Editorial the immortality of the germ line: the neverending story

This is a short review concerning the problem of the germ line «immortality» which was already formulated by A. Weismann at the end of the 19th century. Over the following years, it attracted the attention of many gerontologists who tried to understand the mechanisms of infinite transfer of genetic information from generation to generation with the help of germ cells, which, in contrast to somatic cells, avoid aging in this way. However, it remained unclear how the germ cells of women, which are in fact a population of non-dividing cells (it is similar to stationary phase aging non-subcultured cell culture), provide the mentioned immortality of the germ line. The distinguished Russian gerontologist Zh.A. Medvedev, who passed away recently, published in 1981 his brilliant work «On the immortality of the germline: genetic and biochemical mechanisms. A review», the main points of which are relevant up to today. His paper just discusses the possible mechanisms of such «immortality». They are analyzed in detail in the current article and boil down mainly to the existence of a number of barriers that, in most cases, do not allow progeny to emerge from «old» germ cells (although certain «rejuvenating» processes in the gametes still go). Therefore, children are being «born young.» Some alternative approaches to explanation of the immortality of the germ line are also considered. Special attention is paid to «parental age effect» and the role of eggs and sperm cells in the phenomenon.

1. Хохлов А.Н. Пролиферация и старение // Итоги науки и техники ВИНИТИ АН СССР, серия «Общие проблемы физико-химической биологии», том 9. М.: ВИНИТИ, 1988. 176 с.

2. Khokhlov A.N. Cell proliferation restriction: is it the primary cause of aging? // Ann. N.Y. Acad. Sci. 1998. Vol. 854. P. 519.

3. Khokhlov A.N. From Carrel to Hayflick and back, or what we got from the 100-year cytogerontological studies // Biophysics. 2010. Vol. 55. N 5. P. 859-864.

4. Khokhlov A.N., Klebanov A.A., Morgunova G.V. Does aging have a purpose? // Moscow Univ. Biol. Sci. Bull. 2017. Vol. 72. N 4. P. 222-224.

5. Khokhlov A.N., Morgunova G.V. Testing of geroprotectors in experiments on cell cultures: pros and cons // Anti-aging drugs: From basic research to clinical practice / Ed. A.M. Vaiserman. Royal Society of Chemistry, 2017. P. 53-74.

6. Weismann A. Die Kontinuitat des Keimplasmas als Grundlage einer Theorie der Vererbung. Jena: G. Fisher, 1885. 112 pp.

7. Weismann A. Das Keimplasma. Eine Theorie der Vererbung. Jena: G. Fisher, 1892. 628 p.

8. Nussbaum M. Zur Differenzierung des Geschlechts im Tierreich // Arch. Mikr. Anat. 1880. Vol. 18. P. 1-121.

9. Khokhlov A.N. On the immortal hydra. Again // Moscow Univ. Biol. Sci. Bull. 2014. Vol. 69. N 4. P. 153-157.

10. Medvedev Zh.A. On the immortality of the germ line: genetic and biochemical mechanisms. A review // Mech. Ageing Dev. 1981. Vol. 17. N. 4. P. 331-359.

11. Khokhlov A.N., Klebanov A.A., Morgunova G.V. Anti-aging drug discovery in experimental gerontological studies: from organism to cell and back / Aging: exploring a complex phenomenon. Ed. Sh.I. Ahmad. Boca Raton: Taylor & Francis, 2018. P. 577-595.

12. Bernstein C. Why are babies young? Meiosis may prevent aging of the germ line // Perspect. Biol. Med. 1979. Vol. 22. N 4. P. 539-544.

13. Khokhlov A.N. What will happen to molecular and cellular biomarkers of aging in case its program is canceled (provided such a program does exist)? // Adv. Gerontol. 2014. Vol. 4. N 2. P. 150-154.

14. Khokhlov A.N. Impairment of regeneration in aging: Appropriateness or stochastics? // Biogerontology. 2013. Vol. 14. N 6. P. 703-708.

15. Khokhlov A.N. Stationary cell cultures as a tool for gerontological studies // Ann. N.Y. Acad. Sci. 1992. Vol. 663. P. 475-476.

16. Morgunova G.V., Klebanov A.A., Khokhlov A.N. Interpretation of data about the impact of biologically active compounds on viability of cultured cells of various origin from a gerontological point of view // Moscow Univ. Biol. Sci. Bull. 2016. Vol. 71. N 2. P. 67-70.

17. Morgunova G.V., Klebanov A.A., Khokhlov A.N. Some remarks on the relationship between autophagy, cell aging, and cell proliferation restriction // Moscow Univ. Biol. Sci. Bull. 2016. Vol. 71. N 4. P. 207-211.

18. Morgunova G.V., Klebanov A.A., Marotta F, Khokhlov A.N. Culture medium pH and stationary phase/chronological aging of different cells // Moscow Univ. Biol. Sci. Bull. 2017. Vol. 72. N 2. P. 47-51.

19. Khokhlov A.N. Cell kinetic approaches to the search for anti-aging drugs: Thirty years after // Moscow Univ. Biol. Sci. Bull. 2018. Vol. 73. N 4. P. 185-190.

20. Khokhlov A.N., Klebanov A.A., Morgunova G.V. On choosing control objects in experimental gerontological research // Moscow Univ. Biol. Sci. Bull. 2018. Vol. 73. N 2. P. 59-62.

21. Morgunova G.V., Klebanov A.A. Impairment of the viability of transformed Chinese hamster cells in a nonsubcultured culture under the influence of exogenous oxidized guanoside is manifested only in the stationary phase of growth // Moscow Univ. Biol. Sci. Bull. 2018. Vol. 73. N 3. P. 124-129.

22. Baker T.G. Primordial germ cells // Reproduction in mammals. Book I: Germ cells and fertilization. Eds. C.R. Austin and R.V. Short. N.Y.: Cambridge Univ. Press, 1972. P. 1—13.

23. Gilbert S.F. Developmental biology, seventh edition. Sunderland: Sinauer Associates, Inc., 2003. 750 pp.

24. Khokhlov A.N. Cytogerontology at the beginning of the third millennium: From «correlative» to «gist» models // Russ. J. Dev. Biol. 2003. Vol. 34. N 5. P. 321-326.

25. Khokhlov A.N. Does aging need its own program, or is the program of development quite sufficient for it? Stationary cell cultures as a tool to search for anti-aging factors // Curr. Aging Sci. 2013. Vol. 6. N 1. P. 14-20.

26. Henderson S.A., Edwards R.G. Chiasma frequency and maternal age in mammals // Nature. 1968. Vol. 218. N 5136. P. 22-28.

27. Karnaukhov A.V., Karnaukhova E. V. Informational hypothesis of aging: How does the germ line “avoid” aging? // Biophysics. 2009. Vol. 54. N 4. P. 531-535.

28. Olovnikov A.M. Chronographic theory of development, aging, and origin of cancer: Role of chronomeres and printomeres // Curr. Aging Sci. 2015. Vol. 8. N 1. P. 76-88.

29. Khokhlov A.N. Which aging in yeast is «true»? // Moscow Univ. Biol. Sci. Bull. 2016. Vol. 71. N 1. P. 11-13.