Most, if not all, organisms age and die, but it is not clear whether aging and death are just unavoidable consequences of life or if these processes have some evolutionary advantage and are genetically controlled. This project is motivated by the question why and how the process of dying occurs in eukaryotic cells. To shed more light on this issue, using the advantages of the yeast experimental system, the project focuses on investigation of endogenous causes and deleterious molecular processes leading to cell death by studying all of 1100 genes required for yeast survival and growth.

In order to study the process of death caused by a controlled and known genetic perturbation, we have re-analyzed the complete collection of 1095 heterozygous essential gene mutants and characterized the (patho)physiological effects caused by the complete loss of each of the essential genes.

We used single cell microscopy analysis to obtain quantitative description of the effects of essential gene loss and observe the changes leading to death caused by endogenous factors.

Our results have raised new questions that we would like to answer:

• How can we define an essential gene?
• How do we define death of a unicellular organism?
• Is the cell dead when it cannot divide, when metabolism ceases or when the membrane ruptures?
• What causes a cell to stop dividing? What causes it to die?
• What causes the phenotypic differences in dying of isogenic cells in a controlled and stable environment?