酵素工学
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概要

The impact nutragenetics versus the central dogma of molecular biology

Levi Ezequiel de Oliveira

Nutrigenetics, which is ruled by epigenetic mechanisms, specifically studies the modifying effects of inheritance. At the molecular level, what happens is that DNA sequence can be expressed or silenced by epigenetic information, which is directly influenced by environmental conditions. This information system (DNA sequence) is used by the organisms as described by the central dogma of molecular Biology stated by James Watson, co-discoverer of the DNA structure in 1959. This hypothesis predicts that information flows in a single direction from our DNA sequence to RNA through a process called transcription and from RNA to proteins through a process called translation. However, there is another layer of information beyond DNA sequence. From the decade of 1970, a new set of research in genetics gathered in a branch of science called epigenetics (beyond genetic) showed solid evidences that the phenotype is not controlled only by DNA sequence. Environmental conditions will also influence the phenotype by determining regions of DNA sequence that needs to be silenced or expressed. So, there are two types of information that will be used to build a protein. One is the DNA sequence itself and the other will determine what part of DNA sequence will be used by the cell. The influence of epigenetic mechanism is so profound that it can even alter the DNA sequence, since methylation is mutagenic. Methylated cytosine is prone to deamination to thymine. CpG dinucleotides are under-represented in vertebrate genomes. Moreover, the different amount of CpG among organisms shows a solid evidence that methylation also plays an important role in evolution. The difference between the mutagenic effect of methylation and the other types of mutation, which are random, is that the methylation tends to be directional and influenced by environmental conditions.