA sequences obtained from the two novel Ceratomyxa species were used for the construction of a phylogenetic tree with all the available Ceratomyxa SSU rDNA sequences.
Ultrastructure of mature spermatozoon of Anisocoelium capitellatum is described with transmission... more Ultrastructure of mature spermatozoon of Anisocoelium capitellatum is described with transmission electron microscopy. The description gave evidence of some characteristics of this digenean. The male gamete presents features allowing the distinction between A. capitellatum and other digenetic trematodes. It is characterized by original anterior and posterior extremities. The peripheral doublets appear prior to the central cores in the anterior extremity of axoneme. In the distal part of the spermatozoon, these ultrastructural features are also the first elements disappearing in the axoneme 1 and the last remaining in the axoneme 2. Another important peculiarity of the spermatozoon is the presence of three mitochondria.
The lethal effect of enteromyxosis is recorded for the first time in the humphead wrasse, Cheilin... more The lethal effect of enteromyxosis is recorded for the first time in the humphead wrasse, Cheilinus undulatus, a tropical pet fish. Enteromyxosis was caused by the myxosporean parasite Enteromyxum leei, and the gut was the only tissue affected in this case. Severe enteritis and degeneration of the intestinal mucosa may have caused a digestive function disorder, thereby resulting in the fish's death. The histopathological findings of this case included destruction of normal tissue architecture of the intestinal mucosa, chronic inflammation, and infiltration of mast cells/eosinophilic granular cells, which resembled findings described in other fish that were diagnosed with enteromyxosis. Induced stress by transportation and entrance to a new environment possibly played an underlying role in the virulence of the parasitic infection and associated tissue pathology.
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