Date Thesis Awarded

4-2017

Document Type

Honors Thesis

Degree Name

Bachelors of Science (BS)

Department

Biology

Advisor

Diane Shakes

Committee Member

Lizabeth Allison

Committee Member

Shanta Hinton

Committee Member

Robert Scholnick

Abstract

Prior to the meiotic divisions, spermatocytes undergo extended developmental processing termed meiotic prophase. As these spermatocytes transition out of meiotic prophase, they must cease transcription and prepare the chromosomes for the meiotic division. Our knowledge of the mechanisms that drive this transition remains incomplete.

In this study, we analyze through cytological and bioinformatics methods a poorly understood Kelch-like protein required for Caenorhabditis elegans spermatogenesis, SPE-26. Analysis of spe-26 mutants reveals precocious meiotic spindle maturation relative to chromatin morphology beginning during the poorly-understood spermatogenesis-specific karyosome stage of late meiotic prophase. spe-26 spermatocytes also display chromosome alignment and segregation defects during the meiotic divisions. Quantitative and qualitative analysis reveal that karyosome entry occurs normally, while similar analysis reveals that spe-26 spermatocytes accumulate within the karyosome stage, suggesting SPE-26 is required for progression through and/or out of the karyosome stage. Using a newly generated antibody, immunofluorescence assays show that SPE-26 concentrates in the nucleus of karyosome stage spermatocytes, is shed to the residual body during the budding division, and is thus absent from spermatids. Next, we use various bioinformatics tools to make predictions of SPE-26 structure and function. We present the predicted secondary and tertiary structures of SPE-26, and compare sequence and structural features to its closest homologs, in addition to other well-studied Kelch-like proteins. Lastly, we predict various functional sites along the structure of SPE-26, including potential phosphorylation sites and a potential nuclear localization signal (NLS).

Available for download on Friday, May 03, 2019

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