| isolation and 18s ribosomal dna gene sequences of marteilioides chungmuensis (paramyxea), an ovarian parasite of the pacific oyster crassostrea gigas. | to develop sensitive detection techniques with the aim of elucidating the life cycle of marteilioides chungmuensis, an intracellular paramyxean infecting the ovary of the pacific oyster crassostrea gigas, we isolated the parasite at the sporont stage from infected oysters using a freeze-thaw procedure at -20 degrees c and differential centrifugations in discontinuous sucrose and percoll gradients. dna was extracted from the isolated sporonts, and a pcr amplicon of 18s small subunit ribosomal rna ... | 2003 | 12747642 |
| prevalence and infection intensity of the ovarian parasite marteilioides chungmuensis during an annual reproductive cycle of the oyster crassostrea gigas. | the occurrence of marteilioides chungmuensis, a protozoan paramyxean parasite in the reproductive system of the pacific oyster crassostrea gigas, was observed at gosung bay, korea. seasonal variation in gonad development was investigated in a suspended cultured oyster population. gametogenesis began in february and first-spawning was observed between mid and late june when surface water temperature reached 22 to 25 degrees c. spawning activity extended from mid june to late september, with 2 mar ... | 2003 | 14667038 |
| an ovarian infection in the iwagaki oyster, crassostrea nippona, with the protozoan parasite marteilioides chungmuensis. | | 2004 | 15139910 |
| early developmental stages of a protozoan parasite, marteilioides chungmuensis (paramyxea), the causative agent of the ovary enlargement disease in the pacific oyster, crassostrea gigas. | a paramyxea, marteilioides chungmuensis, causes the irregular enlargement of the ovary in the pacific oyster, crassostrea gigas in korea and japan. the knowledge about the life cycle of the parasite has been limited to the sporulation stages within the oocyte of oysters. in this study, we used the parasite-specific dna probes and electron microscopy to experimentally infected oysters in a field and successfully clarified early developmental stages of the parasite. the parasite invaded the oyster ... | 2004 | 15380684 |
| relationship between marteilioides chungmuensis infection and reproduction in the pacific oyster, crassostrea gigas. | marteilioides chungmuensis, a protozoan paramyxean parasite, infects the oocytes of the pacific oyster, crassostrea gigas. the effects of infection on the reproductive cycle of c. gigas were investigated over two consecutive years at okayama prefecture, japan. in male oysters, gonadal development began during february/march, maturity was achieved in june and spawning activity extended from july to september. in november and december, male oysters were not seen, probably because their gonads regr ... | 2007 | 17643446 |
| pathogenicity of the protozoan parasite marteilioides chungmuensis in the pacific oyster crassostrea gigas. | marteilioides chungmuensis is an ovarian parasite that causes nodule-like structures to appear on the gonads of female pacific oysters, crassostrea gigas. it is known that the prevalence of infection increases in summer and decreases from autumn to spring. to investigate the decrease in prevalence of infection and pathogenicity of the parasite, a biopsy method was developed to detect infected oysters, which were then monitored to calculate the mortality rate. mortality of infected oysters was re ... | 2008 | 17697680 |
| seasonality in the infection and invasion of marteilioides chungmuensis in the pacific oyster crassostrea gigas. | the protozoan parasite marteilioides chungmuensis causes irregular enlargement of the ovary in the pacific oyster crassostrea gigas. the parasite invades the oyster through the epithelial tissue of the labial palp, replicates in the connective tissue, and then moves to the gonad, producing spores inside the oocytes. in this study the seasonality and invasion period of the parasite into the host was investigated over a 1 yr cycle. uninfected 1 and 0 yr old (spat) oysters were placed in an epizoot ... | 2008 | 18717068 |
| Non-specific defensive factors of the Pacific oyster Crassostrea gigas against infection with Marteilioides chungmuensis: a flow-cytometric study. | In order to assess changes in the activity of immunecompetency present in Crassostrea gigas infected with Marteilioides chungmuensis (Protozoa), the total hemocyte counts (THC), hemocyte populations, hemocyte viability, and phagocytosis rate were measured in oysters using flow cytometry. THC were increased significantly in oysters infected with M. chungmuensis relative to the healthy appearing oysters (HAO) (P<0.05). Among the total hemocyte composition, granulocyte levels were significantly inc ... | 2011 | 22072822 |
| detection of a parasitic amoeba (order dactylopodida) in the female gonads of oysters in brazil. | the impacts of oocyte parasites on the reproductive success of molluscs are largely unknown. in this study, we evaluated the presence of gonad parasites in 6 species of marine bivalve molluscs native to southern brazil. cultured bivalves included the mangrove oyster crassostrea gasar (sometimes called c. brasiliana), the brown mussel perna perna, the lion's paw scallop nodipecten nodosus and the wing pearl oyster pteria hirundo. another species of mangrove oyster, c. rhizophorae, and the carib p ... | 2014 | 24991850 |
| molecular and histological identification of marteilioides infection in suminoe oyster crassostrea ariakensis, manila clam ruditapes philippinarum and pacific oyster crassostrea gigas on the south coast of korea. | the oyster ovarian parasite marteilioides chungmuensis has been reported from korea and japan, damaging the oyster industries. recently, marteilioides-like organisms have been identified in other commercially important marine bivalves. in this study, we surveyed marteilioides infection in the manila clam ruditapes philippinarum, suminoe oyster crassostrea ariakensis, and pacific oyster crassostrea gigas, using histology and marteilioides-specific small subunit (ssu) rdna pcr. the ssu rdna sequen ... | 2013 | 24018168 |
| a study of diagnostic methods for marteilioides chungmuensis infections in the pacific oyster crassostrea gigas. | the eggs of the pacific oyster, crassostraea gigas, become infertile when infected by the parasite marteilioides chungmuensis. histologically, m. chungmuensis infects the oyster oocyte cytoplasm, and the ovaries take on a "lumpy" appearance once infected, which lowers commercial value of the oyster. this has a negative economic impact on oyster farms in south korea and japan. in this study, we compared traditional diagnostic methods (histology) with two molecular-based methods (polymerase chain ... | 2012 | 22634519 |