Experimental Evolution In Research

1.2.Experimental evolution

Experimental evolution is an important method for research of evolutionary mechanisms and processes that might happen within. Research consists of quantitative and qualitative descriptions of changes that take place in laboratory conditions. First evolution experiments have started at the end of the 19th century. Although C. elegans has been used frequently as a model in molecular biology, its benefits in evolution biology are still being explored. (Gray et Clutter, 2013) Most of the experiments so far have been done on Escherichia coli but the need for understanding more complex organisms has led to the use of new models, such as C. elegans. Some of the advantages of this model include relatively short life cycle

There are also radio waves, microwaves and infrared radiation with larger wavelengths and gamma-rays with wavelength shorter than X-rays. Three subtypes of UV have been introduced with respect to the wavelength; UVA with range 315-400 nm, UVB 280-315 nm and UVC 100-280 nm (Diffey, 2002). Only 5% of the total UV radiation that reaches Earth is UVB and the rest of it is UVA. UVC is absorbed in the stratosphere and does not reach the biosphere so the UV that reaches the Earth's surface with biggest energy is UVB. It is mostly screened out by ozone but that is changing with the increasing depletion of the Ozon layer. Although UV has benefits some of which are production of vitamin D, role in vision of vertebrates and invertebrates, formation of pigments in plants, it also has many negative effects. It is known that UV causes skin cancer, damages eyes and tissues and leads to different ecological effects. (Yagura et al., 2011) Consequences of UV irradiance on humans, plants, animals and the whole ecosystem are numerous. It has been shown that artificial UVC does extreme damage to exposed tissues. It is strongly absorbed by nucleic acids and its impact on different biological models has been studied the most. Many of those researchers have had a goal to examine DNA damage and repair. Human population and

Induction of lesions depends on wavelength of UV radiation but also on the composition of DNA. It has been shown that the relative absorption obtained from different species depends on the guanine-cytosine content (Sutherland et Griffin, 1981). Maximum of absorption of DNA is around 260 nm, so the UVC the most effectively induces DNA photoproducts. Exposition of DNA to UV causes dimerization of the neighbouring pyrimidines so the main products are cyclobutane pyrimidine dimers and pyrimidine (6-4) pyrimidone photoproducts. In addition, there is an indirect DNA damage that arises from reactive oxygen species (ROS). DNA lesions formed because of ROS can be recognized as a formation of dihydro-8-oxoguanine, usually due to UVA or UVB. That is often considered as a premutagenic lesion whereas single-strand break is a lesion with little influence in formation of mutation. Cells have developed DNA repair mechanism to deal with DNA damages. (Yagura et al.,