Pub Date : 2024-07-01Epub Date: 2024-07-31DOI: 10.1098/rsif.2024.0100
Jacob Knight, Paula García-Galindo, Johannes Pausch, Gunnar Pruessner
Biological systems such as axonal growth cones perform chemotaxis at micrometre-level length scales, where chemotactic molecules are sparse. Such systems lie outside the range of validity of existing models, which assume smoothly varying chemical gradients. We investigate the effect of introducing discrete chemoattractant molecules by constructing a minimal dynamical model consisting of a chemotactic cell without internal memory. Significant differences are found in the behaviour of the cell as the chemical gradient is changed from smoothly varying to discrete, including the emergence of a homing radius beyond which chemotaxis is not reliably performed.
{"title":"Memoryless chemotaxis with discrete cues.","authors":"Jacob Knight, Paula García-Galindo, Johannes Pausch, Gunnar Pruessner","doi":"10.1098/rsif.2024.0100","DOIUrl":"10.1098/rsif.2024.0100","url":null,"abstract":"<p><p>Biological systems such as axonal growth cones perform chemotaxis at micrometre-level length scales, where chemotactic molecules are sparse. Such systems lie outside the range of validity of existing models, which assume smoothly varying chemical gradients. We investigate the effect of introducing <i>discrete</i> chemoattractant molecules by constructing a minimal dynamical model consisting of a chemotactic cell without internal memory. Significant differences are found in the behaviour of the cell as the chemical gradient is changed from smoothly varying to discrete, including the emergence of a homing radius beyond which chemotaxis is not reliably performed.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11289677/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141855891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01Epub Date: 2024-07-31DOI: 10.1098/rsif.2024.0123
Jonas O Wolff, Leah J Ashley, Clemens Schmitt, Celine Heu, Denitza Denkova, Maitry Jani, Veronika Řezáčová, Sean J Blamires, Stanislav N Gorb, Jessica Garb, Sara L Goodacre, Milan Řezáč
Spider webs that serve as snares are one of the most fascinating and abundant type of animal architectures. In many cases they include an adhesive coating of silk lines-so-called viscid silk-for prey capture. The evolutionary switch from silk secretions forming solid fibres to soft aqueous adhesives remains an open question in the understanding of spider silk evolution. Here we functionally and chemically characterized the secretions of two types of silk glands and their behavioural use in the cellar spider, Pholcus phalangioides. Both being derived from the same ancestral gland type that produces fibres with a solidifying glue coat, the two types produce respectively a quickly solidifying glue applied in thread anchorages and prey wraps, or a permanently tacky glue deployed in snares. We found that the latter is characterized by a high concentration of organic salts and reduced spidroin content, showing up a possible pathway for the evolution of viscid properties by hygroscopic-salt-mediated hydration of solidifying adhesives. Understanding the underlying molecular basis for such radical switches in material properties not only helps to better understand the evolutionary origins and versatility of ecologically impactful spider web architectures, but also informs the bioengineering of spider silk-based products with tailored properties.
{"title":"From fibres to adhesives: evolution of spider capture threads from web anchors by radical changes in silk gland function.","authors":"Jonas O Wolff, Leah J Ashley, Clemens Schmitt, Celine Heu, Denitza Denkova, Maitry Jani, Veronika Řezáčová, Sean J Blamires, Stanislav N Gorb, Jessica Garb, Sara L Goodacre, Milan Řezáč","doi":"10.1098/rsif.2024.0123","DOIUrl":"10.1098/rsif.2024.0123","url":null,"abstract":"<p><p>Spider webs that serve as snares are one of the most fascinating and abundant type of animal architectures. In many cases they include an adhesive coating of silk lines-so-called viscid silk-for prey capture. The evolutionary switch from silk secretions forming solid fibres to soft aqueous adhesives remains an open question in the understanding of spider silk evolution. Here we functionally and chemically characterized the secretions of two types of silk glands and their behavioural use in the cellar spider, <i>Pholcus phalangioides.</i> Both being derived from the same ancestral gland type that produces fibres with a solidifying glue coat, the two types produce respectively a quickly solidifying glue applied in thread anchorages and prey wraps, or a permanently tacky glue deployed in snares. We found that the latter is characterized by a high concentration of organic salts and reduced spidroin content, showing up a possible pathway for the evolution of viscid properties by hygroscopic-salt-mediated hydration of solidifying adhesives. Understanding the underlying molecular basis for such radical switches in material properties not only helps to better understand the evolutionary origins and versatility of ecologically impactful spider web architectures, but also informs the bioengineering of spider silk-based products with tailored properties.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11289648/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141855889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01Epub Date: 2024-07-31DOI: 10.1098/rsif.2024.0157
Ahmet Gungor, Muhammad Saif Ullah Khalid, Arman Hemmati
This study introduces novel physics-based scaling laws to estimate the propulsive performance of synchronously pitching foils in various schooling configurations. These relations are derived from quasi-steady lift-based and added mass forces. Hydrodynamic interactions among the schooling foils are considered through vortex-induced velocities imposed on them, constituting the ground effect. Generalized scaling equations are formulated for cycle-averaged coefficients of thrust and power. These equations encompass both the pure-pitching and induced velocity terms, capturing their combined effects. The equations are compared to computational results obtained from two-foil systems, exhibiting foil arrangements over a wide range of parameter space, including Strouhal number (0.15 ≤ St ≤ 0.4), pitching amplitude ([Formula: see text]) and phase difference ([Formula: see text]) at Re = 1000-10 000. The individual contributions of pure-pitching and induced velocity terms to propulsive performance elucidate that solely relying on the pure-pitching terms leads to inadequate estimation, emphasizing the significance of the induced velocity terms. The validity of the approach is further assessed by testing it with three-foil and five-foil configurations, which displays a collapse of estimated and measured results. This indicates that the scaling laws are applicable to multi-foil arrangements.
本研究介绍了基于物理学的新缩放定律,用于估算同步俯仰箔片在各种学校教育配置下的推进性能。这些关系由准稳定升力和附加质量力推导得出。通过施加在校准箔片上的涡流诱导速度(构成地面效应),考虑了校准箔片之间的流体动力学相互作用。为推力和功率的循环平均系数制定了通用比例方程。这些方程包括纯俯仰和诱导速度项,捕捉了它们的综合效应。这些方程与双箔片系统的计算结果进行了比较,显示了在 Re = 1000-10 000 条件下广泛参数空间内的箔片排列,包括斯特劳哈尔数(0.15 ≤ St ≤ 0.4)、俯仰振幅([计算公式:见正文])和相位差([计算公式:见正文])。纯俯仰项和诱导速度项对推进性能的单独贡献阐明,仅仅依靠纯俯仰项会导致估计不足,从而强调了诱导速度项的重要性。通过对三翼和五翼配置进行测试,进一步评估了该方法的有效性。这表明缩放定律适用于多翼布置。
{"title":"Physics-informed scaling laws for the performance of pitching foils in schooling configurations.","authors":"Ahmet Gungor, Muhammad Saif Ullah Khalid, Arman Hemmati","doi":"10.1098/rsif.2024.0157","DOIUrl":"10.1098/rsif.2024.0157","url":null,"abstract":"<p><p>This study introduces novel physics-based scaling laws to estimate the propulsive performance of synchronously pitching foils in various schooling configurations. These relations are derived from quasi-steady lift-based and added mass forces. Hydrodynamic interactions among the schooling foils are considered through vortex-induced velocities imposed on them, constituting the ground effect. Generalized scaling equations are formulated for cycle-averaged coefficients of thrust and power. These equations encompass both the pure-pitching and induced velocity terms, capturing their combined effects. The equations are compared to computational results obtained from two-foil systems, exhibiting foil arrangements over a wide range of parameter space, including Strouhal number (0.15 ≤ <i>St</i> ≤ 0.4), pitching amplitude ([Formula: see text]) and phase difference ([Formula: see text]) at <i>Re</i> = 1000-10 000. The individual contributions of pure-pitching and induced velocity terms to propulsive performance elucidate that solely relying on the pure-pitching terms leads to inadequate estimation, emphasizing the significance of the induced velocity terms. The validity of the approach is further assessed by testing it with three-foil and five-foil configurations, which displays a collapse of estimated and measured results. This indicates that the scaling laws are applicable to multi-foil arrangements.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11289834/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141855893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01Epub Date: 2024-07-31DOI: 10.1098/rsif.2024.0056
Veit Krause, Axel Voigt
Wrinkling instabilities of thin elastic sheets can be used to generate periodic structures over a wide range of length scales. Viscosity of the thin elastic sheet or its surrounding medium has been shown to be responsible for dynamic processes. We here consider wrinkling of fluid deformable surfaces. In contrast with thin elastic sheets, with in-plane and out-of-plane elasticity, these surfaces are characterized by in-plane viscous flow and out-of-plane elasticity and have been established as model systems for biomembranes and cellular sheets. We use this hydrodynamic theory and numerically explore the formation of wrinkles and their coarsening, either by a continuous reduction of the enclosed volume or by the continuous increase of the surface area. Both lead to almost identical results for wrinkle formation and the coarsening process, for which a scaling law for the wavenumber is obtained for a broad range of surface viscosity and rate of change of volume or area. However, for large Reynolds numbers and small changes in volume or area, wrinkling can be suppressed and surface hydrodynamics allows for global shape changes following the minimal energy configurations of the Helfrich energy for corresponding reduced volumes.
{"title":"Wrinkling of fluid deformable surfaces.","authors":"Veit Krause, Axel Voigt","doi":"10.1098/rsif.2024.0056","DOIUrl":"10.1098/rsif.2024.0056","url":null,"abstract":"<p><p>Wrinkling instabilities of thin elastic sheets can be used to generate periodic structures over a wide range of length scales. Viscosity of the thin elastic sheet or its surrounding medium has been shown to be responsible for dynamic processes. We here consider wrinkling of fluid deformable surfaces. In contrast with thin elastic sheets, with in-plane and out-of-plane elasticity, these surfaces are characterized by in-plane viscous flow and out-of-plane elasticity and have been established as model systems for biomembranes and cellular sheets. We use this hydrodynamic theory and numerically explore the formation of wrinkles and their coarsening, either by a continuous reduction of the enclosed volume or by the continuous increase of the surface area. Both lead to almost identical results for wrinkle formation and the coarsening process, for which a scaling law for the wavenumber is obtained for a broad range of surface viscosity and rate of change of volume or area. However, for large Reynolds numbers and small changes in volume or area, wrinkling can be suppressed and surface hydrodynamics allows for global shape changes following the minimal energy configurations of the Helfrich energy for corresponding reduced volumes.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11289638/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141855915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01Epub Date: 2024-07-31DOI: 10.1098/rsif.2024.0169
Arunava Nag, Floris van Breugel
Odour plumes in turbulent environments are intermittent and sparse. Laboratory-scaled experiments suggest that information about the source distance may be encoded in odour signal statistics, yet it is unclear whether useful and continuous distance estimates can be made under real-world flow conditions. Here, we analyse odour signals from outdoor experiments with a sensor moving across large spatial scales in desert and forest environments to show that odour signal statistics can yield useful estimates of distance. We show that achieving accurate estimates of distance requires integrating statistics from 5 to 10 s, with a high temporal encoding of the olfactory signal of at least 20 Hz. By combining distance estimates from a linear model with wind-relative motion dynamics, we achieved source distance estimates in a 60 × 60 m2 search area with median errors of 3-8 m, a distance at which point odour sources are often within visual range for animals such as mosquitoes.
{"title":"Odour source distance is predictable from a time history of odour statistics for large scale outdoor plumes.","authors":"Arunava Nag, Floris van Breugel","doi":"10.1098/rsif.2024.0169","DOIUrl":"10.1098/rsif.2024.0169","url":null,"abstract":"<p><p>Odour plumes in turbulent environments are intermittent and sparse. Laboratory-scaled experiments suggest that information about the source distance may be encoded in odour signal statistics, yet it is unclear whether useful and continuous distance estimates can be made under real-world flow conditions. Here, we analyse odour signals from outdoor experiments with a sensor moving across large spatial scales in desert and forest environments to show that odour signal statistics can yield useful estimates of distance. We show that achieving accurate estimates of distance requires integrating statistics from 5 to 10 s, with a high temporal encoding of the olfactory signal of at least 20 Hz. By combining distance estimates from a linear model with wind-relative motion dynamics, we achieved source distance estimates in a 60 × 60 m<sup>2</sup> search area with median errors of 3-8 m, a distance at which point odour sources are often within visual range for animals such as mosquitoes.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11288670/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141855892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01Epub Date: 2024-07-31DOI: 10.1098/rsif.2024.0111
Amy J Wood-Yang, Brandon G Gerberich, Mark R Prausnitz
Selective scleral crosslinking has been proposed as a novel treatment to increase scleral stiffness to counteract biomechanical changes associated with glaucoma and high myopia. Scleral stiffening has been shown by transpupillary peripapillary scleral photocrosslinking in rats, where the photosensitizer, methylene blue (MB), was injected retrobulbarly and red light initiated crosslinking reactions with collagen. Here, we adapted a computational model previously developed to model this treatment in rat eyes to additionally model MB photocrosslinking in minipigs and humans. Increased tissue length and subsequent diffusion and light penetration limitations were found to be barriers to achieving the same extent of crosslinking as in rats. Per cent inspired O2, injected MB concentration and laser fluence were simultaneously varied to overcome these limitations and used to determine optimal combinations of treatment parameters in rats, minipigs and humans. Increasing these three treatment parameters simultaneously resulted in maximum crosslinking, except in rats, where the highest MB concentrations decreased crosslinking. Additionally, the kinetics and diffusion of photocrosslinking reaction intermediates and unproductive side products were modelled across space and time. The model provides a mechanistic understanding of MB photocrosslinking in scleral tissue and a basis for adapting and screening treatment parameters in larger animal models and, eventually, human eyes.
{"title":"Computational modelling of scleral photocrosslinking: from rat to minipig to human.","authors":"Amy J Wood-Yang, Brandon G Gerberich, Mark R Prausnitz","doi":"10.1098/rsif.2024.0111","DOIUrl":"10.1098/rsif.2024.0111","url":null,"abstract":"<p><p>Selective scleral crosslinking has been proposed as a novel treatment to increase scleral stiffness to counteract biomechanical changes associated with glaucoma and high myopia. Scleral stiffening has been shown by transpupillary peripapillary scleral photocrosslinking in rats, where the photosensitizer, methylene blue (MB), was injected retrobulbarly and red light initiated crosslinking reactions with collagen. Here, we adapted a computational model previously developed to model this treatment in rat eyes to additionally model MB photocrosslinking in minipigs and humans. Increased tissue length and subsequent diffusion and light penetration limitations were found to be barriers to achieving the same extent of crosslinking as in rats. Per cent inspired O<sub>2</sub>, injected MB concentration and laser fluence were simultaneously varied to overcome these limitations and used to determine optimal combinations of treatment parameters in rats, minipigs and humans. Increasing these three treatment parameters simultaneously resulted in maximum crosslinking, except in rats, where the highest MB concentrations decreased crosslinking. Additionally, the kinetics and diffusion of photocrosslinking reaction intermediates and unproductive side products were modelled across space and time. The model provides a mechanistic understanding of MB photocrosslinking in scleral tissue and a basis for adapting and screening treatment parameters in larger animal models and, eventually, human eyes.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11289678/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141855886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01Epub Date: 2024-06-21DOI: 10.1098/rsif.2023.0779
Brendan Latham, Andrew Reid, Joseph C Jackson-Camargo, Jonathan A Williams, James F C Windmill
Many animals employ a second frequency filter beyond the initial filtering of the eardrum (or tympanal membrane). In the field cricket ear, both the filtering mechanism and the transmission path from the posterior tympanal membrane (PTM) have remained unclear. A mismatch between PTM vibrations and sensilla tuning has prompted speculations of a second filter. PTM coupling to the tracheal branches is suggested to support a transmission pathway. Here, we present three independent lines of evidence converging on the same conclusion: the existence of a series of linked membranes with distinct resonant frequencies serving both filtering and transmission functions. Micro-computed tomography (µ-CT) highlighted the 'dividing membrane (DivM)', separating the tracheal branches and connected to the PTM via the dorsal membrane of the posterior tracheal branch (DM-PTB). Thickness analysis showed the DivM to share significant thinness similarity with the PTM. Laser Doppler vibrometry indicated the first of two PTM vibrational peaks, at 6 and 14 kHz, originates not from the PTM but from the coupled DM-PTB. This result was corroborated by µ-CT-based finite element analysis. These findings clarify further the biophysical source of neuroethological pathways in what is an important model of behavioural neuroscience. Tuned microscale coupled membranes may also hold biomimetic relevance.
{"title":"Coupled membranes: a mechanism of frequency filtering and transmission in the field cricket ear evidenced by micro-computed tomography, laser Doppler vibrometry and finite element analysis.","authors":"Brendan Latham, Andrew Reid, Joseph C Jackson-Camargo, Jonathan A Williams, James F C Windmill","doi":"10.1098/rsif.2023.0779","DOIUrl":"10.1098/rsif.2023.0779","url":null,"abstract":"<p><p>Many animals employ a second frequency filter beyond the initial filtering of the eardrum (or tympanal membrane). In the field cricket ear, both the filtering mechanism and the transmission path from the posterior tympanal membrane (PTM) have remained unclear. A mismatch between PTM vibrations and sensilla tuning has prompted speculations of a second filter. PTM coupling to the tracheal branches is suggested to support a transmission pathway. Here, we present three independent lines of evidence converging on the same conclusion: the existence of a series of linked membranes with distinct resonant frequencies serving both filtering and transmission functions. Micro-computed tomography (µ-CT) highlighted the 'dividing membrane (DivM)', separating the tracheal branches and connected to the PTM via the dorsal membrane of the posterior tracheal branch (DM-PTB). Thickness analysis showed the DivM to share significant thinness similarity with the PTM. Laser Doppler vibrometry indicated the first of two PTM vibrational peaks, at 6 and 14 kHz, originates not from the PTM but from the coupled DM-PTB. This result was corroborated by µ-CT-based finite element analysis. These findings clarify further the biophysical source of neuroethological pathways in what is an important model of behavioural neuroscience. Tuned microscale coupled membranes may also hold biomimetic relevance.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11285747/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141432184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01Epub Date: 2024-06-20DOI: 10.1098/rsif.2023.0756
Marie Haghebaert, Béatrice Laroche, Lorenzo Sala, Stanislas Mondot, Joël Doré
The health and well-being of a host are deeply influenced by the interactions with its gut microbiota. Contrasted environmental conditions, such as diseases or dietary habits, play a pivotal role in modulating these interactions, impacting microbiota composition and functionality. Such conditions can also lead to transitions from beneficial to detrimental symbiosis, viewed as alternative stable states of the host-microbiota dialogue. This article introduces a novel mathematical model exploring host-microbiota interactions, integrating dynamics of the colonic epithelial crypt, microbial metabolic functions, inflammation sensitivity and colon flows in a transverse section. The model considers metabolic shifts in epithelial cells based on butyrate and hydrogen sulfide concentrations, innate immune pattern recognition receptor activation, microbial oxygen tolerance and the impact of antimicrobial peptides on the microbiota. Using the model, we demonstrated that a high-protein, low-fibre diet exacerbates detrimental interactions and compromises beneficial symbiotic resilience, underscoring a destabilizing effect towards an unhealthy state. Moreover, the proposed model provides essential insights into oxygen levels, fibre and protein breakdown, and basic mechanisms of innate immunity in the colon and offers a crucial understanding of factors influencing the colon environment.
{"title":"A mechanistic modelling approach of the host-microbiota interactions to investigate beneficial symbiotic resilience in the human gut.","authors":"Marie Haghebaert, Béatrice Laroche, Lorenzo Sala, Stanislas Mondot, Joël Doré","doi":"10.1098/rsif.2023.0756","DOIUrl":"10.1098/rsif.2023.0756","url":null,"abstract":"<p><p>The health and well-being of a host are deeply influenced by the interactions with its gut microbiota. Contrasted environmental conditions, such as diseases or dietary habits, play a pivotal role in modulating these interactions, impacting microbiota composition and functionality. Such conditions can also lead to transitions from beneficial to detrimental symbiosis, viewed as alternative stable states of the host-microbiota dialogue. This article introduces a novel mathematical model exploring host-microbiota interactions, integrating dynamics of the colonic epithelial crypt, microbial metabolic functions, inflammation sensitivity and colon flows in a transverse section. The model considers metabolic shifts in epithelial cells based on butyrate and hydrogen sulfide concentrations, innate immune pattern recognition receptor activation, microbial oxygen tolerance and the impact of antimicrobial peptides on the microbiota. Using the model, we demonstrated that a high-protein, low-fibre diet exacerbates detrimental interactions and compromises beneficial symbiotic resilience, underscoring a destabilizing effect towards an unhealthy state. Moreover, the proposed model provides essential insights into oxygen levels, fibre and protein breakdown, and basic mechanisms of innate immunity in the colon and offers a crucial understanding of factors influencing the colon environment.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11285522/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141432183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01Epub Date: 2024-06-25DOI: 10.1098/rsif.2024.0042
Daniel C P Jorge, Ricardo Martinez-Garcia
The component Allee effect (AE) is the positive correlation between an organism's fitness component and population density. Depending on the population spatial structure, which determines the interactions between organisms, a component AE might lead to positive density dependence in the population per-capita growth rate and establish a demographic AE. However, existing spatial models impose a fixed population spatial structure, which limits the understanding of how a component AE and spatial dynamics jointly determine the existence of demographic AEs. We introduce a spatially explicit theoretical framework where spatial structure and population dynamics are emergent properties of the individual-level demographic and movement rates. This framework predicts various spatial patterns depending on its specific parametrization, including evenly spaced aggregates of organisms, which determine the demographic-level by-products of the component AE. We find that aggregation increases population abundance and allows population survival in harsher environments and at lower global population densities when compared with uniformly distributed organisms. Moreover, aggregation can prevent the component AE from manifesting at the population level or restrict it to the level of each independent aggregate. These results provide a mechanistic understanding of how component AEs might operate for different spatial structures and manifest at larger scales.
{"title":"Demographic effects of aggregation in the presence of a component Allee effect.","authors":"Daniel C P Jorge, Ricardo Martinez-Garcia","doi":"10.1098/rsif.2024.0042","DOIUrl":"10.1098/rsif.2024.0042","url":null,"abstract":"<p><p>The component Allee effect (AE) is the positive correlation between an organism's fitness component and population density. Depending on the population spatial structure, which determines the interactions between organisms, a component AE might lead to positive density dependence in the population per-capita growth rate and establish a demographic AE. However, existing spatial models impose a fixed population spatial structure, which limits the understanding of how a component AE and spatial dynamics jointly determine the existence of demographic AEs. We introduce a spatially explicit theoretical framework where spatial structure and population dynamics are emergent properties of the individual-level demographic and movement rates. This framework predicts various spatial patterns depending on its specific parametrization, including evenly spaced aggregates of organisms, which determine the demographic-level by-products of the component AE. We find that aggregation increases population abundance and allows population survival in harsher environments and at lower global population densities when compared with uniformly distributed organisms. Moreover, aggregation can prevent the component AE from manifesting at the population level or restrict it to the level of each independent aggregate. These results provide a mechanistic understanding of how component AEs might operate for different spatial structures and manifest at larger scales.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11286165/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141446432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01Epub Date: 2024-06-05DOI: 10.1098/rsif.2023.0594
Shun Gao, Yuan Liu, Bin Wu
The speed of evolution on structured populations is crucial for biological and social systems. The likelihood of invasion is key for evolutionary stability. But it makes little sense if it takes long. It is far from known what population structure slows down evolution. We investigate the absorption time of a single neutral mutant for all the 112 non-isomorphic undirected graphs of size 6. We find that about three-quarters of the graphs have an absorption time close to that of the complete graph, less than one-third are accelerators, and more than two-thirds are decelerators. Surprisingly, determining whether a graph has a long absorption time is too complicated to be captured by the joint degree distribution. Via the largest sojourn time, we find that echo-chamber-like graphs, which consist of two homogeneous graphs connected by few sparse links, are likely to slow down absorption. These results are robust for large graphs, mutation patterns as well as evolutionary processes. This work serves as a benchmark for timing evolution with complex interactions, and fosters the understanding of polarization in opinion formation.
{"title":"The speed of neutral evolution on graphs.","authors":"Shun Gao, Yuan Liu, Bin Wu","doi":"10.1098/rsif.2023.0594","DOIUrl":"10.1098/rsif.2023.0594","url":null,"abstract":"<p><p>The speed of evolution on structured populations is crucial for biological and social systems. The likelihood of invasion is key for evolutionary stability. But it makes little sense if it takes long. It is far from known what population structure slows down evolution. We investigate the absorption time of a single neutral mutant for all the 112 non-isomorphic undirected graphs of size 6. We find that about three-quarters of the graphs have an absorption time close to that of the complete graph, less than one-third are accelerators, and more than two-thirds are decelerators. Surprisingly, determining whether a graph has a long absorption time is too complicated to be captured by the joint degree distribution. Via the largest sojourn time, we find that echo-chamber-like graphs, which consist of two homogeneous graphs connected by few sparse links, are likely to slow down absorption. These results are robust for large graphs, mutation patterns as well as evolutionary processes. This work serves as a benchmark for timing evolution with complex interactions, and fosters the understanding of polarization in opinion formation.</p>","PeriodicalId":17488,"journal":{"name":"Journal of The Royal Society Interface","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11346635/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141247148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}