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Access Type

WSU Access

Date of Award

January 2022

Degree Type


Degree Name



Biological Sciences

First Advisor

Markus Friedrich


Paired box 6 (Pax6) is a highly conserved transcription factor that plays important roles in the development of the eye, central nervous system, and the pancreas. As a master regulator gene, Pax6 plays controls the specification of eyes by regulating a network of retinal determination genes. Studies of Pax6 have provided vital insights into eye evolution. In vertebrates, Pax6 participates in the development of both neuron and non-neuronal cells. However, no evidence has been reported that the Pax6 genes eyeless (ey) and twin of eyeless (toy) are required for the development of non-neuronal cell fates of the Drosophila compound eye. In this study, I present functional evidence that ey is involved in the differentiation of the corneal lens and pigment cells during the development of the compound eye in the red flour beetle Tribolium castaneum. Guided by transcriptome data, I provide evidence that the cuticle genes CP7, CP63, and LOC662799 are required for the normal development of the corneal lens, serving as candidate downstream genes of ey. I further show that Tyrosine Hydroxylases (TH), a key melanogenesis gene, is an essential for normal compound eye development in Tribolium. While melanogenesis was not considered to contribute to the pigmentation process for the compound eye in arthropods, I provide genetic evidence that melanin is an ancient component of the arthropod compound eye pigment layer. By staged knockdown experiments in Tribolium, I further demonstrate that ey is crucial for the normal development and melanogenesis of the Tribolium compound eye. Further experiments indicate that ey is expressed in the developingsecondary pigment cells, where ey regulates the normal formation of the corneal lens and the peripheral eye margin via the SNAIL2 homolog escargot.

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