Subterranean Fishes of the World

4872

2009

The FASEB Journal

415.6

23(S1)

The Mexican tetra, Astyanax mexicanus, is a fish that exists as two morphs of the same species; one sighted and one blind. Several regressive and constructive changes have been identified within blind tetra compared to their sighted ancestors. Of particular note here are the taste buds. Using immunohistochemical markers for receptor cells, basal cells and innervating axons (calretinin, serotonin, and zn‐12/tubulin), we have documented the distribution, number and development of taste buds on the upper and lower lips of the blind versus sighted Mexican tetra. We detected a difference in taste bud morphology between the two morphs as well as substantially more taste buds in blind versus sighted tetras. We show that as early as 5dpf blind tetra larvae have more taste buds on their lips than sighted tetras. The significance of this constructive evolutionary change in concert with the regressive change of losing eyesight will be discussed. This study is the first to document the timing of development of constructive changes which accompany the loss of eyes in the Mexican tetra and lays the foundation for future studies on gene expression patterns which mediate these changes.

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