LostFerret

LostFerret t1_ishybgl wrote

Reply to comment by SaintUlvemann in TIL: Sperms were thought to move by wiggling their tails side-to-side, like eels, for 350 years. But research shows that they roll as they move forward like a spinning top. by vect77

Ah, sorry, didn't realize that second paper was paywalled. Fhe first paper focuses on form generating asmety in cilliated swimmers, the second paper extends that to asymmetry in either form or force and classifies swimmers as pushing (posterior flagellum) or pulling (anterior flagellum).

Both papers present the idea that any asymmetry in the swimmingof unicellular swimmers will produce circular or irregular patterns unless balanced by regular rotation linked to those forces. This is further explored in that more recent paper.

We expect EVERY eukaryotic, unicellular swimmer capable of helical / straight lines to follow this behavior, its just the way that the physics of swimming work at low reynolds numbers. Honestly, it would be way more surprising if we found a unicellular swimmer that did NOT spin while swimming.

So while sperm bodies may be somewhat symmetrical (im not sure if this is actually the case? There are a ton of weird fuckin sperm out there..google ostracod sperm for a trip..i dont know the range of human sperm morphology), the force they are producing is definitely not. To counter this asymmetry they rotate the entire cell, not just the head. This creates a helical procession that lets the sperm swim relatively straight.

We've known that euk. Flagellum don't beat in a single plane for a while, so im surprised we hadn't picked up on the asymmetrical beat pattern of human sperm until now. The imaging is pretty cool here though, I'd love to get my cells on that scope though they're tiny compared to sperm.

The title of this post is hot garbage tho, i was so happy to see you post about the prot/euk flagellar difference.

I think this is just a case of silo'd science. I only found those two papers because im working with weird non-animal cells and the modelers im collaborating with had some questions we couldnt answer so i did a very thorough literature search. They do bacterial motility modeling and hadn't seen the paper despite it being directly related to one of their theses. Human research, especially sperm research, is pretty isolated so it's likely the researchers who published the new paper didnt know it exists.

10

LostFerret t1_isgypue wrote

Reply to comment by SaintUlvemann in TIL: Sperms were thought to move by wiggling their tails side-to-side, like eels, for 350 years. But research shows that they roll as they move forward like a spinning top. by vect77

Rotary motion is not a surprise. See paper from 1901 https://www.jstor.org/stable/pdf/2453750.pdf

More work building on this with self powered nanomachines https://journals.aps.org/rmp/pdf/10.1103/RevModPhys.88.045006

24