# aquaporin adventures by Alice L. '24

a livestream of my brain while working on my urop

**The Problem: **A reviewer went “You guys did things while assuming that cells exchange their water in the matter of milliseconds. Proof?”

**The Science Problem:** How fast does water get in/out of cells?

**1:31 am: **

I’m going to work on this for half an hour

Thought 1:Rate of water swooshing around = number of aquaporins * average rate of water through an aquaporin

**1:33 am: **

this paper tells me cells have “up to 10,000 [aquaporins] per square micron.”

which is kind of vague (what do you mean, up to? Can I get an actual distribution?) but I’m going to go with that 10,000 number

That’s half the terms I want. This is going well.

**1:37 am: **

these physicists have modeled some perfectly smooth aquaporins in a vacuum

but evidently that actually matches the experimental data okay

they do not give me any actual numbers that I want but maybe I could calculate it with the equations in this paper

but this sounds like a lot more math and I’m tired

**1:41 am: **

why don’t aquaporins have spec sheets?

**1:57 am:**

This is the sixth paper that tells me “aquaporins pump water” *without ever listing anything about the rate at which water flows through them*

if pump manufacturers just told me “yes this pump really *does* do the pumping” I would not buy these pumps

**2:10 am: **

I am going to apply to grad school with my entire personal statement being that I want my cells to have spec sheets.

**2:13 am: **

oh good somebody *has* measured this after all:

“AQP1

pf of 6 × 10−14cm3/s) were (in cm3/s × 10−14) 3.3 ± 0.2 (AQP2), 2.1 ± 0.3 (AQP3), 24 ± 0.6 (AQP4), 5.0 ± 0.4 (AQP5), and 0.25 ± 0.05 (MIP);”

**2:14 am: **

that’s a lot of subtypes

more subtypes than I expected

Revision: Thought 1.1:Rate of water swooshing around = sum(# of aquaporins(i)/total aquaporins * rate of water through aquaporins(i))

**2:19 am: **

here’s another paper that gives me one (1) rate for APQ1

but it disagrees with the other paper, by a lot

I would do a confidence interval but not when n = 2

**2:26 am: **

oh my god there are more

I’m going to listen to Grace and become a math major if someone gives me another aquaporin

**2:34 am:** and of course nobody will tell me what the relative proportions of aquaporins in a cell are

**2:41 am: **

today I learned that pinocytosis exists and maybe I need to factor that in now

**2:52 am: **

I have one job and I suck at it

and the bad thoughts have arrived so it’s bedtime

I am going to email my supervisor for a sanity check

maybe I am googling all the wrong terms and people *have* characterized these things

**5:41 am:** “order of magnitude estimate is enough” -supervisor

**1:33 pm:** oh thank god that makes my life a lot easier

**1:35 pm:**

me, to google:

*how many aquaporins in cell*

*aquaporin density*

*average aquaporin density*

*average number of aquaporins in cells*

*average surface area of a cell*

*surface area of cell*

google, to all my queries: aquaporins move water into the cell

**1:46 pm: **

I do some sketchy math and conclude that there are, at most, five (5) aquaporins in a cell

this feels wrong

**1:53 pm: **

I find a friendly local math major on my floor to check out my math

he looks stumped

**1:57 pm: **

we find a second friendly local math major on our floor to check out my math

he looks stumped

**1:59 pm: **

we find a friendly local nuclear major in the hopes that they can resolve our additive failures

**2:08 pm: **

math major #2 points out that I dropped an exponent

**2:24 pm:**

everything is somewhere in the millisecond range,

which is what we’d put on the paper anyways.

I’m kind of inclined to trust 5 and 6, at least in part because 6) is based off the perfectly smooth conical aquaporins in a vacuum and you should always trust physicists about their perfectly smooth spherical cows in vacuums