[Chromatin diminution at the border of the XX and XXI centuries].

The size of genomes in eukaryotic organisms is one of the greatest mysteries of biology. As known from the middle of the XX century, the level of organization of a particular organism, does not depend on its genome size, i. e. on DNA amount in the nucleus. We believe that an actual function of non-coding DNA stands behind the phenomenon of chromatin diminution, known already for 100 years. Diminution of chromatin normally takes place in cells involved in body building and never occurs in developmental precursors of germ cells. Apparently, the former are cells, in which non-coding DNA is functionally significant. We cloned a fraction of DNA eliminated during chromatin diminution of Cyclops kolensis (Cyclopoida, Crustascea) and sequenced 90 clones totally making 32 kb. Taken together, the provided evidence has demonstrated a high organization ordering of DNA sequences restricted to the germ line. Chromatin diminution never takes place in human cells and in cells of the majority of animals. These cells may isolate non-coding DNA in other ways, making it unreactable for most enzymes and thus functionally cut off. Thus, a certain part of genome with a particular size and structure may serve for genetic isolation of species as shellfish or junk DNA are vital components rather than pieces of garbage.

[The peculiarities of the radiation mutagenesis of Cyclops kolensis and Cyclops insignis (Crustacea, Copepoda)].

The frequency of the chromosomes aberrations (FA) of Cyclops kolensis before chromatin diminution (CD), which were inducted by gamma-irradiation in 50 times exceeds the FA of Cyclops kolensis after CD, during the CD, reducing the genome of C. kolensis in 15 times. During the embryogenesis the FA of Cyclops insignis doesn't change. The obtained results show us a low level of the spontaneous mutagenesis of C. kolensis and C. insignis embrios. The FA of Cyclops kolensis is correlated with the doses 1, 2, 3, 5 Gy gamma-irradiation. The similarity of the CD mechanism and of the mechanism of the chromosome aberrations is supposed.

[Some conclusions on the role of redundant DNA and the mechanisms of eukaryotic genome evolution inferred from studies of chromatin diminution in Cyclopoida].

The absence of progress in understanding the problem of redundant eukaryotic DNA is stated. This is caused primarily by the attempts to solve this problem either in terms of the traditional approaches (the general phenotypic parameters such as developmental rate, body size, etc. depend on the genome size) or by introducing such vague terms as egoistic, parasitic, or junk DNA. Studying chromatin diminution (CD) in copepods yielded two important conclusions. First, part of the genome of a certain size (94% in Cyclops kolensis first described by the authors) is not needed for somatic functions as it is eliminated during the early (third to seventh) cleavage divisions from the presumptive somatic cells. Second, this DNA is not redundant, let alone selfish or junk, relative to the germline cells. In this sense, it can be regarded as invariant (monomorphic) trait that characterizes the species. Analysis of cloned and sequenced DNA regions eliminated from the somatic cell genome by CD (i.e., confined to the germline), which was first carried out for C. kolensis, showed that the molecular structure of this DNA has at least two features of regular organization: a mosaic structure of repetitive sequences and high (sometimes up to 100%) homology between different repeats and subrepeats. We have suggested that the germline-restricted DNA forms a unique molecular portrait of the species genome, thus acting as a significant factor of genetic isolation. Yet, the phenomenon of CD proper as it occurs in Cyclopoida without disintegration of the chromosome structure) may be regarded as a model of reductional genome evolution, which has repeatedly occurred in the history of eukaryotes.

[Chromatin diminution is a key process explaining the eukaryotic genome size paradox and some mechanisms of genetic isolation]. / Diminutsiia khromatina--kliuchevoi protsess dlia ob''iasneniia paradoksa razmera genoma éukariot i nekotorykh mekhanizmov geneticheskoi izoliatsii.

The functions of redundant (junk, selfish, parasitic, etc.) DNA in eukaryotes can be reliably inferred from chromatin diminution (programmed elimination of up to 94% of the genome from somatic germ cells in Ascaris and Cyclops). These functions should be sought in germ cells, where this DNA is preserved during the entire life time of the species. A possible biological role of redundant DNA as a factor disrupting meiotic chromosome synapsis is suggested. At the same time, chromatin diminution itself can act as a mechanism of postzygotic isolation. All stage of the complex diminution mechanism could not be fixed in the genetic program of the species via gradual accumulation of mutations. The "program" of diminution must have appeared at once and in the completed form.

[Chromosomal radiosensitivity as associated with chromatin diminution in cyclops (Crustacea, Copepoda)]. / Radiochuvstvitel'nost' khromosom v sviazi s diminutsiei khromatina u tsiklopov (Crustacea, Copepoda).

Chromosomal radiosensitivity inferred from the yield of chromosome aberrations (CAs) was for the first time studied in Cyclops (Crustacea, Copepoda) before and after chromatin diminution (CD). A comparison was made for C. kolensis, in which CD denudes somatic embryo cells of the greatest (94%) DNA amount known for multicellular organisms, and C. insignis, which lacks CD. The two species have similar genome sizes, 4.6 and 4.3 pg. respectively. Radiosensitivity of C. kolensis chromosomes proved to be extremely high during prediminution cleavage divisions. This was attributed to membrane damage in granules that contain enzymes (topoisomerases) normally involved in cleavage and ligation of chromosomal DNA during CD.

[Nuclear genetic material as an initial substrate for animal aging]. / Iadernyi geneticheskii material kak initsial'nyi substrat stareniia zhivotnykh.

General properties of aging in animals are considered on the basis of the literature evidence and the results obtained by the authors of this paper. The existence of a specific aging mechanism is inferred. The operation of this mechanism is controlled not only by genes but also by particular noncoding genomic sequences with variable structure. The beginning of senescence in animals is determined by DNA lesions located in neural cells and probably in a minor genomic fraction. The authors refute the narrow concept of aging as a mechanism increasing the probability of death. Mortality as a continuous process occurring with the probability of 100 percent is an integral attribute of living organisms on the Earth.

[Comparative analysis of the life span in HA and BA Drosophila melanogaster]. / Sravnitel'nyi analiz prodolzhitel'nosti zhizni linii HA i BA Drozophila melanogaster.

We studied lifespan (LS) of Drosophila melanogaster strains HA and BA. The first one was generated by long-term selection for low male sexual activity and features decreased LS as well as the changes in a relatively constant index--coefficient of LS variation. The BA strain was derived from the HA strain by reverse selection and has the mean LS and coefficient of LS variation similar to those of the normal strain D-32. Analysis of the death curves of the HA strain insects does not exclude existence of a subpopulation with the normal LS within these strain. The obtained data are discussed in the context of possible involvement of mobile element transposition in animal LS control.

[The anthropic principle in biology and radiobiology]. / Antropnyi printsip v biologii i radiobiologii.

In accordance with the anthropic principle of the Universe the physical constants of fundamental particles of matter and the laws of their counteraction are those that an appearance of man and mind becomes possible and necessary. It is suggested to add some biological constants to the set of fundamental constants. With reparation of DNA as an example it was shown how a cell ran some parameters of Watson-Crick double helix. It was pointed that the concept of the anthropic principle of the Universe in its full body including biological constants is a key to developing of a unified theory of evolution of the Universe within the limits of scientific creationism.

[Diminution of chromatin, accompanying reorganization of genomic molecular structure: evolutionary aspects]. / Diminutsii khromatina, soprovozhdaiushchiesia reorganizatsiei molekuliarnoi struktury genoma: évoliutsionnye aspekty.

Chromatin diminution (CD) accompanied by the reorganization of the molecular genomic structure of macronuclei in ciliates and somatic cells in Cyclops and Ascaris is considered. A conclusion is drawn that the physical elimination of most (sometimes 94-98%) genetic material from somatic nuclei directly indicates that, in these species, eliminated sequences possess neither the coding nor the regulatory functions that are required for differentiation. Apparently, the actual functions of eliminated sequences are associated only with germline chromosomes where these sequences act as a factor of genetic isolation. A CD is supposed to be underlain by the coordinated operation of many genes. Consequently, this phenomenon cannot result from stochastic mutagenesis and the random coincidence of required mutations in several genes. For CD formation, canalized mutagenesis is required, which simultaneously generates a set of genes that code the consecutive stages of CD.

[Ionizing radiation and 5-bromo-2'-deoxyuridine as tools for analysis of the fundamental mechanism of aging in animals]. / Ioniziruiushchie izlucheniia i 5-brom-1'-dezokiuridin kak instrumenty analiza fundamental'nogo mekhanizma stareniia zhivotnykh.

The influence of gamma-irradiation and 5-bromo-2'-deoxyuridine (BUDR) on the life span and behaviour (in photoactivity test) of D. melanogaster was studied. It was found that gamma-irradiation resulted in decrease of life span. However the form of survival curves changed only under exposure to doses higher than 500 Gy. Treatment with BUDR distorted the form of survival curves and caused death of insects immediately after exclusion. It also caused abrupt decrease in photoactivity of insects, while irradiation even with very high doses did not affect this feature. It is proposed that initiating substrat in drosophila aging is DNA of nerve cells. The possible relationship between aging regularities and evolutional extinction of eucaryotic species is discussed.

[The effect of 5-bromo-2'-deoxyuridine on the lifespan and behavior of Drosophila melanogaster]. / Issledovanie vliianiia 5-brom-2'-dezoksiuridina na prodolzhitel'nost' zhizni i povedenie Drosophila melanogaster.

In this study, we have examined the effect of 5-bromo-2'-deoxyuridine incorporated into DNA of Drosophila nerve cells after incubation of larvae in the analog-containing medium on the duration of lifespan and behavior (photoactivity) of adult flies. 5-Bromo-2'-deoxyuridine incorporated into DNA decreases the lifespan of adult animals. In contrast to the control, the curves describing the probability of death become bimodal at higher doses of the analog (above 35 (g/ml). As the dose of 5-bromo-2'-deoxyuridine decreases, photoactivity of the flies diminishes, and the distribution into fractions with different activity becomes broader. The data obtained provide evidence that the modification of DNA with 5-bromo-2'-deoxyuridine drastically changes the expression of tissue-specific genes in nerve ganglia of Drosophila and at the same time diminishes the duration of insects lifespan. These observations suggest that genome of the nerve cells appears to be a probable initial substrate of Drosophila aging.

[Chromosome aberrations, chromatin diminution and their significance in understanding the molecular genetic organization of eukaryotic chromosomes]. / Aberratsii khromosom, diminutsiia khromatina i ikh znachenie v ponimanii molekuliarno-geneticheskoi organizatsii khromosom éukariot.

The paper analyzes the significance of new data obtained in the study of mechanism of formation of radiation-induced chromosome aberrations and in the investigation of chromatin diminution for understanding of the principles of the molecular genetical organization of eucaryotic chromosome. It is concluded that the structure of eucaryotic chromosome follows a certain plan. For its formation, a large number of various innovations were necessary, which could not been prepared simultaneously under the directed action of natural selection based upon the stochastic mutation process.

[The frequency of chromosome aberrations in the lymphocytes of children with thyroid diseases living in Bryansk Province]. / Chastota aberratsii khromosom v limfotsitakh detei s zabolevaniiami shchitovidnoi zhelezy, prozhivaiushchikh v Brianskoi oblasti.

The number of unstable chromosome aberrations was determined in peripheral blood lymphocytes from 15 children with thyreopathology living in Klintsy (Bryansk Province); the mean age was 14 years. The number of dicentric chromosome is determined to be (0.18 +/- 0.07) per 100 cells and is significantly higher than that in cells from healthy children of Klintsy and Moscow (control). There was no differences in the frequency of other types of chromosome aberrations as well as of aberrant cells.

[The cytogenetic examination of different groups of children living in regions of Bryansk Province contaminated as a result of the Chernobyl accident]. / Tsitogeneticheskoe obsledovanie razlichnykh grupp detei, prozhivaiushchikh v raionakh Brianskoi oblasti, zagriaznennykh v rezul'tate Chernobyl'skoi avarii.

The frequency of chromosome aberrations (CA) was studied in peripheral blood lymphocytes from healthy children and children with thyreopathology living in the city of Klintsy, Bryansk Province (contamination level up to 5 Ci/km2), and two Moscow groups, respectively. We have observed the elevated number of dicentrics and acentric fragments in cell from children with thyreopathology with respect to those from healthy children living in Klintsy. This fact cannot be explained by influence of disease because there was no difference in cytogenetical markers between the groups of healthy children and children with thyreopathology from Moscow. The number of dicentrics was increased in cells from children with high level of internal contamination (more than 400 nCi) living in Krasnaya Gora (15-40 Ci/km2). It is proposed that the internal irradiation is more important for the CA induction. The symmetrical translocation analysis using the method of fluorescence in situ hybridisation (FISH) has shown the absence of this type of aberrations in cells from children with high level of internal irradiation whereas the translocations frequency in cells from control children was (1.1 +/- 0.4) per 1000 cells.

[The G1-process in human lymphocytes cultured with PHA, and formation of radiation-induced chromosome aberrations]. / G1-protsess v limfotsitakh cheloveka, kul'tiviruemykh s FGA, i obrazovanie radiatsionno-indutsirovannykh aberratsii khromosom.

Experimental evidence for the existence of local spontaneous DNA synthesis in PHA-stimulated human lymphocytes at the G1 phase (G1 process) is presented. This process is associated with the appearance of single-stranded DNA breaks and their subsequent reparation. DNA sequences involved in the G1 process were characterized in terms of their nucleotide composition and association with the nuclear matrix. It was shown that the G1 process occurs in chromosome regions in which radiation-induced exchange-type chromosome aberrations arise. The results of the study are regarded as evidence in favor of a molecular version of the primary contact theory of chromosomal mutagenesis. A possible role of G1 process disturbances in pathogenesis of chromosome instability syndromes in humans is discussed.

[An evaluation of the radioprotective action of antioxidants on normal human cells and in genomic diseases by using different cytogenetic tests]. / Otsenka radiozashchitnogo deistviia antioksidantov na kletki cheloveka v norme i pri bolezniakh genoma s pomoshch'iu razlichnykh tsitogeneticheskikh testov.

In studying the radioprotective action of natural and synthesised antioxydants a decreased yield of chromosome aberrations with respect to those in untreated cells was noted in normal cells irradiated in phase G1 whereas no radioprotective effect was found in cells irradiated in G0. The addition of antioxydants into the cell cultures from patients with Turner's syndrome did not change their radiosensitivity. No adaptive response was induced in lymphocytes from patients with Down's syndrome cultivated with vitamin E.