Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userFollowing in the footsteps of E. coli: sperm in microfluidic strictures
113
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We briefly describe the similarities of the experiments of sperm motion in microfluidic strictures by Zafeeani et al. in 2019 (Sci. Adv. 5, eaav21111, 2019) and those by Altshuler et al. in 2013 (Soft Matter 9, 1864, 2013). We shortly discuss the hydrodynamic elements justifying the strong resemblance between the two types of experiments, and suggest that other previous results in E. coli motion (Soft Matter 11, 6248, 2015) may shed further light on the understanding of sperm migration.
rate research
Read More
This paper describes my personal appreciation of some of Tini Veltmans great research achievements and how my own research career has followed the pathways he opened. Among the topics where he has been the most influential have been the pursuit and study of the Higgs boson and the calculation of radiative corrections that enabled the masses of the top quark and the Higgs boson to be predicted ahead of their discoveries. The search for physics beyond the Standard Model may require a complementary approach, such as the search for non-renormalizable interactions via the Standard Model Effective Field Theory.
The swimming properties of an E. coli-type model bacterium are investigated by mesoscale hy- drodynamic simulations, combining molecular dynamics simulations of the bacterium with the multiparticle particle collision dynamics method for the embedding fluid. The bacterium is com- posed of a spherocylindrical body with attached helical flagella, built up from discrete particles for an efficient coupling with the fluid. We measure the hydrodynamic friction coefficients of the bacterium and find quantitative agreement with experimental results of swimming E. coli. The flow field of the bacterium shows a force-dipole-like pattern in the swimming plane and two vor- tices perpendicular to its swimming direction arising from counterrotation of the cell body and the flagella. By comparison with the flow field of a force dipole and rotlet dipole, we extract the force- dipole and rotlet-dipole strengths for the bacterium and find that counterrotation of the cell body and the flagella is essential for describing the near-field hydrodynamics of the bacterium.
Investigating sperm locomotion in the presence of an external fluid flow and geometries simulating the female reproductive tract can lead to a better understanding of sperm motion during the fertilization process. In this study, using a microfluidic device featuring a stricture that simulates the biophysical properties of narrow junctions inside the female reproductive tract, we observed the gate-like role the stricture plays to prevent sperm featuring motility below a certain threshold from advancing towards the fertilization site. At the same time, all sperm slower than the threshold motility accumulate before the stricture and swim in a butterfly-shaped path between the channel walls which maintains the chance of penetrating the stricture and thus advancing towards the egg. Interestingly, the accumulation of sperm before the stricture occurs in a hierarchical manner so that sperm with higher velocities remain closer to each other and as the sperm velocity drops, they spread further apart.
We present a mathematical model of glucose-lactose diauxic growth in Escherichia coli including both the postive and negative regulation mechanisms of the lactose operon as well as the inducer exclusion. To validate this model, we first calculated the time evolution of beta-galactosidase for only the lactose nutrient and compared the numerical results with experimental data. Second, we compared the calculated cell biomass of the glucose-lactose diauxic growth with the experimental optical density of the diauxic growth for a particular E. coli MG 1655. For both cases, the numerical calculations from this model are in good agreement with these two experiments data. The diauxic growth pattern of a wild type E. coli was also investigated.
Many self-propelled microorganisms are attracted to surfaces. This makes their dynamics in restricted geometries very different from that observed in the bulk. Swimming along walls is beneficial for directing and sorting cells, but may be detrimental if homogeneous populations are desired, such as in counting microchambers. In this work, we characterize the motion of human sperm cells $60 mu m$ long, strongly confined to $25 mu m$ shallow chambers. We investigate the nature of the cell trajectories between the confining surfaces and their accumulation near the borders. Observed cell trajectories are composed of a succession of quasi-circular and quasi-linear segments. This suggests that the cells follow a path of intermittent trappings near the top and bottom surfaces separated by stretches of quasi-free motion in between the two surfaces, as confirmed by depth resolved confocal microscopy studies. We show that the introduction of artificial petal-shaped corrugation in the lateral boundaries removes the tendency of cells to accumulate near the borders, an effect which we hypothesize may be valuable for microfluidic applications in biomedicine.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
