Meeting Abstract

P2-43   -   The Detection of Extra Retinal Photoreceptors in the Developing Chick (Gallus gallus) Sanusi, J.S*; Perez, J.H; University of South Alabama; University of South Alabama jas1731@jagmail.southalabama.edu

Light exposure during development has emerged as a potential mechanism to accelerate embryonic development, improve hatch synchrony and reduce post-hatch stress responses in galliformes. Despite ample evidence for the positive effects of light on developing avian embryos the mechanisms by which light cues are detected during development remain unclear. Visual photoreceptors in the developing eye are known to become functional around day 14 (E14) of incubation, but effects of light have been reported as early as the first week of incubation. Thus the question arises of how light can be detected early in development. Extra-retinal photoreceptors provide one possible mechanism. Extra-retinal photoreceptors have been identified throughout the brain of adult birds and recent work has found evidence for their expression in chicks. However, the detection of when these proteins first appeared during the process of incubation has not been reported. As a first step to understanding whether these extra-retinal photoreceptors can mediate early light effects we explored when in development these proteins first appear and sought to identify which type of opsins are expressed. White Leghorn (Gallus gallus) eggs were incubated and dissected on embryonic days E3, E5, E10, E15, & E18. Whole brain RNA extraction was performed to aid in quantifying opsin expression across development. Known opsin sequences for neuropsin, VA opsin, melanopsin, and pinopsin were used to analyze expression via RT-qPCR across development.Detection of opsin expression early in development will provide support for the hypothesis that extra-retinal photoreceptors mediate early life light effects.