Biology subjects

Paiva, T. O.

Publications and source records attributed to Paiva, T. O..

3 recordsLinked to original sources

bioRxiv2024

Serotype switching in Pseudomonas aeruginosa ST111 enhances adhesion and virulence

Evolution of the highly successful and multidrug resistant clone ST111 in Pseudomonas aeruginosa involves serotype switching from O-antigen O4 to O12. How expression of a different O-antigen serotype alters pathogen physiology to enable global dissemination of this high-risk clone-type is not understood. Here, we engineered isogenic laboratory and clinical P. aeruginosa strains that express the different O-antigen gene clusters to assess the correlation of structural differences of O4 and O12 O-antigens to pathogen-relevant phenotypic traits. We show that serotype O12 is associated with enhanced adhesion, type IV pili dependent twitching motility, and tolerance to host defense molecules and serum. Moreover, we find that serotype O4 is less virulent compared to O12 in an acute murine pneumonia infection in terms of both colonization and survival rate. Finally, we find that these O-antigen effects may be explained by specific biophysical properties of the serotype repeat unit found in O4 and O12, and by differences in membrane stability between O4 and O12 expressing cells. The results demonstrate that differences in O-antigen sugar composition can directly affect P. aeruginosa pathogenicity traits, and provide a better understanding of the potential selective advantages that underlie serotype switching and emergence of serotype O12 ST111.

microbiology↗

bioRxiv2021

Feedback processing in attack and defense conflicts: a neurophysiological study

Despite being extensively modelled to explore decision making processes in economic tasks, there are no studies exploring the neurophysiological correlates of the Predator-Prey Game, a game theory paradigm designed to operationalize attack and defence conflicts. In the present study, we explored the relationship between the ERP components associated with feedback, namely feedback-related negativity (FRN) and feedback -elated P3b, and investment in an adapted version of the Predator-Prey Game (PPG), operationalizing attack and defence. Forty-seven (28 female) community-dwelling volunteers without history of neurological disease were recruited. Participants played the PPG game both as attackers and defenders while EEG signal was recorded with a 128 channels sensor net. Behavioural results showed that individuals tend to invest more and decide faster when playing in defence, rather than in attack. Electrophysiological data showed FRN to be sensitive to the valence of feedback, with increased amplitudes of FRN loss feedbacks. On the other hand, the P3b amplitudes were sensitive to the role, with increased amplitude for attack when compared with defence. The integration of the behavioural and ERP findings supports the theoretical model positing that attack elicits more deliberate and less automatic brain processes than defence.

neuroscience↗

bioRxiv2018

Disentangling the Role of Face Typicality and Affect in Emotional Face Processing: Self-reported and Electrophysiological Evidence

Typicality, or averageness, is one of the key features that influences face evaluation, but the role of this property in the perception of facial expressions of emotions is still not fully understood. Typical faces are usually considered more pleasant and trustworthy, and neuroimaging results suggest typicality modulates amygdala and fusiform activation, influencing face perception. At the same time, there is evidence that arousal is a key affective feature that modulates neural reactivity to emotional expressions. In this sense, it remains unclear whether the neural effects of typicality depend on altered perceptions of affect from facial expressions or if the effects of typicality and affect independently modulate face processing. The goal of this work was to dissociate the effects of typicality and affective properties, namely valence and arousal, in electrophysiological responses and self-reported ratings across several facial expressions of emotion. Two ERP components relevant for face processing were measured, the N170 and Vertex Positive Potential (VPP), complemented by subjective ratings of typicality, valence, and arousal, in a sample of 30 healthy young adults (21 female). The results point out to a modulation of the electrophysiological responses by arousal, regardless of the typicality or valence properties of the face. These findings suggest that previous findings of neural responses to typicality may be better explained by accounting for the subjective perception of arousal in facial expressions.

neuroscience↗