Honors & Awards

  • Leallyn B. Clapp Prize for Outstanding Senior Honors Thesis in Biochemistry, Department of Chemistry, Brown University (2009)
  • Prize for Academic Excellence in Biology, Division of Biology and Medicine, Brown University (2009)
  • National Science Scholarship (BS-PhD), Agency for Science, Technology and Research, Singapore (2004-present)

Education & Certifications

  • Bachelor of Science, Brown University, Biochemistry (2009)

Stanford Advisors


Journal Articles

  • The ecdysone receptor (ScEcR-A) binds DNA puffs at the start of DNA amplification in Sciara coprophila CHROMOSOME RESEARCH Liew, G. M., Foulk, M. S., Gerbi, S. A. 2013; 21 (4): 345-360


    The steroid hormone ecdysone induces DNA amplification and subsequent DNA puff formation in late fourth larval instar salivary gland polytene chromosomes of the fungus fly, Sciara coprophila. Previous in vitro studies on DNA puff II/9A in Sciara demonstrated that the ecdysone receptor (ScEcR-A) efficiently binds an ecdysone response element adjacent to the origin recognition complex binding site within the II/9A amplification origin, implying a role for ScEcR-A in amplification. Here, we extrapolate the molecular details from locus II/9A to the rest of the genome using immunofluorescence with a ScEcR-A-specific antibody. ScEcR-A binds all DNA puff sites just as amplification begins and persists throughout the processes of amplification, transcription, and puffing. Ecdysone injections into pre-amplification stage larvae prematurely induce both DNA amplification and ScEcR-A binding to DNA puff sites. These data are consistent with a direct role for ScEcR-A in DNA amplification.

    View details for DOI 10.1007/s10577-013-9360-1

    View details for Web of Science ID 000321914600002

    View details for PubMedID 23737076

  • Isolation and characterization of the ecdysone receptor and its heterodimeric partner ultraspiracle through development in Sciara coprophila CHROMOSOMA Foulk, M. S., Waggener, J. M., Johnson, J. M., Yamamoto, Y., Liew, G. M., Urnov, F. D., Young, Y., Lee, G., Smith, H. S., Gerbi, S. A. 2013; 122 (1-2): 103-119


    Regulation of DNA replication is critical, and loss of control can lead to DNA amplification. Naturally occurring, developmentally regulated DNA amplification occurs in the DNA puffs of the late larval salivary gland giant polytene chromosomes in the fungus fly, Sciara coprophila. The steroid hormone ecdysone induces DNA amplification in Sciara, and the amplification origin of DNA puff II/9A contains a putative binding site for the ecdysone receptor (EcR). We report here the isolation, cloning, and characterizing of two ecdysone receptor isoforms in Sciara (ScEcR-A and ScEcR-B) and the heterodimeric partner, ultraspiracle (ScUSP). ScEcR-A is the predominant isoform in larval tissues and ScEcR-B in adult tissues, contrary to the pattern in Drosophila. Moreover, ScEcR-A is produced at amplification but is absent just prior. We discuss these results in relation to the model of ecdysone regulation of DNA amplification.

    View details for DOI 10.1007/s00412-012-0395-4

    View details for Web of Science ID 000316824600009

    View details for PubMedID 23321980

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