Response of Juvenile Saccharina japonica to the Combined Stressors of Elevated pCO2 and Excess Copper.

Coastal macroalgae may be subjected to global and local environmental stressors, such as ocean acidification and heavy-metal pollution. We investigated the growth, photosynthetic characteristics, and biochemical compositions of juvenile sporophytes of Saccharina japonica cultivated at two pCO2 levels (400 and 1000 ppmv) and four copper concentrations (natural seawater, control; 0.2 µM, low level; 0.5 µM, medium level; and 1 µM, high level) to better understand how macroalgae respond to ongoing environmental changes. The results showed that the responses of juvenile S. japonica to copper concentrations depended on the pCO2 level. Under the 400 ppmv condition, medium and high copper concentrations significantly decreased the relative growth rate (RGR) and non-photochemical quenching (NPQ) but increased the relative electron transfer rate (rETR) and chlorophyll a (Chl a), chlorophyll c (Chl c), carotenoid (Car), and soluble carbohydrate contents. At 1000 ppmv, however, none of the parameters had significant differences between the different copper concentrations. Our data suggest that excess copper may inhibit the growth of juvenile sporophytes of S. japonica, but this negative effect could be alleviated by CO2-induced ocean acidification.

Decreased Salinity Offsets the Stimulation of Elevated pCO2 on Photosynthesis and Synergistically Inhibits the Growth of Juvenile Sporophyte of Saccharina japonica (Laminariaceae, Phaeophyta).

The combined effect of elevated pCO2 (Partial Pressure of Carbon Dioxide) and decreased salinity, which is mainly caused by freshwater input, on the growth and physiological traits of algae has been poorly assessed. In order to investigate their individual and interactive effects on the development of commercially farmed algae, the juvenile sporophytes of Saccharina japonica were cultivated under different levels of salinity (30, 25 and 20 psu) and pCO2 (400 and 1000 µatm). Individually, decreased salinity significantly reduced the growth rate and pigments of S. japonica, indicating that the alga was low-salinity stressed. The maximum quantum yield, Fv/Fm, declined at low salinities independent of pCO2, suggesting that the hyposalinity showed the main effect. Unexpectedly, the higher pCO2 enhanced the maximum relative electron transport rate (rETRmax) but decreased the growth rate, pigments and soluble carbohydrates contents. This implies a decoupling between the photosynthesis and growth of this alga, which may be linked to an energetic reallocation among the different metabolic processes. Interactively and previously untested, the decreased salinity offset the improvement of rETRmax and aggravated the declines of growth rate and pigment content caused by the elevated pCO2. These behaviors could be associated with the additionally decreased pH that was induced by the low salinity. Our data, therefore, unveils that the decreased salinity may increase the risks of future CO2-induced ocean acidification on the production of S. japonica.

Characteristics of Water-Soluble Inorganic Ions in PM2.5 in Typical Urban Areas of Beijing, China.

Following the implementation of "coal-to-gas conversion" policy in the Haidian District of Beijing during summer, the present comparative study was performed employing 41 PM2.5 samples as precursors to analyze the characteristics of water-soluble inorganic ions. The concentrations of water-soluble inorganic ions in PM2.5 were analyzed by ion chromatography, and the occurrence form of ions was characterized via time-of-flight secondary ion mass spectrometry (TOF-SIMS). Results revealed that the daily average mass concentration of PM2.5 in Beijing during the sampling period was 94.28 ± 52.49 µg/m3. As compared to the winter of 2016, the average daily PM2.5 concentration in Beijing decreased by 29 µg/m3 in 2017 (28.2% decrease), with a remarkable decline in the number of days with pollution. During the pollution period, the concentrations of NO3 -, SO4 2-, and NH4 + were significantly higher in PM2.5 as compared to the cleaning period. The ratio of the concentrations of [NO3 -]/[SO4 2-] was greater than 1, and the contribution from mobile sources was relatively large, indicating that the implementation of the "coal-to-gas conversion" policy in Beijing has led to the reduction of SO4 2- emissions from fixed sources, such as coal. Furthermore, TOF-SIMS analysis results showed that NH4 + tended to exist in the form of molecular ammonium sulfate or ammonium hydrogen sulfate during the period of pollution.

Concentration and speciation of mercury in atmospheric particulates in the Wuda coal fire area, Inner Mongolia, China.

Coal-seam fire is a source of atmospheric mercury that is difficult to control. The Wuda Coalfield in Inner Mongolia, China, is one of the most severe coal fire disaster areas worldwide and has been burning for more than 50 years. To investigate atmospheric mercury pollution from the Wuda coal fire, gaseous elemental mercury (GEM) concentrations and atmospheric particulate mercury (PHg) speciation were measured using a RA-915+ mercury analyzer and the temperature-programmed desorption method. Near-surface GEM concentrations in the Wuda Coalfield and adjacent urban area were 80 ng m-3 (65-90 ng m-3) and 52 ng m-3 (25-95 ng m-3), respectively, which are far higher than the local background value (22 ng m-3). PHg concentrations in the coalfield and urban area also reached significantly high levels, 33 ng m-3 (25-45 ng m-3) and 22 ng m-3 (14-29 ng m-3), respectively (p < 0.05). There is no clear evidence that PHg combines with organic carbon or elemental carbon, but PHg concentration appears to be controlled by air acidity. PHg mainly exists in inorganic forms, such as HgCl2, HgS, HgO, and Hg(NO3)2·H2O. This work can provide references for the speciation analysis of atmospheric PHg and the safety assessment of environmental mercury.

The Effects of 50 nm Unmodified Nano-ZnO on Lipid Metabolism and Semen Quality in Male Mice.

Fifty male mice were exposed to 50 nm unmodified nano-ZnO through intragastric administration for 90 days to detect the long-term effects of unmodified nano-ZnO in mice. Results showed that the blood glucose, serum follicle stimulating hormone, luteinizing hormone, testosterone, and estradiol were significantly decreased (p < 0.05). The serum triglyceride, total cholesterol, and low-density lipoprotein were significantly increased (p < 0.05). The semen quality of the 160 mg/kg·bw group were significantly lowered (p < 0.05). The liver and testis catalase and CuZn-SOD activities were significantly elevated (p < 0.05). The abilities of •OH inhibition in the livers and testes of the 160 mg/kg·bw group were significantly lowered (p < 0.05). The liver and testis MDA levels of the 160 mg/kg·bw group were significantly elevated (p < 0.05). Results indicate that exposure of nano-ZnO could induce lipid metabolism disorder, hyperlipidemia, and reproductive toxicity to male mice through oxidative injury.

Correction to: The Effects of 50 nm Unmodified Nano-ZnO on Lipid Metabolism and Semen Quality in Male Mice.

The original version of this article unfortunately contained a mistake. The correct title should be "The Effects of 50 nm Unmodified Nano-ZnO on Lipid Metabolism and Semen Quality in Male Mice". The original article has been corrected.

CRISPR-assisted multi-dimensional regulation for fine-tuning gene expression in Bacillus subtilis.

Fine-tuning of gene expression is crucial for protein expression and pathway construction, but it still faces formidable challenges due to the hierarchical gene regulation at multiple levels in a context-dependent manner. In this study, we defined the optimal targeting windows for CRISPRa and CRISPRi of the dCas9-α/ω system, and demonstrated that this system could act as a single master regulator to simultaneously activate and repress the expression of different genes by designing position-specific gRNAs. The application scope of dCas9-ω was further expanded by a newly developed CRISPR-assisted Oligonucleotide Annealing based Promoter Shuffling (OAPS) strategy, which could generate a high proportion of functional promoter mutants and facilitate the construction of effective promoter libraries in microorganisms with low transformation efficiency. Combing OAPS and dCas9-ω, the influences of promoter-based transcription, molecular chaperone-assisted protein folding and protease-mediated degradation on the expression of amylase BLA in Bacillus subtilis were systematically evaluated, and a 260-fold enhancement of BLA production was obtained. The success of the OAPS strategy and dCas9-ω for BLA production in this study thus demonstrated that it could serve as a powerful tool kit to regulate the expression of multiple genes multi-directionally and multi-dimensionally in bacteria.

[Research of polysaccharide from Dioscorea opposita Thunb].

OBJECTIVE: To isolate a homogeneous polysaccharide RP from RDP (a crude polysaccharide from Dioscorea opposita Thunb.) , and study its preliminary composition and structure. METHODS: RP was obtained with water extraction, alcohol sedimentation, CTAB deprotein, cellulose column and SephadexG-100 column. The purities of RP were identified by SephadexG-200. PC analysis on its acidic hydrolysates was used to determine the sugar components. Sephadex chromatography was used to mensurate its molecular weight. IR was used to analysis RP. RESULTS: RP was homogeneous. IR indicated that RP had beta configurations. The compositon was identified by paper chromatography as glucose, D-mannose, D-galactose. CONCLUSION: The research could provide a theoretical foundation for further development and utilization.