Calluses from two ecotypes of reed (Phragmites communis Trin.) plant (dune reed [DR] and swamp reed [SR]), which show different sensitivity to salinity, were used to study plant adaptations to salt stress. Under 200 mm NaCl treatment, the sodium (Na) percentage decreased, but the calcium percentage and the potassium (K) to Na ratio increased in the DR callus, whereas an opposite changing pattern was observed in the SR callus. Application of sodium nitroprusside (SNP), as a nitric oxide (NO) donor, revealed that NO affected element ratios in both DR and SR calluses in a concentration-dependent manner. N -nitro-l-arginine (an NO synthase inhibitor) and 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxyde (a specific NO scavenger) counteracted NO effect by increasing the Na percentage, decreasing the calcium percentage and the K to Na ratio. The increased activity of plasma membrane (PM) H ϩ -ATPase caused by NaCl treatment in the DR callus was reversed by treatment with N -nitro-l-arginine and 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxyde. Western-blot analysis demonstrated that NO stimulated the expression of PM H ϩ -ATPase in both DR and SR calluses. These results indicate that NO serves as a signal in inducing salt resistance by increasing the K to Na ratio, which is dependent on the increased PM H ϩ -ATPase activity.When plants are exposed to NaCl, cellular ion homeostasis may be impaired. Under salinity conditions, tolerant plants typically maintain high potassium (K ϩ ) and low sodium (Na ϩ ) in the cytosol of cells (Greenway and Munns, 1980; Jeschke, 1984). Such mechanisms involve Na ϩ compartmentalization into vacuoles and/or extrusion to the external medium and K ϩ accumulation in the cytoplasm. These processes appear to be mediated by several transport systems, such as H ϩ -ATPase, carriers (symporters and antiporters), and channels associated with plasma membranes (PMs) and tonoplasts (Niu et al., 1995; Rausch et al., 1996).Control of Na ϩ movement across the PM and tonoplast to maintain a low Na ϩ concentration in the cytoplasm is a key factor of cellular adaptation to salt stress (Niu et al., 1995; Rausch et al., 1996). Na ϩ transport across the PM is dependent on the electrochemical gradient created by the PM H ϩ -ATPase (Serrano, 1996). PM H ϩ -ATPase belongs to a family of P-type ATPase, which has a catalytic subunit of approximately 100 kD. This enzyme is a proton pump, whose major role couples ATP hydrolysis to proton transport and creates electrochemical gradient across the PM used by secondary transporters (Serrano, 1989). In addition, this membrane protein is involved in many physiological processes, including salt tolerance, intracellular pH regulation, stomatal opening, and cell elongation (Rayle and Cleland, 1992;Niu et al., 1993; Michelet and Boutry, 1995; Cosgrove, 1997; Kerkeb et al., 2001; Yang et al., 2003). The PM H ϩ -ATPase is encoded by a multigene family, and at least 10 isoforms of the H ϩ -ATPase exist in plants. Krysan et al. (1996) analyzed T-DNA knockout Arab...

We previously reported that nitric oxide (NO) functions as a signal in thermotolerance. To illustrate its relationship with hydrogen peroxide (H 2 O 2 ) in the tolerance of Arabidopsis (Arabidopsis thaliana) to heat shock (HS), we investigated the effects of heat on Arabidopsis seedlings of the following types: the wild type; three NADPH oxidase-defective mutants that exhibit reduced endogenous H 2 O 2 levels (atrbohB, atrbohD, and atrbohB/D); and a mutant that is resistant to inhibition by fosmidomycin (noa1, for nitric oxide-associated protein1). After HS, the NO levels in atrbohB, atrbohD, and atrbohB/D seedlings were lower than that in wildtype seedlings. Treatment of the seedlings with sodium nitroprusside or S-nitroso-N-acetylpenicillamine partially rescued their heat sensitivity, suggesting that NO is involved in H 2 O 2 signaling as a downstream factor. This point was verified by phenotypic analyses and thermotolerance testing of transgenic seedlings that overexpressed Nitrate reductase2 and NOA1, respectively, in an atrbohB/D background. Electrophoretic mobility shift assays, western blotting, and real-time reverse transcription-polymerase chain reaction demonstrated that NO stimulated the DNA-binding activity of HS factors and the accumulation of HS proteins through H 2 O 2 . These data indicate that H 2 O 2 acts upstream of NO in thermotolerance, which requires increased HS factor DNA-binding activity and HS protein accumulation.

Mutagenesis screening is a powerful forward genetic approach that has been successfully applied in lower-model organisms to discover genetic factors for biological processes. This phenotype-based approach has yet to be established in vertebrates for probing major human diseases, largely because of the complexity of colony management. Herein, we report a rapid strategy for identifying genetic modifiers of cardiomyopathy (CM). Based on the application of doxorubicin stress to zebrafish insertional cardiac (ZIC) mutants, we identified 4 candidate CM-modifying genes, of which 3 have been linked previously to CM. The long isoform of DnaJ (Hsp40) homolog, subfamily B, member 6b (dnajb6b(L)) was identified as a CM susceptibility gene, supported by identification of rare variants in its human ortholog DNAJB6 from CM patients. Mechanistic studies indicated that the deleterious, loss-of-function modifying effects of dnajb6b(L) can be ameliorated by inhibition of ER stress. In contrast, overexpression of dnajb6(L) exerts cardioprotective effects on both fish and mouse CM models. Together, our findings establish a mutagenesis screening strategy that is scalable for systematic identification of genetic modifiers of CM, feasible to suggest therapeutic targets, and expandable to other major human diseases.

To characterize the role of nitric oxide (NO) in the tolerance of Arabidopsis (Arabidopsis thaliana) to heat shock (HS), we investigated the effects of heat on three types of Arabidopsis seedlings: wild type, noa1(rif1) (for nitric oxide associated1/resistant to inhibition by fosmidomycin1) and nia1nia2 (for nitrate reductase [NR]-defective double mutant), which both exhibit reduced endogenous NO levels, and a rescued line of noa1(rif1). After HS treatment, the survival ratios of the mutant seedlings were lower than those of wild type; however, they were partially restored in the rescued line. Treatment of the seedlings with sodium nitroprusside or S-nitroso-N-acetylpenicillamine revealed that internal NO affects heat sensitivity in a concentrationdependent manner. Calmodulin 3 (CaM3) is a key component of HS signaling in Arabidopsis. Real-time reverse transcriptionpolymerase chain reaction analysis after HS treatment revealed that the AtCaM3 mRNA level was regulated by the internal NO level. Sodium nitroprusside enhanced the survival of the wild-type and noa1(rif1) seedlings; however, no obvious effects were observed for cam3 single or cam3noa1(rif1) double mutant seedlings, suggesting that AtCaM3 is involved in NO signal transduction as a downstream factor. This point was verified by phenotypic analysis and thermotolerance testing using seedlings of three AtCaM3-overexpressing transgenic lines in an noa1(rif1) background. Electrophoretic mobility-shift and western-blot analyses demonstrated that after HS treatment, NO stimulated the DNA-binding activity of HS transcription factors and the accumulation of heat shock protein 18.2 (HSP18.2) through AtCaM3. These data indicate that NO functions in signaling and acts upstream of AtCaM3 in thermotolerance, which is dependent on increased HS transcription factor DNAbinding activity and HSP accumulation.

Histone H3K4 demethylase LSD1 plays an important role in stem cell biology, especially in the maintenance of the silencing of differentiation genes. However, how the function of LSD1 is regulated and the differentiation genes are derepressed are not understood. Here, we report that elimination of LSD1 promotes embryonic stem cell (ESC) differentiation toward neural lineage. We showed that the destabilization of LSD1 occurs posttranscriptionally via the ubiquitin-proteasome pathway by an E3 ubiquitin ligase, Jade-2. We demonstrated that Jade-2 is a major LSD1 negative regulator during neurogenesis in vitro and in vivo in both mouse developing cerebral cortices and zebra fish embryos. Apparently, Jade-2-mediated degradation of LSD1 acts as an antibraking system and serves as a quick adaptive mechanism for re-establishing epigenetic landscape without more laborious transcriptional regulations. As a potential anticancer strategy, Jade-2-mediated LSD1 degradation could potentially be used in neuroblastoma cells to induce differentiation toward postmitotic neurons.

Cucumber is vulnerable to many foliage diseases. Recent studies reported cloning of candidate genes for several diseases in cucumber; however, the exact defence mechanisms remain unclear. Dof genes have been shown to play significant roles in plant growth, development, and responses to biotic and abiotic stresses. Dof genes coding for plant-specific transcription factors can promote large-scale expression of defence-related genes at whole genome level. The genes in the family have been identified and characterized in several plant species, but not in cucumber. In the present study, we identified 36 CsDof members from the cucumber draft genomes which could be classified into eight groups. The proportions of the CsDof family genes, duplication events, chromosomal locations, cis-elements and miRNA target sites were comprehensively investigated. Consequently, we analysed the expression patterns of CsDof genes in specific tissues and their response to two biotic stresses (watermelon mosaic virus and downy mildew). These results indicated that CsDof may be involved in resistance to biotic stresses in cucumber.

The S100 gene family is closely associated with ESCC.

No abstract