Meeting Abstract
The evolution of transcription factor (TF) families and their functions during animal evolution is poorly understood. Comparative assessments for even the best-understood TFs are limited by a lack of information from major animal groups outside the vertebrates and arthropods. To broaden our understanding of TF evolution outside of these animal groups we use the eye of the squid, Doryteuthis pealeii, which has convergently evolved a similar structure to the vertebrate eye, as a comparative model for development of a complex trait. Krüppel-like and specificity protein (KLF/Sp) transcription factors are zinc finger proteins characterized by a DNA binding domain of two cysteines and two histidines (C2H2) repeated in triplicate. In vertebrates and fruit flies, KLF/Sp genes are known to be involved in diverse metabolic, and developmental processes, including in head formation in Drosophila and lens and cornea development in mice. Outside of these groups, Sp6-9 is necessary for optic cup regeneration in planarians, but little else is known about KLF/Sp expression patterns or function. Using RNA sequencing of developing eye and optic lobe tissue we found that several of these genes are expressed in D. pealeii. We identified and phylogenetically placed D. pealeii KLF/Sp family members and characterized the DNA-binding transactivation and repression domains from the predicted amino acid sequences. We then characterized the spatial expression patterns of these genes using in situ hybridization to better understand their potential role in D. pealeii visual system development. We found multiple KLF/Sp genes in D. pealeii expressed specifically in neural, optic lobe, retinal, and anterior segment patterns. These results are the first evidence of the KLF/Sp gene family’s role in eye development in molluscs and may contribute to cephalopod-specific novelties such as the lens.
