A Hypomorphic Cystathionine ß-Synthase Gene Contributes to Cavefish Eye Loss by Disrupting Optic Vasculature

Li Ma, Aniket V. Gore, Daniel Castranova, Janet Shi, Mandy Ng, Kelly A. Tomins, Corine M. van der Weele, Brant M. Weinstein, William R. Jeffery

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Oct 18, 2019
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Received Date: 1st October 19

Vestigial structures are key indicators of evolutionary descent but the mechanisms underlying their development are poorly understood. This study examines vestigial eye formation in the teleost Astyanax mexicanus, which consists of a sighted surface-dwelling morph and different populations of blind cave morphs.  Cavefish embryos initially develop optic primordia but vestigial eyes are formed during larval development.  Multiple genetic factors are involved in cavefish eye loss but none of the mutated genes have been identified.  Here we identify cystathionine ß-synthase (cbsa), which encodes the key enzyme of the transsulfuration pathway, as a mutated gene responsible for eye degeneration in multiple cavefish populations. The inactivation of cbsa affects eye development by inducing accumulation of the transsulfuration intermediate homocysteine and defects in optic vasculature, including aneurysms and eye hemorrhages, leading to oxygen deficiency. Our findings suggest that localized modifications in the circulatory system and hypoxia had important roles in the evolution of vestigial eyes in blind cavefish.

Read in full at bioRxiv.

This is an abstract of a preprint hosted on an independent third party site. It has not been peer reviewed but is currently under consideration at Nature Communications.

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