A Swiss Research team from ISREC and the Univerity of Pavia have recently (4/8/07) discovered that Telomeres (1), once understood to be ‘Junk DNA’ with no coding processes and a function that is purely structural, actually have other roles and activities.
Telomeres are the ends of chromosomes in eucaryotes, derived from the Greek ‘Telos’ and ‘Mere’ which literally translates as ‘End Part’. Telomeres do not appear in procaryotes or mitochondrial DNA as they consist of rings and hence, have no ‘end’ as such. Telomeres are DNA which consists of the sequence ‘TTAGGG'(2) in vertebrates, repeated until the physical end of the strand.
Scientists had believed since the 1970’s (3) that telomeres where used chiefly as counting mechanisms for cells and as structural support. These two roles are complementary as the cells require both a structural anchor while they are copied and a mechanism to determine how many times a cell has mitosed. Telomeres serve as a padding and gradually get shorter after the Anaphase in cell mitosis(3). This is to protect the valuable code contain in the DNA and as such many several thousands bases make up the telomeres. Once the limit of the telomeres is reached, the cell dies.
What the Swiss researchers have discovered is that these ‘dead’ ends, do actually take part of reproduction, in that they form RNA copies of themselves(4), which can be used to hypothesize as to why some cells refuse to accept their ‘shelf-life’ as it would seem and become cancerous. It is believed that this new discovery could be applied in the treatment of telomere related tumors.
1 - New Scientist: Chromosome caps may explain cell immortality
2 - Medicine Net; Definition of 'telomere'
3 - Answers.com : Telomeres; Telomere shortening in a long-lived marine bird: Cross-sectional analysis and test of an aging tool
4 - Sciencemag.org : Telomeric Repeat–Containing RNA and RNA Surveillance Factors at Mammalian Chromosome Ends