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.

Single cystathionine ß-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 ß-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.

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.

A cystathionine-ß-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 ß-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.

Usability study of a smart transfer-assistive robot with dual arms for care workers.

PURPOSE: The predicted global labor shortages and health problems for long-term care workers can be addressed by care robots. We have developed a smart transfer-assistive robot with dual arms to assist in patient transfers. This study aims to evaluate the effectiveness and usability of a transfer-assistive robot with dual arms for long-term care workers in the Living Lab of Kyung Hee University. METHODS: Long-term care workers (N = 15) transferred healthy adults using the transfer-assistive robot and subsequently reported the workload differences of manual care and the transfer-assistive robot, as measured by the Borg rating of the perceived exertion scale (RPE) and the NASA Task Load Index (NASA-TLX). They also completed questionnaires on the usability of transfer-assistive robots and open-ended interviews. The RPE and NASA-TLX values for each task were compared using the Wilcoxon signed-rank test, and descriptive statistics were used to calculate demographics and usability. RESULTS: The RPE scale indicated that the perceived physical burden was significantly reduced when using the transfer-assistive robot compared with the manual method. The robot-aided transfer method significantly reduced the physical demand in the NASA-TLX subscales. In the usability test, the averages for safety, operability, and satisfaction were all three points or higher, indicating a positive result. CONCLUSION: This study demonstrates that a transfer-assistive robot has the potential to reduce physical stress and the risk of work-related musculoskeletal disorders in long-term care workers. This study shows that the robot is effective for long-term care workers suffering from the burden of the transferring/lifting action, emphasizing the need to introduce a transfer-assistive robot into the care field in South Korea.

Transfer-assistive robots are expected to alleviate the burden of transferring and lifting actions for long-term care workers.These results emphasize the need to introduce transfer-assistive robots in the care field.Ongoing attention to the usability study of transfer-assistive robots may be valuable in improving the work environment of long-term care workers and the quality of care services provided to care receivers.

Modification of SWAT model for simulation of organic matter in Korean watersheds.

The focus of water quality modeling of Korean streams needs to be shifted from dissolved oxygen to algae or organic matter. In particular, the structure of water quality models should be modified to simulate the biochemical oxygen demand (BOD), which is a key factor in calculating total maximum daily loads (TMDLs) in Korea, using 5-day BOD determined in the laboratory (Bottle BOD(5)). Considering the limitations in simulating organic matter under domestic conditions, we attempted to model total organic carbon (TOC) as well as BOD by using a watershed model. For this purpose, the Soil and Water Assessment Tool (SWAT) model was modified and extended to achieve better correspondence between the measured and simulated BOD and TOC concentrations. For simulated BOD in the period 2004-2008, the Nash-Sutcliffe model efficiency coefficient increased from a value of -2.54 to 0.61. Another indicator of organic matter, namely, the simulated TOC concentration showed that the modified SWAT adequately reflected the observed values. The improved model can be used to predict organic matter and hence, may be a potential decision-making tool for TMDLs. However, it needs further testing for longer simulation periods and other catchments.

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.

Comparative evaluation of runoff and water quality using HSPF and SWMM.

Stormwater pollution is the untreated contaminated water that drains into natural waterways from land uses within an urban catchment. Several studies have demonstrated the deterioration of water quality in receiving bodies of water caused by stormwater runoff. The data have reported that urban runoff play primary roles in degrading water quality in adjacent aquatic systems. The accurate estimation of non-pollutant loads from urban runoff and the prediction of water quality in receiving waters are important. The objective of this paper is to assess the applicability of the watershed scale hydrologic and water quality simulation models SWMM and HSPF to simulate the hydrology of a small watershed in the Han River Basin. Monitoring was performed in small scale watersheds, which is homogeneous land use. The applicability of SWMM and HSPF model was examined for small watersheds using hourly monitoring data. The results of SWMM were reasonably reflected with observed data in small scale urban area. HSPF model was effective at specifying parameters related to runoff and water quality when using hourly monitoring data. The watershed models used in this study adequately simulated watershed characteristics and are recommended to support watershed management.

Arabidopsis histidine-containing phosphotransfer factor 4 (AHP4) negatively regulates secondary wall thickening of the anther endothecium during flowering.

Cytokinins are essential hormones in plant development. Arabidopsis histidine-containing phosphotransfer proteins (AHPs) are mediators in a multistep phosphorelay pathway for cytokinin signaling. The exact role of AHP4 has not been elucidated. In this study, we demonstrated young flower-specific expression of AHP4, and compared AHP4-overexpressing (Ox) trangenic Arabidopsis lines and an ahp4 knock-out line. AHP4-Ox plants had reduced fertility due to a lack of secondary cell wall thickening in the anther endothecium and inhibition of IRREGURAR XYLEMs (IRXs) expression in young flowers. Conversely, ahp4 anthers had more lignified anther walls than the wild type, and increased IRXs expression. Our study indicates that AHP4 negatively regulates thickening of the secondary cell wall of the anther endothecium, and provides new insight into the role of cytokinins in formation of secondary cell walls via the action of AHP4.

Purification, crystallization and preliminary X-ray diffraction analysis of a cystathionine beta-synthase domain-containing protein, CDCP2, from Arabidopsis thaliana.

Cystathione beta-synthase domain-containing protein 2 (CDCP2) from Arabidopsis thaliana has been overexpressed and purified to homogeneity. As an initial step towards three-dimensional structure determination, crystals of recombinant CDCP2 protein have been obtained using polyethylene glycol 8000 as a precipitant. The crystals diffracted to 2.4 A resolution using synchrotron radiation and belonged to the trigonal space group P3(1)21 or P3(2)21, with unit-cell parameters a = b = 56.360, c = 82.596 A, alpha = beta = 90, gamma = 120 degrees . The asymmetric unit contains one CDCP2 molecule and the solvent content is approximately 41%.

Estimation of pollutant loads considering dam operation in Han River Basin by BASINS/Hydrological Simulation Program-FORTRAN.

Effective watershed management often demands qualitative and quantitative predictions of the effect of future management activities as arguments for policy makers and administration. The BASINS geographic information system was developed to compute total maximum daily loads, which are helpful to establish hydrological process and water quality modeling system. In this paper the BASINS toolkit HSPF model is applied in 20,271 km(2) large watershed of the Han River Basin is used for applicability of HSPF and BMPs scenarios. For proper evaluation of watershed and stream water quality, comprehensive estimation methods are necessary to assess large amounts of point source and nonpoint-source (NPS) pollution based on the total watershed area. In this study, The Hydrological Simulation Program-FORTRAN (HSPF) was estimated to simulate watershed pollutant loads containing dam operation and applied BMPs scenarios for control NPS pollution. The 8-day monitoring data (about three years) were used in the calibration and verification processes. Model performance was in the range of "very good" and "good" based on percent difference. The water-quality simulation results were encouraging for this large sizable watershed with dam operation practice and mixed land uses; HSPF proved adequate, and its application is recommended to simulate watershed processes and BMPs evaluation.

Identification of genes induced in wound-treated wild rice (Oryza minuta).

A subtracted library was constructed from wound-treated wild rice (Oryza minuta) by suppression subtractive hybridization (SSH) in combination with mirror orientation selection (MOS). To distinguish between differentially expressed transcripts and false positive clones, DNA chips containing 960 random clones were applied as a form of reverse Northern screening. Based on the signal intensities and expression ratios obtained from experiments performed in triplicate, 371 clones were selected. ESTs produced from the subtracted library showed 63.2% redundancy, and 72% of all clones could be matched to the GenBank nonredundant database. Functional categorization placed the identified enriched genes in categories of subcellular localization, metabolism, cell rescue and defense, and transcription. These EST-related resistance mechanisms could be used in investigations into the defense mechanisms of wild species, and to provide new routes to improving the germplasm of cultivated rice.

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.

Estimating the microbial risk of E. coli in reclaimed wastewater irrigation on paddy field.

Microbial risk was quantified to assess human health risk as a result of exposure to E. coli in reclaimed wastewater irrigation. Monitoring data on E. coli were collected from pond water in paddy rice plots during the growing season. Five treatments were used and each was triplicated to evaluate the changes in E. coli concentrations in experiments performed in 2003 and 2004. The Beta-Poisson model was used to estimate the microbial risk of pathogen ingestion among farmers and neighboring children. A Monte Carlo simulation (10,000 trials) was conducted to estimate the risk associated with uncertainty. In this study, risk values ranged from 10(-4) to 10(-8). UV-disinfected irrigation water showed a lower risk value than others, and its level was within the range of the actual paddy rice field with surface water. Agricultural activity was thought to be safer after 1-2 days, when the paddy field was irrigated with reclaimed wastewater. Also, children were found to have a greater risk of infection with E. coli. This paper should be viewed as a first step in the application of quantitative microbial risk assessment of wastewater reuse in paddy rice culture.

Model development for nutrient loading estimates from paddy rice fields in Korea.

A field experiment was performed to evaluate water and nutrient balances in paddy rice culture operations during 2001-2002. The water balance analysis indicated that about half (50-60%) of the total outflow was lost by surface drainage, with the remainder occurring by evapotranspiration (490-530 mm). The surface drainage from paddy fields was mainly caused by rainfall and forced-drainage, and in particular, the runoff during early rice culture periods depends more on the forced-drainage due to fertilization practices. Most of the total phosphorus (T-P) inflow was supplied by fertilization at transplanting, while the total nitrogen (T-N) inflow was supplied by the three fertilizations, precipitation. and from the upper paddy field, which comprised 13-33% of the total inflow. Although most of the nutrient outflow was attributed to plant uptake. nutrient loss by surface drainage was substantial, comprising 20% for T-N and 10% for T-P. Water and nutrient balances indicate that reduction of surface drainage from paddy rice fields is imperative for nonpoint source pollution control. The simplified computer model, PADDIMOD, was developed to simulate water and nutrient (T-N and T-P) behavior in the paddy rice field. The model predicts daily ponded water depth, surface drainage, and nutrient concentrations. It was formulated with a few equations and simplified assumptions, but its application and a model fitness test indicated that the simulation results reasonably matched the observed data. It is a simple and convenient planning model that could be used to evaluate BMPs of paddy rice fields alone or in combination with other complex watershed models. Application of the PADDIMOD to other paddy rice fields with different agricultural environments might require further calibration and validation.

Seasonal performance of constructed wetland and winter storage pond for sewage treatment in Korea.

A pilot study was performed from July 1998 to December 2002 to examine the feasibility of a constructed wetland system for sewage treatment in small communities of Korea. To maintain treatment performance during the winter period, an intermittent-discharge pond was connected to the wetland; its effects were evaluated from December 2001 to April 2003. The subsurface flow (SSF) wetland was satisfactory for treating sewage with good removal efficiency even during the winter period. The wetland effluent concentrations of BOD5 and TSS were often higher in winter than in the growing season, but this was explained by the higher loading rates, rather than lower removal efficiency. The relatively poor-quality wetland effluent was further polished during winter in the pond. The upper layer of the pond water column became remarkably clear immediately after ice melt. Overall, the wetland system was found to be adequate for treating sewage with stable removal efficiency, and the intermittent-discharge pond was found to be effective for further polishing if necessary. Therefore, a wetland and subsequent pond system is recommended as a practical alternative for treating sewage in small communities in Korea, and partial discharge of pond water in March is suggested.