MS student Tammy Silva will present research project Sep 16th at noon – SE-318
BioSeminars – Wednesday, September 16th, at noon, SE-318
Title: Characterizing the role of tbx22 in zebrafish craniofacial development
Ms. Tammy Silva, Department of Biology UMassD
Dissertation Committee: Dr. Tracie Ferreira (advisor), Dr. Kathy Kavanagh, Dr. Whitney Hable (all at UMassD).
Abstract: Mutations in human TBX22 cause X-linked cleft palate with anklyoglossia syndrome. The two zebrafish tbx22 splice isoforms, tbx22a and tbx22b, encode proteins of 444 and 400 amino acids, respectively. tbx22a resembles canonical Tbx22 orthologs, while tbx22b lacks conserved N-terminal sequence. Zebrafish Tbx22 mRNA expression mirrors mammalian tbx22 expression and is consistent with early patterning of the vertebrate face. In zebrafish, tbx22 mRNA is strongly expressed in ectomesenchymal cells underlying the stomodeum, a bilaminar epithelial structure demarcating the early forming mouth and therefore, is hypothesized to be involved in jaw development. The goal of this work is to characterize the role of tbx22 during craniofacial development in zebrafish. Morpholino technology was used to knockdown tbx22b expression in zebrafish and Alcian Blue staining was used to analyze developing cartilages in tbx22-MO injected zebrafish embryos. Changes in mRNA expression of genes normally expressed near the developing jaw joint and pharyngeal arches was examined in tbx22-MO injected fish using whole mount in-situ hybridization. Our results demonstrate that Tbx22 plays a role in proper patterning of several craniofacial cartilages.
More about Tammy Silva: She attended Stonehill College in Easton, MA, where she majored in Biology and minored in Chemistry. At Stonehill, Tammy conducted research under Dr. Roger Denome and presented a senior honors thesis on the population genetics of the red-backed salamander. Tammy is a member of Dr. Tracie Ferreira’s lab, at UMass Dartmouth, where she studies molecular biology and craniofacial development in zebra fish. Tammy is interested in animal conservation and would like to work at a zoo or an aquarium conducting research that combines molecular biology with animal behavior and conservation.
Filed under: Graduate Student Presentations and
Great seminar. Tammy: can you explain why the knockout embryo will not make it to further stages of development? Also, can you hypothesize what is happening with the yolk? It seemed like the knockout embryos’ yolk looked different from that of the wildtype.
Nice seminar and you were very cool with the technical glitch! Possibly related to Guillermo’s question, I was wondering if there was an overall developmental delay in the embryos, in addition to the amazing cartilage patterning differences.
Hello
Guillermo-we have not actually tried to grow the embryos past 6 days, so I am not positive that they wouldn’t survive. However, at 6 days the knockout embryos not only have mispatterned mouth cartilages but their pectoral fins aren’t as well developed and they often have edema near their hearts. i suspect the embryos wouldn’t survive much longer because they probably could not eat, swim and they are just sickly overall.
Guillermo and Kathy-
There is definitely a developmental delay in the knockout embryos. We have injected missense morpholinos and we don’t see the same phenotypes that we do with the actually tbx22 morpholinos, so we know that it is not simply the injection that is hurting the embryos. We have disrupted tbx22a and tbx22b function as a result of the knockout, so we have probably also disrupted some signaling pathway that is involved in overall growth as well as the craniofacial development and patterning. I think this is why we see the wild type with a smaller yolk. I am looking more into the yolk question, however, if it were just the injection that was causing the yolk issue, you might also expect to see that both tbx22a-MO and tbx22b-MO embryos have the same size yolk and they do not-tbx22b-MO embryos have larger yolks and a more severe phenotype. Perhaps tbx22b has a larger role in development and that’s why we see the more severe phenotype when we knock it out.