scholarly journals Predatory Bacteria Select for Sustained Prey Diversity

2021 ◽  
Vol 9 (10) ◽  
pp. 2079
Author(s):  
Ramith R. Nair ◽  
Gregory J. Velicer
Keyword(s):  
Myxococcus Xanthus ◽  
Frequency Dependent Selection ◽  
Predator Prey ◽  
Prey Diversity ◽  
Predatory Bacteria ◽  
Negative Frequency Dependent Selection ◽  
Diversity Dynamics ◽  
Time Point ◽  
Prey Populations

Predator impacts on prey diversity are often studied among higher organisms over short periods, but microbial predator-prey systems allow examination of prey-diversity dynamics over evolutionary timescales. We previously showed that Escherichia coli commonly evolved minority mucoid phenotypes in response to predation by the bacterial predator Myxococcus xanthus by one time point of a coevolution experiment now named MyxoEE-6. Here we examine mucoid frequencies across several MyxoEE-6 timepoints to discriminate between the hypotheses that mucoids were increasing to fixation, stabilizing around equilibrium frequencies, or heading to loss toward the end of MyxoEE-6. In four focal coevolved prey populations, mucoids rose rapidly early in the experiment and then fluctuated within detectable minority frequency ranges through the end of MyxoEE-6, generating frequency dynamics suggestive of negative frequency-dependent selection. However, a competition experiment between mucoid and non-mucoid clones found a predation-specific advantage of the mucoid clone that was insensitive to frequency over the examined range, leaving the mechanism that maintains minority mucoidy unresolved. The advantage of mucoidy under predation was found to be associated with reduced population size after growth (productivity) in the absence of predators, suggesting a tradeoff between productivity and resistance to predation that we hypothesize may reverse mucoid vs non-mucoid fitness ranks within each MyxoEE-6 cycle. We also found that mucoidy was associated with diverse colony phenotypes and diverse candidate mutations primarily localized in the exopolysaccharide operon yjbEFGH. Collectively, our results show that selection from predatory bacteria can generate apparently stable sympatric phenotypic polymorphisms within coevolving prey populations and also allopatric diversity across populations by selecting for diverse mutations and colony phenotypes associated with mucoidy. More broadly, our results suggest that myxobacterial predation increases long-term diversity within natural microbial communities.

scholarly journals Negative frequency-dependent selection and asymmetrical transformation stabilise multi-strain bacterial population structures

2021 ◽  
Author(s):  
Gabrielle L. Harrow ◽  
John A. Lees ◽  
William P. Hanage ◽  
Marc Lipsitch ◽  
Jukka Corander ◽  
...  
Keyword(s):  
Bacterial Population ◽  
Genomic Data ◽  
Genetic Distances ◽  
Outbreeding Depression ◽  
Short Term ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Population Structures ◽  
Negative Frequency Dependent Selection

AbstractStreptococcus pneumoniae can be divided into many strains, each a distinct set of isolates sharing similar core and accessory genomes, which co-circulate within the same hosts. Previous analyses suggested the short-term vaccine-associated dynamics of S. pneumoniae strains may be mediated through multi-locus negative frequency-dependent selection (NFDS), which maintains accessory loci at equilibrium frequencies. Long-term simulations demonstrated NFDS stabilised clonally-evolving multi-strain populations through preventing the loss of variation through drift, based on polymorphism frequencies, pairwise genetic distances and phylogenies. However, allowing symmetrical recombination between isolates evolving under multi-locus NFDS generated unstructured populations of diverse genotypes. Replication of the observed data improved when multi-locus NFDS was combined with recombination that was instead asymmetrical, favouring deletion of accessory loci over insertion. This combination separated populations into strains through outbreeding depression, resulting from recombinants with reduced accessory genomes having lower fitness than their parental genotypes. Although simplistic modelling of recombination likely limited these simulations’ ability to maintain some properties of genomic data as accurately as those lacking recombination, the combination of asymmetrical recombination and multi-locus NFDS could restore multi-strain population structures from randomised initial populations. As many bacteria inhibit insertions into their chromosomes, this combination may commonly underlie the co-existence of strains within a niche.

scholarly journals Functional genomics study of Pseudomonas putida to determine traits associated with avoidance of a myxobacterial predator

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shukria Akbar ◽  
D. Cole Stevens
Keyword(s):  
Pseudomonas Putida ◽  
Bacterial Communities ◽  
Predator Avoidance ◽  
Phenotypic Diversity ◽  
Myxococcus Xanthus ◽  
Predator Prey ◽  
Mucoid Conversion ◽  
Small Colony ◽  
Predator Prey Models ◽  
Insight Into

AbstractPredation contributes to the structure and diversity of microbial communities. Predatory myxobacteria are ubiquitous to a variety of microbial habitats and capably consume a broad diversity of microbial prey. Predator–prey experiments utilizing myxobacteria have provided details into predatory mechanisms and features that facilitate consumption of prey. However, prey resistance to myxobacterial predation remains underexplored, and prey resistances have been observed exclusively from predator–prey experiments that included the model myxobacterium Myxococcus xanthus. Utilizing a predator–prey pairing that instead included the myxobacterium, Cystobacter ferrugineus, with Pseudomonas putida as prey, we observed surviving phenotypes capable of eluding predation. Comparative transcriptomics between P. putida unexposed to C. ferrugineus and the survivor phenotype suggested that increased expression of efflux pumps, genes associated with mucoid conversion, and various membrane features contribute to predator avoidance. Unique features observed from the survivor phenotype when compared to the parent P. putida include small colony variation, efflux-mediated antibiotic resistance, phenazine-1-carboxylic acid production, and increased mucoid conversion. These results demonstrate the utility of myxobacterial predator–prey models and provide insight into prey resistances in response to predatory stress that might contribute to the phenotypic diversity and structure of bacterial communities.

scholarly journals Determining transition readiness in Swiss childhood cancer survivors – a feasibility study

BMC Cancer ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Maria Otth ◽  
Patrick Wechsler ◽  
Sibylle Denzler ◽  
Henrik Koehler ◽  
Katrin Scheinemann
Keyword(s):  
Health Care ◽  
Cancer Survivors ◽  
Childhood Cancer ◽  
Childhood Cancer Survivors ◽  
Self Management ◽  
Transition Readiness ◽  
Long Term Follow Up ◽  
Time Point

Abstract Background The successful transition of childhood cancer survivors (CCSs) from pediatric to adult long-term follow-up care is a critical phase, and determining the right time point can be challenging. We assessed the feasibility of the use of existing transition readiness tools in the context of the Swiss health care system, assessed partly transition readiness in Swiss CCSs, and compared our findings with Canadian CCSs for which these tools were originally developed. Methods We officially translated the Cancer Worry Scale (CWS) and Self-Management Skill Scale (SMSS) into German and integrated them into this cross-sectional study. We included CCSs attending the long-term follow-up (LTFU) clinic in the Division of Oncology-Hematology, Department of Pediatrics, Kantonsspital Aarau. We used descriptive statistics to describe transition readiness. Results We randomly recruited 50 CCSs aged ≥18 years at participation. The CCSs had a median CWS score of 62 (interquartile range 55–71), indicating a moderate level of cancer-related worry. Despite high self-management skills, some answers showed a dependency of CCSs on their parents. Our experience shows that the CWS and SMSS are easy for Swiss CCSs to use, understand, and complete. The interpretation of the results must take differences in health care systems between countries into account. Conclusions The translated CWS and SMSS are appropriate additional measures to assess transition readiness in CCSs. These scales can be used longitudinally to find the individual time point for transition and the completion by CCSs enables the health care team to individualize the transition process and to support the CCSs according to their individual needs.

scholarly journals Debridement, Antibiotics, and Implant Retention Is a Viable Treatment Option for Early Periprosthetic Joint Infection Presenting More Than 4 Weeks After Index Arthroplasty

2019 ◽  
Vol 71 (3) ◽  
pp. 630-636 ◽  
Author(s):  
Claudia A M Löwik ◽  
Javad Parvizi ◽  
Paul C Jutte ◽  
Wierd P Zijlstra ◽  
Bas A S Knobben ◽  
...  
Keyword(s):  
Treatment Failure ◽  
Periprosthetic Joint Infection ◽  
Joint Infection ◽  
Viable Option ◽  
Time Intervals ◽  
Implant Retention ◽  
Time Point ◽  
Viable Treatment

Abstract Background The success of debridement, antibiotics, and implant retention (DAIR) in early periprosthetic joint infection (PJI) largely depends on the presence of a mature biofilm. At what time point DAIR should be disrecommended is unknown. This multicenter study evaluated the outcome of DAIR in relation to the time after index arthroplasty. Methods We retrospectively evaluated PJIs occurring within 90 days after surgery and treated with DAIR. Patients with bacteremia, arthroscopic debridements, and a follow-up <1 year were excluded. Treatment failure was defined as (1) any further surgical procedure related to infection; (2) PJI-related death; or (3) use of long-term suppressive antibiotics. Results We included 769 patients. Treatment failure occurred in 294 patients (38%) and was similar between time intervals from index arthroplasty to DAIR: the failure rate for Week 1–2 was 42% (95/226), the rate for Week 3–4 was 38% (143/378), the rate for Week 5–6 was 29% (29/100), and the rate for Week 7–12 was 42% (27/65). An exchange of modular components was performed to a lesser extent in the early post-surgical course compared with the late course (41% vs 63%, respectively; P < .001). The causative microorganisms, comorbidities, and durations of symptoms were comparable between time intervals. Conclusions DAIR is a viable option in patients with early PJI presenting more than 4 weeks after index surgery, as long as DAIR is performed within at least 1 week after the onset of symptoms and modular components can be exchanged.

scholarly journals Long-term UVB exposure promotes predator-inspection behaviour in a fish

2017 ◽  
Vol 13 (12) ◽  
pp. 20170497 ◽  
Author(s):  
Simon Vitt ◽  
Janina E. Zierul ◽  
Theo C. M. Bakker ◽  
Ingolf P. Rick
Keyword(s):  
Gasterosteus Aculeatus ◽  
Stratospheric Ozone ◽  
Ultraviolet B ◽  
Antipredator Behaviour ◽  
Uvb Radiation ◽  
Ecological Processes ◽  
Predator Prey ◽  
Natural Sunlight ◽  
Predator Inspection

Ultraviolet-B radiation (UVB) reaching the earth's surface has increased due to human-caused stratospheric ozone depletion. Whereas the harmful effects of UVB on aquatic organisms are well studied at the molecular and cellular level, recent studies have also begun to address behavioural changes caused by sublethal amounts of UVB. However, the behavioural consequences of long-term exposure to ecologically relevant UVB levels over several life stages are virtually unknown, particularly with regard to predator–prey behaviour. We found increased predator-inspection behaviour together with a smaller body length in three-spined sticklebacks ( Gasterosteus aculeatus ) after fish were exposed for about seven months to natural sunlight conditions with enhanced UVB, compared with full siblings exposed to natural sunlight only. The observed change in antipredator behaviour may reflect a direct behavioural response mediated through UVB-induced oxidative stress during development. Alternatively, the smaller body size in UVB-exposed fish may result in an increased inspection effort allowing them to spend more time foraging. Our findings suggest that, within the scope of environmental change, UVB radiation constitutes an important stress factor by eliciting behavioural responses that influence crucial ecological processes, such as predator–prey interactions.

scholarly journals Consistency in mutualism relies on local, rather than wider community biodiversity

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Katie Dunkley ◽  
Jo Cable ◽  
Sarah E. Perkins
Keyword(s):  
Biodiversity Loss ◽  
Context Dependency ◽  
Third Party ◽  
Interaction Patterns ◽  
Specific Time ◽  
Specific Time Point ◽  
Service Resource ◽  
Resource Mutualism ◽  
Time Point

AbstractMutualistic interactions play a major role in shaping the Earth’s biodiversity, yet the consistent drivers governing these beneficial interactions are unknown. Using a long-term (8 year, including > 256 h behavioural observations) dataset of the interaction patterns of a service-resource mutualism (the cleaner-client interaction), we identified consistent and dynamic predictors of mutualistic outcomes. We showed that cleaning was consistently more frequent when the presence of third-party species and client partner abundance locally increased (creating choice options), whilst partner identity regulated client behaviours. Eight of our 12 predictors of cleaner and client behaviour played a dynamic role in predicting both the quality (duration) and quantity (frequency) of interactions, and we suggest that the environmental context acting on these predictors at a specific time point will indirectly regulate their role in cleaner-client interaction patterns: context-dependency can hence regulate mutualisms both directly and indirectly. Together our study highlights that consistency in cleaner-client mutualisms relies strongly on the local, rather than wider community—with biodiversity loss threatening all environments this presents a worrying future for the pervasiveness of mutualisms.

scholarly journals A geographic cline induced by negative frequency-dependent selection

2011 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuma Takahashi ◽  
Satoru Morita ◽  
Jin Yoshimura ◽  
Mamoru Watanabe
Keyword(s):  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Negative Frequency Dependent Selection

scholarly journals Intruder colour and light environment jointly determine how nesting male stickleback respond to simulated territorial intrusions

2016 ◽  
Vol 12 (8) ◽  
pp. 20160467 ◽  
Author(s):  
Daniel I. Bolnick ◽  
Kimberly Hendrix ◽  
Lyndon Alexander Jordan ◽  
Thor Veen ◽  
Chad D. Brock
Keyword(s):  
Frequency Dependence ◽  
Three Dimensional ◽  
Light Environment ◽  
Depth Gradient ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Negative Frequency Dependent Selection ◽  
Colour Signals

Variation in male nuptial colour signals might be maintained by negative frequency-dependent selection. This can occur if males are more aggressive towards rivals with locally common colour phenotypes. To test this hypothesis, we introduced red or melanic three-dimensional printed-model males into the territories of nesting male stickleback from two optically distinct lakes with different coloured residents. Red-throated models were attacked more in the population with red males, while melanic models were attacked more in the melanic male lake. Aggression against red versus melanic models also varied across a depth gradient within each lake, implying that the local light environment also modulated the strength of negative frequency dependence acting on male nuptial colour.

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