Professional Education


  • Bachelor of Arts, Rice University, Biochemistry and Cell Biology (2013)
  • Doctor of Philosophy, University of California Berkeley (2019)
  • BA, Rice University, Biochemistry and Cell Biology (2013)
  • Ph.D., University of California, Berkeley, Molecular and Cell Biology (2019)

Stanford Advisors


All Publications


  • Ribosomal protein RPL26 is the principal target of UFMylation PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Walczak, C. P., Leto, D. E., Zhang, L., Riepe, C., Muller, R. Y., DaRosa, P. A., Ingolia, N. T., Elias, J. E., Kopito, R. R. 2019; 116 (4): 1299–1308
  • Ribosomal protein RPL26 is the principal target of UFMylation. Proceedings of the National Academy of Sciences of the United States of America Walczak, C. P., Leto, D. E., Zhang, L., Riepe, C., Muller, R. Y., DaRosa, P. A., Ingolia, N. T., Elias, J. E., Kopito, R. R. 2019

    Abstract

    Ubiquitin fold modifier 1 (UFM1) is a small, metazoan-specific, ubiquitin-like protein modifier that is essential for embryonic development. Although loss-of-function mutations in UFM1 conjugation are linked to endoplasmic reticulum (ER) stress, neither the biological function nor the relevant cellular targets of this protein modifier are known. Here, we show that a largely uncharacterized ribosomal protein, RPL26, is the principal target of UFM1 conjugation. RPL26 UFMylation and de-UFMylation is catalyzed by enzyme complexes tethered to the cytoplasmic surface of the ER and UFMylated RPL26 is highly enriched on ER membrane-bound ribosomes and polysomes. Biochemical analysis and structural modeling establish that UFMylated RPL26 and the UFMylation machinery are in close proximity to the SEC61 translocon, suggesting that this modification plays a direct role in cotranslational protein translocation into the ER. These data suggest that UFMylation is a ribosomal modification specialized to facilitate metazoan-specific protein biogenesis at the ER.

    View details for PubMedID 30626644

  • Multi-endpoint, High-Throughput Study of Nanomaterial Toxicity in Caenorhabditis elegans ENVIRONMENTAL SCIENCE & TECHNOLOGY Jung, S., Qu, X., Aleman-Meza, B., Wang, T., Riepe, C., Liu, Z., Li, Q., Zhong, W. 2015; 49 (4): 2477–85

    Abstract

    The booming nanotechnology industry has raised public concerns about the environmental health and safety impact of engineered nanomaterials (ENMs). High-throughput assays are needed to obtain toxicity data for the rapidly increasing number of ENMs. Here we present a suite of high-throughput methods to study nanotoxicity in intact animals using Caenorhabditis elegans as a model. At the population level, our system measures food consumption of thousands of animals to evaluate population fitness. At the organism level, our automated system analyzes hundreds of individual animals for body length, locomotion speed, and lifespan. To demonstrate the utility of our system, we applied this technology to test the toxicity of 20 nanomaterials at four concentrations. Only fullerene nanoparticles (nC60), fullerol, TiO2, and CeO2 showed little or no toxicity. Various degrees of toxicity were detected from different forms of carbon nanotubes, graphene, carbon black, Ag, and fumed SiO2 nanoparticles. Aminofullerene and ultraviolet-irradiated nC60 also showed small but significant toxicity. We further investigated the effects of nanomaterial size, shape, surface chemistry, and exposure conditions on toxicity. Our data are publicly available at the open-access nanotoxicity database www.QuantWorm.org/nano.

    View details for DOI 10.1021/es5056462

    View details for Web of Science ID 000349806400061

    View details for PubMedID 25611253

    View details for PubMedCentralID PMC4336152

  • QuantWorm: A Comprehensive Software Package for Caenorhabditis elegans Phenotypic Assays PLOS ONE Jung, S., Aleman-Meza, B., Riepe, C., Zhong, W. 2014; 9 (1): e84830

    Abstract

    Phenotypic assays are crucial in genetics; however, traditional methods that rely on human observation are unsuitable for quantitative, large-scale experiments. Furthermore, there is an increasing need for comprehensive analyses of multiple phenotypes to provide multidimensional information. Here we developed an automated, high-throughput computer imaging system for quantifying multiple Caenorhabditis elegans phenotypes. Our imaging system is composed of a microscope equipped with a digital camera and a motorized stage connected to a computer running the QuantWorm software package. Currently, the software package contains one data acquisition module and four image analysis programs: WormLifespan, WormLocomotion, WormLength, and WormEgg. The data acquisition module collects images and videos. The WormLifespan software counts the number of moving worms by using two time-lapse images; the WormLocomotion software computes the velocity of moving worms; the WormLength software measures worm body size; and the WormEgg software counts the number of eggs. To evaluate the performance of our software, we compared the results of our software with manual measurements. We then demonstrated the application of the QuantWorm software in a drug assay and a genetic assay. Overall, the QuantWorm software provided accurate measurements at a high speed. Software source code, executable programs, and sample images are available at www.quantworm.org. Our software package has several advantages over current imaging systems for C. elegans. It is an all-in-one package for quantifying multiple phenotypes. The QuantWorm software is written in Java and its source code is freely available, so it does not require use of commercial software or libraries. It can be run on multiple platforms and easily customized to cope with new methods and requirements.

    View details for DOI 10.1371/journal.pone.0084830

    View details for Web of Science ID 000329862500176

    View details for PubMedID 24416295

    View details for PubMedCentralID PMC3885606