Satoru Iwata

Synthesis of germanium enolate polymers from germylene monomers

Abstract A novel germanium containing polymer, poly(germanium enolate), has been synthesized by the reaction of a divalent germanium compound, germylene, with a cyclic α,β-unsaturated ketone in the presence of a catalytic amount of a lithium compound. The germylene was also copolymerized with a cyclic α,β-unsaturated lactone, affording an unstable polymer having a ketene acetal structure in the main chain. The resulting polymers are the first example having a metal enolate structure as repeating unit.

MIZ1-regulated hydrotropism functions in the growth and survival of Arabidopsis thaliana under natural conditions

BACKGROUND AND AIMS Root hydrotropism is a response to water-potential gradients that makes roots bend towards areas of higher water potential. The gene MIZU-KUSSEI1 (MIZ1) that is essential for hydrotropism in Arabidopsis roots has previously been identified. However, the role of root hydrotropism in plant growth and survival under natural conditions has not yet been proven. This study assessed how hydrotropic response contributes to drought avoidance in nature. METHODS An experimental system was established for the study of Arabidopsis hydrotropism in soil. Characteristics of hydrotropism were analysed by comparing the responses of the miz1 mutant, transgenic plants overexpressing MIZ1 (MIZ1OE) and wild-type plants. KEY RESULTS Wild-type plants developed root systems in regions with higher water potential, whereas the roots of miz1 mutant plants did not show a similar response. This pattern of root distribution induced by hydrotropism was more pronounced in MIZ1OE plants than in wild-type plants. In addition, shoot biomass and the number of plants that survived under drought conditions were much greater in MIZ1OE plants. CONCLUSIONS These results show that hydrotropism plays an important role in root system development in soil and contributes to drought avoidance, which results in a greater yield and plant survival under water-limited conditions. The results also show that MIZ1 overexpression can be used for improving plant productivity in arid areas.

A Platform for Controlled Dual-Drug Delivery to the Retina: Protective Effects against Light-Induced Retinal Damage in Rats

Controlled transscleral co-delivery of two drugs, edaravone (EDV) and unoprostone (UNO), using a platform that comprises a microfabricated reservoir, controlled-release cover, and drug formulations, which are made of photopolymerized poly(ethyleneglycol) dimethacrylates, shows synergistic retinal neuroprotection against light injury in rats when compared with single-drug-loaded devices. The device would offer a safer therapeutic method than intravitreal injections for retinal disease treatments.

Germylenes as Monomers for Polymer Synthesis

Germylenes have been utilized as monomers for polymer synthesis for the first time. The construction of a repeating unit of O—Ge—O, O—Ge—Ge—O, O—Ge—C, and C—Ge—C as well as the formation of polygermane have been achieved on the basis of new concepts of “oxidation-reduction copolymerization” and “ligand substitution polymerization.” The former involves a redox process between a germylene (reduc-tant monomer, Mred) and an oxidant monomer (Mox). The Mox employed are p-benzoquinone derivatives, cyclic α,β-unsaturated ke-tones, and substituted acetylenes. During the copolymerization, the germylene (Mred) is oxidized and the Mox is reduced (“oxidation-reduction copolymerization”). The reaction mechanism between germylenes and p-benzoquinone derivatives has been elucidated as copolymerization proceeding via a biradical propagating species involving a germyl radical and/or a semiquinone radical. This is, to our best knowledge, the first clear-cut evidence for a biradical mechanism in polymerization chemistry. A n...

Protective effects of sustained transscleral unoprostone delivery against retinal degeneration in S334ter rhodopsin mutant rats.

It has been suggested that unoprostone isopropyl (UNO) has potent neuroprotective activity in the retina. The effect of sustained transscleral UNO delivery to the posterior segment of the eye on photoreceptor degeneration was evaluated. UNO was loaded into a device made of poly(ethyleneglycol) dimethacrylate by polydimethylsiloxane mold-based UV-curing. The amount of UNO diffusing from these devices was measured using high-performance liquid chromatography. The polymeric devices that released UNO at 1.8 μg/day were implanted on the sclerae of S334ter rats at postnatal 21 days, and electroretinograms (ERGs) were compared with those of topical application and placebo devices. Retinal thickness was evaluated by histological examination. Western blots of specimens 4 weeks after implantation were performed. ERGs showed that the UNO-loaded device prevented the reduction of ERG amplitudes 2 and 4 weeks after implantation, compared with results using a placebo device or topical application. Histological examination showed that the UNO-loaded device prevented the reduction of retinal thickness, and Western blots of specimens indicated that the UNO-loaded device decreased expression of ERK1/2, phosphorylated ERK1/2, and caspase-3. A device that provided sustained UNO administration protected against retinal degeneration in rhodopsin mutant rats, and thus, may have translational potential as a sustainable method to administer drugs to treat retinitis pigmentosa.