Genus Abies among woody plants is very sensitive to unfavorable ecological factors. Fir forests have been heavily disturbed in different regions over the past few decades (Bazhina, Tretyakova, 2001). The aim of the researches is comparative study cytogenetical signs of Abies sibirica seeds in healthy and disturbed West Sayan mountains forest ecosystems. The seeds were collected in low (village Tanzibei, 450 a.s.l.) and high mountains (meteostation “Olenya rechka”, 1450 a.s.l.). The researches were carrying out on meristems. The standard techniques with author’s modifications and microscope MBI-6 have been used. Abies sibirica diploid chromosome set consist 24 chromosomes. The chromosome mutations are found in seedlings form both populations. At metaphase stage fragments, a centric rings and ring chromosomes are revealed. In high mountains populations dicentric chromosomes are observed. Total frequency of chromosome reorganizations makes 2,8% in low mountains and 7.5% in high mountains populations. At ana- telophase stage in most cells divisions are regular. The frequency of irregular mitoses is 2.2±0.5% in low mountains and 4.1±0.9 % in high mountains. The chromosomes outside spindle divisions, bridges, lagging chromosomes and irregular and multipolar chromosome divergence are observed. At the first time in Abies sibirica micronucleus in interphase cells are detected. There are isolated from nucleus intracellular chromatin structures with own membrane. In low mountain population 15,9% seedlings contain cell with micronucleus. In one seedling there are from 1 to 4 of such cells per 1000, i.e. total frequency is enough low – 0.03%. In high mountain population there are 26,0% such seedlings, some of them contain up to 65 such cells. Total frequency of micronucleus in seedlings of drying trees are 0.2% (in 6,7 time higher than in morphologically healthy trees). It is believed that gearing of post mitotic micro nucleation provide transference of accumulated latent genome irregularities in morphological identified cell forms (Il’inskih et al., 1986; Zhuleva and Dubinin, 1994). As a rule, the micronucleus presence is the result of long influence of different genotoxic factors on organism and reflect the degree of disturbance of ecosystems in habited region. References Bazhina E.V., Tretyakova I.N. To problem of fir forest drying // The successes of modern biology, 2001, v. 121, № 6. P. 626-631. Il’inskih N.N., I.N. Il’inskih, E.F. Bocharov. Patogenetics homeostas and immunity. Novosibirsk: Nauka, 1986. 256p. Zhuleva L.Yu., Dubinin H.P. The use of micronucleus test for estimation of ecological conditions in Astrahchan region // Genetica. 1994. V. 30, № 7. P. 999-1004. The research was financially supported by RFBR (grants №№ 08-04-90001Bel_a, 09-04-98000).

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