Using Relaxation Time to characterize biological effects of different mutagens

Abstract

All kinds of mutagenic factors may cause physiological, biochemical and genetic changes of all organisms. To characterize their characteristic biology effects, the concept of Relaxation Time (RT) was introduced for the first time, and the specific process was as follows. After mutation of organisms, the offsprings will be continuingly cultured (or cultivated) to the next generation (Rx). Once a biological effect began to show no significant difference compared to the untreated controls, the Rx was defined as the RT of the effect. In this paper, three kinds of mutagenic factors were selected to treat the seeds or seedlings of Astragalus sinicus L., subsequently, the corresponding RT was calibrated. The results showed that the RT was diverse not only among different biological effects but also among different mutagenic factors. For the RT of chemical mutagens and gamma rays, most of which are concentrated on R 1 , whereas the heavy ion beams have significant differences among different tracks. Among biological effects, the SOD activity and superoxide anion free radical content in the Peak region are more prominent, and their RT reaches R 3 and R 4 , respectively. Thus, the RT may characterize the characteristic biological effects from differently mutagenic factors. Since X-ray increasing mutation rate was discovered in the last century 1-3 , a series of mutations caused by mutagens have received extensive attention, and it has made many achievements in basic research and applied research 4-6. And the application of mutagenic means are also constantly innovating in three fields: physical factors from x-rays, ultraviolet rays, gamma rays to various kinds of charged particles 1-3,7-9 , chemical factors from DNA alkylating agents to alkali analogues 10-12 , and biological factors from the introduction of exogenous genes to the knockdown of internal genes 13-15. Although all kinds of mutagenic factors can cause biological physiological, biochemical and genetic changes, so far, only the change rate of these biological effect indicators is used to distinguish the differences among these factors or these indicators. However, the change rate of these indexes is influenced by different doses, there is a cross between these ratios. Thus, it is hardly possible to distinguish the characteristic biology effects of different mutagenic factors at present. There are direct and indirect effects in mutagenic biological effects, and direct effects will directly affect indirect effects. As a result, we try to grasp the characteristics of indirect effects to characterize the biological effects of different factors by the Relaxation Time (RT, a concept from thermodynamics) as a new characterization index. The RT indicates the time required for a system to move from an unstable state to a stable state. Since the life system is also a complex and open thermodynamic system 16-18 , when undergoing mutagenesis, the change of the life system is a normal thermodynamic reaction, and when the action of mutagenesis weakens or disappears, the resto...