The University of Maine Department of Biochemistry, Microbiology, and Molecular Biology Hitchner Hall Room 273 Orono, Maine 04469 Phone: 207-581-2808 Fax: 207-581-2801 Email: jsinger@maine.edu

Research Interests:

Vibriosis, caused in the Northeast and worldwide by the marine bacterium Vibrio anguillarum, is the most pervasive killer of inhabitants of oceanic and estuarine environments, causing mortalities in animals as diverse as bivalves, finfish, and marine mammals.

Under conditions of commercial mariculture cumulative mortalities may reach 40%, and vibriosis has been cited as the major worldwide impediment to the successful commercial rearing of coldwater trout and salmon species. Using an integrated approach of DNA technology, microbial physiology and genetics, and immunological techniques, research in the laboratory is directed at constructing a recombinant Vibrio anguillarum vaccine for the simultaneous protection of salmonids against vibriosis and viral diseases such as infectious pancreatic necrosis.

A significant portion of the forest products industry in Maine is involved in the production of timber for use in building materials and furniture, dictating that the wood be kiln dried. A minimum of 4 x 10¹⁰ lbs of water vapor and organics are removed annually from nearly 30 billion board feet of wood dried in the United States alone. Kiln drying systems can be viewed as either venting evaporated moisture into the environment, or as condensing the evaporated moisture to recover heat energy, allowing the aqueous condensate to drain from the kiln and onto the ground. Biological effects of these uncharacterized wood drying condensates have not been examined. A second research focus in the laboratory is aimed at characterizing the in vitro and in vivo toxicological effects of condensates on life forms from bacteria to eukaryotic cells to mammals.

Selected Publications:

Singer, J. T., and S. Earley. 1989. Identification of polypeptides encoded by cloned pJM1 iron uptake DNA isolated from Vibrio anguillarum 775. J. Bacteriol. 171:2293­2302.

Singer, J. T. 1990. Molecular cloning of the recA analog from the marine fish pathogen Vibrioanguillarum 775. J. Bacteriol. 171:6367­6371.

Singer, J. T., K. A. Schmidt, and P. W. Reno. 1991. Polypeptides p40, pOM2, and pAngR are required for iron uptake and virulence of the marine fish pathogen Vibrio anguillarum 775. J. Bacteriol. 173:1347­1352.

Singer, J. T., W. Choe, and K. A. Schmidt. 1991. Use of a restriction-defective variant for the construction of stable attenuated strains of the marine fish pathogen Vibrio anguillarum. J. Microbiol. Methods 13:49­60.

Singer, J. T., W. Choe, K. A. Schmidt, and R. A. Makula. 1992. Virulence plasmid pJM1 prevents the conjugal entry of plasmid DNA into the marine fish pathogen Vibrioanguillarum775. J. Gen. Microbiol. 138:2485­2490.

Lee, M.­K., S. Blake, J. Singer, and B. Nicholson. 1995. Polymerase chain reaction (PCR) assay for identification of EEV and other Asian strains of aquatic birnaviruses, p. 339­346. In: M. Shariff, J. R. Arthur, and R. P. Subasinghe, (eds.), Diseases in Asian Aquaculture II, Proceedings of the Second Symposium on Diseases in Asian Aquaculture, 25­29 October, 1993, Phuket, Thailand. Fish Health Section, Asian Fisheries Society, Manila, Philippines.

Blake, S. L., W. B. Schill, P. E. McAllister, M.-K, Lee, J. T. Singer, and B. L. Nicholson. 1995. Detection and identification of aquatic birnaviruses by PCR assay. J. Clin. Microbiol. 33:835­839.

Singer, J. T., J. A. Jackson, and R. W. Rice. 1995. Microbiological methods for the detection of mutagens and cytotoxic components in wood drying condensates from Douglas-fir, red oak, southern yellow pine, yellow poplar and eastern white pine. J. Microbiol. Methods 22:229­242.

Mark, H. F. L., R. Naram, J. T. Singer, R. W. Rice, B. Bastan, L. Beauregard, and P. H. LaMarche. 1995. Cytotoxicity and genotoxicity of wood drying condensate from southern yellow pine: an in vitro study. Mutat. Res. 342:191­196.

Singer, J. T., J. A. Jackson, and R. W. Rice. 1995. Investigation of potential toxicity and mutagenicity of distillates from the drying of five species of wood. Forest Products J. 45(5):45­50.

Mark, H. F. L., R. Naram, J. T. Singer, R. W. Rice, B. Bastan, L. J. Beauregard, and P. H. LaMarche. 1996. Wood-drying condensate from eastern white pine induced cytotoxicity and genotoxicity in vitro. Ann. Clin. Lab. Sci. 26:64­70.

Mark, H. F. L., R. Naram, J. T. Singer, R. W. Rice, and P. H. LaMarche. 1996. Douglas-fir: a third wood-drying condensate found to exhibit invitro cytotoxicity and genotoxicity. Ann. Clin. Lab. Sci. 26:269­274.

Mark, H. F. L., R. Naram, J. T. Singer, R. W. Rice, B. Bastan, L. J. Beauregard, and P. H. LaMarche. 1996. Eastern white pine wood-drying condensate induced cytotoxicity and genotoxicity in human peripheral blood lymphocytes in vitro. Cytobios 83:25­31.

Lee, M.-K., S. L. Blake, J. T. Singer, and B. L. Nicholson. 1996. Genomic variation of aquatic birnaviruses analyzed by restriction fragment length polymorphisms (RFLP). Appl. Environ. Microbiol. 62:2513­2520.

Naram, R., J. Cherkes, J. Singer, B. Rice, and H. F. L. Mark. 1996. Evaluation of cytotoxic and genotoxic effects of Douglas-fir condensate on human peripheral blood lymphocytes in vitro. Appl. Cytogenetics 22:65­69. 

Singer, J. T., C. Ma, and K. J. Boettcher. 1996. Overcoming a defect in generalized recombination in the marine fish pathogen Vibrio anguillarum 775: construction of a recA mutant by marker exchange. Appl. Environ. Microbiol. 62:3727­3731.

Singer, J. T., R. W. Rice, L. M. Zibilske, and L. Helyar. 1996. Investigation of acute toxicity of distillates from five species of wood for fathead minnows. Forest Products J. In Press.