From the cutting edge of science: a digest of the journal Science

Last week, a group of Japanese researchers led by Professor Takehiko Kobayashi published in the journal Science the work Abundance of Ribosomal RNA Gene Copies Maintains Genome Integrity, which reveals the mystery of the presence in the genomes of all biological species of numerous copies of rDNA genes encoding ribosomal RNA. Ribosomal RNA is an integral component of the molecular machine that produces proteins in cells. By exposing DNA-damaging factors (ultraviolet radiation and chemical agents) to 4 strains of saccharomyces yeast, whose genomes contain from 20 to 100 copies of rDNA genes, and comparing the number of surviving yeast cells, the researchers found that strains containing fewer copies of rDNA have less ability to survive than high-copy strains. The presence of multiple copies of rDNA genes in living organisms is vital for the preservation of genetic information in its original form. In case of loss of some copies of rDNA genes under the action of DNA-damaging factors, intact copies of these genes are activated, keeping the cell genome unchanged.

In the article Gene Doping and Sport, published in the latest issue of the journal Science, Mark Frankel from the American Association for the Advancement of Science, Oliver Rabin from the World Anti-Doping Agency and Theodore Friedmann from the University of California, San Diego warn against attempts to use gene therapy as doping in sports. According to the authors of the publication, athletes and their coaches may be tempted to use available gene therapy techniques to improve results in Olympic competitions, while the available developments are not yet ready for testing on humans. Gene therapy involves the introduction of new genes into the human body, which should produce therapeutic proteins aimed at healing the patient. The ill-considered use of gene doping can lead to the most serious consequences, up to fatal outcomes. In 2006, a case was recorded when the German coach Thomas Springstein tried to purchase repoxygen, a drug designed to increase the level of erythropoietin (a hormone that stimulates the production of red blood cells). When baboons were injected with a drug similar to repoxygen, the circulatory system of the animals turned out to be so overloaded with an abundance of red blood cells that only bloodletting saved the animals' lives. In another experiment, healthy primates developed an unexpectedly strong immune response to a virus used to deliver a therapeutic gene to animal cells. As a result, the animals had to be euthanized. The authors' concern about the problem of gene doping is also due to the availability of gene therapy developments: Internet sites addressed to athletes are full of ads about how the proposed drug "will change muscles at the genetic level and ... make your genes work." The organizers of the Olympic Games plan to conduct a large-scale screening in the coming weeks (2000 tests!) The blood and urine of athletes who arrived in Vancouver to participate in competitions is an unprecedented anti–doping campaign in the history of the Olympic Games.

In the Regulation of Alternative Splicing by Histone Modifications, researchers from the National Cancer Institute in the USA, led by Tom Misteli, describe the relationship they found between the modification of histones (proteins on which chromosomal DNA is "wound") and alternative splicing. Histones are involved not only in DNA packaging, but also ensure the implementation of most processes related to the functioning of DNA, such as DNA doubling, RNA synthesis and its further transformations. It is known that different proteins can be synthesized along one RNA strand, depending on how the splicing process takes place – the process of cutting and joining fragments of this RNA molecule. Misteli's group was able to demonstrate that the splicing process (and hence the choice of which protein will be synthesized) depends on the modification of histones, i.e. on the nature of the chemical groups attached to these proteins.

In the article Bioethical and Clinical Dilemmas of Direct-to-Consumer Personal Genomic Testing: The Problem of Misattributed Equivalence, published in the journal Science Translational Medicine, Charis Eng and Richard R. Sharp from the Cleveland Clinic and Case Western Reserve University, Ohio, discuss the problems associated with the advantages and disadvantages of commercial genetic testing that has become available recently. Scientists note that the results of DNA diagnostics, carefully carried out in the clinic, often differ greatly from the data obtained using commercial genetic tests, and an incorrect interpretation of the results obtained can damage the health of patients and lead to the most unexpected consequences.

Daria Chervyakova
Portal "Eternal youth" http://vechnayamolodost.ru based on Genomeweb materials: This Week in Science 

08.02.2010