Project description:To test wheather cavefish have higher lipogenesis capability than surface fish, we used liver sample from fasted and refed fish to do RNA-seq to compare their transcriptome responding to feeding in surface fish and Pachón cavefish. Moreover, we did the Pparγ ChIP-seq with liver from fed surface fish and Pachón cavefish. We amied to test whether Pparγ in Pachón cavefish have more biding sites and higher binding peaks than surface fish.
Project description:We found higher substitution rates in cavefish compared with surface fish, in accordance with a smaller cavefish population size which has allowed more rapid fixation of derived alleles present in the ancestral population. This result also implies that the Pachn cave population is much younger than previously estimated. The comparison of these data with simulations suggests that the Pachn cavefish population has probably been underground less than 30,000 years. This new time frame, together with other evidence, indicate that the evolution of cave phenotypes mainly involves the fixation of cryptic genetic variants present in surface fish populations within a short period of time.
Project description:Reduced parasitic infection rates in the developed world are suspected to underlie the rising prevalence of autoimmune disorders. However, the long-term evolutionary consequences of decreased parasite exposure on an immune system are not well understood. We used the Mexican tetra Astyanax mexicanus to understand how loss of parasite diversity influences the evolutionary trajectory of the vertebrate immune system, by comparing river with cave morphotypes. Here, we present field data affirming a strong reduction in parasite diversity in the cave ecosystem, and show that cavefish immune cells display a more sensitive pro-inflammatory response towards bacterial endotoxins. Surprisingly, other innate cellular immune responses, such as phagocytosis, are drastically decreased in cavefish. Using two independent single-cell approaches, we identified a shift in the overall immune cell composition in cavefish as the underlying cellular mechanism, indicating strong differences in the immune investment strategy. While surface fish invest evenly into the innate and adaptive immune systems, cavefish shifted immune investment to the adaptive immune system, and here, mainly towards specific T-cell populations that promote homeostasis. Additionally, inflammatory responses and immunopathological phenotypes in visceral adipose tissue are drastically reduced in cavefish. Our data indicate that long-term adaptation to low parasite diversity coincides with a more sensitive immune system in cavefish, which is accompanied by a reduction in the immune cells that play a role in mediating the pro-inflammatory response.