Biology subjects

Misquitta, K.

Publications and source records attributed to Misquitta, K..

6 recordsLinked to original sources

bioRxiv2023

A fluorescence viewer for rapid molecular assay readout in space and low-resource terrestrial environments

Fluorescence-based assays provide sensitive and adaptable methods for point of care testing, environmental monitoring, studies of protein abundance and activity, and a wide variety of additional applications. Currently, their utility in remote and low-resource environments is limited by the need for technically complicated or expensive instruments to read out fluorescence signal. Here we describe the Genes in Space Fluorescence Viewer (GiS Viewer), a portable, durable viewer for rapid molecular assay readout that can be used to visualize fluorescence in the red and green ranges. The GiS Viewer can be used to visualize any assay run in standard PCR tubes and contains a heating element. Results are visible by eye or can be imaged with a smartphone or tablet for downstream quantification. We demonstrate the capabilities of the GiS Viewer using two case studies - detection of SARS-CoV-2 RNA using RT-LAMP and quantification of drug-induced changes in gene expression via qRT-PCR on Earth and aboard the International Space Station. We show that the GiS Viewer provides a reliable method to visualize fluorescence in space without the need to return samples to Earth and can further be used to assess the results of RT-LAMP and qRT-PCR assays on Earth.

molecular biology↗

bioRxiv2020

Chronic stress induces coordinated cortical microcircuit cell type transcriptomic changes consistent with altered information processing

Major depressive disorder (MDD) is associated with altered GABAergic and glutamatergic signalling, suggesting altered excitation-inhibition balance (EIB) in cortical mood- and cognition-regulating brain regions. Information processing in cortical microcircuits involves regulation of pyramidal (PYR) cells by Somatostatin-(SST), Parvalbumin-(PV), and Vasoactive intestinal peptide-(VIP) expressing interneurons. Human and rodent studies suggest that impaired PYR-cell dendritic morphology and decreased SST-cell function may mediate altered EIB in MDD. However, knowledge of co-ordinated changes across microcircuit cell types is virtually absent. We thus investigated the co-ordinated transcriptomic effects of UCMS on microcircuit cell types in the medial prefrontal cortex. C57Bl/6 mice, exposed to unpredictable chronic mild stress (UCMS) or control housing for five weeks were assessed for anxiety- and depressive-like behaviours. Microcircuit cell types were laser-microdissected and processed for RNA-sequencing. UCMS-exposed mice displayed predicted elevated behavioural emotionality. Each microcircuit cell type showed a unique transcriptional signature after UCMS. Pre-synaptic functions, oxidative stress response, metabolism, and translational regulation were differentially dysregulated across cell types, whereas nearly all cell types showed down-regulated post-synaptic gene signatures. At the microcircuit level, we observed a shift from distributed transcriptomic co-ordination across cell types in controls towards UCMS-induced increased co-ordination between PYR-, SST- and PV-cells, and a hub-like role for PYR-cells. Lastly, we identified a microcircuit-wide co-expression network enriched in synaptic, bioenergetic, and oxidative stress response genes that correlated with UCMS-induced behaviours. Together, these findings suggest cell-specific deficits, microcircuit-wide synaptic reorganization, and a shift in cortical EIB mediated by increased co-ordinated regulation of PYR-cells by SST- and PV-cells.

neuroscience↗

bioRxiv2020

Prophylactic efficacy of riluzole against anxiety- and depressive-like behaviors in two rodent stress models

BackgroundChronic stress-related illnesses, such as major depressive disorder and post-traumatic stress disorder share symptomatology, including anxiety, anhedonia, and helplessness. Across disorders, neurotoxic dysregulated glutamate (Glu) signaling may underlie symptom emergence. Current first-line antidepressant drugs, which do not directly target Glu signaling, fail to provide adequate benefit for many patients and are associated with high relapse rates. Riluzole modulates glutamatergic neurotransmission by increasing metabolic cycling and modulating signal transduction. Clinical studies exploring riluzoles efficacy in stress-related disorders have provided varied results. However, the utility of riluzole for treating specific symptom dimensions or as a prophylactic treatment has not been comprehensively assessed. MethodsWe investigated whether chronic prophylactic riluzole (~12-15mg/kg/day p.o.) could prevent the emergence of behavioral deficits induced by unpredictable chronic mild stress (UCMS) in mice. We assessed: i) anxiety-like behavior using the elevated-plus maze, open field test, and novelty-suppressed feeding, ii) mixed anxiety/anhedonia-like behavior in the novelty-induced hypophagia test and, iii) anhedonia-like behavior using the sucrose consumption test. Z-scoring summarized changes across tests measuring similar dimensions. In a separate learned helplessness (LH) cohort, we investigated whether chronic prophylactic riluzole treatment could block the development of helplessness-like behavior. ResultsUCMS induced an elevation in anhedonia-like behavior, and overall behavioral emotionality that was blocked by prophylactic riluzole. In the LH cohort, prophylactic riluzole blocked the development of helplessness-like behavior. ConclusionThis study supports the utility of riluzole as a prophylactic medication for preventing anhedonia, and helplessness symptoms associated with stress-related disorders.

pharmacology and toxicology↗

bioRxiv2020

Chronic stress exacerbates acute stress-induced neuronal activation in the anterior cingulate cortex and ventral hippocampus that correlates with behavioral deficits in mice

Altered activity of corticolimbic brain regions is a hallmark of stress-related illnesses, including mood disorders, neurodegenerative diseases, and substance abuse disorders. Acute stress adaptively recruits brain region-specific functions for coping, while sustained activation under chronic stress may overwhelm feedback mechanisms and lead to pathological cellular and behavioral responses. The neural mechanisms underlying dysregulated stress response and how they contribute to behavioral deficits are poorly characterized. Here, we tested whether prior exposure to chronic restraint stress (CRS) or unpredictable chronic mild stress (UCMS) in mice could alter neuronal response to acute stress and whether these changes are associated with chronic stress-induced behavioral deficits. More specifically, we assessed neuronal activation indexed by c-Fos+ cell counts in 24 stress- and mood-related brain regions, and determined if changes in acute stress-induced neuronal activation were linked to chronic stress-induced behavioral impairments. Results indicated that CRS and UCMS led to convergent physiological and anxiety-like deficits, whereas cognition was impaired only in UCMS mice. CRS and UCMS exposure exacerbated neuronal activation in response to an acute stressor in anterior cingulate cortex (ACC) area 24b and ventral hippocampal (vHPC) CA1, CA3, and subiculum. In dysregulated brain regions, levels of neuronal activation were positively correlated with principal components capturing variance across widespread behavioral alterations relevant to stress-related disorders. Our data supports an association between a dysregulated stress response, altered corticolimbic excitation/inhibition balance, and the expression of maladaptive behaviors. HighlightsO_LIChronic stress models produce variable profiles of physiological deficits, anxiety-like behavior, and impaired cognition C_LIO_LIAcute stress-induced activation of ACC A24b & vHPC is exacerbated by prior chronic stress exposure C_LIO_LIIn regions dysregulated by chronic stress, altered neuronal activation is positively correlated with behavioral deficits C_LI

neuroscience↗

bioRxiv2019

White matter hyperintensities and neuropsychiatric symptoms in Alzheimer’s disease and mild cognitive impairment

Background and Purpose: Neuropsychiatric symptoms (NPS) are frequently encountered in patients with Alzheimers disease (AD). Focal grey matter atrophy has been linked to NPS development. Cerebrovascular disease can cause focal lesions and is common among AD patients. As cerebrovascular disease can be detected on MRI as white matter hyperintensities (WMH), this study evaluated WMH burden in mild cognitive impairment (MCI), AD and normal controls and determined their relationship with NPS. Methods: NPS were assessed using the Neuropsychiatric Inventory and grouped into subsyndromes. WMH were measured using an automatic segmentation technique and mean deformation-based morphometry was used to measure atrophy of grey matter regions. Results: WMHs and grey matter atrophy both contributed significantly to NPS subsyndromes in MCI and AD subjects, however, WMH burden played a greater role. Conclusions: This study could provide a better understanding of the pathophysiology of NPS in AD.

neuroscience↗

bioRxiv2018

The relationship between brain atrophy and cognitive-behavioral symptoms in retired Canadian football players with multiple concussions

Multiple concussions, particularly in contact sports, have been associated with cognitive deficits, psychiatric impairment and neurodegenerative diseases like chronic traumatic encephalopathy. We used volumetric and deformation-based morphometric analyses to test the hypothesis that repeated concussions may be associated with smaller regional brain volumes, poorer cognitive performance and behavioural symptoms among former professional football players compared to healthy controls. This study included fifty-three retired Canadian Football League players, 25 age- and education-matched healthy controls, and controls from the Cambridge Centre for Aging and Neuroscience database for validation. Volumetric analyses revealed greater hippocampal atrophy than expected for age in former athletes with multiple concussions than controls and smaller left hippocampal volume was associated with poorer verbal memory performance. Deformation-based morphometric confirmed smaller bilateral hippocampal volume that were associated with poorer verbal memory performance in athletes. Repeated concussions may lead to greater regional atrophy than expected for age.

neuroscience↗