Conference Paper
Functional and behavioral consequences of the mutation in MAO in the blind cavefish Astyanax mexicanus
Pierre, C., Froc, C., Callebert, J. and Rétaux, S.
Record Number:
3282
Year:
2017
Journal:
AIM 2017
Abstract:
Cavefish (CF) present complex behavioral changes: increased locomotor activity, loss of
aggressive behavior, schooling and sleep. This corresponds to the “cavefish behavioral syndrome”.
We aim at understanding the genetic and neural bases of the behavioral adaptation of A.mexicanus
to the cave environment.
Our group has previously described a point mutation in the Pachón CF gene encoding Monoamine
Oxidase(MAO), the serotonin degrading enzyme. This mutation causes a two-fold reduction of the
MAO activity, and increased brain serotonin level. As accumulated evidences suggest that changes
in neuro-modulatory systems generate significant variations in complex behaviors, we address the
following question: what are the consequences of this MAO mutation at the level of the
serotonergic system and the behavior in CF?
We therefore compared the behaviour and brain serotonin levels of:
1. Normal SF
2. Normal CF
3. CF without the mutation obtained by crosses (the mutation is not fixed in Pachón)
Monoamine levels were measured in the brain of 5 month-old fish by HPLC. The level of serotonin
in the brain of the CF without the mutation was the same as in SF brain. Thus, the difference in
the levels of serotonin between CF and SF is only due to the MAO mutation.
We analyzed fish locomotion. In 5 month-old fish, locomotor activity of CF without the mutation
is lower than in the mutated CF but still higher than in the SF, indicating that the difference in
locomotion between CF and SF is partially due to MAO mutation. However, at 1month of age,
locomotor activity is the same in CF with or without the mutation. This suggests that chronic
inactivation of MAO leads to progressive changes during brain development.
The MAO mutation is found in 4 different independently-evolved cave populations. To generate
a phylogeographic map of MAO mutated alleles, we genotyped 133CF and 178SF from various
caves and rivers. The results suggest that the mutation is probably selected in the cave
environment.
Times Cited:
1
Relevent Species: