Endocytosis-Mediated Transport of Pb in Rat Blood Cells.

Blood is an important reservoir for Pb storage in living organisms, and the storage of Pb in blood cells inhibits its discharge from blood. However, the mechanism and molecular targets of Pb entry and exit from blood cells have not been elucidated, which is the major barrier to reducing blood Pb levels in normal human beings. In this study, we explored the effect of Pb-binding proteins on blood Pb levels in rats at environmentally relevant concentrations (0.32 µg/g) by identifying the functions of Pb-binding proteins and validating them with inhibitors. The results showed that Pb-binding proteins in blood cells were mainly related to phagocytosis, while in plasma, they were mainly involved in the regulation of endopeptidase activity. Meanwhile, at the normal population Pb levels, endocytosis inhibitors, endopeptidase activity inhibitors, and coadministration of both can reduce the level of Pb in MEL (mouse erythroleukemia cells) cells by up to 50, 40, and 50%, respectively, while in rat blood, the reduction can reach up to 26, 13, and 32%, respectively. Collectively, these findings reveal that endocytosis increases blood Pb levels and provides a possible molecular target for Pb excretion at ambient concentrations.

Transformation of Mercuric Ions to Mercury Nanoparticles in Diatom Chaetoceros curvisetus.

Particulate HgS play crucial roles in the mercury (Hg) cycle. Approximately 20-90% of dissolved Hg can be transformed into particulate HgS by algae. However, detailed knowledge regarding these particles, including sizes and distribution, remains unknown. The present study explored the formation, distribution, and excretion of mercury nanoparticles (HgNPs) in diatom Chaetoceros curvisetus. The results demonstrated that HgNPs (HgS nanoparticles, 29.6-66.2 nm) formed intracellularly upon exposure to 5.0-100.0 µg L-1 Hg(II), accounting for 12-27% of the total Hg. HgNP concentrations significantly increased with increasing intracellular Hg(II) concentrations, while their sizes remained unaffected. HgNPs formed intracellularly and partly accumulated inside the cells (7-11%). Subsequently, the sizes of intracellular HgNPs gradually decreased to facilitate expulsion, 21-50% of which were excreted. These suggested the vital roles of HgNPs in comprehending marine Hg fate. Their unique physicochemical properties and bioavailability would influence Hg biotransformation in the ocean. Additionally, both intracellular and extracellular HgNPs contributed to Hg settling with cells, ultimately leading to Hg burial in sediments. Overall, these findings further deepened our understanding of Hg biotransformation and posed challenges in accurately estimating marine Hg flux and Hg burial.

Rice Seedlings and Microorganisms Mediate Biotransformation of Se in CdSe/ZnS Quantum Dots to Volatile Alkyl Selenides.

Quantum dots (QDs) are widely applied and inevitably released into the environment. The biotransformation of Se in typical CdSe/ZnS QDs coated with glutathione (CdSe/ZnS-GSH) to volatile alkyl selenides and the fate of alkyl selenides in the hydroponically grown rice system were investigated herein. After a 10-day exposure to CdSe/ZnS-GSH (100 nmol L-1), seven alkyl selenides, dimethyl selenide (DMSe), dimethyl diselenide (DMDSe), methyl selenol (MSeH), ethylmethyl selenide (EMSe), ethylmethyl diselenide (EMDSe), dimethyl selenenyl sulfide (DMSeS), and ethylmethyl selenenyl sulfide (EMSeS), were detected in the exposure system using the suspect screening strategy. CdSe/ZnS-GSH was first biotransformed to DMSe and DMDSe by plant and microorganisms. The generated DMSe was volatilized to the gas phase, adsorbed and absorbed by leaves and stems, downward transported, and released into the hydroponic solution, whereas DMDSe tended to be adsorbed/absorbed by roots and upward transported to stems. The airborne DMSe and DMDSe also partitioned from the gas phase to the hydroponic solution. DMSe and DMDSe in the exposure system were further transformed to DMSeS, EMSeS, EMSe, EMDSe, and MSeH. This study gives a comprehensive understanding on the behaviors of Se in CdSe/ZnS-GSH in a rice plant system and provides new insights into the environmental fate of CdSe/ZnS QDs.

The Availability of Space Service for Inter-Satellite Links in Navigation Constellations.

Global navigation satellite systems (GNSS) are widely used in low Earth orbit (LEO) satellite navigation; however, their availability is poor for users in medium Earth orbits (MEO), and high Earth orbits (HEO). With the increasing demand for navigation from MEO and HEO users, the inadequate coverage of GNSS has emerged. Inter-satellite links (ISLs) are used for ranging and communication between navigation satellites and can also serve space users that are outside the navigation constellation. This paper aims to summarize their application method and analyze their service performance. The mathematical model of visibility is proposed and then the availability of time division ISLs is analyzed based on global grid points. The BeiDou navigation constellation is used as an example for numerical simulation. Simulation results show that the availability can be enhanced by scheduling more satellites and larger beams, while the presence of more users lowers the availability. The availability of navigation signals will be strengthened when combined with the signals from the ISLs. ISLs can improve the space service volume (SSV) of navigation constellations, and are therefore a promising method for navigation in MEO/HEO spacecraft.

Rapid determination of toxic and essential metal binding proteins in biological samples by size exclusion chromatography-inductively coupled plasma tandem mass spectrometry.

Metalloproteins binding with trace elements play a crucial role in biological processes and on the contrary, those binding with exogenous heavy metals have adverse effects. However, the methods for rapid, high sensitivity and simultaneous analysis of these metalloproteins are still lacking. In this study, a fast method for simultaneously determination of both essential and toxic metal-containing proteins was developed by coupling size exclusion chromatography (SEC) with inductively coupled plasma tandem mass spectrometry (ICP-MS/MS). After optimization of the separation and detection conditions, seven metalloproteins with different molecular weight (from 16.0 to 443.0 kDa) were successfully separated within 10 min and the proteins containing iron (Fe), copper (Cu), zinc (Zn), iodine (I) and lead (Pb) elements could be simultaneously detected with the use of oxygen as the collision gas in ICP-MS/MS. Accordingly, the linear relationship between log molecular weight and retention time was established to estimate the molecular weight of unknown proteins. Thus, the trace metal and toxic metal containing proteins could be detected in a single run with high sensitivity (detection limits in the range of 0.0020-2.5 µg/mL) and good repeatability (relative standard deviations lower than 4.5 %). This method was then successfully used to analyze metal (e.g., Pb, Zn, Cu and Fe) binding proteins in the blood of Pb-intoxicated patients, and the results showed a negative correlation between the contents of zinc and lead binding proteins, which was identified to contain hemoglobin subunit. In summary, this work provided a rapid and sensitive tool for screening metal containing proteins in large number of biological samples.

3D printing of TiO2 nano particles containing macrostructures for As(III) removal in water.

Nanomaterials play a crucial role in various areas due to their extraordinary chemical and physical properties. Loading microscopic nanomaterials onto macrostructures is inevitable for their implementation from laboratory experiments to practical applications. Nevertheless, the geometries of conventional supporting structures are usually limited and nanomaterials are easy to be inhomogeneously distributed, aggregated, and lost. Therefore, controllably configuring nanomaterials into sophisticated three-dimensional macroscopic structures without sacrificing their inherent properties remains challenging. Here we utilize the advantages of 3D printing technology to realize this purpose. As a proof-of-concept, the application of 3D stereolithography printed macrostructures containing TiO2 nano particles (TiO2 NPs) for direct adsorption removal of As(III) in water was demonstrated. The morphology and distribution of TiO2 NPs mounted on printed macrostructures were initially characterized. Then batch adsorption experiments were conducted to investigate the effect of the 3D printing process, TiO2 NPs doped concentration and TiO2 NP size as well as adsorption kinetics and isotherms. We also demonstrated that 3D printed adsorption structures could be easily reused over 10 times and were effective for raw arsenic-polluted groundwater samples. Our findings show that 3D printing provides a promising route to design and fabricate customized macrostructures endowed with specific properties of nanomaterials.

Sensitive determination of metalloprotein in salt-rich matrices by size exclusion chromatography coupled with inductively coupled plasma-mass spectrometry.

Metalloproteins play crucial and distinct roles in a variety of biological processes that rely heavily on the metal ions and various proteins. However, there is still a lack of method for rapid analysis of metalloproteins in complex samples, especially in salt-rich matrices. In this study, a sensitive method for separation and determination of metalloproteins in salt-rich matrices was developed based on the size exclusion chromatography coupled with inductively coupled plasma-mass spectrometry (SEC-ICP-MS), combining with the high matrix introduction (HMI) mode, which is quite essential for biological system. The separation conditions of the SEC-ICP-MS system were optimized by using four iodine labeled proteins with different molecular weights, including bovine serum albumin (BSA, 66.0 kDa), ovalbumin (OVA, 44.0 kDa), carbonic anhydrase (CA, 29.0 kDa) and ribonuclease A (RA, 13.7 kDa). After optimization, four iodine labeled proteins and iodine ions were successfully separated within 30 min by using 10 mmol/L HEPES and 40 mmol/L Na2SO4 (pH=7.0) as mobile phase and a linear relationship between log molecular weight and retention time was established. The relative standard deviations (RSDs, n = 5) of the retention time and peak areas for the four iodine labeled proteins were in the range of 0.2-0.9% and 3.3-7.7%, respectively, suggesting good precision and repeatability. Then the proposed method was successfully applied to the rapid separation and detection of lead-binding proteins in real biological tissue samples.

Two Typical Glycosylated Metabolites of Tetrabromobisphenol A Formed in Plants: Excretion and Deglycosylation in Plant Root Zones.

The glycosylation process was investigated for the common brominated flame retardant tetrabromobisphenol A (TBBPA) in hydroponic exposure systems with pumpkin seedlings. Two typical glycosylation metabolites of TBBPA formed in pumpkin seedlings, TBBPA mono-ß-d-glucopyranoside (TBBPA MG) and TBBPA di-ß-d-glucopyranoside (TBBPA DG), increasing their mass early in the exposure (reaching maximum masses of 608 ± 53 and 3806 ± 1570 pmol at 12 h, respectively) and then falling throughout exposure. These two metabolites were released from roots to rhizosphere solutions, where they also exhibited initial increases followed by decreasing trends (reaching maximum masses of 595 ± 272 pmol at 3 h and 77.1 ± 36.0 pmol at 6 h, respectively). However, a (pseudo)zero-order deglycosylation of TBBPA MG and TBBPA DG (during the first 1.5 h) back to TBBPA was unexpectedly detected in the hydroponic solutions containing pumpkin exudates and microorganisms. The function of microorganisms in the solutions was further investigated, revealing that the microorganisms were main contributors to deglycosylation. Plant detoxification through glycosylation and excretion, followed by deglycosylation of metabolites back to the toxic parent compound (TBBPA) in hydroponic solutions, provides new insight into the uptake, transformation, and environmental fate of TBBPA and its glycosylated metabolites in plant/microbial systems.

Tunable spectrum resemblance of LED lights for improving the photosynthetic action of Chinese Cabbages.

To increase efficiency, and reduce energy loss and waste, we propose to improve the photosynthetic action spectrum resemblance (SRPAS) of LED light with the absorption spectra of the fresh leaf, for accelerating the growth of Chinese Cabbages. Eight spectral LED lights were adopted to irradiate Chinese Cabbages under 150 µmol•m-2 s-1 for a 16 hd-1 photoperiod. Of these, under the irradiation of blue + broad red + more yellow (BRY2) light with high spectrum resemblance of 75%, the fresh weight and dry weight are 5.1times and 3.0 times, respectively, and the leaf area and leaf number are 1.7 times, as high as under the blue light. The results demonstrate that the optimized LED light can be presumed to have the highest spectrum resemblance (SRPAS) with the absorption spectra of Chinese Cabbages, and the highest energy-conversion efficiency. These conclusions may be of great benefit to further assess and find either an ideal light applied for plant growth or design of better light sources for growing different plants.

Uplink Scheduling of Navigation Constellation Based on Immune Genetic Algorithm.

The uplink of navigation data as satellite ephemeris is a complex satellite range scheduling problem. Large-scale optimal problems cannot be tackled using traditional heuristic methods, and the efficiency of standard genetic algorithm is unsatisfactory. We propose a multi-objective immune genetic algorithm (IGA) for uplink scheduling of navigation constellation. The method focuses on balance traffic and maximum task objects based on satellite-ground index encoding method, individual diversity evaluation and memory library. Numerical results show that the multi-hierarchical encoding method can improve the computation efficiency, the fuzzy deviation toleration method can speed up convergence, and the method can achieve the balance target with a negligible loss in task number (approximately 2.98%). The proposed algorithm is a general method and thus can be used in similar problems.