Responsible development of nanotechnology calls for improved understanding of how nanomaterial surface energy and reactivity affect potential toxicity. Here, we challenge the paradigm that cytotoxicity increases with nanoparticle reactivity. Higher-surface-energy {001}-faceted CdS nanorods (CdS-H) were less toxic to Saccharomyces cerevisiae than lower-energy ({101}-faceted) nanorods (CdS-L) of similar morphology, aggregate size, and charge. CdS-H adsorbed to the yeast's cell wall to a greater extent than CdS-L, which decreased endocytosis and cytotoxicity. Higher uptake of CdS-L decreased cell viability and increased endoplasmatic reticulum stress despite lower release of toxic Cd(2+) ions. Higher toxicity of CdS-L was confirmed with five different unicellular microorganisms. Overall, higher-energy nanocrystals may exhibit greater propensity to adsorb to or react with biological protective barriers and/or background constituents, which passivates their reactivity and reduces their bioavailability and cytotoxicity.

KEY MESSAGE : Reduced levels of profilin 3 do not have a noticeable phenotypic effect; however, elevated profilin 3 levels result in decreased hypocotyl length due to a reduction in cell elongation and F-actin reorganization. The actin cytoskeleton is critical for a variety of cellular processes. The small actin monomer proteins, profilins (PRFs), are encoded by five highly conserved isoforms in Arabidopsis thaliana. PRF3, one of the vegetative isoforms, has 36 more N-terminal amino acid residues than the other four PRFs; however, the functions of PRF3 are mostly unknown. In this study, we demonstrated that PRF3 was strongly expressed in young seedlings, rosette leaves, and cauline leaves, but was weakly expressed in 14-day-old seedlings and flowers. Our data also showed that PRF3 could increase the critical concentration (Cc) of actin assembly in vitro. Overexpression of the full-length PRF3 cDNA resulted in a decrease in the lengths of roots and hypocotyls and delayed seed germination, but PRF3-ΔN36 transgenic plants and prf3 mutant plants showed normal growth when compared with wild-type plants. Microscopy observation revealed that cell elongation was inhibited in the hypocotyl and that F-actin was reorganized by destabilizing microfilaments. These results suggest that the dwarf phenotype of the PRF3 overexpression seedlings may be related to a reduction in cell length and F-actin rearrangement.

The bamboo shoot of Pleioblastus amarus (Keng) Keng f. is a medicinal and edible plant product in China. In this study, the chemical composition of the total alkaloids from bamboo shoots and bamboo shoot shells of P. amarus (Keng) Keng f. (ABSP and ABSSP, respectively) were separated and investigated by UHPLC/QTOF-MS/MS. The results showed that a total of 32 alkaloids were extracted, with 15 common to both ABSP and ABSSP and 10 and 7 alkaloids distinct to ABSP and ABSSP, respectively. ABSP and ABSSP both decreased the lipopolysaccharide (LPS, 0.5 μg/mL)-induced nitric oxide (NO) production in RAW264.7 murine macrophages with half maximal inhibitory concentration (IC50) values of 78 and 55 μg/mL, respectively. We also found that ABSP and ABSSP (100 μg/mL) could decrease the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at both mRNA and protein levels in LPS-exposed RAW264.7 cells. Moreover, 100 μg/mL of ABSP and ABSSP also significantly inhibited LPS-induced mRNA expression of interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α). Additionally, ABSP and ABSSP (100 μg/mL) decreased the phosphorylation of extracellular regulated protein kinase (ERK) in LPS-stimulated RAW264.7 cells. Collectively, the total alkaloids from the bamboo shoots and shells of P. amarus exhibit anti-inflammatory effects in LPS-activated RAW264.7 cells through the inhibition of ERK signaling. This result can provide support for the medicinal use and further study of P. amarus.