Research Group of Dr Liza Pon, Columbia University

Research Group of Dr Liza Pon, Columbia University

Dr Liza Pon is a member of the Department of Anatomy and Cell Biology at Columbia University Medical Center. Liza leads a team of researchers who are working towards a better understanding of cytoskeletal dynamics and function in budding yeast. The group is focused on two specific projects; the role of the actin cytoskeleton in the control of mitochondrial motility and inheritance during cell division, and actin assembly and dynamics during establishment of cell polarity.

Budding yeast are widely used for genetic and genomics studies on fundamental questions in cell and developmental biology. However, since these cells are small (3-6 microns in length) and round, they are challenging for image analysis. Liza took a leading role in visualizing intracellular movement in living yeast cells. Her group has used epifluorescence and spinning disk confocal microscopy for one- and two-color time lapse imaging, digital deconvolution and 3D reconstruction, and 4D imaging (3D reconstruction combined with time lapse imaging) to study organelle movement, organelle-cytoskeletal interactions and cytoskeletal dynamics. Work from Liza’s laboratory revealed that budding yeast is an excellent model system to study organelle inheritance and actin dynamics, and extended our understanding of the mechanisms underlying these fundamental processes.

Liza is a graduate of the University of California, Berkeley, subsequently taking her Ph.D. at Tufts University Health Sciences. This was followed by a post doctoral position at University of Basel, before she returned to the US to join her present department at Columbia University in 1990. She is currently an Associate Professor and Director of the Ph.D. program in her department.

In addition to her research responsibilities, Liza was appointed as Director of the Optical Imaging facility for the Herbert Irving Comprehensive Cancer Center in 1997. This well equipped facility serves researchers throughout the Medical School, providing both imaging equipment and expertise. The facility includes an Openlab microscope system that can be used either as a deconvolution system or to control a spinning disk laser system. Volocity provides the ability to visualize Z stacks in 3D or 4D, measure and track objects and apply iterative restoration to produce confocal quality images. Liza’s group makes full use of the imaging facilities to visualize intracellular movement in yeast as described and has included Openlab and Volocity images in several of their publications.

For more information about their work please visit the Pon Lab page, where you will find details of the current research projects and a number of interesting 3D and 2D time lapse yeast movies.

Colocalization of actin patches and actin cables during retrograde movement. Wild-type haploid cells expressing Abp1p-HcRed and Abp140p-GFP from the chromosomal loci were grown to mid-log phase in lactate medium and were imaged in a single cortical focal plane using simultaneous two-color imaging as for Fig. 1. Images shown are still frames from a time-lapse series showing Abp140p-GFP–labeled actin cables in the top row, Abp1p-HcRed–labeled actin patches in the middle row, and a merged image showing Abp140p-GFP in green and Abp1p-HcRed in red in the bottom row. The cell shown is an unbudded cell in which the presumptive bud site is at the top of the cell. Arrows in the merged images mark an Abp1p-HcRed–labeled actin patch that undergoes linear, retrograde movement along an Abp140p-GFP–labeled actin cable. Bar, 2 µm.

Images acquired using Openlab. Reproduced with permission of the Journal for Cell Biology: Thomas M. Huckaba, Anna Card Gay, Luiz Fernando Pantalena, Hyeong-Cheol Yang, and Liza A. Pon
Live cell imaging of the assembly, disassembly, and actin cable–dependent movement of endosomes and actin patches in the budding yeast, Saccharomyces cerevisiae
J. Cell Biol., Nov 2004; 167: 519 - 530.