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Genetic and molecular analysis of the garnet eye colour gene of Drosophila melanogaster

University of British Columbia

The garnet eye colour gene of Drosophila melanogaster is one the group of genes called the transport group of eye colour genes. The garnet gene resembles other members of the transport group of eye colour genes in its phenotype and shows extensive genetic interactions with them. The most significant interaction is between garnet and a cryptic allele of the white gene, first identified as a mutation called enhancer of garnet (we(g)). The phenotype of garnet mutations and the extreme sensitivity to decreased levels of the white+ gene product suggest that garnet, as well as other members of the transport group of eye colour genes, act as positive regulators of the white gene. This interaction may occur at the protein level. A simple model for the physical interactions between the gene products of garnet, white and other members of the transport group is proposed. A critical test of this model requires molecular cloning and analysis of the individual members of the transport group of eye colour genes. Preliminary molecular analysis of the garnet gene is reported in chapter two. The garnet gene is expressed in many different tissues at different stages in development. Two messages are produced from the garnet gene in wild type embryos. Conceptual translation of a 4kb c-DNA reveals a novel protein. In the final chapter I describe the use of the garnet gene to study an example of epigenetic gene regulation. I have examined a mini-chromosome which variegates for the garnet gene. The variegation of this mini-chromosome is extremely unusual in that it depends on the sex of the fly transmitting the mini chromosome. In this way it conforms to the conventional definition of parental genomic imprinting. I examined a number of possible mechanisms which might be responsible for the parental imprinting of the mini-chromosome The results suggest that heterochromatin formation is responsible for the somatic expression of the genomic imprint, but a different system may operate to establish the imprint.

Thesis/Dissertation

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2009-04-22

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http://hdl.handle.net/2429/7491

Genetics

University of British Columbia

UBCV

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