Differential down-regulation of zeaxanthin epoxidation in two rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) cultivars with different chilling sensitivities

When the leaf segments of rice (Oryza sativa L.) plants were subjected to chilling in the moderate light, zeaxanthin (Zx) formation was faster in a chilling-tolerant Dongjin-byeo (DJ) than in a chilling-sensitive IR841. Although the rate of Zx formation was accelerated by the treatment of 5 mM salicylaldoxime, an inhibitor of Zx epoxidase (ZE), there was almost no changes in DJ. A similar result was observed when leaf segments were treated with 50 mM sodium fluoride, a potent inhibitor of chloroplast phosphatase. The slow Zx epoxidation in IR841 during light-chilling was confirmed in leaf segments treated with 10 mM dithiothreitol, an inhibitor of violaxanthin de-epoxidase (VDE). However, the differences between the two cultivars were not observed at 25oC. These results suggest that compared with IR841 the higher rate of Zx formation in DJ is not due to the higher VDE activity in DJ but is due to more rapid down-regulation of ZE in DJ, possibly by its phosphorylation. Compared with DJ, IR841 accumulated more superoxide with PSI inactivation during light-chilling, which eliminates the possibility of increased ZE down-regulation in DJ leaves by photo-oxidation. In vitro study with alkaline phosphatase supports the idea of down-regulation of ZE by phosphorylation under light-chilling condition. We propose that this reversible down-regulation of Zx epoxidation possibly by the phosphorylation of ZE is an important regulation mechanism of violaxanthin cycle that confers chilling tolerance of a rice cultivar under chilling stress in the light with moderate intensities.     

高通量测序检测金针菇RNAi转化子插入位点及拷贝数

本研究对金针菇Flammulina velutipes的一个RNAi转化子菌株1382R3进行了高通量测序,以本实验室先前获得的野生型W23基因组数据为参考,分析了该转化子的基因插入位点以及拷贝数。转化子菌株1382R3是通过农杆菌介导将fv-hmg1-RNAi载体转化至金针菇菌株并通过PCR检测筛选标记而得到。通过BLAST将转化子测序的reads对外源载体和基因组定位,找到具有基因组序列（GS）和外源载体序列（ES）两种序列的临界reads,并据此使用PERL语言程序成功在转化子1382R3菌株中找到两个插入位点。对两个插入位置的序列分析表明：在插入位点1,T-DNA片段部分插入;在插入位点2,T-DNA全部插入到基因组。两个插入位点都对基因组内源基因的表达造成了一定的干扰。此方法拓宽了高通量测序技术的应用范围,将其运用到遗传转化插入位置和拷贝数的研究中,有利于食用菌的功能基因组及基因工程研究。     

Recycling wasted biomaterial,crab shells,as an adsorbent for the removal of high concentration of phosphate

In this study, crab shells were recycled as an adsorbent for the removal of phosphate. The effects of shell particle size, temperature, pH and phosphate concentration on phosphate removal were investigated. Shell particles less than 1000 μm in diameter removed more than 85% of 500 mg/L phosphate in 24 h while particles 3350 μm in diameter exhibited only 50% removal efficiency. Temperature showed negligible effect on phosphate removal in the range of 15–45 °C. Although removal efficiency was highest at pH 2.0, the efficiency remained 50–60% at pH of 4.0–10.0. The maximum removal capacity was calculated as 108.9 mg/g through Langmuir isotherm plotting, which was 17.0 and 4.7 times higher than those of coal fly ash and scallop shells, respectively. Although calcium carbonate played an active role in the removal of phosphate, both proteins composing 12.5% of crab shells and cellulose-like backbone of the crab shells also played an important role in phosphate removal.     

Enhanced fungal resistance in Arabidopsis expressing wild rice PR-3 (OgChitIVa) encoding chitinase class IV

Oryza grandiglumis Chitinase IVa (OgChitIVa) cDNA encoding a class IV chitinase was cloned from wild rice (Oryza grandiglumis). OgChitIVa cDNA contains an open reading frame of 867 nucleotides encoding 288 amino acid residues with a predicted molecular weight of 30.4 kDa and isoelectric point of 8.48. Deduced amino acid sequences of OgChitIVa include the signal peptide and chitin-binding domain in the N-terminal domain and conserved catalytic domain. OgChitIVa showed significant similarity at the amino acid level with related monocotyledonous rice and maize chitinase, but low similarity with dicotyledoneous chitinase. Southern blot analysis showed that OgChitIVa genes are present as two copies in the wild rice genome. It was shown that RNA expression of OgChitIVa was induced by defense/stress signaling chemicals, such as jasmonic acid, salicylic acid, and ethephon or cantharidin and endothall or wounding, and yeast extract. It was demonstrated that overexpression of OgChitIVa in Arabidopsis resulted in mild resistance against the fungal pathogen, Botrytis cinerea, by lowering disease rate and necrosis size. RT-PCR analysis showed that PR-1 and PR-2 RNA expression was induced in the transgenic lines. Here, we suggest that a novel OgChitIVa gene may play a role in signal transduction process in defense response against B. cinerea in plants. J.-H. Pak and E.-S. Chung contributed equally to this work.     

Insulin-sensitizing activities of tanshinones,diterpene compounds of the root of Salvia miltiorrhiza Bunge

In this study, the effects of the extract and four tanshinone compounds from the dried root of Salvia miltiorrhiza Bunge (Labiatae) on the tyrosine phosphorylation of the insulin receptor (IR) β-subunit and the downstream signaling were examined in Chinese-hamster ovary cells expressing human insulin receptors (CHO/IR cells) as well as in 3T3-L1 adipocytes. In addition the translocation of the glucose transporter 4 was investigated in 3T3-L1 adipocytes. Total extract of Danshen (1–10 μg/ml) and the four tanshinones (10 μM) did not show any activity, but the total extract and the tanshinone I, IIA and 15, 16-dihydrotanshinone I except cryptotanshinone enhanced the activity of insulin (1 nM) on the tyrosine phosphorylation of the IR as well as the activation of the downstream kinases Akt, ERK1/2, and GSK3β. In the adipocytes the same IR-downstream signaling and the translocation of glucose transporter 4 were demonstrated by the three tanshinones in the presence of insulin. These insulin-sensitizing activities of tanshinones may be useful for developing a new class of specific IR activators as anti-diabetic agents.     

In vitro anti-inflammatory activity of lignans isolated from Magnolia fargesii

The overproduction of nitric oxide (NO) and prostaglandin E₂ (PGE₂) causes neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease. Four lignans, (+)-eudesmin (1), (+)-magnolin (2), (+)-yangambin (3) and a new structure named as epimagnolin B (4) were isolated from Magnolia fargesii (Magnoliaceae) as the inhibitors of NO production in LPS-activated microglia. The most potent compound 4 inhibited the production of NO and PGE₂ and the expression of respective enzyme iNOS and COX-2 through the suppression of I-κB-α degradation and nuclear translocation of p65 subunit of NF-κB.     

Synthesis of phenylisothiourea derivatives as inhibitors of NO production in LPS activated macrophages

A series of phenylisothioureas were synthesized as inhibitors of NO production in lipopolysaccharide-activated macrophages. We investigated the effect of lipophilic moiety and N- or S-substituents of the phenylisothioureas on the activity. Inhibitory activities of carbazole-linked phenylisothioureas were superior to the corresponding simple phenylisothiourea derivatives. Among these compounds, 12b having N-ethyl and S-isopropyl groups on phenylisothiourea moiety was the most potent in the inhibition of NO production. They inhibited NO production through the suppression of the LPS-induced translocation of p65 subunit of NF-κB and the followed suppression of the iNOS protein and mRNA expression.     

Classification of hybrid and altered Vibrio cholerae strains by CTX prophage and RS1 element structure

Analysis of the CTX prophage and RS1 element in hybrid and altered Vibrio cholera O1 strains showed two classifiable groups. Group I strains contain a tandem repeat of classical CTX prophage on the small chromosome. Strains in this group either contain no element(s) or an additional CTX prophage or RS1 element(s) on the large chromosome. Group II strains harbor RS1 and CTX prophage, which has an E1 Tor type rstR and classical ctxB on the large chromosome.     

<Emphasis Type="Italic">Virgibacillus xinjiangensis</Emphasis> sp. nov., isolated from a Salt Lake of Xin-jiang Province in China

A strictly aerobic Gram-positive, moderately halophilic spore forming bacterium, designated strain SL6-1^T, was isolated from a salt lake in Xin-jiang province, China. Growth of strain SL6-1^T was observed at NaCl concentrations of 0∼20% (w/v) (the optimum being 5∼7%, w/v). The peptidoglycan type of strain SL6-1^T was Alγ-meso-diaminopimelic acid and its major cellular fatty acids were iso-C_14:0 and iso-C_16:0 and ante-iso-C_15:0. The major respiratory isoprenoid quinone was MK-7 and the G+C content of the genomic DNA was 44.5 mol%. The major cellular phospholipids were phosphatidylglycerol and diphosphatidylglycerol. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SL6-1^T formed a phylogenetic lineage within the genus Virgibacillus. Based on 16S rRNA gene sequence similarity, the strain was most closely related to Virgibacillus olivae E₃₀8^T, Virgibacillus kekensis YIM kkny16^T, Virgibacillus marismortui DSM 12325^T with 97.1%, 97.1%, and 97.0% gene sequence similarities, respectively and the sequence similarities to other related taxa were less than 96.7%. The DNA relatedness values between strain SL6-1^T and V. olivae E₃₀8^T, V. kekensis YIM kkny16^T, V. marismortui DSM 12325^T were 16.7%, 51.0%, and 22.8%, respectively. On the basis of physiological, biochemical and phylogenetic properties, strain SL6-1^T represents a novel species, for which the name Virgibacillus xinjiangensis sp. nov. is proposed. The type strain is SL6-1^T (=KCTC 13128^T =DSM 19031^T).     

ROS-Mediated ABA Signaling

In plants, reactive oxygen species (ROS) are short-lived molecules produced through various cellular mechanisms in response to biotic and abiotic stimuli. ROS function as second messengers for hormone signaling, development, oxygen deprivation, programmed cell death, and plant–pathogen interactions. Recent research on ROS-mediated responses has produced stimulating findings such as the specific sources of ROS production, molecular elements that work in ROS-mediated signaling and homeostasis, and a ROS-regulated gene network (Neill et al., Curr Opin Plant Biol 5:388–395, 2002a; Apel and Hirt, Annu Rev Plant Biol 55:373–399, 2004; Mittler et al., Trends Plant Sci 9:490–498, 2004; Mori and Schroeder, Plant Physiol 135:702–708, 2004; Kwak et al., Plant Physiol 141:323–329, 2006; Torres et al., Plant Physiol 141:373–378, 2006; Miller et al., Physiol Plant 133:481–489, 2008). In this review, we highlight new discoveries in ROS-mediated abscisic acid (ABA) signaling. Drs. Daeshik Cho and June M. Kwak are the corresponding authors for this paper.