Most Escherichia coli overexpression vectors used for recombinant protein production (RPP) depend on organic inducers, for example, sugars or simple conjugates. However, these can be expensive and, sometimes, chemically unstable. To simplify this and to cut the cost of RPP, we have developed vectors controlled by the Escherichia coli nitrate‐responsive NarL transcription activator protein, which use nitrate, a cheap, stable, and abundant inorganic ion, to induce high‐level controlled RPP. We show that target proteins, such as green fluorescent protein, human growth hormone, and single‐chain variable region antibody fragments can be expressed to high levels using our promoter systems. As nitrate levels are high in many commercial fertilizers, we demonstrate that controlled RPP can be achieved using readily available and inexpensive garden products.

The effects of magnetic field intensity on the growth of Niew Khiaw Ngoo ( Oryza sativa var . Glutinosa) tissue culture was studied in order to determine the application to increase germination rate and plant growth in the tissue culture process, reduce time, chemical usage and the costs of tissue culture. As a result, using magnetic fields in combination with tissue culture process could be a good option for plant tissue development. Glutinous rice seeds with good quality characteristics were selected, peeled, sterilized and cultured in Murashige and Skoog (MS) for tissue culturing in 6 groups of glass bottles of which each group contained 30 bottles. Each sample set was cultivated at the same time and placed on the foam based equipped with magnets that generated different magnetic field intensities of 0 (the control), 14, 27, 65, 172, or 343 mT. After three days, each sample was examined for the percentage of germination (GP). Four days later, the rice plants were measured in height, root length, fresh and dry weight. The results showed that the intensity of the magnetic field influenced the growth of glutinous rice culture. The intensity of 14–65 mT could increase rice biomass. The Shoot/Root ratio induced by 65 mT magnetic field strength was the highest (1:2.36). The results showed that the growth rate of shoot was less than root (1:1.53) and their roots grew in the same direction as the control group. In contrast, the strong magnetic field intensity at 343 mT resulted in the highest shoot/root ratio of 1.53:1.

The Escherichia coli NarX/NarL two-component response-regulator system regulates gene expression in response to nitrate ions and the NarL protein is a global transcription factor, which activates transcript initiation at many target promoters. One such target, the E. coli ogt promoter, which controls the expression of an O6-alkylguanine-DNA-alkyltransferase, is dependent on NarL binding to two DNA targets centred at positions −44.5 and −77.5 upstream from the transcript start. Here, we describe ogt promoter derivatives that can be activated solely by NarL binding either at position −44.5 or position −77.5. We show that NarL can also activate the ogt promoter when located at position −67.5. We present data to argue that NarL-dependent activation of transcript initiation at the ogt promoter results from a direct interaction between NarL and a determinant in the C-terminal domain of the RNA polymerase α subunit. Footprinting experiments show that, at the −44.5 promoter, NarL and the C-terminal domain of the RNA polymerase α subunit bind to opposite faces of promoter DNA, suggesting an unusual mechanism of transcription activation. Our work suggests new organisations for activator-dependent transcription at promoters and future applications for biotechnology.

Currently, chemicals are widely used in plant cultivation in many countries, allowing plants to have more roots, grow faster, and increase productivity. This research aimed to study application of permanent magnets (Neodymium Magnets (NM)) to accelerate the growth of plant roots instead of using chemicals for cultivation. Pineapples were planted in liquid media under permanent magnetic flux density (B) of 1-90 mT intensity. Magnetic flux directions were arranged in two forms, either toward or ejected from the plant roots. The result showed that the number of roots of pineapples planted under the magnetic flux was 2 times greater than the control and the length of roots was also 4.5 times greater in length than those without magnetic flux. The roots exposed toward the magnetic flux had about 2 times greater number and length of roots compared to when the magnetic flux direction was ejected from the plant roots. The direction of the magnetic flux influenced the direction of plant root growth significantly.