No abstract

Emerging studies have suggested that there is a close link between inositol phosphate (InsP) metabolism and cellular phosphate (P ) homeostasis in eukaryotes; however, whether a common InsP species is deployed as an evolutionarily conserved metabolic messenger to mediate P signaling remains unknown. Here, using genetics and InsP profiling combined with P -starvation response (PSR) analysis in Arabidopsis thaliana, we showed that the kinase activity of inositol pentakisphosphate 2-kinase (IPK1), an enzyme required for phytate (inositol hexakisphosphate; InsP ) synthesis, is indispensable for maintaining P homeostasis under P -replete conditions, and inositol 1,3,4-trisphosphate 5/6-kinase 1 (ITPK1) plays an equivalent role. Although both ipk1-1 and itpk1 mutants exhibited decreased levels of InsP and diphosphoinositol pentakisphosphate (PP-InsP ; InsP ), disruption of another ITPK family enzyme, ITPK4, which correspondingly caused depletion of InsP and InsP , did not display similar P -related phenotypes, which precludes these InsP species from being effectors. Notably, the level of d/l-Ins(3,4,5,6)P was concurrently elevated in both ipk1-1 and itpk1 mutants, which showed a specific correlation with the misregulated P phenotypes. However, the level of d/l-Ins(3,4,5,6)P is not responsive to P starvation that instead manifests a shoot-specific increase in the InsP level. This study demonstrates a more nuanced picture of the intersection of InsP metabolism and P homeostasis and PSRs than has previously been elaborated, and additionally establishes intermediate steps to phytate biosynthesis in plant vegetative tissues.

No abstract

A novel salicylideneaniline-based fluorescent sensor, SB1, with a unique excited-state intramolecular charge transfer-excited-state intramolecular proton transfer (ESICT-ESIPT) coupled system was synthesized and demonstrated to fluorescently sense CN(-) with specific selectivity and high sensitivity in aqueous media based on ESICT-ESIPT switching. A large blue shift (96 nm) was also observed in the absorption spectra in response to CN(-). The bleaching of the color could be clearly observed by the naked eye. Moreover, SB1-based test strips were easily fabricated and low-cost, and could be used in practical and efficient CN(-) test kits. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations further support the cyanide-induced ESICT-ESIPT switching mechanism. The results provide the proof of concept that the colorimetric and ratiometric fluorescent cyanide-selective chemodosimeter can be created based on an ESICT-ESIPT coupled system.

The surface of a thermoplastic polyurethane (TPU) membrane was treated with low temperature plasma (LTP) and was then grafted with poly(acrylic acid) (PAA), followed by the grafting of water-soluble chitosan (WSC) and heparin (HEP). The surface was characterized with static contact-angle and X-ray photoelectron spectroscopy (XPS). The results showed that the surface densities of peroxides and PAA reached a maximum when treated with LTP for 90 s. A higher pH of the reacting solution led to higher graft densities of WSC and HEP. After WSC and HEP grafting, the hydrophilicity of the TPU membrane was increased. The adsorption of proteins on HEP-grafted TPU membranes was effectively curtailed. In addition, HEP grafting also reduced platelet adhesion, elevated thrombin inactivation, and prolonged the blood coagulation time. According to the L929 fibroblast cell growth inhibition index, the HEP-grafted TPU membranes exhibited non-cytotoxicity. Overall results demonstrated that the HEP immobilization could not only improve the hydrophilicity but also the hemocompatibility of the TPU membrane, while maintaining the ascendant biocompatibility.