Biology subjects

Moreira, C.

Publications and source records attributed to Moreira, C..

3 recordsLinked to original sources

bioRxiv2024

Paced Breathing With a Prolonged Inspiratory Period Increases Sympathetic Activity: A Heart and Brain Analysis

Paced breathing exercises with prolonged exhalation have been commonly used to reduce stress and anxiety by stimulating parasympathetic activity. However, increasing sympathetic activity may also provide benefits such as increased alertness and energy levels. In this work, we investigate the physiological impact of an 80-second breathing exercise with a prolonged inspiratory period of 6 seconds followed by 2 seconds of exhalation on the sympathetic system. We collected raw two-channel prefrontal electroencephalography and photoplethysmography signals of 19 subjects using EMOTAIs headband while performing the proposed exercise every workday for 2 weeks straight. Physiological metrics such as heart rate, heart rate variability, and absolute power of the brain waves were extracted before and during the exercise to measure its effectiveness. A marked increase in beta wave power was observed, along with a significant increase in both heart rate and heart rate variability. The cardiovascular results indicate that the proposed exercise effectively raised sympathetic activity. Simultaneously, the observed neural activity is consistent with that seen during focused attention and heightened mental processing.

physiology↗

bioRxiv2024

The N-terminal helix of MarA as a key element in the mechanism of DNA binding

Efflux is one of the mechanisms employed by Gram-negative bacteria to become resistant to routinely used antibiotics. The inhibition of efflux by targeting their regulators is a promising strategy to re-sensitise bacterial pathogens to antibiotics. AcrAB-TolC is the main Resistance-Nodulation-Division efflux pump in Enterobacteriaceae. MarA is an AraC/XylS family global regulator that regulates more than 40 genes related to the antimicrobial resistance phenotype, including acrAB. The aim of this work was to understand the role of the N-terminal helix of MarA in the mechanism of DNA binding. An N-terminal deletion of MarA showed that the N-terminal helix has a role in the recognition of the functional marboxes. By engineering two double cysteine variants of MarA, and combining in vitro electrophoretic mobility assays and in vivo measurements of acrAB transcription with molecular dynamic simulations, it was shown that the immobilization of the N-terminal helix of MarA prevents binding to DNA. This new mechanism of inhibition seems to be universal for the monomeric members of the AraC/XylS family, as suggested by additional molecular dynamics simulations of the two-domain protein Rob. These results point to the N-terminal helix of the AraC/XylS family monomeric regulators as a promising target for the development of inhibitors.

molecular biology↗

bioRxiv2019

Population structure determined by comparative amplicon gene sequencing in biofilm and planktonic bacterial communities from pesticide-contaminated water

Molecular and bioinformatics tools for research are very important for biodiversity characterization in contaminated environments due the presence of a high percentage of nonculturable microorganisms. The wide use of pesticides in agriculture exposes microbiomes to stressful and selective conditions that demand survival strategies such as biofilm formation. The purpose of this work was to evaluate the bacterial population structure in planktonic and biofilm communities of water that was used for washing the packaging of herbicides and stored for six months in tanks. This substance is highly contaminated waste. Samples of water and biofilms from tanks and biofilms developed for short times in flasks were used for DNA isolation and 16S rRNA gene sequencing. The physicochemical conditions imposed by water used for washing the containers were inadequate for killing the bacterial genera identified according to water and wastewater standards. The variation in population structure and diversity was lower in the planktonic samples than in the biofilm samples, indicating a possible combination of genetic drift and subsequent selection of individuals surviving under stressful water conditions, such as heating and contact with agrochemicals, over a six-month period. The biofilm formation in water tanks contaminated with pesticides enabled the survival of bacterial genera harboring the essential processes for adaptation to these environments; the presence of these processes was determined according to descriptions obtained from the genomic databases. This study suggests the potential of bacterial genera identified in biofilms obtained from tanks to adapt to contaminated environments through their metabolic complexity. Thus, herbicide biodegradation kinetics can be accessed through a culturable collection obtained from these communities.

microbiology↗