Prokaryote infections in the New Zealand scallops Pecten novaezelandiae and Chlamys delicatula

This paper reports the results of the survey developed after the first detection of protozoan Marteilia sp. infection of the grooved razor shell Solen marginatus (Pulteney, 1799) from Galicia (NW Spain) in 2006. Furthermore, we analysed other parasites and pathological conditions found in grooved razor shell populations throughout this survey, such as metacercariae of trematodes, prokaryotic infections and disseminated neoplasms, some of which could cause moderate or severe damage to the host depending on the intensity of infection. A total of 17 natural beds distributed along the Galician coast were analysed, and Marteilia sp. was detected in 6 of them with low prevalence, moderate intensity and no negative effects over the populations.KEY WORDS: Grooved razor shell · Prokaryote · Protozoa · Metacercaria · Disseminated neoplasm · Histopathological survey Resale or republication not permitted without written consent of the publisherDis Aquat Org 112: [177][178][179][180][181][182][183][184] 2015 Villalba et al. 2014). In fact, infection by M. refringens is a notifiable disease listed by the World Organisation for Animal Health (2013) and under European legislation (Directive 2006/88). The aim of the present study was to survey for Marteilia sp. in S. marginatus and to characterize other parasites and pathological conditions affecting grooved razor shell along the Galician coast. MATERIALS AND METHODSSamples of 20 to 30 commercial grooved razor shells (> 80 mm length) were collected by hand using salt (spread in burrow entrances, causing the razor shells to leave the burrow) in 17 intertidal beds in northern and western rías along the Galician coast ( Fig. 1). Samplings were conducted seasonally, during the years 2008 to 2011 (previous data from the Redondela bed between the years 2006 and 2008 were also included), except in the Barraña and Mañóns beds, where samples were collected monthly and in the Cariño bed, where they were collected every 2 mo.In the laboratory, valves were separated, and gills, mantle and visceral mass were examined macroscopically for evidence of macroparasites, lesions, abnormal colouration and other malformations. A section including digestive gland, gonad, kidney, foot, mantle lobes, labial palps and gills was taken from every specimen, fixed in Davidson's solution (Shaw & Battle 1957) and embedded in paraffin. Paraffin blocks were sectioned at 5 µm with a rotary microtome. Tissue sections were deparaffinised, stained with Harris' haematoxylin and eosin and examined by light microscopy for symbionts and pathological conditions such as haemocyte infiltrations and neoplasms.To further characterize the prokaryotic colonies detected in histology sections stained with Harris' haematoxylin and eosin, additional staining techniques were used: Gram's Brown and Hopps method for Gram-positive and Gram-negative bacteria, the Pinkerton method for rickettsial organisms, the Ziehl-Neelsen method for acid-fast bacteria and the Feulgen method for DNA (Howard & Smith 1983).Some samples we...

Section: Colonies Of Intracellular Prokaryotic-like Organisms (Ipo) Isupporting

confidence: 58%

supporting

confidence: 61%

Marteilia sp. and other parasites and pathological conditions in Solen marginatus populations along the Galician coast (NW Spain)

Ruiz¹,

Darriba²,

Rodríguez³

et al. 2015

“…The major disease-causing agents found in bivalve tissues are bacteria, rickettsiae, mycoplasmas and protozoan species, all of which can sometimes cause the death of the host (Lauckner 1983, Elston & Peacock 1984, Azevedo & Villalba 1991, Azevedo 1993, Bower et al 1994, Renault & Cochennec 1995, Chen et al 2000, Hine & Diggles 2002. Of the protozoans, coccidian parasites have been found in different organs of aquatic animals, causing significant pathology and mortalities (Lauckner 1983, Bower et al 1994, Gestal et al 1999.…”

Section: Introductionmentioning

confidence: 99%

Ultrastructural description of an unidentified -apicomplexan oocyst containing bacteria-like hyperparasites in the gill of Crassostrea rizophorae

Azevedo¹,

Padovan²,

Corral³

et al. 2005

Oocysts of an unidentified coccidian are reported in this study to parasitize the gills of the oyster Crassostrea rizophorae (Mollusca, Bivalvia) collected near the city of Recife (Itamaracá Island, 07°38' 00'' S, 34°48' 06'' W), Brazil. Oocysts appeared as light and dense forms, both containing rod-shaped, bacteria-like hyperparasites (BL). Both light and dense oocysts were spherical, 4.3 to 4.7 µm in diameter, but denser oocysts had irregular contours. Both forms consisted of a thick dense wall (~165 nm thick) consisting of 3 layers. The outermost, a dense and irregular layer about 25 nm thick, possessed numerous bead-like structures and some slender conical projections (up to 1.5 µm long). The inner layer of the wall was formed by a dense and homogenous layer about 125 nm thick. Between these 2 layers, a thin light layer about 12 nm thick was present. Uninucleated sporocysts occupied the internal space of the oocyst and contained some rod-shaped BL and mitochondria surrounded by numerous ribosome-like particles. The dense forms of the oocysts showed the same structures described in the lighter forms and appeared to be the final maturation form of the oocysts. Free sporozoites were occasionally observed among oocysts. MATERIALS AND METHODSOysters Crassostrea rizophorae Guilding, 1826 (Mollusca, Bivalvia) were collected from Itamaracá Island (07°38' 00'' S 34°48' 06'' W), near the city of Recife on the Northeastern Atlantic coast of Brazil. This work is part of a health program concerned with the aquatic fauna of this region. Small fragments of parasitized fresh gills containing numerous oocysts were observed under a light microscope and photographed using Nomarski differential interferencecontrast (DIC) optics. Measurements were made directly on living oocysts or by means of photomicrographs obtained from living oocysts. For transmission electron microscopy (TEM), small fragments of the infected gills were fixed in 3.0% glutaraldelyde in 0.2 M sodium cacodylate buffer for 10 h at 4°C, washed overnight in the same buffer at 4°C, and then postfixed in buffered 2.0% osmium tetroxide for 3 h at the same temperature. After dehydration in a graded ethanol series and propylene oxide, the fragments of infected gills were embedded in Epon. Semithin sections were stained with methylene blue-Azur II and the ultrathin sections were double-stained with uranyl acetate and lead citrate, and observed in a JEOL 100CXII TEM, operated at 60 KV.Infected gill fragments from oysters were aseptically removed and incubated in the filtered seawater at 20°C, without antibiotics, for 7 to 10 d in order to observe whether oocysts become liberated from the surrounding tissues. RESULTS Light microscopic studiesA protist represented by walled oocysts in the gill of Crassostrea rizophorae was observed in fresh squash preparations under light microscopy ( Fig. 1). Isolated or grouped oocysts were irregularly dispersed in the sub-epithelial gill tissues (Figs. 2 & 3). In semithin sections it was observed that some irregular oocysts ...

“…Amongst them, rickettsiae and rickettsia-like organisms (RLOs) have been reported infecting several aquatic animal groups, mainly bivalves (Harshbarger et al 1977, Buchannan 1978, Elston 1986, Mialhe et al 1987, Azevedo & Villalba 1991, Renault & Cochennec 1994, Gardner et al 1995, Wu & Pan 1999, Antonio et al 2000, Hine & Diggles 2002, Azevedo et al 2005. These microorganisms are small, pleomorphic, rod-shaped coccoid prokaryotes, most of which are obligate intracellular Gram-positive parasites (Sparks 1985).…”

Section: Introductionmentioning

confidence: 99%

“…These microorganisms are small, pleomorphic, rod-shaped coccoid prokaryotes, most of which are obligate intracellular Gram-positive parasites (Sparks 1985). Some RLOs have been associated with diseases and mortality in molluscs (Azevedo & Villalba 1991, Haaker et al 1992, Wu & Pan 1999, Hine & Diggles 2002. A lethal disease known as '(foot) withering syndrome', characterised mainly by atrophy of the foot muscle, has been associated with mass mortalities in cultured and natural populations of Haliotis spp.…”

Section: Introductionmentioning

confidence: 99%

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

Azevedo¹,

Conchas²,

Tajdari³

et al. 2006

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 Resale or republication not permitted without written consent of the publisherDis Aquat Org 71: [233][234][235][236][237] 2006 cultured and natural populations of Haliotis spp. from different geographic areas (Antonio et al. 2000, Bower 2004. Recently, the syndrome has been described as a severe pathogen-caused disease associated with Rickettsiales-like prokaryotes (Haaker et al. 1992, Gardner et al. 1995, Antonio et al. 2000, Bower 2004, Braid et al. 2005.The purpose of this work is to document and describe the ultrastructure of RLOs found in abalone Haliotis tuberculata. These prokaryotic parasites may contribute to the mortality of this commercially important species. MATERIALS AND METHODSJuvenile abalone Haliotis tuberculata (Linnaeus, 1758) (Gastropoda: Haliotidae) from Ireland were grown in barrels suspended from rafts in El Grove, Galicia, NW of Spain (42°29' 20'' N, 08°53' 56'' W). Fifteen specimens were observed by light microscopy (LM) during a study which aimed to identify haplosporidiosis. In addition to the haplosporidian parasite, some of the specimens were also found to be parasitized by RLOs, mainly in the epithelial cells of the digestive diverticulae.Small fragments of the parasitized tissues were fixed in 3% glutaraldehyde in 0.2 M sodium cacodylate buffer pH 7.2 for 10 h at 4°C, washed overnight in the same buffer at 4°C, and post-fixed in buffered 2% OsO 4 for 3 h at 4°C. After dehydration in an ascendant ethanol series followed by propylene oxide, the tissues were embedded in Epon. Semithin sections were stained with methylene blue-Azur II and observed under differential interference contrast (DIC; Nomarski) microscopy. For transmission electron microscopy (TEM), the tissues were ultrathin-sectioned with a diamond knife, double-stained with uranyl acetate and lead citrate and observed in a JEOL 100CXII TEM operat...