Ultrastructure of the aetiological agent of systemic granuloma in goldfish

Abstract

A fine structural investigation of the causative organisms of systemic granuloma in goldf~s h Carassius auratus revealed single-nucleate amoeboid organisms which were either intracellular, enclosed within a parasitophorous vacuole, or intercellular, embedded in an electron-dense matrix, presumably residues of defunct host cells. The nucleolemma-bound nucleus contained a large centrally positioned nucleolus. The cytoplasm contained ribosomal aggregates, endoplasmic reticulum and numerous adjunct thick-walled vesicles. Mitochondria were absent. Large cytoplasmic inclusions contained electron dense deposits. Additionally, cytoplasmic ribosome-rich bodies differentiated from the cytoplasm, segregating into an invagination of the organism's body wall and apparently were becoming confluent with the parasitophorous vacuole. The taxonomic and biological affinities of these organisms are discussed through comparison with similar Dermocystidium-like and amoeboid aetiological agents from fish.

Systemic granuloma observed in Atlantic salmon Salmo salar raised to market size in a freshwater recirculation aquaculture system

“…In gilthead sea bream Sparus aurata , systemic granuloma appears to be related to hypertyrosinaemia, and in chronically affected sea bream, which slowly become emaciated and die over 2–3 years, granulomatous lesions are eventually observed in all organs examined (Paperna ). Systemic granuloma has also been observed in goldfish Carassius auratus , although an infectious agent has been determined in this species (Paperna & Kim ; Pyecroft ). While widespread granulomatous inflammation has been described in Atlantic salmon Salmo salar in response to pathogenic agents, e.g.…”

The Class Mesomycetozoea: A Heterogeneous Group of Microorganisms at the Animal-Fungal Boundary

“…Owing to their morphological features, the Dermocystidium spp. were previously considered to be either members of the haplosporeans, the fungi, or the apicomplexa groups (9, 26,62,70,77,88,100).…”

Endolimax piscium sp. nov. (Amoebozoa), causative agent of systemic granulomatous disease of cultured sole, Solea senegalensis Kaup

“…The vacuole‐like structures surrounded by a bright concentric aureole are very similar to those described in the parasite causing systemic granulomatosis affecting goldfish (Dyková et al . ; Paperna & Kim ) and interpreted as endocytotic channels. Unfortunately, no invagination of the organism's body wall was observed in this work to verify this possibility, because E. piscium cells appeared rather smooth and only presented some slender filopodia‐like structures in the sectioned material.…”