Tag: April DeLaurier

Hdac4 is Required by Early Cranial Neural Crest Cells for the Development of the Zebrafish Palate

Presenter: Vishesh Khanna, Biology

Panel: Genes, Cells & Jaws

Mentor: April DeLaurier, Biology

AM Session Panels

Time: 11:00am – 12:00pm

Location: Century A

Palate deformities are one of the most common congenital birth defects. It is estimated that one in 1000 babies is born with either a cleft lip or a cleft palate. In 2006, single nucleotide polymorphisms in the gene HDAC4 were found to be linked to cleft palate-like defects in humans. In zebrafish, Morpholino-mediated knockdown of hdac4 results in cartilage abnormalities at 6 days post-fertilization, specifically a clefting of the skeletal elements in the roof of the zebrafish mouth. By using fluorescent in situ hybridization, we show that hdac4 knockdown results in the loss of a specific subset of neural crest cells that normally migrate deep to the eye rudiment. Based upon our findings in this animal model, we can propose that human cleft palate resulting from the HDAC4 mutation might ultimately be due to defects in a homologous subset of neural crest cells.

Runx2b Transgene Expressing the Peb2A2 Isoform Shows Spatially Restricted Expression in the Developing Zebrafish Craniofacial Skeleton

Presenter: Nathan Johnson

Mentor: April DeLaurier

PM Poster Presentation

Poster 18

Transgenic techniques have revolutionized the study of cellular, developmental, and molecular biology by allowing researchers to visualize the proteins they study in vivo. When expressed in skeletal elements of the zebrafish (Danio rerio), transgenes allow us to explore cell behavior and the genetic pathways involved in craniofacial morphogenesis. Here we discuss a runx2b transgenic line generated with BAC mediated recombination that expresses 1 of 3 runx2b isoforms, pebp2A2. As an early gene in specifying skeletal cell identity, pebp2A2 expression predicts pre-osteoblasts and pre-chondrocytes. Pebp2A2 expression in progenitor cell populations pre-specifies osteoblasts and chondrocytes prior to expression of other known markers in the skeletogenic pathway, such as sp7, the earliest marker of osteoblast identity. Through the use of spinning disc confocal microscopy, we describe pebp2A2’s spatial and temporal expression in specifying osteoblasts and chondrocytes. Understanding the early specification of osteoblasts will allow us to interpret mutants such as the mef2ca mutant – a mutant with ectopic and mis-patterned craniofacial bones. Subsequent research with the runx2b transgenic line will help us to elucidate the role of the runx2b signaling pathway in ossification and patterning the skeleton.