English: Genetic asymmetry of sigma F, spoIIAB and spoIIAA in B. subtilis. When approximately a third of the chromosome is moved into the forespore, sigma F and anti-anti-sigma factor spoIIAA are expressed in the forespore, promoting continued sporulation. The mother cell expresses high levels of anti-sigma factor spoIIAB, resulting in inhibition of sporulation. The mother cell’s chromosome is omitted for simplicity.