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Abiotic stress reduces plant growth and crop productivity. However, the mechanism underlying posttranscriptional regulations of stress response remains elusive. Herein, we report the posttranscriptional mechanism of nucleocytoplasmic RNA transport of stress‐responsive transcripts mediated by EgRBP42, a heterogeneous nuclear ribonucleoprotein‐like RNA‐binding protein from oil palm, which could be necessary for rapid protein translation to confer abiotic stress tolerance in plants. Transgenic Arabidopsis overexpressing EgRBP42 showed early flowering through alteration of gene expression of flowering regulators and exhibited tolerance towards heat, cold, drought, flood, and salinity stresses with enhanced poststress recovery response by increasing the expression of its target stress‐responsive genes. EgRBP42 harbours nucleocytoplasmic shuttling activity mediated by the nuclear localization signal and the M9‐like domain of EgRBP42 and interacts directly with regulators in the nucleus, membrane, and the cytoplasm. EgRBP42 regulates the nucleocytoplasmic RNA transport of target stress‐responsive transcripts through direct binding to their AG‐rich motifs. Additionally, EgRBP42 transcript and protein induction by environmental stimuli are regulated at the transcriptional and posttranscriptional levels. Taken together, the posttranscriptional regulation of RNA transport mediated by EgRBP42 may change the stress‐responsive protein profiles under abiotic stress conditions leading to a better adaptation of plants to environmental changes. This study shows that EgRBP42, an RNA‐binding protein from oil palm, is involved in plant response to abiotic stress. Overexpression of EgRBP42 in Arabidopsis conferred drought, flood, salinity, and cold tolerance with early flowering. EgRBP42 harbours nucleocytoplasmic shuttling activity, and it interacts directly and is colocalized with stress‐responsive mRNAs in response to abiotic stresses, suggesting that EgRBP42 may be involved in intracellular transport of stress‐responsive RNAs in response to abiotic stress. [ABSTRACT FROM AUTHOR]

SUMMARY: Sargassum species are one of the major alginate‐producing seaweed species in Asian countries. Alginate is widely used in food, feed, pharmaceutical and medical industries as thickening and stabilizing agents. To establish a set of consistently expressed genes as reference genes for quantitative real‐time polymerase chain reaction (qRT‐PCR) studies of Sargassum polycystum (Fucales, Ochrophyta) in samples collected at two distinct time points from the field, four candidate reference genes, namely ribosomal protein L3 (RPL3), ribosomal protein S15 (RPS15), alpha‐tubulin (α‐TUB) and eukaryotic translation elongation factor 1 alpha (TEF1α), were analyzed using geNorm and NormFinder. The results showed that RPL3, α‐TUB and TEF1α were the most stable genes using both programs, whereas RPS15 gene was shown to be the least stable. Identification of stably expressed reference genes is crucial for qRT‐PCR studies to allow accurate quantification of target gene expression levels. In addition, the expression of key enzyme in the final step of alginate biosynthesis pathway mannuronan C5 epimerase‐SP01411 (MC5E‐SP01411) and mannuronan C5 epimerase‐SP02271 (MC5E‐SP02271) were differentially expressed in the seaweeds collected at two distinct time points from the field. To our knowledge, this is the first report on validation of reference genes for any Sargassum species. Our data provide a basis for the selection of reference genes for future biological research in related studies. [ABSTRACT FROM AUTHOR]

Vitamin C is generally thought to enhance immunity and is widely taken as a supplement especially during cancer treatment. Tamoxifen ( TAM) has both cytostatic and cytotoxic properties for breast cancer. TAM engaged mitochondrial oestrogen receptor beta in MCF-7 cells and induces apoptosis by activation of pro-caspase-8 followed by downstream events, including an increase in reactive oxygen species and the release of pro-apoptotic factors from the mitochondria. In addition to that, TAM binds with high affinity to the microsomal anti-oestrogen-binding site and inhibits cholesterol esterification at therapeutic doses. This study aimed to investigate the role of vitamin C in TAM-mediated apoptosis. Cells were loaded with vitamin C by exposure to dehydroascorbic acid, thereby circumventing in vitro artefacts associated with the poor transport and pro-oxidant effects of ascorbic acid. Pre-treatment with vitamin C caused a dose-dependent attenuation of cytotoxicity, as measured by acridine-orange/propidium iodide ( AO/ PI) and Annexin V assay after treatment with TAM. Vitamin C dose-dependently protected cancer cells against lipid peroxidation caused by TAM treatment. By real-time PCR analysis, an impressive increase in FasL and tumour necrosis factor-α ( TNF-α) m RNA was detected after TAM treatment. In addition, a decrease in mitochondrial transmembrane potential was observed. These results support the hypothesis that vitamin C supplementation during cancer treatment may detrimentally affect therapeutic response. [ABSTRACT FROM AUTHOR]

Galactose-1-phosphate uridylyltransferase (GALT) catalyzes the reversible conversion of glucose-1-phosphate and UDP-galactose to galactose-1-phosphate and UDP-glucose. This enzyme is also responsible for one of the biochemical steps that produce the precursors of agar and agarose. In this study, we report the molecular cloning and sequence analyses of a cDNA encoding GALT, from Gracilaria changii (B. M. Xia et I. A. Abbott) I. A. Abbott, J. Zhang et B. M. Xia, which constitutes a genus of seaweeds that supply more than 60% of the world's agar and agarose. We have subcloned this cDNA into a bacterial expression cloning vector and characterized the enzyme activities of its recombinant proteins in vitro. The GcGALT gene was shown to be up-regulated by salinity stresses. The abundance of transcripts encoding GcGALT was the highest in G. changii, followed by Gracilaria edulis and Gracilaria salicornia in a descending order, corresponding to their respective agar contents. Our findings indicated that GALT could be one of the components that determines the agar yield in Gracilaria species. [ABSTRACT FROM AUTHOR]

SummarySerine biosynthesis in plants proceeds by two pathways; a photorespiratory pathway which is associated with photorespiration and a pathway from phosphoglycerate. A cDNA encoding plastidic phosphoserine aminotransferase (PSAT) which catalyzes the formation of phosphoserine from phosphohydroxypyruvate has been isolated from Arabidopsis thaliana. Genomic DNA blot analysis indicated that this enzyme is most probably encoded by a single gene and is mapped on the lower arm of chromosome 4. The deduced protein contains an N-terminal extension exhibiting the general features of a plastidic transit peptide, which was confirmed by subcellular organelle localization using GFP (green flourescence protein). Northern analysis indicated preferential expression of PSAT in roots of light-grown plants, supporting the idea that the phosphorylated pathway may play an important role in supplying the serine requirement of plants in non-green tissues. In situ hybridization analysis of PSAT revealed that the gene is generally expressed in all types of cells with a significantly higher amount in the meristem tissue of root tips. [ABSTRACT FROM AUTHOR]