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Methylation during development

During normal development and cell differentiation in mammals, a complex of changes in DNA methylation occurs.

(Fig. 2). In the zygote (immediately after fertilization), maternal and paternal chromosomes are spatially separated, and their demethylation occurs

Development time

Figure 2.

Schematic representation of temporal changes in the level of DNA methylation in mammalian cells during development

(Turker 1999). AUC - primordial germ cells, hESC - embryonic stem cells.

at different times (Mayer et al. 2000). In this case, the paternal chromosomes are demethylated within six to eight hours after fertilization, independent of replication, while demethylation of the maternal chromosomes encompasses the stages of second and third cleavage and occurs during the replication process. In mice, as a result of this process, the genome methylation level drops to 30% of that observed in somatic cells (Kafri et al.
1992). After implantation in the blastocyst cells, the methylation level is restored, acquiring a pattern characteristic of the cells of the adult organism (Turker 1999). This process begins de novo methylation, affecting specific sequences in the genome ("methylation centers" - transposons and repeats). After that, at the second stage of establishing the methylation pattern, methylation from the center is distributed to the surrounding unmethylated sites. During differentiation in

cells significantly decrease the ability to methylate DNA de novo (Turker et al. 1991; Szyf et al. 1990), but retain the ability to spread methylation from "methylation centers" (Toth et al. 1989). However, an extremely high ability to maintain the established methylation status during replication becomes a characteristic feature of cells. This process is called supporting methylation.
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Methylation during development

  1. Research of mental development in New time
    The development of society in modern times led to the need to develop an objective scientific basis under the views expressed by humanists about the human psyche. For this, it was important to substantiate objective methods for studying the content of the soul, showing that the knowledge gained through scholastic verbal operations cannot be considered true. The English philosopher and politician F. Bacon is
  2. Petrenko A.A. DNA methylation analysis for cervical cancer, 2003
    Introduction DNA methylation Distribution of DNA methylation DNA methylation function Methylation during development Methylation enzymes Methylation as a dynamic process The role of methylation in carcinogenesis Genetic role of DNA methylation in carcinogenesis Epigenetic role of DNA methylation in carcinogenesis Comparative analysis of modern status determination methods
  3. Methylation enzymes
    Methylation of the cytosine residue is the transfer of the methyl group from the donor molecule to the fifth carbon atom in the cytosine molecule by enzymatic means. Two independent methylation processes are observed in the cell, apparently carried out by different DNA methyltransferases. In the first case, the acquisition of the methylated status of a CpG dinucleotide, which has not previously been methylated, is observed
  4. Methylation as a dynamic process
    The status of DNA methylation in any cell is established as a result of a combination of dynamic methylation and demethylation processes. In a population of CpG cells, dinucleotides can have one of three methylation profiles (Turker 1999): fully methylated (the methylation level is almost 100%), unmethylated (about 0%) and partially methylated (between 0 and 100%) - representing the average
  5. The role of methylation in carcinogenesis
    In relation to the normal regulation of DNA methylation, there are two disorders that are characteristic of tumors. Almost all types of transformed and tumor cells simultaneously have widespread genome loss of methylation in normally methylated sites and local hypermethylation of CpG islands unmethylated in normal cells (Fig. 3). Each of these
  6. DNA methylation function
    The most common function of methylation is to participate in cellular "immunity." For bacteria, it is characteristic as an element of the methylation-recognition system "friend-foe", which allows the cell to distinguish its genetic material from foreign molecules that have penetrated the cell. This allows you to maintain the genetic stability of the species. Sometimes one enzyme performs both methylase and endonuclear
  7. Distribution of DNA methylation
    Methylation of bases in DNA was discovered over 50 years ago and is observed in almost all classes of living organisms. The DNA of prokaryotes contains the modified bases of p-methyladenine and 5-methylcytosine, whereas eukaryotes are characterized mainly by the presence of 5-methylcytosine. It is present in the DNA of fungi and plants (Finnegan et al. 2000; Martienssen and Colot 2001). In the animal kingdom there is
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  9. Epigenetic role of DNA methylation in carcinogenesis
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  10. DNA methylation
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  12. Curb time
    In the case of classical time planning, tables are usually used. Either it is a calendar with various schedules (for a year, month, week, day), or task lists. Intellect card as a graphic aid is an alternative or addition to the table. Planning only with the help of mind maps or combining a calendar and a mind map depends on the number of your meetings.
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