Effect of First, Second and Third Chromosome on the Promoter Activity of Cyp6a8 Gene of Drosophila Melanogaster

Author

Anirban Mukherjee, University of Tennessee - Knoxville

Date of Award

12-2008

Degree Type

Thesis

Degree Name

Master of Science

Major

Life Sciences

Major Professor

Ranjan Ganguly

Committee Members

Mariano Labrador, Jae H. Park

Abstract

The mechanism of insect CYP gene regulation is largely unknown. In the present investigation, I used Drosophila as a model insect to understand the role of X, 2^nd and 3^rd chromosomes on the promoter activity of Cyp6a8 gene. Two reporter transgenic strains, 0.8luc110 H-ry and 0.8luc14, carrying 0.8luc-A8 reporter transgene (chimera of 0.8-kb upstream DNA of Cyp6a8 and the firefly luciferase gene) on the 2^nd and 3^rd chromosomes of ry⁵⁰⁶, respectively were used. The X, 2^nd and 3^rd chromosomes of these two transgenic lines were replaced with corresponding chromosomes from DDT-resistant 91-R strain (overproducer of Cyp6a8). The effect was determined by measuring luciferase activity. Results showed that the 3^rd chromosome of the 91-R strain had a strong and the 2^nd chromosome had a weak stimulatory effect on Cyp6a8 expression. The effect of the 1^st chromosome was strongly inhibitory only if the 3^rd chromosome from 91-R and the 2^nd chromosome from the ry⁵⁰⁶ strains were present in the genome. Chromosomal effect on the Inducibility of 0.8-kb Cyp6a8 promoter DNA by phenobarbital and barbital was also examined. It was found that these compounds could induce the promoter significantly if the genome had X or second chromosome from the ry⁵⁰⁶ or 91-R strain. However, no induction was observed when the third chromosome of 91-R was present in the genome but the third chromosome of the ry⁵⁰⁶ strain supported barbiturate inducibility of the Cyp6a8 promoter.

To further investigate if Cyp6a8 is regulated by other genes, I studied the effect of third chromosome-linked DHR96 (mammalian CAR/RXR homolog) mutation on the promoter activity of the 0.8Kb upstream DNA of Cy6a8. I found that the DHR96 mutation gave 7-12 fold higher constitutive expression of Cyp6a8 compared to the wild type strain in all developmental stages. This investigation concludes that Cyp6a8 expression in Drosophila is influenced by all three major chromosomes and the third chromosome-linked DHR96 gene has a negative effect on Cyp6a8 expression.

Recommended Citation

Mukherjee, Anirban, "Effect of First, Second and Third Chromosome on the Promoter Activity of Cyp6a8 Gene of Drosophila Melanogaster. " Master's Thesis, University of Tennessee, 2008.
https://trace.tennessee.edu/utk_gradthes/472