Senescence Essay, Research Paper

Senescent cells cannot divide, but yet still remain metabolically active. In humans, the process of senescence may be the cause of aging that, over time, evolved to stop cancer (the uncontrolled growth of cells.) In plants, senescence starts from the moment they are harvested. It is the start of the terminal phase in the life cycle of the plant, the beginning of the end. As you can see, senescence has both positive and negative effects on living organisms.

Senescence is due to a gene called the lipase gene that is induced at the onset of senescence. The gene itself does not do the actual job of senescence. It encodes an enzyme that damages cellular membranes, which leads to a loss of metabolic function and to tissue spoilage. Cellular Membranes are very important to the life of a cell. At only one-millionth of a millimeter thick, it regulates what goes in and out of a cell.

The blue spots in each one of these pictures below represent the presence of senescent cells. The top left is young tissue is unaffected by senescence. The top right is sun burnt, which also lacks senescence. The bottom four are older cell tissues, which are evident by the senescent cells located inside them, represented by the blue spots.

Different types of trees are affected by senescence in different ways. Annual, biennial, and some types of perennials experience monocarpic senescence. In monocarpic senescence, the entire plant dies after seed formation. In herbaceous perennials, senescence of all above ground plants parts is very common feature. In order to produce new above ground structures for next season, an underground storage organ remains dormant until the next season and then produces the structures the next season. In temperate regions, woody plants show a senescence pattern typical of deciduous trees. All the leaves fall off in the fall because the meristems in the leaves become dormant. In the spring, leaves are replaced once the meristems come out of dormancy. Even in evergreen trees, which seem to never lose their leaves. They are continuously shed and produced in order of age.

Senescence has different effects on different things. Senescence in trees gets rid of their leaves during a certain time of the year, but the tree survives and eventually grows back the leaves. But senescence in picked fruit leads to the demise of the fruit, causing it to decompose. If the fruit is not eaten in time, the fruit will rot and go to waste. This results in a waste of billions of dollars a year. .

There is currently research done by a company called Senesco. They are currently developing a new technology that is designed to delay senescence in freshly harvested produce. This includes fruits, vegetables, and flowers. They discovered the lipase gene, the gene that destroys the cell. Their technology involves silencing this gene in the produce and flowers. Right now, they are using tomatoes, bananas, and cut carnation flowers for their experiments.

If Senesco, or any other company, can learn to stop or slow down senescence in plants, the results could be fabulous. Billions of dollars could be saved due to fruit not being wasted. And, by learning more about senescence itself, you could extend this research into delaying senescence in humans. Humans could live decades longer, coming closer to immortality. Although this is still far off, we are making progress. On October 4, 1999, Senesco delayed senescence in detached leaves of the Arabidopsis plant. The genetically altered leaves stayed green for ten days, whereas unaltered leaves started turning yellow within two or three days. After one week, chlorophyll levels were on an average of eight hundred percent higher in the altered leaves than the unaltered leaves. This has great effects on to fresh produce, such as lettuce, that has been harvested for the market.