Germination of lettuce (Lactuca sativa) 'Grand Rapids' seeds is regulated by phytochrome. The action of phytochrome includes alterations in the levels of gibberellin (GA) and abscisic acid (ABA). To determine the molecular mechanism of phytochrome regulation of ABA metabolism, we isolated four lettuce cDNAs encoding 9-cis-epoxycarotenoid dioxygenase (biosynthesis; LsNCED1-LsNCED4) and four cDNAs for ABA 8#-hydroxylase (catabolism; LsABA8ox1-LsABA8ox4). Measurements of ABA and its catabolites showed that a decrease in ABA level coincided with a slight increase in the level of the ABA catabolite phaseic acid after red light treatment. Quantitative reverse transcription-polymerase chain reaction analysis indicated that ABA levels are controlled by phytochrome through down-regulation of LsNCED2 and LsNCED4 expression and up-regulation of LsABA8ox4 expression in lettuce seeds. Furthermore, the expression levels of LsNCED4 decreased after GA 1 treatment, whereas the levels of expression of the other two genes were unaffected. The LsNCED4 expression was also down-regulated by red light in lettuce seeds in which GA biosynthesis was suppressed by AMO-1618, a specific GA biosynthesis inhibitor. These results indicate that phytochrome regulation of ABA metabolism is mediated by both GA-dependent and -independent mechanisms. Spatial analysis showed that after red light treatment, the ABA decrease on the hypocotyl side was greater than that on the cotyledon side of lettuce seeds. Moreover, phytochrome-regulated expression of ABA and GA biosynthesis genes was observed on the hypocotyl side, rather than the cotyledon side, suggesting that this regulation occurs near the photoperceptive site.Plants undergo correct morphogenesis by responding to light and adapt to various forms of light. In addition to imbibition, some seeds require light to germinate and are called photoblastic seeds. Photoblastic seeds germinate after irradiation with red light (R; wavelength approximately 600-700 nm), and this effect of R is cancelled by successive irradiation with far-red light (FR; wavelength approximately 700-750 nm). The effects of R and FR are reversible. This type of germination, called photogermination, was discovered by experiments using lettuce (Lactuca sativa) 'Grand Rapids' seeds (Borthwick et al., 1952). The energy from wavelengths of R is mainly required for photosynthesis. This strategy allows survival of small seeds in which storage substances are low, such as the seeds of lettuce, tomato (Solanum lycopersicum), tobacco (Nicotiana tabacum), and Arabidopsis (Arabidopsis thaliana). The typical reversible photoreaction of lettuce seeds allowed Butler et al. (1959) to detect the pigment that acts as the R/FR receptor in extracts from etiolated cotyledons of Brassica rapa and etiolated shoots of Zea mays using differential spectrophotometry, and this photoreceptor was named phytochrome.Many studies to elucidate the mechanisms of photoblastic lettuce seed germination have been carried out for over a half century, including biochemica...
Our classification scheme is not only convenient for clinical application, but also reflects the embryological process responsible for congenital lip sinuses.
SEIJI MIURA, MIKI AOKI, YASUHIKO SAEKI, KENJI OHKUBO, YOSHINAO MISHIMA, and TETSUO MOHRI The effect of Zr on the formation of Nb/Nb 5 Si 3 lamellar microstructure by eutectoid decomposition reaction of Nb 3 Si is investigated. It has been shown that the kinetics of the eutectoid decomposition of high-temperature Nb 3 Si phase into Nb and Nb 5 Si 3 phases are sluggish in the binary Nb-Si system and that they are enhanced by Zr additions. The time-temperature-transformation (TTT) diagram for the decomposition is experimentally determined and the acceleration of the reaction by small Zr addition of 1.5 at. pct is confirmed by comparison with the reported TTT curves of binary and ternary alloys containing Ti. The role of the ternary element on the decomposition kinetics is discussed in terms of crystallographic orientation relationships (ORs) and Zr distribution in the parent Nb 3 Si phase during solidification.
f Recent clinical trials showed a prolonged retention of subinhibitory concentrations of unbound azithromycin in the interstitial fluid of soft tissues despite the fact that azithromycin is extensively distributed in tissues. In these clinical trials, interstitial fluid samples were obtained by using the microdialysis method, and it was established that drug concentrations represent proteinunbound drug concentrations. The present study was designed to measure total azithromycin concentrations in the interstitial fluid of the skin of rats by directly collecting interstitial fluid samples from a pore formed on the skin by a dissolving microneedle array. The total azithromycin concentrations in interstitial fluid of the skin were about 4 to 5 times higher than those in plasma throughout the experimental period, and stasis of the azithromycin concentration in interstitial fluid was observed when the concentration of azithromycin in plasma was at the lower limit of quantification. In addition, the skin/plasma concentration ratio transiently increased after dosing (from 4.3 to 83.1). Our results suggest that azithromycin was trapped inside white blood cells and/or phagocytic cells in not only blood but also interstitial fluid, resulting in a high total azithromycin concentration and the retention of its antimicrobial activity at the primary infection site. The stasis of azithromycin in interstitial fluid and skin would lead to long-lasting pharmacological effects (including those against skin infection) at concentrations exceeding the MIC.
Hesperetin is a natural flavonoid with robust antioxidant properties. Our previous study reported that hesperetin can prevent cataract formation. However, an important consideration regarding hesperetin consumption is the limited bioavailability due to its poor solubility. The present study investigated the anti-cataract effects of α-glucosyl hesperidin in vivo and in vitro using a selenite-induced cataract model. SD rats (age, 13 days) were orally administered PBS (0.2 ml) or α-glucosyl hesperidin (200 mg/kg) on days 0, 1 and 2. Sodium selenite was subcutaneously administered to the rats 4 h after the first oral administration on day 0. Antioxidant levels in the lens and blood were measured on day 6. In vitro, human lens epithelial cells were treated with sodium selenite (10 µM) and/or hesperetin (50 or 100 mM) for 24 h and analyzed for apoptosis markers using sub-G 1 population and Annexin V-FITC/propidium iodide staining and DNA ladder formation. α-glucosyl hesperidin treatment significantly reduced the severity of selenite-induced cataract. The level of antioxidants was significantly reduced in the selenite-treated rats compared with in the controls; however, they were normalized with α-glucosyl hesperidin treatment. In vitro, hesperetin could significantly reduce the number of cells undergoing apoptosis induced by sodium selenite in human lens epithelial cell lines. Overall, oral consumption of α-glucosyl hesperidin could delay the onset of selenite-induced cataract, at least in part by modulating the selenite-induced cell death in lens epithelial cells.
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