What is a Mutagen?

Keywords: physical mutagenesis, chemical mutagenesis, mutation breeding

Mutagen

Keywords: physical mutagenesis, chemical mutagenesis, mutation breeding

Anything that can cause sudden or radical changes in the genetic material of an organism

Pros and cons of environmental mutagens. In 1927, American geneticist J. Muller successfully induced x-rays for the first time

Make

Physical mutagens mainly include ultraviolet, ARTP, X-ray, -ray, fast neutron, laser, microwave, ion beam and so on.

1 Mutagen 1 plasma

Abbreviation for Atmospheric and Room Temperature Plasma, which can generate highly active particles (including excited helium, oxygen, nitrogen, OH radical, etc.) concentration of plasma jet. According to the state of thermodynamic equilibrium, plasma can be divided into three types: completely thermodynamic equilibrium plasma (also called high-temperature plasma, whose electron temperature (Te), ion temperature (Ti) and neutral particle temperature (Tn) are completely consistent), local Thermodynamic equilibrium plasma (also called thermal plasma, TeTiTn = 3 × 10 ~ 3 × 10), and non-thermodynamic equilibrium plasma (also called cold plasma, whose TeTi, TiTn).

Atmospheric Pressure Glow Discharge (APGD) is a general term used to describe the cold plasma of various gas discharges under atmospheric pressure. Among various atmospheric pressure unbalanced discharge plasma sources, an atmospheric pressure radio frequency glow glow discharge (RF APGD) plasma source using a bare metal electrode structure is a new atmospheric pressure glow proposed in recent years Discharge cold plasma source. In order to highlight the characteristics of this plasma source from the perspective of biotechnology applications, atmospheric pressure room temperature plasma, or ARTP, is used to represent this RF APGD plasma source.

Scientific research shows that the active particles in the plasma act on the microorganisms, which can change the structure and permeability of the cell wall / membrane of the microorganisms and cause genetic damage, which in turn can cause significant changes in the genetic sequence of the microorganisms and their metabolic networks, and eventually cause mutations in the microorganisms. . Compared with traditional mutagenesis methods, ARTP can effectively cause DNA diversity damage, high mutation rate, and easy to obtain mutants with good genetic stability; ^[1]

2 Mutagen 2 UV

We know that purines and pyrimidines of DNA and RNA have strong ultraviolet light absorption capacity, and the largest absorption peak is at 260nm. Therefore, ultraviolet radiation with a wavelength of 260nm is the most effective mutagen. There are many explanations for the role of ultraviolet light. However, one of the more clearly studied functions is to make DNA molecules form pyrimidine dimers, that is, two adjacent pyrimidines are covalently connected. The presence of dimers will weaken the hydrogen bonding between double bonds and cause distortion of the double-stranded structure. Prevents normal pairing between bases, which may cause mutation or death. In addition, the formation of dimers will prevent the dissociation of double strands, thus affecting DNA replication and transcription. In short, ultraviolet radiation can cause base conversion and inversion Changes, frameshift mutations or deletions. ^[2]

3- Mutant 3-ray

-ray belongs to ionizing radiation and is an electromagnetic wave. It generally has high energy and can produce ionization, so it can directly or indirectly change the structure of DNA. Its direct effect is the oxidation of the base of deoxyribose or the chemical bond of deoxyribose The chemical bond connected to the sugar-phosphate is broken, which causes the single- or double-stranded bond of DNA to be broken. Its indirect effect is that ionizing radiation causes water or organic molecules to generate free radicals. These free radicals interact with the solute molecules in the cell and chemically occur. Changes affect DNA molecules and cause deletions and damages. In addition, ionizing radiation can also cause chromosomal aberrations, chromosome breaks, and loss, translocation and inversion of chromosome structures. ^[3]

4 Mutant 4 laser

The research and development of laser in microbial mutation breeding is relatively late. Laser mutation breeding technology research started in the 1960s. After more than 40 years of development and application research in various countries around the world, not only has it proved that laser and ordinary light are essentially electromagnetic waves, the microscopic mechanism of their light emission and the atoms and molecules that make up the luminescent substance Energy states and changes are closely related. Laser is a kind of radiant light different from natural light. It has the characteristics of high concentration of energy, single color, good directivity and strong directivity. Through the combined effect of light effect, thermal effect and electromagnetic effect, laser can break or form fragments of organism chromosomes, even translocation and genetic recombination. ^[4]

5 Mutant 5 Microwave

Microwave radiation belongs to a kind of low-energy electromagnetic radiation, and has a strong biological effect in the frequency range of 300 MHz to 300 GHz, and has thermal and non-thermal effects on living organisms. Its thermal effect means that it can cause the local temperature of the organism to rise, thereby causing physiological and biochemical reactions. Non-thermal effect means that under the action of microwave, the organism will produce various physiological and biochemical reactions that are not temperature-dependent. Under the combined effect of these two effects, the organism will produce a series of mutation effects. Therefore, microwave has also been used in mutagenesis breeding in many fields, such as crop breeding, animal breeding and industrial microbial breeding, and has achieved certain results. ^[4]

6 Mutagen 6 ion beam

Ion implantation is a new technology emerging in the early 1980s, which is mainly used for the surface modification of metal materials. Since 1986, it has been gradually used for crop breeding. In recent years, this technology has been gradually introduced into microbial breeding. Ion implantation mutagenesis is a method of generating high-energy ion beams (40 ~ 60keV) with ion implantation equipment and implanting them into organisms to cause permanent changes in genetic material, and then selecting excellent strains from mutant strains. Ion beams have energy deposition on the organism (that is, the implanted ions collide with the macromolecules of the organism and gradually lose energy, and the biomacromolecule gradually gains energy and then the bond breaks, the atoms are knocked out, and the biomolecules are left behind. The process of breaking bonds or defects) and mass deposition (that is, implanted ions form new molecules with biological macromolecules), which can cause death, indirect damage to free radicals, duplication of chromosomes, translocation, inversion or DNA Various biological effects such as molecular breaks and base deletions. Therefore, ion implantation mutagenesis can obtain a high mutation rate, with a wide mutation spectrum, low mortality, high positive mutation rate, and stable traits. ^[5]