RESUMEN
Previous reports of the haplosporidian parasite Bonamia ostreae have been restricted to the Northern Hemisphere, including Europe, and both eastern and western North America. This species is reported for the first time in New Zealand infecting the flat oyster Ostrea chilensis. Histological examination of 149 adult oysters identified 119 (79.9%) infected with Bonamia microcells. Bonamia generic PCR of several oysters followed by DNA sequencing of a 300 bp portion of the 18S rDNA gene produced a 100% match with that of B. ostreae. All DNA-sequenced products also produced a B. ostreae PCR-restriction fragment length polymorphism (PCR-RFLP) profile. Bonamia species-specific PCRs further detected single infections of B. exitiosa (2.7%), B. ostreae (40.3%), and concurrent infections (53.7%) with these 2 Bonamia species identifying overall a Bonamia prevalence of 96.6%. Detailed histological inspection revealed 2 microcell types. An infection identified by PCR as B. ostreae histologically presented small microcells (mean ± SE diameter = 1.28 ± 0.16 µm, range = 0.9-2 µm, n = 60) commonly with eccentric nuclei. A B. exitiosa infection exhibited larger microcells (mean ± SE diameter = 2.12 ± 0.27 µm, range = 1.5-4 µm, n = 60) with more concentric nuclei. Concurrent infections of both Bonamia species, as identified by PCR, exhibited both types of microcells. DNA barcoding of the B. ostreae-infected oyster host confirmed the identification as O. chilensis. A suite of other parasites that accompany O. chilensis are reported here for the first time in mixed infection with B. ostreae including apicomplexan X (76.5%), Microsporidium rapuae (0.7%) and Bucephalus longicornutus (30.2%).
Asunto(s)
Haplosporidios/fisiología , Ostrea/parasitología , Animales , Interacciones Huésped-Parásitos , Nueva ZelandaRESUMEN
Haplosporidium patagon was found parasitizing Siphonaria lessonii and S. lateralis, 2 siphonariid gastropods co-occurring on the littoral rocky shore at Puerto Deseado, Santa Cruz, Argentina. Gastropods from 2 habitats representing 2 different levels of environmental harshness were studied. In both cases, S. lessonii showed a higher prevalence of infection (3.78%) over the entire 14 mo study period than S. lateralis (0.13%). Very different values of prevalence of infection were observed at the different sampling sites: Site 1, the more restrictive habitat (exposed for long periods to desiccation during low tides, higher ultraviolet exposure, and high ranges of temperature variation) showed a higher prevalence value (5.99%) than Site 2 (1.46%). Statistical differences in prevalence were also found between values corresponding to the austral spring (3.35% at Site 1 and 0.74% at Site 2) and winter (13.79% at Site 1 and 2.13% at Site 2). The presence/absence of H. patagon did not vary significantly with gastropod shell length. Infection affected the digestive gland, whose normal histology was greatly modified. The hermaphroditic gonads were also affected; the female germinal cells disappeared or only a few primary or previtellogenic oocytes were present, and vitellogenesis was inhibited. The function of the male germinal epithelium, as well as spermatogenesis and spermiogenesis processes and associated organs (seminal vesicles and seminal receptacles), were not affected. However, the glandular pallial complex of the reproductive systemwas affected, and we observed a significant reduction in development in parasitized gastropods. H. patagon sporocysts also invaded the supporting connective tissues of both the kidney and pseudobranch.
Asunto(s)
Gastrópodos/parasitología , Haplosporidios/fisiología , Animales , Argentina , Interacciones Huésped-Parásitos , Estaciones del Año , Factores de TiempoRESUMEN
Between 1995 and 1996, Bonamia exitiosa caused an epizootic in San Matías Gulf, Argentina, that spread from a commercial culture site of Ostrea puelchana to natural beds located at the northeastern coast of the gulf. A mortality rate of 95% was registered in cultured oysters, and oysters from natural beds were also affected. The aims of this study were to assess the parasite prevalence in oyster beds and the demographic structure 14 yr after the epizootic. Two different oyster beds were studied during 2009 and 2010. Parasite prevalence was studied related to oyster aggregation, density, sex, and oyster size. Prevalence reached 35.3% at Las Grutas and 18.9% at Banco Reparo and was proportionally associated with density. Prevalence was also associated with the type of aggregation in Banco Reparo, where carrier oysters were more infected. Infection was independent of sex category, and infected oysters were larger than the non-infected ones. Oyster density decreased markedly compared to previous studies in both beds and mean sizes were lower, while prevalence doubled. Because of the persistence of the beds in this period, disease seems to control the population structure.
Asunto(s)
Haplosporidios/fisiología , Ostrea/parasitología , Animales , Argentina , Océano Atlántico , Interacciones Huésped-Parásitos , Factores de TiempoRESUMEN
The advent of molecular detection assays has provided a set of very sensitive tools for the detection of pathogens in marine organisms, but it has also raised problems of how to interpret positive signals that are not accompanied by visual confirmation. PCR-positive results have recently been reported for Haplosporidium nelsoni (MSX), a pathogen of the oyster Crassostrea virginica in 31 of 40 oysters from 6 sites in the Gulf of Mexico and the Caribbean Sea. Histological confirmation of the PCR results was not undertaken, and no haplosporidian has been reported from the numerous histological studies and surveys of oysters in the region. To further investigate the possibility that H. nelsoni is present in this region, we sampled 210 oysters from 40 sites around the Gulf of Mexico and Puerto Rico using PCR and 180 of these using tissue-section histology also. None of the oysters showed evidence of H. nelsoni by PCR or of any haplosporidian by histology. We cannot, therefore, confirm that H. nelsoni is present and widespread in the Gulf of Mexico and the Caribbean Sea. Our results do not prove that H. nelsoni is absent from the region, but taken together with results from previous histological surveys, they suggest that for the purposes of controlling oyster importation, the region should continue to be considered free of the parasite.
Asunto(s)
Haplosporidios/fisiología , Ostreidae/parasitología , Animales , Interacciones Huésped-ParásitosRESUMEN
Oyster Ostrea chilensis samples were collected from Quihua Island, Chile, in December 2003 and February 2005, and examined in May 2004, and March, April and July 2005, for an ultrastructural comparison of the Chilean Bonamia sp. with other Bonamia spp. Only uni-nucleate stages were encountered, except in the July sample. The Chilean parasite differs from B. perspora in the apparent lack of a plasmodial stage and of sporulation. It resembles B. ostreae in size, the low number of mitochondrial profiles, and the prevalence and mean number of lipid droplets. It differs from B. ostreae in the greater prevalence of nuclear membrane-bound Golgi (NM-BG), associated haplosporogenesis, and smaller size of haplosporosomes. The Chilean Bonamia sp. resembles B. exitiosa in the number of haplosporosomes, prevalence of lipid droplets, anastomosing endoplasmic reticulum and NM-BG, presence of circles of smooth endoplasmic reticulum (sER), confronting cisternae (CC), and cylindrical CC (CCC). It also appears to have a similar developmental cycle to B. exitiosa with larger forms occurring in winter (August). The circles of sER, CC, and CCC have only been reported from B. exitiosa, and it appears that Chilean Bonamia sp. and B. exitiosa are more closely related than they are to B. perspora or B. ostreae. Similarities in ultrastructure and developmental stages between New Zealand and Chilean parasites suggest that the 2 species are related, and that the Chilean Bonamia sp. is either B. exitiosa, a sub-species of B. exitiosa, or a separate species closely related to B. exitiosa.