We have been studying the yeast S.pombe microbe for a while now, using it as a model for living organisms for sixty years. You would think that we would have already found everything that there is to know about this beer cell. But turns out, this cell still has a lot to offer. Most cells reproduce by replicating itself. When a cell ages, it starts to develop defects and as a means of self preservation, it duplicates itself and separates a young, healthy cell, the daughter cell, while the original, old cell, the mother cell, with slowly die out. This is how most cells replicate themselves, asymmetrically. But the yeast cell is different.
It has been known for decades that the yeast cell replicates symmetrically, and it is not alone with that feature. But usually, the cells still leave a healthy cell and an aging cell. On the other hand, the yeast cell divides the damage between the two cells of the next generation. The researchers tested so by following a protein aggregation and the replication speed of the yeast cells. First, protein aggregation is a very common aging-related damaging condition. By following the traces of damage in each generation, the researching actually recorded that each pair of cells in a generation holds half the damage of the previous one. The second way they tested it was by recording the replication speed of the yeast cells. Usually, an aging cell takes longer and longer to replicate itself each generation. For example, if it takes a few seconds to replicate the first generation, it may take 20 seconds to divide the 75th generation. But the results of the speed of each generation’s replication were astounding – the number of generations did not affect the cell’s dividing speed, implying that these cells do not age.
Even though these cells do not age, it does not mean that they are immortal. Under ideal conditions, true, they can divide the damage evenly and spread it thin across the board. But under stressed conditions, the cells do leave a mother cell and a daughter, leading the mother cell to die off.
Perhaps the most important lesson about the discovery of this phenomenon is that there is always more than what meets the eye. Even though we’ve been learning about the yeast cell for decades, we still learnt about its non-aging feature these recent few years. This shows that we do not know everything there is to know about life. And that we should always keep a humble mind in the field of science, or in life for that matter.
http://www.astrobio.net/exclusive/5722/a-microbes-fountain-of-youth
