Date of Award


Document Type

Campus Access Thesis

Degree Name

Master of Science (MS)



First Advisor

Kellee Siegfried

Second Advisor

Linda Huang

Third Advisor

Alexey Veraksa


Germ cells are the only cell type to give rise to the next generation in most animals. Despite this important function, how germ cell development is regulated is unknown. Using mutant analysis in zebrafish, we examined the genetic regulation of germ cell development as it pertains to the testis. Two different zebrafish mutants have been analyzed that have distinct defects in germ cell development: LB023 and moto. The LB023 mutant is a recessive, all male, sterile line that lacks germ cells as adults, whereas the minimoto (moto) mutant has a phenotype whereby germ cells arrest as spermatogonia and do not progress into meiosis. Our data suggests that the LB023 phenotype is caused by a mutation in the solute carrier family 34 (type II sodium/phosphate cotransporter), member 1a protein (slc34a1a). Interestingly, phenotypic analysis of LB023 mutants points to a likely defect in maintenance of the germ line stem cells. Therefore phosphate transport may be necessary for the germ line stem cell niche zebrafish. The moto mutants exhibit a defect in the entry into meiosis. I found that a predicted mutation in a gene, encoding a germ granule component, causes the moto phenotype. Therefore, germgranules may have a necessary role in promoting meiosis. These studies demonstrate previously unknown roles in germ cell development for LB023 and moto. Future analysis of these two mutants will lead to important insights to the biological processes underlying germ cell development and maintenance.


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