Great paper: a droplet #microfluidics assay to encapsulate single micron-sized algae to study long-term #behaviour.
https://elifesciences.org/articles/76519#fig4
by Bentley et al. gielenlab.com and @micromotility
A thread.
The locomotion of single-cells is characterised by a trio of motility macrostates (run, stop, tumble) with distinct transition probabilities that could be quantified by long-term imaging.
The motility is light-switchable, which was known, but the long-term imaging of single cells in light and dark revealed a cellular #memory: the light-altered behavioural state persisted after light off.
The authors also developed and tested a novel droplet-fusion assay to expose single cells in a controlled manner to chemicals. This could be a very elegant way to e.g., dissect #signalling mechanisms in the cells by #pharmacology.
Finally, here is the Editor's evaluation from @elife
This paper reports on the development of an impressive microfluidic platform for the study of motility, and motility transitions, exhibited by single algal cells in circular confinement. Building on previous work that showed a three-state motility repertoire for certain green algae, the present work uses extremely long time series and a variety of physical perturbations to show how those dynamics can be altered by environmental conditions. The work will be of interest to a wide range of scientists studying motility and non-equilibrium dynamics.
https://doi.org/10.7554/eLife.76519.sa0
@jekely This is so cool- so many possibiities for screening. I am now super-envious of your micro-organisms Gaspar & @micromotility! Congrats beautiful work Kirsty & co!
@micromotility @Mill_lab @jekely Nice work! I’ve always worried about edge effects with microbes under the scope (next to bubbles, for example). @micromotility, do you see effects of the interface of the droplet with the surrounding medium being different re: behavior?
@StearnsLab @Mill_lab @jekely
Thanks Tim! Great question! Yes there will always be some boundary effects, depending on whether it's a water-air interface or a solid boundary. In fact we show in the paper that the solid boundary is what tends to align the cell with the wall and makes it swim in circles in our set-up.
But in the end it depends on the question you're trying to answer... if you use a big enough droplet/trap then there's a good chance that behaviour will be largely unaffected. Secondly, consistency is key - so if you're looking at the effect on behaviour of some orthogonal parameter say light or chemicals, then as long as you keep the physical environment the same, it's a valid comparison!
@micromotility Cool science. Look forward to broader applications in other single-cell entities. 👍
@MingqingCai thanks very much for your interest! yes we hope this technology is useful for many different specimens!
#Chlamydomonas (2 #cilia) and #Pyramimonas (8 cilia) #algae were encapsulated into droplets by #microfluidics and imaged at high speed to characterise gait switching dynamics and the effect of light.