Off-campus UMass Amherst users: To download campus access theses, please use the following link to log into our proxy server with your UMass Amherst user name and password.

Non-UMass Amherst users: Please talk to your librarian about requesting this thesis through interlibrary loan.

Theses that have an embargo placed on them will not be available to anyone until the embargo expires.

Document Type

Open Access

Degree Program

Animal Science

Degree Type

Master of Science (M.S.)

Year Degree Awarded

2010

Month Degree Awarded

May

Keywords

DDT, Drosophila, Resistance, Metabolism, P-glycoprotein

Abstract

Resistance to dichlorodiphenyltrichloroethane (DDT) in the 91-R strain of Drosophila melanogaster is extremely high compared to the susceptible Canton-S strain (>1500 times). Oxidative detoxification is involved in resistance but is not the only mechanism. Rates of DDT penetration, metabolism, and excretion were determined radiometrically between resistant 91-R and susceptible Canton-S strains. Contact penetration was ~1.5-times slower with 91-R flies compared to Canton-S flies. The 91-R strain had 13-fold more cuticular hydrocarbons, possibly resulting in penetration differences. DDT was metabolized ~33-fold more extensively by 91-R than Canton-S resulting in dichlorodiphenyldichloroethane (DDD), two unidentified metabolites and polar conjugates being formed in significantly greater amounts. 91-R also excreted ~5.0 times more DDT and metabolites than Canton-S. Verapamil pretreatment reduced the LD50 value for 91-R flies topically dosed with DDT by a factor of 10-fold. Thus, it is likely that the increased excretion by 91-R flies is due to the increased expression of ATP-binding cassette (ABC) transporter genes, including MDR50 (CG8525) that had a 36% higher transcript level by quantitative real time PCR than Canton-S flies. In summary, DDT resistance in 91-R is polyfactorial and includes reduced penetration, increased detoxification and direct excretion.

First Advisor

John M. Clark

Included in

Biotechnology Commons

Share

COinS