We all have a biological clock which controls the periodicity ofmany physiological functions such as blood pressure, body temperature and concentration of hormones. The systems that generate circadian rhythms are called oscillator. Oscillator has been researched fordeepening our knowledge of circadian rhythms,understanding genetic network and signal transfer.

Oscillator is expected to be used for various applications.

Therefore, desired features of oscillator are:

1. Variation in types

2. Feasibility in designing and controlling

However, existing protein oscillator does not satisfy the above requirements.

The first problem of protein oscillator is the small type of the protein. Because the number of repressor proteins and promoters are limited, the variation of protein oscillator is not many.

Another problem of protein oscillator is the component, the protein. Protein requires several steps; transcription and translation, protein modification, folding, and degradation. When we want to construct or control such protein oscillator, we have to genetically engineer to change the transcriptional efficiency, translational efficiency and degradation ability. Therefore, it is difficult to design such gene circuits that can express the repressors periodically.

Fig. 2 Steps of proteins

To satisfy the requirements, we propose the New type of oscillator circuit – RNA oscillator.

　Whereas there are only a few types of proteins that can be used for construction of protein oscillator, many kinds of RNA oscillators can be constructed by changing a few base pair. Therefore, it will allow us to construct a multiple and orthogonal oscillators.

Another advantage is that, although protein has several steps until degradation, RNA has no steps of translation, modification and time-consuming degradation. Therefore, RNA oscillator can be designed and controlled by only changing the transcriptional efficiency and binding ability. It is easy to change the binding ability of RNA because all we have to do is to alter the base pair, and hence change the strength of base pairs binding.

Fig.3 Steps of proteins and RNAs　　　　　　　 　　　　　Fig.4 How to make and control the RNA oscillator

Like this, RNA meets the necessary standards for:

1. Variation in types

2. Feasibility in designing and controlling

Therefore, it can be used for combination with diverse mechanisms. For example, we can change output signals from RNA to other ones such as protein with reporter circuit, and control the oscillation with light sensor.

In this way, the ability to combine with various mechanisms can be used for controlling complex systems such as drug delivery.

We named the E. coli which has this function TwinklE.coli because of its brilliant future.

Fig.5 TwinklE. coli