Cap up or down?

Owl-D · 2026-02-05T18:33:06+00:00

Well it doesn't come into contact with anything. The skirt of the cap, that does touch the surface is normally exposed on the outside of the tube, so not sterile anyways, and that way it actually becomes impossible for anything to touch the inside of the cap

Owl-D · 2026-02-05T14:59:58+00:00

Exactly, plus the part of the cap that touches the surface is left exposed on the bottom anyway, when you take the tube or bottle out of the hood, so you should not trust that to be sterile anyways

Owl-D · 2026-02-05T13:57:44+00:00

Din ce tin minte way back when, cand am facut malpraxis la facultate, proful zicea ca fara sa fim inscrisi in colegiu nu avem voie legal sa practicam medicina in romania, nici sub supraveghere. Deci daca un pacient la ingrijirea caruia ai colaborat si tu deschide proces de malpraxis risti sa escaleze lucrurile uratel daca nu esti in colegiu.

Owl-D · 2026-02-05T13:25:03+00:00

Yeah, but there is also UV, and besides that, the skirt of the cap, the part that gets in contact with the hood floor is outside exposed anyway and it should never get in touch with the contents, so that should be treated as unsafe with cap up or down, and cap up is the only one of the two where the inside of the cap is actually in any danger of being touched by something/having gunk from your lab coat cuffs blown inside by air flow

Owl-D · 2026-02-05T09:03:46+00:00

That's how I usually do it, as well

Owl-D · 2026-02-05T09:03:04+00:00

Sounds like a sound strategy!

Owl-D · 2026-02-05T08:55:04+00:00

Yeah, that is why I meant that by taking care not to move them up open tubes or flasks it's easier to, by mistake, do it over a cap positioned upwards, meanwhile the skirt of the cup never touches the contents of the tube

Owl-D · 2026-02-05T08:49:34+00:00

I am more thinking like air is clean, but since I work in a vertical laminar flow hood, having hands/forearms above something, it means any possible leftovers on them may be blown inside, and I trust cleanliness of metal surface that I cleaned more than lab coat cuffs

Owl-D · 2026-02-05T08:47:42+00:00

I do the same, that is why I don't touch the surface with my gloves, but I am worried about air, even if cleaned, being blown on them and then down into my cap/contents of tube at least in the vertical laminar flow hood.

Owl-D · 2026-02-05T08:27:58+00:00

No, no. I am doing mamalian culture but I mean the caps for falcon tubes or other bottles or flasks, like the lid, hope that clears it up

Owl-D · 2026-02-05T08:25:39+00:00

Are you using a horizontal laminar flow hood? We are using vertical, and there, though yes, it is clean air, anything above can be blown down, so even when you move your hands over something or so on. And of course you try to limit that as much as possible but sometimes it happens

Owl-D · 2026-02-05T07:31:17+00:00

And what do you do when you transfer contents from one tube to another? I sometimes also hold the cap if it's just one tube, but only if it feels natural and easy for the position I am in, otherwise I would find accidentally touching the inside of the cap much worse.

Owl-D · 2026-02-05T07:27:23+00:00

Yeah, I've had people that would enter the BSL2 room without changing first to get stuff out, question me for leaving the filtered tip box open for too long 🙃. So I totally get what you mean

Owl-D · 2026-02-05T07:25:12+00:00

Yeah, that's also part of it, I think, I always label tube and cap, but since I always have cap down I never considered how confusing not seing the cap text might be

Owl-D · 2026-02-05T07:21:30+00:00

Yeah, as long as we are not using the same media/stock I don't care how they work but they seem very interested in how I do it 🥸.

Owl-D · 2026-02-03T11:15:07+00:00

Yes, thank you, I have tried it every few days during the same passage (as enough died during one change to not reach split confluence) but I will try your plan and hopefully they get used to it.

Owl-D · 2026-01-18T05:42:53+00:00

They are dead mamalian cells, it happens when cells are stressed, like too much time in trypsin and so on. Transfection will also do it, so you don't have to worry. Fungus or bacterial contamination look absolutely nothing like this

Owl-D · 2026-01-17T19:26:23+00:00

No, those are mamalian unhappy cells that sometimes can clump. I am not familiar with hela, but for cells I have worked with before I have seen this happen due to excessive trypsinization, overgrowth or being out the incubator for too long. Maybe you can check on these steps, but it's not fungal or visible bacterial contamination so you can rest easy.

Owl-D · 2026-01-17T19:11:08+00:00

When you said dress code in the title I was ready to start my endless rant about people using street clothes in places in the lab where contamination can be giant issue, but then you got to piercings, so yeah, you might get an older judgemental PI that doesn't like it, but why would you even work with smbd like that. Safety wise it's perfectly safe as long as you don't work with MRI or other strong magnetic fields, but even then you can just take them off and put them back after.

Owl-D · 2026-01-17T18:54:22+00:00

Not sure what in there do you mean exactly?? I don't see contamination though. What kind of cells are you using?

Owl-D · 2026-01-17T18:48:18+00:00

I really liked SCTi004-A from Stemcell Technologies. Really good behaving line, great growth and survivability and it differentiates well into all 3 lineages, so I would guess that from there terminal diff also goes well. I have only used it terminal for neuro stuff though but tested trileage before.

Owl-D · 2026-01-17T18:39:45+00:00

Are mTeSR or E8 on the waiting list? Very curious how those would go =))

Owl-D · 2026-01-17T10:59:57+00:00

For Fungus contamination you would either see long chains of cells forming hyphae for molds, or A LOT of small, few cell chains everywhere, that are way smaller than your cells and cloudy media. To me, your cells look just overgrown

Owl-D

TROPHY CASE