Kawakami Group / Laboratory of Molecular and Developmental Biology

The dwarf neon rainbowfish Melanotaenia praecox, a smallspiny-rayed fish with potential as a new Acanthomorphamodel fish: II. Establishment of a microinjection procedurefor genetic engineering.

Kazuhide Miyamoto, Gembu Abe, Koichi Kawakami, Koji Tamura, Satoshi Ansai

Developmental Dynamics 2024 Feb 5 DOI:10.1002/dvdy.698

Background: Rainbowfish is a clade of colorful freshwater fish. Melanotaenia praecox is a small rainbowfish species with biological characteristics that make it potentially useful as an experimental model species. We anticipate that M. praecox could become a new model used in various fields, such as ecology, evolution, and developmental biology. However, few previous studies have described experimental set-ups needed to understand the molecular and genetic mechanisms within this species. Results: We describe detailed procedures for genetic engineering in the rainbowfish M. praecox. By using these procedures, we successfully demonstrated CRISPR/Cas-mediated knockout and Tol2 transposon-mediated transgenesis in this species. Regarding the CRISPR/Cas system, we disrupted the tyrosinase gene and then showed that injected embryos lacked pigmentation over much of their body. We also demonstrated that a Tol2 construct, including a GFP gene driven by a ubiquitous promoter, was efficiently integrated into the genome of M. praecox embryos. Conclusions: The establishment of procedures for genetic engineering in M. praecox enables investigation of the genetic mechanisms behind a broad range of biological phenomena in this species. Thus, we suggest that M. praecox can be used as a new model species in various experimental biology fields.

This study was conducted as collaboration with Tamura lab at Tohoku University.

Figure: (A)(B) Male and female Melanotaenia praecox.
(D)(F) Disruption of the tyrosinase gene using CRISPR/Cas9.
(C’)(E’) Introduction of the GFP gene using Tol2.