New discovery: The plant Arabidopsis uses a genetic backup copy to repair a damaged gene. It is possible that a similar mechanism exists in humans * Some argue that the species threatens to shatter the principles of genetics
Photo: Pedro University
Geneticists from Purdue University in the USA claim to have discovered plants that, even though they have a defective gene inherited from both of their "parents", possess a modified version of the gene - as if it had been preserved from earlier generations. This startling discovery suggests that some organisms have a secret backup copy of their genome that bypasses the normal mechanism of inheritance. If this hypothesis is confirmed, it will - in an unprecedented way - contradict the laws of heredity, as formulated by Gregor Mendel in the 19th century.
Another surprising finding is that the backup copy is not made of DNA, but of a substance close to it - RNA. A German evolutionary researcher, who wrote a critical article on the study, claims that there are signs that point to the possibility that a similar mechanism also exists in humans.
The latest discovery also raises interesting questions from the field of biology: one of them is whether the finding is consistent with the theory of evolution, according to which the organism changes through mutations - and is not corrected by a genetic backup system. "This looks like an amazing discovery," said Dr. Eliot Meyerovich from the "California Institute of Technology". Dr. David Haig, an evolutionary biologist from Harvard University, claims that "these are really strange and unexpected results". According to him, the finding will be of great importance if it turns out that this is a phenomenon that is a natural law.
The discovery, described in the journal "Nature" by the authors of the article - Dr. Robert Pruitt, Dr. Susan Lowell and their colleagues at Purdue University - was found in only one species of plant called Arabidopsis - a mustard-like plant that is used as the standard laboratory plant in plant genetic research. However, in an article criticizing the study, authored by Dr. Detlef Weigel from the "Max Planck Institute for Biological Evolution" in Tübingen, Germany, it is claimed that there are signs that point to the possibility that a similar mechanism also exists in humans.
The findings were discovered as part of a research project that began three years ago, and was designed to test the action of the genes responsible for the formation of the plant's outer skin layer. As part of the project, plants with a genetic mutation that causes the petals of the plant to stick to each other were studied. According to the laws of genetics, since both copies of the plant's genetic pool were mutated, there was no chance of it having normal "offspring". Despite this, about 10% of the progeny developed normally (with their petals separated).
"This is the least crazy hypothesis"
There are hypotheses about some rare events that could have occurred and explain the phenomenon, but none of them are related to changing the DNA units of the gene. However, when the researchers analyzed the mutated gene, they discovered that it had indeed changed, and the DNA units of the mutated plant returned to their normal state. "It was a moment of complete shock," said Dr. Pruitt.
There are several known mechanisms that are able to repair a mutated gene, but all of them need a normal copy of the gene that can be used as a template for repair. The Purdue University team scanned the entire genome of the Arabidopsis plant in search of a second secret copy of the gene, known as the "Hothead", and found nothing. Dr. Pruitt and his colleagues claim that there must be a corrected copy, but since it does not appear in the form of DNA, it is probably made of RNA - a chemical substance close to DNA.
RNA has many roles in cell function and is the genetic material from which some viruses are made. However, it is considered a less stable substance than DNA, so it was assumed that it is not suitable for keeping the genetic code of higher organisms. Dr. Pruitt believes in the idea that there is a backup copy made of RNA for the entire genome and not just for this specific gene, and that the copy may come into action when the plant is in distress - such as in the case when one of its genes has mutated. He and his colleagues explained that it is possible that the RNA backup copy exists, even if it has not been discovered until today, simply because there was no reason to look for it until now.
Papers that present innovative scientific ideas are usually reviewed for months or years by the respected scientific journals. However, in this case "Nature" received the article in only six weeks. Biology editor at Nature, Dr. Christopher Surridge, said the idea had been debated at scientific conferences for some time, drawing much opposition from researchers who argued that it was impossible and that there must be another explanation. However, the authors of the article checked all the possibilities and refuted them, Surridge explained. And as for the idea of backing up the genome's RNA, Surridge said: "It may be a hypothesis, but in general it is the least crazy hypothesis."
The editor's note of the science site
The editor of the website adds: Plants are generally more forgiving of mutations than animals, and this is also the reason for their greater diversity compared to animals, so it is possible that the discovery contradicts the laws of genetics, although this does not mean that it contradicts Darwin's theory of evolution, on Although there will be those who claim that this is a 'Marxist' inheritance. It should be noted that Darwin noticed differences between descendants of the same species and said that this was the source of the creation of new species, but he did not insist on the depth of the laws of inheritance that were discovered at about the same time by Gregor Mendel, but due to historical circumstances, they were not known throughout the scientific world of that time (see Bridge to a passage from the book the monk in the garden).
Nature is probably more diverse than it is commonly thought, and in the end even extreme cases are integrated into science which eventually reaches the status quo, even if they contradict at first there is a way to combine them and only in extreme cases is an entire Torah replaced.
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