Cyanobacteria are very old organisms. They have been on earth for at least 2.5 billion years. They are fascinating for many reasons. Many millions of years ago, they developed the ability to produce energy from sunlight. Photosynthetic mechanisms help them produce oxygen and biomass from CO2 and water. With their ability to produce oxygen, they filled the earth's ‘stuffy' atmosphere with the gas that animals and other breathing organisms require for life. The majority of researchers nowadays assume that a former cyanobacteria representative was incorporated into a larger cell. According to this so-called endosymbiotic theory, this incorporation led to the first plant cells with photosynthetic chloroplasts. "Nowadays, cyanobacteria have become popular research objects because they have a broad spectrum of exotic metabolic pathways," said Hess. They are not only seen as organisms that swallow CO2, some of them can also produce oils and alcohols. And this might make some people immediately think of biodiesel.

"We found that the short RNA fragment binds to the RNA transcript of the gene," said Hess. Since the two DNA sequences are located opposite each other, the two RNAs are also complementary and can therefore pair with each other quite well. However, the double strands thus formed are very instable and are rapidly degraded. This is how the non-coding RNA controls the amount of protein in the cell. "The RNA controls one, if not the most, basic process of life," said Hess highlighting the fact that the RNA consists only of 170 nucleotides.

Another discovery, made in 2007, confirms the huge effect of the small pieces of RNA: Bacteria that are attacked by certain viruses (i.e. bacteriophages) and which survive the attack, incorporate fragments of the viral genome into their own genome. These short sequences are then flanked by DNA from which non-coding RNA is produced. The resulting RNAs therefore have the signature of a certain virus. They form big defence complexes with proteins and serve as probes. If the known virus re-enters the cell, its genetic material binds to the complementary RNA pieces and the complex chops it into pieces. "It resembles an adaptable immune system," said Hess. Some bacterial genomes have large viral sequence batteries that are flanked by non-coding RNAs. It is rather like an immunological archive that can be consulted as soon as a virus attacks the bacteria. "We are now investigating how the viral genome becomes part of this genetic archive when the initial attack occurs," said Hess.

The researchers are also using modern automated systems biology methods, which are currently being established at the Centre for Biosystems Analysis (ZBSA) in Freiburg, to search for more unknown RNAs in the genome of their experimental objects. Initial experiments have already provided the researchers with several hundred different candidates. It is worth noting that about 80 such RNAs are known in the well-known E. coli bacteria. "If bacteria with about 4000 genes also have hundreds of non-coding RNAs, then it can easily be imagined that quite a few things have to be regulated," said Hess. One thing seems quite clear. To reduce the behaviour of a cell to the effect of their proteins increasingly seems to be rather a naïve idea.