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FRAGMENT FROM NATURE contemplates for this and next weekend, jumping genes (more correctly, transposons or mobile genetic elements) that are generated by viruses. These semi-autonomous simple strands of DNA including genes defy our ideas of life. Just strings of chemicals, they hop around host genome ecosystems as free-living parasites and symbionts, and also have had an enormous impact on evolution across taxa. These curious entities are truly extraordinary, and we still know so little about them. View in LinkedIn

THIS IS THE END of this long section on the biology of death. The subject is far from over, and the transition is purely artificial. I hope that this series of perspectives from a biological viewpoint, nested in observations and experiments across the living world has been insightful. View in LinkedIn

DNA REPEATS. “Interspersed repeats within genomes are created by transposition events accumulating over evolutionary time. Because interspersed repeats block gene conversion, they protect novel gene sequences from being overwritten by similar gene sequences and thereby facilitate the development of new genes. TEs may also have been co-opted by the vertebrate immune system as a means of producing antibody diversity. The V(D)J recombination system operates by a mechanism similar to that of some TEs.” (TE = transposable elements, jumping genes). https://en.m.wikipedia.org/wiki/Transposable_element View in LinkedIn

DEATH ANTAGONISTS. "Peter Thiel, the billionaire co-founder of PayPal, plans to live to be 120. Compared with some other tech billionaires, he doesn’t seem particularly ambitious. Dmitry Itskov, the “godfather” of the Russian Internet, says his goal is to live to 10,000; Larry Ellison, co-founder of Oracle, finds the notion of accepting mortality “incomprehensible,” and Sergey Brin, co-founder of Google, hopes to someday “cure death.” http://www.newsweek.com/2015/03/13/silicon-valley-trying-make-humans-immortal-and-finding-some-success-311402.html View in LinkedIn

JUMPING GENE FOSSILS. “Evolution often deactivates DNA transposons, leaving them as introns (inactive gene sequences). In vertebrate animal cells, nearly all 100,000+ DNA transposons per genome have genes that encode inactive transposase polypeptides. In humans, all Tc1-like transposons are inactive.” https://en.m.wikipedia.org/wiki/Transposable_element View in LinkedIn

BIRTH AND DEATH. “Beginnings are often difficult to pinpoint, particularly in life cycles, for life is continuous. Life does not tolerate a break (at most a transitory standstill in a stage of quiescence). Life is a continuing process that started some billions of years ago below the level of multicellularity and will end with the death of the last living being. Nevertheless, each individual life that is based on sexual reproduction has two discrete boundaries: fertilization and death.” https://lnkd.in/d6G9geU View in LinkedIn

PROTECTIONS AGAINST TEs. “Because excessive TE activity can damage exons, many organisms have acquired mechanisms to inhibit their activity. Bacteria may undergo high rates of gene deletion as part of a mechanism to remove TEs and viruses from their genomes, while eukaryotic organisms typically use RNA interference to inhibit TE activity. Nevertheless, some TEs generate large families often associated with speciation events.” (TE = transposable elements, jumping genes). https://en.m.wikipedia.org/wiki/Transposable_element View in LinkedIn

SELFISH DNA PARASITES. “While some TEs confer benefits on their hosts, most are regarded as selfish DNA parasites. In this way, they are similar to viruses. Various viruses and TEs also share features in their genome structures and biochemical abilities, leading to speculation that they share a common ancestor.” (TE = transposable elements, jumping genes). https://en.m.wikipedia.org/wiki/Transposable_element View in LinkedIn

TRANSPOSABLE ELEMENTS (TEs) “are found in almost all life forms, and the scientific community is still exploring their evolution and their effect on genome evolution. It is unclear whether TEs originated in the last universal common ancestor, arose independently multiple times, or arose once and then spread to other kingdoms by horizontal gene transfer.” (TE = transposable elements, jumping genes). https://en.m.wikipedia.org/wiki/Transposable_element View in LinkedIn

JUMPING GENES FROM VIRUSES. “Most viruses gave rise to just a few endogenous elements per host genome, but some have spawn massive genomic invasions.” https://www.sciencedirect.com/science/article/pii/S0959437X17301685 View in LinkedIn