| Summary: | MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression with important roles in the development of animals. The expansive and highly conserved repertoire of vertebrate miRNAs has been proposed as a significant contributor to the clades morphological evolution. Arctic charr is a highly polymorphic species showing great divergence in a wide variety of traits such as adult body size and craniofacial morphology. Here we attempt to further characterize candidate miRNAs in teleost development, involved in processes such as skeletogenesis and developmental timing. We employ qPCR to study the expression of candidate miRNAs in the early development of three Arctic charr morphs and aquaculture charr. Our results suggest a differential expression of miR-199a, miR-17 and miR-19a between dwarf charr compared to other morphs (with lower miR-199a but higher miR-17 and miR-19a expression). We find that Arctic charr has two complete miR-17-92 clusters (containing six miRNAs including miR-17 and miR-19a) and multiple paralogous sequences in our charr genome assemblies. Furthermore, a functional analysis of miR-199a via miR-199a inhibition in zebrafish embryos, results in distinctive changes in craniofacial morphology compared to control groups, mimicking features of the benthic phenotype of Arctic charr. The transcription factor Ets2 was not validated as a target of miR-199a with our current luciferase assay design. Lastly, we show that expression of let-7a in Arctic charr is consistent with the conserved temporal expression of let-7 in bilaterian development. Together, these findings describe the state of selected miRNAs in Arctic charr development and implicate miR-199a in shaping teleost craniofacial morphogenesis. MicroRNA (miRNA) stýra próteintjáningu og gegna mikilvægu hlutverki í þroskun og lífeðlisfræðilegum ferlum dýra sem og annarra heilkjörnunga. Margar vel varðveittar miRNA sameindir í hryggdýrum eru taldar hafa gegnt mikilvægu hlutverki í formfræðilegri (e. morhological) þróun þeirra. Bleikja er ...
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