Subterranean Fishes of the World

3900

2016

A recent hypothesis for the evolution of albinism in Astyanax cavefish has postulated the existence of a tradeoff between pigmentation and behavioral changes linked by catecholamine (CAT) levels. However, the previous research did not identify any behavioral differences between surface and cave-dwelling Astyanax that occur during the critical period of larval pigment development. During a recent screen for behavioral or physiological differences linked to pigment development, we noted a difference in anesthesia tolerance. Anesthesia tolerance was tested by exposing fry to ice water or the chemical anesthetic tricaine methanesulfonate (MS-222) and calculating the average time to unconsciousness, based on motion detection. The results showed that albino cavefish larvae treated with anesthesia remained conscious significantly longer than pigmented surface fish larvae. We discovered that the difference in anesthesia tolerance begins between 3 and 4 days post fertilization, during the height of pigmentation in surface fish. Further testing showed that differences in anesthesia tolerance also persisted into adulthood: adult albino cavefish treated with anesthesia remained conscious significantly longer than pigmented adult surface fish. The results suggest a negative correlation between anesthesia tolerance and melanin pigmentation in Astyanax, which is also known to occur in humans. Additional tests on anesthesia tolerance in conjunction with pharmacological treatments will be done in Astyanax to determine whether anesthesia tolerance is based on changes in CAT levels in developing neural systems. Because cave-adapted and surface populations of Astyanax mexicanus are thus far the only natural model system for studying anesthesia tolerance this research could help elucidate the general mechanism of anesthetic action.

1

23rd International Conference on Subterranean Biology

2016

2016

2016