More Like this

1. Effect of vortex‐induced physical stress on fluorescent properties of dye‐containing poly(ethylene glycol)‐ block‐poly (lactic acid) micelles

   https://doi.org/10.1002/app.49743  

   Odom, Tyler L.; Blankenship, Jacob R.; Campos, Giselle; Mart, Devin C.; Liu, Wenyan; Wang, Risheng; Yoshimatsu, Keiichi (January 2021, Journal of Applied Polymer Science)

   Abstract The effect of vortex‐induced mechanical stresses on the fluorescent properties of dye‐containing poly(ethylene glycol)‐block‐poly(lactic acid) (PEG‐b‐PLA) block copolymer micelles has been investigated. PEG‐b‐PLA block copolymer micelles containing fluorescent dyes, 3,3′‐dioctadecyloxacarbocyanine perchlorate (DiO) and/or 1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethylindocarbocyanine perchlorate (DiI), are prepared by a simple one‐step procedure that involves the self‐assembly of block copolymers and spontaneous incorporation of hydrophobic dyes into the core of the micelles. Upon vortexing, the micelle dispersion samples showed a decrease in fluorescence intensity in a rotational speed‐ and time‐dependent manner. The results demonstrated that the vortexing can alter the fluorescent properties of the dye‐containing PEG‐b‐PLA block copolymer micelle dispersion samples, suggesting the potential utility of block copolymer micelles as a mechanical stress‐responsive nanomaterial. 

   more » « less
2. Excited state hydrogen or proton transfer pathways in microsolvated n -cyanoindole fluorescent probes

   https://doi.org/10.1039/d3cp04844f  

   Abou-Hatab, Salsabil; Matsika, Spiridoula (January 2024, Physical Chemistry Chemical Physics)

   n-Cyanoindole fluorescent probes hydrogen bonded with one or two water molecules can form cyclic or non-cyclic structures. These structures can lead to excited state proton or hydrogen transfer to the solvent molecules. 

   more » « less
3. Spatial and temporal localization of Serratia ureilytica causing cucurbit yellow vine disease in cucurbits indicates phloem-associated colonization and systemic movement

   https://doi.org/10.64898/2026.02.18.706665  

   Rodriguez-Herrera, Kensy D; Boisvert, Elise; Frank, Margaret H; Smart, Christine D (February 2026, bioRxiv)

   Abstract Cucurbit yellow vine disease (CYVD), caused by the bacteriumSerratia ureilytica, is a phloem-associated disease of cucurbits. This study characterized the spatial and temporal distribution ofS. ureilyticainCucurbita pepocultivar ‘Delicata’ plants under greenhouse conditions using a GFP-tagged isolate (P01). Seedlings were sampled weekly for four weeks. Transverse sections from the stem, petiole, leaf, shoot apex, and root were imaged by laser scanning confocal and fluorescent dissecting microscopy. In parallel, bacterial abundance in each plant tissue was assessed by quantifying colony-forming units (CFU) via droplet plating over a 4-week time course. Across plant tissues and time points,S. ureilyticafluorescent signal was primarily concentrated in the inner and outer periphery of the bicollateral vascular bundles, with higher magnification images revealing mainly symplastic localization within phloem-associated cells. Consistent with the imaging results, bacterial quantification data showed a high abundance of CFUs in the main stem across weeks, with an irregular pattern of presence in the distal tissues at later time points. These results suggest thatS. ureilyticais predominantly localized within phloem-associated cells and spreads both acropetally and basipetally during infection. 

   more » « less
4. Ultrafast spectroscopic signatures for off -to- on photoswitchable species in a green-to-red photoconvertible fluorescent protein

   https://doi.org/10.1039/D5SC06279A  

   Krueger, Taylor D; Chen, Cheng; Fang, Chong (January 2026, Chemical Science)

   Ultrafast electronic and Raman spectroscopies on least evolved ancestor (LEA) fluorescent proteins reveal a distorted photoswitchedoffstate returning toonstate upon photoexcitationviaproton transfer and isomerization, hindering photoconversion. Photoconvertible fluorescent proteins (pcFPs) have greatly advanced life sciences and cellular imaging with sub-diffraction resolution. A subset of Kaede-like pcFPs can reversibly photoswitch and irreversibly photoconvert, which yield intriguing properties for sophisticated bioimaging, yet blinking may complicate image analysis. Many investigations on such pcFPs lack transient information that can dictate their optical properties, especially on ultrafast timescales. We study a family of ancestrally derived pcFPs with varying photoconversion and photoswitching efficiencies based on the least evolved ancestor (LEA). With ultrafast electronic and vibrational spectroscopies that complement steady-state measurements, we dissect the primary events upon near-UV excitation of the native and photoswitched neutral chromophores, which initiates both off → on photoswitching and green-to-red photoconversion. We demonstrate that cis → trans isomerization underlying negative photoswitching occurs the fastest in acidic buffers upon green light irradiation, which forms a distorted neutral off state proportional to the initial green cis anionic population. Femtosecond transient absorption measurements reveal that this dynamic off state rapidly photoswitches back to the bright on state upon near-UV excitation, in contrast to the native form. With various mutants and photoinduced states, we find that off → on photoswitching likely involves excited state proton transfer from the distorted chromophore, which competes with photoconversion. In contrast, femtosecond stimulated Raman spectroscopy (FSRS) of the much less photoswitchable LEA-A69T tracks the efficient nonradiative relaxation of the native cis neutral chromophore. We propose rational design strategies to inhibit off → on photoswitching while improving the photoconversion efficiency of both neutral states. This work is envisioned to inspire more dynamic investigations of diverse photochromic FPs on ultrafast timescales. 

   more » « less
5. Genetic transformation of the frog-killing chytrid fungus Batrachochytrium dendrobatidis

   https://doi.org/10.1073/pnas.2317928121  

   Kalinka, Erik; Brody, Stephanie M; Swafford, Andrew_J M; Medina, Edgar M; Fritz-Laylin, Lillian K (January 2024, Proceedings of the National Academy of Sciences)

   Batrachochytrium dendrobatidis(Bd), a causative agent of chytridiomycosis, is decimating amphibian populations around the world.Bdbelongs to the chytrid lineage, a group of early-diverging fungi that are widely used to study fungal evolution. Like all chytrids,Bddevelops from a motile form into a sessile, growth form, a transition that involves drastic changes in its cytoskeletal architecture. Efforts to studyBdcell biology, development, and pathogenicity have been limited by the lack of genetic tools with which to test hypotheses about underlying molecular mechanisms. Here, we report the development of a transient genetic transformation system forBd. We used electroporation to deliver exogenous DNA intoBdcells and detected transgene expression for up to three generations under both heterologous and native promoters. We also adapted the transformation protocol for selection using an antibiotic resistance marker. Finally, we used this system to express fluorescent protein fusions and, as a proof of concept, expressed a genetically encoded probe for the actin cytoskeleton. Using live-cell imaging, we visualized the distribution and dynamics of polymerized actin at each stage of theBdlife cycle, as well as during key developmental transitions. This transformation system enables direct testing of key hypotheses regarding mechanisms ofBdpathogenesis. This technology also paves the way for answering fundamental questions of chytrid cell, developmental, and evolutionary biology. 

   more » « less