Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2017

Erindi/veggspjald / Talk/poster E75

Decoding the genetics of the Arctic char morphs in Lake Thingvallavatn

Höfundar / Authors: Benjamín Sigurgeirsson (1), Sébastien Matlosz (1), Arnar Pálsson (1), Sigríður Rut Franzdóttir (1), Sigurður S. Snorrason (1), Zophonías O. Jónsson (1)

Starfsvettvangur / Affiliations: 1 Faculty of Life and Environmental Sciences, University of Iceland

Kynnir / Presenter: Benjamin Sigurgeirsson

Lake Thingvallavatn is a habitat to four morphs of Arctic char: the limnetic; planctivorous (PL) and piscivorous (PI), which have pointed snouts and evenly protruding jaws, and the benthic; large and small benthivorous (LB) and (SB), which have blunt snouts and shorter lower jaws. These morphs are an invaluable system for studies of local phenotypic plasticity, adaptive variation and interactions of plasticity and divergence. We are interested in how genotype and environment, and their interactions, shape these distinct phenotypes, especially during embryonic development and early stages of feeding.
We have used numerous parallel approaches involving mRNA-seq, smallRNA-seq, qPCR and ddRAD-seq to address these questions. All those endeavours would greatly benefit from an available genome sequence thus we undertook whole genome sequencing and partial assembly of the whole genomes of individuals of both sexes from all four Thingvallavatn charr morphs. Although not fully assembled or annotated the genome sequences have revealed genetic divergence of the four morphs and are of great value for our further studies on gene regulation in charr.
While the morphs are clearly genetically separate, an alternative explanation for the observed heritability of morph differences could be epigenetic inheritance mediated by imprinting or differences in maternal deposition of mRNA or miRNAs. The expected result would be differences in CpG methylation patterns between the morphs. Imprinting would provide means for inherently plastic traits to be partially inherited. CpG methylation is itself highly plastic through development, resulting in tissue specific CpG methylation patterns. In order to detect early differences in CpG methylation between the four Thingvallavatn morphs, we will use reduced representation bisulfite sequencing (RRBS), a high-throughput technique for analysing genome-wide methylation profiles with unmatched resolution. This is made possible by the information on the charr genome sequence. We have successfully adapted a RRBS workflow for use with charr embryonic samples and preliminary sequencing results look promising.
This talk will give a brief overview of the Arctic char and the four morphs and of the research our group has conducted so far. The main focus will be on our work on the whole genome sequencing and how we plan to apply that to other work such as the investigation into the epigenome of the Arctic char.