The involvement of different mobile LINE copies of blood plasma and extrachromosomal DNA of liver cells in systemic adaptive response.

The aim of this work was to investigate the dynamics of the quantity of LINE in the DNA composition of blood plasma and extrachromosomal DNA of liver cells under conditions of either immobilization or exposure to ionizing radiation or a combination of both factors. It has been established that post-stress changes in the quantity of genetic elements may be interpreted as an activation of the mechanisms of retroposition and intercellular transfer of genetic elements that ensure the formation of adaptive responses at the systemic level. The formation of adaptive responses is expressed through the reduction of the content of the low-molecular-weight fraction of the extracellular DNA.

[Effect of extreme factors, differing in nature, on distribution of repetitive sequences in extracellular DNA].

Extreme exposures induce changes of content and fractional composition of extracellular DNA. The degree of these changes is dependent on the nature of stressor and conditioned by genome destabilization. The character of distribution in the separate fractions instable in genome of repeating sequences determines the function of extracellular DNA as an adaptogenic factor.

Postradiation DNA polymorphism.

The presence of DNA molecules with tumor-specific genetic alterations has been demonstrated in the plasma of cancer patients. Such plasma DNA fragments may be immunogenic and provide immunologic support to the malignant cells. Further, the tumor-specific plasma DNA may participate in the adaptive processes of the tumor cells in the cancer host.

[Changes in the content and fractional composition of blood plasma nucleic acids in radiation lesions. The effect of radioprotectors].

The content of DNA in blood plasma increased in early stages after irradiation (2 and 5 h), the low-molecular DNA (160-180 bp) being revealed as opposed to intact animals. Protection of gamma-irradiated rats by cystamine or gammaphos enhanced this phenomenon. The injections of cystamine and gammaphos to nonirradiated animals stimulated DNA ejection into blood stream in 2 h only with normalization by 5 h.

[Structure of low-molecular DNA in the blood plasma of irradiated rats].

Low-molecular DNA in blood plasma of rats appeared after gamma-irradiation in a dose 8-100 Gy. This DNA has been cloned and the 26 clones have been sequenced. The search for sequence similarity between the designated sequences and sequences in EMBL allowed the three homology to LINE 3 sequences to be found.

Extracellular DNA level in the blood of irradiated rats.

There is high-molecular DNA in the blood of unirradiated rats which moves as a single fraction during electrophoresis in 0.5% agarose. At short times (2-5 h) after gamma-irradiation at doses from 1 to 100 Gy a low-molecular species of DNA appears (about 180 nucleotide pairs), the amount of which is directly proportional to exposure dose at 5 h after exposure.

[Contents of extracellular DNA in blood of irradiated rats].

Intact rat plasma contains high-molecular DNA which moves as a single fraction in 0.5% agarose electrophoresis. As early as 2-5 hours after gamma-irradiation in a dose of 1-100 Gy there appears low-molecular DNA (about 180 nucleotide pairs), the amount of which directly correlates with the irradiation dose 5 hours after the exposure.

[Changes in the serum fraction composition of nucleic acids in radiation injuries. Alterations in an early period after gamma-irradiation of rats].

The content and fractional composition of nucleic acids of blood serum change after lethal (8 Gy) particularly superlethal (100 Gy) gamma-irradiation of rats. This concerns DNA the content of which increases by 7 times 5 h following 100 Gy irradiation. It has been shown by electrophoresis in 0.