PITP Day 1

First day of PITP at IAS. (Princeton looks very similar to Duke; IAS looks like Radcliffe; and the IAS housing reminds a lot of central campus in Durham).

Anyways. The most interesting discussion today stemmed from Arnold Levine’s talk on viruses, which quickly morphed into aging, telomere, evolution, cancer, etc.

Viruses: 2 modes of transmission–horizontal (person to person) or vertical (inherited). Equilibrium between virus and host. Host gains a bit more resistance and virus becomes less lethal. Example of rabbits brought to Australia and the virus used to reduce its population. Given more time, most of the viruses, including HIV, will be able to coexist peacefully with the host.

Aging: Hayflick’s experiments (1965). Measure generation time versus number of generations. Most human cells stop dividing after 50-70 generations. Cells seem to have internal counter for the # of generations, which was later discovered to be telomere. Most human cells lack telomerase, and after each generation, the telomere shortens. Without sufficient telomere, chromosomes are easily damaged/fused. Activating DNA repair mechanisms such as Rb (first line of defense, mortality 1) and p53 (second line of defense, mortality 2) that stalls the cell in G1, rather than go into S. SV40 and other viruses binds to P53 and Rb to deactive them, leading to immortal cells division. Immortal cells also express telomerase.

Length of telomere correlates with lifespan of animal. Feedback between metabolism and reproduction. Animals with later reproductive age tend to live longer due to metabolic changes. Deep connection with aging and cancer.

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