PubMed · 14240416
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C I KADO. 1964. CHENOPODIUM, A SENSITIVE HOST FOR TMV-RNA.. https://doi.org/10.1016/0042-6822(64)90221-1
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Leaf discs of dark-adapted tobacco plants were excited by 2 flashes and kept in darkness at 20 degrees C for various time periods, then thermoluminescence emission was recorded without freezing the sample. The B band at 30 degrees C decreased with a half-time t1/2 approximately 1 min and the AG band at 45 degrees C with a t1/2 approximately 5 min. This corresponds to the decay kinetics of S2/3 in PS II centres in the state S2/3 QB - (B band) or S2/3 QB. Assuming that the 45 degrees C band is an 'afterglow' emission originating from those centres with an oxidized QB on which an electron is back-transferred from stroma reductants through a pathway induced by warming, the theoretical ratio of the B and AG band was compared to that measured experimentally. After 2 or 3 flashes producing mainly S3, the intensity of AG band encompassed several fold that of the B band, because recombining S3 recreated S2 QB AG-emitting centres. In order to confirm that the AG band is governed by the heat-induced activation of a dark QB-reducing pathway rather than by PS II charge recombination, the AG emission was characterized in triazine-resistant Chenopodium album weed biotypes. In these mutants where the QB pocket is altered, the B band is strongly downshifted to 18 degrees C, compared to 32 degrees C in the wild type, whereas the AG band is only downshifted by 3 or 4 degrees C, demonstrating that S2/3 QB - is not the limiting step of the AG emission.
The capsid protein (CP) of Cucumber mosaic virus (CMV) is required for cell-to-cell movement, mediated by the 3a movement protein (MP). Deletion of the C-terminal 33 amino acids of the CMV 3a MP (in the mutant designated 3aDeltaC33 MP) resulted in CP-independent cell-to-cell movement, but not long-distance movement. RNA-binding studies done in vitro using isolated bacterially expressed MP showed that the 3aDeltaC33 MP bound RNA more strongly, with fewer regions sensitive to RNase and formed cooperatively bound complexes at lower ratios of protein : RNA than the wild-type (wt) 3a MP. Analysis of the architecture of the complexes by atomic force microscopy showed that the wt 3a MP formed a single type of complex with RNA, resembling beads on a string. By contrast, the 3aDeltaC33 MP formed several types of complexes, including complexes with virtually no MP bound or thicker layers of MP bound to the RNA. Assays showed that protein-RNA complexes containing high levels of either MP inhibited the infectivity and in vitro translatability of viral RNAs. The 3aDeltaC33 MP inhibited these processes at lower ratios of protein : RNA than the wt 3a MP, consistent with its stronger binding properties. The apparent contradiction between these inhibition data and the CP-independent cell-to-cell movement of CMV expressing the 3aDeltaC33 MP is discussed.
Seven triterpenoid saponins were isolated from the seeds of "kancolla", a sweet variety of Chenopodium quinoa. Their structures were phytolaccagenic acid 3-O-[alpha-L-arabinopyranosyl-(1' '-->3')-beta-D-glucuronopyranosyl]-28-O-beta-D-glucopyranoside, oleanolic acid 3-O-[beta-D-glucopyranosyl-(1''-->3')-alpha-L-arabinopyranosyl]-28-O-beta-D-glucopyranoside, hederagenin 3-O-[beta-D-glucopyranosyl-(1''-->3')-alpha-L-arabinopyranosyl]-28-O-beta-D-glucopyranoside, phytolaccagenic acid 3-O-[beta-D-glucopyranosyl-(1''-->3')-alpha-L-arabinopyranosyl]-28-O-beta-D-glucopyranoside, oleanolic acid 3-O-[beta-D-glucuronopyranosyl]-28-O-beta-D-glucopyranoside, oleanolic acid 3-O-[alpha-L-arabinopyranosyl-(1''-->3')-beta-D-glucuronopyranosyl]-28-O-beta-D-glucopyranoside, and the new compound serjanic acid 3-O-[beta-D-glucopyranosyl-(1''-->3')-alpha-L-arabinopyranosyl]-28-O-beta-D-glucopyranoside (1). The structure of 1 was characterized on the basis of spectroscopic and chemical evidence.