Bacteria were put on the counter
Bacteria have learned to countDmitry Safin, "Kompyulenta"
A group of specialists from the USA has created artificial gene networks that allow bacteria to count discrete events.
A gene network is usually called a set of consistently expressed genes, their protein products and the relationships between them. Scientists experimented with colonies of E. coli (Escherichia coli) and developed two similar structures that do not occur in this microorganism under natural conditions.
The first gene network, called the "Riboregulated Transcriptional Cascade" (RTC), counts, stopping and starting the processes of transcription and translation of a group of genes when a certain event occurs. The researchers set up the system in such a way that after the third suspension of the processes, the network translates and transcribes a gene encoding a fluorescent protein, the glow of which is recorded in the experiment.
The second configuration of the network, called the "cascade based on DNA invertase" (DNA Invertase Cascade, DIC; DNA invertases are called a special class of enzymes that catalyze the inversion of DNA segments), operates on a different principle. When an event occurs, the first gene in the chain produces a protein that "pulls" this very gene out of the network, "flips" it and inserts it back. In this position, the gene can no longer be transcribed, but an additional DNA fragment attached to it serves as a "marker" indicating that the process can be continued, starting with the next gene. Each such revolution marks an event, and after the third countdown, a fluorescent protein is activated in a similar way.
Each network has its own advantages. RTC can provide a relatively high counting speed (it shows the best results if the interval between events is 20-30 minutes). DIC requires more time to manipulate genes, and therefore long events with long intervals between them are ideal for it (thus the microorganism can count the days, focusing on the change of illumination).
According to the researchers, the counter can be associated with any external events, the influence of which the bacterium is able to feel (for example, it regularly reacts to the presence of certain toxins), as well as with changes in the internal state of the microorganism. The bacterium can be forced to "self-destruct" after the completion of a certain number of cell divisions or after a given time. "It turns out to be a kind of safety mechanism," explains one of the authors of the study, James J. Collins from Boston University. "If you decide to release a microorganism into the environment, intending to use it as a biosensor, or introduce something similar into the patient's body to deliver a drug, you will probably be interested in the possibility of destroying this microorganism after it has done its job."
Both methods, as the authors note, are very promising in terms of modernization and improvement. The most trivial modification, obviously, will be an increase in the capacity of the meter, but many other changes can be made. For example, you can expand the number of genes encoding fluorescent proteins and ensure that different states of the counter will be marked with different shades of glow.
The full version of the report is published in the journal Science.
Prepared based on the materials of Boston University.
Portal "Eternal youth" http://vechnayamolodost.ru/01.06.2009