Characterization of actin genes in Bonamia ostreae and their application to phylogeny of the Haplosporidia

The flat oyster Ostrea edulis L. is widespread along the Italian coasts. In particular, the Manfredonia Gulf (Adriatic Sea) represents an important site where natural beds subsist. Previous monitoring conducted in 1990 by light microscopy and ultrastructural studies revealed the presence of Bonamia-like microcell parasites in some flat oysters: following this observation, a new sampling of O. edulis was carried out at this location in 2007. Of 750 oysters collected, 3 showed the presence of uninucleated microcells (2 to 3 µm diameter) free or inside the haemocyte cytoplasm by cytology and histopathology. Molecular analysis confirmed that the microcells in 2 oysters were B. exitiosa, whereas in the third oyster the microcells were B. ostreae. Moreover, molecular studies were carried out to confirm the existence of Bonamia sp. in archived samples, confirming the presence of B. ostreae in the Manfredonia Gulf since 1990. KEY WORDS: Bonamia spp. · Ostrea edulis · Molecular analysis · Electron microscopy Resale or republication not permitted without written consent of the publisherDis Aquat Org 89: [79][80][81][82][83][84][85] 2010 Bonamia exitiosa infects Ostrea chilensis in New Zealand (Hine et al. 2001) and O. angasi in Australia (Corbeil et al. 2006) and has been recently reported in O. edulis in Spain (Abollo et al. 2008). B. roughleyi, previously called Mikrocytos roughleyi, infects Saccostrea glomerata in southeast Australia (Farley et al. 1988). B. perspora is a newly described protozoan species found in Ostreola equestris (North Carolina, USA) and represents the first Bonamia species producing a typical haplosporidian spore (Carnegie et al. 2006). Other B. exitiosa-like organisms have been described in O. chilensis from Chile (Kern 1993, Campalans et al. 2000, O. puelchana from Argentina (Kroeck & Montes 2005), and Crassostrea ariakensis from North Carolina ); these organisms have been subsequently declared B. exitiosa (Lopez-Flores et al. 2007).Previous studies have reported by microscopic and ultrastrustural means the occurrence in Italy of small parasites similar to Bonamia sp. in flat oysters collected from the southern (Tiscar et al. 1991) and northern Adriatic Sea (Tiscar et al. 2002). A small number of molluscs appeared infected by the parasites (1/161 from the southern and 8/600 from the northern Adriatic Sea, respectively). Nevertheless all the infected oysters showed high infection level of the haemocytes with the presence of numerous protozoans per cell (Tiscar et al. 1991(Tiscar et al. , 2002.Taking into account these previous reports, the aim of the present study was to investigate by cytology and histology the occurrence of microcell parasites in flat oysters Ostrea edulis newly collected from natural beds in the southern Adriatic Sea and to characterize the recovered parasites by molecular and ultrastructural analyses as well as to confirm and characterize the presence of Bonamia sp. in one positive sample collected during 1990 from the Manfredonia Gulf (Tiscar et al. 1991). MAT...

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Detection of Bonamia ostreae and B. exitiosa (Haplosporidia) in Ostrea edulis from the Adriatic Sea (Italy)

Narcisi¹,

Arzul²,

Cargini³

et al. 2010

“…and Minchinia spp. The relationship with the latter and H. costale has recently been supported in phylogenies based on actin gene sequences (López-Flores et al 2007), and on a prawn haplosporidian (Nunan et al 2007). Future studies may confirm the placing of crustacean haplosporidians close to or between Bonamia spp.…”

Section: Haplosporogenesismentioning

confidence: 71%

Inter-relationships of haplosporidians deduced from ultrastructural studies

Hine¹,

Carnegie²,

Burreson³

et al. 2009

We reviewed papers reporting haplosporidian ultrastructure to compare inter-relationships based on ultrastructure with those based on molecular data, to identify features that may be important in haplosporidian taxonomy, and to consider parasite taxonomy in relation to host taxonomy. There were links between the following: (1) the plasmodia of an abalone parasite, Haplosporidium nelsoni and Urosporidium crescens in the release of haplosporosomes; (2) H. costale and H. armoricanum in haplosporosome shape and presence and shape of Golgi in spores; (3) basal asporous crustacean haplosporidians which form haplosporosomes from formative bodies (FBs) in vegetative stages -H. nelsoni, which forms haplosporosomes from FBs in plasmodial cytoplasm, and H. louisiana, Minchinia spp. and Bonamia perspora, which form haplosporosomes from FBs in spores; (4) crustacean haplosporidians, Bonamia spp. and M. occulta in the predominance of uni-and binucleate stages; and (5) lipid-like vesicles in sporoplasms of H. costale, H. armoricanum, H. lusitanicum, H. pickfordi, H. montforti, and B. perspora. In general, these relationships reflect phylogenies based on molecular studies. As well as spore form and ornamentation, haplosporogenesis in spores appears to be taxonomically important. Parasite and host taxonomy were linked in the infection of lower invertebrates by Urosporidium spp., the infection of oysters by Bonamia spp., and of molluscs by Minchinia spp. Haplosporidium spp. are patently an artificial, paraphyletic group probably comprising many taxa. Consequently, the taxonomy of haplosporidians needs a thorough revision.

“…are parasites of bivalve hosts, and currently 4 species are recognised in the genus, namely B. ostreae, B. exitiosa, B. perspora and B. roughleyi (Pichot et al 1980, Cochennec-Laureau et al 2003, Reece et al 2004, Carnegie et al 2006, López-Flores et al 2007. With the exception of B. perspora, these normally occur within haemocytes of the host (Cochennec-Laureau et al 2003); B. perspora occurs within connective tissues of its host Ostreola equestris (Carnegie et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Detection of Bonamia exitiosa (Haplosporidia) in European flat oysters Ostrea edulis cultivated in mainland Britain

Longshaw¹,

Stone²,

Wood³

et al. 2013

Following a reported mortality event of European flat oysters Ostrea edulis in southwestern England in December 2010, a sample of 30 oysters was examined using histology and molecular techniques. Histological examination of the oysters revealed the presence of microcell stages in the haemocytes and connective tissues of 3 out of the 30 animals examined. One animal showing marked haemocyte infiltration of the connective tissues was considered to be infected with Bonamia ostreae based on the presence of small uninucleate microcells measuring approximately 1 to 1.5 µm in diameter. Two other oysters were considered by histology to be infected with B. exitiosa. Infected haemocytes contained up to 5 microcells, measuring approximately 2 to 3 µm in diameter with a central or subcentral nucleus. Rarely, larger plasmodia-like multinucleated stages were noted in the haemocyte cytoplasm characterised by its irregular shape and increased eosinophilic cytoplasm. Haemocyte infiltration of the connective tissues surrounding the digestive gland and the mantle was noted along with necrosis of the tissues associated with the infection. Molecular analysis of the infected animals confirmed the presence of B. exitiosa in the sample. This study describes the parasite from flat oysters cultured in the UK; subsequent targeted sampling has not detected the parasite in flat oyster populations at this or other sites within the UK.