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Diffuse reflectance FTIR spectroscopy was applied to the study of the fundamental C-O bond stretching vibrations and their first overtones and combination modes of copper carbonyl species formed upon CO adsorption on aqueous ion-exchanged CuZSM-5, CuM, CuY, and CuL zeolites autoreduced at 673 K in vacuo and on Cu(I)Y (sse) zeolite prepared by solid-state ion exchange of NH 4 Y with CuCl. At low CO pressures, different kinds of Cu(I)(CO) monocarbonyl species are formed depending upon the types of the zeolites. With increasing the CO pressure, Cu(I)(CO) 2 dicarbonyl species are formed on CuZSM-5, CuM, and CuY. After an evacuation of the preadsorbed CO at room temperature, the dicarbonyl species are transformed into monocarbonyl species. Such a transformation is reversible upon a change of the CO pressure. On the CuL zeolite, however, only one type of monocarbonyl is observed, no dicarbonyl species being detected even at high CO pressures. The frequency of the stretching vibration of the metal cation-carbon bond, i.e., Cu(I)-C bond, in the monocarbonyl species, which is difficult to detect directly by infrared measurements, can be calculated using the corresponding frequencies of the fundamental C-O bond stretching vibration and combination mode. It has been found that this frequency is much more sensitive to the electron donoracceptor ability of the Cu(I) cation in the monocarbonyl species than that of the fundamental C-O stretching vibration alone. On all of the zeolites except CuL, the monocarbonyl species characterized by the frequencies of fundamental C-O and Cu(I)-C bond stretching vibrations of 2157 and ∼440 cm -1 is observed. Another type of monocarbonyl species with its frequencies of fundamental C-O and Cu(I)-C bond stretching vibrations of about 2143 and 500 cm -1 is only formed on the high silica containing zeolites, CuZSM-5 and CuM. The Cu(I) cation in this type of monocarbonyl species possesses a very high electron donor-acceptor ability. On CuY, CuL, and CuZSM-5 (with a low copper loading) one more type of Cu(I) cations with a low electron donor-acceptor ability is detected by the CO probe. Those cations are able to form monocarbonyl species characterized by the lowest frequency of Cu(I)-C bond stretching vibration ranging within 390∼420 cm -1 .

BackgroundInfestation of the phytotoxic aphid Schizaphis graminum can rapidly induce leaf chlorosis in susceptible plants, but this effect is not observed with the nonphytotoxic aphid Sitobion avenae. However, few studies have attempted to identify the different defence responses induced in wheat by S. graminum and S. avenae feeding and the mechanisms underlying the activation of chlorosis by S. graminum feeding.ResultsS. graminum feeding significantly reduced the chlorophyll content of wheat leaves, and these effects were not observed with S. avenae. A transcriptomic analysis showed that the expression levels of genes involved in the salicylic acid, jasmonic acid and ethylene signalling defence pathways were significantly upregulated by both S. avenae and S. graminum feeding; however, more plant defence genes were activated by S. graminum feeding than S. avenae feeding. The transcript levels of genes encoding cell wall-modifying proteins were significantly increased after S. graminum feeding, but only a few of these genes were induced by S. avenae. Furthermore, various reactive oxygen species-scavenging genes, such as 66 peroxidase (POD) and 8 ascorbate peroxidase (APx) genes, were significantly upregulated after S. graminum feeding, whereas only 15 POD and one APx genes were induced by S. avenae feeding. The activity of four antioxidant enzymes was also significantly upregulated by S. graminum feeding. Cytological examination showed that S. graminum feeding induced substantial hydrogen peroxide (H2O2) accumulation in wheat leaves. The chlorosis symptoms and the loss of chlorophyll observed in wheat leaves after S. graminum feeding were reduced and inhibited by the scavenging of H2O2 by dimethylthiourea, which indicated that H2O2 plays important role in the induction of chlorosis by S. graminum feeding.ConclusionsS. graminum and S. avenae feeding induces the JA, SA and ET signalling pathways, but S. graminum activated stronger plant defence responses than S. avenae. S. graminum feeding triggers strong ROS-scavenging activity and massive H2O2 production in wheat leaves, and the accumulation of H2O2 induced by S. graminum feeding is involved in the activation of chlorosis in wheat leaves. These results enhance our understanding of mechanisms underlying aphid-wheat interactions and provide clues for the development of aphid-resistant wheat varieties.

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A novel archaeal virus, denoted ellipsoid virus 1 (SEV1), was isolated from an acidic hot spring in Costa Rica. The morphologically unique virion of SEV1 contains a protein capsid with 16 regularly spaced striations and an 11-nm-thick envelope. The capsid exhibits an unusual architecture in which the viral DNA, probably in the form of a nucleoprotein filament, wraps around the longitudinal axis of the virion in a plane to form a multilayered disk-like structure with a central hole, and 16 of these structures are stacked to generate a spool-like capsid. SEV1 harbors a linear double-stranded DNA genome of ∼23 kb, which encodes 38 predicted open reading frames (ORFs). Among the few ORFs with a putative function is a gene encoding a protein-primed DNA polymerase. Six-fold symmetrical virus-associated pyramids (VAPs) appear on the surface of the SEV1-infected cells, which are ruptured to allow the formation of a hexagonal opening and subsequent release of the progeny virus particles. Notably, the SEV1 virions acquire the lipid membrane in the cytoplasm of the host cell. The lipid composition of the viral envelope correlates with that of the cell membrane. These results suggest the use of a unique mechanism by SEV1 in membrane biogenesis. Investigation of archaeal viruses has greatly expanded our knowledge of the virosphere and its role in the evolution of life. Here we show that ellipsoid virus 1 (SEV1), an archaeal virus isolated from a hot spring in Costa Rica, exhibits a novel viral shape and an unusual capsid architecture. The SEV1 DNA wraps multiple times in a plane around the longitudinal axis of the virion to form a disk-like structure, and 16 of these structures are stacked to generate a spool-like capsid. The virus acquires its envelope intracellularly and exits the host cell by creating a hexagonal hole on the host cell surface. These results shed significant light on the diversity of viral morphogenesis.

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