Modeling the growth of Salmonella in raw ground pork under dynamic conditions of temperature abuse.

Salmonella contamination of pork products is a significant public health concern. Temperature abuse scenarios, such as inadequate refrigeration or prolonged exposure to room temperature, can enhance Salmonella proliferation. This study aimed to develop and validate models for Salmonella growth considering competition with background microbiota in raw ground pork, under isothermal and dynamic conditions of temperature abuse between 10 and 40 °C. The maximum specific growth rate (µmax) and maximum population density (MPD) were estimated to quantitatively describe the growth behavior of Salmonella. To reflect more realistic microbial interactions in Salmonella-contaminated product, our model considered competition with the background microbiota, measured as mesophilic aerobic plate counts (APC). Notably, the µmax of Salmonella in low-fat samples (∼5 %) was significantly higher (p < 0.05) than that in high-fat samples (∼25 %) at 10, 20, and 30 °C. The average doubling time of Salmonella was 26, 4, 2, 1.5, 0.8, and 1.1 h at 10, 15, 20, 25, 30, and 40 °C, respectively. The initial concentration of Salmonella minimally impacted its growth in ground pork at any temperature. The MPD of APC consistently exceeded that of Salmonella, indicating the growth of APC without competition from Salmonella. The competition model exhibited excellent fit with the experimental data, as 95 % (627/660) of residual errors fell within the desired acceptable prediction zone (pAPZ >0.70). The theoretical minimum and optimum growth temperatures for Salmonella ranged from 5 to 6 °C and 35 to 36 °C, respectively. The dynamic model displayed strong predictive performance, with 90 % (57/63) of residual errors falling within the APZ. Dynamic models could be valuable tools for validating and refining simpler static or isothermal models, ultimately improving their predictive capabilities to enhance food safety.

Intraspecific variation in Janzen-Connell effect is mediated by stress and plant-soil feedbacks.

Janzen-Connell (JC) effects, hypothesized to be partially driven by negative plant-soil feedbacks (PSFs), are considered to be a key mechanism that regulates tropical forest plant diversity and coexistence. However, intraspecific variation in JC effects may weaken this mechanism, with the strength of PSFs being a potentially key variable process. We conducted a manipulated experiment with seedlings from two populations of Pometia pinnata (Sapindaceae), a tropical tree species in southwest China. We aimed to measure the intraspecific difference in PSF magnitude caused by inoculating the soil from different P. pinnata source populations and growing seedlings under differing light intensity and water availability treatments, and at varying plant densities. We found negative PSFs for both populations with the inoculum soil originating from the same sites, but PSFs differed significantly with the inoculum soil from different sites. PSF strength responded differently to biotic and abiotic drivers; PSF strength was weaker in low moisture and high light treatments than in high moisture and low light treatments. Our study documents intraspecific variation in JC effects: specifically, P. pinnata have less defenses to their natively-sourced soil, but are more defensive to the soil feedbacks from soil sourced from other populations. Our results imply that drought and light intensity tended to weaken JC effects, which may result in loss of species diversity with climate change.

Predicting the response of a long-distance migrant to changing environmental conditions in winter.

Access to high-quality food is critical for long-distance migrants to provide energy for migration and arrival at breeding grounds in good condition. We studied effects of changing abundance and availability of a marine food, common eelgrass (Zostera marina L.), on an arctic-breeding, migratory goose, black brant (Brant bernicla nigricans Lawrence 1846), at a key non-breeding site, Bahía San Quintín, Mexico. Eelgrass, the primary food of brant, is consumed when exposed by the tide or within reach from the water's surface. Using an individual-based model, we predicted effects of observed changes (1991-2013) in parameters influencing food abundance and availability: eelgrass biomass (abundance), eelgrass shoot length (availability, as longer shoots more within reach), brant population size (availability, as competition greater with more birds), and sea level (availability, as less food within reach when sea level higher). The model predicted that the ability to gain enough energy to migrate was most strongly influenced by eelgrass biomass (threshold January biomass for migration = 60 g m-2 dry mass). Conversely, annual variation in population size (except for 1998), was relatively low, and variation in eelgrass shoot length and sea level were not strongly related to ability to migrate. We used observed data on brant body mass at Bahía San Quintín and annual survival to test for effects of eelgrass biomass in the real system. The lowest observed values of body mass and survival were in years when biomass was below 60 g m-2, although in some years of low biomass body mass and/or survival was higher. This suggests that the real birds may have some capacity to compensate to meet their energy demands when eelgrass biomass is low. We discuss consequences for brant population trends and conservation.

Analyzing soccer match sprint distances: A comparison of GPS-based absolute and relative thresholds.

This study compared the most common absolute sprint threshold (> 25.2 km/h) with relative and individualized thresholds (> 70%, > 75%, > 80%, > 85% and > 90% of peak match speed). Twenty elite soccer players, competing in the first division of the Portuguese League, were monitored using GNSS equipment during thirty-four official matches. Peak match speed was retrieved as the individual maximal speed reached during the full season. Distances were registered when speed overcame the absolute and the relative thresholds. Mean ± SD of peak speeds and distances covered were calculated, and Pearson correlation (r) and mean paired differences were performed to analyze relationships and differences between thresholds. The peak match speed was 32.9 ± 1.4 km/h. Correlations between distances covered using the absolute and relative thresholds varied from very strong (> 70%: r = 0.84, p < .001; > 75%: r = 0.89, p < .001; and > 80%: r = 0.88, p < .001), strong (> 85%: r = 0.79, p < .001), to moderate (> 90%: r = 0.59, p < .001). Overall, the > 75% (ES: 0.23 [95% CI: 0.16, 0.31]) and the > 90% (ES: -1.65 [95%CI: -1.85, -1.48]) relative thresholds presented the smallest and largest differences, respectively, with the absolute threshold. Differences were also found when considering the playing positions. While the distances covered by central midfielders were similar between the absolute and > 80% thresholds (-0.03 [-0.16, 0.10]), fullbacks covered largely more distance -1.88 [-2.42 -1.50]) in the absolute threshold than in the > 80% threshold. The distances covered by players varied based on the selected threshold, affecting the distances covered by different playing positions. Being the highest speed threshold within displacements thresholds, the absolute sprint threshold showed greater similarity to lower rather than higher relative thresholds.

Coordination, cooperation, competition, crowding and congestion of molecular motors: Theoretical models and computer simulations.

Cytoskeletal motor proteins are biological nanomachines that convert chemical energy into mechanical work to carry out various functions such as cell division, cell motility, cargo transport, muscle contraction, beating of cilia and flagella, and ciliogenesis. Most of these processes are driven by the collective operation of several motors in the crowded viscous intracellular environment. Imaging and manipulation of the motors with powerful experimental probes have been complemented by mathematical analysis and computer simulations of the corresponding theoretical models. In this article, we illustrate some of the key theoretical approaches used to understand how coordination, cooperation and competition of multiple motors in the crowded intra-cellular environment drive the processes that are essential for biological function of a cell. In spite of the focus on theory, experimentalists will also find this article as an useful summary of the progress made so far in understanding multiple motor systems.

Competitive inhibition and mutualistic growth in co-infections: deciphering Staphylococcus aureus-Acinetobacter baumannii interaction dynamics.

Staphylococcus aureus (Sa) and Acinetobacter baumannii (Ab) are frequently co-isolated from polymicrobial infections that are severe and refractory to therapy. Here, we apply a combination of wet-lab experiments and in silico modeling to unveil the intricate nature of the Ab/Sa interaction using both, representative laboratory strains and strains co-isolated from clinical samples. This comprehensive methodology allowed uncovering Sa's capability to exert a partial interference on Ab by the expression of phenol-soluble modulins. In addition, we observed a cross-feeding mechanism by which Sa supports the growth of Ab by providing acetoin as an alternative carbon source. This study is the first to dissect the Ab/Sa interaction dynamics wherein competitive and cooperative strategies can intertwine. Through our findings, we illuminate the ecological mechanisms supporting their coexistence in the context of polymicrobial infections. Our research not only enriches our understanding but also opens doors to potential therapeutic avenues in managing these challenging infections.

Competitive protein adsorption in isocratic anion exchange chromatography.

Protein chromatography is the dominant method of purification of biopharmaceuticals. Although all practical chromatography involves competitive absorption and separation of M. species, competitive protein absorption has remained inadequately understood. We previously introduced the measurement of equilibrium protein adsorption isotherms with all intensive variables held constant, including competitor concentration. In this work, we introduce isocratic chromatographic retention measurements of dynamic protein adsorption in the presence of a constant concentration of a competitor protein. These measurements are achieved by establishing a dynamic equilibrium with a constant concentration of competitor (insulin) in the mobile phase flowing through an ion exchange adsorbent column and following the behavior of a test protein (α-lactalbumin) injected into this environment. We observed decreased retention times for α-lactalbumin in presence of the competitor. The presence of competitor also reduces the heterogeneity of the sites available for adsorption of the test protein. This investigation provides an approach to fundamental understanding of competitive dynamics of multicomponent protein chromatography.

Positive and negative plant-plant interactions influence seedling establishment at both high and low elevations.

Deciphering how plants interact with each other across environmental gradients is important to understand plant community assembly, as well as potential future plant responses to environmental change. Plant-plant interactions are expected to shift from predominantly negative (i.e. competition) to predominantly positive (i.e. facilitation) along gradients of environmental severity. However, most experiments examine the net effects of interactions by growing plants in either the presence or absence of neighbours, thereby neglecting the interplay of both negative and positive effects acting simultaneously within communities. To partially unravel these effects, we tested how the seedling establishment of 10 mountain grassland plants varied in the presence versus absence of plant communities at two sites along an elevation gradient. We created a third experimental treatment (using plastic plant mats to mimic surrounding vegetation) that retained the main hypothesised benefits of plant neighbours (microsite amelioration), while reducing a key negative effect (competition for soil resources). In contrast to our expectations, we found evidence for net positive effects of vegetation at the low elevation site, and net negative effects at the high elevation site. Interestingly, the negative effects of plant neighbours at high elevation were driven by high establishment rates of low elevation grasses in bare soil plots. At both sites, establishment rates were highest in artificial vegetation (after excluding two low elevation grasses at the high elevation site), indicating that positive effects of above-ground vegetation are partially offset by their negative effects. Our results demonstrate that both competition and facilitation act jointly to affect community structure across environmental gradients, while emphasising that competition can be strong also at higher elevations in temperate mountain regions. Consequently, plant-plant interactions are likely to influence the establishment of new, and persistence of resident, species in mountain plant communities as environments change. Supplementary Information: The online version contains supplementary material available at 10.1007/s00035-023-00302-8.

Mechanisms of biodiversity loss under nitrogen enrichment: unveiling a shift from light competition to cation toxicity.

The primary mechanisms contributing to nitrogen (N) addition induced grassland biodiversity loss, namely light competition and soil cation toxicity, are often examined separately in various studies. However, their relative significance in governing biodiversity loss along N addition gradient remains unclear. We conducted a 4-yr field experiment with five N addition rates (0, 2, 10, 20, and 50 g N m-2 yr-1) and performed a meta-analysis using global data from 239 observations in N-fertilized grassland ecosystems. Results from our field experiment and meta-analysis indicate that both light competition and soil cation (e.g. Mn2+ and Al3+) toxicity contribute to plant diversity loss under N enrichment. The relative importance of these mechanisms varied with N enrichment intensity. Light competition played a more significant role in influencing species richness under low N addition (≤ 10 g m-2 yr-1), while cation toxicity became increasingly dominant in reducing biodiversity under high N addition (>10 g m-2 yr-1). Therefore, a transition from light competition to cation toxicity occurs with increasing N availability. These findings imply that the biodiversity loss along the N gradient is regulated by distinct mechanisms, necessitating the adoption of differential management strategies to mitigate diversity loss under varying intensities of N enrichment.

Unexpected increase of sulfate concentrations and potential impact on CH4 budgets in freshwater lakes.

The continuous increase in sulfate (SO42-) concentrations discharged by anthropogenic activities lacks insights into their dynamics and potential impact on CH4 budgets in freshwater lakes. Here we conducted a field investigation in the lakes along the highly developed Yangtze River basin, China, additionally, we analyzed long-term data (1950-2020) from Lake Taihu, a typical eutrophic lake worldwide. We observed a gradual increase in SO42- concentrations up to 100 mg/L, which showed a positive correlation with the trophic state of the lakes. The annual variations indicated that eutrophication intensified the fluctuation of SO42- concentrations. A random forest model was applied to assess the impact of SO42- concentrations on CH4 emissions, revealing a significant negative effect. Synchronously, a series of microcosms with added SO42- were established to simulate cyanobacteria decomposition processes and explore the coupling mechanism between sulfate reduction and CH4 production. The results showed a strong negative correlation between CH4 concentrations and initial SO42- levels (R2 = 0.83), indicating that higher initial SO42- concentrations led to lower final CH4 concentrations. This was attributed to the competition for cyanobacteria-supplied substrates between sulfate reduction bacteria (SRB) and methane production archaea (MPA). Our study highlights the importance of considering the unexpectedly increasing SO42- concentrations in eutrophic lakes when estimating global CH4 emission budgets.

Synthesis of sexual selection: a systematic map of meta-analyses with bibliometric analysis.

Sexual selection has been a popular subject within evolutionary biology because of its central role in explaining odd and counterintuitive traits observed in nature. Consequently, the literature associated with this field of study became vast. Meta-analytical studies attempting to draw inferences from this literature have now accumulated, varying in scope and quality, thus calling for a synthesis of these syntheses. We conducted a systematic literature search to create a systematic map with a report appraisal of meta-analyses on topics associated with sexual selection, aiming to identify the conceptual and methodological gaps in this secondary literature. We also conducted bibliometric analyses to explore whether these gaps are associated with the gender and origin of the authors of these meta-analyses. We included 152 meta-analytical studies in our systematic map. We found that most meta-analyses focused on males and on certain animal groups (e.g. birds), indicating severe sex and taxonomic biases. The topics in these studies varied greatly, from proximate (e.g. relationship of ornaments with other traits) to ultimate questions (e.g. formal estimates of sexual selection strength), although the former were more common. We also observed several common methodological issues in these studies, such as lack of detailed information regarding searches, screening, and analyses, which ultimately impairs the reliability of many of these meta-analyses. In addition, most of the meta-analyses' authors were men affiliated to institutions from developed countries, pointing to both gender and geographical authorship biases. Most importantly, we found that certain authorship aspects were associated with conceptual and methodological issues in meta-analytical studies. Many of our findings might simply reflect patterns in the current state of the primary literature and academia, suggesting that our study can serve as an indicator of issues within the field of sexual selection at large. Based on our findings, we provide both conceptual and analytical recommendations to improve future studies in the field of sexual selection.

Competition and drought affect cleistogamy in a non-additive way in the annual ruderal Lamium amplexicaule.

Competition affects mixed-mating strategies by limiting available abiotic or biotic resources such as nutrients, water, space, or pollinators. Cleistogamous species produce closed (cleistogamous, CL), obligately selfed, simultaneously with open (chasmogamous, CH), potentially outcrossed flowers. The effects of intraspecific competition on fitness and cleistogamy variation can range from limiting the production of costly CH flowers because of resource limitation, to favouring CH production because of fitness advantages of outcrossed, CH offspring. Moreover, the effects of competition can be altered when it co-occurs with other environmental variations. We grew plants from seven populations of the ruderal Lamium amplexicaule, originating from different climates and habitats, in a common garden experiment combining drought, interspecific competition, and seasonal variation. All these parameters have been shown to influence the degree of cleistogamy in the species on their own. In spring, competition and drought negatively impacted fitness, but the CL proportion only increased when plants were exposed to both treatments combined. We did not observe the same results in autumn, which can be due to non-adaptive phenotypic variation, or to differences in soil compactness between seasons. The observed responses are largely due to phenotypic plasticity, but we also observed phenotypic differentiation between populations for morphological, phenological, and cleistogamy traits, pointing to the existence of different ecotypes. Our data do not support the hypothesis that CL proportion should decrease when resources are scarce, as plants with reduced growth had relatively low CL proportions. We propose that variation in cleistogamy could be an adaptation to pollinator abundance, or to environment-dependent fitness differences between offspring of selfed and outcrossed seeds, two hypotheses worth further investigation. This opens exciting new possibilities for the study of the maintenance of mixed-mating systems using cleistogamous species as models that combine the effects of inbreeding and reproductive costs.

An orphan gene enhances male reproductive success in Plutella xylostella.

Plutella xylostella exhibits exceptional reproduction ability, yet the genetic basis underlying the high reproductive capacity remains unknown. Here, we demonstrate that an orphan gene, lushu, which encodes a sperm protein, plays a crucial role in male reproductive success. Lushu is located on the Z chromosome and is prevalent across different P. xylostella populations worldwide. We subsequently generated lushu mutants using transgenic CRISPR/Cas9 system. Knockout of Lushu results in reduced male mating efficiency and accelerated death in adult males. Furthermore, our findings highlight that the deficiency of lushu reduced the transfer of sperms from males to females, potentially resulting in hindered sperm competition. Additionally, the knockout of Lushu results in disrupted gene expression in energy-related pathways and elevated insulin levels in adult males. Our findings reveal that male reproductive performance has evolved through the birth of a newly evolved, lineage-specific gene with enormous potentiality in fecundity success. These insights hold valuable implications for identifying the target for genetic control, particularly in relation to species-specific traits that are pivotal in determining high levels of fecundity.

Should the use of omeprazole be allowed during equestrian competition?

BACKGROUND: Prioritising equine welfare, making evidenced-based policy, and consistent decision-making across sports are crucial to maintaining the social licence for equestrian sport. Regulations on the use of omeprazole during competition differ; all regulators argue that their rules prioritise welfare. This discrepancy is a matter of concern to the public and equestrian stakeholders. OBJECTIVES: To apply Campbell's Ethical Framework for the use of Horses in Sport to the question: 'Should the use of omeprazole be allowed during equestrian competition?' STUDY DESIGN: A desk-based ethico-legal study. METHODS: Campbell's Ethical Framework for the Use of Horses in Sport was applied in a stepwise fashion: definition of the ethical question; analysis of the evidence base; consideration of stakeholders' interests; harm:benefit analysis; application of the three central tenets of the framework, and formulation of conclusions and recommendations. RESULTS: Stakeholders in equine sports have a variety of (frequently conflicting) interests; all of them share an interest in optimising equine welfare. The incidence of EGUS in competition horses is high. Omeprazole is a cornerstone treatment. There are currently discrepancies in regulation about the use of omeprazole during competitions. Recent evidence suggests that withholding omeprazole treatment for two clear days before competition allows the recurrence of squamous EGUS, whereas withholding treatment on the day of competition only does not have that effect. MAIN LIMITATIONS: The current state of scientific knowledge about the use of omeprazole in horses. The analysis did not consider possible health and thus welfare effects of the out-of-competition treatment with omeprazole. CONCLUSIONS: Based on recent scientific evidence, if horses are being treated with omeprazole outside of competition then treatment on the day of competition should be permitted on welfare grounds. Revision of regulations around the use of omeprazole during competition by governing bodies is necessary to safeguard the ethical use of horses in sport.

CONTEXTO: Priorizar o bem­estar equino, elaborar políticas baseadas em evidências e tomar decisões consistentes em todos os esportes são cruciais para manter a licença social para o esporte equestre. As regulamentações sobre o uso de omeprazol durante a competição diferem; todos os reguladores argumentam que suas regras priorizam o bem­estar. Essa discrepância é motivo de preocupação para o público. OBJETIVOS: Aplicar o Modelo Ético de Campbell para o Uso de Cavalos em Esportes1 à pergunta: 'Deve o uso de omeprazol ser permitido durante a competição equestre?' DESENHO DO ESTUDO: Um estudo ético­legal baseado em pesquisa documental. METODOLOGIA: O Modelo Ético de Campbell para o Uso de Cavalos em Esportes1 foi aplicado de forma gradual: definição da questão ética; análise da base de evidências; consideração dos interesses do público alvo; uma análise de dano:benefício; aplicação dos três princípios centrais do modelo; e formulação de conclusões e recomendações. RESULTADOS: O público de esporte equino têm uma variedade de interesses (frequentemente conflitantes), enquanto todos compartilham o interesse em otimizar o bem­estar equino. A incidência de EGUS (Síndrome da Úlcera Gástrica Equina) em cavalos de competição é alta, a qual o omeprazol é um tratamento fundamental. Atualmente, há discrepâncias na regulamentação sobre o uso de omeprazol durante competições. Evidências recentes sugerem que a suspensão do tratamento com omeprazol por 2 dias antes da competição permite a recorrência da EGUS da porção escamosa, enquanto a suspensão do tratamento apenas no dia da competição não tem esse efeito. PRINCIPAIS LIMITAÇÕES: O estado atual do conhecimento científico sobre o uso de omeprazol em cavalos. A análise não considerou possíveis efeitos sobre a saúde e, portanto, sobre o bem­estar do tratamento com omeprazol fora da competição. CONCLUSÕES: Com base em evidências científicas recentes, se os cavalos estão sendo tratados com omeprazol fora da competição, o tratamento no dia da competição deve ser permitido por razões de bem­estar. A revisão das regulamentações sobre o uso de omeprazol durante a competição pelos órgãos reguladores é necessária para salvaguardar o uso ético dos cavalos no esporte.

The Drosophila TNF Eiger promotes Myc super-competition independent of canonical JNK signaling.

Numerous factors have been implicated in the cell-cell interactions that lead to elimination of cells via cell competition, a context-dependent process of cell selection in somatic tissues that is based on comparisons of cellular fitness. Here we use a series of genetic tests in Drosophila to explore the relative contribution of the pleiotropic cytokine Tumor Necrosis Factor ⍺ (TNF⍺) in Myc-mediated cell competition (also known as Myc super-competition or Myc cell competition). We find that the sole Drosophila TNF, Eiger (Egr), its receptor Grindelwald (Grnd/TNFR), and the adaptor proteins Traf4 and Traf6 are required to eliminate wild-type "loser" cells during Myc cell competition. Although typically the interaction between Egr and Grnd leads to cell death by activating the intracellular Jun N-terminal Kinase (JNK) stress signaling pathway, our experiments reveal that many components of canonical JNK signaling are dispensable for cell death in Myc cell competition, including the JNKKK Tak1, the JNKK Hemipterous (Hep) and the JNK Basket (Bsk). Our results suggest that Egr/Grnd signaling participates in Myc cell competition, but functions in a role that is largely independent of the JNK signaling pathway.

Nasal commensals reduce Staphylococcus aureus proliferation by restricting siderophore availability.

The human microbiome is critically associated with human health and disease. One aspect of this is that antibiotic-resistant opportunistic bacterial pathogens such as methicillin-resistant Staphylococcus aureus can reside within the nasal microbiota which increases the risk of infections. Epidemiological studies of the nasal microbiome have revealed positive and negative correlations between non-pathogenic species and S. aureus, but the underlying molecular mechanisms remain poorly understood. The nasal cavity is iron-limited and bacteria are known to produce iron-scavenging siderophores to proliferate in such environments. Siderophores are public goods that can be consumed by all members of a bacterial community. Accordingly, siderophores are known to mediate bacterial competition and collaboration but their role in the nasal microbiome is unknown. Here we show that siderophore acquisition is crucial for S. aureus nasal colonization in vivo. We screened 94 nasal bacterial strains from seven genera for their capacity to produce siderophores as well as to consume the siderophores produced by S. aureus. We found that 80% of the strains engaged in siderophore mediated interactions with S. aureus. Non-pathogenic corynebacterial species were found to be prominent consumers of S. aureus siderophores. In co-culture experiments, consumption of siderophores by competitors reduced S. aureus growth in an iron dependent fashion. Our data show a wide network of siderophore mediated interactions between the species of the human nasal microbiome and provide mechanistic evidence for inter-species competition and collaboration impacting pathogen proliferation. This opens avenues for designing nasal probiotics to displace S. aureus from the nasal cavity of humans.

Intimate relationships regulate female brain activity in a competitive context: evidence from EEG and functional connectivity analysis.

Competition is common in life, and intimate relationships are essential. Understanding how intimate relationships impact an individual's competitive process is crucial. This study explored the impact of competitor gender on female competition using electroencephalography analysis. The results revealed that females exhibited a smaller median of the absolute value of reaction time difference (DRT) between their partners and their competitors when their partners were absent compared to when their partners were present. Additionally, females showed greater average amplitudes of N2 posterior contralateral component (N2pc) and Late Positive Potential (LPP), increased activation of the alpha frequency band, and enhanced theta frequency band functional connectivity between the central parietal lobe and occipital lobe. Furthermore, when competing with individuals of the same gender as opposed to individuals of the opposite gender, females exhibited greater average amplitudes of percentage of wins and N2pc. A significant negative correlation was noted between the DRT and the average wave amplitudes of N2pc and LPP. These findings suggest that females are more engaged in competitive tasks when partners are not present and have improved decision-making when competing with same-gender individuals. This study provides evidence for the influence of lovers on female competition, helping females adapt to social competition and promoting healthy relationships.

Initiation of H1-T6SS dueling between Pseudomonas aeruginosa.

The Type VI secretion system (T6SS) is a multicomponent apparatus, present in many Gram-negative bacteria, which can inhibit bacterial prey in various ecological niches. Pseudomonas aeruginosa assembles one of its three T6SS (H1-T6SS) to respond to attacks from adjacent competing bacteria. Surprisingly, repeated assemblies of the H1-T6SS, termed dueling, were described in a monoculture in the absence of an attacker strain; however, the underlying mechanism was unknown. Here, we explored the role of H2-T6SS of P. aeruginosa in triggering H1-T6SS assembly. We show that H2-T6SS inactivation in P. aeruginosa causes a significant reduction in H1-T6SS dueling and that H2-T6SS activity directly triggers retaliation by the H1-T6SS. Intraspecific competition experiments revealed that elimination of H2-T6SS in non-immune prey cells conferred protection from H1-T6SS. Moreover, we show that the H1-T6SS response is triggered independently of the characterized lipase effectors of the H2-T6SS, as well as those of Acinetobacter baylyi and Vibrio cholerae. Our results suggest that H1-T6SS response to H2-T6SS in P. aeruginosa can impact intraspecific competition, particularly when the H1-T6SS effector-immunity pairs differ between strains, and could determine the outcome of multistrain colonization.IMPORTANCEThe opportunistic pathogen Pseudomonas aeruginosa harbors three different Type VI secretion systems (H1, H2, and H3-T6SS), which can translocate toxins that can inhibit bacterial competitors or inflict damage to eukaryotic host cells. Unlike the unregulated T6SS assembly in other Gram-negative bacteria, the H1-T6SS in P. aeruginosa is precisely assembled as a response to various cell damaging attacks from neighboring bacterial cells. Surprisingly, it was observed that neighboring P. aeruginosa cells repeatedly assemble their H1-T6SS toward each other. Mechanisms triggering this "dueling" behavior between sister cells were unknown. In this report, we used a combination of microscopy, genetic and intraspecific competition experiments to show that H2-T6SS initiates H1-T6SS dueling. Our study highlights the interplay between different T6SS clusters in P. aeruginosa, which may influence the outcomes of multistrain competition in various ecological settings such as biofilm formation and colonization of cystic fibrosis lungs.

Multivariate pattern analysis of cooperation and competition in constructive action.

The neural underpinning of cooperative and competitive constructive activity has been investigated using mass-univariate approaches. In this study, we sought to compare the results of these approaches with the results of multivariate pattern analysis (MVPA). In particular, we wanted to test whether MVPA supports the claim made in previous studies that cooperation is associated with the activity of reward-related brain circuits. Participants were required to construct a pattern on the screen either individually or in cooperation or competition with another person during an fMRI scan. Both the MVPA classification methods and the representational similarity analysis indicated the involvement of orbitofrontal and ventromedial prefrontal areas in processes that distinguish between cooperation and competition, and activation analysis showed that these areas are more active during cooperation than during competition. However, a single trial analysis showed that the effect was reversed when only winning trials were considered. In these trials, activation of reward-related areas was higher during competition than during cooperation. Moreover, the contrast between won and lost trials in terms of reward circuits involvement was sharper under competition than under cooperation. Thus, although cooperation can be generally more rewarding than competition, it is associated with smaller difference between trials lost and trials won in terms of reward circuits activation. One may speculate that in cooperation, victory and defeat are shared with the partner and, contrary to competition, are not experienced as personal achievement or failure.

Competitive (but not cooperative) body odors bias the discrimination of action intentions towards cooperation.

Odors help us to interpret the environment, including the nature of social interactions. But, whether and how they influence the ability to discriminate the intentional states embedded in actions is unclear. In two experiments, we asked two independent groups of participants to discriminate motor intentions from videos showing one agent performing a reach-to-grasp movement with another agent with a cooperative or a competitive intent, and the same movement performed alone at either natural- or fast-speed, as controls. Task-irrelevant odor primes preceded each video presentation. Experiment 1 (N = 19) included masked cooperative and competitive body odors (human sweat collected while the donors were engaged in cooperative and competitive activities), whereas Experiment 2 (N = 20) included a common odor (cedarwood oil) and no odor (clean air) as primes. In an odor-primed, two-alternative forced choice task, participants discriminated the intention underlying the observed action. The results indicated that the odor exposure modulated the discrimination speed across different intentions, but only when the action intentions were hard to discriminate (cooperative vs. individual natural-speed, and competitive vs. individual fast-speed). Contrary to our hypothesis, a direct odor-action intention compatibility effect was not found. Instead, we propose a negative arousal compatibility-like effect to explain our results. Discrimination of high arousing action intentions (i.e., competitive) took longer when primed by high arousing odors (common odor and competitive body odor) than by low arousing odors (cooperative body odor and no odor). Discrimination of low arousing action intentions (i.e., cooperative) took longer when primed by low arousing odors than by high arousing odors. All in all, competitive (but not cooperative) body odors bias the discrimination of action intentions towards cooperation.