Semester

Summer

Date of Graduation

2013

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Biochemistry

Committee Chair

Jianbo Yao.

Abstract

SUMOylation is the post-translational modification of proteins by the addition of the small ubiquitin-like modifier (SUMO), which plays an important role in various cellular processes. It has been reported that SUMO and its related proteins are important in diverse reproductive functions such as ovulation, gametogenesis, and embryogenesis. Modification of target proteins by SUMO is an ATP-dependent enzymatic cascade involving three key enzymes: E1 activating enzyme (the heterodimer SAE1-SAE2), E2 conjugating enzyme (UBC9) and several E3 ligating enzymes (PIAS, RanBP2/Nup358 and Pc2). The objectives of this study were to characterize the genes involved in SUMOylation and determine their expression profiles during embryogenesis in rainbow trout. Through database analysis, ten Sumo related genes, which include Sumo1, Sumo2, Sumo3, Sae1, Sae2, Ubc9, Pias1, Pias4, Cbx4, and Nse2, were identified. Analysis of protein sequences of SUMO1 and UBC9, the key components in the pathway, revealed that they are highly conserved among human, mice, rat, cattle, pig, chicken, Xenopus, zebrafish and rainbow trout species. The expression profiles of the Sumo related genes during embryonic development in rainbow trout were analyzed by quantitative real time PCR using cDNAs derived from unfertilized eggs and embryos of 17 different developmental stages (0h, 3h, 7.5h, 11.5h, 13.5h, 18h, 27h, 34h, 2d, 3d, 4d, 5d, 6d, 8d, 10d, 12d, 16d and 25d post fertilization). The expression of Sumo3, Ubc9, Pias4, and Nse2 genes showed similar patterns, being low in unfertilized eggs and increasing gradually in early embryos until 18 h post fertilization followed by a gradual decrease in embryos after 18 h post fertilization; both Sumo1 and Sumo2 genes were highly expressed during maternal to zygotic transition (3d-5d post fertilization); while Sae1, Sae2, Pias1, and Cbx4 were expressed constitutively at steady-state levels throughout embryogenesis. The data indicate that the expression of Sumo related genes are dynamically regulated during the embryonic development in rainbow trout. To better understand how SUMO modification regulates embryonic development, two oocyte specific factors, FIGLA and LHX8, were studied for their interactions with SUMO. Under the experimental conditions used in the study, no apparent interactions of FIGLA or LHX8 with SUMO were detected. The study represents the first attempt to characterize genes involved in SUMOylation in rainbow trout. Further studies to understand the role of SUMOylation in controlling early embryogenesis may ultimately lead to the development of molecular markers for egg quality and embryonic development potential in rainbow trout.

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