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  1. Abstract

    Nucleic acid biosensing technologies have the capability to provide valuable information in applications ranging from medical diagnostics to environmental sensing. The unique properties of plasmonic metallic nanoparticles have been used for sensing purposes and among them, plasmonic sensors based on surface-enhanced Raman scattering (SERS) offer the advantages of sensitive and muliplexed detection owing to the narrow bandwidth of their characteristic Raman spectral features. This paper describes current applications that employ the unique SERS-based inverse molecular sentinel (iMS) nanobiosensors developed in our laboratory. Herein, we demonstrate the use of label-free iMS nanoprobes for detecting specific nucleic acid biomarkers in a wide variety of applications from cancer diagnostics to genetic monitoring for plant biology in renewable biofuel research.

     
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  2. Summary

    Genetic mutants defective in stimulus‐induced Ca2+increases have been gradually isolated, allowing the identification of cell‐surface sensors/receptors, such as the osmosensor OSCA1. However, determining the Ca2+‐signaling specificity to various stimuli in these mutants remains a challenge. For instance, less is known about the exact selectivity between osmotic and ionic stresses in theosca1mutant.

    Here, we have developed a method to distinguish the osmotic and ionic effects by analyzing Ca2+increases, and demonstrated thatosca1is impaired primarily in Ca2+increases induced by the osmotic but not ionic stress.

    We recorded Ca2+increases induced by sorbitol (osmotic effect, OE) and NaCl/CaCl2(OE + ionic effect, IE) inArabidopsiswild‐type andosca1seedlings. We assumed the NaCl/CaCl2total effect (TE) = OE + IE, then developed procedures for Ca2+imaging, image analysis and mathematic fitting/modeling, and foundosca1defects mainly in OE.

    The osmotic specificity ofosca1suggests that osmotic and ionic perceptions are independent. The precise estimation of these two stress effects is applicable not only to new Ca2+‐signaling mutants with distinct stimulus specificity but also the complex Ca2+signaling crosstalk among multiple concurrent stresses that occur naturally, and will enable us to specifically fine tune multiple signal pathways to improve crop yields.

     
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  3. Plant nucleotide-binding leucine-rich repeat receptors (NLRs) regulate immunity and cell death. InArabidopsis, a subfamily of “helper” NLRs is required by many “sensor” NLRs. Active NRG1.1 oligomerized, was enriched in plasma membrane puncta, and conferred cytoplasmic calcium ion (Ca2+) influx in plant and human cells. NRG1.1-dependent Ca2+influx and cell death were sensitive to Ca2+channel blockers and were suppressed by mutations affecting oligomerization or plasma membrane enrichment. Ca2+influx and cell death mediated by NRG1.1 and ACTIVATED DISEASE RESISTANCE 1 (ADR1), another helper NLR, required conserved negatively charged N-terminal residues. Whole-cell voltage-clamp recordings demonstrated thatArabidopsishelper NLRs form Ca2+-permeable cation channels to directly regulate cytoplasmic Ca2+levels and consequent cell death. Thus, helper NLRs transduce cell death signals directly.

     
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