Petra Levin

@[email protected]
206 Followers
243 Following
32 Posts
Microbiologist, mom, runner with delusions of completing a marathon. This Week in Microbiology co-host (https://www.microbe.tv/twim/). Website: https://sites.wustl.edu/levinlab/. Views my own.
Petra LevinApr 21, 2023

🔬🔬Microbiology PIs looking for a great way to show your students you care?

Nominate them for the TOP prize in prokaryotic molecular biology, the Nat L. Sternberg Award!

Nominations due May 1, 2023

https://conferences.union.wisc.edu/phages/awards-prizes/sterenberg-thesis-prize/

Sternberg Thesis Prize | Molecular Genetics of Bacteria and Phages Meeting

Show threadPetra LevinJan 7, 2023
And 3. Perhaps most importantly, even under “steady state” conditions” there is a large (3X ish) variation in single cell growth rate (i.e. not really steady-state) and a wide variation in multifork replication frequency. I.e. all cells are not the same.
Show threadPetra LevinJan 7, 2023

Based on population data Cooper and Helmstetter postulated that there are 2 growth regimes: slow & fast.

In the slow regime, the initiation & elongation phases of DNA replication & division are pegged to mass doubling time (MDT).

In the fast regime, C-period, the time required to complete a round of replication becomes fixed. This is a problem when C-period > MDT. To deal with this, C & H proposed cells start new rounds of replication prior to finishing old ones—>multifork replication.

Show threadPetra LevinJan 7, 2023
Population-based data washes out all this variation, which leads to models that do not reflect what is happing inside individual cells. This is obviously a problem if you are a molecular biologist whose job description is to try and understand what is happening inside cells.
Show threadPetra LevinJan 7, 2023
Rather than double in mass each generation, bacteria add the same amount of material. This phenomenon, known as adder, ensure that population size is maintained despite a high degree of stochasticity in size at birth (From Taheri et al, 2015)