Fig 1. M. fortuitum induces caspase dependent HKM apoptosis.

(A) TUNEL assay of uninfected, STS treated (positive control), M. fortuitum-infected with or without Z-VAD-FMK pre-treated HKM. The HKM were observed under confocal microscope (×40). (B) TEM analysis of uninfected and M. fortuitum-infected HKM. All the experiments were performed 24 h p.i. STS treated HKM were analysed 6 h post incubation. The images are representative of three independent experiments. N, nucleus; M, mitochondrion; FN, fragmented nucleus; B, bacteria; AB, apoptotic bodies. HKM, control head kidney macrophage; HKM+STS, HKM treated with STS; HKM+MF, HKM infected with M. fortuitum; HKM+MF+Z-VAD-FMK, HKM pre-treated with Z-VAD-FMK followed by M. fortuitum infection.