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Cass JF, Bloomfield-Gadêlha H. The reaction-diffusion basis of animated patterns in eukaryotic flagella. Nat Commun 2023; 14:5638. [PMID: 37758714 PMCID: PMC10533521 DOI: 10.1038/s41467-023-40338-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 07/20/2023] [Indexed: 09/29/2023] Open
Abstract
The flagellar beat of bull spermatozoa and C. Reinhardtii are modelled by a minimal, geometrically exact, reaction-diffusion system. Spatio-temporal animated patterns describe flagellar waves, analogous to chemical-patterns from classical reaction-diffusion systems, with sliding-controlled molecular motor reaction-kinetics. The reaction-diffusion system is derived from first principles as a consequence of the high-internal dissipation by the flagellum relative to the external hydrodynamic dissipation. Quantitative comparison with nonlinear, large-amplitude simulations shows that animated reaction-diffusion patterns account for the experimental beating of both bull sperm and C. Reinhardtii. Our results suggest that a unified mechanism may exist for motors controlled by sliding, without requiring curvature-sensing, and uninfluenced by hydrodynamics. High-internal dissipation instigates autonomous travelling waves independently of the external fluid, enabling progressive swimming, otherwise not possible, in low viscosity environments, potentially critical for external fertilizers and aquatic microorganisms. The reaction-diffusion system may prove a powerful tool for studying pattern formation of movement on animated structures.
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Affiliation(s)
- James F Cass
- School of Engineering Mathematics and Technology, and Bristol Robotics Laboratory, University of Bristol, Bristol, UK
| | - Hermes Bloomfield-Gadêlha
- School of Engineering Mathematics and Technology, and Bristol Robotics Laboratory, University of Bristol, Bristol, UK.
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2
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Nath B, Caprini L, Maggi C, Zizzari A, Arima V, Viola I, Di Leonardo R, Puglisi A. A microfluidic method for passive trapping of sperms in microstructures. LAB ON A CHIP 2023; 23:773-784. [PMID: 36723114 DOI: 10.1039/d2lc00997h] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Sperm motility is a prerequisite for male fertility. Enhancing the concentration of motile sperms in assisted reproductive technologies - for human and animal reproduction - is typically achieved through aggressive methods such as centrifugation. Here, we propose a passive technique for the amplification of motile sperm concentration, with no externally imposed forces or flows. The technique is based on the disparity between probability rates, for motile cells, of entering and escaping from complex structures. The effectiveness of the technique is demonstrated in microfluidic experiments with microstructured devices, comparing the trapping power in different geometries. In these micro-traps, we observe an enhancement of cells' concentration close to 10, with a contrast between motile and non-motile cells increased by a similar factor. Simulations of suitable interacting model sperms in realistic geometries reproduce quantitatively the experimental results, extend the range of observations and highlight the components that are key to the optimal trap design.
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Affiliation(s)
- Binita Nath
- ISC-CNR, Institute for Complex Systems, Piazzale A. Moro 2, I-00185 Rome, Italy
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185, Rome, Italy
- Department of Mechanical Engineering, National Institute of Technology Silchar, Silchar - 788010, Assam, India
| | - Lorenzo Caprini
- Heinrich-Heine-Universität Düsseldorf, Institut für Theoretische Physik II - Soft Matter, D-40225 Düsseldorf, Germany.
| | - Claudio Maggi
- NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter Laboratory, c/o Dipt. di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185, Rome, Italy
| | - Alessandra Zizzari
- NANOTEC-CNR, Institute of Nanotechnology, c/o Campus Ecotekne, University of Salento, Via Monteroni, I-73100, Lecce, Italy
| | - Valentina Arima
- NANOTEC-CNR, Institute of Nanotechnology, c/o Campus Ecotekne, University of Salento, Via Monteroni, I-73100, Lecce, Italy
| | - Ilenia Viola
- NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter Laboratory, c/o Dipt. di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185, Rome, Italy
| | - Roberto Di Leonardo
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185, Rome, Italy
- NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter Laboratory, c/o Dipt. di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185, Rome, Italy
| | - Andrea Puglisi
- ISC-CNR, Institute for Complex Systems, Piazzale A. Moro 2, I-00185 Rome, Italy
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185, Rome, Italy
- INFN, Unità di Roma Tor Vergata, 00133 Rome, Italy
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3
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Graziano M, Palit S, Yethiraj A, Immler S, Gage MJG, Purchase CF. Frequency-dependent viscosity of salmon ovarian fluid has biophysical implications for sperm-egg interactions. J Exp Biol 2023; 226:285939. [PMID: 36511132 PMCID: PMC10086386 DOI: 10.1242/jeb.244712] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 12/02/2022] [Indexed: 12/15/2022]
Abstract
Gamete-level sexual selection of externally fertilising species is usually achieved by modifying sperm behaviour with mechanisms that alter the chemical environment in which gametes perform. In fish, this can be accomplished through the ovarian fluid, a substance released with the eggs at spawning. While the biochemical effects of ovarian fluid in relation to sperm energetics have been investigated, the influence of the physical environment in which sperm compete remains poorly explored. Our objective was therefore to gain insights on the physical structure of this fluid and potential impacts on reproduction. Using soft-matter physics approaches of steady-state and oscillatory viscosity measurements, we subjected wild Atlantic salmon ovarian fluids to variable shear stresses and frequencies resembling those exerted by sperm swimming through the fluid near eggs. We show that this fluid, which in its relaxed state is a gel-like substance, displays a non-Newtonian viscoelastic and shear-thinning profile, where the viscosity decreases with increasing shear rates. We concurrently find that this fluid obeys the Cox-Merz rule below 7.6 Hz and infringes it above this level, thus indicating a shear-thickening phase where viscosity increases provided it is probed gently enough. This suggests the presence of a unique frequency-dependent structural network with relevant implications for sperm energetics and fertilisation dynamics. This article has an associated ECR Spotlight interview with Marco Graziano.
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Affiliation(s)
- Marco Graziano
- Department of Biology, Memorial University, St. John's, Newfoundland and Labrador, A1B 3X9, Canada.,Department of Biological Sciences, Centre for Ecology, Evolution, and Conservation, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Swomitra Palit
- Department of Physics and Physical Oceanography, Soft Matter Lab, Memorial University, St. John's, Newfoundland and Labrador, A1B 3X7, Canada
| | - Anand Yethiraj
- Department of Physics and Physical Oceanography, Soft Matter Lab, Memorial University, St. John's, Newfoundland and Labrador, A1B 3X7, Canada
| | - Simone Immler
- Department of Biological Sciences, Centre for Ecology, Evolution, and Conservation, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Matthew J G Gage
- Department of Biological Sciences, Centre for Ecology, Evolution, and Conservation, University of East Anglia, Norwich NR4 7TJ, United Kingdom.,Deceased
| | - Craig F Purchase
- Department of Biology, Memorial University, St. John's, Newfoundland and Labrador, A1B 3X9, Canada
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Tomaiuolo G, Fellico F, Preziosi V, Guido S. Semen rheology and its relation to male infertility. Interface Focus 2022; 12:20220048. [PMID: 36330323 PMCID: PMC9560795 DOI: 10.1098/rsfs.2022.0048] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 08/30/2022] [Indexed: 08/01/2023] Open
Abstract
Infertility affects 15% of couples of reproductive age worldwide. In spite of many advances in understanding and treating male infertility, there is still a number of issues that need further investigation and translation to the clinic. Here, we review the current knowledge and practice concerning semen rheology and its relation with pathological states affecting male infertility. Although it is well recognized that altered rheological properties of semen can impair normal sperm movement in the female reproductive tract, routine semen analysis is mostly focused on number, motility and morphology of spermatozoa, and includes only an approximate, operator-dependent measure of semen viscosity. The latter is based on the possible formation of a liquid thread from a pipette where a semen sample has been aspirated, a method that is sensitive not only to viscosity but also to elongational properties and surface tension of semen. The formation of a liquid thread is usually associated with a gel-like consistency of the sample and changes in spermatozoa motility in such a complex medium are still to be fully elucidated. The aim of this review is to point out that a more quantitative and reliable characterization of semen rheology is in order to improve the current methods of semen analysis and to develop additional tools for the diagnosis and treatment of male infertility.
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Affiliation(s)
- Giovanna Tomaiuolo
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, Naples, Italy
- CEINGE Advanced Biotechnologies, Via Gaetano Salvatore 486, 80145 Napoli, Italy
| | - Fiammetta Fellico
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, Naples, Italy
- CEINGE Advanced Biotechnologies, Via Gaetano Salvatore 486, 80145 Napoli, Italy
| | - Valentina Preziosi
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, Naples, Italy
- CEINGE Advanced Biotechnologies, Via Gaetano Salvatore 486, 80145 Napoli, Italy
| | - Stefano Guido
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, Naples, Italy
- CEINGE Advanced Biotechnologies, Via Gaetano Salvatore 486, 80145 Napoli, Italy
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Biophysical Determinants and Constraints on Sperm Swimming Velocity. Cells 2022; 11:cells11213360. [DOI: 10.3390/cells11213360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 10/14/2022] [Accepted: 10/20/2022] [Indexed: 11/17/2022] Open
Abstract
Over the last 50 years, sperm competition has become increasingly recognised as a potent evolutionary force shaping male ejaculate traits. One such trait is sperm swimming speed, with faster sperm associated with increased fertilisation success in some species. Consequently, sperm are often thought to have evolved to be longer in order to facilitate faster movement. However, despite the intrinsic appeal of this argument, sperm operate in a different biophysical environment than we are used to, and instead increasing length may not necessarily be associated with higher velocity. Here, we test four predictive models (ConstantPower Density, Constant Speed, Constant Power Transfer, Constant Force) of the relationship between sperm length and speed. We collated published data on sperm morphology and velocity from 141 animal species, tested for structural clustering of sperm morphology and then compared the model predictions across all morphologically similar sperm clusters. Within four of five morphological clusters of sperm, we did not find a significant positive relationship between total sperm length and velocity. Instead, in four morphological sperm clusters we found evidence for the Constant Speed model, which predicts that power output is determined by the flagellum and so is proportional to flagellum length. Our results show the relationship between sperm morphology (size, width) and swimming speed is complex and that traditional models do not capture the biophysical interactions involved. Future work therefore needs to incorporate not only a better understanding of how sperm operate in the microfluid environment, but also the importance of fertilising environment, i.e., internal and external fertilisers. The microenvironment in which sperm operate is of critical importance in shaping the relationship between sperm length and form and sperm swimming speed.
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Gaffney EA, Ishimoto K, Walker BJ. Modelling Motility: The Mathematics of Spermatozoa. Front Cell Dev Biol 2021; 9:710825. [PMID: 34354994 PMCID: PMC8329702 DOI: 10.3389/fcell.2021.710825] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 06/25/2021] [Indexed: 11/23/2022] Open
Abstract
In one of the first examples of how mechanics can inform axonemal mechanism, Machin's study in the 1950s highlighted that observations of sperm motility cannot be explained by molecular motors in the cell membrane, but would instead require motors distributed along the flagellum. Ever since, mechanics and hydrodynamics have been recognised as important in explaining the dynamics, regulation, and guidance of sperm. More recently, the digitisation of sperm videomicroscopy, coupled with numerous modelling and methodological advances, has been bringing forth a new era of scientific discovery in this field. In this review, we survey these advances before highlighting the opportunities that have been generated for both recent research and the development of further open questions, in terms of the detailed characterisation of the sperm flagellum beat and its mechanics, together with the associated impact on cell behaviour. In particular, diverse examples are explored within this theme, ranging from how collective behaviours emerge from individual cell responses, including how these responses are impacted by the local microenvironment, to the integration of separate advances in the fields of flagellar analysis and flagellar mechanics.
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Affiliation(s)
- Eamonn A. Gaffney
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford, United Kingdom
| | - Kenta Ishimoto
- Research Institute for Mathematical Sciences, Kyoto University, Kyoto, Japan
| | - Benjamin J. Walker
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford, United Kingdom
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