Reverse transcriptase activity associated with haemic neoplasia in the soft-shell clam Mya arenaria

• Published in: Diseases of aquatic organisms Vol. 84; no. 1; pp. 57 - 63
• Main Authors: ABOELKHAIR, M, SIAH, A, CLARK, K. F, MCKENNA, P, PARISEAU, J, GREENWOOD, S. J, BERTHE, F. C. J, CEPICA, A
• Format: Journal Article
• Language: English
• Published: Oldendorf Inter-Research 09.03.2009
• Subjects: Animal aquaculture; Animal productions; Animals; Biological and medical sciences; Bivalvia - virology; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Viral - physiology; Hematologic Diseases - veterinary; Hematologic Diseases - virology; Invertebrate aquaculture; Invertebrates; Mollusca; Neoplasms - enzymology; Pathology; Retroviridae - classification; Retroviridae - metabolism; RNA-Directed DNA Polymerase - metabolism; Edible mollusc; Polyploidy; Reverse transcriptase; Disease; Hemolymph; Method; Product-enhanced reverse transcriptase assay; Tetraploidy; Virus; PERT; Enzymatic activity; Taqman; Bivalvia; Mya arenaria; Haemic neoplasia; Diagnosis; Invertebrata; Mollusca; Cell
• ISSN: 0177-5103; 1616-1580
• DOI: 10.3354/dao02038

Reverse transcriptase (RT) activity has been reported in bivalves affected by haemic neoplasia (HN). Since all retroviruses have RT, detection of RT activity was regarded as evidence for the retroviral etiology of HN. This study investigates the relationship between RT levels and the progress of HN as indicated by percentages of tetraploid cells in soft-shell clams Mya arenaria. The percentages of tetraploid cells were estimated by flow cytometry, and the RT levels were quantified using TaqMan product-enhanced RT (TM-PERT) assay. Results demonstrated that the amount of RT was positively correlated with the percentage of tetraploid cells circulating in clam haemolymph (R2 = 0.974, p < 0.001). Compared to HN-negative clams (<5% tetraploid cells), 2 stages with significantly elevated levels of RT activity were observed: the first stage at approximately 10 to approximately 20% tetraploid cells, and the second at approximately 30 to approximately 80% tetraploid cells (p < 0.01). These data support the well established fact from mammalian models that transformed cells express high levels of non-telomeric RT. The observed increase in RT levels at approximately 30% tetraploidy coincides with previously reported p53 gene expression. Taken together, this could indicate that using RT levels as an indicator of HN, > or = 30% tetraploidy is the stage at which the disease process undergoes a change, and perhaps becomes irreversible.