Publications
My articles on Google Scholar.
Published in Optics Letters, 2018
Accurate and rapid particle tracking is essential for addressing many research problems in single molecule and cellular biophysics and colloidal soft condensed matter physics. We developed a novel three-dimensional interferometric fluorescent particle tracking approach that does not require any sample scanning. By periodically shifting the interferometer phase, the information stored in the interference pattern of the emitted light allows localizing particles positions with nanometer resolution. This tracking protocol was demonstrated by measuring a known trajectory of a fluorescent bead with sub-5 nm axial localization error at 5 Hz. The interferometric microscopy was used to track the RecA protein in Bacillus subtilis bacteria to demonstrate its compatibility with biological systems. Read more
Recommended citation: Gdor I, Wang X, Daddysman MK, Yifat Y, Wilton R, Hereld M, Noirot-Gros MF and Scherer NF (2018) "Particle tracking by repetitive phase-shift interferometric super resolution microscopy", Opt Lett, 43:2819-2822. https://doi.org/10.1364/OL.43.002819
Published in Nature Microbiology, 2017
Cell size is specific to each species and impacts cell function. Here, we investigate size control and the cell cycle dependence of bacterial growth using multigenerational cell growth and shape data for single Caulobacter crescentus cells. Our analysis reveals a biphasic mode of growth: a relative timer phase before constriction where cell growth is correlated to its initial size, followed by a pure adder phase during constriction. Cell wall labelling measurements reinforce this biphasic model, in which a crossover from uniform lateral growth to localized septal growth is observed. We present a mathematical model that quantitatively explains this biphasic 'mixer' model for cell size control. Read more
Recommended citation: Banerjee S, Lo K, Daddysman MK, Selewa A, Kuntz T, Dinner AR and Scherer NF (2017) "Biphasic growth dynamics control cell division in Caulobacter crescentus", Nat Microbiol, 2:17116. https://dx.doi.org/10.1038/nmicrobiol.2017.116
Published in Review of Scientific Instruments, 2017
Imaging specific regions of interest (ROIs) of nanomaterials or biological samples with different imaging modalities (e.g., light and electron microscopy) or at subsequent time points (e.g., before and after off-microscope procedures) requires relocating the ROIs. Unfortunately, relocation is typically difficult and very time consuming to achieve. We report the Fast and Accurate Relocation of Microscopic Experimental Regions (FARMER) method, which only requires determining the coordinates of 3 (or more) conspicuous reference points (REFs) and employs an algorithm based on geometric operators to relocate ROIs in subsequent imaging sessions. Read more
Recommended citation: Huynh T, Daddysman MK, Bao Y, Selewa A, Kuznetsov A, Philipson LH and Scherer NF (2017) "Correlative imaging across microscopy platforms using the fast and accurate relocation of microscopic experimental regions (FARMER) method", Rev Sci Instrum, 88(5):053702. https://dx.doi.org/10.1063/1.4982818
Published in Methods in Molecular Biology: Photoswitching Proteins, 2014
The photochemistry of nonnative compounds and the deposition of energy into the cell during imaging can result in unexpected and unwanted side effects. We examine potential live cell damage by first discussing common imaging considerations and modalities in fluorescence microscopy. Read more
Recommended citation: Daddysman MK, Tycon MA and Fecko CJ (2014) "Photoinduced damage resulting from fluorescence imaging of live cells", Methods Mol Bio, 1148, 1-17. https://dx.doi.org/10.1007/978-1-4939-0470-9_1
Published in Journal of Physical Chemistry B, 2014
We investigate the diffusion dynamics of two RNA polymerase II subunits, Rpb3 and Rpb9, in regions of live Drosophila cell nuclei that are devoid of chromatin binding sites. Using FRAP microscopy, we demonstrate that both unengaged subunits are incorporated into a broad distribution of complexes, with sizes ranging from free (unincorporated) proteins to those that have been predicted for fully assembled gene transcription units. Read more
Recommended citation: Tycon MA, Daddysman MK and Fecko CJ (2014) "RNA polymerase II subunits exhibit a broad distribution of macromolecular assembly states in the interchromatin space of cell nuclei", J Phys Chem B, 118:2, 423-433. https://dx.doi.org/10.1021/jp4082933
Published in Journal of Physical Chemistry B, 2013
We apply two-photon excited FRAP with a diffraction limited bleaching and observation volume to study anomalous diffusion of unconjugated green fluorescence protein (GFP) in vitro and in cells. We find that GFP exhibits anomalous diffusion in chromosomal regions but diffuses normally in regions devoid of chromatin. Read more
Recommended citation: Daddysman MK and Fecko CJ (2013) "Revisiting point FRAP to quantitatively characterize anomalous diffusion in live cells", J Phys Chem B, 117:5, 1241-1251. https://dx.doi.org/10.1021/jp310348s
Published in Biophysical Journal, 2011
Multiphoton excitation of DNA in live cells with visible femtosecond pulses produces thymine cyclopyrimidine dimers (CPDs), the primary ultraviolet DNA photoproduct. We demonstrate the utility of this method by applying it to investigate the spatiotemporal recruitment of GFP-tagged topoisomerase I (TopI) to sites of localized DNA damage in polytene chromosomes within live cells of optically thick Drosophila salivary glands. Read more
Recommended citation: Daddysman MK and Fecko CJ (2011) "DNA multiphoton absorption generates localized damage for studying repair dynamics in live cells", Biophys J, 101:9, 2294-2303. https://dx.doi.org/10.1016/j.bpj.2011.09.031
Published in Cancer Cell International, 2010
Kaempferol enhances the effect of cisplatin through down regulation of cMyc in promoting apoptosis of ovarian cancer cells. As a dietary component, kaempferol sensitizes ovarian cancer cells to cisplatin treatment and deserves further studies for possible applications in chemotherapy of ovarian cancers. Read more
Recommended citation: Luo H, Daddysman MK, Rankin GO, Jiang BH and Chen YC (2010) "Kaempferol enhances cisplatin's effect on ovarian cancer cells through promoting apoptosis caused by down regulation of cMyc", Cancer Cell Int, 10:16. https://dx.doi.org/10.1186/1475-2867-10-16
Published in Nutrition and Cancer, 2009
The antiangiogenesis potential of kaempferol and its underlying mechanisms were investigated in two ovarian cancer cell lines, OVCAR-3 and A2780/CP70. Read more
Recommended citation: Luo H, Rankin GO, Liu L, Daddysman MK, Jiang BH and Chen YC (2009) "Kaempferol inhibits angiogenesis and VEGF expression through both HIF dependent and independent pathways in human ovarian cancer cells", Nutr Cancer, 61:4, 554 – 563. https://dx.doi.org/10.1080/01635580802666281
