Antiplatelet prenylflavonoids from Artocarpus communis

Four flavonoids, dihydroartomunoxanthone (1), artomunoisoxanthone (2), cyclocomunomethonol (3) and artomunoflavanone (4), together with three known compounds, artochamins B (5), D and artocommunol CC (6) were isolated from the cortex of the roots of Artocarpus communis. The structures of 1-4 were determined by spectroscopic methods. The antiplatelet effects of the flavonoids, 1-3, 5 and 6 on human platelet-rich plasma (PRP) were evaluated. Of the compounds tested in human PRP, compounds 1, 5 and 6 showed significant inhibition of secondary aggregation induced by adrenaline. It is concluded that the antiplatelet effect of 1, 5 and 6 is mainly owing to an inhibitory effect on thromboxane formation.     

Real time PCR hybridization for the rapid and specific identification of Francisella tularensis

Tularemia is highly infectious and fatal zoonotic disease caused by Gram negative bacteria Francisella tularensis. The necessity to undergo medical treatment in early phase of illness in humans and possibility of making use of bacterial aerosol by terrorists in an attack create an urgent need to implement a rapid and effective method which enables to identify the agent. In our study two primers FopA F/R and hybridization probes FopA S1/S2 designed from fopA gene sequence, were tested for their potential applicability to identify F. tularensis. In this research 50 strains of F. tularensis were used and the test gave positive results. Reaction specificity was confirmed by using of non-Francisella tularensis bacterial species. The results obtained in the real-time PCR reaction with primers Tul4 F/R and hybridization probes Tul4 S1/S2, designed from tul4 gene, were comparable to the results from previous experiment with fopA - primers set. Investigation of fopA and tul4 primers and hybridization probes properties revealed characteristic Tm (melting temperature) value of the products--61 degrees C and 60 degrees C, respectively. Detection sensitivity was remarkably higher when fopA primers set was used 1 fg/microl, and for tul4 primers set, minimal detectable concentration is 10 fg/microl.     

Phenotypic Plasticity in Photosynthetic Temperature Acclimation among Crop Species with Different Cold Tolerances

While interspecific variation in the temperature response of photosynthesis is well documented, the underlying physiological mechanisms remain unknown. Moreover, mechanisms related to species-dependent differences in photosynthetic temperature acclimation are unclear. We compared photosynthetic temperature acclimation in 11 crop species differing in their cold tolerance, which were grown at 15°C or 30°C. Cold-tolerant species exhibited a large decrease in optimum temperature for the photosynthetic rate at 360 μL L⁻¹ CO₂ concentration [Opt (A₃₆₀)] when growth temperature decreased from 30°C to 15°C, whereas cold-sensitive species were less plastic in Opt (A₃₆₀). Analysis using the C₃ photosynthesis model shows that the limiting step of A₃₆₀ at the optimum temperature differed between cold-tolerant and cold-sensitive species; ribulose 1,5-bisphosphate carboxylation rate was limiting in cold-tolerant species, while ribulose 1,5-bisphosphate regeneration rate was limiting in cold-sensitive species. Alterations in parameters related to photosynthetic temperature acclimation, including the limiting step of A₃₆₀, leaf nitrogen, and Rubisco contents, were more plastic to growth temperature in cold-tolerant species than in cold-sensitive species. These plastic alterations contributed to the noted growth temperature-dependent changes in Opt (A₃₆₀) in cold-tolerant species. Consequently, cold-tolerant species were able to maintain high A₃₆₀ at 15°C or 30°C, whereas cold-sensitive species were not. We conclude that differences in the plasticity of photosynthetic parameters with respect to growth temperature were responsible for the noted interspecific differences in photosynthetic temperature acclimation between cold-tolerant and cold-sensitive species.The temperature dependence of leaf photosynthetic rate shows considerable variation between plant species and with growth temperature (Berry and Björkman, 1980; Cunningham and Read, 2002; Hikosaka et al., 2006). Plants native to low-temperature environments and those grown at low temperatures generally exhibit higher photosynthetic rates at low temperatures and lower optimum temperatures, compared with plants native to high-temperature environments and those grown at high temperatures (Mooney and Billings, 1961; Slatyer, 1977; Berry and Björkman, 1980; Sage, 2002; Salvucci and Crafts-Brandner, 2004b). For example, the optimum temperature for photosynthesis differs between temperate evergreen species and tropical evergreen species (Hill et al., 1988; Read, 1990; Cunningham and Read, 2002). Such differences have been observed even among ecotypes of the same species (Björkman et al., 1975; Pearcy, 1977; Slatyer, 1977).Temperature dependence of the photosynthetic rate has been analyzed using the biochemical model proposed by Farquhar et al. (1980). This model assumes that the photosynthetic rate (A) is limited by either ribulose 1,5-bisphosphate (RuBP) carboxylation (A_c) or RuBP regeneration (A_r). The optimum temperature for photosynthetic rate in C₃ plants is thus potentially determined by (1) the temperature dependence of A_c, (2) the temperature dependence of A_r, or (3) both, at the colimitation point of A_c and A_r (Fig. 1; Farquhar and von Caemmerer, 1982; Hikosaka et al., 2006).Open in a separate windowFigure 1.A scheme illustrating the shift in the optimum temperature for photosynthesis depending on growth temperature. Based on the C₃ photosynthesis model, the A₃₆₀ (white and black circles) is limited by A_c (solid line) or A_r (broken line). The optimum temperature for the photosynthetic rate is potentially determined by temperature dependence of A_c (A), temperature dependence of A_r (B), or the intersection of the temperature dependences of A_c and A_r (C). When the optimum temperature for the photosynthetic rate shifts to a higher temperature, there are also three possibilities determining the optimum temperature: temperature dependence of A_c (D), temperature dependence of A_r (E), or the intersection of the temperature dependences of A_c and A_r (F). Especially in the case that the optimum temperature is determined by the intersection of the temperature dependences of A_c and A_r, the optimum temperature can shift by changes in the balance between A_c and A_r even when the optimum temperatures for these two partial reactions do not change.In many cases, the photosynthetic rate around the optimum temperature is limited by A_c, and thus the temperature dependence of A_c determines the optimum temperature for the photosynthetic rate (Hikosaka et al., 1999, 2006; Yamori et al., 2005, 2006a, 2006b, 2008; Sage and Kubien, 2007; Sage et al., 2008). As the temperature increases above the optimum, A_c is decreased by increases in photorespiration (Berry and Björkman, 1980; Jordan and Ogren, 1984; von Caemmerer, 2000). Furthermore, it has been suggested that the heat-induced deactivation of Rubisco is involved in the decrease in A_c at high temperature (Law and Crafts-Brandner, 1999; Crafts-Brandner and Salvucci, 2000; Salvucci and Crafts-Brandner, 2004a; Yamori et al., 2006b). Numerous previous studies have shown changes in the temperature dependence of A_c with growth temperature (Hikosaka et al., 1999; Bunce, 2000; Yamori et al., 2005). Also, the temperature sensitivity of Rubisco deactivation may differ between plant species (Salvucci and Crafts-Brandner, 2004b) and with growth temperature (Yamori et al., 2006b), which may explain variation in the optimum temperature for photosynthesis (Fig. 1, A and D).A_r is more responsive to temperature than A_c and often limits photosynthesis at low temperatures (Hikosaka et al., 1999, 2006; Sage and Kubien, 2007; Sage et al., 2008). Recently, several researchers indicated that A_r limits the photosynthetic rate at high temperature (Schrader et al., 2004; Wise et al., 2004; Cen and Sage, 2005; Makino and Sage, 2007). They suggested that the deactivation of Rubisco at high temperatures is not the cause of decreased A_c but a result of limitation by A_r. However, it remains unclear whether limitation by A_r is involved in the variation in the optimum temperature for the photosynthetic rate (Fig. 1, B and E).A shift in the optimum temperature for photosynthesis can result from changes in the balance between A_r and A_c, even when the optimum temperatures for these two partial reactions do not change (Fig. 1, C and F; Farquhar and von Caemmerer, 1982). The balance between A_r and A_c has been shown to change depending on growth temperature (Hikosaka et al., 1999; Hikosaka, 2005; Onoda et al., 2005a; Yamori et al., 2005) and often brings about a shift in the colimitation temperature of A_r and A_c. Furthermore, recent studies have shown that plasticity in this balance differs among species or ecotypes (Onoda et al., 2005b; Atkin et al., 2006; Ishikawa et al., 2007). Plasticity in this balance could explain interspecific variation in the plasticity of photosynthetic temperature dependence (Farquhar and von Caemmerer, 1982; Hikosaka et al., 2006), although there has been no evidence in the previous studies that the optimum temperature for photosynthesis occurs at the colimitation point of A_r and A_c.Temperature tolerance differs between species and, with growth temperature, even within species from the same functional group (Long and Woodward, 1989). Bunce (2000) indicated that the temperature dependences of A_r and A_c to growth temperature were different between species from cool and warm climates and that the balance between A_r and A_c was independent of growth temperature for a given plant species. However, it was not clarified what limited the photosynthetic rate or what parameters were important in temperature acclimation of photosynthesis. Recently, we reported that the extent of temperature homeostasis of leaf respiration and photosynthesis, which is assessed as a ratio of rates measured at their respective growth temperatures, differed depending on the extent of the cold tolerance of the species (Yamori et al., 2009b). Therefore, comparisons of several species with different cold tolerances would provide a new insight into interspecific variation of photosynthetic temperature acclimation and their underlying mechanisms. In this study, we selected 11 herbaceous crop species that differ in their cold tolerance (Yamori et al., 2009b) and grew them at two contrasting temperatures, conducting gas-exchange analyses based on the C₃ photosynthesis model (Farquhar et al., 1980). Based on these results, we addressed the following key questions. (1) Does the plasticity in photosynthetic temperature acclimation differ between cold-sensitive and cold-tolerant species? (2) Does the limiting step of photosynthesis at several leaf temperatures differ between plant species and with growth temperature? (3) What determines the optimum temperature for the photosynthetic rate among A_c, A_r, and the intersection of the temperature dependences of A_c and A_r?     

Effect of Artichoke Leaf Extract on Hepatic and Cardiac Oxidative Stress in Rats Fed on High Cholesterol Diet

Hypercholesterolemia and lipid peroxidation play complementary roles in atherosclerosis. Artichoke (Cynara scolymus L., Asteraceae) leaf extract (ALE), rich in antioxidants, has cholesterol-reducing effect. We investigated the effect of ALE on serum and hepatic lipid levels and pro-oxidant–antioxidant balance in the liver and heart of hypercholesterolemic rats. Rats were fed on 4% (w/w) cholesterol and 1% cholic acid (w/w) supplemented diet for 1 month. ALE (1.5 g/kg/day) was given by gavage during the last 2 weeks. High cholesterol (HC) diet caused significant increases in serum and liver cholesterol and triglyceride levels. It increased malondialdehyde (MDA) and diene conjugate (DC) levels in both tissues. Hepatic vitamin E levels and hepatic and cardiac glutathione peroxidase (GSH-Px) activities decreased, but superoxide dismutase and glutathione transferase activities, glutathione, and vitamin C levels remained unchanged due to HC diet. Serum cholesterol and triglyceride levels and ratio of cholesterol to high-density lipoprotein (HDL)-cholesterol decreased in ALE plus HC-treated rats, but liver cholesterol and triglyceride levels remained unchanged. Significant decreases in hepatic and cardiac MDA and DC levels and increases in hepatic vitamin E and GSH-Px activities were observed in ALE-treated hypercholesterolemic rats. Our results indicate that ALE decreases serum lipids and hypercholesterolemia-induced pro-oxidant state in both tissues.     

Identification of aquaporin-5 and lipid rafts in human resting saliva and their release into cevimeline-stimulated saliva

BACKGROUND: It is unknown whether AQP5 and lipid rafts are released into human unstimulated (resting) saliva and saliva in response to secretagogues. METHODS: In order to quantitate the salivary concentration of AQP5, we produced a polyclonal antibody for human AQP5 and developed an enzyme-like immunosorbent assay (ELISA). RESULTS: AQP5 and lipid rafts were identified in human resting saliva. The amount of AQP5 in resting saliva showed a diurnal variation with high levels during waking hours, and an age-related decrease in AQP5 was coincident with the volume of resting saliva. Cevimeline, a muscarinic acetylcholine receptor (mAChR) agonist, induced the release of AQP5 with lipid rafts, amylase, mucin, and lysozyme. Changes in saliva AQP5 levels after cevimeline administration occurred simultaneously with changes in saliva flow rates. Confocal microscopy revealed that AQP5 was located in the apical plasma membrane and showed a diffuse pattern in parotid glands under resting conditions. Following cevimeline administration, AQP5 was predominantly associated with the APM and was localized in the lumen. GENERAL SIGNIFICANCE: AQP5 and lipid rafts were released with salivary proteins from human salivary glands by the stimulation of M3 mAChRs, and that changes in saliva AQP5 levels can be used as an indicator of salivary flow rate and also as a useful index of M3 mAChR agonist's action on human salivary glands.     

Different regulation of leaf respiration between Spinacia oleracea, a sun species, and Alocasia odora, a shade species

Mature leaves of shade species exhibit lower respiratory rates than those of sun species. To elucidate the mechanism underlying different respiratory rates between sun and shade species, we examined respiratory properties of leaves in Spinacia oleracea L., a sun species, and Alocasia odora (Lodd.) Spach, a shade species, with special reference to changes in the respiratory rate throughout the night. In S. oleracea , rates of both CO₂ efflux and O₂ uptake decreased with time during the night, whereas in A. odora both rates were virtually constant at lower levels. The rates of O₂ uptake in S . oleracea increased upon addition of sucrose, and the rates attained were virtually identical throughout the night. However, the addition of an uncoupler [carbonyl cyanide p -(trifluoromethoxy)-phenylhydrazone; FCCP] did not alter the rates. In contrast, the rates of O₂ uptake in A. odora were enhanced by the addition of FCCP, but not by sucrose. The concentrations of carbohydrates in the tissue decreased throughout the night in both species and the ATP/ADP ratio was always greater in A. odora. These results indicate that, in S. oleracea , the availability of respiratory substrate determines the respiratory rate, while the low respiratory rate in A. odora is ascribed to its low demand for ATP.     

Specific reduction of delta-opioid receptor binding in transfected NG108-15 cells.

We have recently identified and sequenced the cDNA for an opioid-binding protein with homologies to cell adhesion molecules (OBCAM) (Schofield, P. R., McFarlard, K. C., Hayflick, J. S., Wilcox, J. N., Cho, T. M., Roy, S., Lee, N. M., Loh, H. H., and Seeburg, P. H. (1989) EMBO J. 8, 489-495). Several lines of evidence using antibodies suggest that OBCAM may play a functional role in NG108-15 neuroblastoma x glioma cells, a useful model system that contains a homogeneous population of delta-opioid receptors. A logical extension of this research is to further test this hypothesis. As part of this study, NG108-15 cells were stably transfected with either sense or antisense sequences of a portion of pROM, the rat cDNA for OBCAM. [3H] Diprenorphine binding was greatly reduced in antisense-transfected cells relative to non-transfected cells. Binding to alpha 2-adrenergic, muscarinic, and insulin receptors was unaffected. These results further support the notion that OBCAM or its analogue is part (or a subunit) of an opioid receptor. Furthermore, our observation of an apparently specific reduction in opioid binding in these transfected cells suggests that they may provide a novel genetic approach for studying regulation of the opioid receptor in this defined cell line.