Biology subjects

Tagawa, Y.

Publications and source records attributed to Tagawa, Y..

4 recordsLinked to original sources

bioRxiv2024

Isotonic and minimally invasive optical clearing media for live cell imaging ex vivo and in vivo

Tissue clearing has been widely used for fluorescence imaging of fixed tissues, but not for live tissues due to its toxicity. Here we develop minimally invasive optical clearing media for fluorescence imaging of live mammalian tissues. Light scattering is minimized by adding spherical polymers with low osmolarity to the extracellular medium. A clearing medium containing bovine serum albumin (SeeDB-Live) is minimally invasive to live cells, allowing for structural and functional imaging of live tissues, such as spheroids, organoids, acute brain slices, and the mouse brain in vivo. SeeDB-Live minimally affects the electrophysiological properties and sensory responses of neurons. We demonstrate its utility for widefield imaging of subcellular voltage dynamics, such as backpropagating action potentials, in acute brain slices. We also utilize SeeDB-Live for widefield voltage imaging of dozens of dendrites in vivo, demonstrating population dynamics. Thus, SeeDB-Live expands the scale and modalities of fluorescence imaging of live mammalian tissues.

neuroscience↗

bioRxiv2021

Developmental stage-specific patterned activity contributes to callosal axon projections

The developing neocortex exhibits spontaneous network activity with various synchrony levels, which has been implicated in the formation of cortical circuits. We previously reported that the development of callosal axon projections, one of the major long-range axonal projections in the brain, is activity dependent. However, what sort of and when activity is indispensable are not known. Here, using a genetic method to manipulate network activity in a stage-specific manner, we demonstrated that network activity contributes to callosal axon projections in the mouse visual cortex during a "critical period": restoring neuronal activity during that period resumed the projections, whereas restoration after the period failed. Furthermore, in vivo Ca2+ imaging revealed that the projections could be established even without fully restoring highly synchronous activity. Overall, our findings suggest that the spontaneous network activity is selectively required during a critical developmental time window for the formation of long-range axonal projections in the cortex. (150)

neuroscience↗

bioRxiv2019

Long-range interhemispheric projection neurons show biased response properties and fine-scale local subnetworks in mouse visual cortex

Integration of information processed separately in distributed brain regions is essential for brain functions. This integration is enabled by long-range projection neurons, and further, concerted interactions between long-range projections and local microcircuits are crucial. It is not well known, however, how this interaction is implemented in cortical circuits. Here, to decipher this logic, using callosal projection neurons (CPNs) as a model of long-range projections, we found that CPNs exhibited distinct response properties and fine-scale local connectivity patterns. In vivo 2-photon calcium imaging revealed that CPNs showed a higher ipsilateral eye (with respect to their somata) preference, and that CPN pairs showed stronger signal/noise correlation than random pairs. Slice recordings showed CPNs were preferentially connected to CPNs, demonstrating the existence of projection target-dependent fine-scale subnetworks. Collectively, our results suggest that long-range projection target predicts response properties and local connectivity of cortical projection neurons.

neuroscience↗

bioRxiv2018

Histophilus somni Survives in Bovine Macrophages by Interfering with Phagosome-Lysosome Fusion, but Requires IbpA for Optimal Serum Resistance

Histophilus somni survives intracellularly in professional phagocytic cells, but the mechanism of intracellular survival is not understood. The Fic motif within the DR1/DR2 IbpA fibrillar network protein of H. somni is cytotoxic to epithelial and phagocytic cells, which may interfere with the bactericidal activity of these cells. To determine the contribution of IbpA and Fic on resistance to host defenses, strains and mutants that lack all of or a small region of ibpA or DR1/DR2 were tested for survival in bovine monocytic cells and for serum susceptibility. A mutant lacking IbpA, but not DR1/DR2, was more susceptible to killing by antiserum than the parent. H. somni strains expressing IbpA replicated in bovine monocytes for at least 72 hours, and were toxic for these cells. Virulent strain 2336 with transposon insertions or deletions within IbpA remained toxic for bovine monocytes. However, strain 2336 mutants lacking all of ibpA or both DR1/DR2 were not toxic to the monocytes, but survived within the monocytes for at least 72 hours. Examination of intracellular trafficking of H. somni with monoclonal antibodies to early and late phagosomal markers indicated that early phagosomal marker EEA-1 colocalized with both disease isolate strain 2336 and serum-sensitve mucosal isolate strain 129Pt, but only strain 2336 did not co-localize with late lysosomal marker LAMP-2 and prevented acidification of phagosomes. These results indicate that virulent isolates of H. somni are capable of surviving within phagocytic cells through interference of phagosome-lysosome maturation. Therefore, H. somni may be considered a permissive intracellular pathogen.

microbiology↗