NITRIC OXIDE-ASSOCIATED PROTEIN1 (AtNOA1) is essential for salicylic acid-induced root waving in Arabidopsis thaliana.

Root waving responses have been attributed to both environmental and genetics factors, but the potential inducers and transducers of root waving remain elusive. Thus, the identification of novel signal elements related to root waving is an intriguing field of research. Genetic, physiological, cytological, live cell imaging, and pharmacological approaches provide strong evidence for the involvement of Arabidopsis thaliana NITRIC OXIDE-ASSOCIATED PROTEIN1 (AtNOA1) in salicylic acid (SA)-induced root waving. SA specially induced root waving, with an overall decrease in root elongation in A. thaliana, and this SA-induced response was disrupted in the Atnoa1 mutant, as well as in nonexpresser of pathogenesis-related genes 1 (npr1), which is defective in SA-mediated plant defense signal transduction, but not in npr3/4 single and double mutants. The expression assays revealed that the abundance of AtNOA1 was significantly increased by application of SA. Genetic and pharmacological analyses showed that SA-induced root waving involved an AtNOA1-dependent Ca(2+) signal transduction pathway, and PIN-FORMED2 (PIN2) -based polar auxin transport possibly plays a crucial role in this process. Our work suggests that SA signaling through NPR1 and AtNOA1 is involved in the control of root waving, which provides new insights into the mechanisms that control root growth behavior on a hard agar surface.

A rapid and highly sensitive protocol for the detection of Escherichia coli O157:H7 based on immunochromatography assay combined with the enrichment technique of immunomagnetic nanoparticles.

BACKGROUND: Escherichia coli O157:H7 (E. coli O157:H7) is an important pathogenic bacterium that threatens human health. A rapid, simple, highly sensitive, and specific method for the detection of E. coli O157:H7 is necessary. METHODS: In the present study, immunomagnetic nanoparticles (IMPs) were prepared with nanopure iron as the core, coated with E. coli O157:H7 polyclonal antibodies. These IMPs were used in combination with immunochromatographic assay (ICA) and used to establish highly sensitive and rapid kits (IMPs+ICA) to detect E. coli O157:H7. The kits were then used to detect E. coli O157:H7 in 150 food samples and were compared with conventional ICA to evaluate their efficacy. RESULTS: The average diameter of IMPs was 56 nm and the amount of adsorbed antibodies was 106.0 µg/mg. The sensitivity of ICA and IMPs+ICA was 10(5) colony-forming units/mL and 10(3) CFUs/mL, respectively, for purified E. coli O157:H7 solution. The sensitivity of IMPs+ICA was increased by two orders, and its specificity was similar to ICA. CONCLUSION: The kits have the potential to offer important social and economic benefits in the screening, monitoring, and control of food safety.

Detection of micrometastases in peripheral blood of non-small cell lung cancer with a refined immunomagnetic nanoparticle enrichment assay.

Fe(3)O(4) particles are currently used as the core of immunomagnetic microspheres in the immunomagnetic enrichment assay of circulating tumor cells (CTCs). It is difficult to further improve the sensitivity of CTC detection or to improve tumor cell-type identification and characterization. In the present study, we prepared immunomagnetic nanoparticles with nanopure iron as the core, coated with anti-cytokeratin 7/8 (CK7/8) monoclonal antibody. These immunomagnetic nanoparticles (IMPs) were used in conjunction with immunocytochemistry (ICC) to establish a refined immunomagnetic nanoparticle enrichment assay for CTC detection in non-small cell lung cancer (NSCLC). The assay was compared with nested reverse transcription polymerase chain reaction (RT-PCR) to detect CK19 mRNA and lung specific X protein (LUNX) mRNA. Human lung adenocarcinoma cell line A549 was used for sensitivity and specificity evaluation. Peripheral blood samples were collected from each group for CTC detection. The average diameter of the immunomagnetic nanoparticles was 51 nm, and the amount of adsorbed antibodies was 111.2 µg/mg. We could detect down to one tumor cell in 5 × 10(7) peripheral blood mononuclear cells. The sensitivity was consistent with that of nested RT-PCR; however, the false positive rate was significantly reduced. The modified assay combined with ICC did not differ from nested RT-PCR in sensitivity, but it had significantly increased specificity. This approach could, therefore, contribute to identification of micrometastases, re-defining clinical staging, and guiding individual postoperative treatments. The technique shows considerable potential clinical value and further clinical trials are warranted.

Extracellular Ca²+ alleviates NaCl-induced stomatal opening through a pathway involving H2O2-blocked Na+ influx in Vicia guard cells.

To gain further insights into the function of extracellular Ca²+ in alleviating salt stress, Vicia faba guard cell protoplasts (GCPs) were patch-clamped in a whole-cell configuration. The results showed that 100 mM NaCl clearly induced Na+ influx across the plasma membrane in GCPs and promoted stomatal opening. Extracellular Ca²+ at 10 mM efficiently blocked Na+ influx and inhibited stomatal opening, which was partially abolished by La³+ (an inhibitor of plasma membrane Ca²+ channel) or catalase (CAT, a H2O2 scavenger), respectively. These results suggest that the plasma membrane Ca²+ channels and H2O2 possibly mediate extracellular Ca²+-blocked Na+ influx in GCPs. Furthermore, extracellular Ca²+ activated the plasma membrane Ca²+ channels under NaCl stress, which was partially abolished by CAT. These results, taken together, indicate that hydrogen peroxide (H2O2) likely regulates Na+ uptake by activating plasma membrane Ca²+ channels in GCPs. In accordance with this hypothesis, H2O2 could mimic extracellular Ca²+ to activate Ca²+ channels and block Na+ influx in guard cells. A single-cell analysis of cytosolic free Ca²+ ([Ca²+](cyt)) using Fluo 3-AM revealed that extracellular Ca²+ induced the accumulation of cytosolic Ca²+ under NaCl stress, but had few effects on the accumulation of cytosolic Ca²+ under non-NaCl conditions. All of these results, together with our previous studies showing that extracellular Ca²+ induced the generation of H2O2 in GCPs during NaCl stress, indicate that extracellular Ca²+ alleviates salt stress, likely by activating the H2O2-dependent plasma membrane Ca²+ channels, and the increase in cytosolic Ca²+ appears to block Na+ influx across the plasma membrane in Vicia guard cells, leading to stomatal closure and reduction of water loss.