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Revolutionary Discovery in GeneticsThe scientists are still baffled |
By Vlad Tarko, Senior Editor, Sci-Tech News
12th of January 2006, 09:36 GMT
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For more than a century, one fundamental idea of genetic theory has been that an organism's genome passes directly from one generation to the next: from grandparents, to parents, to children.
However, Susan Lolle, Robert Pruitt and their colleagues from Purdue University have shown this rule of inheritance is sometimes broken. The scientists reached their conclusion by tracking how genetic information passes through multiple generations of the model plant, Arabidopsis thaliana. In violation of current genetic theory, they found a significant percentage of the plant grandchildren had genetic information identical to that of the grandparent, but not the parent - the "missing" genetic information unexpectedly reappears in later generations.
But how could the child acquire genetic information from its grandparent, if the parent had lost it? Lolle and Pruitt postulate that the "lost" genetic information securely resides outside the standard genome and is only retrieved under particular circumstances when it may be beneficial to restore genomic
sequences back to an ancestral state. So, the information was not lost, but rather "hidden"-from scientists anyway.
It is possible that cells have a method for keeping an additional backup copy of the precious information as RNA or maybe even a way of reverse engineering the DNA Sequence from the produced proteins. DNA produces proteins, but, maybe, in certain conditions proteins can also produce DNA.
The scientists have cartographed 100% of the Human DNA and many other organisms. But there is still a much larger set of proteins to be categorized and mapped. It is widely unknown which information they share or even their exact functions.
There are still other possibilities: There are certain correction mechanisms working in a cell - mechanisms preventing mutations. It may be that grandparent's DNA isn't necessarily stored somewhere but, nevertheless, such mechanisms manage to recover or recreate the old DNA (the grandparent's) because the new one isn't that good. Some scientists speculate that such an error correction system may store its checksums in the so-called Junk-DNA (another word for "I have no idea what that's for").
Lolle said, "This ancestral information acts like a reserve genetic template that plants can make use of should living conditions become less ideal. In this way, we think plants get a 'second chance' to win the genetic lottery."
"This means that inheritance can happen more flexibly than we thought in the past," said Pruitt. "While Mendel's laws that we learned in high school still are fundamentally correct, they're not absolute. If the inheritance mechanism we found in the research plant Arabidopsis exists in animals, too, it's possible that it will be an avenue for gene therapy to treat or cure diseases in both plants and animals."
For a long time, Lolle was skeptical of her own results and hesitant to believe something so novel could be occurring. For years she tried to find some trivial explanations for what she was seeing. Eventually, Lolle could no longer discount the evidence, so she meticulously repeated the experiments and verified the results, ruling out all explanations afforded by conventional dogma. The data became irrefutable: the genetic information is indeed sometimes "skipping" a generation. The results were published by Nature in March, last year.
This is a truly revolutionary finding having implications that still puzzle scientists. As Rita Teutonico, the National Science Foundation program manager who oversaw this work said, "We knew the project was ambitious, but these results challenge us to re-think some genetic paradigms and demonstrate that some very forward thinking ideas warrant investigation."
UPDATE: The same phenomenon was observed in mice: Scientists Find Mice that Brake Mendel's Law
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