RNA-Seq Analysis of the Response of the Halophyte,Mesembryanthemum crystallinum (Ice Plant) to High Salinity

Understanding the molecular mechanisms that convey salt tolerance in plants is a crucial issue for increasing crop yield. The ice plant (Mesembryanthemum crystallinum) is a halophyte that is capable of growing under high salt conditions. For example, the roots of ice plant seedlings continue to grow in 140 mM NaCl, a salt concentration that completely inhibits Arabidopsis thaliana root growth. Identifying the molecular mechanisms responsible for this high level of salt tolerance in a halophyte has the potential of revealing tolerance mechanisms that have been evolutionarily successful. In the present study, deep sequencing (RNAseq) was used to examine gene expression in ice plant roots treated with various concentrations of NaCl. Sequencing resulted in the identification of 53,516 contigs, 10,818 of which were orthologs of Arabidopsis genes. In addition to the expression analysis, a web-based ice plant database was constructed that allows broad public access to the data. The results obtained from an analysis of the RNAseq data were confirmed by RT-qPCR. Novel patterns of gene expression in response to high salinity within 24 hours were identified in the ice plant when the RNAseq data from the ice plant was compared to gene expression data obtained from Arabidopsis plants exposed to high salt. Although ABA responsive genes and a sodium transporter protein (HKT1), are up-regulated and down-regulated respectively in both Arabidopsis and the ice plant; peroxidase genes exhibit opposite responses. The results of this study provide an important first step towards analyzing environmental tolerance mechanisms in a non-model organism and provide a useful dataset for predicting novel gene functions.     

Anti‐inflammatory effects of activated protein C on human dendritic cells

Activated protein C (APC) has an anticoagulant action and plays an important role in blood coagulation homeostasis. In addition to its anticoagulant action, APC is known to have cytoprotective effects, such as anti‐apoptotic action and endothelial barrier protection, on vascular endothelial cells and monocytes. However, the effects of APC on DCs have not been clarified. To investigate the effects of APC on human DCs, monocytes were isolated from peripheral blood and DC differentiation induced with LPS. APC significantly inhibited the production of inflammatory cytokines TNF‐α and IL‐6 during differentiation of immature DCs to mature DCs, but did not inhibit the production of IL‐12 and anti‐inflammatory cytokine IL‐10. Interestingly, treatment with 5 μg/mL, but not 25 μg/mL, of APC significantly enhanced production of IL‐10. In addition, protein C, which is the zymogen of APC, did not affect production of these cytokines. On the other hand, flow cytometric analysis of DC's surface molecules indicated that APC does not significantly affect expression of CD83, a marker of mDC differentiation, and the co‐stimulatory molecules CD40, CD80 and CD86. These results suggest that APC has anti‐inflammatory effects on human DCs and may be effective against some inflammatory diseases in which the pathogenesis involves TNF‐α and/or IL‐6 production.     

Environmental dependence of population dynamics and height growth of a subalpine conifer across its vertical distribution: an approach using high‐resolution aerial photographs

Many studies have reported shifts in the altitudinal ranges of plant species in response to recent global warming. However, most studies of tree species have been conducted on a small scale and have focused on tree line ecotones by examining tree rings and age structure on account of the long life spans of the trees. To examine the impact of climate change on forest dynamics at a regional scale, we investigated differences in the population density and canopy height of a Japanese subalpine coniferous species, Abies mariesii, between 1967 and 2003 by analysis of high‐resolution aerial photographs of the Hakkoda Mountains, Honshu, Japan. In 712 plots within the photographs we analyzed which environmental variables (including elevation, aspect, wetness, and distance from moorlands) account for these changes. The population density of A. mariesii decreased below 1000 m a.s.l. and increased above 1300 m a.s.l. It also increased around moorlands, which may provide refugia at low elevations. The rate of increase in canopy height was lowest on the southeastern slopes and on the periphery of the moorlands. The distinct changes in the population density of A. mariesii at its distribution limits probably reflect the responses of the population to climatic changes during three decades. Areas surrounding the moorlands may offer refugia in spite of the poor growing conditions there.     

Deletion of fucose residues in plant N‐glycans by repression of the GDP‐mannose 4,6‐dehydratase gene using virus‐induced gene silencing and RNA interference

Production of pharmaceutical glycoproteins in plants has many advantages in terms of safety and reduced costs. However, plant‐produced glycoproteins have N‐glycans with plant‐specific sugar residues (core β‐1,2‐xylose and α‐1,3‐fucose) and a Lewis a (Le^a) epitope, i.e., Galβ(1‐3)[Fucα(1‐4)]GlcNAc. Because these sugar residues and glycan structures seemed to be immunogenic, several attempts have been made to delete them by repressing their respective glycosyltransferase genes. However, until date, such deletions have not been successful in completely eliminating the fucose residues. In this study, we simultaneously reduced the plant‐specific core α‐1,3‐fucose and α‐1,4‐fucose residues in the Le^a epitopes by repressing the Guanosine 5′‐diphosphate (GDP)‐D‐mannose 4,6‐dehydratase (GMD) gene, which is associated with GDP‐L‐fucose biosynthesis, in Nicotiana benthamiana plants. Repression of GMD was achieved using virus‐induced gene silencing (VIGS) and RNA interference (RNAi). The proportion of fucose‐free N‐glycans found in total soluble protein from GMD gene‐repressed plants increased by 80% and 95% following VIGS and RNAi, respectively, compared to wild‐type plants. A small amount of putative galactose substitution in N‐glycans from the NbGMD gene‐repressed plants was observed, similar to what has been previously reported GMD‐knockout Arabidopsis mutant. On the other hand, the recombinant mouse granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) with fucose‐deleted N‐glycans was successfully produced in NbGMD‐RNAi transgenic N. benthamiana plants. Thus, repression of the GMD gene is thus very useful for deleting immunogenic total fucose residues and facilitating the production of pharmaceutical glycoproteins in plants.     

The leaf anatomy of a broad-leaved evergreen allows an increase in leaf nitrogen content in winter

In temperate regions, evergreen species are exposed to large seasonal changes in air temperature and irradiance. They change photosynthetic characteristics of leaves responding to such environmental changes. Recent studies have suggested that photosynthetic acclimation is strongly constrained by leaf anatomy such as leaf thickness, mesophyll and chloroplast surface facing the intercellular space, and the chloroplast volume. We studied how these parameters of leaf anatomy are related with photosynthetic seasonal acclimation. We evaluated differential effects of winter and summer irradiance on leaf anatomy and photosynthesis. Using a broad-leaved evergreen Aucuba japonica , we performed a transfer experiment in which irradiance regimes were changed at the beginning of autumn and of spring. We found that a vacant space on mesophyll surface in summer enabled chloroplast volume to increase in winter. The leaf nitrogen and Rubisco content were higher in winter than in summer. They were correlated significantly with chloroplast volume and with chloroplast surface area facing the intercellular space. Thus, summer leaves were thicker than needed to accommodate mesophyll surface chloroplasts at this time of year but this allowed for increases in mesophyll surface chloroplasts in the winter. It appears that summer leaf anatomical characteristics help facilitate photosynthetic acclimation to winter conditions. Photosynthetic capacity and photosynthetic nitrogen use efficiency were lower in winter than in summer but it appears that these reductions were partially compensated by higher Rubisco contents and mesophyll surface chloroplast area in winter foliage.     

Discovery of TAK-960: An orally available small molecule inhibitor of polo-like kinase 1 (PLK1)

Using structure-based drug design, we identified and optimized a novel series of pyrimidodiazepinone PLK1 inhibitors resulting in the selection of the development candidate TAK-960. TAK-960 is currently undergoing Phase I evaluation in adult patients with advanced solid malignancies.     

Inhibition of HIV-1 replication by a tricyclic coumarin GUT-70 in acutely and chronically infected cells

The anti-HIV-1 activity of GUT-70, a natural product derived from the stem bark of Chlophyllum brasiliense, was evaluated. GUT-70 inhibited HIV-1 replication in both acutely and chronically infected cells through suppression of NF-κB. Our results strengthen the idea that NF-κB pathway is one of the potential targets to control HIV-1 replication and that GUT-70 could serve as a lead compound to develop novel therapeutic agents against HIV-1 infection.     

The octadecaneuropeptide ODN prevents 6‐hydroxydopamine‐induced apoptosis of cerebellar granule neurons through a PKC‐MAPK‐dependent pathway

Oxidative stress, induced by various neurodegenerative diseases, initiates a cascade of events leading to apoptosis, and thus plays a critical role in neuronal injury. In this study, we have investigated the potential neuroprotective effect of the octadecaneuropeptide (ODN) on 6‐hydroxydopamine (6‐OHDA)‐induced oxidative stress and apoptosis in cerebellar granule neurons (CGN). ODN, which is produced by astrocytes, is an endogenous ligand for both central‐type benzodiazepine receptors (CBR) and a metabotropic receptor. Incubation of neurons with subnanomolar concentrations of ODN (10^?18 to 10^?12 M) inhibited 6‐OHDA‐evoked cell death in a concentration‐dependent manner. The effect of ODN on neuronal survival was abrogated by the metabotropic receptor antagonist, cyclo_1–8[DLeu⁵]OP, but not by a CBR antagonist. ODN stimulated polyphosphoinositide turnover and ERK phosphorylation in CGN. The protective effect of ODN against 6‐OHDA toxicity involved the phospholipase C/ERK MAPK transduction cascade. 6‐OHDA treatment induced an accumulation of reactive oxygen species, an increase of the expression of the pro‐apoptotic gene Bax, a drop of the mitochondrial membrane potential and a stimulation of caspase‐3 activity. Exposure of 6‐OHDA‐treated cells to ODN blocked all the deleterious effects of the toxin. Taken together, these data demonstrate for the first time that ODN is a neuroprotective agent that prevents 6‐OHDA‐induced oxidative stress and apoptotic cell death.     

Effect of elevated CO<Subscript>2</Subscript> levels on leaf starch,nitrogen and photosynthesis of plants growing at three natural CO<Subscript>2</Subscript> springs in Japan

Plant communities around natural CO₂ springs have been exposed to elevated CO₂ levels over many generations and give us a unique opportunity to investigate the effects of long-term elevated CO₂ levels on wild plants. We searched for natural CO₂ springs in cool temperate climate regions in Japan and found three springs that were suitable for studying long-term responses of plants to elevated levels of CO₂: Ryuzin-numa, Yuno-kawa and Nyuu. At these CO₂ springs, the surrounding air was at high CO₂ concentration with no toxic gas emissions throughout the growth season, and there was natural vegetation around the springs. At each site, high-CO₂ (HC) and low-CO₂ (LC) plots were established, and three dominant species at the shrub layers were used for physiological analyses. Although the microenvironments were different among the springs, dicotyledonous species growing at the HC plots tended to have more starch and less nitrogen per unit dry mass in the leaves than those growing at the LC plots. In contrast, monocotyledonous species growing in the HC and LC plots had similar starch and nitrogen concentrations. Photosynthetic rates at the mean growth CO₂ concentration were higher in HC plants than LC plants, but photosynthetic rates at a common CO₂ concentration were lower in HC plants. Efficiency of water and nitrogen use of leaves at growth CO₂ concentration was greatly increased in HC plants. These results suggest that natural plants growing in elevated CO₂ levels under cool temperate climate conditions have down-regulated their photosynthetic capacity but that they increased photosynthetic rates and resource use efficiencies due to the direct effect of elevated CO₂ concentration.     

Modeling leaf CO2 assimilation and Photosystem II photochemistry from chlorophyll fluorescence and the photochemical reflectance index

We present a simple model to assess the quantum yield of photochemistry (Φ_P) and CO₂ assimilation rate from two parameters that are detectable by remote sensing: chlorophyll (chl) fluorescence and the photochemical reflectance index (PRI). Φ_P is expressed as a simple function of the chl fluorescence yield (Φ_F) and nonphotochemical quenching (NPQ): Φ_P = 1–bΦ_F(1 + NPQ). Because NPQ is known to be related with PRI, Φ_P can be remotely assessed from solar‐induced fluorescence and the PRI. The CO₂ assimilation rate can be assessed from the estimated Φ_P value with either the maximum carboxylation rate (V_cmax), the intercellular CO₂ concentration (C_i), or parameters of the stomatal conductance model. The model was applied to experimental data obtained for Chenopodium album leaves under various environmental conditions and was able to successfully predict Φ_F values and the CO₂ assimilation rate. The present model will improve the accuracy of assessments of gas exchange rates and primary productivity by remote sensing.