Molecular mechanism of the adder in bacterial size control
In plain words
Bacteria such as E. coli add a fixed amount of volume between birth and division, whatever size they were born at, which keeps the population at a stable size. Which molecular process enforces this rule is disputed.
Precise statement
In E. coli and B. subtilis the added volume between birth and division is independent of birth volume (Taheri-Araghi and co-workers, 2015). Decide between division control by threshold accumulation of a division protein synthesized in proportion to growth, such as FtsZ (Si and co-workers, 2019), and control by DNA replication initiation through a double adder (Witz, van Nimwegen and Julou, 2019), by predicting the full set of correlations among birth size, initiation size, division size and timing and their response to titrated expression of FtsZ and DnaA.
What would settle it
Single-cell lineage measurements under titrated FtsZ and DnaA expression whose correlation structure matches one model and excludes the other.
Status in the literature
Unverified note
Si and co-workers (Current Biology 2019, doi 10.1016/j.cub.2019.04.062) and Witz and co-workers (eLife 2019, doi 10.7554/eLife.48063) support different mechanisms; 2024 to 2026 status not re-checked by this survey.