Biology subjects

Almeida, L. M.

Publications and source records attributed to Almeida, L. M..

3 recordsLinked to original sources

bioRxiv2026

Mobilome of Enterococcus faecalis from healthy nursery pigs exposed to antibiotic pressure

In response to the comparatively sudden application of industrial scale levels of antibiotics to an ecosystem where naturally produced antibiotics are scarce, namely the ecologies within and around agricultural settings, animal-associated microbes have had to rapidly adapt, mostly relying on mobile genetic elements (MGEs) taken up due to loss of CRISPR functionality. Due to selection for resistance and other adaptive traits carried by dynamic and rapidly recombining MGEs, plasmids and transposons have rapidly accumulated in this human-proximal environment. Because of the occurrence of Enterococcus faecalis in a wide range of hosts up and down the food chain, and the fact that this species represents the greatest generalist of the genus, we comprehensively examined the mobilome of multidrug-resistant E. faecalis (ST330, ST591, ST710, and ST711) from healthy piglets raised on dispersed Brazilian farms, using long-read sequencing, analysis of plasmid pangenomes, and conjugation assays with these strains serving as donors. Genomes ranged from [~]2.8-3.1 Mb, with diverse MGEs constituting [~]7-15% of those genomes. Large modular antimicrobial resistance-encoding gene blocks ([~]40 Kb) were observed to be integrated into a [~]67 Kb chromosomal segment of the pathogenicity island AF454824. Prophages contributed up to 70% of the chromosomal mobile element content, integrating into both CRISPR-deficient genomes and those with intact type II-A CRISPR1 arrays, which were enriched with Caudoviricetes phage-targeting spacers across all strains. Plasmid content showed pronounced mosaicism driven by diverse insertion sequences, transposons, and related mobile elements, many directly implicated in AMR gene cluster acquisitions. RepA_N, Inc18, and Rep3 plasmids, mostly conjugative, also carried various persistence-related traits, suggesting they may actively enhance agricultural fitness rather than passively accumulate due to loss of CRISPR protection.

microbiology↗

bioRxiv2026

Inhibition of the mitochondrial pyruvate carrier attenuates the integrated stress response activation in a cellular model of Huntington's disease

Mitochondrial pyruvate carrier (MPC) inhibition was found protective in models of neurodegenerative diseases, such as Alzheimers and Parkinsons. However, little is known about MPC as a potential therapeutic target in Huntingtons disease (HD), a neurodegenerative disorder with dysregulation of the pro-survival pathway integrated stress response (ISR). Here, we investigate if MPC inhibition modulates the ISR and mitigates mutant huntingtin (mut-Htt) proteotoxicity in a cellular HD model. We treated cells expressing N-terminal fragments of wild-type- (wt-) or mut-Htt with two MPC inhibitors (mitoglitazone and UK5099) or solvent control. Metabolism was assessed analysing resazurin reduction, oxygen consumption, extracellular acidification, and ATP levels. ISR activation and huntingtin proteostasis were assessed using western-blot and filter-trap assays. Mut-Htt-expressing cells showed decreased resazurin reduction and ATP levels, and increased eIF2 phosphorylation, indicating metabolic stress and ISR activation. MPC inhibitors (100 {micro}M) increased resazurin reduction and decreased respiration. The latter was rescued by the membrane-permeant methyl pyruvate, which bypasses MPC inhibition. In wt-Htt-expressing cells, MPC inhibitors increased levels of ATP and ISR markers, suggesting metabolic adaptation and ISR activation. In mut-Htt-expressing cells, MPC inhibitors preserved ATP levels and attenuated mut-Htt-induced eIF2 phosphorylation but without changing soluble or aggregated mut-Htt levels. This work showed that MPC inhibition differentially modulates the ISR: it activates ISR in control cells and attenuates overactive ISR in mut-Htt-expressing cells. However, MPC inhibition did not impact the proteostasis of N-terminal fragment mut-Htt. Further studies are essential to explore MPC inhibition in less severe full-length mut-Htt-expressing models to better understand its therapeutic potential in HD.

pharmacology and toxicology↗

bioRxiv2024

PERK inhibition in zebrafish mimics human Wolcott-Rallison syndrome phenotypes

BackgroundPERK (EIF2AK3) is an endoplasmic reticulum stress kinase whose loss of function disturbs human development, leading to skeletal dysplasia and permanent neonatal diabetes, as observed in the Wolcott-Rallison Syndrome (WRS). The lack of effective, less invasive therapies for developmental diseases highlights the need for animal models that replicate complex pathological phenotypes, while allowing scalable drug screening. Zebrafish, with their high fecundity and rapid development, facilitate efficient in vivo drug testing. MethodsWe aimed to assess the potential of zebrafish for studying PERK function and its pharmacological modulation, particularly as a model for developmental diseases like WRS. Bioinformatic analyses assessed the similarity between human and zebrafish PERK. Increasing concentrations of GSK2606414 were used to inhibit PERK. A combination of behavioural and functional assays evaluated the effects of GSK2606414 on zebrafish skeletal, neuromuscular, and cardiac development. Fluorescence microscopy in transgenic zebrafish expressing fluorescent pancreatic markers and a glucose probe assessed the diabetic-like phenotype. ResultsWe found high similarity between human and zebrafish PERK, along with bioactivity of the PERK inhibitor GSK2606414 in zebrafish. PERK inhibition evoked defects in WRS relevant parameters, such as growth and skeletal development, as well as neuromuscular and cardiac deficiencies, whereas parameters not associated with WRS like otolith area and eye/body ratio remained unaffected. Moreover, PERK inhibition decreased pancreatic ! cell mass and disrupted glucose homeostasis, indicating a diabetic phenotype. ConclusionThese findings evidence zebrafishs potential for studying PERK function and its pharmacological modulation in developmental disorders like WRS, aiding research on pathophysiology and experimental treatments.

pharmacology and toxicology↗