Biology subjects

McGowan, E.

Publications and source records attributed to McGowan, E..

4 recordsLinked to original sources

bioRxiv2025

Synaptotagmin-7 is required for synchronous but not asynchronous facilitation of glutamate release at cortical boutons

Short-term synaptic plasticity and the kinetics of neurotransmitter release vary widely across synapses, but population measurements obscure the mechanisms that generate this diversity. While the Ca2+ sensor Synaptotagmin-7 (Syt7) has been implicated in facilitation, vesicle replenishment and asynchronous vesicle exocytosis, its precise contributions to these processes remain debated. We used quantal-resolution imaging to measure synchronous and asynchronous glutamate release at individual cortical boutons in wild type and Syt7-/- neurons. Stratifying boutons by release efficacy and applying failure-based analysis to isolate trials where the first action potential evoked no release allowed us to separate facilitation from vesicle depletion. Syt7 deletion selectively eliminated activity-dependent facilitation of synchronous release but left facilitation of asynchronous release intact, although its overall magnitude was reduced. We further show that synchronous and asynchronous events arise from functionally distinct vesicle populations. These findings demonstrate that activity-dependent facilitation of synchronous and asynchronous exocytosis are mechanistically separable, enabling synapses to independently tune distinct temporal components of neurotransmission.

neuroscience↗

bioRxiv2022

Uncertainty revealed by delayed responses during olfactory matching

Matching of olfactory stimuli involves both sensory and higher cognitive functioning. Different decision processes such as detection and discrimination, along with holding the perceived information are involved during the matching process. Accuracy and decision times, the interdependent readouts, can define the uncertainty involved in matching of sensory stimuli. To probe sensory and cognitive functions involving olfactory system in human subjects, we have developed a novel olfactory matching paradigm using an automated custom-built olfactory-action meter. With precise and consistent odor delivery and real-time data analysis, our system automates the entire process without any intervention by the experimenter, making it suitable as a diagnostic tool for quantifying olfactory and neurocognitive fitness. In around 400 healthy human subjects, with mean detection accuracy of 90%, we observed significantly better olfactory matching performance for simple monomolecular odors, in comparison to complex binary odor mixtures. Odor matching accuracy declined significantly with the increase in odor complexity. Olfactory matching was more rapid when subjects made correct versus incorrect decisions, indicating perceptual certainty. Subjects also took longer matching time for complex odors compared to simple odor stimuli. Thus, olfactory matching that provides a combined readout of sensory and cognitive fitness, establishes a direct link between the performance accuracy and the certainty of decisions.

neuroscience↗

bioRxiv2021

Automated Spatially Targeted Optical Micro Proteomics (AutoSTOMP) 2.0 identifies proteins enriched within inflammatory lesions in tissue sections and human clinical biopsies.

Tissue microenvironment properties like blood flow, extracellular matrix or proximity to immune infiltrate are important regulators of cell biology. However, methods to study regional protein expression in context of the native tissue environment are limited. To address this need we have developed a novel approach to visualize, purify and measure proteins in situ using Automated Spatially Targeted Optical Micro Proteomics (AutoSTOMP) 2.0. We previously implemented AutoSTOMP to identify proteins localized to the vacuoles of obligate intracellular microbes at the 1-2 m scale within infected host cells1. Here we report custom codes in SikuliX to specify regions of heterogeneity in a tissue section and then biotin tag and identify proteins belonging to specific cell types or structures within those regions. To enrich biotinylated targets from fixed tissue samples we developed a biochemical protocol compatible with LC-MS. These tools were applied to a) identify inflammatory proteins expressed by CD68+ macrophages in rat cardiac infarcts and b) characterize inflammatory proteins enriched in IgG4+ lesions in esophageal tissue. These data indicate that AutoSTOMP is a flexible approach to determine regional protein expression in situ on a range of primary tissues and clinical biopsies where current tools are limited.

immunology↗

bioRxiv2020

Utilizing Computational Machine Learning Tools to Understand Immunogenic Breadth in the Context of a CD8 T-Cell Mediated HIV Response

Predictive models are becoming more and more commonplace as tools for candidate antigen discovery to meet the challenges of enabling epitope mapping of cohorts with diverse HLA properties. Here we build on the concept of using two key parameters, diversity metric of the HLA profile of individuals within a population and consideration of sequence diversity in the context of an individuals CD8 T-cell immune repertoire to assess the HIV proteome for defined regions of immunogenicity. Using this approach, Analysis of HLA adaptation and functional immunogenicity data enabled the identification of regions within the proteome that offer significant conservation, HLA recognition within a population, low prevalence of HLA adaptation and demonstrated immunogenicity. We believe this unique and novel approach to vaccine design that, in combination with in vitro functional assays, offers a bespoke pipeline for expedited and rational CD8 T-cell vaccine design for HIV and potentially other pathogens with the potential for both global and local coverage.

immunology↗