There are no silent genes, there are whispering ones

Traditionally, it was believed that at any given time, about half of the 25,000 identified human genes are "silent" and are activated only if necessary. However, Andre Ptitsyn, a specialist in biomedicine and computer engineering from the University of Colorado, found that modern technologies do not allow registering extremely low levels of expression of signals of "silent" genes.

In most studies, genes considered inactive are usually excluded from the analysis at the beginning of the work. At the same time, according to the obtained Avian results, genes whose expression level cannot be registered using modern methods demonstrate expression profiles that correlate with the expression of other genes.

Ptitsyn used a computer algorithm based on the physical principle of stochastic resonance, which is used to identify weak signals by searching for persistent patterns when registering stronger signals of other origin.

For example, sounds made by a musical group playing in the distance may be indistinguishable to a person in the room, and a working air conditioner creates a constant and distinguishable noise. When observed for a certain period of time, the rhythm created by the playing group and its absence can be noticed. During the performance of the group, the cumulative noise level in the room is higher at the time of the drum beat, even though the sounds made by the group are practically not audible in the room and the drum beats are lost on the general noise background. Measuring the total background noise in a room for a long time allows you to register the contribution of music.

Ptitsyn applied this principle when assessing the level of gene expression. The diagram of changes in gene expression over time represents an alternation of peaks and troughs occurring according to certain patterns (for example, daytime circadian rhythms). The profile of changes in the expression of inactive genes can be registered due to the fact that it corresponds to the rhythm of changes in the expression of active genes.

Gene expression is measured using microchips, but when analyzing the results, data that is considered background noise or weak signals of unknown origin, previously considered unrelated to gene expression, are usually cut off. Ptitsyn found that these data, which are not taken into account, are a reflection of the expression of inactive, or, as the author called them, "whispering" genes. To do this, he isolated genes considered inactive and studied the profiles of background noise expression overlapping with the expression of active genes, the level of which is reliably known.

The rhythms of changes in the dominant expression of active genes are clearly distinguished from background signals, and the rhythms of increasing and decreasing levels of background signals are coordinated with the activity of other interacting genes, both active and silent, involved in the performance of the same function.

The author hopes that his discovery will help scientists in the development of new microchips for the analysis of gene activity and will help to obtain previously unavailable information. He emphasizes that the fact that the previously ignored half of the genes play a role in the functioning of the human body changes a lot. The activity of these genes is not blocked, but weakened, and despite this, they can have a certain effect on the mechanisms of development of various diseases and aging of the body.

Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily

31.03.2008