TsHKT1;2, a HKT1 homolog from the extremophile arabidopsis relative Thellungiella salsuginea, shows K \u3csup\u3e+\u3c/sup\u3e specificity in the presence of NaCl

Cellular Na +/K + ratio is a crucial parameter determining plant salinity stress resistance. We tested the function of plasma membrane Na +/K + cotransporters in the High-affinity K + Transporter (HKT) family from the halophytic Arabidopsis (Arabidopsis thaliana) relative Thellungiella salsuginea. T. salsuginea contains at least two HKT genes. TsHKT1;1 is expressed at very low levels, while the abundant TsHKT1;2 is transcriptionally strongly up-regulated by salt stress. TsHKT-based RNA interference in T. salsuginea resulted in Na + sensitivity and K + deficiency. The athkt1 mutant lines overexpressing TsHKT1;2 proved less sensitive to Na + and showed less K + deficiency than lines overexpressing AtHKT1. TsHKT1;2 ectopically expressed in yeast mutants lacking Na + or K + transporters revealed strong K + transporter activity and selectivity for K + over Na +. Altering two amino acid residues in TsHKT1;2 to mimic the AtHKT1 sequence resulted in enhanced sodium uptake and loss of the TsHKT1;2 intrinsic K + transporter activity. We consider the maintenance of K + uptake through TsHKT1;2 under salt stress an important component supporting the halophytic lifestyle of T. salsuginea. © 2012 American Society of Plant Biologists

Establishment and Application of a Monitoring Strategy for Living Modified Cotton in Natural Environments in South Korea

Cotton (Gossypium hirsutum L.) is grown worldwide for its natural hollow fibers and is used as cattle feed. Living modified (LM) cotton is not cultivated in South Korea and must be imported for food, feed, and processing. From 2009 to 2013, the Ministry of Environment (MOE) and the National Institute of Ecology (NIE) conducted a natural environment monitoring and post-management initiative for living modified organisms (LMOs) in some areas to reduce the likelihood of harmful effects caused by unintentionally discharged LMOs during transportation and use. In this study, we adopted a new strategy to identify unintentionally released LM cotton plants nationwide from 2014 to 2018. A total of 451 suspicious cotton samples were collected from 3921 survey sites. Among them, we identified 255 LM cotton plants, of which approximately 72.2% had transgenic herbicide and insecticide traits. The majority of the samples were collected from the roadside along transportation routes and from stockbreeding farms. This study establishes an LMO safety management system to efficiently maintain conservation efforts in South Korea. Our findings suggest that these efforts may play a key role in safely transporting, using, and managing approved LMOs, as well as in regulating unintentionally released LMOs, in order to preserve the natural ecosystem of South Korea

Effectiveness of a Priority Management Scheme of Living Modified Organism Re-Collection Areas in Natural Environments of South Korea

Since 2009, the Ministry of Environment and the National Institute of Ecology in South Korea have been conducting a living modified organism (LMO) monitoring and post-management project in natural environments to prevent the unintentional release and spread of LMOs to natural ecosystems. The project surveyed six administrative districts of South Korea from 2009 to 2013 and collected 1960 LMO suspicious samples from 1850 monitoring sites. As a result, 113 LMOs were identified at 65 sites and removed for post-management. An analysis of the five-year LMO monitoring results showed that LMOs were re-collected in 38.4% of the 65 areas where they were initially collected. This result led to the establishment of a new LMO management system in 2014, with priority given to areas where LMOs had been re-collected twice or more within the last five years. Intensive surveys and post-management were conducted four times a year in these priority management areas. The results confirmed that the novel management system for LMO priority areas effectively prevented the continuous collection of LMOs in the same areas. In conclusion, establishing a safety management system for priority management areas, intensive surveys, and post-management efforts are crucial for protecting natural ecosystems from the putative risks of unintentionally released LMOs

Functional Mechanisms Underlying the Antimicrobial Activity of the <i>Oryza sativa</i> Trx-like Protein

Plants are constantly subjected to a variety of environmental stresses and have evolved regulatory responses to overcome unfavorable conditions that might reduce or adversely change a plant&#8217;s growth or development. Among these, the regulated production of reactive oxygen species (ROS) as a signaling molecule occurs during plant development and pathogen defense. This study demonstrates the possible antifungal activity of Oryza sativa Tetratricopeptide Domain-containing thioredoxin (OsTDX) protein against various fungal pathogens. The transcription of OsTDX was induced by various environmental stresses known to elicit the generation of ROS in plant cells. OsTDX protein showed potent antifungal activity, with minimum inhibitory concentrations (MICs) against yeast and filamentous fungi ranging between 1.56 and 6.25 and 50 and 100 &#181;g/mL, respectively. The uptake of SYTOX-Green into fungal cells and efflux of calcein from artificial fungus-like liposomes suggest that its killing mechanism involves membrane permeabilization and damage. In addition, irregular blebs and holes apparent on the surfaces of OsTDX-treated fungal cells indicate the membranolytic action of this protein. Our results suggest that the OsTDX protein represents a potentially useful lead for the development of pathogen-resistant plants

Quantitative Analysis of Sphingomyelin by High-Performance Liquid Chromatography after Enzymatic Hydrolysis

Sphingomyelin is the most abundant sphingolipid in mammalian cells and is mostly present in the plasma membrane. A new analytical method using high-performance liquid chromatography (HPLC) was developed to quantify sphingomyelin in mouse plasma and tissues, 3T3-L1 cells, rat aortic smooth muscle cells, and HT-29 cells. Sphingomyelin and dihydrosphingomyelin, an internal standard, were separated by high-performance thin-layer chromatography and simultaneously hydrolyzed with sphingolipid ceramide N-deacylase and sphingomyelinase to release sphingosine and dihydrosphingosine, respectively. Sphingomyelin content was measured by HPLC following o-phthalaldehyde derivatization. Sphingomyelin concentrations in 3T3-L1 cells, rat aortic smooth muscle cells, and HT-29 cells were 60.10±0.24, 62.69±0.08, and 58.38±0.37 pmol/μg protein, respectively, whereas those in brain, kidney, and liver of ICR mice were 55.60±0.43, 43.75±0.21, and 22.26±0.14 pmol/μg protein. The sphingomyelin concentration in mouse plasma was 407.40±0.31 μM. The limits of detection and quantification for sphingomyelin were 5 and 20 pmol, respectively, in the HPLC analysis with fluorescence detection. This sensitivity was sufficient for analyzing sphingomyelin in biological samples. In conclusion, this analytical method is a sensitive and specific technique for quantifying sphingomyelin and was successfully applied to diverse biological samples with excellent reproducibility