Biology subjects

Talbot, W. S.

Publications and source records attributed to Talbot, W. S..

7 recordsLinked to original sources

bioRxiv2026

Rapid Electro-optic Two-photon Bessel Light Sheet Fluorescence Lifetime Imaging for Tissue Volume Interrogation

We report a two-photon light sheet electro-optic fluorescence lifetime imaging microscopy (TPLS-EO-FLIM) technique based on an electro-optic (EO) modulation detection module. Scanning two-photon Bessel light sheet excitation was used to achieve in-depth volumetric imaging. The low cross-section of multiphoton excitation requires high detection efficiency, and electro-optic detection enables fast wide-field FLIM with a scientific complementary metal-oxide-semiconductor (sCMOS) detector. Phototoxicity is minimized by utilizing signal from the entire illuminated sample area in a wide field camera exposure, and time-resolved volume acquisitions are feasible in minutes, with cross-sectional field of view and light sheet length over 300 microns. The method has sub-nanosecond lifetime resolution and is capable of accurate FLIM images in 10 ms exposures with as low as a few hundred photons per pixel. The technique was demonstrated through volumetric FLIM of a green fluorescent protein (GFP) labeled zebrafish embryo heart, of multi-fluorescent protein (multi-FP) labeled plant root structures and of dynamic cardiac cycles in live zebrafish embryos. For the latter, we recorded the cardiac cycle dynamics of a zebrafish embryo at 50 frames per second and measured biomechanical parameters such as heart rate, ventricle/atrium areas, atrioventricular valve dynamics, and fractional area change. Taken together, these studies show the capability of the system for rapid, high resolution, and functional imaging in diverse biological contexts.

bioengineering↗

bioRxiv2026

In transected nerves, distal repair Schwann cells are required at the injury site to direct and accelerate axonal regrowth

In vertebrate peripheral nerves, damaged axons can regrow after injury, but the outcomes of regeneration are variable and often incomplete. Schwann cells in injured nerves are important for repair, but their actions at different positions and stages of nerve repair are not well understood. We have investigated the roles of Schwann cells in a larval zebrafish nerve injury model, in which nerves are visible in living animals during development, the initial injury response, and regrowth of the transected axons. After mechanical injury, distal Schwann cells adopt a repair phenotype characterized by changes in marker expression, elongation, and ability to guide axons across the injury site. In contrast, proximal Schwann cells are not sufficient to guide axons across the injury site, and they associate with axons that regrow along aberrant paths. In erbb2 mutants lacking Schwann cells, developmental axon growth is normal, but after transection, axonal regrowth is greatly slowed and often misdirected. By examining animals with nerves partially populated by Schwann cells, we find that axons can regrow through regions devoid of Schwann cells, provided that at least one distal Schwann cell is at the injury site. Timelapse imaging reveals that distal Schwann cells extend processes toward the injury site, which contact and guide axons regrowing from the proximal nerve stump. In irf8 mutants lacking macrophages, debris from transected axons is cleared on schedule, and axonal regrowth is normal. Our studies demonstrate that Schwann cells immediately distal to the injury site have a unique and essential role in axonal regrowth. Main PointsO_LIAfter nerve transection in larval zebrafish, proximal and distal Schwann cells have distinct functions at injury site C_LIO_LIA single distal repair Schwann cell is sufficient for axonal regrowth C_LIO_LIAxonal regrowth is normal in mutants without macrophages C_LI

neuroscience↗

bioRxiv2023

Oligodendrocyte Development and Myelin Sheath Formation are Regulated by the Antagonistic Interaction between the Rag-Ragulator Complex and TFEB

Myelination by oligodendrocytes is critical for fast axonal conduction and for the support and survival of neurons in the central nervous system. Recent studies have emphasized that myelination is plastic and that new myelin is formed throughout life. Nonetheless, the mechanisms that regulate the number, length, and location of myelin sheaths formed by individual oligodendrocytes are incompletely understood. Previous work showed that lysosomal transcription factor TFEB represses myelination by oligodendrocytes and that the RagA GTPase inhibits TFEB, but the step or steps of myelination in which TFEB plays a role have remained unclear. Here, we show that TFEB regulates oligodendrocyte differentiation and also controls the number and length of myelin sheaths formed by individual oligodendrocytes. In the dorsal spinal cord of tfeb mutants, individual oligodendrocytes produce fewer myelin sheaths, and these sheaths are longer than those produced by wildtype cells. Transmission electron microscopy shows that there are more myelinated axons in the dorsal spinal cord of tfeb mutants than in wildtype animals, but no significant change in axon diameter. In contrast to tfeb mutants, oligodendrocytes in rraga mutants produce shorter myelin sheaths. The sheath length in rraga; tfeb double mutants is not significantly different from wildtype, consistent with the antagonistic interaction between RagA and TFEB. Finally, we find that the GTPase activating protein Flcn and the RagCa and RagCb GTPases are also necessary for myelination by oligodendrocytes. These findings demonstrate that TFEB coordinates myelin sheath length and number during myelin formation in the central nervous system. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/530892v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@ed69a7org.highwire.dtl.DTLVardef@b35577org.highwire.dtl.DTLVardef@1b0389dorg.highwire.dtl.DTLVardef@54e3e0_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗

bioRxiv2022

Unmyelinated neurons use Neuregulin signals to promote myelination of neighboring neurons in the CNS

The signaling mechanisms neurons use to modulate myelination of circuits in the central nervous system (CNS) are only partly understood. Through analysis of isoform-specific neuregulin1 (nrg1) mutants, we identify nrg1 type II as an important regulator of myelination in the zebrafish CNS, required for normal myelination of two classes of spinal cord neurons. Surprisingly, nrg1 type II reporter expression is prominent in unmyelinated Rohon-Beard (RB) sensory neurons, while myelination of interneurons controlling the escape response circuit is reduced in nrg1 type II mutants. Cell type-specific loss-of-function studies indicate that nrg1 type II is required in RB neurons to signal to other neurons, not oligodendrocytes, to modulate spinal cord myelination. Together, our data support a model in which unmyelinated neurons express Nrg1 type II proteins to regulate myelination of circuit partners, a mode of action that may coordinate function of circuits in the CNS involving both unmyelinated and myelinated neurons. Summary pointsO_LInrg1 type II is required for normal myelination of diverse neuronal classes in the zebrafish spinal cord C_LIO_LISurprisingly, nrg1 type II reporter expression is prominent in unmyelinated Rohon-Beard neurons C_LIO_LICell type-specific knockdown indicates that myelination of CoPA neurons requires nrg1 type II function in unmyelinated Rohon-Beard neurons C_LIO_LIThe Nrg1 receptor erbb2 is required in neurons, but not oligodendrocytes, for normal myelination C_LI

developmental biology↗

bioRxiv2021

Characterization of mouse Bmp5 regulatory injury element in zebrafish wound models

Many key signaling molecules used to build tissues during embryonic development are re-activated at injury sites to stimulate tissue regeneration and repair. Bone morphogenetic proteins provide a classic example, but the mechanisms that lead to reactivation of BMPs following injury are still unknown. Previous studies have mapped a large "injury response element" (IRE) in the mouse Bmp5 gene that drives gene expression following bone fractures and other types of injury. Here we show that the large mouse IRE region is also activated in both zebrafish tail resection and mechanosensory hair cell injury models. Using the ability to test multiple constructs and image temporal and spatial dynamics following injury responses, we have narrowed the original size of the mouse IRE region by over 100 fold and identified a small 142 bp minimal enhancer that is rapidly induced in both mesenchymal and epithelial tissues after injury. These studies identify a small sequence that responds to evolutionarily conserved local signals in wounded tissues and suggest candidate pathways that contribute to BMP reactivation after injury.

developmental biology↗

bioRxiv2020

Repression of lysosomal transcription factors Tfeb and Tfe3 is essential for the development and function of microglia

As the primary phagocytic cells of the central nervous system, microglia exquisitely regulate their lysosomal activity to facilitate brain development and homeostasis. However, mechanisms that coordinate lysosomal activity with microglia development, migration, and function remain unclear. Here we show that embryonic macrophages require the lysosomal GTPase RagA and the GTPase-activating protein Folliculin to colonize the brain in zebrafish. We demonstrate that embryonic macrophages in rraga mutants show increased expression of lysosomal genes but display significant downregulation of immune and migration-related genes. Furthermore, we find that RagA and Folliculin repress the key lysosomal transcription factor Tfeb, and its homologs Tfe3a and Tfe3b, in the macrophage lineage. Using RNA-Sequencing, we establish that Tfeb and Tfe3 are required for activation of lysosomal target genes under conditions of stress but not for basal expression of lysosomal pathways. Collectively, our data define a lysosomal regulatory circuit essential for macrophage development and function in vivo. TeaserThe degradation machinery of the cell must be carefully controlled for the normal formation and function of key immune cells called microglia.

developmental biology↗

bioRxiv2020

Synaptic vesicle fusion along axons is driven by myelination and subsequently accelerates sheath growth in an activity-regulated manner

To study activity-regulated myelination, we imaged synaptic vesicle fusion along single axons in living zebrafish, and found, surprisingly, that axonal synaptic vesicle fusion is driven by myelination. This myelin-induced axonal vesicle fusion was enriched along the unmyelinated domains into which newly-formed sheaths grew, and was promoted by neuronal activity, which in turn accelerated sheath growth. Our results indicate that neuronal activity consolidates sheath growth along axons already selected for myelination.

neuroscience↗