Presence of Marteilia Sp. (Paramyxea) in the Razor Clam Solen Marginatus (Pennántt, 1777) in Galicia (NW Spain)

Home , Solen (bivalve), Solen marginatus

Journal of Invertebrate Pathology 92 (2006) 109–111 www.elsevier.com/locate/yjipa Short communication Presence of Marteilia sp. (Paramyxea) in the razor clam Solen marginatus (Pennántt, 1777) in Galicia (NW Spain)

Carmen López ¤, Susana Darriba

Centro de Investigacións Mariñas (CIMA), Apartado 13, 36620, Vilanova de Arousa, Pontevedra, Spain

Received 30 January 2006; accepted 8 March 2006 Available online 21 April 2006

Abstract

Protistan parasites of the genus Marteilia, phylum Paramyxea, cause the molluscs disease named Marteiliosis. Histological observa- tions and transmission electron microscopy revealed the presence of life cycle stages of a Marteilia sp. in the bivalve mollusc Solen marginatus (Solenidae). Parasites occurred in epithelial cells of the digestive ducts and tubules. Early stages (primary cells) presented one or several nuclei while advances stages formed a complex of cells-within-cells (secondary and tertiary cells) culminating in spores. Refrin- gent bodies were present inside the presporangia. This is the Wrst report of a Marteilia sp. in S. marginatus. © 2006 Elsevier Inc. All rights reserved.

Keywords: Solen marginatus; Marteilia sp.; Marteiliosis; Protozoan parasite

Marteiliosis is a disease of molluscs caused by protistan sporulation. Life cycle stages of a parasite in the genus parasites of the genus Marteilia, phylum Paramyxea (Ber- Marteilia were found in histological sections during a path- the et al., 2000). The disease caused by Marteilia refringens ological study of Solen marginatus (Solenidae). This bivalve is currently listed by the OYce International des Epizooties mollusc is one of the three commercial razor clams in Gali- (OIE, 2005) as a notiWable disease. cia (NW Spain) and lives buried in Wne sand in the inter- In Europe, M. refringens was detected in Ostrea edulis tidal zone of low exposure beaches. causing mass mortalities (Grizel et al., 1974), in Ensis minor Samples of market-sized individuals of this razor clam (Ceschia et al., 2001), in Mytilus edulis and Mytilus gallo- (>80 mm in the longest axis) were taken every three months provincialis (Tigé and Rabouin, 1976; Villalba et al., 1993); during two years (from February 2003 until May 2005) Marteilia maurini parasitizes M. edulis and M. gallovprovin- from an intertidal natural bed in Ría de Arousa (Galicia, cialis (AuVret and Poder, 1983; Comps et al., 1982). Never- NW Spain). Samples were Wxed in Davidson’s and histolog- theless, there is controversy with the diVerentiation between ical sections were stained with Harris’ hematoxylin–eosin both species and host speciWcity (Le Roux et al., 2001; (H&E) for optical observation. Longshaw et al., 2001; López-Flores et al., 2004; Novoa The prevalence ranged from 16% (May 2005) to 38–42% et al., 2005; Villalba et al., 1993). Marteilia sp. was also (August 2003 and 2004) and the intensities were light and observed in cockles Cardium edule, clams Tapes rhomboides moderate, applying the scale of Villalba et al. (1993), only in and Tapes pullastra (Comps et al., 1975; Figueras et al., one month (August 2004) we found heavy intensity. These 1996; Poder et al., 1983). results suggest higher prevalence and intensities in summer. The key diagnostic features of the phylum Paramyxea Early stages (or primary cells) of the parasite observed in are the internal cleavage to produce cells within cells during the epithelial cells of the digestive ducts and tubules were eosinophilic, spherical or elongate in shape and uni- or mul- tinucleated (Fig. 1). More advanced developmental stages * Corresponding author. Fax: +34 986506788. including sporangia were observed in the same location, E-mail address: [email protected] (C. López). but were more abundant.

culminating in spores. The secondary cells (presporangia) were delimited by two membranes and contained the tertiary cells (spore primordia) which were 3.25 § 0.88 m in diameter (n D 15). Refringent bodies 0.58 § 0.11 m in diameter (n D 39) were present inside the presporangia. We observed up to 6 spores inside the sporangia. Mature spores were 3.74 § 0.46 m in diameter (n D 44) and presented 3 uninuclate sporoplasms or protoplasts (outermost, intermediate, and innermost) one inside the other. A spore nucleus was in the innermost sporoplasm. In the intermediate sporoplasm are present Xattened, vermiform, double membrane—limited vesicles 238 § 51 nm long and 61 § 9nm wide (n D 30). The outermost sporoplasm contains several spherical haplosporosomes 95 § 28 nm in diameter (n D 30). Spores were surrounded by a thickened wall (41.4 § 12.8 nm; n D 30). Ultrastructural results showed some diVerences to data of other authors (Longshaw et al., 2001; Renault et al., Fig. 1. Epithelium of the digestive tubule of the host (Solen marginatus) with early stage (arrow) and advanced stage (arrow heads) of Marteilia sp. 1995; Villalba et al., 1993). Refringent granules sizes in sporulation (H&E staining) (bar scale D 25 m). Marteilia sp. from S. marginatus were smaller than in M. refringens from M. galloprovincialis (2–6 m) (Villalba et al., 1993). Haplosporosomes in the outermost sporoplasm of spores in S. marginatus were always spherical not oblate as indicated by other authors (Villalba et al., 1993; Renault et al., 1995; Longshaw et al., 2001). The Xattened, vermiform, double membrane—limited vesicles into the intermediate sporoplasm were shorter and wider than results showed for M. refringens by Villalba et al. (1993). We want to emphasize that in this study the number of spores were 6 while the maximal number indicated in the bibliography for Marteilia spp. were 4 (Longshaw et al., 2001). This is the Wrst report of the Marteilia sp. presence in S. marginatus. Based on ultrastructural criteria, we cannot determine with certainty what species of Marteilia was found in S. marginatus. We found some diVerences between the other species described, but it will be desirable to com- plete this study with molecular techniques.

Acknowledgments

We are grateful to Jesus Méndez and Inés for ultrastructural techniques (CACTI- Vigo Univ.), to Dr. Azevedo, Fig. 2. Electron micrograph of sporangiosorus with four sporangia (Sg) Institute of Biomedical Sciences (Porto Univ.), for his com- containing refringent granules (RG) and spores (Sp) with three sporo- ments on the ultrastructural interpretation and to Elena plasms (O, outermost sporoplasm; M, intermediate sporoplasm; and I, Penas, Maribel Meléndez, and Mercedes Miranda for tech- innermost sporoplasm) (bar scale D 2 m). nical assistance for processing samples. W Small fragments of infected digestive gland were xed in References W 2.5% glutaraldehyde, post xed in 2% OsO4 and embedded in Epon. Sections were stained with uranyl acetate and lead AuVret, M., Poder, M., 1983. Recherches sur Marteilia maurini, parasite de citrate for ultrastructural study. The observation of ultra Mytilus edulis sur les côtes de Bretagne Nord. Revi. Trav. Inst. Pêches Wne sections by transmission electron microscopy (TEM) Mar. 47, 105–109. (Fig. 2) showed that the primary cells were delimited by a Berthe, F.C.J., Le Roux, F., Peyretaillade, E., Peyret, P., Rodríguez, D., plasmalemma containing multivesicullar bodies. The inter- Gouy, M., Vivarès, C.P., 2000. Marteiliosis in molluscs: a review. Aquat. Living Resour. 17, 433–448. nal cell enlarges and by a series of divisions formed a com- Ceschia, G., Zanchetta, S., Sello, M., Montesi, F., Figueras, A., 2001. plex of cells-within-cells (secondary and tertiary cells) Presenza di parassiti in cannolichi (Ensis minor and Ensis siliqua) C. López, S. Darriba / Journal of Invertebrate Pathology 92 (2006) 109–111 111

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