DAO 71:233-237 (2006)  -  doi:10.3354/dao071233

Ultrastructural description of new Rickettsia-like organisms in the commercial abalone Haliotis tuberculata (Gastropoda: Haliotidae) from the NW of Spain

Carlos Azevedo1,2,*, Ramón F. Conchas3, Jessica Tajdari2, Jaime Montes4

1Department of Cell Biology, Institute of Biomedical Sciences, University of Porto (ICBAS/UP), Lg. A. Salazar no. 2, 4099-003 Porto, Portugal
2Centre for Marine and Environmental Research, University of Porto (CIIMAR/UP), Rua dos Bragas no.177, 4050-123 Porto, Portugal
3Instituto Tecnolóxico para o Control do Medio Mariño de Galicia (INTECMAR), Consellería de Pesca e Asuntos Marítimos, Peirao de Vilaxoán, 36611 Vilagarcia de Arousa, Spain
4Centro de Investigacións Marinas (CIMA), Consellería de Pesca e Asuntos Marítimos, Pedras de Corón, 36620 Villanova de Arousa, Pontevedra, Spain

ABSTRACT: Rickettsia-like organisms (RLOs) were found in the commercially farmed abalone Haliotis tuberculata in the northwestern region of the Atlantic Coast of Spain and are described from light and transmission electron microscopy observations. The RLOs measured ~1.6 × 0.9 µm and were found in intracytoplasmic, spherical to ellipsoidal vacuoles (up to 8 µm) in the epithelial cells of the digestive diverticulae. The morphological ultrastructure of these organisms was typically prokaryotic, including a plasmalemma and a thin Gram-negative type cell wall. Several ultrastructural changes were observed in the epithelial cells of the host containing the RLOs. The nuclei became pycnotic and several basophilic dense inclusions appeared in the cytoplasm. In addition, the host cell appeared lysed and was ruptured in advanced stages of infection. It was impossible to ascertain whether the RLOs are responsible for this disease, as a haplosporidian infection was also present. We can only conclude that the presence of RLOs simultaneously with a haplosporidian parasite may contribute to the mortality of the abalone host.


KEY WORDS: Ultrastructure · Rickettsia-like organisms · Abalone · Spain


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