低能重离子生物学研究进展

Progress in Lower Energy Heavy Ions Biology Research

从低能重离子集能量、动量、质量和电荷于一体的特点出发,总结了低能重离子在细胞框架结构、自由基、DNA和染色体、植物生理等方面的生物学效应及其剂量效应模型的研究现状,介绍了低能重离子在生物诱变育种及转基因、细胞融合等方面的应用,并对低能重离子生物学研究中存在的问题和发展方向作了阐述。

Lower energy heavy ions(LEHI) refer to the ions with energy between 104 ～105 eV,listed behind He in Element Table and surface electron being full or partly deprived.Besides the common characters of heavy ions,LEHI has its unique characters.Energy of LEHI can be transferred to target when they collide elastically.And the collision and energy transfer should be a chain action.Unlike normal radiation,breaking of bands in organic molecular caused by LEHI does not obey the rule of 'Weak bands first'.Mass deposition is another important character of LEHI.When energy of ions decreases to 20 eV,implanted ions may stop in the target.This means a new substance is added into the target.Bumped by LEHI,substance of the target self may move from one area to another.Also,if the input ions happened to be active ions of life,it may bind into an original molecular,thus the new organic molecular is formed.Charge neutralization and exchange is the third character of LEHI.Together with ions,charges are also input into target,which may neutralize target charge,or directly disturb the micro pH condition.Combining with energy,mass and charge,LEHI has unique biological effects.Reports on this topic falls into six aspects.(1)LEHI etches and cuts into cell surface,and impacts cell ultrastructure.(2)LEHI causes changes in substance and charges.(3)LEHI causes free radical metabolism disturbance.(4)LEHI causes DNA doublestrand breaks(DSBs) and gene mutation.(5)Effects of LEHI on plants growth and their physiology.(6)Models of dose and biological effects for LEHI.Among them the fourth aspect is the most ardent topic.The relatively higher mutation frequency of LEHI than the other radiation is the main reason for its prevailing in radiation biology.Current applications of LEHI are mainly in mutation inducing and breeding of plants and microorganisms.Materials have been tried including rice,wheat,maize,tobacco,tomato,Vc producing bacterium,etc.Chinese Plasma Academy contributes the most in this area,and has obtained significant economic profits.Other potential applications of LEHI are gene transfer and cell fusion.It is a new area,but regarding current observations during LEHI irradiating biomaterials,this is possible.Quite a few researches are engaged in this area,and several successful attempts have been reported.Although obvious progress has been accomplished in LEHIB,there are still many areas which need to be studied.The urgent problems which should be solved are(1)Suitable equipment for biomaterials,former equipments for physics and chemical researches are not competent in biology research;(2)Biomaterials used in LEHIB are mainly plants and microorganisms.Heavy ions have been used in therapy of tumor and other human diseases.The effects of LEHI on animals and human are hardly studied;(3)Common ideas about physiological effects of LEHI on plants have not been developed;(4)The dose effect and its models should be still discussed.