04135nas a2200193   4500008004100000022001400041245016700055210006900222260001600291490000700307520344900314100001603763700002203779700003003801700001803831700002203849700002103871856004903892       2023                        eng d  a1471-216400aA new genome assembly of an African weakly electric fish (Campylomormyrus compressirostris, Mormyridae) indicates rapid gene family evolution in Osteoglossomorpha0 anew genome assembly of an African weakly electric fish Campylomo  cMar-20-20230 v243 a<p><jats title="">Abstract</jats><jats sec=""> <jats title="">Background</jats> <jats p="">Teleost fishes comprise more than half of the vertebrate species. Within teleosts, most phylogenies consider the split between Osteoglossomorpha and Euteleosteomorpha/Otomorpha as basal, preceded only by the derivation of the most primitive group of teleosts, the Elopomorpha. While Osteoglossomorpha are generally species poor, the taxon contains the African weakly electric fish (Mormyroidei), which have radiated into numerous species. Within the mormyrids, the genus <jats italic="">Campylomormyrus</jats> is mostly endemic to the Congo Basin. <jats italic="">Campylomormyrus</jats> serves as a model to understand mechanisms of adaptive radiation and ecological speciation, especially with regard to its highly diverse species-specific electric organ discharges (EOD). Currently, there are few well-annotated genomes available for electric fish in general and mormyrids in particular. Our study aims at producing a high-quality genome assembly and to use this to examine genome evolution in relation to other teleosts. This will facilitate further understanding of the evolution of the osteoglossomorpha fish in general and of electric fish in particular.</jats> </jats><jats sec=""> <jats title="">Results</jats> <jats p="">A high-quality weakly electric fish (<jats italic="">C. compressirostris</jats>) genome was produced from a single individual with a genome size of 862&nbsp;Mb, consisting of 1,497 contigs with an N50 of 1,399&nbsp;kb and a GC-content of 43.69%. Gene predictions identified 34,492 protein-coding genes, which is a higher number than in the two other available Osteoglossomorpha genomes of <jats italic="">Paramormyrops kingsleyae</jats> and <jats italic="">Scleropages formosus</jats>. A Computational Analysis of gene Family Evolution (CAFE5) comparing 33 teleost fish genomes suggests an overall faster gene family turnover rate in Osteoglossomorpha than in Otomorpha and Euteleosteomorpha. Moreover, the ratios of expanded/contracted gene family numbers in Osteoglossomorpha are significantly higher than in the other two taxa, except for species that had undergone an additional genome duplication (<jats italic="">Cyprinus carpio</jats> and <jats italic="">Oncorhynchus mykiss</jats>)<jats italic="">.</jats> As potassium channel proteins are hypothesized to play a key role in EOD diversity among species, we put a special focus on them, and manually curated 16 <jats italic="">Kv1</jats> genes. We identified a tandem duplication in the <jats italic="">KCNA7a</jats> gene in the genome of <jats italic="">C. compressirostris</jats>.</jats> </jats><jats sec=""> <jats title="">Conclusions</jats> <jats p="">We present the fourth genome of an electric fish and the third well-annotated genome for Osteoglossomorpha, enabling us to compare gene family evolution among major teleost lineages. Osteoglossomorpha appear to exhibit rapid gene family evolution, with more gene family expansions than contractions. The curated <jats italic="">Kv1</jats> gene family showed seven gene clusters, which is more than in other analyzed fish genomes outside Osteoglossomorpha. The <jats italic="">KCNA7a</jats>, encoding for a potassium channel central for EOD production and modulation, is tandemly duplicated which may related to the diverse EOD observed among <jats italic="">Campylomormyrus</jats> species.</jats> </jats></p>
1 aCheng, Feng1 aDennis, Alice, B.1 aOsuoha, Josephine, Ijeoma1 aCanitz, Julia1 aKirschbaum, Frank1 aTiedemann, Ralph  uhttp://dx.doi.org/10.1186/s12864-023-09196-6