RESUMEN
Bacterial viruses (known as "phages") shape the ecology and evolution of microbial communities, making them promising targets for microbiome engineering. However, knowledge of phage biology is constrained because it remains difficult to study phage transmission dynamics within multi-member communities and living animal hosts. We therefore created "Phollow": a live imaging-based approach for tracking phage replication and spread in situ with single-virion resolution. Combining Phollow with optically transparent zebrafish enabled us to directly visualize phage outbreaks within the vertebrate gut. We observed that virions can be rapidly taken up by intestinal tissues, including by enteroendocrine cells, and quickly disseminate to extraintestinal sites, including the liver and brain. Moreover, antibiotics trigger waves of interbacterial transmission leading to sudden shifts in spatial organization and composition of defined gut communities. Phollow ultimately empowers multiscale investigations connecting phage transmission to transkingdom interactions that have the potential to open new avenues for viral-based microbiome therapies.
RESUMEN
The main objective of this rapid systematic review was to examine how the COVID-19 pandemic impacted peer relationships for adolescents (10-25 years of age) around the globe. We focused on four indices of peer relationships: (1) loneliness, (2) social connectedness, (3) social support, and (4) social media use. In addition, we examined gender and age differences. Four databases (APA PsychInfo, PubMed, Scopus, and Web of Science) were searched for articles published from January 2020 to November 2022. A total of 96 studies (cross-sectional: n = 66, longitudinal: n = 30, quantitative: n = 67, qualitative: n = 12, mixed-methods: n = 17) met our inclusion criteria (empirical observational studies with data on at least one of the indices of interest, cross-sectional data on COVID-19-related experiences or longitudinal data collected during the pandemic, age range of 10-25 years, typically developing adolescents). We extracted data and conducted a narrative synthesis. Findings suggest that COVID-19 disruptions negatively impacted peer relationships for youth. Most studies reported either an increase in loneliness over the course of the pandemic or a positive association between loneliness and COVID-19-related experiences. Similar findings were observed for increased social media use as a means of continued communication and connection. Fewer studies focused on social support but those that did reported a decrease or negative association with COVID-19-related experiences. Lastly, findings suggest a mixed impact on social connectedness, which might be due to the strengthening of closer ties and weakening of more distant relationships. Results for gender differences were mixed, and a systematic comparison of differences across ages was not possible. The heterogeneity in measures of COVID-19-related experiences as well as timing of data collection prevented a more nuanced examination of short and more long-term impacts.
RESUMEN
We investigate the effect of bacteriophage infection and antibiotic treatment on the coordination of swarming, a collective form of flagellum- and pilus-mediated motility in bacteria. We show that phage infection of the opportunistic bacterial pathogen Pseudomonas aeruginosa abolishes swarming motility in the infected subpopulation and induces the release of the Pseudomonas quinolone signaling molecule PQS, which repulses uninfected subpopulations from approaching the infected area. These mechanisms have the overall effect of limiting the infection to a subpopulation, which promotes the survival of the overall population. Antibiotic treatment of P. aeruginosa elicits the same response, abolishing swarming motility and repulsing approaching swarms away from the antibiotic-treated area through a PQS-dependent mechanism. Swarms are entirely repelled from the zone of antibiotic-treated P. aeruginosa, consistent with a form of antibiotic evasion, and are not repelled by antibiotics alone. PQS has multiple functions, including serving as a quorum-sensing molecule, activating an oxidative stress response, and regulating the release of virulence and host-modifying factors. We show that PQS serves additionally as a stress warning signal that causes the greater population to physically avoid cell stress. The stress response at the collective level observed here in P. aeruginosa is consistent with a mechanism that promotes the survival of bacterial populations.IMPORTANCE We uncover a phage- and antibiotic-induced stress response in the clinically important opportunistic pathogen Pseudomonas aeruginosa Phage-infected P. aeruginosa subpopulations are isolated from uninfected subpopulations by the production of a stress-induced signal. Activation of the stress response by antibiotics causes P. aeruginosa to physically be repelled from the area containing antibiotics altogether, consistent with a mechanism of antibiotic evasion. The stress response observed here could increase P. aeruginosa resilience against antibiotic treatment and phage therapy in health care settings, as well as provide a simple evolutionary strategy to avoid areas containing stress.
