Biology subjects

Post, M.

Publications and source records attributed to Post, M..

6 recordsLinked to original sources

bioRxiv2026

Evaluation of gaseous ozone technology for decontaminating porcine reproductive and respiratory syndrome virus (PRRSV) and porcine epidemic diarrhea virus (PEDV) from non-porous surface in truck cabins

Porcine reproductive and respiratory syndrome virus (PRRSV) and porcine epidemic diarrhea virus (PEDV), both economically detrimental to the swine industry, can be spread through contaminated truck cabins, posing significant transport biosecurity risks. This study evaluated the effectiveness of gaseous ozone technology in decontaminating PRRSV and PEDV on non-porous surfaces in truck cabins. An incomplete factorial study comprising 26 treatment groups, including controls, and ozone treatments at three capacities (30, 38, and 68 g/h) was conducted over varied exposure times (0.5, 1, or 2 hours) in a climate-controlled truck cabin, where PRRSV or PEDV contaminated rubber coupons were subjected to treatments under continuous environmental monitoring, followed by virus elution and titration in cell cultures. Statistical analyses included regression models and ANOVA with Tukey's comparisons, standard deviations for ozone machines, and Pearson correlations between ozone concentration and environmental factors. Ozone treatments showed variable results with less than two-log viral titer reduction. Ozone concentrations varied across identical setups (SD: 4.75 ppm for 30 g/h, 5.43 ppm for 38 g/h machines) during the first 30 minutes, while across the entire study period, ozone concentration showed weak negative correlation with virus titer (p > 0.05), moderate positive correlation with temperature (r = 0.5, p < 0.0001), and moderate negative correlation with humidity (r = -0.56, p < 0.0001). In conclusion, ozone treatments showed inconsistent and limited effectiveness in PRRSV and PEDV decontamination, influenced by temperature and humidity under the tested conditions.

microbiology↗

bioRxiv2024

Large herbivores link plant phenology and abundance in arctic tundra

Plant phenology has been well studied in relation to abiotic conditions and climate change, but poorly studied in relation to herbivory. In contrast, plant abundance dynamics have been well studied in relation to abiotic conditions and herbivory, but poorly studied in relation to phenology. Consequently, the contribution of herbivory to plant phenological dynamics and therefrom to plant abundance dynamics remains obscure. We conducted a nine-year herbivore exclusion experiment to investigate whether herbivory might link plant phenological and abundance dynamics in arctic tundra. From 2009 - 2017 we monitored annual green-up timing and abundance of nine plant taxa, including deciduous shrubs, forbs, and graminoids, on plots that were either grazed or experimentally exclosed from herbivory by caribou (Rangifer tarandus) and muskoxen (Ovibos moschatus). In 62% of cases, green-up occurred earlier under herbivory, and in 75% of cases abundance was greater under herbivory, compared to green-up and abundance under herbivore exclusion. Moreover, taxa that responded to herbivory with earlier green-up also had comparatively greater abundance later in the growing season. Conversely, taxa that responded to herbivory with delayed green-up exhibited comparatively lower abundance later in the growing season. Hence, well-documented influences of large herbivores on plant abundance and community composition in arctic tundra may, at least to some extent, relate to influences of herbivory on plant phenology. We recommend that ongoing and future assessments of the contribution of herbivores to plant abundance and community responses to climate change, especially in the Arctic, should also consider impacts of herbivores on plant phenology.

ecology↗

bioRxiv2024

In Vivo Plasmonic Enhancement of the Photocycle Dynamics and Fluorescence of Genetically Encoded Voltage Indicators

Plasmonic nanoparticles are key components in nanophotonics1-11 and have applications in molecular detection and diagnostic platforms. 12-14 Coupling of dipoles to plasmonic antennas has allowed engineering of qualitatively altered behavior in isolated quantum systems, 8,15 but this promise has not been fulfilled in living systems, where the use of plasmonics is limited to tissue level applications of plasmonic particles as contrast agents16 or heat sources.17 Here we show that coupling to designed plasmonic nanoparticles can control the electrophysiological function of proteins in living cells. We designed nanostar geometries and achieved robust near-field coupling of these optimized nanoparticles to plasma membrane-localized Archaerhodopsin proteins. We enhanced the fluorescence of the coupled rhodopsins and increased their response speed to membrane voltage. We incorporated this plasmonic enhancement into a Markov chain photocycle model of the Archaerhodopsin mutant QuasAr6a, showing an increased fluorescence emission rate and manipulation of the protein dynamics through a combination of photocycle transition rate enhancements. These results represent the first scalable near-field coupling between plasmonic particles and fluorescent proteins in living cells. They show enhancement of protein function beyond what has been achievable through genetic engineering. This opens up a range of possibilities for engineering biological functionality through plasmonics.

biophysics↗

bioRxiv2022

Autophagy is impaired in fetal hypoplastic lungs and rescued by administration of amniotic fluid stem cell extracellular vesicles

RationalePulmonary hypoplasia secondary to congenital diaphragmatic hernia (CDH) is characterized by reduced branching morphogenesis, which is responsible for poor clinical outcomes. Administration of amniotic fluid stem cell extracellular vesicles (AFSC-EVs) rescues branching morphogenesis in rodent fetal models of pulmonary hypoplasia. Herein, we hypothesized that AFSC-EVs exert their regenerative potential by affecting autophagy, a process required for normal lung development. ObjectivesTo evaluate autophagy in hypoplastic lungs throughout gestation and establish whether AFSC-EV administration improves branching morphogenesis through autophagy-mediated mechanisms. MethodsEVs were isolated from c-kit+ AFSC conditioned medium by ultracentrifugation and characterized for size, morphology, and EV markers. Branching morphogenesis was inhibited in rat fetuses by nitrofen administration to dams and in human fetal lung explants by blocking RAC1 activity with NSC23766. Expression of autophagy activators (BECN1 and ATG5) and adaptor (SQSTM1/p62) was analyzed in vitro (rat and human fetal lung explants) and in vivo (rat fetal lungs). Mechanistic studies on rat fetal primary lung epithelial cells were conducted using inhibitors for microRNA-17 and -20a contained in the AFSC-EV cargo and known to regulate autophagy. Measurements and Main ResultsRat and human models of fetal pulmonary hypoplasia showed reduced autophagy mainly at pseudoglandular and canalicular stages. AFSC-EV administration restored autophagy in both pulmonary hypoplasia models by transferring miR-17[~]92 cluster members contained in the EV cargo. ConclusionsAFSC-EV treatment rescues branching morphogenesis partly by restoring autophagy through miRNA cargo transfer. This study enhances our understanding of pulmonary hypoplasia pathogenesis and creates new opportunities for fetal therapeutic intervention in CDH babies.

developmental biology↗

bioRxiv2021

Cooperative protein allosteric transition mediated by a fluctuating transmission network

Allosteric communication between distant protein sites represents a key mechanism of biomolecular regulation and signal transduction. Compared to other processes such as protein folding, however, the dynamical evolution of allosteric transitions is still not well understood. As example of allosteric coupling between distant protein regions, we consider the global open-closed motion of the two domains of T4 lysozyme, which is triggered by local motion in the hinge region. Combining extensive molecular dynamics simulations with a correlation analysis of interresidue contacts, we identify a network of interresidue distances that move in a concerted manner. The cooperative process originates from a cogwheel-like motion of the hydrophobic core in the hinge region, which constitutes a flexible transmission network. Through rigid contacts and the protein backbone, the small local changes of the hydrophobic core are passed on to the distant terminal domains and lead to the emergence of a rare global conformational transition. As in an Ising-type model, the cooperativity of the allosteric transition can be explained via the interaction of local fluctuations.

biophysics↗

bioRxiv2019

mTOR suppresses macroautophagy during postnatal development of the striatum.

Macroautophagy (hereafter referred to as autophagy) plays a critical role in neuronal function related to development and degeneration. Here, we investigated whether autophagy is developmentally regulated in the striatum, a brain region implicated in neurodevelopmental disease. We demonstrate that autophagic flux is suppressed during striatal postnatal development, reaching adult levels around postnatal day 28 (P28). We also find that mTOR signaling, a key regulator of autophagy, increases during the same developmental period. We further show that mTOR signaling is responsible for suppressing autophagy, via regulation of Beclin-1 and VPS34 activity. These results demonstrate that neurons coopt metabolic signaling cascades to developmentally regulate autophagy and establish mTOR as a central node in the regulation of neuronal autophagy.

neuroscience↗