Invited Speaker Abstract Submission
Kylie Dunning, PhD
ARC Future Fellow
Robinson Research Institute, School of Biomedicine, The University of Adelaide
Adelaide, South Australia, Australia
Quantifying the molecular and biophysical dynamics of oocytes and embryos offers new insights into the mechanisms governing early development. Advanced optical approaches enable detailed investigation of the metabolic, structural and mechanical properties of mammalian gametes and preimplantation embryos in a label-free, non-invasive manner.
Light sheet microscopy offers orthogonal illumination and detection paths resulting in fast imaging, with very low photo-damage. We have adapted this form of microscopy to operate at a single wavelength to perform hyperspectral imaging of metabolic co-factors NAD(P)H and FAD. Recording this information allowed us to determine the optical redox ratio (a measure of cellular metabolism) and generate the first ever 3D metabolic map of live preimplantation embryos. As a further facet of this approach, we recently completed the first detailed phototoxicity study for light sheet microscopy using immunohistochemistry to sensitively detect DNA damage within the embryo. This confirmed that light sheet imaging is dramatically less phototoxic than confocal microscopy, supporting its use in extended live imaging studies.
To explore biophysical characteristics, we developed a digital holographic microscope to quantify intracellular refractive index in a spatiotemporal manner. This label-free technique captures both phase and amplitude information, revealing subtle differences in lipid-associated refractive index (at the 10⁻³ level) between embryos of differing developmental potential. Imaging was performed at extremely low power densities, avoiding photodamage to the embryo.
Optical tweezers enable precise quantification of viscosity in microliter-scale samples. Using this approach, we quantified the viscosity of the cumulus oocyte matrix by trapping microspheres within matrix isolated from oocytes. The results revealed significant differences between matrices from oocytes with high versus poor developmental potential. This indicates that the mechanical environment surrounding the oocyte may influence key aspects of maturation and developmental potential.
Together, these technologies provide a new window into the dynamic cellular and extracellular landscape of early development. By integrating metabolic, biophysical and mechanical information from oocytes and embryos, these approaches open new avenues for uncovering the fundamental mechanisms that drive reproductive success.