Graduation Semester and Year

2009

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Quantitative Biology

Department

Biology

First Advisor

Esther Betran

Abstract

Dntf-2r is a young retroposed gene that originated from the nuclear transport gene Dntf-2. Here the function, quality and evolutionary origin of the regulation of this retrogene are explored. In Chapter 1, I introduce the background of what is known of Dntf-2r as well as the function of its parental gene. This includes their evolutionary histories, and known functional and regulatory aspects. Chapter 2 describes my work on the novel regulatory region recruited by the retrogene and I explore the tissue specific expression pattern (i.e. testis expression) driven by this region. In Chapter 3 I set myself up to review what is known about retrogene regulation. I do this to be able to understand the mechanisms by which young retrogenes can be transcribed to become functional and provide some general understanding of this important feature of retrogenes. In Chapters 4 and 5 I address the function of Dntf-2r. In Chapter 4 I look in detail at the protein compared to the parental protein. I also study its cellular localization and protein interactions using a fusion to EGFP and look at the spermatogenesis and fertility of a Dntf-2r knockout mutant. Finally, as many nuclear transport genes have been implicated or suggested to be involved in causing/suppressing meiotic drive, in Chapter 5, I explore the role of Dntf-2r in meiotic drive using the known Segregation Distortion (SD) system in D. melanogaster.Results reveal a short 14 bp motif in the 5' flanking region is identified as regulatory sequence driving testis specific expression of Dntf-2r. This is a motif is conserved in all species where the gene is present and is similar to the known β2 tubulin promoter motif. Few changes in the region of insertion were required to evolve this element. Our review of how retrogenes are regulated reveals that promoter recruitment and transcription appears to be in many cases highly dependent on the region of insertion. In other instances the initial survival depends on the quality of the transcript: aberrant transcript carrying regulatory regions from parental gene or downstream regulatory regions carried in the normal transcript. In addition, it is evident in some cases of male germline expression, that selective pressures created and or improved the pattern of expression. Functional analysis revealed that Dntf-2r likely retains some interactions of the parental gene; however, it seems to be essentially dispensable for the organism since all fertility assays performed fail to detect significant decrease in fertility. This supports the emerging genetic conflict hypothesis. Additionally, partial knockout of Dntf-2r lowers the affect of otherwise strong SD-5 chromosome suggesting that it may be acting as an enhancer of this meiotic drive system, supporting a meiotic drive involvement.

Disciplines

Biology | Life Sciences

Comments

Degree granted by The University of Texas at Arlington

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