Biology subjects

Hunter, P.

Publications and source records attributed to Hunter, P..

4 recordsLinked to original sources

bioRxiv2023

Mapping the Organization and Morphology of Calcitonin Gene-Related Peptide (CGRP)-IR Axons in the Whole Mouse Stomach

Nociceptive afferent axons innervate the stomach and send signals to the brain and spinal cord. Peripheral nociceptive afferents can be detected with a variety of markers [e.g., substance P (SP) and calcitonin gene-related peptide (CGRP)]. We recently examined the topographical organization and morphology of SP-immunoreactive (SP-IR) axons in the whole mouse stomach muscular layer. However, the distribution and morphological structure of CGRP-IR axons remain unclear. We used immunohistochemistry labeling and applied a combination of imaging techniques, including confocal and Zeiss Imager M2 microscopy, Neurolucida 360 tracing, and integration of axon tracing data into a 3D stomach scaffold to characterize CGRP-IR axons and terminals in the whole mouse stomach muscular layers. We found that: 1) CGRP-IR axons formed extensive terminal networks in both ventral and dorsal stomachs. 2) CGRP-IR axons densely innervated the blood vessels. 3) CGRP-IR axons ran in parallel with the longitudinal and circular muscles. Some axons ran at angles through the muscular layers. 4) They also formed varicose terminal contacts with individual myenteric ganglion neurons. 5) CGRP-IR occurred in DiI-labeled gastric-projecting neurons in the dorsal root and vagal nodose ganglia, indicating CGRP-IR axons were visceral afferent axons. 6) CGRP-IR axons did not colocalize with tyrosine hydroxylase (TH) or vesicular acetylcholine transporter (VAChT) axons in the stomach, indicating CGRP-IR axons were not visceral efferent axons. 7) CGRP-IR axons were traced and integrated into a 3D stomach scaffold. For the first time, we provided a topographical distribution map of CGRP-IR axon innervation of the whole stomach muscular layers at the cellular/axonal/varicosity scale.

neuroscience↗

bioRxiv2022

Super-resolved imaging deciphers ligand dependent membrane behaviour of the onco-immunogenic CCR5 receptor.

The ability of tumors to establish a pro-tumorigenic microenvironment is becoming an important point of investigation in the search for new therapeutics. Tumors form microenvironments in part by the education of immune cells attracted via chemotactic axes such as that of CCR5-CCL5. Further, CCR5 upregulation by cancer cells, coupled with its association with pro-tumorigenic features such as drug-resistance and metastasis, has suggested CCR5 as a target for therapeutic inhibition. However, with several conformational "pools" being reported, phenotypic investigations must be capable of unveiling heterogeneity. Addressing this challenge, we performed structured illumination (SIM) and Partially TIRF coupled HILO (PaTCH) microscopy for super-resolution imaging and single-molecule imaging of CCR5 in fixed cells. Determining the positions of super-resolved CCR5 assemblies revealed a non-random spatial orientation. Further, intensity-tracking of assemblies revealed a distribution of molecular stoichiometries indicative of dimeric sub-units independent of CCL5 perturbation. These biophysical methods can provide important insights into the structure and function of onco-immunogenic receptors and a plethora of other biomolecules. HighlightsO_LIWe use SIM and novel PaTCH microscopy for precise bioimaging and single-molecule tracking of receptor protein CCR5 in model cell line C_LIO_LIBy tracking the position of CCR5 assemblies we conclude that they are clustered in the plasma membrane beyond a level expected from a random distribution C_LIO_LIWe use these high-precision data to determine molecular stoichiometries of CCR5 assemblies C_LI

biophysics↗

bioRxiv2020

3D single cell scale anatomical map of sex-dependent variability of the rat intrinsic cardiac nervous system

We developed and analyzed a single cell scale anatomical map of the rat intrinsic cardiac nervous system (ICNS) across 4 male and 3 female hearts. We find the ICNS has a reliable structural organizational plan across individuals that may provide the foundation for further analyses of the ICNS in cardiac function and disease. The distribution of the ICNS was evaluated by 3D visualization and using data-driven clustering. The pattern, distribution and clustering of ICNS neurons across all male and female rat hearts is highly conserved, demonstrating a coherent organizational plan in which distinct clusters of neurons are consistently localized. Female hearts had fewer neurons, lower packing density and slightly reduced distribution, but with the same localization. We registered the anatomical data from each heart to a geometric scaffold, normalizing their 3D coordinates for the standardization of common anatomical planes and providing the path where multiple experimental results and data types can be integrated and compared.

neuroscience↗

bioRxiv2017

Imaging and dynamic causal modelling reveal brain-wide changes in effective connectivity and synaptic dynamics during epileptic seizures.

Pathophysiological explanations of epilepsy typically focus on either the micro/mesoscale (e.g. excitation-inhibition imbalance), or on the macroscale (e.g. network architecture). Linking abnormalities across spatial scales remains difficult, partly because of technical limitations in measuring neuronal signatures concurrently at the scales involved. Here we use light sheet imaging of the larval zebrafish brain during acute epileptic seizure induced with pentylenetetrazole. Empirically measured spectral changes of spontaneous neuronal activity during the seizure are then modelled using neural mass models, allowing Bayesian inference on changes in effective network connectivity and their underlying synaptic dynamics. This dynamic causal modelling of seizures in the zebrafish brain reveals concurrent changes in synaptic coupling at macro- and mesoscale. Fluctuations of synaptic connection strength and their temporal dynamics are both required to explain observed seizure patterns. These findings challenge a simple excitation-inhibition account of seizures, and highlight changes in synaptic transmission dynamics as a possible seizure generation pathomechanism.\n\nAbbreviations

neuroscience↗