Advances in the knowledge of amphizoic amoebae infecting fish

Dyková, Iva; Lom, J.

doi:10.14411/fp.2004.014

Cited by 46 publications

(45 citation statements)

References 84 publications

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“…However, recent research on AGD has suggested that some cultured strains of Neoparamoeba sp. isolated from AGD infected fish gills are not bacterivorous (Dyková & Lom 2004). Despite this, during the present study the fish inoculated with Winogradskyella sp.…”

Section: Discussionmentioning

confidence: 67%

Influence of salmonid gill bacteria on development and severity of amoebic gill disease

Embar-Gopinath¹,

Bütler²,

Nowak³

2005

Dis. Aquat. Org.

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ABSTRACT:The relationship between salmonid gill bacteria and Neoparamoeba sp., the aetiological agent of amoebic gill disease (AGD) was determined in vivo. Fish were divided into 4 groups and were subjected to following experimental infections: Group 1, amoebae only; Group 2, Staphylococcus sp. and amoebae; Group 3, Winogradskyella sp. and amoebae; Group 4, no treatment (control). Fish (Groups 1, 2 and 3) were exposed to potassium permanganate to remove the natural gill microflora prior to either bacterial or amoebae exposure. AGD severity was quantified by histological analysis of gill sections to determine the percentage of lesioned filaments and the number of affected lamellae within each lesion. All amoebae infected groups developed AGD, with fish in Group 3 showing significantly more filaments with lesions than other groups. Typically lesion size averaged between 2 to 4 interlamellar units in all AGD infected groups. The results suggest that the ability of Neoparamoeba sp. to infect filaments and cause lesions might be enhanced in the presence of Winogradskyella sp. The possibility is proposed that the prevalence of more severe AGD is due to the occurrence of Winogradskyella sp. at high concentrations on the gills.KEY WORDS: Neoparamoeba · Winogradskyella · AGD · Potassium permanganate · Protozoan diseases · Salmon diseases · Amoeba · Bacteria Resale or republication not permitted without written consent of the publisherDis Aquat Org 67: [55][56][57][58][59][60] 2005 MATERIALS AND METHODS Fish. Atlantic salmon Salmo salar L. (n = 72; mean weight = 88 g) were acclimatised to sea water (35 ‰, 1 µm filtered) over a week in 6 identical recirculating systems each consisting of three 70 l tanks (n = 4 fish per tank) and a 70 l reservoir. A sentinel population (n = 12) of the same body weight was acclimatised in a static tank (210 l). Following acclimatisation, fish in the recirculating systems were divided into 3 treatment groups (n = 12 fish per treatment). Each treatment was duplicated. The 4th group was the sentinel population (n = 12). Fish in Group 1 were exposed to amoebae only (positive control); Group 2, Gram positive bacteria (Staphylococcus sp.) and amoebae; Group 3, Gram negative bacteria (Winogradskyella sp.) and amoebae; Group 4 did not receive any treatment. Sea water temperature was maintained at 16 ± 0.5°C, pH 8.2, dissolved oxygen 7.6 mg l -1 , salinity 35 ‰ and total ammonia-nitrogen below 0.2 mg l -1 . Sufficient air supply was maintained in the tanks throughout the experiment by using aerators.Neoparamoeba sp. isolation. Neoparamoeba sp. were harvested from the AGD affected Atlantic salmon held in the Aquaculture Centre, University of Tasmania, Launceston by a method described by Morrison et al. (2004). In brief, infected gills were removed from AGD affected Atlantic salmon after euthanasia (anaesthetic overdose at 20 ml l -1 Aqui-S ® ). Gills were transported to the laboratory in sterile sea water (SS) containing antibiotic and antimycotic solution (5% v/v 5000 IU ml -1 penicillin and 5 mg...

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Section: Discussionmentioning

confidence: 67%

Influence of salmonid gill bacteria on development and severity of amoebic gill disease

Embar-Gopinath¹,

Bütler²,

Nowak³

2005

Dis. Aquat. Org.

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“…Six of them were subjected to sequence and riboprinting analyses of SSU rRNA genes (Dyková et al 2001, Dyková andLom, 2004). Phylogenetic analyses resulted in identification of one strain from the brain of a fish with Naegleria australiensis and another five strains as closely related to N. clarki.…”

Section: Fish-isolated Naegleria Strains and Their Phylogeny Inferredmentioning

confidence: 99%

Fish-isolated Naegleria strains and their phylogeny inferred from ITS and SSU rDNA sequences

Dyková¹,

Pecková²,

Fiala³

et al. 2006

FOLIA PARASIT

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Abstract. Effort was made to identify Naegleria strains isolated from organs of fish, using phylogenetic analyses of SSU rDNA and ITS sequences. Eighteen fish-isolated strains studied enlarged substantially the so far available set of Naegleria strains characterized by both molecular markers. The phylogenetic analyses of separate and concatenated SSU rDNA and ITS sequences revealed phylogenetic relationships of strains under study; however, they failed to solve classification of fish-isolated strains into species. The sequence similarity of strain-representatives of Naegleria species as well as data obtained on intragenomic variation of ITS sequences discouraged the authors from the definition of new species. The results of the present study provide evidence of a need to re-evaluate the current practice of setting boundaries between species of the genus Naegleria. Sequences obtained in this study have been deposited in GenBank with accession numbers DQ768714-DQ768743.

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“…Subsequently, other amoebae species have been implicated in gill disease including Thecamoeba hoffmani in rainbow trout Oncorhynchus mykiss, Neoparamoeba pemaquidensis in Atlantic salmon Salmo salar, Platyamoeba sp. in turbot Scophthalmus maximus, and other unidentified amoebae in Atlantic salmon and rainbow trout (Leiro et al 1998, Bermingham & Mulcahy 2004, Dyková & Lom 2004, Buchmann et al 2004.…”

Section: Introductionmentioning

confidence: 99%

Neoparamoeba sp. and other protozoans on the gills of Atlantic salmon Salmo salar smolts in seawater

Bermingham¹,

Mulcahy²

2007

Dis. Aquat. Org.

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Protozoan isolates from the gills of marine-reared Atlantic salmon Salmo salar smolts were cultured, cloned and 8 dominant isolates were studied in detail. The light and electron-microscopical characters of these isolates were examined, and 7 were identified to the generic level. Structure, ultrastructure, a species-specific immunofluorescent antibody test (IFAT), and PCR verified the identity of the Neoparamoeba sp. isolate. Five other genera of amoebae, comprising Platyamoeba, Mayorella, Vexillifera, Flabellula, and Nolandella, a scuticociliate of the genus Paranophrys, and a trypanosomatid (tranosomatid-bodonid incertae sedis) accompanied Neoparamoeba sp. in the gills.

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Advances in the knowledge of amphizoic amoebae infecting fish

Cited by 46 publications

References 84 publications

Influence of salmonid gill bacteria on development and severity of amoebic gill disease

Influence of salmonid gill bacteria on development and severity of amoebic gill disease

Fish-isolated Naegleria strains and their phylogeny inferred from ITS and SSU rDNA sequences

Neoparamoeba sp. and other protozoans on the gills of Atlantic salmon Salmo salar smolts in seawater

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