A. Hallén

In a surplus of nutrition baker´s yeast cells (Saccharomyces cerevisiae) propagate parthenogenetically by budding off daughter cells. Propagation of old mother cells leads to daughter lines with exaggerated signs of aging (Lansing effect). The age of the mother cell depends mainly on the number of cell divisions (maximum about 20 buds), but to a small degree also on the chronological age (metabolic time). It is proposed that the aging may be ascribed to an accumulation of insoluble cross-linked protein, formed as a side product of protein metabolism. Much protein is synthesized at mitosis, which may lead to a large deposit of insoluble protein. The insoluble protein of the mother cell is shared with the small daughter cell. The Lansing effect may be explained by the daughter cell obtaining a large amount of insoluble protein from an old mother cell. Multicellular organisms (e.g. Drosophila) that do not exhibit a Lansing effect may have developed strategies to avoid the insoluble protein accumulation at propagation. One such mechanism could be sexual propagation: the DNA-content of the haploid egg cell is doubled by the sperm without the protein synthesis involved in DNA-replication. However, a slow rate of insoluble protein synthesis unrelated to mitosis may remain, which may be a cause of aging in higher organisms, the age being related to the metabolic time

Keywords (Optional): 
Insoluble protein
Lansing effect