1.
Roles of nitric oxide in heavy metal stress in plants: Cross-talk with phytohormones and protein S-nitrosylation.
Wei, L, Zhang, M, Wei, S, Zhang, J, Wang, C, Liao, W
Environmental pollution (Barking, Essex : 1987). 2020;:113943
Abstract
Heavy metal (HM) stress is a major hazard, which significantly affects plant growth and development. In order to confront HM stress, plants directly or indirectly regulate the levels of endogenous nitric oxide (NO), a redox-related signaling molecule involved in wide range of plant growth and development as well as in response to HM stress. In addition, there is now compelling experimental evidence that NO usually mediates signaling processes through interactions with different biomolecules like phytohormones to regulate HM tolerance. Apart from phytohormones, NO partly operates through posttranslational modification of proteins, notably via S-nitrosylation in response to HM stress. Recently, the roles of S-nitrosylation as a regulator of plant responses to HM stress and S-nitrosylated candidates have also been established and detected. Here, we describe the roles of NO in confronting HM phytotoxicity in plants with a particular focus on the presentation and discussion of recent data obtained in this field, which involves in the function of various phytohormones and S-nitrosylation during plant responses to HM stress. Additionally, both importance and challenges of future work are outlined in order to further elucidate the specific mechanisms underlying the roles of NO in plant responses to HM stress.
2.
Single molecule detection of nitric oxide enabled by d(AT)15 DNA adsorbed to near infrared fluorescent single-walled carbon nanotubes.
Zhang, J, Boghossian, AA, Barone, PW, Rwei, A, Kim, JH, Lin, D, Heller, DA, Hilmer, AJ, Nair, N, Reuel, NF, et al
Journal of the American Chemical Society. 2011;(3):567-81
Abstract
We report the selective detection of single nitric oxide (NO) molecules using a specific DNA sequence of d(AT)(15) oligonucleotides, adsorbed to an array of near-infrared fluorescent semiconducting single-walled carbon nanotubes (AT(15)-SWNT). While SWNT suspended with eight other variant DNA sequences show fluorescence quenching or enhancement from analytes such as dopamine, NADH, L-ascorbic acid, and riboflavin, d(AT)(15) imparts SWNT with a distinct selectivity toward NO. In contrast, the electrostatically neutral polyvinyl alcohol enables no response to nitric oxide, but exhibits fluorescent enhancement to other molecules in the tested library. For AT(15)-SWNT, a stepwise fluorescence decrease is observed when the nanotubes are exposed to NO, reporting the dynamics of single-molecule NO adsorption via SWNT exciton quenching. We describe these quenching traces using a birth-and-death Markov model, and the maximum likelihood estimator of adsorption and desorption rates of NO is derived. Applying the method to simulated traces indicates that the resulting error in the estimated rate constants is less than 5% under our experimental conditions, allowing for calibration using a series of NO concentrations. As expected, the adsorption rate is found to be linearly proportional to NO concentration, and the intrinsic single-site NO adsorption rate constant is 0.001 s(-1) μM NO(-1). The ability to detect nitric oxide quantitatively at the single-molecule level may find applications in new cellular assays for the study of nitric oxide carcinogenesis and chemical signaling, as well as medical diagnostics for inflammation.