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LIFESPAN AND GENOMES. “Although numerous different pathways for aging have been proposed, it is striking that human premature aging syndromes are caused by defects in the maintenance of genomic stability, indicating that genomic integrity plays a key role in determining lifespan.” https://lnkd.in/dKvxxVz View in LinkedIn

EARLY PREDICTION. “The notion that repetitive copies of functional genes might govern, or trigger, the aging process had been suggested earlier by Medvedev. It was not until recently, however, that Olovnikov's remarkably insightful speculation was proven to be correct experimentally.” http://protein.bio.msu.ru/biokhimiya/contents/v62/full/62111380.html View in LinkedIn

REPEATS AND SENESCENCE. “Induction of non-coding RNA transcription from the repetitive Alu elements occurs during human stem cell aging and hinders efficient DNA repair causing entry into senescence.” http://journal.frontiersin.org/article/10.3389/fgene.2013.00136/full View in LinkedIn

“AT THE INTERSECTION of non-coding transcription, DNA repair, chromatin structure, and cellular senescence. Recent paradigm-setting studies are now revealing that non-coding RNAs, other than microRNAs, also play intriguing roles in the maintenance of chromatin structure, in the DNA damage response, and in adult human stem cell aging.” http://journal.frontiersin.org/article/10.3389/fgene.2013.00136/full View in LinkedIn

JUNK DNA, REPEATS, TRANSPOSONS AND VIRAL ELEMENTS. “Over evolutionary time, viruses actively exchange genetic material with their host cells. However, just because a non-coding RNA expressed by a virus exhibits hallmarks of a known class of host cell non-coding RNAs does not mean that it necessarily functions comparably. Viruses are extremely clever at altering the bits of host cell genome that they acquire to meet their own needs.” https://lnkd.in/dD7FjZ4 View in LinkedIn

CONSERVED REPEATS. “The telomeres in human cells consist of thousands of repeats of the sequence TTAGGG. This sequence is remarkably conserved from primitive organisms to humans. The sequence is found in all invertebrates and in some trypanosomes and slime molds.” http://protein.bio.msu.ru/biokhimiya/contents/v62/full/62111380.html View in LinkedIn

TELOMERE METRICS. “Harley et al. observed that the mean telomere length decreased by 2 to 3 kilobase pairs (kbp) during the serial passage of several strains of normal human diploid fibroblasts. The decrease was found to be progressive and averaged 50 base pairs for each population doubling. The telomere shortening seen in aging normal human fibroblasts also occurs in vivo in skin epidermal cells, peripheral blood leukocytes and colon mucosa epithelia.” http://protein.bio.msu.ru/biokhimiya/contents/v62/full/62111380.html View in LinkedIn

REPETITIVE DNA. “Telomeres are structures found at the ends of linear chromosomes and consist of repetitive DNA sequences. Telomeres apparently prevent recombination and allow the attachment of chromosome ends to the nuclear envelope.” http://protein.bio.msu.ru/biokhimiya/contents/v62/full/62111380.html View in LinkedIn

JUMPING GENES. “However, in response to a potential decay of the chromatin structure during aging, excess retrotransposon transcription prevents recruitment of cohesion and condensin, causing persistent DNA damage checkpoint activation and senescence.” http://journal.frontiersin.org/article/10.3389/fgene.2013.00136/full View in LinkedIn

SO ENDS this first of two weekends on plant alternation of generations. That such a complex system exists is in part due to the necessity of not increasing chromosome numbers during successive generations, as well as the cobbling together of available tools that were handy. Evolution is a zig zaggy chaotic process with many dead ends and mistakes. Nothing was purpose-built. View in LinkedIn