Masters Theses

Yunsang Lee

Date of Award

8-2000

Degree Type

Thesis

Degree Name

Master of Science

Major

Biochemistry and Cellular and Molecular Biology

Major Professor

Bruce D. McKee

Committee Members

Ranjan Ganguly, Mary Ann Handel

Abstract

Pairing between homologous chromosomes is essential for successful meiosis. In Drosophila melanogaster males, sex chromosome pairing during meiosis I is mediated by rDNA, located in heterochromatin. Several analyses of rDNA fragments showed that 240bp repeats in the intergenic spacer (IGS) have the ability to stimulate X-Y chromosome pairing and disjunction. In addition, point mutations within the promoter of the 240bp repeats failed to mediate X-Y chromosome pairing and disjunction. These previous studies imply that promoter activity of the 240bp repeats is involved in X-Y chromosome pairing in Drosophila males. In this study, I made a construct composed of 16 copies of the 72bp fragment within the 240bp repeat, which has promoter activity and obtained transformant lines with the construct. The construct was transferred to Df(1)X-1, an rDNA deficient X chromosome, by recombination. The effect of the transgene on the frequency of X-Y disjunction were analyzed both by cytological and genetic experiments. The transgene in Df(1)X-1 chromosome induced increased X-Y chromosome disjunction frequency. The result indicates that promoter activity of the 240bp repeats may be responsible for X-Y chromosome pairing in Drosophila males.

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