Near-complete genome assembly of the African turquoise killifish enables locus-level profiling of transposable element expression

Abstract

Tandem repeats (TRs) and transposable elements (TEs) occupy substantial fractions of eukaryotic genomes, yet how repeat detection programs affect downstream expression analyses remains poorly explored. Here, we present an improved chromosome-scale assembly of the African turquoise killifish, Nothobranchius furzeri. The assembly matches experimentally estimated genome size and chromosome number. It resolves highly expanded TRs that occupy up to 28.0% of the whole genome. Using this assembly and other complete vertebrate genome assemblies, we compared TR and TE-derived regions across combinations of TR detection programs and TE consensus library construction workflows under a standardized TE classification scheme. Choices in TR detection reshaped the apparent TE landscape. TE workflows shared a broad core of TE-derived regions but recovered complementary sets of age- and sex-associated TE loci, evaluated with a sex-balanced killifish multi-tissue aging cohort. Together, the combinatorial use of adaptable programs supports robust, locus-aware detection of complex repeats across genome assemblies.