Kay writes:

Dear TWIV and TWIM team,

I listen to both shows since episode 1 and am still on board, so you can safely assume that I like what you do very much!

I noticed on several occasions (including last week’s TWIM) that you think the word “prokaryote” has to be avoided at any cost. I must say that I totally disagree on this, although I usually agree happily to most of your other ‘scientific pedantries’.

In my humble option, the term that should be avoided is “Prokaryota”, together with everything else that would suggests that Prokaryotes constitute a monophyletic taxon – which they clearly don’t. However, the term “prokaryote” itself is not considered a taxon and is extremely useful. Many aspects of cellular life are different in Eukaryotes and non-eukaryotes, and “Prokaryote” as a synonym of “Non-Eukaryote” is less unwieldy and should be given preference.

The avoidance of the word “Prokaryote” makes even less sense in a context where people use expressions like “arboviruses” and “dependiviruses”  – two other terms that are widely considered acceptable although these groups are polyphlyetic and there are no taxa called “arboviridae” or “dependivirales” or similar.

Not every biological expression that summarizes a group of organisms has to be a monophyletic clade. Think about “apes” (paraphyletic), “insectivores” (polyphyletic), zooplankton (polyphyletic) and many other terms that are useful to describe groups of species by a common property without relying on taxonomy. Prokaryotes is just one of these terms and should not be banned – if we make clear that it is not a backed by taxonomy.

Best Wishes,



Kay Hofmann                         

Institute for Genetics

University of Cologne

Sophia writes:

Dear twim team

thank you for your input on coronaviruses and info on masks. I do have some questions about what Dr. Schmidt said about surgical masks. I didn’t get what he said. Could you please explain why an N95 is good to prevent TB but doesn’t make a difference for viruses? Is it because if viruses are transmitted through aerosols they will still go through the mask? I know TB microbes remain suspended in the air for a while. But the N95 mask does not allow penetration? the microbes are too big to penetrate but small enough to remain suspended in the air? is that correct? Also, a WHO lady answering quesitons from the audience did agree with Dr. Schmidt’s suspicion that the virus is not airborne but transmits through droplets. Great! why is it necessary then to wear a mask walking down the empty streets of Wuhan or why not allowed to walk around anyway? Also, PUblic Health England seems to think otherwise listing the virus as airborne: https://www.gov.uk/guidance/high-consequence-infectious-diseases-hcid?fbclid=IwAR2fCdZHyVQVIl_dmYLE7oDbavTKNfKMeGs3-s44_7_1UDsWNolm3g1utvI#classification-of-hcids

Here is the interview from WHO for your reference:


Also, the Greek CDC advised about “close contact” with infected patients defining it as “spending at least 15 mins with the infected person in less than 1m distance or more than 2 hours in a room/closed space”. I assume they get their info from WHO but these instructions wouldn’t agree with an aerosolized pathogen? Do I make any sense ? sorry, I got really confused

Speaking of the WHO, they recommend hand hygiene lasting 40-60” for hand washing and 20-30” for alcohol rubbing. Isn’t this way too LONG for a nurse, I mean do nurses actually have time for this? or is this the reason why they wear gloves? how often should you hand sanitize if wearing gloves? 

Wishing you a great twim year and all the best


Will offer explanation‚Ķ. 

ps I think of Elio too when I read about mushrooms!