A strategy for screening an inhibitor of viral silencing suppressors, which attenuates symptom development of plant viruses

To find out whether we can control plant virus diseases by blocking viral RNA silencing suppressors (RSSs), we developed a strategy to screen inhibitors that block the association of RSSs with siRNAs using a surface plasmon resonance assay. The screened chemicals were tested in competition with RSSs for binding to siRNAs using a mobility shift assay. We then confirmed that tested chemicals actually inhibited the RSS activity in vivo using a protoplast assay which was developed for this purpose. This entire system can be adapted to screening inhibitors of not only plant viruses but also some animal viruses possessing RSSs.     

Micropropagation of Cypripedium macranthos var. rebunense through Protocorm-like Bodies Derived from Mature Seeds

Cypripedium macranthos var. rebunense is the most famous terrestrial orchid in Japan, since the variety has large beautiful yellowish-white flowers and is threatened with extinction. Establishment of an efficient method for micropropagation is urgently needed. When imbibed mature seeds of the orchid, that had been pre-chilled at 4°C for 3 months, were sown onto Hyponex-peptone medium that contained both α-naphthaleneacetic acid (NAA) and cytokinin, protocorm-like bodies (PLBs) were formed from germinated seeds. Although the growth of PLBs was very slow, plantlets were easily regenerated from the PLBs on hormone-free medium. The PLBs were subcultured eight times along 2 years without loss of ability to regenerate plantlets, and one aggregate of PLBs (ca. 5 mm in diameter) produced ca. 10 plants within a year. A reduction of commercial value through a large-scale micropropagation by this method will be able to prevent illegal collection from the wild populations.     

Transposable genetic element found in the 5'-flanking region of the fibroin H-chain gene in a genomic clone from the silkworm Bombyx mori

A transposable genetic element was found in the 5'-flanking region of the fibroin H-chain gene in one of the genomic clones from the silkworm Bombyx mori. This element, named K-1.4, is about 1 X 4 X 10(3) base-pairs long, contains an open reading frame of only 225 base-pairs and has inverted repeats of 12 base-pairs at both ends. Duplication of three base-pairs seems to have occurred when this element was integrated into the silkworm genome. About 15 copies of K-1.4 are present per haploid genome of various silkworm strains. Genomic loci of some of these elements are different among different strains or even among individual offspring of the same parents. K-1.4 is present also in the genome of Bombyx mandarina. The K-1.4-related sequences are present in some species belonging to the family Saturniidae.     

Some properties of transmission lines composed of random networks

This paper discusses some properties of a nerve-axon-like transmission line made up from random networks of threshold elements. A random network contains a large number of threshold elements of which the threshold values are Gaussian random variables, and it can act as a monostable or a bistable multivibrator. The signal wave propagation in a transmission line is analyzed by a statistical method. The results show that a signal wave can propagate along the line and that its waveform is shaped, during propagation, into a specific form peculiar to the line. A self-oscillatory system that consists of two random networks is also analyzed. Even in this simple system, various modes of oscillation can exist, with periods varying over a wide range according to the values of system parameters. Examples of self-oscillations obtained by a graphical method are presented, and also some results of computer experiments are shown.