Epha4b gene expression may contribute to variances in facial formation including functional differences such as nose shape and clinical conditions such as cleft palate. During craniofacial development, neural crest cells migrate to the pharyngeal arches then differentiate to form bone, muscle, and cartilage cells. The Eph/ephrin signaling pathway guides the streams of migrating neural crest cells into the pharyngeal arches; epha4b, a gene encoding an Eph receptor, contributes to this signaling pathway. To determine how epha4b expression differs between species at different developmental stages, in situ hybridization, a process that stains areas of gene expression, was performed. African cichlid fish are an ideal model because species have evolved various morphologies based on their feeding. For instance, species such as Labeotropheus fuelleborni evolved a short mandible for biting and species such as Maylandia zebra evolved a long mandible for suction feeding. M. zebra embryos demonstrated low epha4b expression in pharyngeal arch one while L. fuelleborni demonstrated more epha4b expression, suggesting a negative correlation between level of epha4b expression and mandible length. Understanding the factors contributing to craniofacial development and variation will help discover treatments for facial birth defects and conditions.
"Epha4b Expression in the Craniofacial Development of African Cichlid Fishes,"
Journal of the South Carolina Academy of Science: Vol. 16
, Article 10.
Available at: https://scholarcommons.sc.edu/jscas/vol16/iss2/10