Programmed cell death

This paper reviews data on programmed cell death (apoptosis) in animals and plants. Necrosis is a pathological scenario of cell death, which entails a n inflammatory response in animal tissues. Apoptosis results in the disinte gration of animal/plant cells into membrane vesicles enclosing the intracel lular content, which are thereupon engulfed by adjacent or specialized cell s (phagocytes) in animals, plants lack such specialized cells, and plant ce ll walls prevent phagocytosis. The paper considers the main molecular mecha nisms of apoptosis in animals and the pathways of activation of caspases, e volutionarily conserved cysteine proteases. A self-contained section concer ns itself with the process of programmed cell death (PCD) in microorganisms including: 1) cell death in the myxomycete Dictyostelium discoideum and th e parasitic flagellate Trypanosoma cruzi; 2) PCD in genetically manipulated yeast expressing the proapoptotic Bax and Bak proteins; 3) the death of a part of a prokaryotic cell population upon the depletion of nutrient resour ces or under stress; 4) the elimination of cells after a loss of a plasmid encoding a stable cytotoxic agent in combination with an unstable antidote; and 5) PCD in phage-infected bacterial cells.