Genomic structure of zebrafish dcst2 and the CRISPR gRNA target site used to generate a knockout mutant. Zebrafish dcst2 contains 16 exons and is located on chromosome sixteen. Blue exons denote translated exons and white exons are the Untranslated Regions (UTR). A frame shift mutation in exon 3 was identified in a founder mutant line resulting in premature stop codons. Yellow highlighted nucleotides indicate the PAM sequence and red highlighted nucleotides indicate the guide RNA target sequence. Genotypic ratios generated from crosses between two dcst2+/− mutant zebrafish depicted as a pie chart (B). Transcriptional expression levels of dcst2 relative to actin in the testis confirmed that our mutation likely is being degraded by nonsense-mediated decay (C). Asterisks represent a statistically significant difference (p < 0.05). D, A comparison between muscle and testis dcst2 expression indicating that dcts2 is not expressed in muscle. Asterisks represent a statistically significant difference (p < 0.05). E, Tabulation of male body weight of each fish from each genotype. Asterisks represent a statistically significant difference (p < 0.05). However, this finding was slightly underpowered with the power of the performed test being 0.701 with alpha (α) value set at 0.05

Example heat maps of individual fish swimming behaviour in an open field aquatic arena (A). Swim distance (B). Mean swim velocity of open field swimming behaviour (C). Example image of the swimming tunnel used to assess muscle performance of fish (D). Tabulation of the maximum swim speed (Umax) of our genetic groupings (E). No significant differences were found in any of our measures of motor function

Hematoxylin and eosin staining of male zebrafish trunk cryosections (A). Scale bar represents 500 μm. Insets of cross sections showing no obvious muscle fiber abnormalities (B), scale bar represents 50 µM. Tabulation of slow-twitch muscle fiber cross-sectional area between wild type and dcst2−/− muscle cells (C). Tabulation of fast-twitch muscle fibers cross-sectional area wild type and dcst2−/− zebrafish (D). No significant differences were found in any of our measures of muscle cells