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Transcriptional dynamics of a conserved gene expression network associated with craniofacial divergence in Arctic charr

Transcriptional dynamics of a conserved gene expression network associated with craniofacial divergence in Arctic charr


Title: Transcriptional dynamics of a conserved gene expression network associated with craniofacial divergence in Arctic charr
Author: Pashay Ahi, Ehsan   orcid.org/0000-0002-6528-1187
Kapralova, Kalina H.
Palsson, Arnar   orcid.org/0000-0002-6525-8112
Maier, Valerie
Guðbrandsson, Jóhannes   orcid.org/0000-0002-2231-0910
Snorrason, Sigurdur S
Jónsson, Zophonías Oddur   orcid.org/0000-0001-5798-9647
Franzdottir, Sigridur Rut   orcid.org/0000-0001-9300-7022
Date: 2014
Language: English
Scope: 40
University/Institute: Háskóli Íslands
University of Iceland
School: Verkfræði- og náttúruvísindasvið (HÍ)
School of Engineering and Natural Sciences (UI)
Department: Líf- og umhverfisvísindadeild (HÍ)
Faculty of Life and Environmental Sciences (UI)
Lífvísindasetur (HÍ)
Biomedical Center (UI)
Series: EvoDevo;5(1)
ISSN: 2041-9139
DOI: 10.1186/2041-9139-5-40
Subject: Arctic charr; Coexpression; Craniofacial development; Divergent evolution; Gene network; Morphogenesis; Salvelinus alpinus; Bleikja; Þróun lífsins; Erfðafræði
URI: https://hdl.handle.net/20.500.11815/368

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Citation:

Ahi, E. P., Kapralova, K. H., Pálsson, A., Maier, V. H., Gudbrandsson, J., Snorrason, S. S., . . . Franzdóttir, S. R. (2014). Transcriptional dynamics of a conserved gene expression network associated with craniofacial divergence in Arctic charr. EvoDevo, 5(1), 40. doi:10.1186/2041-9139-5-40

Abstract:

Background Understanding the molecular basis of craniofacial variation can provide insights into key developmental mechanisms of adaptive changes and their role in trophic divergence and speciation. Arctic charr (Salvelinus alpinus) is a polymorphic fish species, and, in Lake Thingvallavatn in Iceland, four sympatric morphs have evolved distinct craniofacial structures. We conducted a gene expression study on candidates from a conserved gene coexpression network, focusing on the development of craniofacial elements in embryos of two contrasting Arctic charr morphotypes (benthic and limnetic). Results Four Arctic charr morphs were studied: one limnetic and two benthic morphs from Lake Thingvallavatn and a limnetic reference aquaculture morph. The presence of morphological differences at developmental stages before the onset of feeding was verified by morphometric analysis. Following up on our previous findings that Mmp2 and Sparc were differentially expressed between morphotypes, we identified a network of genes with conserved coexpression across diverse vertebrate species. A comparative expression study of candidates from this network in developing heads of the four Arctic charr morphs verified the coexpression relationship of these genes and revealed distinct transcriptional dynamics strongly correlated with contrasting craniofacial morphologies (benthic versus limnetic). A literature review and Gene Ontology analysis indicated that a significant proportion of the network genes play a role in extracellular matrix organization and skeletogenesis, and motif enrichment analysis of conserved noncoding regions of network candidates predicted a handful of transcription factors, including Ap1 and Ets2, as potential regulators of the gene network. The expression of Ets2 itself was also found to associate with network gene expression. Genes linked to glucocorticoid signalling were also studied, as both Mmp2 and Sparc are responsive to this pathway. Among those, several transcriptional targets and upstream regulators showed differential expression between the contrasting morphotypes. Interestingly, although selected network genes showed overlapping expression patterns in situ and no morph differences, Timp2 expression patterns differed between morphs. Conclusion Our comparative study of transcriptional dynamics in divergent craniofacial morphologies of Arctic charr revealed a conserved network of coexpressed genes sharing functional roles in structural morphogenesis. We also implicate transcriptional regulators of the network as targets for future functional studies.

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This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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