Nonkin interactions between Bacillus subtilis soil isolates limit the spread of swarming deficient cheats.

Cooperative behaviours in human, animal, and even microbial societies are vulnerable to exploitation. Kin discrimination has been hypothesized to help stabilize cooperation. However, the mechanisms that sustain cooperative behaviour remain poorly understood. Here, we investigate the role of kin discrimination in limiting the spread of cheats in adjoining populations during surfactant-dependent cooperative swarming over surfaces using the bacterium Bacillus subtilis as a model organism. We show that mixing surfactant secreting cooperators and cheats that do not produce surfactants at 1:1 initial ratio quickly leads to cooperation collapse. However, when such common swarms encounter nonkin B. subtilis swarms, the proportion of the surfactant nonproducers decreases, suggesting that kinship dependent interactions may limit cheats' advantage in an adjoining population. To further validate this finding, we subjected wild-type cooperators to multiple transient encounters with kin and nonkin swarms over 20 cycles of experimental evolution. The evolved populations exposed to nonkin swarms less frequently contained defective swarming phenotypes compared to those encountering kin swarms. Altogether, our results support the prediction that the spread of cheats in an adjoining bacterial population is impeded by kin discrimination interactions, which might have a role in stabilizing cooperative behaviour in evolving populations.

Molecular correlates of swarming behaviour in Aedes aegypti males.

Mosquitoes are the deadliest vectors of diseases. They impose a huge health burden on human populations spreading parasites as disparate as protozoans (malaria), viruses (yellow fever and more) and nematodes (filariasis) that cause life-threatening conditions. In recent years, mating has been proposed as a putative target for population control. Mosquitoes mate mid-air, in swarms initiated by males and triggered by a combination of internal and external stimuli. As the number of females in a swarm is limited, there is intense competition among males, and they 'retune' their physiology for this demanding behaviour. There is limited knowledge on the 'genetic reprogramming' required to enable swarming. Interestingly, recent evidence indicates that the upregulation of circadian clock genes may be involved in the swarming of malaria mosquitoes of the genus Anopheles. Here, we use whole-head RNA-seq to identify gene expression changes in Aedes aegypti males that are engaged in swarming in a laboratory setting. Our results suggest that in preparation to swarming, males tend to lower some housekeeping functions while increasing remodelling of the cytoskeleton and neuronal connectivity; the transcription of circadian clock genes is unaffected.

Spatial correlations in laboratory insect swarms.

In contrast with flocks of birds, schools of fish and herds of animals, swarms of the non-biting midge Chironomus riparius do not possess global order and under quiescent conditions velocities are only weakly correlated at long distances. Without such order it is challenging to characterize the collective behaviours of the swarms which until now have only been evident in their coordinated responses to disturbances. Here I show that the positions of the midges in laboratory swarms are maximally anticorrelated. This novel form of long-range ordering has until now gone unnoticed in the literature on collective animal movements. Here, its occurrence is attributed to midges being, in nearly equal measure, attracted towards the centre of the swarm and repelled by one another. It is shown that the midge swarms are poised at the cusp of a stable-unstable phase transition.

Enhanced antifouling and anti-swarming properties poly (sulfobetaine methacrylate-co-2-hydroxy-3-phenoxypropyl acrylate) hydrogel coatings for urinary catheters.

Catheter-associated urinary tract infection (CAUTI) remains an unsolved challenge to date, particularly with the emergence and rapid spread of antimicrobial-resistant bacterial pathogens. Despite extensive research, a catheter coating that can offer intrinsic resistance to host protein deposition, bacterial biofilm formation, and swarming is still urgently required. Zwitterionic hydrogel coatings due to their superior lubricity and antifouling properties represent a promising candidate, but their weak mechanical stability in water and poor resistance to bacterial swarming migration limit their application in urinary catheters for infection control. In this research, we describe the fabrication of a multifunctional catheter coating by copolymerizing zwitterionic sulfobetaine methacrylate (SBMA) polymers and a swarming inhibitor material, 2-hydroxy-3-phenoxypropyl acrylate (HPA). The introduction of polyHPA (PHPA) effectively impeded the uncontrolled swelling behavior of the zwitterionic PSBMA hydrogel, resulting in enhanced mechanical stability. Moreover, the copolymer coating retains the antifouling and anti-swarming properties of the homopolymers when challenged with fibrinogen, Escherichia coli, and Proteus mirabilis. The HPA content significantly correlated with its anti-adhesion activity against fibrinogen and biofilm, and the coating with an SBMA: HPA monomer feed molar ratio of 4:1 showed the best antifouling activity, reducing fibrinogen deposition by about 40 % and biofilm coverage by around fourfold compared to the uncoated polydimethylsiloxane (PDMS) surface. Furthermore, the copolymer coating also exhibited no cytotoxicity, suggesting it as a promising catheter coating for preventing CAUTI.

Swarms of Enzymatic Nanobots for Efficient Gene Delivery.

This study investigates the synthesis and optimization of nanobots (NBs) loaded with pDNA using the layer-by-layer (LBL) method and explores the impact of their collective motion on the transfection efficiency. NBs consist of biocompatible and biodegradable poly(lactic-co-glycolic acid) (PLGA) nanoparticles and are powered by the urease enzyme, enabling autonomous movement and collective swarming behavior. In vitro experiments were conducted to validate the delivery efficiency of fluorescently labeled NBs, using two-dimensional (2D) and three-dimensional (3D) cell models: murine urothelial carcinoma cell line (MB49) and spheroids from human urothelial bladder cancer cells (RT4). Swarms of pDNA-loaded NBs showed enhancements of 2.2- to 2.6-fold in delivery efficiency and 6.8- to 8.1-fold in material delivered compared to inhibited particles (inhibited enzyme) and the absence of fuel in a 2D cell culture. Additionally, efficient intracellular delivery of pDNA was demonstrated in both cell models by quantifying and visualizing the expression of eGFP. Swarms of NBs exhibited a >5-fold enhancement in transfection efficiency compared to the absence of fuel in a 2D culture, even surpassing the Lipofectamine 3000 commercial transfection agent (cationic lipid-mediated transfection). Swarms also demonstrated up to a 3.2-fold enhancement in the amount of material delivered in 3D spheroids compared to the absence of fuel. The successful transfection of 2D and 3D cell cultures using swarms of LBL PLGA NBs holds great potential for nucleic acid delivery in the context of bladder treatments.

Improving Beneficial Traits in Bacillus cabrialesii subsp. cabrialesii TE3T through UV-Induced Genomic Changes.

It is essential to hunt for new technologies that promote sustainable practices for agroecosystems; thus, the bioprospecting of beneficial microorganisms complementing with mutation induction techniques to improve their genomic, metabolic, and functional traits is a promising strategy for the development of sustainable microbial inoculants. Bacillus cabrialesii subsp. cabrialesii strain TE3T, a previously recognized plant growth-promoting and biological control agent, was subjected to UV mutation induction to improve these agro-biotechnological traits. Dilutions were made which were spread on Petri dishes and placed under a 20 W UV lamp at 10-min intervals for 60 min. After the UV-induced mutation of this strain, 27 bacterial colonies showed morphological differences compared to the wild-type strain; however, only a strain named TE3T-UV25 showed an improvement in 53.6% of the biocontrol against Bipolaris sorokiniana vs. the wild-type strain, by competition of nutrient and space (only detected in the mutant strain), as well as diffusible metabolites. Furthermore, the ability to promote wheat growth was evaluated by carrying out experiments under specific greenhouse conditions, considering un-inoculated, strain TE3T, and strain TE3T-UV25 treatments. Thus, after 120 days, biometric traits in seedlings were quantified and statistical analyses were performed, which showed that strain TE3T-UV25 maintained its ability to promote wheat growth in comparison with the wild-type strain. On the other hand, using bioinformatics tools such as ANI, GGDC, and TYGS, the Overall Genome Relatedness Index (OGRI) and phylogenomic relationship of mutant strain TE3T-UV25 were performed, confirming that it changed its taxonomic affiliation from B. cabrialesii subsp. cabrialesii to Bacillus subtilis. In addition, genome analysis showed that the mutant, wild-type, and B. subtilis strains shared 3654 orthologous genes; however, a higher number of shared genes (3954) was found between the TE3T-UV25 mutant strain and B. subtilis 168, while the mutant strain shared 3703 genes with the wild-type strain. Genome mining was carried out using the AntiSMASH v7.0 web server and showed that mutant and wild-type strains shared six biosynthetic gene clusters associated with biocontrol but additionally, pulcherriminic acid cluster only was detected in the genome of the mutant strain and Rhizocticin A was exclusively detected in the genome of the wild-type strain. Finally, using the PlaBase tool, differences in the number of genes (17) associated with beneficial functions in agroecosystems were detected in the genome of the mutant vs. wild-type strain, such as biofertilization, bioremediation, colonizing plant system, competitive exclusion, phytohormone, plant immune response stimulation, putative functions, stress control, and biocontrol. Thus, the UV-induced mutation was a successful strategy to improve the bioactivity of B. cabrialesii subsp. cabrialesii TE3T related to the agro-biotecnology applications. The obtained mutant strain, B. subtilis TE3T-UV25, is a promising strain to be further studied as an active ingredient for the bioformulation of bacterial inoculants to migrate sustainable agriculture.

Flagellar protein FliL: A many-splendored thing.

FliL is a bacterial flagellar protein demonstrated to associate with, and regulate ion flow through, the stator complex in a diverse array of bacterial species. FliL is also implicated in additional functions such as stabilizing the flagellar rod, modulating rotor bias, sensing the surface, and regulating gene expression. How can one protein do so many things? Its location is paramount to understanding its numerous functions. This review will look at the evidence, attempt to resolve some conflicting findings, and offer new thoughts on FliL.

Mosquitoes integrate visual and acoustic cues to mediate conspecific interactions in swarms.

Male mosquitoes form aerial aggregations, known as swarms, to attract females and maximize their chances of finding a mate. Within these swarms, individuals must be able to recognize potential mates and navigate the social environment to successfully intercept a mating partner. Prior research has almost exclusively focused on the role of acoustic cues in mediating the male mosquito's ability to recognize and pursue females. However, the role of other sensory modalities in this behavior has not been explored. Moreover, how males avoid collisions with one another in the swarm while pursuing females remains poorly understood. In this study, we combined free-flight and tethered-flight simulator experiments to demonstrate that swarming Anopheles coluzzii mosquitoes integrate visual and acoustic information to track conspecifics and avoid collisions. Our tethered experiments revealed that acoustic stimuli gated mosquito steering responses to visual objects simulating nearby mosquitoes, especially in males that exhibited a strong response toward visual objects in the presence of female flight tones. Additionally, we observed that visual cues alone could trigger changes in mosquitoes' wingbeat amplitude and frequency. These findings were corroborated by our free-flight experiments, which revealed that Anopheles coluzzii modulate their thrust-based flight responses to nearby conspecifics in a similar manner to tethered animals, potentially allowing for collision avoidance within swarms. Together, these results demonstrate that both males and females integrate multiple sensory inputs to mediate swarming behavior, and for males, the change in flight kinematics in response to multimodal cues might allow them to simultaneously track females while avoiding collisions.

Swarming caddisflies in the mid-cretaceous.

Swarming, as a special form of mating aggregation, is most noteworthy in insects of the orders Ephemeroptera, Diptera, and Trichoptera. Swarming in extant trichopterans is well understood in terms of sex composition, specific mating behaviors, and functional morphological specializations of adults, but an exploration of the evolution of such aggregative behaviors is hampered by the dearth of available examples from the fossil record as well as the ability to reliably distinguish the few gatherings as the result of swarming relative to other taphonomic or behavioral factors. Herein we describe five new fossil species of caddisflies preserved in mid-Cretaceous amber from Myanmar, all preserved as large aggregations. Monospecific aggregations of these five new species can be positively identified as swarms based on morphological traits of wing shape, as well as the presence of particular forms of sexual dimorphism. Results of a phylogenetic reconstruction of both molecular and morphological data as well as ancestral-trait reconstructions and tip-dating analyses indicate that swarming was likely present in the Triassic as a feature of the trichopteran groundplan. Since most Mesozoic insectivorous predators were diurnal based on morphological evidence, largely nocturnal caddisflies would have been freed from such pressures. The phylogeny also shows a correlation between the rise of nocturnal bat predators from the Paleocene or early Eocene and the repeated loss of swarming from various clades of caddisflies, revealing the potential impact of bat predation on reshaping the behavioral landscape of Trichoptera during the Cenozoic.

Self-extinguishing relay waves enable homeostatic control of human neutrophil swarming.

Neutrophils collectively migrate to sites of injury and infection. How these swarms are coordinated to ensure the proper level of recruitment is unknown. Using an ex vivo model of infection, we show that human neutrophil swarming is organized by multiple pulsatile chemoattractant waves. These waves propagate through active relay in which stimulated neutrophils trigger their neighbors to release additional swarming cues. Unlike canonical active relays, we find these waves to be self-terminating, limiting the spatial range of cell recruitment. We identify an NADPH-oxidase-based negative feedback loop that is needed for this self-terminating behavior. We observe near-constant levels of neutrophil recruitment over a wide range of starting conditions, revealing surprising robustness in the swarming process. This homeostatic control is achieved by larger and more numerous swarming waves at lower cell densities. We link defective wave termination to a broken recruitment homeostat in the context of human chronic granulomatous disease.

ATP and Formyl Peptides Facilitate Chemoattractant Leukotriene-B4 Synthesis and Drive Calcium Fluxes, Which May Contribute to Neutrophil Swarming at Sites of Cell Damage and Pathogens Invasion.

Here, we demonstrate that human neutrophil interaction with the bacterium Salmonella typhimurium fuels leukotriene B4 synthesis induced by the chemoattractant fMLP. In this work, we found that extracellular ATP (eATP), the amount of which increases sharply during tissue damage, can effectively regulate fMLP-induced leukotriene B4 synthesis. The vector of influence strongly depends on the particular stage of sequential stimulation of neutrophils by bacteria and on the stage at which fMLP purinergic signaling occurs. Activation of 5-lipoxygenase (5-LOX), key enzyme of leukotriene biosynthesis, depends on an increase in the cytosolic concentration of Ca2+. We demonstrate that eATP treatment prior to fMLP, by markedly reducing the amplitude of the fMLP-induced Ca2+ transient jump, inhibits leukotriene synthesis. At the same time, when added with or shortly after fMLP, eATP effectively potentiates arachidonic acid metabolism, including by Ca2+ fluxes stimulation. Flufenamic acid, glibenclamide, and calmodulin antagonist R24571, all of which block calcium signaling in different ways, all suppressed 5-LOX product synthesis in our experimental model, indicating the dominance of calcium-mediated mechanisms in eATP regulatory potential. Investigation into the adhesive properties of neutrophils revealed the formation of cell clusters when adding fMLP to neutrophils exposed to the bacterium Salmonella typhimurium. eATP added simultaneously with fMLP supported neutrophil polarization and clustering. A cell-derived chemoattractant such as leukotriene B4 plays a crucial role in the recruitment of additional neutrophils to the foci of tissue damage or pathogen invasion, and eATP, through the dynamics of changes in [Ca2+]i, plays an important decisive role in fMLP-induced leukotrienes synthesis during neutrophil interactions with the bacterium Salmonella typhimurium.

Multisensory integration in Anopheles mosquito swarms: The role of visual and acoustic information in mate tracking and collision avoidance.

Male mosquitoes form aerial aggregations, known as swarms, to attract females and maximize their chances of finding a mate. Within these swarms, individuals must be able to recognize potential mates and navigate the dynamic social environment to successfully intercept a mating partner. Prior research has almost exclusively focused on the role of acoustic cues in mediating the male mosquito's ability to recognize and pursue flying females. However, the role of other sensory modalities in this behavior has not been explored. Moreover, how males avoid collisions with one another in the dense swarm while pursuing females remains poorly understood. In this study, we combined free-flight and tethered flight simulator experiments to demonstrate that swarming Anopheles coluzzii mosquitoes integrate visual and acoustic information to track conspecifics and avoid collisions. Our tethered experiments revealed that acoustic stimuli gated mosquito steering responses to visual objects simulating nearby mosquitoes, especially in males that exhibited attraction to visual objects in the presence of female flight tones. Additionally, we observed that visual cues alone could trigger changes in mosquitoes' wingbeat amplitude and frequency. These findings were corroborated by our free-flight experiments, which revealed that mosquitoes modulate their flight responses to nearby conspecifics in a similar manner to tethered animals, allowing for collision avoidance within swarms. Together, these results demonstrate that both males and females integrate multiple sensory inputs to mediate swarming behavior, and for males, the change in flight kinematics in response to multimodal cues allows them to simultaneously track females while avoiding collisions.

Magnetic Microrobot Swarms with Polymeric Hands Catching Bacteria and Microplastics in Water.

The forefront of micro- and nanorobot research involves the development of smart swimming micromachines emulating the complexity of natural systems, such as the swarming and collective behaviors typically observed in animals and microorganisms, for efficient task execution. This study introduces magnetically controlled microrobots that possess polymeric sequestrant "hands" decorating a magnetic core. Under the influence of external magnetic fields, the functionalized magnetic beads dynamically self-assemble from individual microparticles into well-defined rotating planes of diverse dimensions, allowing modulation of their propulsion speed, and exhibiting a collective motion. These mobile microrobotic swarms can actively capture free-swimming bacteria and dispersed microplastics "on-the-fly", thereby cleaning aquatic environments. Unlike conventional methods, these microrobots can be collected from the complex media and can release the captured contaminants in a second vessel in a controllable manner, that is, using ultrasound, offering a sustainable solution for repeated use in decontamination processes. Additionally, the residual water is subjected to UV irradiation to eliminate any remaining bacteria, providing a comprehensive cleaning solution. In summary, this study shows a swarming microrobot design for water decontamination processes.

Multiple pathways impact the swarming motility of Pseudomonas fluorescens Pf0-1.

Swarming motility in pseudomonads typically requires both a functional flagellum and the production/secretion of a biosurfactant. Published work has shown that the wild-type Pseudomonas fluorescens Pf0-1 is swarming deficient due to a point mutation in the gacA gene, which until recently was thought to inactivate rather than attenuate the Gac/Rsm pathway. As a result, little is known about the underlying mechanisms that regulate swarming motility by P. fluorescens Pf0-1. Here, we demonstrate that a ΔrsmA ΔrsmE ΔrsmI mutant, which phenotypically mimics Gac/Rsm pathway overstimulation, is proficient at swarming motility. RsmA and RsmE appear to play a key role in this regulation. Transposon mutagenesis of the ΔrsmA ΔrsmE ΔrsmI mutant identified multiple factors that impact swarming motility, including pathways involved in flagellar synthesis and biosurfactant production/secretion. We find that loss of genes linked to biosurfactant Gacamide A biosynthesis or secretion impacts swarming motility, as does loss of the alternative sigma factor FliA, which results in a defect in flagellar function. Collectively, these findings provide evidence that P. fluorescens Pf0-1 can swarm if the Gac/Rsm pathway is activated, highlight the regulatory complexity of swarming motility in this strain, and demonstrate that the cyclic lipopeptide Gacamide A is utilized as a biosurfactant for swarming motility.IMPORTANCESwarming motility is a coordinated process that allows communities of bacteria to collectively move across a surface. For P. fluorescens Pf0-1, this phenotype is notably absent in the parental strain, and to date, little is known about the regulation of swarming in this strain. Here, we identify RsmA and RsmE as key repressors of swarming motility via modulating the levels of biosurfactant production/secretion. Using transposon mutagenesis and subsequent genetic analyses, we further identify potential regulatory mechanisms of swarming motility and link Gacamide A biosynthesis and transport machinery to swarming motility.

Unique behavioral patterns of wandering colonies of Brevibacillus thermoruber on agar plates.

Brevibacillus thermoruber strain Nabari cells grow as widely spreading dendritic colonies on reasoner's 2A-agar (1.5%) plates at around 55°C but as small motile colonies at 37°C. Motile colonies can be divided into colonies that move in straight or curved lines over long distances (wandering colonies), and colonies that rotate at a fixed location (rotating colonies). The addition of surfactant to the agar medium greatly increased the frequency of wandering colonies and facilitated the study of such colonies. The morphology of the wandering colonies varied: circular at the tip and pointed at the back, lemon-shaped with pointed ends, crescent-shaped, bullet-shaped, fish-like, and so on. A single colony may split into multiple colonies as it moves, or multiple colonies may merge into a single colony. The most surprising aspect of the movement of wandering colonies was that when a moving colony collides with another colony, it sometimes does not make a U-turn, but instead retreats straight back, as if bouncing back. The migration mechanisms of wandering colonies are discussed based on optical microscopic observations of swimming patterns of single cells in water and scanning electron microscopy of the arrangement of bacterial cells in wandering colonies.

The Anti-Microbial Peptide Citrocin Controls Pseudomonas aeruginosa Biofilms by Breaking Down Extracellular Polysaccharide.

Citrocin is an anti-microbial peptide that holds great potential in animal feed. This study evaluates the anti-microbial and anti-biofilm properties of Citrocin and explores the mechanism of action of Citrocin on the biofilm of P. aeruginosa. The results showed that Citrocin had a significant inhibitory effect on the growth of P. aeruginosa with a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 0.3 mg/mL. All five concentrations (1/4MIC, 1/2MIC, MIC, 2MIC, and 4MIC) of Citrocin inhibited P. aeruginosa biofilm formation. Citrocin at the MIC, 2MIC and 4MIC removed 42.7%, 76.0% and 83.2% of mature biofilms, respectively, and suppressed the swarming motility, biofilm metabolic activity and extracellular polysaccharide production of P. aeruginosa. Metabolomics analysis indicated that 0.3 mg/mL of Citrocin up- regulated 26 and down-regulated 83 metabolites, mainly comprising amino acids, fatty acids, organic acids and sugars. Glucose and amino acid metabolic pathways, including starch and sucrose metabolism as well as arginine and proline metabolism, were highly enriched by Citrocin. In summary, our research reveals the anti-biofilm mechanism of Citrocin at the metabolic level, which provides theoretical support for the development of novel anti-biofilm strategies for combatting P. aeruginosa.

How P. aeruginosa cells with diverse stator composition collectively swarm.

Swarming is a macroscopic phenomenon in which surface bacteria organize into a motile population. The flagellar motor that drives swarming in Pseudomonas aeruginosa is powered by stators MotAB and MotCD. Deletion of the MotCD stator eliminates swarming, whereas deletion of the MotAB stator enhances swarming. Interestingly, we measured a strongly asymmetric stator availability in the wild-type (WT) strain, with MotAB stators produced at an approximately 40-fold higher level than MotCD stators. However, utilization of MotCD stators in free swimming cells requires higher liquid viscosities, while MotAB stators are readily utilized at low viscosities. Importantly, we find that cells with MotCD stators are ~10× more likely to have an active motor compared to cells uses the MotAB stators. The spectrum of motility intermittency can either cooperatively shut down or promote flagellum motility in WT populations. In P. aeruginosa, transition from a static solid-like biofilm to a dynamic liquid-like swarm is not achieved at a single critical value of flagellum torque or stator fraction but is collectively controlled by diverse combinations of flagellum activities and motor intermittencies via dynamic stator utilization. Experimental and computational results indicate that the initiation or arrest of flagellum-driven swarming motility does not occur from individual fitness or motility performance but rather related to concepts from the "jamming transition" in active granular matter.IMPORTANCEIt is now known that there exist multifactorial influences on swarming motility for P. aeruginosa, but it is not clear precisely why stator selection in the flagellum motor is so important. We show differential production and utilization of the stators. Moreover, we find the unanticipated result that the two motor configurations have significantly different motor intermittencies: the fraction of flagellum-active cells in a population on average with MotCD is active ~10× more often than with MotAB. What emerges from this complex landscape of stator utilization and resultant motor output is an intrinsically heterogeneous population of motile cells. We show how consequences of stator recruitment led to swarming motility and how the stators potentially relate to surface sensing circuitry.

Japanese honey bees (Apis cerana japonica) have swarmed more often over the last two decades.

The impacts of temperature increase are a concern for honey bees, which are major pollinators of crops and wild plants. Swarming is the reproductive behavior of honey bees that increases colony numbers. Honey bee colonies sometimes swarm multiple times, with each swarming termed a "swarming event" and a series of these events called a "swarming cycle." The number of swarming events per swarming cycle varies widely depending on climatic conditions and subspecies, and the recent temperature increase due to global warming might be affecting the number of swarming events per swarming cycle of native honey bees. We clarified long-term changes in the number of swarming events per swarming cycle of Japanese honey bees (Apis cerana japonica) by collecting beekeepers' swarming logbooks. The survey showed that between 2000 and 2022, Japanese honey bees swarmed 1 to 8 times per swarming cycle. Generalized linear model analysis indicated that year had a significant positive effect (coefficient, 0.03; 95% CI, 0.01-0.04); that is, the number of swarming events per swarming cycle showed a moderate increase over time. In addition, we found that colonies swarmed more often in a cycle when the swarming process began in early spring, especially in March. Considering the notably strong trend in Japan of warmer temperatures in March, the number of swarming events per swarming cycle may be increasing because reproduction is beginning earlier in the year. Further analyses are needed to verify the causal relationship of temperature increase on the number of swarming events per swarming cycle.

Deciphering the Interrelationship of arnT Involved in Lipid-A Alteration with the Virulence of Salmonella Typhimurium.

The lipopolysaccharide (LPS) that resides on the outermost surface and protects Gram-negative bacteria from host defenses is one of the key components leading to Salmonella infection, particularly the endotoxic lipid A domain of LPS. Lipid A modifications have been associated with several genes such as the arnT that encodes 4-amino-4-deoxy-L-arabinose transferase, which can be critical for bacteria to resist cationic antimicrobial peptides and interfere with host immune recognition. However, the association of arnT with virulence is not completely understood. Thus, this study aimed to elucidate the interrelationship of the major lipid A modification gene arnT with Salmonella Typhimurium virulence. We observed that the arnT-deficient S. Typhimurium (JOL2943), compared to the wild type (JOL401), displayed a significant decrease in several virulence phenotypes such as polymyxin B resistance, intracellular survival, swarming, and biofilm and extracellular polymeric substance (EPS) production. Interestingly, the cell-surface hydrophobicity, adhesion, and invasion characteristics remained unaffected. Additionally, LPS isolated from the mutant induced notably lower levels of endotoxicity-related cytokines in RAW and Hela cells and mice, particularly IL-1ß with a nine-fold decrease, than WT. In terms of in vivo colonization, JOL2943 showed diminished presence in internal organs such as the spleen and liver by more than 60%, while ileal infectivity remained similar to JOL401. Overall, the arnT deletion rendered the strain less virulent, with low endotoxicity, maintained gut infectivity, and reduced colonization in internal organs. With these ideal characteristics, it can be further explored as a potential attenuated Salmonella strain for therapeutics or vaccine delivery systems.

Solitary foundation or colony fission in ants: an intraspecific study shows that worker presence and number increase colony foundation success.

Dispersal and establishment strategies are highly variable. Each strategy is associated with specific costs and benefits, and understanding which factors favour or disfavour a strategy is a key issue in ecology and evolution. Ants exhibit several strategies of establishment, i.e. of colony foundation. Some species rely on winged queens that found new colonies alone when others found with accompanying workers (colony fission). The benefits conferred by these workers have been little studied and quantified, because comparing the costs and benefits of solitary foundation vs. colony fission is difficult when comparing different species. We investigated this using the ant Myrmecina graminicola, one of the few species that use both strategies. Young mated queens were allowed to found new colonies in the laboratory, with either zero (solitarily), two or four workers (colony fission). The presence of workers increased both survival and growth of the foundations over the first year, with more workers yielding higher growth. Few workers (as little as two workers) were sufficient to provide benefits, suggesting that in M. graminicola the strategy of colony fission may not dramatically decrease the number of new colonies produced compared to solitary foundation. Because queens performing solitary foundation or colony fission differ in dispersal (by flight vs. on foot), our results support the hypothesis that these two strategies of foundation coexist along a competition-colonization trade-off, where solitary foundation offers a colonization advantage, while colony fission has a competitive advantage.