Subterranean Fishes of the World

3253

2017

AIM 2017

The recent human studies indicate an association between autistic symptom and gut microbiome. In general, gut biota is regulated by gut morphology, physiology and ingesting diet. We therefore started investigating the relationship between gut biota, gut morphology and autism spectrum disease (ASD)-like behaviors by using Pachón and Molino cave fish, surface fish and their F1 hybrids. From the one-month-old juvenile stage, the five morphs were fed three diets: nutrientpoor spirulina algae, nutrient-rich brine shrimp and bat guano. Cavefish gut morphology showed significantly less pyloric caeca, longer microvilli, and a wider gut diameter but showed the same gut length comparing with surface fish in the same diet groups. The gut diameters of two cave morphs were widen with the brine shrimp and bat-guano diets comparing with spirulina, whereas surface fish gut morphology stayed as the same, suggesting that the gut plasticity may be evolutionarily acquired in cavefish lineage. Analysis by 16S ribosomal DNA sequencing of the gut biota revealed surface fish and cavefish have significantly different gut biota and F1 hybrids are at intermediate between them. Surprisingly, gut biota is stable in each group regardless of diet, suggesting a major involvement of host genetics. We further looked at short- and medium-chain fatty acids in the intestinal tissue, which are critical nutrients for multiple tissues including nervous system that microbiota supply and the host cannot synthesize by itself. Surface fish gut contains 15.3 times more fatty acids versus cavefish on the same diet, suggesting cavefish may not absorb fatty acid which in turn may lead ASD-like symptom. We are currently further investigating the relationship among the gut plasticity, gut biota, fatty-acid and ASD-like symptom.

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