| Summary: | Trophic morphology in Teleosts, including the jaw and pharyngeal arches, determines feeding type and performance. Polymorphism in trophic morphology facilitates niche partitioning and the coexistence of morphs within ecosystems. In Lake Thingvallavatn, Iceland, Arctic charr displays four morphs, two benthic; small (SB) and large (LB), and two pelagic; piscivorous (PI) and planktivorous (PL). These ecomorphs show disparity in behaviour, morphology and feeding type, as well as variation in gene expression and heterochronic ontogenetic shifts. The evolutionary and adaptive processes that generate sympatric trophic polymorphism are the subject of much current research. In this project the overall aim was to set up and perform test-runs of experimental systems for evaluating results from gene expression analysis in Arctic charr morphs. These systems are 1) Zebrafish (Danio rerio) as an in vivo model the effects of variation in gene-expression on craniofacial morphogenesis in teleost fish; 2) luciferase assay in primary Arctic charr cell cultures and mammalian cell lines for functional analysis of regulatory interactions. I tested the role of miRNA-199a in generating morphological differences by mimicking (phenocopying) morph phenotypes in zebrafish and set up conditions for primary cell cultures and transfection of a human cell line to validate the predicted miRNA-mRNA target pair miR-199a and ets2. A miR-199a inhibitor was injected into zebrafish embryos and a significant difference in craniofacial morphology was seen, using geometric morphometrics analysis. The results support the notion that the differences in trophic morphology between the Þingvallavatn morphs could, at least in part, be due to an underlying difference in miR-199a expression between the benthic and limnetic morphotypes at developmental stages. Sköpulag fæðuöflunarfæra í fiskum, kjálkar og tálknbogar, hafa áhrif á fæðuöflun og fæðuval. Fjölbrigðni í fæðuöflunarfærum opnar leiðir til nýtingar mismunandi fæðuvista og gerir mismunandi afbrigðum ...
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