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Biomedical subjects

N J Blake

Publications and source records attributed to N J Blake.

9 recordsLinked to original sources
PubMed1993

Implications for the presence of transforming genes in gonadal tumors in two bivalve mollusk species.

Studies were initiated on oncogene activation in two bivalve species with high frequencies of histologically identifiable gonadal neoplasms. Pathological assessments identified epizootic seminomas and dysgerminomas in softshell clams (Mya arenaria) from three Maine estuarine sites contaminated by herbicides and in hardshell clams (Mercenaria) from the Indian River in Florida, an area of potential citrus agrochemical exposure. NIH3T3 transfection assays were used to examine DNA isolated from these molluscan tumors for the presence of activated oncogenes. DNAs isolated from advanced tumors in both species were able to transform NIH3T3 cells in a standard focus assay. These same cells were also able to form colonies in low concentrations of serum and induce tumors in athymic mice. Cells expanded from isolated foci demonstrated anchorage-independent growth in soft agar. The results of these studies indicate that DNA from the clam tumors is able to transform mouse fibroblasts, which suggests that a transforming gene is present in these tumor cells. Studies are under way to identify the gene(s) detected by these assays.

3T3 Cells↗
PubMed1987

Larval Sulcascaris sulcata from calico scallops, Argopecten gibbus, along the southeast coast of the United States.

Adductor muscles of calico scallops, Argopecten gibbus, collected off the southeastern coast of the United States from May 1982 to December 1984 were examined for the presence of larvae of the parasitic nematode, Sulcascaris sulcata. Infection intensity, prevalence, and larval length were all positively correlated (P less than 0.001) with scallop shell height (age). Prevalence was generally highest in December and lowest in August as a result of yearly trends in the age structure of the scallop population. Prevalence was not influenced by latitude or depth over the ranges examined. The rate of infection of marine molluscs by S. sulcata is generally related to the degree and length of exposure to third-stage larvae, whose distribution is essentially that of the marine turtle definitive host. Thus, over the wide geographic area of the east coast of the U.S., overall rates of infection decrease with increasing latitude.

Animals↗
PubMed1983

Relationship among fecal coliforms, Escherichia coli, and Salmonella spp. in shellfish.

The relationship of fecal coliforms, Escherichia coli, and Salmonella spp. was examined in freshly harvested and stored shellfish. In 16 of 40 freshly collected oyster samples, fecal coliform levels were above the recommended wholesale level suggested by the National Shellfish Sanitation Program (less than or equal to 230/100 g), and Salmonella spp. were present in three of these samples. Salmonella spp. were not, however, present in any sample containing less than 230 fecal coliforms per 100 g. Analysis of the data suggests that low fecal coliform levels in both fresh and stored oysters are good indicators of the absence of Salmonella spp., but that high levels of fecal coliforms are somewhat limited in predicting the presence of Salmonella spp. E. coli levels correlated very strongly with fecal coliform levels in both fresh and stored oysters and clams, suggesting that there is no advantage in replacing fecal coliforms with E. coli as an indicator of shellfish quality.

Animals↗
PubMed1983

Effects of storage on microbial loads of two commercially important shellfish species, Crassostrea virginica and Mercenaria campechiensis.

The effects of storage on the microbial load in two commercially important species of shellfish were examined. Oysters (Crassostrea virginica) were stored as shellstock, shucked meats, and fully processed meats at four temperatures for up to 21 days, and clams (Mercenaria campechiensis) were stored only as shellstock. The concentrations of most microbiological groups of organisms increased with the duration and temperature of storage in both shellfish species, although the increases were significantly lower in claims. Concentrations of Vibrio cholerae rose by approximately 1 log in oysters stored as shellstock after 7 days at 2 degrees C, and Lac+ vibrios increased 2 logs at 8 degrees C. Total counts of bacteria, fungi, coliforms, fecal streptococci, Aeromonas hydrophila, and clostridia were significantly higher in shucked oysters than in those stored as shellstock. Fecal coliforms were statistically the same, but V. cholerae, Vibrio parahaemolyticus, and the Lac+ vibrios were higher in oysters stored as shellstock. The concentrations of all microbial groups were higher in fully processed oysters than in shucked meats, with the exception of the vibrios, which showed no significant difference among the treatments. The results showed that although traditional methods of storing shellfish resulted in an overall increase in the microbial load, vibrio levels increased only in oysters stored as shellstock. Although fecal coliform and total bacterial counts did not correlate with those for vibrios in fresh oysters, strong correlations were observed in oysters stored for 7 days, suggesting that these indicators may be useful in monitoring oyster quality when meats are stored for a limited time as shellstock.

Aeromonas↗
PubMed1982

Isolation and characterization of Vibrio vulnificus from two Florida estuaries.

Vibrio vulnificus was enumerated in seawater and shellfish from two Florida estuaries at selected seasonal intervals. There were significant fluctuations in the presence and numbers of V. vulnificus. Relatively high seawater temperature and salinity favored the presence of V. vulnificus in both seawater and shellfish samples.

Animals↗