FIG 6.

TEM and SR-SIM reveal severe septal abnormalities in sle1 mutant cells exposed to oxacillin. TEM and SR-SIM images of JE2 wild-type (A), JE2clpX_I265E (B), or JE2sle1 (C) strains grown in the absence of oxacillin (left panels) or after exposure to 1.25 μg ml⁻¹ oxacillin for 20 min (right panels). The images show the characteristic morphological changes induced by oxacillin as determined from at least two biological replicates. In JE2sle1 cells, oxacillin induces severe septal abnormalities and cell lysis, including thickened septum devoid of the electron-dense midzone (i), a septal fragment that in TEM images appears not to be attached to the peripheral wall (ii), septum protruding asymmetrically inward (iii), and a lysed cell (iv). Scale bars: TEM, 0.2 μm; SR-SIM, 0.5 μm.