Biological benefits of collective swimming of sperm in a viscoelastic fluid

Abstract

Collective swimming is evident in the sperm of several mammalian species. In bull (Bos taurus) sperm, high viscoelasticity of the surrounding fluid induces the sperm to form dynamic clusters. Sperm within the clusters swim closely together and align in the same direction, yet the clusters are dynamic because individual sperm swim into and out of them over time. As the fluid in part of the mammalian female reproductive tract contains mucus and, consequently, is highly viscoelastic, this mechanistic clustering likely happens in vivo. Nevertheless, it has been unclear whether clustering could provide any biological benefit. Here, using a microfluidic in vitro model with viscoelastic fluid, we found that the collective swimming of bull sperm in dynamic clusters provides specific biological benefits. In static viscoelastic fluid, clustering allowed sperm to swim in a more progressive manner. When the fluid was made to flow in the range of 2.43–4.05 1/sec shear rate, clustering enhanced the ability of sperm to swim upstream. We also found that the swimming characteristics of sperm in our viscoelastic fluid could not be fully explained by the hydrodynamic model that has been developed for sperm swimming in a low-viscosity, Newtonian fluid. Overall, we found that clustered sperm swam more oriented with each other in the absence of flow, were able to swim upstream under intermediate flows, and better withstood a strong flow than individual sperm. Our results indicate that the clustering of sperm can be beneficial to sperm migrating against an opposing flow of viscoelastic fluid within the female reproductive tract.

ISG15-modification of the Arp2/3 complex restricts pathogen spread

“…We propose that ISGylation of Arp2/3 could be partly responsible for IFNAR-dependent facilitation of cell-to-cell spread through the establishment of straighter and stronger comet tails. Indeed, in other settings, there is precedent for group motility being more efficient that single cell motility in viscous fluids 56 . For Vaccinia virus, enhanced modification limits spread, as it does for Lm when properly regulated, but too much modification facilitates coordinated movement of connected daughter bacteria on two stabilized comet tails ushering the troupe into neighboring cells as a pack.…”

Continuous sheathless particle separation in viscoelastic fluids with different rheological properties

“…Microfluidic viscoelastic manipulation of particle has wide applications in the biomedical and clinical fields, and it has attracted extensive attentions in recent years (Manshadi et al 2020;Contreras-Naranjo et al 2017). For instance, viscoelastic fluids such as saliva (Schipper et al 2007;Bhat et al 2010), blood (Errilet 1969Baskurt and Meiselman 2003;Laura and Roel 2013), cytoplasm (Zhao et al 2023), mucus (Phuyal et al 2022), and are very ubiquitous in our body, and the separation of the microparticles such as the cells and bacteria in these vescoelatic fluids is of significance in the disease diagnosis, drug screening and clinical therapy (Mousavi et al 2022;Xiang and Ni 2022). Due to the promising potential of the viscoelastic fluids in the particle manipulation, various microfluidic techniques have been presented over the past few decades, which can be classified as the active and the passive techniques.…”

Effect of High Viscosity on Energy Metabolism and Kinematics of Spermatozoa from Three Mouse Species Incubated under Capacitating Conditions

“…In fluids of the female tract, this movement is thought to allow sperm cells to swim forward, improving progression in a viscoelastic medium [ 8 , 9 ]. Viscoelastic fluids may also promote collective sperm swimming [ 10 , 11 , 12 ]. The viscosity of fluids in the female reproductive tract is not uniform nor homogeneous; it varies among different tract regions and during the estrous cycle [ 13 , 14 , 15 ].…”