Oca2 targeting using CRISPR/Cas9 in the Malawi cichlid Astatotilapia calliptera

Clark, Bethan 
Elkin, Joel 
Marconi, Aleksandra 
Turner, George F. 
Smith, Alan M. 

Change log

Identifying genetic loci underlying trait variation provides insights into the mechanisms of diversification, but demonstrating causality and characterizing the role of genetic loci requires testing candidate gene function, often in non-model species. Here we establish CRISPR/Cas9 editing in Astatotilapia calliptera, a generalist cichlid of the remarkably diverse Lake Malawi radiation. By targeting the gene oca2 required for melanin synthesis in other vertebrate species, we show efficient editing and germline transmission. Gene edits include indels in the coding region, probably a result of non-homologous end joining, and a large deletion in the 3′ untranslated region due to homology-directed repair. We find that oca2 knock-out A. calliptera lack melanin, which may be useful for developmental imaging in embryos and studying colour pattern formation in adults. As A. calliptera resembles the presumed generalist ancestor of the Lake Malawi cichlid radiation, establishing genome editing in this species will facilitate investigating speciation, adaptation and trait diversification in this textbook radiation.

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Online Publication Date
Acceptance Date
Organismal and evolutionary biology, Research articles, cichlids, CRISPR/Cas9, adaptive radiation, functional genetics, evo-devo
Journal Title
Royal Society Open Science
Journal ISSN
Volume Title
The Royal Society
Cancer Research UK (C13474/A18583, C6946/A14492)
Human Frontier Science Program (RGY0079/2018)
NSF (IOS-1825723)
Natural Environment Research Council (NE/R01504X/1)
Wellcome Trust (092096/Z/10/Z, 102175/Z/13/Z, 219475/Z/19/Z, 222279/Z/20/Z)