A sixth DNA base has been identified by researchers, adding to the five that were known to occur in the natural world. An international team of investigators recognized the new building block of genetic code and described its function in algae, insects and worms.
A chemical process known as methylation can modify DNA, radically altering the expression of genes in living organisms. The four bases in animal DNA are adenine, thymine, cytosine and guanine, while RNA contains uracil in the place of thymine. Methylated cytosine was traditionally viewed as the main DNA modification found in eukaryotes — cells with a true neucleus and organelles wrapped in a membrane.
An adenine DNA methylation, N6-methyladenine (6mA), has now been identified in algae, flies and worms that assist in regulating cellular function.
“Genes that have methylated cytosine have been associated with reduced gene expression. What’s different about adenine methylation is that it is associated with more strongly expressed genes. It’s a missing piece in the puzzle of regulation at the DNA modification level, and that’s an exciting thing,” said Laurens Mets, associate professor in molecular genetics and cell biology at the University of Chicago.
Epigenetics, the study of chemical reactions that guide genetic expression in living beings, reveals traits can sometimes be passed from parent to offspring without modifying genetic instructions.
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