Characterizing the Phenotype of the Novel Zebrafish Mutant 152N

Objectives: Human craniofacial defects occur one in 700 live births. Identifying the genetic basis and development pathways responsible for these defects may offer better pre-natal treatments to prevent them, and therapies for effective repair. One way to accomplish this goal is to use mutant zebrafish as functional models for human craniofacial and mineralized tissue defects and disease. In this study, we characterized a recently identified mineralized tissue mutant zebrafish family, 152N.

Methods: A forward genetic mutagenesis screen was performed in zebrafish (Andreeva et al., 2011).  The 152N family was selected for further analyses, due to its evident short fin phenotype as compared to wild type siblings.  A developmental series of 152N mutant fish, aged 1 to 6 weeks, was stained with Alizarin Red (AR) to examine mineralized tissue formation, examined using a Leica MZ12 microscope, imaged using a Olympus DP71 digital camera, and analyzed using Adobe Photoshop and PowerPoint. 

Results: The 152N zebrafish as young as 3 weeks exhibited mutant phenotypes, consisting of short tail fins with fewer segments per fin ray, and craniofacial abnormalities.  Centrally positioned tail fin rays were longest in 152N mutants, while laterally positioned tail fin rays were longest in wild type siblings.  Mutants also exhibited an extended mandible, abnormally shaped maxilla, and ectopic sutures.

Conclusions: Ongoing studies are being conducted to further classify the 152N mutant, including paraffin sectioning and immunohistochemical analyses of bone marker expression.