St-Jean Sylvie D.

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St-Jean
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Sylvie D.
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  • Preprint
    Identification and phylogenetic comparison of p53 in two distinct mussel species (Mytilus)
    ( 2005-02-10) Muttray, Annette F. ; Cox, Rachel L. ; St-Jean, Sylvie D. ; van Poppelen, Paul ; Reinisch, Carol L. ; Baldwin, Susan A.
    The extent to which humans and wildlife are exposed to anthropogenic challenges is an important focus of environmental research. Potential use of p53 gene family marker(s) for aquatic environmental effects monitoring is the long-term goal of this research. The p53 gene is a tumor suppressor gene that is fundamental in cell cycle control and apoptosis. It is mutated or differentially expressed in about 50% of all human cancers and p53 family members are differentially expressed in leukemic clams. Here, we report the identification and characterization of the p53 gene in two species of Mytilus, Mytilus edulis and Mytilus trossulus, using RT-PCR with degenerate and specific primers to conserved regions of the gene. The Mytilus p53 proteins are 99.8% identical and closely related to clam (Mya) p53. In particular, the 3′ untranslated regions were examined to gain understanding of potential post-transcriptional regulatory pathways of p53 expression. We found nuclear and cytoplasmic polyadenylation elements, adenylate/uridylate-rich elements, and a K-box motif previously identified in other, unrelated genes. We also identified a new motif in the p53 3′UTR which is highly conserved across vertebrate and invertebrate species. Differences between the p53 genes of the two Mytilus species may be part of genetic determinants underlying variation in leukemia prevalence and/or development, but this requires further investigation. In conclusion, the conserved regions in these p53 paralogues may represent potential control points in gene expression. This information provides a critical first step in the evaluation of p53 expression as a potential marker for environmental assessment.
  • Article
    Detecting p53 family proteins in haemocytic leukemia cells of Mytilus edulis from Pictou Harbour, Nova Scotia, Canada
    (National Research Council Canada, 2005-09-01) St-Jean, Sylvie D. ; Stephens, Raymond E. ; Courtenay, S. C. ; Reinisch, Carol L.
    Evaluating patterns of expression of p53-related proteins in cells is a novel approach in defining environmentally linked diseases. We have examined the induction of haemocytic leukemia in Mytilus edulis by municipal and industrial contaminants in Pictou Harbour, Nova Scotia, Canada. We used a murine monoclonal antibody, 1E10, as a diagnostic reagent to detect leukemic cells. We first characterized the reactivity of 1E10 with both normal and leukemic Mytilus haemocytes by confocal microscopy. We then compared p53 gene family expression (p53, p63–p73, and p97) in normal versus leukemic haemocytes using a panel of monoclonal and polyclonal antibodies to p53 family proteins. The immunochemical data demonstrate that haemocytic leukemia cells of M. edulis differentially express p63–p73 and p97–p120 proteins. We subsequently used 1E10 to diagnose haemocytic leukemia in 500 M. edulis previously deployed 6 months earlier in Pictou Harbour. In the field, Mytilus caged near untreated municipal wastewater and bleached kraft pulpmill effluents have a significantly greater chance of developing haemocytic leukemia than do mussels exposed to reference sites.