Williams, G. C. | Search bioRxiv

bioRxiv2025

Bacterial species and surface structures shape gene transfer and the transcriptional landscape during early conjugation

Conjugative plasmids drive bacterial evolution and niche adaptation, yet how their active acquisition reshapes host transcription remains poorly understood. Most studies focus on stable plasmid carriage, overlooking the dynamic transcriptional changes during conjugation itself. Here, we show that active RP4 conjugation triggers an immediate, host- and surface factor-dependent transcriptional response. This includes activation of non-SOS stress pathways, motility, exopolysaccharide production, anaerobic respiration, and metabolic adaptation. These responses do not inhibit conjugation, suggesting they serve to maintain host homeostasis. Capsule expression blocks these responses by preventing conjugation, and also inhibits RP4 activation by physically blocking donor-recipient contact. Unexpectedly, RP4 overcomes this barrier by exploiting single-cell variation in recipient capsule thickness, successfully conjugating with thin-capsulated recipients. These findings reveal a striking interplay between plasmid, host, and surface architecture in shaping the conjugation transcriptional landscape, with broad implications for plasmid dissemination and bacterial evolution.

microbiology↗

bioRxiv2025

Feature-temporal predictions dynamically modulate performance, feature-based attentional capture, and motor response activity during visual search

Recent research has investigated visual search in dynamic environments and considered how temporal predictions modulate behaviour over time. Spatiotemporal predictions have been shown to adaptively guide behaviour during search to improve target detection at temporally-likely locations. The utility of non-spatial, feature-temporal predictions is less intuitive. The present study investigated whether and how behaviour may be guided toward feature-temporally predictable targets during visual search in crowded and dynamic displays. We tested 1) whether visual attention is guided toward target-relevant features in a temporally specific manner and 2) whether our motor system is temporally tuned accordingly. Participants searched for two distinct targets (non-overlapping colour-shape combinations) in a free-viewing dynamic visual-search task. During an initial learning session, each target identity appeared at a predictable time. In a following testing session, some targets appeared at unpredicted times. Targets locations were always unpredictable. We compared the efficiency of identifying targets appearing at predicted versus unpredicted times to test for performance benefits of feature-temporal predictability. In addition, we measured whether gaze fixation was captured by distractors that shared overlapping features with temporally predicted targets. Electromyography recordings were used to test for anticipatory muscle activity tuned to the timing of predictable targets. Results indicated that learning the task regularities led to dynamic modulation of participants efficiency at identifying targets, their feature-based attentional capture, and temporally tuned muscle activity. The work highlights the flexibility of temporal expectations in guiding behaviour even under spatial uncertainty.

animal behavior and cognition↗