BIO

Hello, I am Christine Lezama, a sophomore in the pre-med track. I am currently a UROP student working for Dr. Hank Bass' Lab here at FSU. As a part of this lab, I have gained experience in the areas of microscopy and genomics, focusing on the process of DNA replication in eukaryotic cells (maize root tips cells). The project's main goal is to redefine previously known early, middle, and late S phase stages and figure out stage durations and prevalence. From my research, I have gained a strong interest in genetics and cytology and I would love to pursue opportunities in these fields.

Systematizing DNA Replication Patterns Using Dual Label 3D Imaging in Maize

Abstract

Complete and accurate replication of genetic material is required for cells to grow and divide. Accurate genome replication is essential for plants to achieve optimal productivity, serving as the foundation of the food chain and agriculture. To better understand DNA replication in plant cells, we work with collaborators at NCSU to visualize DNA synthesis using 3D microscopy of nuclei from maize root tip cells. The Bass Lab previously observed unique microscopic patterns of DNA Synthesis (S phase) at different time points within the S phase, for instance, early S phase nuclei show DNA synthesis staining patterns that we classify as "distributed" throughout the entire nucleus. In contrast, late S phase nuclei show DNA synthesis staining patterns that we classify as small “patchy” regions. In our study, we employed sequential DNA staining methods, specifically dual labeling techniques with green and red DNA synthesis dyes, to chronologically organize and identify the various patterns (or pattern pairs) in relation to S phase progression. In this way, we gathered image pairs reflecting immediately sequential replication timing patterns and quantified their relative abundance. The pattern categories were Background, Disbursed, Patchy Disbursed, Patchy and Knobby, and finally Knobby, and the pattern pairs quantified were all possible pairs of these. Analysis of over 500 nuclei allowed us to determine how long cells are in each stage of the cell cycle, and to subdivide the patterns beyond the previously known three (early, middle, late) into their proper chronological order.

Keywords: Microscopy, Genetics, Nuclei, DNA replication, Imaging