Semester

Spring

Date of Graduation

2020

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Division of Plant and Soil Sciences

Committee Chair

Teiya Kijimoto

Committee Member

Daniel Panaccione

Committee Member

Yong-Lak Park

Abstract

Developmental plasticity is the phenotypic variation between organisms that is caused by environmental interactions affecting the developmental systems of organisms. The research focused primarily on nutrition-responsive developmental plasticity. In this research we used the nutritionally determined head horn development of Onthophagus taurus to better understand the developmental mechanisms and genetic underpinnings of nutrition-responsive trait development. We focused specifically on altering the availability of specific nutrition-related primary metabolites, cholesterol and palmitic acid, identified in the activity of The Hedgehog pathway, a critical pathway in head horn development. By altering diet composition using cholesterol, reducing transcript expression of an acyltransferase gene, rasp, which is involved in Hedgehog pathway activity, and by reducing transcript expression of lipophorin receptors responsible in part for lipid and cholesterol resource allocation, this study used diverse approaches to determine the developmental significance of specific nutrients. As well, a pharmaceutical drug, atorvastatin, was used as an isoprenoid biosynthesis inhibitor, a signaling pathway which was identified to have possible impacts on known effectors of horn size. The results of this study indicated that nutrient modification and resource allocation play a role in regulating O. taurus body and horn development to maintain the distribution pattern of discrete morphs. Further, the results showed that statin supplementation may cause a shift in the evolved body/horn size relationship in an O. taurus population. Overall, we saw that resource mobilization and environmental changes impacted the developmental mechanisms regulating horn growth, which indicated that individual nutrients are involved in the developmental plasticity of specific traits.

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