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Letter from the editor

DNA tampering

The idea of manipulating DNA to modify the human body is slowly becoming a reality. Researchers from all over the world, including Brazil, are working on methods that could effectively eliminate or alleviate certain diseases. What these scientists want is to silence, alter, or replace the genes that cause problems. Last year, Chinese scientists announced that they had for the first time improved the immune system of a patient with cancer and HIV by deactivating a gene. The results were only partially positive, but the experiment suggests that the procedure is possible, apparently without issue. Other tests on humans are underway, mostly in China and the USA.

The gene-editing tool used is known as Crispr-Cas9. The technique involves cutting DNA in cells at specific points and altering it. As always occurs during scientific breakthroughs, research groups are racing to see who can achieve the best—and safest—results first. A few years ago, early experiments were successful in trying to correct genes in cells, animals, and even human embryos that would later be discarded; now, experimental treatments have begun.

In São Paulo, groups at various universities are using Crispr not only to study the best way to treat diseases, but also to produce animal organs that can be transplanted to people. The aim is to deactivate the genes that trigger the natural defense system, which causes body to reject the organ. A genetically modified pig kidney, for example, could help remove a patient from the transplant queue.

Crispr is the star of the moment, but it is not the only tool available. An especially curious case in the US has had repercussions in Brazil and indicates that there is still much to be learned and overcome. A biotechnology company altered the genome of a bull so that its descendants are born without horns. This type of cattle is in high demand in the dairy industry because they are easier to manage, among other reasons. The researchers used the Talen technique, through which a plasmid—a DNA molecule of bacterial origin—is used to alter the genome. The bull has since fathered two male calves. A Brazilian company even started the process of importing semen from one of the genetically altered bulls, until tests showed that the plasmid DNA had been incorporated into the animal’s genome, something that was unexpected and highly undesirable.


The wildfires that occur in Australia every year are predictable and natural, unlike those that devastate the Amazon. The abnormally high number of fires that started in Australian territory in September 2019, many of which have not yet been extinguished, are seen by some climatologists as a consequence of climate extremes caused by global warming. Thelma Krug, a Brazilian mathematician who is one of the three vice presidents of the Intergovernmental Panel on Climate Change (IPCC), warns that the panel’s next report is expected to include new scientific studies showing with a high degree of confidence that many extreme events are attributable to climate change.