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Tilapia as an economically important fish is also an excellent model for studying pigment cell biology and body color formation. In the present study, we engineered a red tilapia by mutation of hps5 using CRISPR/Cas9 gene editing of a target site in exon 2. Disruption of HPS5 led to a significant decrease in the numbers of melanophores and iridophores, and a significant increase in xanthophores, which led to a yellowish-transparent body color in early stages (5–30 dpf, days post fertilization). Slow recovery of iridophore numbers, and increased numbers of xanthophores with shorter nearest-neighbor distances than in wild-type fish was observed at 150 dpf, which finally led to a red tilapia with reddish pigmentation in fins. The hps5−/− mutants also showed several transparent cracks (absence of melanin, iridophores and xanthophores) in iris development. Besides, hps5 was also found to be fundamental for xanthophore development, and even the distance between each of them. Our hps5 mutants provide an excellent new model for studies of HPS5 function. Additionally, the red tilapia mutants may also have potential to serve as new germplasm for aquaculture, or function as a gene resource for genetic modification and breeding of red tilapia and the other related ornamental and food fish in aquaculture. More importantly, this study may have significant values in the area of development and evolution of pigmentation patterns of fish species.
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This content will become publicly available on June 1, 2026
Genome sequencing and identification of candidate variants for a red/black color polymorphism in tilapia (Oreochromis spp.)
Red tilapia are favored by consumers, but the molecular genetic basis for this color pattern is unknown. Here we report on the genetic and physical mapping of the red locus in two strains of tilapia. We raised ~3000 hybrid individuals to map the red locus to a single bacterial artificial chromosome clone on linkage group 3. Long-read sequencing allowed us to assemble contigs spanning both the black and red haplotypes. The red haplotype contains additional repetitive sequence totaling almost one megabase that includes no obvious candidate genes. We suggest that the red phenotype may arise from substitutions in a protein in the primary cilia (Ccdc149), or changes in the expression of a nearby gene (nckx2). Red mutations in several unlinked loci have now been identified, creating an opportunity to identify the best allelic combinations for aquacultural production.
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- Award ID(s):
- 1830753
- PAR ID:
- 10655158
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Aquaculture
- Volume:
- 603
- Issue:
- C
- ISSN:
- 0044-8486
- Page Range / eLocation ID:
- 742411
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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