Arabidopsis TCX8 functions as a senescence modulator by regulating LOX2 expression

TCX8 localizes to nucleus and has transcriptional repression activity. TCX8 binds to the promoter region of LOX2 encoding lipoxygenase, causing JA biosynthesis suppression, and thereby delays plant senescence. Conserved CXC domain-containing proteins are found in most eukaryotes. Eight TCX proteins, which are homologs of animal CXC-Hinge-CXC (CHC) proteins, were identified in Arabidopsis, and three of them, TSO1, TCX2/SOL2 and TCX3/SOL1, have been reported to affect cell-cycle control. TCX8, one of the TCX family proteins, was believed to be a TF but its precise function has not been reported. Yeast two-hybrid screening revealed TCP20, a TF that binds to the promoter of LOX2 encoding lipoxygenase, as a strong candidate for interaction with TCX8. We confirmed that TCX8 directly interacts with TCP20 using in vitro pull-down assay and in vivo BiFC and observed that TCX8, as a TF, localizes to nucleus. Using EMSA and by analyzing phenotypes of TCX8-overexpression lines, we demonstrated that TCX8 regulates the expression of LOX2 by binding to either cis-element of LOX2 promoter to which TCP20 or TCP4 binds, affecting JA biosynthesis, and thereby delaying plant senescence. Our study provides new information about the role of TCX8 in modulating plant senescence through regulating LOX2 expression.

Overexpression of AtBBD1, Arabidopsis Bifunctional Nuclease, Confers Drought Tolerance by Enhancing the Expression of Regulatory Genes in ABA-Mediated Drought Stress Signaling

Drought is the most serious abiotic stress, which significantly reduces crop productivity. The phytohormone ABA plays a pivotal role in regulating stomatal closing upon drought stress. Here, we characterized the physiological function of AtBBD1, which has bifunctional nuclease activity, on drought stress. We found that AtBBD1 localized to the nucleus and cytoplasm, and was expressed strongly in trichomes and stomatal guard cells of leaves, based on promoter:GUS constructs. Expression analyses revealed that AtBBD1 and AtBBD2 are induced early and strongly by ABA and drought, and that AtBBD1 is also strongly responsive to JA. We then compared phenotypes of two AtBBD1-overexpression lines (AtBBD1-OX), single knockout atbbd1, and double knockout atbbd1/atbbd2 plants under drought conditions. We did not observe any phenotypic difference among them under normal growth conditions, while OX lines had greatly enhanced drought tolerance, lower transpirational water loss, and higher proline content than the WT and KOs. Moreover, by measuring seed germination rate and the stomatal aperture after ABA treatment, we found that AtBBD1-OX and atbbd1 plants showed significantly higher and lower ABA-sensitivity, respectively, than the WT. RNA sequencing analysis of AtBBD1-OX and atbbd1 plants under PEG-induced drought stress showed that overexpression of AtBBD1 enhances the expression of key regulatory genes in the ABA-mediated drought signaling cascade, particularly by inducing genes related to ABA biosynthesis, downstream transcription factors, and other regulatory proteins, conferring AtBBD1-OXs with drought tolerance. Taken together, we suggest that AtBBD1 functions as a novel positive regulator of drought responses by enhancing the expression of ABA- and drought stress-responsive genes as well as by increasing proline content.

AtMYB109 negatively regulates stomatal closure under osmotic stress in Arabidopsis thaliana

Osmotic stress, caused by drought, salinity, or PEG (polyethylene glycol), is one of the most important abiotic factors that hinder plant growth and development. In Arabidopsis, more than 100 R2R3-MYB transcription factors (TFs) have been identified, and many of them are involved in the transcriptional regulation of a variety of biological processes related to growth and development, as well as responses to biotic and abiotic stresses. However, the MYB TF involving in both plant development and stress response has rarely been reported. We report here that Arabidopsis AtMYB109, a R2R3-MYB TF, functions as a negative regulator of stomatal closure under osmotic stress as well as of pollen tube elongation. Under PEG-induced osmotic stress, whole leaves of AtMYB109-OXs were intensely wilted, while leaves of the wild-type (WT) and myb109 were weakly affected. Moreover, we confirmed that the wilting in AtMYB109-OXs was more severe than in WT and myb109 under drought conditions, and that after re-watering, WT and myb109 plants promptly recovered, while AtMYB109-OXs failed to survive. In addition, stomatal closure was delayed in the AtMYB109-OXs compared to the WT and myb109. However, proline content and the expression of stress-induced and proline synthesis genes were higher in the overexpression lines than in WT and myb109. Then, we observed that the expression of ICS1, a key gene in SA biosynthesis, was greatly suppressed in AtMYB109-OXs. In addition, we found that AtMYB109 expression gradually increased until the flowers were fully opened and thereafter dramatically decreased during silique development. The pollen tube growth was significantly suppressed in AtMYB109-OXs compared to the WT and myb109. Using EMSA and ChIP-qPCR, we confirmed that AtMYB109 bound to the promoter of RABA4D, a gene encoding a pollen development regulator. Taken together, we suggest the delayed stomatal closing and vulnerable phenotypes in the AtMYB109-OXs under osmotic stress are possibly directly or indirectly associated with a SA-mediated mechanism, and that AtMYB109 suppresses RABA4D that modulates pollen tube growth.

CBSX3-Trxo-2 regulates ROS generation of mitochondrial complex II (succinate dehydrogenase) in Arabidopsis

Despite being toxic at a high concentrations, reactive oxygen species (ROS) play a pivotal role as signaling molecules in responses to stress and regulation of plant development. The mitochondrial electron transport chain (ETC) is the major source of ROS in cells. Although the regulation of ROS in mitochondria has been well elucidated, the protein-protein interaction-based regulation of ETC members has not been well elucidated. In this study, we identified a CBS domain-containing protein, CBSX3, and found that CBSX3 activates o-type thioredoxin (Trx-o2) in mitochondria. In addition, we found that Trx-o2 interacts with SDH1, a subunit of ETC complex II. Knockdown (KD) of CBSX3 revealed anther indehiscence due to deficient lignin deposition caused by insufficient ROS accumulation, and increased expression of genes related to cell cycle and accelerated plant growth. However, in the CBSX3-overexpression plants, ROS accumulation increased, and cell cycle-related gene expression decreased, and thereby plant growth was retarded and leaf size decreased. Moreover, KD of CBSX3 and Trx-o2 conferred resistance to mitochondria ETC inhibitors in terms of ROS release. Taken together, we suggest that CBSX3-Trx-o2 is a ROS generation regulator of mitochondria in plants and plays an important role in regulating plant development and the redox system.

Cytokinin oxidase PpCKX1 plays regulatory roles in development and enhances dehydration and salt tolerance in Physcomitrella patens

PpCKX1 localizes to vacuoles and is dominantly expressed in the stem cells. PpCKX1 regulates developmental changes with increased growth of the rhizoid and enhances dehydration and salt tolerance. Cytokinins (CKs) are plant hormones that regulate plant development as well as many physiological processes, such as cell division, leaf senescence, control of shoot/root ratio, and reproductive competence. Cytokinin oxidases/dehydrogenases (CKXs) control CK concentrations by degradation, and thereby influence plant growth and development. In the moss Physcomitrella patens, an evolutionarily early divergent plant, we identified six putative CKXs that, by phylogenetic analysis, form a monophyletic clade. We also observed that ProPpCKX1:GUS is expressed specifically in the stem cells and surrounding cells and that CKX1 localizes to vacuoles, as indicated by Pro35S:PpCKX1-smGFP. Under normal growth conditions, overexpression of PpCKX1 caused many phenotypic changes at different developmental stages, and we suspected that increased growth of the rhizoid could affect those changes. In addition, we present evidence that the PpCKX1-overexpressor plants show enhanced dehydration and salt stress tolerance. Taken together, we suggest that PpCKX1 plays regulatory roles in development and adaptation to abiotic stresses in this evolutionarily early land plant species.

Occurrence of land-plant-specific glycerol-3-phosphate acyltransferases is essential for cuticle formation and gametophore development in Physcomitrella patens

During the evolution of land plants from aquatic to terrestrial environments, their aerial surfaces were surrounded by cuticle composed of cutin and cuticular waxes to protect them from environmental stresses. Glycerol-3-phosphate acyltransferase (GPAT) harboring bifunctional sn-2 acyltransferase/phosphatase activity produces 2-monoacylglycerol, a precursor for cutin synthesis. Here, we report that bifunctional sn-2 GPATs play roles in cuticle biosynthesis and gametophore development of Physcomitrella patens. Land plant-type cuticle was observed in gametophores but not in protonema. The expression of endoplasmic reticulum-localized PpGPATs was significantly upregulated in gametophores compared with protonema. Floral organ fusion and permeable cuticle phenotypes of Arabidopsis gpat6-2 petals were rescued to the wild type (WT) by the expression of PpGPAT2 or PpGPAT4. Disruption of PpGPAT2 and PpGPAT4 caused a significant reduction of total cutin loads, and a prominent decrease in the levels of palmitic and 10,16-dihydroxydecanoic acids, which are major cutin monomers in gametophores. Δppgpat2 mutants displayed growth retardation, delayed gametophore development, increased cuticular permeability, and reduced tolerance to drought, osmotic and salt stresses compared to the WT. Genome-wide analysis of genes encoding acyltransferase or phosphatase domains suggested that the occurrence of sn-2 GPATs with both domains may be a key event in cuticle biogenesis of land plants.

The novel protein CSAP accelerates leaf senescence and is negatively regulated by SAUL1 in the dark

The chloroplast-localized protein CSAP is an ABA-responsive factor and positively regulates dark-induced senescence. This phenomenon is controlled by SAUL1 in Arabidopsis. We report here that CSAP (Chloroplast-localized Senescence-Associated Protein, AT5G39520) functions as a positive regulator of senescence and is controlled by SAUL1 (Senescence Associated E3 Ubiquitin Ligase 1) in Arabidopsis. CSAP transcript level was gradually increased when senescence was progressed. Under dark conditions, the csap mutant showed delayed leaf senescence and reduced chlorophyll breakdown, but overexpression of CSAP accelerated leaf senescence and expressions of chlorophyll catabolic genes were up-regulated compared to the wild-type (WT). NCED3 and AAO3, which are involved in ABA biosynthesis, also showed higher expression in the overexpression lines than the WT. It is known that the CSAP transcript is increased in the saul1 mutant that shows precocious senescence. In our experiments, we confirmed that CSAP interacts with SAUL1 by the yeast two-hybrid and pull-down assays. In addition, we found that SAUL1 decreases the stability of CSAP in the presence of ABA. Taken together, we suggest that CSAP accelerates leaf senescence in the dark and this process is controlled by SAUL1.

Lon domain-containing protein 1 represses thioredoxin y2 and regulates ROS levels in Arabidopsis chloroplasts

Plant thioredoxins (Trxs) act as antioxidants and function as redox regulators in the chloroplast. Although the regulation of ROS in chloroplasts is well elucidated, the precise regulation mechanism of Trx remains unknown. Here, we characterize a novel chloroplast protein, Lon domain-containing protein 1 (LCP1), which contains only a Lon domain, the precise function of which is not known. We find that LCP1 interacts with Trx-y2 and represses its activity, and that knockdown (KD) of LCP1 causes anther indehiscence due to deficient lignin deposition. In addition, LCP1 KD plants show less ROS accumulation and lower expression of ROS-responsive marker genes than the wild-type plant. Taken together, we suggest that LCP1 directly regulates Trx-y2 and controls H₂ O₂ levels and, thereby, regulates lignin polymerization in the anther endothecium.

The transcription factor γMYB2 acts as a negative regulator of secondary cell wall thickening in anther and stem

Secondary cell wall (SCW) thickening provides the mechanical force for anther dehiscence and plays an important role in the formation of xylem structure. We have previously reported that γMYB2, a MYB coiled-coil protein, directly binds to the P1BS cis-element of the PLA₂-γ promoter and acts as a co-activator of γMYB1 in controlling the expression of PLA₂-γ. In this study, we analyzed morphological phenotypes of the constitutive overexpression (γMYB2-OE) and knock-down (γMYB2-KD) lines of γMYB2. We found that γMYB2 overexpression caused the collapse of the endothecium layer, thereby suppressing anther dehiscence and forming short infertile siliques. The γMYB2-OE also showed less cellulose deposition in the xylem and had a longer primary stem than the wild-type, while γMYB2-KD had greater cellulose accumulation and a shorter primary stem than the wild-type. We demonstrated that the male sterility and the longer primary stem in γMYB2-OE were caused by reduced expression of SCW thickening-related genes. Our results suggest that γMYB2 acts as a negative regulator in controlling the SCW thickening in Arabidopsis.

The novel transcription factor TRP interacts with ZFP5, a trichome initiation-related transcription factor, and negatively regulates trichome initiation through gibberellic acid signaling

The trichome-related protein (TRP) is a novel transcription factor (TF) that negatively regulates trichome initiation-related TFs through gibberellin (GA) signaling. Trichomes, which are outgrowths of leaf epidermal cells, provide the plant with a first line of defense against damage from herbivores and reduce transpiration. The initiation and development of trichomes are regulated by a network of positively or negatively regulating transcription factors (TFs). However, little information is currently available on transcriptional regulation related to trichome formation. Here, we report a novel TF Trichome-Related Protein (TRP) that was observed to negatively regulate the trichome initiation-related TFs through gibberellic acid (GA) signaling. ProTRP:GUS revealed that TRP was only expressed in the trichome. The TRP loss-of-function mutant (trp) had an increased number of trichomes on the flower, cauline leaves, and main inflorescence stems compared to the wild-type. In contrast, TRP overexpression lines (TRP-Ox) exhibited a decreased number of trichomes on cauline leaves and main inflorescence stem following treatment with exogenous GA. Moreover, the expressions of trichome initiation regulators (GIS, GIS2, ZFP8, GL1, and GL3) increased in trp plants but decreased in TRP-Ox lines after GA treatment. TRP was observed to physically interact with ZFP5, a C2H2 TF that controls trichome cell development through GA signaling, both in vivo and in vitro. Based on these results, we suggest that TRP functions upstream of the trichome initiation regulators and represses the binding of ZFP5 to the ZFP8 promoter.

A Preclinical Cadaver Fitting Study of Implantable Biventricular Assist Device - AnyHeart™

A multifunctional, Korean-made artificial heart (AnyHeart™) was developed, and prior to its clinical application, a cadaver-fitting study was performed. The study proposed to determine the optimal cannulation approach, implantation technique and route of the cannula to minimize the organ compression of AnyHeart™. The anatomical feasibility and a variety of surgical techniques were evaluated using ten preserved, human cadavers. Implanting AnyHeart™ with ease is possible using various approaches, including a median sternotomy, and a right or left lateral thoracotomy. The lateral thoracotomy approach is shown to be safe and reproducible, especially in patients who have already undergone an operation that used a median sternotomy. The results of this study will guide improvements in the designs of cannulae and AnyHeart™ for future clinical applications.

Dietary whole and cracked linseed increases the proportion of oleic and α-linolenic acids in adipose tissues and decreases stearoyl-coenzyme A desaturase, acetyl-coenzyme A carboxylase, and fatty acid synthase gene expression in the longissimus thoracis muscle of Yanbian Yellow cattle

We hypothesized that supplementation of linseed in a beef cattle fattening diet would increase PUFA concentrations in intramuscular adipose tissue and depress (), (), and () gene expression by decreasing () expression. Conversely, supplemental linseed would upregulate expression of () and () in muscle of Yanbian Yellow steers. Thirty steers were assigned at random to 3 groups of 10 steers fed either the basal diet (corn grain and corn silage-based commercial concentrate [CON]), the CON diet plus 8% whole linseed (WLS; DM basis), or the CON diet plus 8% cracked linseed (CLS; DM basis) for 6 mo. The WLS and CLS supplements did not affect carcass weight, backfat thickness, or marbling scores ( > 0.10) but increased rib eye area and fat color (more yellow; < 0.05). The WLS and CLS diets decreased the proportions of 16:0 and 18:0 and increased the proportions of 18:1-9, 18:3-3, -9, -11 conjugated linoleic acid, total MUFA, and total PUFA in intramuscular, intermuscular, and subcutaneous adipose tissues. The WLS and CLS diets increased and gene expression whereas the supplements depressed , , , and gene expression in longissimus thoracis muscle, relative to CON muscle, consistent with our hypothesis. Because the WLS and CLS treatments did not affect any measure of carcass adiposity, these results indicated that linseed supplements promoted uptake of dietary lipids while concurrently depressing de novo fatty acid biosynthesis in adipose tissue.

IGF-1 Mediates EphrinB1 Activation in Regulating Tertiary Dentin Formation

Eph receptors belong to a subfamily of receptor tyrosine kinases that are activated by membrane-spanning ligands called ephrins. Previously, we demonstrated that the ephrinB1-EphB2 interaction regulates odontogenic/osteogenic differentiation from dental pulp cells (DPCs) in vitro. The goal of this study was to identify the molecular mechanisms regulated by the EphB2/ephrinB1 system that govern tertiary dentin formation in vitro and in vivo. During tooth development, ephrinB1, and EphB2 were expressed in preodontoblast and odontoblasts at postnatal day 4. EphrinB1 was continuously expressed in odontoblasts and odontoblastic processes until the completion of tooth eruption. In addition, ephrinB1 was expressed in odontoblastic processes 2 wk following tooth injury without pulp exposure, whereas EphB2 was expressed in the center of pulp niches but not odontoblasts. In a model of tooth injury with pulp exposure, ephrinB1 was strongly expressed in odontoblasts 4 wk postinjury. In vitro studies with human and mouse DPCs treated with calcium hydroxide (CH) or mineral trioxide aggregate (MTA) showed an increased expression of insulin-like growth factor 1 (IGF-1). Experiments using several inhibitors of IGF-1 receptor signaling revealed that inhibiting the Ras/Raf-1/MAPK pathway inhibited EphB2 expression, and inhibiting the PI3K/Akt/mTOR pathway specifically inhibited ephrinB1 gene expression. Tooth injury in mice with odontoblast-specific IGF-1 receptor ablation exhibited a reduced tertiary dentin volume, mineral density, and ephrinB1 expression 4 wk following injury. We conclude that the IGF-1/ephrinB1 axis plays significant roles in the early stages of tooth injury. Further research is needed to fully understand the potential of targeting ephrinB1 as a regenerative pulp therapy.

The FBA motif-containing protein AFBA1 acts as a novel positive regulator of ABA response in Arabidopsis

ABA plays a critical role in regulating seed germination and stomatal movement in response to drought stress. Screening ABA-responsive genes led to the identification of a novel Arabidopsis gene encoding a protein which contained a conserved F-box-associated (FBA) domain, subsequently named ABA-responsive FBA domain-containing protein 1 (AFBA1). Expression of ProAFBA1:GUS revealed that this gene was mainly expressed in guard cells. Expression of AFBA1 increased following the application of exogenous ABA and exposure to salt (NaCl) and drought stresses. Seed germination of the loss-of-function mutant (afba1) was insensitive to ABA, salt or mannitol, whereas AFBA1-overexpressing (Ox) seeds were more sensitive to these stresses than the wild-type seeds. The afba1 plants showed decreased drought tolerance, increased water loss rate and ABA-insensitive stomatal movement compared with the wild-type. In contrast, AFBA1-Ox plants exhibited enhanced drought tolerance and a rapid ABA-induced stomatal closure response. The expression of genes encoding serine/threonine protein phosphatases that are known negative regulators of ABA signaling increased in afba1 plants but decreased in AFBA1-Ox plants. AFBA1 was also found to be localized in the nucleus and to interact with an R2R3-type transcription factor, MYB44, leading to the suggestion that it functions in the stabilization of MYB44. Based on these results, we suggest that AFBA1 functions as a novel positive regulator of ABA responses, regulating the expression of genes involved in ABA signal transduction in Arabidopsis through its interaction with positive regulators of ABA signaling including MYB44, and increasing their stability during ABA-mediated responses.

Dietary linseed oil with or without malate increases conjugated linoleic acid and oleic acid in milk fat and and gene expression in mammary gland and milk somatic cells of lactating goats

Supplementary dietary plant oils have the potential to alter milk fatty acid composition in ruminants as a result of changes in the amount and kind of fatty acid precursors. We hypothesized that linseed oil in combination with malate (a key propionate precursor in the rumen) would increase ∆9 unsaturated fatty acids and specific gene expression in somatic cells and mammary glands of lactating goats. Twelve lactating goats were used in a 3 × 3 Latin square design. Treatments included the basal diet (CON), the CON plus 4% linseed oil (LO), and the CON plus 4% linseed oil and 2% -malate (LOM). Relative to CON, the LO and LOM supplements increased the daily intake of palmitic (16:0), stearic (18:0), oleic (18:1-9), linoleic (18:2-6), α-linolenic (18:3-3), and γ-linolenic acids (18:2-6); α-linolenic acid intake was increased over 9-fold, from 6.77 to over 51 g/d ( < 0.02). The LO and LOM supplements increased daily milk yield, milk fat yield, and milk fat percentage ( < 0.05). The LOM supplement also increased milk lactose percentage and daily yield ( = 0.03). Both the LO and LOM supplements increased plasma glucose and total cholesterol and decreased plasma β-hydroxbutyrate concentrations ( = 0.03). The LO and LOM supplements increased concentrations of stearic acid; -vaccenic acid (TVA; 18:1-11); -9, -11 CLA; -10 -12 CLA; and α-linolenic acid in rumen fluid and increased the concentrations of oleic acid; TVA; -9, -11 CLA; -10, -12 CLA; and α-linolenic acid in plasma lipids and milk fat ( < 0.05). Conversely, the LO and LOM supplements decreased short- and medium-chain SFA, including lauric (12:0), myristic (14:0), and palmitic acids, in plasma and milk fat ( < 0.05). Relative mRNA levels for and () gene expression were increased in somatic cells and mammary gland tissue by LO and LOM ( < 0.05). We conclude that the higher intake and ruminal production of stearic acid promoted SCD gene expression in somatic cells and mammary tissue. Furthermore, milk somatic cells are a suitable substitute for documenting treatment effects of dietary oils on gene expression in goat mammary tissue.

Plasmacytoma with Aberrant Expression of Myeloid Markers, T-cell Markers, and Cytokeratin

Plasmacytomas are localized neoplastic proliferations of monoclonal plasma cells. When multifocal, the process is referred to as multiple myeloma. These lesions exhibit a pattern of antigen expression and cytomorphology that usually leads to a ready diagnosis. However, potentially troublesome variations in immunophenotype occur. We describe a case of a plasmacytoma from a patient who presented with sudden onset of pain and a lytic lesion of the left proximal humerus. Hematoxylin and eosin-stained sections showed a lymphoproliferative lesion composed of large lymphoid cells, some with plasmacytoid and immunoblastic features. The lesion also showed significant mitotic activity. Immunohistochemical staining was positive for CD45 (LCA), CD56 (N-CAM), CD43 (MT1), and cytokeratin CAM5.2. There was also clonal staining for λ light chains. In addition, flow cytometric analysis showed positivity for myeloid markers such as CD13, CD33, CD38, and CD138. Significant negative markers include CD20 (L26), CD45RO (UCHL-1), and CD79α. The unusual phenotypic features of this plasmacytoma illustrate potential diagnostic pitfalls. It is important to fully study such lesions to correctly classify them, because this has significant impact on prognosis and management.

A Transcription Factor γMYB1 Binds to the P1BS cis-Element and Activates PLA2-γ Expression with its Co-Activator γMYB2

Phospholipase A2(PLA2) hydrolyzes phospholipid molecules to produce two products that are both precursors of second messengers of signaling pathways and signaling molecules per se.Arabidopsis thaliana PLA2 paralogs (-β,-γ and -δ) play critical roles during pollen development, pollen germination and tube growth. In this study, analysis of the PLA2-γ promoter using a deletion series revealed that the promoter region -153 to -1 is crucial for its pollen specificity. Using a yeast one-hybrid screening assay with the PLA2-γ promoter and an Arabidopsis transcription factor (TF)-only library, we isolated two novel MYB-like TFs belonging to the MYB-CC family, denoted here as γMYB1 and γMYB2. By electrophoretic mobility shift assay, we found that these two TFs bind directly to the P1BS (phosphate starvation response 1-binding sequence)cis-element of the PLA2-γ promoter. γMYB1 alone functioned as a transcriptional activator for PLA2-γ expression, whereas γMYB2 directly interacted with γMYB1 and enhanced its activation. Overexpression of γMYB1 in the mature pollen grain led to increased expression of not only the PLA2-γ gene but also of several genes whose promoters contain the P1BS cis-element and which are involved in the Pi starvation response, phospholipid biosynthesis and sugar synthesis. Based on these results, we suggest that the TF γMYB1 binds to the P1BS cis-element, activates the expression of PLA2-γ with the assistance of its co-activator, γMYB2, and regulates the expression of several target genes involved in many plant metabolic reactions.

Heterologous expression of chloroplast-localized geranylgeranyl pyrophosphate synthase confers fast plant growth, early flowering and increased seed yield

Geranylgeranyl pyrophosphate synthase (GGPS) is a key enzyme for a structurally diverse class of isoprenoid biosynthetic metabolites including gibberellins, carotenoids, chlorophylls and rubber. We expressed a chloroplast-targeted GGPS isolated from sunflower (Helianthus annuus) under control of the cauliflower mosaic virus 35S promoter in tobacco (Nicotiana tabacum). The resulting transgenic tobacco plants expressing heterologous GGPS showed remarkably enhanced growth (an increase in shoot and root biomass and height), early flowering, increased number of seed pods and greater seed yield compared with that of GUS-transgenic lines (control) or wild-type plants. The gibberellin levels in HaGGPS-transgenic plants were higher than those in control plants, indicating that the observed phenotype may result from increased gibberellin content. However, in HaGGPS-transformant tobacco plants, we did not observe the phenotypic defects such as reduced chlorophyll content and greater petiole and stalk length, which were previously reported for transgenic plants expressing gibberellin biosynthetic genes. Fast plant growth was also observed in HaGGPS-expressing Arabidopsis and dandelion plants. The results of this study suggest that GGPS expression in crop plants may yield desirable agronomic traits, including enhanced growth of shoots and roots, early flowering, greater numbers of seed pods and/or higher seed yield. This research has potential applications for fast production of plant biomass that provides commercially valuable biomaterials or bioenergy.

Corrigendum. Platelet-rich plasma for arthroscopic repair of medium to large rotator cuff tears: a randomized controlled trial

Jo CH, Shin JS, Shin WH, Lee SY, Yoon KS, Shin S. Platelet-rich plasma for arthroscopic repair of medium to large rotator cuff tears: a randomized controlled trial. Am J Sports Med. 2015 43(9):2102-2110. (Original DOI: 10.1177/0363546515587081 )

CML10, a variant of calmodulin, modulates ascorbic acid synthesis

Calmodulins (CaMs) regulate numerous Ca(2+) -mediated cellular processes in plants by interacting with their respective downstream effectors. Due to the limited number of CaMs, other calcium sensors modulate the regulation of Ca(2+) -mediated cellular processes that are not managed by CaMs. Of 50 CaM-like (CML) proteins identified in Arabidopsis thaliana, we characterized the function of CML10. Yeast two-hybrid screening revealed phosphomannomutase (PMM) as a putative interaction partner of CML10. In vitro and in vivo interaction assays were performed to analyze the interaction mechanisms of CML10 and PMM. PMM activity and the phenotypes of cml10 knock-down mutants were studied to elucidate the role(s) of the CML10-PMM interaction. PMM interacted specifically with CML10 in the presence of Ca(2+) through its multiple interaction motifs. This interaction promoted the activity of PMM. The phenotypes of cml10 knock-down mutants were more sensitive to stress conditions than wild-type plants, corresponding with the fact that PMM is an enzyme which modulates the biosynthesis of ascorbic acid, an antioxidant. The results of this research demonstrate that a calcium sensor, CML10, which is an evolutionary variant of CaM, modulates the stress responses in Arabidopsis by regulating ascorbic acid production.

Long-term control of diabetes in immunosuppressed nonhuman primates (NHP) by the transplantation of adult porcine islets

Pig islets are an alternative source for islet transplantation to treat type 1 diabetes (T1D), but reproducible curative potential in the pig-to-nonhuman primate (NHP) model has not been demonstrated. Here, we report that pig islet grafts survived and maintained normoglycemia for >6 months in four of five consecutive immunosuppressed NHPs. Pig islets were isolated from designated pathogen-free (DPF) miniature pigs and infused intraportally into streptozotocin-induced diabetic rhesus monkeys under pretreatment with cobra venom factor (CVF), anti-thymocyte globulin (ATG) induction and maintenance with anti-CD154 monoclonal antibody and low-dose sirolimus. Ex vivo expanded autologous regulatory T cells were adoptively transferred in three recipients. Blood glucose levels were promptly normalized in all five monkeys and normoglycemia (90-110 mg/dL) was maintained for >6 months in four cases, the longest currently up to 603 days. Intravenous glucose tolerance tests during the follow-up period showed excellent glucose disposal capacity and porcine C-peptide responses. Adoptive transfer of autologous regulatory T cells was likely to be associated with more stable and durable normoglycemia. Importantly, the recipients showed no serious adverse effects. Taken together, our results confirm the clinical feasibility of pig islet transplantation to treat T1D patients without the need for excessive immunosuppressive therapy.

Association between information provision and decisional conflict in cancer patients

BACKGROUND

In this study, we aimed to identify demographic and clinical variables that correlate with perceived information provision among cancer patients and determine the association of information provision with decisional conflict (DC).

PATIENTS AND METHODS

We enrolled a total of 625 patients with cancer from two Korean hospitals in 2012. We used the European Organization for Research and Treatment of Cancer (EORTC) quality-of-life questionnaire (QLQ-INFO26) to assess patients' perception of the information received from their doctors and the Decisional Conflict Scale (DCS) to assess DC. To identify predictive sociodemographic and clinical variables for adequate information provision, backward selective logistic regression analyses were conducted. In addition, adjusted multivariate logistic regression analyses were carried out to identify clinically meaningful differences of perceived level of information subscales associated with high DC.

RESULTS

More than half of patients with cancer showed insufficient satisfaction with medical information about disease (56%), treatment (73%), other services (83%), and global score (80%). In multiple logistic regression analyses, lower income and education, female, unmarried status, type of cancer with good prognosis, and early stage of treatment process were associated with patients' perception of inadequate information provision. In addition, Information about the medical tests with high DCS values clarity [adjusted odds ratio (aOR), 0.54; 95% confidence interval (CI) 0.30-0.97] and support (aOR, 0.53; 95% CI 0.33-0.85) showed negative significance. For inadequate information perception about treatments and other services, all 5 DCS scales (uncertainty, informed, values clarity, support, and effective decision) were negatively related. Global score of inadequate information provision also showed negative association with high DCS effective decision (aOR, 0.43; 95% CI 0.26-0.71) and DCS uncertainty (aOR, 0.46; 95% CI 0.27-0.77).

CONCLUSION

This study found that inadequate levels of perceived information correlated with several demographic and clinical characteristics. In addition, sufficient perceived information levels may be related to low levels of DC.

Seed-specific expression of seven Arabidopsis promoters

Seeds contain storage compounds, from various carbohydrates to proteins and lipids, which are synthesized during seed development. For the purposes of many plant researches or commercial applications, developing promoter systems expressing specifically in seeds or in particular constituents or tissues/compartments of seeds are indispensable. To screen genes dominantly or specifically expressed in seed tissues, we analyzed Arabidopsis ATH1 microarray data open to the public. Thirty-two candidate genes were selected and their expressions in seed tissues were confirmed by RT-PCR. Finally, seven genes were selected for promoter analysis. The promoters of seven genes were cloned into pBI101 vector and transformed into Arabidopsis to assay histochemical β-glucuronidase (GUS) activity. We found that Pro-at3g03230 promoter drove GUS expression in a chalazal endosperm, Pro-at4g27530:GUS expressed in both chalazal endosperm and embryo, Pro-at4g31830 accelerated GUS expression both in radicle and procambium, Pro-at5g10120 and Pro-at5g16460 drove GUS expression uniquely in embryo, Pro-at5g53100:GUS expressed only in endosperm, and Pro-at5g54000 promoted GUS expression in both embryo and inner integument. These promoters can be used for expressing any genes in specific seed tissues for practical application.

The pharmacokinetics, pharmacodynamics and safety of oral doses of ilaprazole 10, 20 and 40 mg and esomeprazole 40 mg in healthy subjects: a randomised, open-label crossover study

BACKGROUND

Ilaprazole, a proton pump inhibitor (PPI) currently in clinical use, may provide improved acid suppression vs. other PPIs.

AIM

To compare the pharmacodynamic and pharmacokinetic profiles of ilaprazole and esomeprazole.

METHODS

A phase 1, randomised, open-label, single-centre, 4-period crossover study was conducted in 40 healthy volunteers. Ilaprazole 10, 20 or 40 mg or esomeprazole 40 mg was administered once daily for 5 days with ≥5-day washout intervals. Pharmacokinetic blood samples and intragastric pH measurements were collected at scheduled timepoints for 24 h after dosing on Days 1 and 5.

RESULTS

Esomeprazole 40 mg provided significantly better pH control during the initial hours (0-4 h) after a single dose, but ilaprazole (particularly 20 and 40 mg) provided significantly better pH control for the entire 24-h period and during evening and overnight hours after single and multiple doses. Increasing ilaprazole doses resulted in dose-proportional increases in peak plasma concentration and area under the plasma concentration vs. time curve following single and multiple doses. Ilaprazole was safe and generally well tolerated; an unexpectedly high incidence of allergic eye and skin reactions were observed but were not specific to any dosing regimen. Plasma gastrin concentrations did not increase proportionately with increasing ilaprazole dose.

CONCLUSIONS

Ilaprazole provided significantly better pH control over 24 h and during evening and overnight hours compared with esomeprazole in healthy volunteers, which may translate to greater relief of night-time heartburn in the clinical setting for patients with gastric acid-related disorders.

OsMPK3 is a TEY-type rice MAPK in Group C and phosphorylates OsbHLH65, a transcription factor binding to the E-box element

OsMPK3 is a TEY-type rice MAPK belonging to Group C and directly phosphorylates OsbHLH65 in the nucleus. OsMPK3 and OsbHLH65 are induced by biotic stress and defense-related hormones. Mitogen-activated protein kinases (MAPKs) are involved in the majority of signaling pathways that regulate plant development and stress tolerance via the phosphorylation of target molecules. Plant MAPKs are classified into two subtypes, TEY and TDY, according to the TxY (x = E or D) motif in their activation loop, and the TDY motif is unique to plant MAPKs. In rice, 17 MAPKs have been classified into six groups. To date, the functions of many TDY-type rice MAPKs have been characterized, but little is known of the TEY-type MAPKs in Group C and their possible target substrates. In the study reported here, we determined that a TEY-type rice MAPK belonging to subgroup C, named OsMPK3, phosphorylates its substrate OsbHLH65 in the nucleus. Our electrophoresis mobility shift assay results revealed that OsbHLH65 specifically binds to the E-box cis-element, but not to the G-box. Both OsMPK3 and OsbHLH65 were induced by treatments with rice blast (Magnaporthe grisea), brown planthopper (Nilaparvata lugens), and defense-related hormones, such as methyl jasmonic acid and salicylic acid. Our results suggest the possibility that OsMPK3 contributes to the defense signal transduction by phosphorylating the basic helix-loop-helix transcription factor.

Effect of alcohol fermented feed on lactating performance, blood metabolites, milk Fatty Acid profile and cholesterol content in holstein lactating cows

A feeding experiment with 40 lactating Holstein cows and 4 dietary treatments was conducted to investigate supplementation with different levels of alcohol fermented feed to the TMR on lactating performance, blood metabolites, milk fatty acid profile and cholesterol concentration of blood and milk. Forty Holstein lactating cows (106±24 d post-partum; mean±SD) were distributed into four groups and randomly assigned to one of four treatments with each containing 10 cows per treatment. The treatment supplemented with TMR (DM basis) as the control (CON), and CON mixed with alcohol-fermented feeds (AFF) at a level of 5%, 10% and 15% of the TMR as T1, T2 and T3, respectively. Dry matter intake and milk yield were not affected by supplementation of AFF. An increased 4% FCM in the milk occurred in cows fed T3 diet compared with CON, while T1 and T2 diets decreased 4% FCM in a dose dependent manner. Supplementation of AFF increased the concentration of albumin, total protein (TP), ammonia, and high density lipoprotein-cholesterol in serum compared with CON. In contrast, supplementation with AFF clearly decreased concentration of blood urea nitrogen (BUN) and total cholesterol (TC) compare with CON. AFF supplementation increased the proportion of C18:1n9 and C18:2n6 compared to CON. A decrease in the concentration of saturated fatty acid (SFA) for T1, T2 and T3 resulted in an increased unsaturated fatty acid (USFA) to SFA ratio compared to CON. Concentration of cholesterol in milk fat was reduced in proportion to the supplemental level of AFF. Feeding a diet supplemented with a moderate level AFF to lactating cows could be a way to alter the feed efficiency and fatty acid profile of milk by increasing potentially human consumer healthy fatty acid without detrimental effects on feed intake and milk production. A substantially decreased cholesterol proportion in milk induced by supplementation AFF suggests that alcohol fermented feed may improve milk cholesterol levels without any negative effects in lactating cows.

Regulation of jasmonic acid biosynthesis by silicon application during physical injury to Oryza sativa L

We investigated the effects of silicon (Si) application on rice plants (Oryza sativa L.) and its responses in the regulation of jasmonic acid (JA) during wounding stress. Endogenous JA was significantly higher in wounded rice plants than in non-wounded. In contrast, Si treatment significantly reduced JA synthesis as compared to non-Si applications under wounding stress. mRNA expression of O. sativa genes showed down-regulation of lipoxygenase, allene oxide synthase 1, allene oxide synthase 2, 12-oxophytodienoate reductase 3, and allene oxide cyclase upon Si application and wounding stress as compared to non-Si-treated wounded rice plants. The physical injury-induced-oxidative stress was modulated by Si treatments, which resulted in higher catalase, peroxidase, and polyphenol oxidase activities as compared with non-Si-treated plants under wounding stress. The higher Si accumulation in rice plants also reduced the level of lipid peroxidation, which helped the rice plants to protect it from wounding stress. In conclusion, Si accumulation in rice plants mitigated the adverse effects of wounding through regulation of antioxidants and JA.

INCB018424 induces apoptotic cell death through the suppression of pJAK1 in human colon cancer cells

Janus kinase (JAK) is one of the main upstream activators of signal transducers and activators of transcription (STAT) that are constitutively activated in various malignancies and are associated with cell growth, survival, and carcinogenesis. Here, we investigated the role of JAKs in colorectal cancer in order to develop effective therapeutic targets for INCB018424, which is the first JAK1/2 inhibitor to be approved by FDA. After examining the basal expression levels of phospho-JAK1 and phospho-JAK2, we measured the effects of INCB018424 on the phosphorylation of JAK1/2 using western blot analysis. Cell viability was determined using the trypan blue exclusion assay. The cell death mechanism was identified by the activation of caspase 3 using western blot and annexin V staining. The basal levels of phospho-JAK1 and phospho-JAK2 were cancer cell type dependent. Colorectal cancer cell lines that phosphorylate both JAK1 and JAK2 include DLD-1 and RKO. INCB018424 inactivates both JAK1 and JAK2 in DLD-1 cells but inactivates only JAK1 in RKO cells. Cell death was proportional to the inactivation of JAK1 but not JAK2. INCB018424 causes caspase-dependent cell death, which is prevented by treatment with z-VAD. The inhibition of JAK1 phosphorylation seemed sufficient to allow INCB018424-mediated apoptosis. JAK1 is a key molecule that is involved in colon cancer cell survival and the inhibition of JAK1 by INCB01424 results in caspase-dependent apoptosis in colorectal cancer cells. The use of selective JAK1 inhibitors could be an attractive therapy against colorectal cancer, but further clinical investigations are needed to test this possibility.

Change in single cystathionine β-synthase domain-containing protein from a bent to flat conformation upon adenosine monophosphate binding

Cystathionine β-synthase (CBS) domains are small intracellular modules that can act as binding domains for adenosine derivatives, and they may regulate the activity of associated enzymes or other functional domains. Among these, the single CBS domain-containing proteins, CBSXs, from Arabidopsis thaliana, have recently been identified as redox regulators of the thioredoxin system. Here, the crystal structure of CBSX2 in complex with adenosine monophosphate (AMP) is reported at 2.2Å resolution. The structure of dimeric CBSX2 with bound-AMP is shown to be approximately flat, which is in stark contrast to the bent form of apo-CBSXs. This conformational change in quaternary structure is triggered by a local structural change of the unique α5 helix, and by moving each loop P into an open conformation to accommodate incoming ligands. Furthermore, subtle rearrangement of the dimer interface triggers movement of all subunits, and consequently, the bent structure of the CBSX2 dimer becomes a flat structure. This reshaping of the structure upon complex formation with adenosine-containing ligand provides evidence that ligand-induced conformational reorganization of antiparallel CBS domains is an important regulatory mechanism.

An Arabidopsis R2R3-MYB transcription factor, AtMYB20, negatively regulates type 2C serine/threonine protein phosphatases to enhance salt tolerance

We have characterized the function of a plant R2R3-MYB transcription factor, Arabidopsis thaliana MYB20 (AtMYB20). Transgenic plants overexpressing AtMYB20 (AtMYB20-OX) enhanced salt stress tolerance while repression lines (AtMYB20-SRDX) were more vulnerable to NaCl than wild-type plants. Following NaCl treatment, the expressions of ABI1, ABI2 and AtPP2CA, which encode type 2C serine/threonine protein phosphatases (PP2Cs) that act as negative regulators in abscisic acid (ABA) signaling, were suppressed in AtMYB20-OX but induced in AtMYB20-SRDX. The electrophoretic mobility shift assay results revealed that AtMYB20 binds to the promoter regions containing the MYB recognition sequence (TAACTG) and an ACGT core element of ABI1 and AtPP2CA. These findings suggest that AtMYB20 down-regulates the expression of PP2Cs, the negative regulator of ABA signaling, and enhances salt tolerance.

A cystathionine-β-synthase domain-containing protein, CBSX2, regulates endothecial secondary cell wall thickening in anther development

Anther formation and dehiscence are complex pivotal processes in reproductive development. The secondary wall thickening in endothecial cells of the anther is a known prerequisite for successful anther dehiscence. However, many gaps remain in our understanding of the regulatory mechanisms underlying anther dehiscence in planta, including a possible role for jasmonic acid (JA) and H(2)O(2) in secondary wall thickening of endothecial cells. Here, we report that the cystathionine β-synthase domain-containing protein CBSX2 located in the chloroplast plays a critical role in thickening of the secondary cell walls of the endothecium during anther dehiscence in Arabidopsis. A T-DNA insertion mutant of CBSX2 (cbsx2) showed increased secondary wall thickening of endothecial cells and early anther dehiscence. Consistently, overexpression of CBSX2 resulted in anther indehiscence. Exogenous JA application induced secondary wall thickening and caused flower infertility in the cbsx2 mutant, whereas it partially restored fertility in the CBSX2-overexpressing lines lacking the wall thickening. CBSX2 directly modulated thioredoxin (Trx) in chloroplasts, which affected the level of H(2)O(2) and, consequently, expression of the genes involved in secondary cell wall thickening. Our findings have revealed that CBSX2 modulates the H(2)O(2) status, which is linked to the JA response and in turn controls secondary wall thickening of the endothecial cells in anthers for dehiscence to occur.

An Arabidopsis cell growth defect factor-related protein, CRS, promotes plant senescence by increasing the production of hydrogen peroxide

Arabidopsis thaliana Cell Growth Defect factor 1 (Cdf1) has been implicated in promotion of proapoptotic Bax-like cell death via the induction of reactive oxygen species (ROS). Here we report a conserved function of a chloroplast-targeting Cdf-related gene Responsive to Senescence (CRS) using CRS overexpression and loss of function in plants as well as CRS heterologous expression in yeast. CRS expression was strongly induced in senescent leaves, suggesting its main functions during plant senescence. CRS expression in yeast mitochondria increased the ROS level and led to cell death in a manner similar to Cdf1. In whole plants, overexpression of CRS caused the loss of chlorophylls (Chls) and the rapid onset of leaf senescence, while the lack of CRS led to the delay of leaf senescence in a loss-of-function mutant, crs. The higher and lower accumulation of H(2)O(2) was correlated with early and late senescence in CRS-overexpressing and crs mutant plants, respectively. Furthermore, expression of senescence-related marker genes and metacaspase genes was induced in CRS-overexpressing plants in response to dark. Our findings suggest that CRS plays a key role in the leaf senescence process that accompanies H(2)O(2) accumulation resulting in cell death promotion.

Down-regulation of the IbEXP1 gene enhanced storage root development in sweetpotato

The role of an expansin gene (IbEXP1) in the formation of the storage root (SR) was investigated by expression pattern analysis and characterization of IbEXP1-antisense sweetpotato (Ipomoea batatas cv. Yulmi) plants in an attempt to elucidate the molecular mechanism underlying SR development in sweetpotato. The transcript level of IbEXP1 was high in the fibrous root (FR) and petiole at the FR stage, but decreased significantly at the young storage root (YSR) stage. IbEXP1-antisense plants cultured in vitro produced FRs which were both thicker and shorter than those of wild-type (WT) plants. Elongation growth of the epidermal cells was significantly reduced, and metaxylem and cambium cell proliferation was markedly enhanced in the FRs of IbEXP1-antisense plants, resulting in an earlier thickening growth in these plants relative to WT plants. There was a marked reduction in the lignification of the central stele of the FRs of the IbEXP1-antisense plants, suggesting that the FRs of the mutant plants possessed a higher potential than those of WT plants to develop into SRs. IbEXP1-antisense plants cultured in soil produced a larger number of SRs and, consequently, total SR weight per IbEXP1-antisense plant was greater than that per WT plant. These results demonstrate that SR development was accelerated in IbEXP1-antisense plants and suggest that IbEXP1 plays a negative role in the formation of SR by suppressing the proliferation of metaxylem and cambium cells to inhibit the initial thickening growth of SRs. IbEXP1 is the first sweetpotato gene whose role in SR development has been directly identified in soil-grown transgenic sweetpotato plants.

Crystal structure of the single cystathionine β-synthase domain-containing protein CBSX1 from Arabidopsis thaliana

The single cystathionine β-synthase (CBS) pair proteins from Arabidopsis thaliana have been identified as being a redox regulator of the thioredoxin (Trx) system. CBSX1 and CBSX2, which are two of the six Arabidopsis cystathione β-synthase domain-containing proteins that contain only a single CBS pair, have close sequence similarity. Recently, the crystal structure of CBSX2 was determined and a significant portion of the internal region was disordered. In this study, crystal structures of full-length CBSX1 and the internal loop deleted (Δloop) form are reported at resolutions of 2.4 and 2.2Å, respectively. The structures of CBSX1 show that they form anti-parallel dimers along their central twofold axis and have a unique ∼155° bend along the side. This is different from the angle of CBSX2, which is suggestive of the flexible nature of the relative angle between the monomers. The biochemical data that were obtained using the deletion as well as point mutants of CBSX1 confirmed the importance of AMP-ligand binding in terms of enhancing Trx activity.

Constitutive expression of CaRma1H1, a hot pepper ER-localized RING E3 ubiquitin ligase, increases tolerance to drought and salt stresses in transgenic tomato plants

CaRma1H1, an endoplasmic reticulum (ER)-localized hot pepper really interesting new genes (RING) E3 Ub ligase, was previously reported to be a positive regulator of drought stress responses. To address the possibility that CaRma1H1 can be used to improve tolerance to abiotic stress in crop plants, CaRma1H1 was constitutively expressed in transgenic tomato (Solanum lycopersicum) plants. CaRma1H1-overexpressing tomato plants (35S:CaRma1H1) exhibited greatly enhanced tolerance to high-salinity treatments compared with wild-type plants. Leaf chlorophyll and proline contents in CaRma1H1 overexpressors were 4.3- to 8.5-fold and 1.2- to 1.5-fold higher, respectively, than in wild-type plants after 300 mM NaCl treatment. Transgenic cotyledons developed and their roots elongated in the presence of NaCl up to 200 mM. In addition, 35S:CaRma1H1 lines were markedly more tolerant to severe drought stress than were wild-type plants. Detached leaves of CaRma1H1 overexpressors preserved water more efficiently than did wild-type leaves during a rapid dehydration process. The ER chaperone genes LePDIL1, LeBIP1, and LeCNX1 were markedly up-regulated in 35S:CaRma1H1 tomatoes compared with wild-type plants. Therefore, overexpression of CaRma1H1 may enhance tomato plant ER responses to drought stress by effectively removing nonfunctional ubiquitinated proteins. Collectively, constitutive expression of CaRma1H1 in tomatoes conferrred strongly enhanced tolerance to salt- and water-stress. This raises the possibility that CaRma1H1 may be useful for developing abiotic stress-tolerant tomato plants.

KEY MESSAGE

CaRma1H1 increases drought tolerance in transgenic tomato plants.

CBSXs are sensor relay proteins sensing adenosine-containing ligands in Arabidopsis

We recently determined that CBSX proteins, which have only one pair of cystathionine β-synthase (CBS) domains, directly regulate the activation of thioredoxins and thereby control cellular H2O2 levels and modulate both plant development and growth. The Arabidopsis genome contains six CBSXs, and these are localized to different subcellular compartments‑ CBSX1 and CBSX2 in the chloroplast, CBSX3 in the mitochondria, CBSX4 in the cytosol, and CBSX5 and CBSX6 in the endoplasmic reticulum. The CBSXs have been identified in prokaryotes and plants, but not in animals. The considerable differences in length and amino acid sequence between CBSX members may result in variations in protein structure and in their specificity to interact with ligands and/or target proteins. Here, we discuss the possibility that the CBSXs are novel sensor relay proteins that use adenosine-containing molecules as a ligand.

Indirect Estimation of CH4 from Livestock Feeds through TOCs Evaluation

Thirty-five available feeds were fermented in vitro in order to investigate their soluble total organic carbon (TOCs) and methane (CH₄) production rate. A fermentation reactor was designed to capture the CH₄ gas emitted and to collect liquor from the reactor during in vitro fermentation. The results showed that CH₄ production rate greatly varied among feeds with different ingredients. The lowest CH₄-producing feeds were corn gluten feed, brewer’s grain, and orchard grass among the energy, protein, and forage feed groups, respectively. Significant differences (p<0.05) were found in digestibility, soluble total organic carbon (TOCs), and CH₄ emissions among feeds, during 48 h of in vitro fermentation. Digestibility and TOCs was not found to be related due to different fermentation pattern of each but TOCs production was directly proportional to CH₄ production (y = 0.0076x, r² = 0.83). From this in vitro study, TOCs production could be used as an indirect index for estimation of CH₄ emission from feed ingredients.

A novel F-box protein represses endothecial secondary wall thickening for anther dehiscence in Arabidopsis thaliana

In plants, the regulation of protein turnover by the ubiquitin proteasome system (UPS) is a key posttranslational mechanism underlying diverse cellular processes. However, the participation of the UPS in cellular processes involved in anther dehiscence, especially endothecial secondary wall (ESW) thickening, has not been characterized. Here, we report that a novel F-box protein in arabidopsis, designated SAF1 (Secondary wall thickening-Associated F-box 1), negatively regulates ESW thickening in the anther. SAF1 is predominantly expressed in flower tissues and interacts with Arabidopsis-Skp1-like 19 (ASK19). SAF1-overexpressed (Ox) lines showed reduced fertility due to a lack or loss of ESW thickening in the anther and inhibition of the expression of relevant genes, such as IRREGURAR XYLEMs (IRXs) in flowers. These findings suggest that the novel Skp/Cul/F-box (SCF) complex consisting of SAF1 as an F-box protein and ASK19 as a Skp functions in secondary wall thickening of the anther endothecium.

Nonsense-mediated mRNA decay factors, UPF1 and UPF3, contribute to plant defense

In Arabidopsis, the NMD-defective mutants upf1-5 and upf3-1 are characterized by dwarfism, curly leaves and late flowering. These phenotypes are similar to those of mutants showing constitutive pathogenesis-related (PR) gene expression, salicylic acid (SA) accumulation and, subsequently, resistance to pathogens. The disease symptoms of upf1-5 and upf3-1 mutants were observed following infection with the virulent pathogen Pst DC3000 with the aim of determining whether the loss of nonsense-mediated mRNA decay (NMD) is involved in disease resistance. These mutant plants showed not only enhanced resistance to Pst DC3000, but also elevated levels of endogenous SA, PR gene transcripts and WRKY transcripts. UPF1 and UPF3 expression was down-regulated in Pst DC3000-infected Arabidopsis plants, but the expression of various NMD target genes was up-regulated. The expression of 10 defense-related genes was elevated in cycloheximide (CHX)-treated plants. The transcriptional ratios of eight of these 10 defense-related genes in CHX-treated to non-treated plants were lower in NMD-defective mutants than in the wild-type plants. These eight defense-related genes are possibly regulated by the NMD mechanism, and it is clear that an alternatively spliced transcript of WRKY62, which contains a premature termination codon, was regulated by this mechanism. Taken together, our results suggest that UPF1 and UPF3, which are key NMD factors, may act as defense-related regulators associated with plant immunity.

Single cystathionine β-synthase domain-containing proteins modulate development by regulating the thioredoxin system in Arabidopsis

Plant thioredoxins (Trxs) participate in two redox systems found in different cellular compartments: the NADP-Trx system (NTS) in the cytosol and mitochondria and the ferredoxin-Trx system (FTS) in the chloroplast, where they function as redox regulators by regulating the activity of various target enzymes. The identities of the master regulators that maintain cellular homeostasis and modulate timed development through redox regulating systems have remained completely unknown. Here, we show that proteins consisting of a single cystathionine β-synthase (CBS) domain pair stabilize cellular redox homeostasis and modulate plant development via regulation of Trx systems by sensing changes in adenosine-containing ligands. We identified two CBS domain-containing proteins in Arabidopsis thaliana, CBSX1 and CBSX2, which are localized to the chloroplast, where they activate all four Trxs in the FTS. CBSX3 was found to regulate mitochondrial Trx members in the NTS. CBSX1 directly regulates Trxs and thereby controls H(2)O(2) levels and regulates lignin polymerization in the anther endothecium. It also affects plant growth by regulating photosynthesis-related [corrected] enzymes, such as malate dehydrogenase, via homeostatic regulation of Trxs. Based on our findings, we suggest that the CBSX proteins (or a CBS pair) are ubiquitous redox regulators that regulate Trxs in the FTS and NTS to modulate development and maintain homeostasis under conditions that are threatening to the cell.

Rectal culture screening for vancomycin-resistant enterococcus in chronic haemodialysis patients: false-negative rates and duration of colonisation

Infection or colonisation with vancomycin-resistant enterococci (VRE) is common in chronic haemodialysis (HD) patients. However, there is limited information on the duration of VRE colonisation or on the reliability of consecutive negative rectal cultures to determine the clearance of VRE in chronic HD patients. Chronic HD patients from whom VRE was isolated were examined retrospectively. Rectal cultures were collected more than three times, at least one week apart, between 1 June 2003 and 1 March 2010. The results of the sequential VRE cultures and patients' data were analysed. Among 812 patients from whom VRE was isolated, 89 were chronic HD patients and 92 had three consecutive negative cultures. It took 60.7 ± 183.9 and 111.4 ± 155.4 days to collect three consecutive negative cultures in the 83 non-chronic haemodialysis patients and nine chronic HD patients, respectively (P = 0.011). The independent risk factors for more than three negative sequential rectal cultures were glycopeptide usage [odds ratio (OR): 2.155; P = 0.003] and length of hospital stay (OR: 1.009; P = 0.001). After three consecutive negative rectal cultures, two of six chronic HD patients and 10 of 36 non-HD patients were culture positive again. In conclusion, a significant proportion of patients colonised with VRE cannot be detected by three-weekly rectal cultures, and the duration of VRE colonisation in chronic haemodialysis patients tends to be prolonged. These results may be contributing to the continued increase in the prevalence of VRE.

Constitutive expression of CaXTH3, a hot pepper xyloglucan endotransglucosylase/hydrolase, enhanced tolerance to salt and drought stresses without phenotypic defects in tomato plants (Solanum lycopersicum cv. Dotaerang)

The hot pepper xyloglucan endo-trans-gluco-sylase/hydrolase (CaXTH3) gene that was inducible by a broad spectrum of abiotic stresses in hot pepper has been reported to enhance tolerance to drought and high salinity in transgenic Arabidopsis. To assess whether CaXTH3 is a practically useful target gene for improving the stress tolerance of crop plants, we ectopically over-expressed the full-length CaXTH3 cDNA in tomato (Solanum lycopersicum cv. Dotaerang) and found that the 35S:CaXTH3 transgenic tomato plants exhibited a markedly increased tolerance to salt and drought stresses. Transgenic tomato plants exposed to a salt stress of 100 mM NaCl retained the chlorophyll in their leaves and showed normal root elongation. They also remained green and unwithered following exposure to 2 weeks of dehydration. A high proportion of stomatal closures in 35S:CaXTH3 was likely to be conferred by increased cell-wall remodeling activity of CaXTH3 in guard cell, which may reduce transpirational water loss in response to dehydration stress. Despite this increased stress tolerance, the transgenic tomato plants showed no detectable phenotype defects, such as abnormal morphology and growth retardation, under normal growth conditions. These results raise the possibility that CaXTH3 gene is appropriate for application in genetic engineering strategies aimed at improving abiotic stress tolerance in agriculturally and economically valuable crop plants.

Constitutive expression of CaXTH3, a hot pepper xyloglucan endotransglucosylase/hydrolase, enhanced tolerance to salt and drought stresses without phenotypic defects in tomato plants (Solanum lycopersicum cv. Dotaerang)

The hot pepper xyloglucan endo-trans-gluco-sylase/hydrolase (CaXTH3) gene that was inducible by a broad spectrum of abiotic stresses in hot pepper has been reported to enhance tolerance to drought and high salinity in transgenic Arabidopsis. To assess whether CaXTH3 is a practically useful target gene for improving the stress tolerance of crop plants, we ectopically over-expressed the full-length CaXTH3 cDNA in tomato (Solanum lycopersicum cv. Dotaerang) and found that the 35S:CaXTH3 transgenic tomato plants exhibited a markedly increased tolerance to salt and drought stresses. Transgenic tomato plants exposed to a salt stress of 100 mM NaCl retained the chlorophyll in their leaves and showed normal root elongation. They also remained green and unwithered following exposure to 2 weeks of dehydration. A high proportion of stomatal closures in 35S:CaXTH3 was likely to be conferred by increased cell-wall remodeling activity of CaXTH3 in guard cell, which may reduce transpirational water loss in response to dehydration stress. Despite this increased stress tolerance, the transgenic tomato plants showed no detectable phenotype defects, such as abnormal morphology and growth retardation, under normal growth conditions. These results raise the possibility that CaXTH3 gene is appropriate for application in genetic engineering strategies aimed at improving abiotic stress tolerance in agriculturally and economically valuable crop plants.

A stress-responsive caleosin-like protein, AtCLO4, acts as a negative regulator of ABA responses in Arabidopsis

Caleosins or related sequences have been found in a wide range of higher plants. In Arabidopsis, seed-specific caleosins are viewed as oil-body (OB)-associated proteins that possess Ca(2+)-dependent peroxygenase activity and are involved in processes of lipid degradation. Recent experimental evidence suggests that one of the Arabidopsis non-seed caleosins, AtCLO3, is involved in controlling stomatal aperture during the drought response; the roles of the other caleosin-like proteins in Arabidopsis remain largely uncharacterized. We have demonstrated that a novel stress-responsive and OB-associated Ca(2+)-binding caleosin-like protein, AtCLO4, is expressed in non-seed tissues of Arabidopsis, including guard cells, and down-regulated following exposure to exogenous ABA and salt stress. At the seed germination stage, a loss-of-function mutant (atclo4) was hypersensitive to ABA, salt and mannitol stresses, whereas AtCLO4-overexpressing (Ox) lines were more hyposensitive to those stresses than the wild type. In adult stage, atclo4 mutant and AtCLO4-Ox plants showed enhanced and decreased drought tolerance, respectively. Following exposure to exogenous ABA, the expression of key ABA-dependent regulatory genes, such as ABF3 and ABF4, was up-regulated in the atclo4 mutant, while it was down-regulated in AtCLO4-Ox lines. Based on these results, we propose that the OB-associated Ca(2+)-binding AtCLO4 protein acts as a negative regulator of ABA responses in Arabidopsis.

Probing the continuous radio frequency spectrum of water relaxation using a carbon nanotube

We have obtained the continuous radio frequency spectrum of water molecule relaxation using carbon nanotubes (CNT) as a high-speed nanoprobe. Three sets of characteristic time scales are clearly identified. Two sets are attributed to the electric-field-driven polarization of water molecules bound to CNTs and the collective relaxation of water layers in the vicinity of CNTs, respectively. The third set is appreciable only in air, and can be related to triplet oxygen relaxation.

Barley DNA-binding methionine aminopeptidase, which changes the localization from the nucleus to the cytoplasm by low temperature, is involved in freezing tolerance

The polymerase chain reaction-based Mirror Orientation Selection (MOS) method was used to isolate low temperature-induced genes from cold-treated winter barley (Hordeum vulgare L. cv. Dongbori). MOS screening identified a novel methionine (Met) aminopeptidase (MAP) designated as HvMAP. The deduced HvMAP protein was determined to possess an aminopeptidase domain and a nuclear localization signal. An in vitro enzyme assay using recombinant HvMAP protein demonstrated MAP activity. The expression of this gene was induced by low temperature and abscisic acid treatment, and overexpression of this gene conferred stronger freezing tolerance to Arabidopsis transgenic plants as compared to wild-type plants. Interestingly, low temperature treatment changed the localization of HvMAP from the nucleus to the cytoplasm. These findings suggest that HvMAP is a novel MAP that functions in freezing tolerance by facilitating protein maturation.

Endoplasmic reticulum- and Golgi-localized phospholipase A2 plays critical roles in Arabidopsis pollen development and germination

The phospholipase A(2) (PLA(2)) superfamily of lipolytic enzymes is involved in a number of essential biological processes, such as inflammation, development, host defense, and signal transduction. Despite the proven involvement of plant PLA(2)s in many biological functions, including senescence, wounding, elicitor and stress responses, and pathogen defense, relatively little is known about plant PLA(2)s, and their genes essentially remain uncharacterized. We characterized three of four Arabidopsis thaliana PLA(2) paralogs (PLA(2)-β, -γ, and -δ) and found that they (1) are expressed during pollen development, (2) localize to the endoplasmic reticulum and/or Golgi, and (3) play critical roles in pollen development and germination and tube growth. The suppression of PLA(2) using the RNA interference approach resulted in pollen lethality. The inhibition of pollen germination by pharmacological PLA(2) inhibitors was rescued by a lipid signal molecule, lysophosphatidyl ethanolamine. Based on these results, we propose that plant reproduction, in particular, male gametophyte development, requires the activities of the lipid-modifying PLA(2)s that are conserved in other organisms.