Characterization of Arabidopsis FPS isozymes and FPS gene expression analysis provide insight into the biosynthesis of isoprenoid precursors in seeds

Arabidopsis thaliana contains two genes encoding farnesyl diphosphate (FPP) synthase (FPS), the prenyl diphoshate synthase that catalyzes the synthesis of FPP from isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). In this study, we provide evidence that the two Arabidopsis short FPS isozymes FPS1S and FPS2 localize to the cytosol. Both enzymes were expressed in E. coli, purified and biochemically characterized. Despite FPS1S and FPS2 share more than 90% amino acid sequence identity, FPS2 was found to be more efficient as a catalyst, more sensitive to the inhibitory effect of NaCl, and more resistant to thermal inactivation than FPS1S. Homology modelling for FPS1S and FPS2 and analysis of the amino acid differences between the two enzymes revealed an increase in surface polarity and a greater capacity to form surface salt bridges of FPS2 compared to FPS1S. These factors most likely account for the enhanced thermostability of FPS2. Expression analysis of FPS::GUS genes in seeds showed that FPS1 and FPS2 display complementary patterns of expression particularly at late stages of seed development, which suggests that Arabidopsis seeds have two spatially segregated sources of FPP. Functional complementation studies of the Arabidopsis fps2 knockout mutant seed phenotypes demonstrated that under normal conditions FPS1S and FPS2 are functionally interchangeable. A putative role for FPS2 in maintaining seed germination capacity under adverse environmental conditions is discussed

Electrokinetics and zero valent iron nanoparticles: Experimental and modeling of the transport in different porous media

info:eu-repo/semantics/publishedVersio

Nanoscale zerovalent iron (NZVI) for environmental decontamination:A brief history of 20 years of research and field-scale application

Environmental contamination continues to pose a serious threat to human health and the ecosystem. Over the next several decades, remediation research and business will be actively restoring both legacy and newly spilled sites in many countries worldwide. This chapter critically reviews the 20-year progress (1997–2017) in nanoscale zerovalent iron (NZVI) research and development from laboratory testing to pilot- and field-scale demonstrations. Several major areas of NZVI research, including (1) NZVI synthesis and reactivity, (2) aggregation, (3) transport in porous media, (4) polymer modification including carboxymethyl cellulose (CMC), (5) toxicity, (6) sulfidation, and (7) use of electromagnetic fields to enhance remediation, are discussed. Additionally, we summarize important aspects of pilot- and field-scale NZVI applications from 27 peer-reviewed articles and credible reports including the types of contaminants and NZVI used; delivery techniques; injection concentration, rates, and durations; hydrogeological conditions of the sites; pre-operations (before NZVI application); unexpected phenomena (such as clogging) during or after NZVI application; and performance monitoring including the radius of influence, treatment efficiency, and rebound. Finally, this chapter links the past, present, and future of NZVI research and application to the remaining 15 chapters of this book