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Biological immortality

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Biological Immortality:
– State where mortality rate from senescence is stable or decreasing
– Can still die from other causes like injury, poison, disease
– Challenged by late-life mortality plateau concept
– Term also used for cells not subject to Hayflick limit
– Some species achieve biological immortality

Cell Lines:
– Term immortal used for cells not subject to Hayflick limit
– Immortalization first applied to cancer cells expressing telomerase
– Common immortalized cell lines include HeLa and Jurkat
– Embryonic stem cells and germ cells also described as immortal
– Immortal cancer cell lines can be induced through oncogenes

Organisms Achieving Biological Immortality:
– Bacteria and Some Yeast:
– Unicellular organisms age as they divide and die
– Symmetrically dividing bacteria and yeast can be biologically immortal
– Cell division restores cell to youthful state under ideal conditions
– Stem cells and gametes can be regarded as immortal
– Asymmetrically dividing cells age and die
– Hydra:
Genus of Cnidaria phylum capable of regeneration
– Hydras possess post-mitotic cells and continually divide
– Suggested to be biologically immortal as they do not undergo senescence
– Hydras did not show increased mortality with age in a study
– Reach maturity in 5 to 10 days and may live longer
– Jellyfish:
– Turritopsis dohrnii uses transdifferentiation to replenish cells
– Cycle of rejuvenation can repeat indefinitely
– Originated in the Caribbean sea and spread worldwide
– Molecular mechanisms involve DNA replication and stem cell renewal
– Similar cases include Laodicea undulata and Aurelia sp.1

Research Findings and Potential Applications:
– Quercetin in Cancer Cell Lines:
– Bulzomi’s study in 2012 showed pro-apoptotic effect of Quercetin in cancer cell lines.
– The effect of Quercetin required ERβ-dependent signals.
– This research highlights a potential anti-cancer property of Quercetin.
– Quercetin could be a promising avenue for cancer treatment.
– Understanding the mechanism of action of Quercetin is crucial for its therapeutic application.
– Glutamine as Energy Source:
– Research in 1978 by Reitzer et al. indicated glutamine, not sugar, as the major energy source for HeLa cells.
– This finding challenges the conventional belief about cell energy sources.
– Understanding the metabolic preferences of cancer cells is essential for targeted therapies.
– Glutamine metabolism could be a key target for cancer treatment strategies.
– Further studies are needed to explore the implications of glutamine metabolism in cancer.
Immortality of Stem Cells:
– University of Cologne’s 2018 study suggested the immortality of stem cells.
– Stem cells have unique properties that allow for self-renewal and longevity.
– Understanding stem cell immortality is crucial for regenerative medicine.
– Stem cells hold great potential for treating various diseases and injuries.
– Research on stem cell immortality opens new avenues for medical advancements.
– Naked Mole Rats and Aging:
– Studies in 2018 demonstrated that naked mole rats defy the biological law of aging.
– The risk of death in naked mole rats does not increase with age.
– Naked mole rats provide valuable insights into mechanisms of aging.
– Understanding the genetic basis of longevity in naked mole rats is essential.
– Research on naked mole rats may lead to novel anti-aging interventions.

Scientific Studies and Model Systems:
– Hydra as Model for Senescence:
– Hydra has been established as a long-lived model system for studying senescence.
– Research on Hydra provides insights into the lack of senescence in certain organisms.
– Understanding Hydra’s mortality patterns can shed light on aging processes.
– Hydra regeneration studies offer valuable information on longevity.
– Comparative genomics of mortal and immortal cnidarians reveal keys to rejuvenation.

Biological immortality (sometimes referred to as bio-indefinite mortality) is a state in which the rate of mortality from senescence is stable or decreasing, thus decoupling it from chronological age. Various unicellular and multicellular species, including some vertebrates, achieve this state either throughout their existence or after living long enough. A biologically immortal living being can still die from means other than senescence, such as through injury, poison, disease, predation, lack of available resources, or changes to environment.

This definition of immortality has been challenged in the Handbook of the Biology of Aging, because the increase in rate of mortality as a function of chronological age may be negligible at extremely old ages, an idea referred to as the late-life mortality plateau. The rate of mortality may cease to increase in old age, but in most cases that rate is typically very high.

The term is also used by biologists to describe cells that are not subject to the Hayflick limit on how many times they can divide.

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