BMs are organisms that can cause mutations, ie can affect the organism and genetic make up of other living beings. This group includes viruses, bacteria, protists, fungi, some worms, but also chemical products of some plants, lower animals as well as genetically modified organisms (GMO). We call them biological mutagens because of their origin,however, the effects they exert on hereditary material are similar if not characteristic of some chemical mutagens.
GMOs are products of incorporating genes into the genome of other organisms, thus permanently altering the host genome. Genetic engineering techniques allow for the introduction of new traits as well as greater control over traits when compared to previous methods, such as selective breeding and mutation breeding. Humans have actually been performing a low-tech version of the GM process for thousands of years through selective breeding. Ancient farmers did it with maize (that’s sweetcorn to us), and transformed a tough, indigestible grain into the juicy yellow kernels we know today. Genetic engineering can actually be used to increase the nutrient density in food. The now famous “Golden Rice Project” is a good example. Food scientists modified ordinary rice to be rich in vitamin A and this is now grown in areas where vitamin A deficiency is a major cause of child mortality and blindness.
Viruses - how they affect our genome
Viruses, due to their variability, affect the host organisms in many different ways. Biology of the virus guarentees the incorporation of the virus genome into the genome of the host cell, and is in and of itself a sufficient precondition for the occurrence of mutational changes in an infected cell.
Viruses can cause both genetic and chromosomal changes, but in addition to mutations can cause changes in the early development of the organism, as in the case infections during pregnancy, fetal abnormalities and tetratogenic effect. Cases of the causative virus are also known as infectious diseases, altered gene function, or even chromosome disruption. This signifies a high degree of mutagenic potential of the virus. The most researched viruses that cause such mutations are:
Simian virus 40 (SV40), has been found in monkeys and humans. It belongs to polymaviruses, and can potentially lead to development of tumors, but is most often reflected in the form of latent infection. It became the star of a already controversial topic after discovering that millions of people were exposed to the virus by receiving contaminated polio vaccines.
Coxsackie virus belongs to the group of RNA viruses, which means that they have a single-stranded, linear RNA. The source of infection is a man, and it is transmitted by feco-oral route. They most common consequences are microarditis, pericarditis, meningitis, herpangina, respiratory infections.
Epstein-Barr virus is the cause of infectious mononucleosis, also known as kissing disease, but it can also be a cause of cancer, meaning it has oncogenic potential. It belongs to the Herpesviriade group. Once the person is infected it multiplies in the pharynx and nose.
Herpes simplex - We distinguish HSV1 and HSV2. HSV1 is found in the mouth and throat, while HSV2 is found in genital region. This virus is very widespread and antibodies are defective in as many as 90% of people over 60. The tetratogenic effect is the appearance of anatomical and psychological damage to the fetus.
Varicella: It belongs to the heroesviraide family. The genome is contained in the DNA chain, protected by a protein coat. The size varies between 150 and 200 nanometers. In nature it exists in itself in one antigenic form. It has the ability to replicate only in human cells. Like the others viruses of this family, it replicates intranuclearly creating a cytopathogenic effect. It causes two clincly very different diseases: chickenpox and herpes zoster, or primary and secondary disease.
Chickenpox (sheep smallpox): Incubation lasts from 2 to 3 weeks, followed by a high fever and a gradually forming polymorphic rash, which lasts 3/4 days. The disease usually passes without complications.
Herpes zoster: Occurs in adults who have had chickenpox in childhood and is characterized by fever and minor rash. In 50% of cases the changes occur on the trunk and neck, and last for apporoximately 14 days.
Oncogenic genes are genes that cause cancer. They are usually inactive in all cells of the body, however, there are some viral genes (viruses) that can activate them. Such as HTLV-1 and HTLV-2, which activate leukemia.
Bacteria that cause diseases
Treponema pallidium - Spirocheta, long but thin in shape. It is caused by Syphilis, one of the most difficult sexually transmitted diseases.
Listeria monocytogenes - a pathogenic bacterium. 21 species have been identified, it is found everywhere in nature. It causes an intestinal infection - listeriosis.
Toxiplasma gondii - an intracellular parasite, found in nature in 3 forms. It is transmitted through root vegetables or insufficiently cooked meat.
Genetic toxicology deals with the detection of the potential mutagenic effect of all environmental factors, due to the growing dangers. Its job is to prohibit the use of certain products and their removal from the market in order to protect us and our genome of its potentially harmful effects.
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