High-density electron anions in a nanoporous single crystal: [Ca24Al28O64]4+(4e-)

We removed approximately 100% of clathrated oxygen ions from the crystallographic cages in a single crystal of 12CaO.7Al2O3, leading to the formation of high-density (approximately 2 x 10(21) cm-3) electrons highly localized in the cages. The resulting electron forms a structure that we interpret as an F+ center and migrates throughout the crystal by hopping to a neighboring cage with conductivity approximately 100 siemens per centimeter, demonstrating that the encaged electron behaves as an anion. The electron anions couple antiferromagnetically with each other, forming a diamagnetic pair or singlet bipolaron. The resulting [Ca24Al28O64]4+(4e-) may be regarded as a thermally and chemically stable single crystalline "electride."     

Cytokinin oxidase regulates rice grain production

Most agriculturally important traits are regulated by genes known as quantitative trait loci (QTLs) derived from natural allelic variations. We here show that a QTL that increases grain productivity in rice, Gn1a, is a gene for cytokinin oxidase/dehydrogenase (OsCKX2), an enzyme that degrades the phytohormone cytokinin. Reduced expression of OsCKX2 causes cytokinin accumulation in inflorescence meristems and increases the number of reproductive organs, resulting in enhanced grain yield. QTL pyramiding to combine loci for grain number and plant height in the same genetic background generated lines exhibiting both beneficial traits. These results provide a strategy for tailormade crop improvement.     

Co-transmission of <Emphasis Type="Italic">Tomato yellow leaf curl virus</Emphasis> (TYLCV)-Mld and TYLCV-IL by the whitefly <Emphasis Type="Italic">Bemisia tabaci</Emphasis>

The ability of the whitefly Bemisia tabaci to transmit two strains of Tomato yellow leaf curl virus, the Israel and Mild strains, was studied after serial transfers of individual whiteflies that were viruliferous for both strains to tomato plants. After single whiteflies had successive acquisition feedings first on a single plant infected with one strain and then on a plant infected with the other strain, the single whiteflies later transmitted intermittently one, the other, or both strains to the test plants during serial transfers at 1-day intervals. Because both strains were found in the head, abdomen, and legs dissected from whiteflies during the retention period after the two successive acquisition feedings, both strains apparently circulate from midgut cells to salivary glands through the hemolymph.     

Antiallergic tea catechin, (-)-epigallocatechin-3-O-(3-O-methyl)-gallate,suppresses FcepsilonRI expression in human basophilic KU812 cells

We previously found that the O-methylated derivative of (-)-epigallocatechin-3-O-gallate (EGCg), (-)-epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG' '3Me), has potent antiallergic activity. The high-affinity IgE receptor, FcepsilonRI, is found at high levels on basophils and mast cells and plays a key role in a series of acute and chronic human allergic reactions. To understand the mechanism of action for the antiallergic EGCG' '3Me, the effect of EGCG' '3Me on the cell surface expression of FcepsilonRI in human basophilic KU812 cells was examined. Flow cytometric analysis showed that EGCG' '3Me was able to decrease the cell surface expression of FcepsilonRI. Moreover, immunoblot analysis revealed that total cellular expression of the FcepsilonRI alpha chain decreased upon treatment with EGCG' '3Me. FcepsilonRI is a tetrameric structure comprising one alpha chain, one beta chain, and two gamma chains. The level of mRNA production of each subunit in KU812 cells was investigated. EGCG' '3Me reduced FcepsilonRI alpha and gamma mRNA levels. The cross-linkage of FcepsilonRI causes the activation of basophils, which leads to the secretion of inflammatory mediators including histamine. EGCG' '3Me treatment inhibited the FcepsilonRI cross-linking-induced histamine release. These results suggested that EGCG' '3Me can negatively regulate basophil activation through the suppression of FcepsilonRI expression.     

Genetic factors determining varietal differences in characters affecting yield between two rice (Oryza sativa L.) varieties,Koshihikari and IR64

The yield of Koshihikari, a Japanese premium rice variety, is relatively lower than that of modern high yielding varieties. IR64 carries several well-known genes such as GS3, an important gene for grain size, sd-1, a semi-dwarf gene, and NARROW LEAF1 (NAL1), a gene for small, narrow flag leaves. In this study, we used two sets of chromosome segment substitution lines (CSSLs), from Koshihikari and IR64, and attempted to evaluate the genetic factors that cause differences between parents by analyzing the function of chromosome regions affecting a trait (CRATs). For 28 traits, we identified 312 CRATs in the Koshihikari background and 275 in the IR64 background. In these, donor alleles had positive effects in 84 and 103 CRATs, respectively. Among these, the CRAT related to GS3 and those for grain number expanded the potential sink size in Koshihikari, although this did not affect final yield. The combination of CRATs that enhances source ability may increase grain yield. Although the sd-1 gene might improve resistance to lodging, the yield of CSSLs with sd-1 decreased by 28.7 %. These results suggest that the smaller biomass conferred by sd-1 might reduce canopy photosynthesis. In the Koshihikari background, the CRAT related to NAL1 and those located on chr. 6 increased SPAD value but had the opposite effect on leaf size. Two CRATs that were detected on chr. 6 and 7 increased leaf area without any effect on the SPAD value. The combination of these CRATs for area and SPAD value might improve source ability.     

Insecticide screening with isolated nerve preparations for structure-activity relationships

The sciatic nerve-sartorius muscle preparation from the frog, the nerve-muscle preparation from the crayfish, and the abdominal nerve cord preparation from the crayfish have been compared for their sensitivity to various insecticides. The crayfish nerve cord was the most sensitive to insecticides and had a broad spectrum of sensitivity. A method was developed with this preparation to compare a large number of synthetic pyrethroids for their potencies to stimulate and block the nerve which is the primary target site. Both stimulating and blocking actions on the nerve can be assessed with this preparation. Certain pyrethroids are active insecticidally despite their weak nerve action, whereas some other pyrethroids are relatively moderate in killing insects despite their potent nerve action. Thus the new method can be effectively used to establish the true structure-activity relationship of synthetic pyrethroids or any other insecticides acting directly on the nerve.     

Insecticidal activity and microsomal metabolism of biooxidizable lindane analogs

The insecticidal activity of lindane analogs, in which some chlorine atoms were replaced by other groups susceptible to microsomal oxidative metabolism, was determined against mosquitos, house flies, and German cockroaches. When tested with a synergist, piperonyl butoxide, one of the methylthio analogs was as active as lindane, whereas several others were also highly active. By examining the ratio of synergized and unsynergized LD₅₀ values (synergistic ratio value), the highly insecticidal methylthio, methoxy, and methyl analogs appear to undergo metabolic detoxication effectively in house flies. By means of in vitro metabolism experiments using microsomal fraction from house fly abdomen, the methoxy, ethoxy, and methylthio analogs were shown to be metabolized rapidly at similar rates. The synergized insecticidal activities of these compounds against various insect species relate linearly with each other, suggesting that the oxidative degradation is inhibited by the synergist to a similar extent and that the transport process to the site of action is not a limiting factor in determining the relative insecticidal activity.     

Quantitative structure-activity studies of benzoylphenylurea larvicides: I. Effect of substituents at aniline moiety against Chilo suppressalis walker

The larvicidal activity of a series of N-2,6-difluoro- and N-2,6-dichlorobenzoyl-N′-(4-substituted phenyl)ureas against nondiapause larvae of the rice stem borer, Chilo suppressalis Walker, was measured by topical application and oral administration methods under conditions with and without piperonyl butoxide as an inhibitor of oxidative metabolism. The effects of substituents at the anilide moiety on the larvicidal activity were analyzed quantitatively using physicochemical substituent parameters and regression analysis. The results indicate that the oxidative metabolism in the larval body which is favored by electron-donating substituents is significant in determining the activity. The activity, when the metabolic factor is eliminated, is enhanced by electron-with-drawing and hydrophobic substituents and lowered by bulky groups. The inhibitory activity against new cuticle formation of the same series of compounds was also measured using cultured integument of the rice stem borer diapause larva. The comparison of the quantitative analyses between larvicidal and integument-level activities shows that inhibition of cuticular development is the most important factor governing larvicidal activity.     

Inhibitory effects of pesticides on growth and respiration of cultured cells

Effects of various drugs including pesticides on the growth and respiration of cultured cells were evaluated comparatively using cell lines derived from mosquito ovary and subcutaneous mouse tissues. The concentration producing 50% inhibition of cell growth, I₅₀ (M), was determined for each of 42 drugs. Inhibitors of respiration and nucleic acid and protein biosyntheses such as rotenone, piericidin A₁, actinomycin D, and puromycin had very high pI₅₀ values of approximately 8. Except for the compounds known to be uncouplers of oxidative phosphorylation, the drugs suppressed the respiration rate of the cultured cells to various degrees. The pI₅₀ value (and the pEC₁₅₀, 150% enhancement of the control, value for uncouplers) was determined for each compound. By examining the relation of pI₅₀ (and pEC₁₅₀) values between cell growth and respiration, the compounds could be classified into two groups according to their modes of inhibitory action against the cultured cells. One mode relates to the inhibition of energy synthesis and the other, perhaps, to interference with the biosynthesis of biomacromolecules.     

Nerve membrane as a target of pyrethroids

Nerve membrane is one of the most important target sites of pyrethroids. Changes in excitability of nerve fibres caused by allethrin can be satisfactorily accounted for in terms of ionic permeabilities of the membrane. Temperature has a profound effect on the allethrin-induced permeability changes.