DE NOVO SYNTHESIS OF NAD+ CONRTIBUTES TO REPRODUCTIVE DEVELOPMENT IN CAENORHABDITIS ELEGANS

Open Access
Author:
Holleran, Lauren Michelle
Area of Honors:
Biochemistry and Molecular Biology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Dr. Wendy Hanna-Rose, Thesis Supervisor
  • Dr. Teh-hui Kao, Honors Advisor
  • Scott Brian Selleck, Faculty Reader
Keywords:
  • NAD+
  • C. elegans
  • de novo pathway
  • reproductive development
  • gonad delay
  • brood size
  • umps-1
Abstract:
NAD+ is a molecule that is crucial in many different biochemical pathways across all organisms as an electron transporter. NAD+ also interacts with other proteins, such as sirtuins, which have been linked to aging and stress. In Caenorhabditis elegans, there are three biosynthetic pathways of NAD+, but my focus will be on a newly discovered pathway present in C. elegans, the de novo pathway. In this study, I will show through manipulation of this pathway that it contributes to reproductive development in C. elegans. In previous studies, it has been shown that blocking the salvage pathway of NAD+ synthesis with pnc-1 mutants results in a gonad delay phenotype. I have found that when knocking out both the de novo and salvage pathways with a umps-1;pnc-1 double mutant, the gonad delay phenotype is more penetrant. In pnc-1 mutants, supplementation with quinolinic acid (QA), a metabolite in the de novo pathway, has been shown to reverse the phenotype by increasing NAD+ levels. I show that supplementing umps-1;pnc-1 worms with QA does not fully reverse the phenotype since umps-1 is required to metabolize QA. In addition to the gonad delay phenotype, I focused on brood size, the number of progeny a single worm has, as an indicator of reproductive development. Also in the de novo pathway, kynu-1 mutants have a lower brood size than wild type. I show that supplementation of kynu-1 mutants with QA rescues the lowered brood size phenotype. I also supplement with nicotinic acid (NA), a metabolite in the salvage pathway. NA most likely increases NAD+, which partially reverses the NAD+-dependent phenotype.