Our Dynamic System Imaging approach is centered around developing and refining Light Sheet Microscopy and Light Field Microscopy, in conjunction with other standard imaging modalities, for observation of intact dynamic biological systems. We pursue two goals: advancing the frontiers of microscopy and bringing cutting-edge imaging innovations to the biomedical community through collaborations.
Light Sheet Microscopy (LSM), a century-old imaging technique, has re-emerged in recent years as an ideal modality to provide fast and high-contrast imaging of intact biological samples and processes, with minimal photo-induced damage. In LSM, also known as Selective Plane Illumination Microscopy (SPIM), the sample is excited by a sheet-like illumination pattern and the generated signal is observed along the direction that is orthogonal to the sheet excitation. This unique imaging geometry enables high-contrast optical sectioning as the excitation is restricted to only the detected focal plane; at the same time it provides parallelized excitation and detection to enable fast imaging.
Light Field Microscopy (LFM) is a computational imaging technique where the powers of physical modeling and computation are brought together with conventional physical optics to expand imaging into new performance space. LFM, also first conceptualized more than a century ago, images a 3-dimensional sample from multiple angular views simultaneously, capturing the sample’s 3D information onto a single 2D snapshot, without the need for any physical scanning of the detection focal plane through the sample (as would be done in LSM and other standard imaging modalities). Then, in post-acquisition, a computational algorithm is used to reconstruct the 3D sample from the multiple angular views, enabling very fast volumetric imaging speed (as it is dictated by the 2D imaging speed and not the sequential scanning of the focal plane).
Our group has made several notable contributions to the development and refinement of LSM and LFM over the years. We pioneered the patented technique of using two-photon excitation in LSM, enabling up to twice the imaging penetration depth, while maintaining many of the benefits of standard one-photon excitation LSM [a]. We developed another patented imaging modality that we termed Selective Volume Illumination Microscopy (SVIM), where we combine the selective illumination of LSM with the multiview detection of LFM to achieve the combined benefits of high-contrast and fast volumetric imaging [b].
In parallel with developing new microscopy technologies, we collaborate extensively across disciplines to apply our imaging tools and expertise, creating first-of-its-kind solutions that open new avenues for discovery and experimentation across diverse biological systems. These efforts have led to successful projects spanning dorsal-ventral patterning in fruit fly embryonic development [c], morphogenesis during zebrafish heart development [d], cilia-driven flows involved in bacteria-squid symbiosis [b], left-right symmetry breaking in zebrafish development [e], transcription factors dynamics driving differentiation in plant roots [f], and calcium dynamics in pancreatic islets [g].
[a] Truong TV, Supatto W, Koos DS, Choi JM, Fraser SE. Deep and fast live imaging with two-photon scanned light-sheet microscopy. Nature Methods. (2011) Jul 17;8(9):757-60. doi: 10.1038/nmeth.1652. PubMed PMID: 21765409.
[b] Truong TV, Holland DB, Madaan S, Andreev A, Keomanee-Dizon K, Troll JV, Koo DES, McFall-Ngai MJ, Fraser SE. High-contrast, synchronous volumetric imaging with selective volume illumination microscopy. Communications Biology (2020) Feb 14;3(1):74. doi: 10.1038/s42003-020-0787-6. PubMed PMID: 32060411.
[c] Reeves, G.T., Trisnadi, N., Truong, T.V., Nahmad, M., Katz, S., Stathopoulos, A. Dorsal-ventral gene expression in the Drosophila embryo reflects the dynamics and of the Dorsal nuclear gradient. Developmental Cell, Vol. 22, 544 (2012).
[d] Trivedi, V., Truong, T.V., Holland, D.B., Trinh, L.A., Liebling, M., Fraser, S.E. Dynamic structure and protein expression of the live embryonic heart captured by 2-photon light sheet microscopy retrospective registration. Biomedical Optics Express, Vol. 6(6), 2056-2066 (2015).
[e] Djenoune L, Mahamdeh M., Truong TV, Nguyen CT, Fraser SE, Brueckner M, Howard J, Yuan S. Cilia function as calcium-mediated mechanosensors that instruct left-right asymmetry. Science (2023) 379, 71–78. https://doi.org/10.1126/science.abq7317. PubMed PMID: PMC9939240.
[f] Winter CM, Szekely P, Popov V, Belcher H, Carter R, Jones M, Fraser SE, Truong TV, Benfey, PN. SHR and SCR coordinate root patterning and growth early in the cell cycle. Nature (2024) 626, 611–616. https://doi.org/10.1038/s41586-023-06971-z. PubMed PMID: 38297119.
[g] Bai Y, Jones M, Ojeda LS, Cuala J, Cherchia L, Georgia SK, Fraser SE, Truong TV. Multiscale Light Field Microscopy Platform for Multi-purpose Dynamic Volumetric Bio-imaging. bioRxiv 2024.09.30.615205 (2024) (in revision). https://doi.org/10.1101/2024.09.30.615205.