Development and characterization of a chimaeric tissue-specific promoter in wheat and rice endosperm

The recently achieved significant improvement of cereal transformation protocols provides facilities to alter the protein composition of the endosperm, for example, to increase or decrease the quantity of one of its protein components or to express foreign molecules. To achieve this goal, strong endosperm-specific promoters have to be available. The aim of our work was to develop a more efficient tissue-specific promoter which is currently used. A chimaeric promoter was assembled using the 5' UTR (1,900 bp) of the gene coding for the 1Bx17 HMW glutenin subunit protein, responsible for tissue-specific expression and the first intron of the rice actin gene (act1). The sequence around of the translation initial codon was optimized. The effect of the intron and promoter regulatory sequences, using different lengths of 1Bx17 HMW-GS promoter, were studied on the expression of uidA gene. The function of promoter elements, promoter length, and the first intron of the rice actin gene were tested by a transient expression assay in immature wheat endosperm and in stable transgenic rice plants. Results showed that insertion of the rice act1 first intron increased GUS expression by four times in transient assay. The shortest 1Bx17 HMW-GS promoter fragment (173 bp) linked to the intron and GUS reporter gene provided almost the same expression level than the intronless long 1Bx17 HMW-GS promoter. Analysis of the stable transformant plants revealed that 173 nucleotides were sufficient for endosperm-specific expression of the uidA gene, despite 13 nucleotides missing from the HMW enhancer sequence, a relevant regulatory element in the promoter region

Attosecond coupled electron and nuclear dynamics in dissociative ionization of H-2

The interaction of an extreme-ultraviolet attosecond pulse with a molecular system suddenly removes electrons, which can lead to significant changes in the chemical bonding and hence to rearrangements of the residual molecular cation. The timescales of the electronic and nuclear dynamics are usually very different, thus supporting separate treatment. However, when light nuclei are involved, as in most organic and biological molecules containing atomic hydrogen, the correlation between electronic and nuclear motion cannot be ignored. Using an advanced attosecond pump–probe spectroscopic method, we show that the coupling between electronic and nuclear motion in H2leaves a clear trace in the phase of the entangled electron–nuclear wave packet. This requires us to re-evaluate the physical meaning of the measured phase, which depends on the energy distribution between electrons and nuclei. The conclusions are supported by ab initio calculations that explicitly account for the coupling between electronic and nuclear dynamics