SUMMARY. The results of the analysis of the nucleus and nucleoli features in the seeds of Pinus brutia var. stankewiczii Sukacz under conditions of the marginal part of the distribution and recreational load area are presented. The polymorphism in the number of nucleoli and their size in the cells of seedlings from the south-eastern coast of the Crimea was found between P. brutia var. stankewiczii populations. An increase in the average area of nucleoli in the nucleus and a decrease in the nucleus-nucleolus ratio were observed for the population under the recreational pressure, which indicates higher functional activity of the genetic apparatus of cells in response to adverse conditions. The change of nucleus-nucleolus parameters depending on the level of heterozygosity of mother trees was shown. The plants with low heterozygosity tended to have larger nucleoli. The identified trends indicate the complex nature of changes in the cells of the seed progeny of P. brutia var. stankewiczii.
Keywords: nucleus, nucleolus, level of heterozygosity, Pinus brutia var. stankewiczii Sukacz.

Full text and supplemented materials
References
Altukhov, Y.P. and Moskaleichik, F.F., Allozyme heterozygosity, metabolic rate, sexual maturation rate, and longevity, Dokl. Biol. Sci., 2006, vol. 410, pp. 416–420. https://doi.org/10.1134/S0012496606050218
Andersen, J.S., Lam, Y.W., Leung, A.K., et al., Nucleolar proteome dynamics, Nature, 2005, vol. 433, pp. 77–83. https://doi.org/10.1038/nature03207
Boulon, S., Westman, B.J., Hutten, S., et al., The nucleolus under stress, Mol. Cell, 2010, vol. 40, no. 2, pp. 216–227. https://doi.org/10.1016/j.molcel.2010.09.024
Britton-Davidian, J., Cazaux, B., and Catalan, J., Chromosomal dynamics of nucleolar organizer regions (NORs) in the house mouse: micro-evolutionary insights, Heredity, 2012, vol. 108, pp. 68–74. https://doi.org/10.1038/hdy.2011.105
Cantwell, H. and Nurse, P., Unravelling nuclear size control, Curr. Genet., 2019, vol. 65, pp. 1281–1285. https://doi.org/10.1007/s00294-019-00999-3
Chelomina, G.N., Rozhkovan, K.V., Burundukova, O.L., et al., Age-dependent and tissue-specific alterations in the rDNA clusters of the Panax ginseng C. A. Meyer cultivated cell lines, Biomolecules, 2020, vol. 10, no. 10, art. ID 1410. https://doi.org/10.3390/biom10101410
Derenzini, M., Pasquinelli, G., O’Donohue, M.-F., et al., Structural and functional organization of ribosomal genes within the mammalian cell nucleolus, J. Histochem. Cytochem., 2006, vol. 54, no. 2, pp. 131–145. https://doi.org/10.1369/jhc.5R6780.2005
De Storme, N. and Mason, A., Plant speciation through chromosome instability and ploidy change: Cellular mechanisms, molecular factors and evolutionary relevance, Curr. Plant Biol., 2014, vol. 1, pp. 10–33. https://doi.org/10.1016/j.cpb.2014.09.002
Hein, N., Sanij, E., and Quin, J., et al., The nucleolus and ribosomal genes in aging and senescence, in Senescence, London: IntechOpen, 2012, pp. 171–208. https://doi.org/10.5772/34581
Book
Khrolenko, Yu.A., Burundukova, O.L., Lauve, L.S., et al., Characterization of the variability of nucleoli in the cells of Panax ginseng Meyer in vivo and in vitro, J. Ginseng Res., 2012, vol. 36, no. 3, vol. 322–326. https://doi.org/10.5142/jgr.2012.36.3.322
Korshikov, I.I. and Gorlova, E.M., Genetic structure, subdivision, and differentiation in stankewiczii pine (Pinus stankewiczii (Sukacz.) Fomin) populations from mountainous Crimea, Russ. J. Genet., 2006, vol. 42, no. 6, pp. 672–680. https://doi.org/10.1134/S1022795406060135
Korshikov, I.I., Tkacheva, Yu.A., and Privalikhin, S.N., Cytogenetic abnormalities in Norway spruce (Picea abies (L.) Karst.) seedlings from natural populations and an introduction plantation, Cytol. Genet., 2012, vol. 46, pp. 280–284. https://doi.org/10.3103/S0095452712050064
Korshikov, I.I., Lapteva, Ye.V., and Tkachova, Yu.A., Variation in quantitative-dimensional characteristics of nucleoli and nuclei in seed cells of Pinus pallasiana D. Don (protected and human-disturbed areas in the steppe zone of Ukraine), Ukr. Bot. J., 2013, vol. 70, no. 6, pp. 805–812.
Korshikov, I.I., Milchevskaya, Ya.G., Tkacheva, Yu.A., et al., Nuclear-nucleolar polymorphism in the regional populations off our species of conifers Factors, Exp. Evol. Org., 2013, vol. 12, pp. 50–54.
Korshikov, I.I., Tkachova, Yu.A., Lapteva, H.V, et al., The nucleus-nucleolus variation in seed progeny of Pinus sylvestris L. var. cretacea Kalenicz. ex Kom. among seed yield of different years from «Melovaya flora» natural reserve, Factors Exp. Evol. Org., 2014, vol. 15, pp. 196–200.
Korshikov, I.I., Kalafat, L.A., and Milchevskaya, Y.G., Genetic diversity and mating system of Pinus brutia var. Stankewiczii sukacz. in small localities of Sudak (Crimea), Cytol. Genet., 2015, vol. 49, no. 2, pp. 29–37. https://doi.org/10.3103/S0095452715020048
Krasikova, A. and Kulikova, T., Identification of genomic loci responsible for the formation of nuclear domains using lampbrush chromosomes, Noncoding RNA., 2019, vol. 6, no. 1, art. ID 1. https://doi.org/10.3390/ncrna6010001
Kumar, P. and Singhal, V.K., Nucleoli migration coupled with cytomixis, Biologia, 2016, vol. 71, pp. 651–659. https://doi.org/10.1515/biolog-2016-0076
Lafontaine, D.L.J., Riback, J.A., Bascetin, R., et al., The nucleolus as a multiphase liquid condensate, Nat. Rev. Mol. Cell Biol., 2021, vol. 22, pp. 165–182. https://doi.org/1038/s415 80-020-0272-6
Ma, T.-H., Lee, L.-W., Lee, Ch.-Ch., et al., Genetic control of nucleolar size: An evolutionary perspective, Nucleus, 2016, vol. 7, no. 2, pp. 112–120. https://doi.org/10.1080/19491034.2016.1166322
Ma, T.-H., Chen, P.-H., Chin-Ming Tan, B., et al., Size scaling of nucleolus in Caenorhabditis elegans embryos, Biomed. J., 2018, vol. 41, no. 5, pp. 333–336. https://doi.org/10.1016/j.bj.2018.07.003
Manzano, A.I., Herranz, R., Manzano, A., et al., Early effects of altered gravity environments on plant cell growth and cell proliferation: characterization of morphofunctional nucleolar types in an Arabidopsis cell culture system, Front. Astron. Space Sci., 2016, vol. 3, art. ID 2. https://doi.org/10.3389/fspas.2016.00002
Mayer, C. and Grummt, I., Cellular stress and nucleolar function, Cell Cycle, 2005, vol. 4, no. 8, pp. 1036–1038. https://doi.org/10.4161/cc.4.8.1925
Montiel, E.E., Manrique-Poyato, M.I., Rocha-Sánchez, S.M., et al., Nucleolus size varies with sex, ploidy and gene dosage in insects, Physiol. Entomol., 2012, vol. 37, pp. 145–152. https://doi.org/10.1111/j.1365-3032.2011.00822.x
Olson, M.O. and Dundr, M., Nucleolus: Structure and Function, Chichester: Wiley, 2015. https://doi.org/10.1002/9780470015902.a0005975.pub3
Book
Severine, B., Westman, B.J., Saskia, H., et al., The nucleolus under stress, Mol. Cell, 2010, vol. 40, no. 2, pp. 216–227. https://doi.org/10.1016/j.molcel.2010.09.024
Sobol, M.A., Role of the nucleolus in plant cell response to environmental physical factors, Cytol. Genet., 2001, vol. 35, no. 3, pp. 72–84.
Tikhonova, I.V., Correlations of heterozygosity with sexual type and sensitivity of Pinus sylvestris L. trees to the influence of environmental factors, Contemp. Probl. Ecol., 2015, vol. 8, pp. 457–463. https://doi.org/10.1134/S1995425515040149
Tkachova, Yu.O. and Korshikov, I.I., Nuclear-nuclear polymorphism of the seed progeny Picea abies (L.) Karst. (Pinaceae) in natural populations and introductory stands, Ukr. Bot. J., 2012, vol. 69, no. 6, pp. 919–925.
Velichko, A.K., Razin, S.V., Kantidze, O.L., DNA damage response in nucleoli, Mol. Biol., 2021, vol. 55, pp. 182–192. https://doi.org/10.1134/S002689332102014X
Voytyuk, V. and Andreeva, V., Nucleolus activity in sprout meristem of scotch pine plus trees, Bull. Ukr. Assoc. Genet. Breed., 2009, vol. 7, no. 2, pp. 177–183.
Yang, K., Yang, J., and Yi, J., Nucleolar stress: hallmarks, sensing mechanism and diseases, Cell Stress, 2018, vol. 2, no. 6, pp. 125–140. https://doi.org/10.15698/cst2018.06.139
Zharskaia, O.O. and Zatsepina, O.V., Dynamics and mechanisms of the nucleolus reorganization during mitosis, Tsitologiia, 2007, vol. 49, no. 5, pp. 355–369. https://doi.org/10.1134/S1990519X07040013