Polarity, Asymmetry and Aging:Are there Yayatis among Bacteria?

Bacteria have been shown to age. In an exponentially growing population some cells progressively slow down and stop dividing. This is thought to be due to asymmetric damage segregation in which old pole cells retain damaged components and the new pole cells receive newly synthesized components. Polarity implies functional asymmetry with a predefined direction with or without morphological difference. Cellular polarity and division asymmetry are common to yeast, bacteria and stem cells of multi-cell organisms. A number of processes in bacteria, including formation of endospores, flagella, stalks or buds show clear polar biases.