The Melbourne Biophysics Colloquium is a bi-monthly series for Melbourne’s research community in biological physics, microscopy, computational & mathematical biology, and quantitative analysis. These events provide an opportunity for researchers undertaking interesting field-related projects to inform the local community on the progression, challenges, and impact of their current research. The colloquium allows students to hear about the exciting work being undertaken by local leaders in the field and provides opportunities for both researchers and students to meet each other to discuss interests or future academic pursuits.

Date: Bi-monthly with the next colloquium taking place on 29 October 2025
Time: 3:30pm – 5pm
Attend in-person: Laby Theatre, David Caro Building, University of Melbourne, Parkville
Attend online: Click this link to join the meeting. 

Featured speakers – 29 October

• Dr. Jieqiong Lou: BRCA1 vs. 53BP1: Balancing Chromatin Structure and Mobility in DNA Repair

DNA double-strand breaks (DSBs) are among the most lethal forms of DNA damage, repaired primarily by non-homologous end joining (NHEJ) or homologous recombination (HR). While the molecular regulation of these pathways is well characterised, the role of chromatin’s physical state in DSB repair remains poorly understood. Here, using correlative single particle tracking and histone FLIM-FRET microscopy, we uncover a novel biophysical mechanism by which BRCA1 prevents chromatin over-compaction and slows DSB mobility, thereby promoting controlled repair. In contrast, 53BP1 promotes chromatin compaction and increases DSB mobility, acting antagonistically to BRCA1. We further show that dual depletion of BRCA1 and 53BP1 restores chromatin structure and mobility to wild-type levels. These findings explain why BRCA1- deficient cancers are sensitive to poly(ADP-ribose) polymerase (PARP) inhibitors, due to increased DSB mobility, and why loss of 53BP1 in these cancers leads to PARP inhibitor resistance by re-establishing normal chromatin dynamics. Our study reveals a previously unrecognised chromatin-based biophysical mechanism underlying PARP inhibitor response and resistance in BRCA1-deficient patients

• Prof. Ethan Scott: Custom light-sheet microscopy for whole-brain cellular resolution functional imaging in zebrafish

A fundamental challenge to understanding the brain is its complexity: its genetic and developmental programs, its neurons and connections, its balance of permanence and plasticity, and the nuanced information flow through its networks. Across biology, emerging technologies are revolutionising the scope and scale at which we can address such questions. Our group has developed technologies for studying brainwide sensory networks using calcium imaging and house-built light-sheet microscopes. Because zebrafish larvae are small and transparent, we can image tens of thousands of neurons, simultaneously and individually, as animals perceive and respond to sensory stimuli. We have used this approach to produce the first functional maps, brain-wide at cellular resolution, for auditory, vestibular, and water flow perception in any vertebrate.

In this presentation, I will review the design and function of our microscopes, provide examples of the brain-wide networks that they have helped us to study, and discuss ways in which other emerging technologies can help us to explain the anatomical and physiological bases for network function.