Biology:Negligible senescence

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Short description: Organisms that do not exhibit evidence of biological aging
Some tortoises show negligible senescence.

Negligible senescence is a term coined by biogerontologist Caleb Finch to denote organisms that do not exhibit evidence of biological aging (senescence), such as measurable reductions in their reproductive capability, measurable functional decline, or rising death rates with age.[1] There are many species where scientists have seen no increase in mortality after maturity.[1] This may mean that the lifespan of the organism is so long that researchers' subjects have not yet lived up to the time when a measure of the species' longevity can be made. Turtles, for example, were once thought to lack senescence, but more extensive observations have found evidence of decreasing fitness with age.[2]

Study of negligibly senescent animals may provide clues that lead to better understanding of the aging process and influence theories of aging.[1][3] The phenomenon of negligible senescence in some animals is a traditional argument for attempting to achieve similar negligible senescence in humans by technological means.

In vertebrates

Some fish, such as some varieties of sturgeon and rougheye rockfish, and some tortoises and turtles[4] are thought to be negligibly senescent, although recent research on turtles has uncovered evidence of senescence in the wild.[2] The age of a captured fish specimen can be measured by examining growth patterns similar to tree rings on the otoliths (parts of motion-sensing organs).[5]

In 2018, naked mole-rats were identified as the first mammal to defy the Gompertz–Makeham law of mortality, and achieve negligible senescence. It has been speculated, however, that this may be simply a "time-stretching" effect primarily due to their very slow (and cold-blooded and hypoxic) metabolism.[6][7][8]

In plants

In plants, aspen trees are one example of biological immortality. Each individual tree can live for 40–150 years above ground, but the root system of the clonal colony is long-lived. In some cases, this is for thousands of years, sending up new trunks as the older trunks die off above ground. One such colony in Utah, given the nickname of "Pando", is estimated to be 80,000 years old, making it possibly the oldest living colony of aspens.[9]

The world's oldest known living non-clonal organism was the Methuselah tree of the species Pinus longaeva, the bristlecone pine, growing high in the White Mountains of Inyo County in eastern California , aged 4855–4856 years.[10] This record was superseded in 2012 by another Great Basin bristlecone pine located in the same region as Methuselah, and was estimated to be 5,062 years old. The tree was sampled by Edmund Schulman and dated by Tom Harlan.[11]

Ginkgo trees in China resist aging by extensive gene expression associated with adaptable defense mechanisms that collectively contribute to longevity.[12]

In bacteria

Among bacteria, individual organisms are vulnerable and can easily die, but on the level of the colony, bacteria can live indefinitely. The two daughter bacteria resulting from cell division of a parent bacterium can be regarded as unique individuals or as members of a biologically "immortal" colony.[13] The two daughter cells can be regarded as "rejuvenated" copies of the parent cell because damaged macromolecules have been split between the two cells and diluted.[14] See asexual reproduction.

Maximum life span

Some examples of maximum observed life span of animals thought to be negligibly senescent are:

Rougheye rockfish 205 years[15][16]
Aldabra giant tortoise 255 years
Lobsters 100+ years (presumed)[17]
Hydras Observed to be biologically immortal[18]
Planaria Observed to be biologically immortal[19]
Sea anemones 60–80 years (generally)[20]
Red sea urchin 200 years[21]
Freshwater pearl mussel 210–250 years[22][23]
Ocean quahog clam 507 years[24]

Cryptobiosis

Some rare organisms, such as tardigrades, usually have short lifespans, but are able to survive for thousands of years—and, perhaps, indefinitely—if they enter into the state of cryptobiosis, whereby their metabolism is reversibly suspended.[citation needed]

Negative senescence

There are also organisms[which?] that exhibit negative senescence,[25] whereby mortality chronologically decreases as the organism ages, for all or part of the life cycle, in disagreement with the Gompertz–Makeham law of mortality[26] (see also Late-life mortality deceleration). Furthermore, there are species that have been observed to regress to a larval state and regrow into adults multiple times, such as Turritopsis dohrnii.[27]

See also

References

  1. ↑ 1.0 1.1 1.2 "Negligible Senescence". Longevity, Senescence and the Genome. Chicago, IL: . University of Chicago Press. 1994. pp. 206–247. 
  2. ↑ 2.0 2.1 "Decades of field data reveal that turtles senesce in the wild". Proceedings of the National Academy of Sciences of the United States of America 113 (23): 6502–6507. June 2016. doi:10.1073/pnas.1600035113. PMID 27140634. Bibcode: 2016PNAS..113.6502W. 
  3. ↑ "Emerging area of aging research: long-lived animals with "negligible senescence"". Annals of the New York Academy of Sciences 1019 (1): 518–520. June 2004. doi:10.1196/annals.1297.096. PMID 15247078. Bibcode: 2004NYASA1019..518G. 
  4. ↑ "Escaping senescence: demographic data from the three-toed box turtle (Terrapene carolina triunguis)". Experimental Gerontology 36 (4–6): 829–832. April 2001. doi:10.1016/s0531-5565(00)00243-6. PMID 11295516. 
  5. ↑ "Confirmation on longevity in Sebastes diploproa (pisces Scorpaenidae) from 210Pb/226Ra measurements in otoliths". Marine Biology 71 (2): 209–215. 1882. doi:10.1007/bf00394632. 
  6. ↑ "Naked Mole-Rat mortality rates defy gompertzian laws by not increasing with age". eLife 7: e31157. January 2018. doi:10.7554/eLife.31157. PMID 29364116. 
  7. ↑ "Google's Calico Labs announces discovery of a "non-aging mammal."" (in en-US). LEAF. https://www.leafscience.org/non-aging-mammal/. 
  8. ↑ "Age is just a number". eLife 7: e34427. January 2018. doi:10.7554/eLife.34427. PMID 29364114. 
  9. ↑ Quaking Aspen by the Bryce Canyon National Park Service.
  10. ↑ "'Pinus longaeva". Gymnosperm Database. March 15, 2007. http://www.conifers.org/pi/Pinus_longaeva.php. 
  11. ↑ "OLDLIST, a database of old trees". Rocky Mountain Tree-Ring Research, Inc.. 2012. http://www.rmtrr.org/oldlist.htm. 
  12. ↑ "Multifeature analyses of vascular cambial cells reveal longevity mechanisms in old Ginkgo biloba trees". Proceedings of the National Academy of Sciences of the United States of America 117 (4): 2201–2210. January 2020. doi:10.1073/pnas.1916548117. PMID 31932448. Bibcode: 2020PNAS..117.2201W. 
  13. ↑ "A model for damage load and its implications for the evolution of bacterial aging". PLOS Genetics 6 (8): e1001076. August 2010. doi:10.1371/journal.pgen.1001076. PMID 20865171. 
  14. ↑ "Temporal dynamics of bacterial aging and rejuvenation". Current Biology 21 (21): 1813–1816. November 2011. doi:10.1016/j.cub.2011.09.018. PMID 22036179. 
  15. ↑ "Maximum Ages of Groundfishes in Waters off Alaska and British Columbia and Considerations of Age Determination". Alaska Fishery Research Bulletin 8: 1. 2001. 
  16. ↑ "Age determination and validation studies of marine fishes: do deep-dwellers live longer?". Experimental Gerontology 36 (4–6): 739–764. April 2001. doi:10.1016/s0531-5565(00)00239-4. PMID 11295512. 
  17. ↑ "140-year-old lobster's tale has a happy ending". Associated Press. January 10, 2009. http://www.nbcnews.com/id/28589278. 
  18. ↑ "Mortality patterns suggest lack of senescence in hydra". Experimental Gerontology 33 (3): 217–225. May 1998. doi:10.1016/s0531-5565(97)00113-7. PMID 9615920. 
  19. ↑ "Secrets from immortal worms: What can we learn about biological ageing from the planarian model system?". Seminars in Cell & Developmental Biology 70: 108–121. October 2017. doi:10.1016/j.semcdb.2017.08.028. PMID 28818620. https://ora.ox.ac.uk/objects/uuid:141ac384-2ac8-4507-898b-c3c59f03423e. 
  20. ↑ "Fact Files: Sea anemone". BBC Science and Nature. https://www.bbc.co.uk/nature/blueplanet/factfiles/jellies/sea_anemone_bg.shtml. 
  21. ↑ "Senescence and Longevity of Sea Urchins". Genes 11 (5): 573. May 2020. doi:10.3390/genes11050573. PMID 32443861. 
  22. ↑ "Life span variation of the freshwater pearlshell: a model species for testing longevity mechanisms in animals". Ambio XXIX (2): 102–105. 2000. doi:10.1579/0044-7447-29.2.102. 
  23. ↑ Зюганов В.В. (2004). "Арктические долгоживущие и южные короткоживущие моллюски жемчужницы как модель для изучения основ долголетия.". Успехи геронтол. 14: 21–31. 
  24. ↑ "The extreme longevity of Arctica islandica is associated with increased peroxidation resistance in mitochondrial membranes". Aging Cell 11 (5): 845–855. October 2012. doi:10.1111/j.1474-9726.2012.00847.x. PMID 22708840. 
  25. ↑ James W Vaupel 1 , Annette Baudisch, Martin Dölling, Deborah A Roach, Jutta Gampe. "The case for negative senescence". PubMed. https://pubmed.ncbi.nlm.nih.gov/15136009/. 
  26. ↑ "Evolution's greatest mistakes". New Scientist 195 (2616): 36–39. 2007. doi:10.1016/S0262-4079(07)62033-8. 
  27. ↑ "Cheating Death: The Immortal Life Cycle of Turritopsis". 8e.devbio.com. http://8e.devbio.com/preview_article.php?ch=2&id=6. 



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