Rate of mutation

In a GA, the size of the population, rate of mutation, rate of crossover, choice of selection method, and other factors can all be selected by the user. The fact that this degree of freedom exists does not imply that the value chosen for each parameter is of little consequence. On the contrary, the parameter... 

Apart from gene silencing, other effects of DNA methylation include spontaneous deamination, enhanced DNA binding of carcinogens and increased UV absorption by DNA, all of which increase the rate of mutations, DNA adduct formation and subsequent gene inactivation... 

Dean N, McKay R, Miraglia L, Howard R, Cooper S, Giddings ], Nicklin P, Meister L, Ziel R, Geiger T, Muller M, Fabbro D (19 ) Iidiibition of growth of human tumor cell lines in nude mice by an antisense oligonucleotide inhibitor of protein kinase C-a expression. Cancer Res 56 3499-3507 Defranco AL (1991) Immunosuppressants at work. Nature 352 754-755 De las Alas MM, Aebi S, Fink D, Howell SB, Los G (1997) Loss of DNA mismatch repair effects on the rate of mutation to drug resistance. J Natl Cancer Inst 89 1537-1541... 

Mechanism of Action An antiviral agent that incorporates into DNS causing increased rate of mutation and errors in protein formation. T herapeutic Effect Prevents viral replication. 

All organisms suffer a certain number of mutations as the result of errors in normal cellular operations such as DNA replication. The majority of such mutations are quickly recognized and corrected by specific enzymes that are capable of comparing the two complementary bases on the DNA molecule as replication proceeds. Occasionally, they are not detected and corrected fortunately, these spontaneous mutations are quite rare. The natural incidence of mutations can be increased by exposure to various environmental factors, and the effectiveness of a mutagen is assessed by the degree to which it increases the rate of mutation. 

Why are high rates of mutation observed in regions of DNA that contain 5-methylcytosine ... 

A major effort is being made to devise a vaccine against HIV. However, rapid mutation of the env gene makes it difficult to accomplish.736/736a This high rate of mutation appears to be a result of a high frequency of errors by the HIV reverse transcriptase.737 There is... 

After reaching the lymph nodes, CD4+ cells are rapidly infected and replication of the virus continues. During the initial phase of infection, the virus is spread throughout the body via blood that contains many viral particles. The flu-like symptoms are first observed in about 70% of the patients 2-A weeks after HIV infection. At this stage, HIV titer is reduced due to the development of virus-specific CD8+ cells and due to humoral immune response, which generally causes a return to the normal numbers of CD4+ cells. As the HIV continues to replicate, a person may stay free of HIV-related symptoms for years. The high rate of mutation makes it impossible for the body to completely eliminate the HIV. Independent of mutation, certain subsets of HIV-recognizing killer T cells are not present or lack optimal function, and there is an inhibition of IFN secretion and cytotoxic T-cell activity due to impairment in the function of CD4+ cells. The HIV is also protected from immune surveillance when it hides within the chromosomes of the infected cells. 

The ABCW relationship is far from exact. There are wide variations in rates of mutation among different loci in the same organism, so the relationship depends somewhat... 

Perhaps it will be possible to counter the effects of an increase in environmental mutagens by lowering the spontaneous-mutation rate (which must be due in part to chemical influences) with exogenous chemicals. It is not likely that a pill that reduces the mutation rate and possibly reduces carcinogenesis as a byproduct and that has no adverse side effects will suddenly appear. But new research has led to much greater knowledge of what controls the rates of mutation. 

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