In human cells for the first time discovered a new form of DNA

Scientists from the Australian Institute of medical research Garvan reported the discovery in human cells of unusual structures of DNA i-motifs (intercalated-motif or i-motif). As reported in a paper published in the journal Nature Chemistry, previously, a similar structure could be obtained only in the laboratory and in living cells they were first discovered.

The most common form of DNA is a double chain, consisting of a twisted helix and oriented to each other by four nitrogenous bases: adenine, guanine, thymine and cytosine. Thus in the double helix nitrogen bases of one chain are connected with the bases of opposite chains only in strict compliance. For example, adenine connects only with thymine neighboring chain, and guanine only with cytosine.

However, the structure of i-motif is chetyrehsotletney node where the same cytosine “interwoven” with cytosine on the same circuit.

For the first time about the similar structure of DNA became known in the 90-ies, when scientists were able to obtain i-motifs by artificial means in the laboratory. Scientists generally doubted that i-motifs can exist in the cells of living beings, because the most suitable environment for them was acidic, uncharacteristic of the body of the same person.

To find them, Australian researchers have created a molecule antibodies, which can recognize and attach to these hosts. Her illuminating fluorescent methods, the scientists were able to see where and when appear in the DNA of the nodal structure.

“More likely we were surprised when saw that the green areas — i-motives appear and disappear from time to time. So we learned that they are formed, dissolved and re-emerge”, says one of the authors Mahdi Serati.

Scientists have found that knots are formed at the final stage of G1 phase (the first of four phases in the life cycle of cells). At this time, the cell increases in size and synthesizes RNA and proteins necessary for DNA synthesis. Most often i-motifs appear in the promoter areas that are responsible for the intensity of gene expression in the cell.

The exact function i-of the motives of scientists are not clear yet. But according to one of assumptions, these nodes may participate in the regulation of gene activity by helping to “enable” or “disable” individual genes, and to influence actively the gene is read or not.

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