Titanium dioxide nanoparticles oral exposure induce osteoblast apoptosis, inhibit osteogenic ability and increase lipogenesis in mouse.

Titanium dioxide nanoparticles (TiO2-NPs) are widely used in food, paint, coating, cosmetic, and composite orthodontic material. As a common food additive, TiO2-NPs can accumulate in various organs of human body, but the effect and underlying mechanism of bone remain unclear. Here mice were exposed to TiO2-NPs by oral gavage, and histological staining of femoral sections showed that TiO2-NPs reduced bone formation and enhanced osteoclast activity and lipogenesis, contributing to decreased trabecula bone. Transmission electron microscope (TEM) as well as biochemical and flow cytometry analysis of osteoblast exhibited that TiO2-NPs accumulated in osteoblast cytoplasm and impaired mitochondria ultrastructure with increased reactive oxygen species (ROS) and lipid hyperoxide, resulting in osteoblast apoptosis. In terms of mechanism, TiO2-NPs treatment inhibited expression of AKT and then increased pro-apoptotic protein Bax expression which was failure to form heterodimers with decreased anti-apoptotic Bcl-2, activating downstream Caspase-9 and Caspase-3 and inducing apoptosis. Additionally, TiO2-NPs suppressed Wnt3a level and then activated anti-Glycogen synthesis kinase (GSK-3ß) phosphorylation, and ultimately resulted in degradation of ß-catenin which down-regulated Runt-related transcription factor 2 (Runx2) and Osterix, inhibiting expression of osteogenic related proteins. Together, these results revealed that exposure of TiO2-NPs induced apoptosis and inhibited osteoblast differentiation through suppressing PI3K/AKT and Wnt/ß-catenin signaling pathways, resulting in reduction of trabecula bone.

Encoded sewing soft textile robots.

Incorporating soft actuation with soft yet durable textiles could effectively endow the latter with active and flexible shape morphing and motion like mollusks and plants. However, creating highly programmable and customizable soft robots based on textiles faces a longstanding design and manufacturing challenge. Here, we report a methodology of encoded sewing constraints for efficiently constructing three-dimensional (3D) soft textile robots through a simple 2D sewing process. By encoding heterogeneous stretching properties into three spatial seams of the sewed 3D textile shells, nonlinear inflation of the inner bladder can be guided to follow the predefined spatial shape and actuation sequence, for example, tendril-like shape morphing, tentacle-like sequential manipulation, and bioinspired locomotion only controlled by single pressure source. Such flexible, efficient, scalable, and low-cost design and formation methodology will accelerate the development and iteration of soft robots and also open up more opportunities for safe human-robot interactions, tailored wearable devices, and health care.

Dynamically Rotating Magnetic Levitation to Characterize the Spatial Density Heterogeneity of Materials.

Magnetic levitation (MagLev) is a promising technology for density-based analysis and manipulation of nonmagnetic materials. One major limitation is that extant MagLev methods are based on the static balance of gravitational-magnetic forces, thereby leading to an inability to resolve interior differences in density. Here a new strategy called "dynamically rotating MagLev" is proposed, which combines centrifugal force and nonlinear magnetic force to amplify the interior differences in density. The design of the nonlinear magnetic force in tandem with centrifugal force supports the regulation of stable equilibriums, enabling different homogeneous objects to reach distinguishable equilibrium orientations. Without reducing the magnetic susceptibility, the dynamically rotating MagLev system can lead to a relatively large change in orientation angle (∆ψ > 50°) for the heterogeneous parts with small inclusions (volume fraction VF = 2.08%). The rich equilibrium states of levitating objects invoke the concept of levitation stability, which is employed, for the first time, to characterize the spatial density heterogeneity of objects. Exploiting the tunable nonlinear levitation behaviors of objects provides a new paradigm for developing operationally simple, nondestructive density heterogeneity characterization methods. Such methods have tremendous potential in applications related to sorting, orienting, and assembling objects in three dimensions.

Simultaneous detection of plant growth regulators jasmonic acid and methyl jasmonate in plant samples by a monoclonal antibody-based ELISA.

Methyl jasmonate (MeJA) and its free-acid form, jasmonic acid (JA), collectively referred to as jasmonates (JAs), are natural plant growth regulators that are widely present in higher plants. Simultaneous detection of JA and MeJA in plant samples is of significance and is a great challenging issue. In this study, coupling with two extraction methods, a sensitive monoclonal antibody (mAb) based enzyme-linked immunosorbent assay (ELISA) for simultaneous detection of JA and MeJA in plant samples was developed. The JA-bovine serum albumin (BSA) conjugate was used as an immunogen for the production of mAb. As the produced mAb exhibited higher recognition ability towards MeJA than towards JA, ELISA was established using MeJA as the standard. Under optimal experimental conditions, the IC50 and LOD values of ELISA for MeJA were 2.02 ng mL-1 and 0.20 ng mL-1, respectively. In the first extraction method, MeJA in plant samples was evaporated and only JA was extracted. In the second extraction method, both JA and MeJA were extracted. After methylation, JA in the extracts was converted into MeJA, and the whole MeJA in the extracts was measured by ELISA. Plant samples including the leaves of Salvia splendens, the flowers of Salvia splendens and the fruit of grapes were collected. JA and MeJA in these samples were detected by the proposed ELISA. It was found that the concentrations of JA in these three plant samples were about 3-5 times higher than those of MeJA in those samples. ELISA was also confirmed by HPLC. There was a good correlation between ELISA and HPLC.

Changes in glutathione redox cycle during diapause determination and termination in the bivoltine silkworm, Bombyx mori.

To explore whether glutathione regulates diapause determination and termination in the bivoltine silkworm Bombyx mori, we monitored the changes in glutathione redox cycle in the ovary of both diapause- and nondiapause-egg producers, as well as those in diapause eggs incubated at different temperatures. The activity of thioredoxin reductase (TrxR) was detected in ovaries but not in eggs, while neither ovaries nor eggs showed activity of glutathione peroxidase. A lower reduced glutathione/oxidized glutathione (GSH/GSSG) ratio was observed in the ovary of diapause-egg producers, due to weaker reduction of oxidized glutathione (GSSG) to the reduced glutathione (GSH) catalyzed by glutathione reductase (GR) and TrxR. This indicates an oxidative shift in the glutathione redox cycle during diapause determination. Compared with the 25°C-treated diapause eggs, the 5°C-treated diapause eggs showed lower GSH/GSSG ratio, a result of stronger oxidation of GSH catalyzed by thioredoxin peroxidase and weaker reduction of GSSG catalyzed by GR. Our study demonstrated the important regulatory role of glutathione in diapause determination and termination of the bivoltine silkworm.

Variations of hydrogen peroxide and catalase expression in Bombyx eggs during diapause initiation and termination.

For diapause eggs of the silkworm, Bombyx mori, diapause initiation is prevented with hydrochloric acid (HCl) at around 20 h post-oviposition while diapause status is terminated with chilling around 5°C. To investigate whether hydrogen peroxide (H(2)O(2)) and catalase expression are involved in diapause initiation and termination, the concentration of H(2)O(2), relatively higher levels of catalase mRNA and activity of catalase were compared between (1) 20-h-old diapause eggs and the HCl-treated diapause eggs, and (2) 10-day-old diapause eggs and the 5°C-chilled diapause eggs. Compared to diapause eggs, the HCl-treated eggs had significantly higher H(2)O(2) concentrations (up from approximately 1-3 µmol/g fresh mass to 5-8 µmol/g fresh mass), higher relative level of catalase mRNA (up from 0 to 35.2%) and higher catalase activity (up from 2.51 units/mg protein to 4.97 units/mg protein) at 96 h post-treatment. On the other hand, the 5°C chilling resulted in significant increases of H(2)O(2) concentration (up from 0.79 µmol/g fresh mass to 5.57 µmol/g fresh mass), relative level of catalase mRNA (up from 0 to 71.4%) and catalase activity (up from 0.88 units/mg protein to 3.42 units/mg protein) within 120 days. The results obtained in this work suggest that variations of H(2)O(2) and catalase expression in Bombyx eggs are involved in diapause initiation and termination.

Metabolism of hydrogen peroxide in univoltine and polyvoltine strains of silkworm (Bombyx mori).

Recent work has demonstrated that hydrogen peroxide functions as a signaling molecule controlling different essential processes in plants and mammals, which can be produced by superoxide dismutase (SOD) and xanthine oxidase (XO) and decomposed by catalase (CAT), respectively. Progeny diapause of the silkworm, Bombyx mori, is induced by diapause hormone (DH) and the expression of DH gene in the maternal generation has been determined. In order to investigate the relationship between the metabolism of H(2)O(2) and the expression of DH gene, level of H(2)O(2) and activities of SOD, XO and CAT between univoltine and polyvoltine strains, which can produce diapause and non-diapause eggs, respectively, at embryonic and pupal stages were measured. Our results showed that there were significant differences in the metabolism of hydrogen peroxide between two strains and between embryonic and pupal stages. Compared to polyvoltine strain, level of hydrogen peroxide in univoltine strain was significantly higher from stage 19 to stage 21 but lower from stage 24 to stage 29 and the whole pupal stage (Fig. 1). Variations of hydrogen peroxide indicated that hydrogen peroxide may be involved in the active release of DH and the progeny diapause decision by DH rather than the expression of DH gene.