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R Smolowitz

Publications and source records attributed to R Smolowitz.

8 recordsLinked to original sources
PubMed2006

DGGE-based detection method for Quahog Parasite Unknown (QPX).

Quahog Parasite Unknown (QPX) is a significant cause of hard clam Mercenaria mercenaria mortality along the northeast coast of the United States. It infects both wild and cultured clams, often annually in plots that are heavily farmed. Subclinically infected clams can be identified by histological examination of the mantle tissue, but there is currently no method available to monitor the presence of QPX in the environment. Here, we report on a polymerase chain reaction (PCR)-based method that will facilitate the detection of QPX in natural samples and seed clams. With our method, between 10 and 100 QPX cells can be detected in 1 l of water, 1 g of sediment and 100 mg of clam tissue. Denaturing gradient gel electrophoresis (DGGE) is used to establish whether the PCR products are the same as those in the control QPX culture. We used the method to screen 100 seed clams of 15 mm, and found that 10 to 12% of the clams were positive for the presence of the QPX organism. This method represents a reliable and sensitive procedure for screening both environmental samples and potentially contaminated small clams.

Animals↗
PubMed1998

Observations of a Protistan Disease Similar to QPX in Mercenaria mercenaria (Hard Clams) from the Coast of Massachusetts

During the summer and fall of 1995, in clam aquaculture leases at two locations on the coast of Massachusetts, significant mortalities were observed to occur primarily in 1½- to 2-year old hard clams (Mercenaria mercenaria, quahog) planted in the leases. Examination of hard clams from those leases suggested a parasite similar to QPX (Quahog Parasite Unknown), as described by Whyte, S. K., Cawthorn, R. J., and McGladdery, S. E. (1994, Can. Dis. Ag. Org. 19, 129-136), was responsible for the poor condition of affected clams and the resulting high mortality. In clam tissues, the QPX-like parasite formed thalli surrounded by a mucofilamentous net. Larger thalli underwent endosporulation producing sporangia that contained approximately 40 endospores. Rupture of the sporangium released the endospores into the surrounding tissue. Inflammatory response by the clam to infection was chronic, active, and granulomatous. The occurrence both of phagocytic multinucleated giant inflammatory cells and inflammatory encapsulation of parasites were commonly identified as part of the response. Moderately to severely infected clams showed significantly reduced growth and a poorer condition index as compared to uninfected or mildly infected clams. Copyright 1998 Academic Press. Copyright 1998 Academic Press

Journal Article↗
PubMed1992

Cytochrome P450IA1 in hepatic lesions of a teleost fish (Fundulus heteroclitus) collected from a polycyclic aromatic hydrocarbon-contaminated site.

The expression of cytochrome P450IA1 was examined in hepatic lesions of mummichog (Fundulus heteroclitus), a small, non-migratory teleost fish collected from a site in the Elizabeth River, VA, heavily contaminated with polycyclic aromatic hydrocarbons (PAH) of creosote origin. Immunoblot ('Western' blot) analysis using monoclonal antibody (MAb 1-12-3) to P450IA1 of the marine fish Stenotomus chrysops indicated that cytochrome P450IA1 levels in hepatocellular carcinoma and in foci of cellular alteration were 28-85% lower than those of adjacent non-neoplastic tissue. P450IA1-dependent monooxygenase activity, measured as ethoxyresorufin O-deethylase (EROD), exhibited a similar trend with EROD activity in lesions being 15-77% lower than activity in non-neoplastic tissue. Immunohistochemical examination of liver sections revealed general low intensity P450IA1-associated staining in hepatocellular carcinoma, exocrine pancreatic tissue, bile ducts and cholangiocellular proliferative lesions. Staining intensity of non-neoplastic hepatic parenchyma varied considerably and was focally distributed. In one case intense staining was observed in an altered hepatocellular focus (putative preneoplastic lesion). The results indicate important similarities in the expression of P450IA1 in neoplasms of fish and mammals and suggest an adaptive response of a wild population to carcinogen exposure.

Animals↗