Abstracts - Society for Developmental Biology

83
understood. Here, we have established the genetic interactions between prdm1a, ap2a/c, and foxd3, key regulators of
neural plate border and neural crest specification in zebrafish embryos. We have shown that prdm1a acts downstream of
Wnt and Notch signaling and forms regulatory feedback loops with foxd3 and tfap2a/c, where perturbation of any of these
members of the gene cascade influences expression of the others as well as normal development of the neural crest.
Through rescue experiments and chromatin-immuno precipitation (ChIP), we have determined that Prdm1a directly binds
to and regulates a putative enhancer for foxd3, an established neural crest specifier, and that foxd3 is a functional direct
target of Prdm1a regulation. Based on these and previous data, we predict that Prdm1a is transcriptional activating foxd3 at
the neural plateborder. Additional data using dominant-activator and dominant-repressor versions of Prdm1a suggest that
Prdm1a functions both as a transcriptional activator and transcriptional repressor during development. By comparing
RNA-seq and ChIP-seq data, we will elucidate the nature of Prdm1a regulation of neural crest specification genes at the
transcriptional level. Through this work, we have demonstrated that prdm1a is an important regulator in the gene network
that is required for proper neural crest formation.
Program/Abstract # 253
A characterization of regulatory linkages in a genetic network for a derived fruit fly trait.
Butts, John C.; McNamee, Connor, University of Dayton, Dayton, United States; Rebeiz, Mark (University of Pittsburgh,
Pittsburgh, United States); Williams, Thomas (University of Dayton, Dayton, United States)
Phenotypes are the culmination of spatial and temporal patterns of gene expression of genes comprising a genetic network.
These patterns are controlled by cis-regulatory elements (CREs) and genes are connected into networks when a CRE
regulating its expression possesses binding sites for network transcription factor proteins - so called regulatory linkages.
Gains and losses of linkages are a suspected common route of CRE and network evolution; though, their emergence
remains poorly understood as few case have revealed the before and after states in sufficient detail. The male-specific
abdominal pigmentation of Drosophila melanogaster evolved from a monomorphic ancestral state, a key modification to
the pigmentation network being the evolution of sexually dimorphic expression of the Bab transcription factor proteins.
These proteins turn off expression of the yellow and tan genes that are required for pigmentation. The research presented
here addresses two questions. First, does Bab form direct regulatory linkages with CREs that control the male-specific
expression of the Drosophila melanogaster yellow and tan genes? Second, when historically were these CREs and the
irregulatory linkages gained? To answer these questions we are: systematically mutating CRE sequences to find motifs
needed to integrate the repressive effects of Bab, and evaluating the regulatory activities of sequences related to the
Drosophila melanogaster CREs. Future studies will explore whether this divergence included the gain of Bab binding sites
in dimorphic species or whether these binding sites were ancestral and conserved during trait evolution.
Program/Abstract # 254
Inspecting the regulatory architecture of a toolkit gene locus governing trait development and evolution
Camino, Eric; Francis, Kaitlyn; Velky, Jordan; Williams, Thomas, University of Dayton, Dayton, United States
Complex spatial and temporal patterns of gene expression are crucial to animal development and changes in expression
patterns are a common mode of evolutionary innovation. Thus, understanding development requires answering: (1) what
are the DNA elements, so called CREs, controlling expression, (2) how the DNA sequences of CREs encode gene
regulatory capabilities, (3) whether and how CREs work together to make complex expression patterns, and (4) how CRE
sequences identify their gene target(s) of regulation in a 3-dimensional nucleus? These answers will aid studies to reveal
the mechanisms of gene expression, and thus animal, evolution. A model to address these questionsis the bab locus of fruit
flies. This locus contains the duplicate bab1 and bab2 genes that shape a derived pattern of pigmentation in the species
Drosophila melanogaster. The relevant bab expression pattern is controlled by two CREs which we found to interact in a
non-additive, or synergistic, way to yield this pattern. Ongoing studies seek to trace: when and how CRE synergism
evolved, which CRE sequences encode their synergistic activity, how these CREs interact with the bab gene promoters,
and whether synergistic regulation extends to additional gene loci. Ultimately, this work aims to connect how animal form
is programmed into 1-dimensional DNA sequence and how this program evolves.
Program/Abstract # 255
Fbxo16 mediated protein degradation regulates neurogenesis in Xenopus laevis
Saritas-Yildirim, Banu; Casey, Elena Silva, Georgetown University, Washington, DC, United States
The development of the central nervous system is a dynamic process during which protein levels are regulated temporally
and spatially by synthesis and degradation. While much is known about the regulation of gene expression during
development, little is known about the control of protein degradation. Studies of cell cycle regulation show that a major
mechanism of protein degradation is through F-box ubiquitin ligases, which function in the recognition and recruitment of