Phosphate-solubilizing bacteria improve the antioxidant enzyme activity of Potamogeton crispus L. and enhance the remediation effect on Cd-contaminated sediment.

Phosphorus-solubilizing bacteria (PSB) assisted phytoremediation of cadmium (Cd) pollution is an effective method, but the mechanism of PSB-enhanced in-situ remediation of Cd contaminated sediment by submerged plants is still rare. In this study, PSB (Leclercia adecarboxylata L1-5) was inoculated in the rhizosphere of Potamogeton crispus L. (P. crispus) to explore the effect of PSB on phytoremediation. The results showed that the inoculation of PSB effectively improved the Cd extraction by P. crispus under different Cd pollution and the Cd content in the aboveground and underground parts of P. crispus all increased. The µ-XRF images showed that most of the Cd was enriched in the roots of P. crispus. PSB especially showed positive effects on root development and chlorophyll synthesis. The root length of P. crispus increased by 51.7 %, 80.5 % and 74.2 % under different Cd pollution, and the Ca/Cb increased by 38.9 %, 15.2 % and 8.6 %, respectively. Furthermore, PSB enhanced the tolerance of P. crispus to Cd. The contents of soluble protein, MDA and H2O2 in 5 mg·kg-1 and 7 mg·kg-1 Cd content groups were decreased and the activities of antioxidant enzymes were increased after adding PSB. The results showed that the application of PSB was beneficial to the in-situ remediation of submerged plants.

Bilingual Language Control in the Brain: Evidence from Structural and Effective Functional Brain Connectivity.

Experience in bilingual language control is often accompanied by changes in the structure and function of the brain. Brain structural changes are also often closely related to changes in functions. Previous studies, however, have not directly explored the relationship between structural connectivity and effective functional connectivity of the brain during bilingual language control, and whether the two types of connectivity are associated with behavioral performance of language control. Using behavioral performance, functional, and diffusion imaging techniques, we found that: (1) during language control, the left dorsal lateral prefrontal cortex (dlPFC), left caudate nucleus (CN), inferior parietal lobe, precuneus, and dorsal anterior cingulate cortex (dACC)/pre-SMA were significantly activated. (2) In the language control model with left dlPFC, dACC/pre-SMA, and left CN as ROIs (selected based on activation results and language control models from previous studies), stimuli first enter dACC/pre-SMA and then to left CN. At the left CN, a bidirectional effective connectivity is formed with left dlPFC. (3) There is a nonlinear relationship between effective connectivity during language control and the structural connectivity of the second language learners' brains. Specifically, the fiber density between dACC/pre-SMA and left dlPFC has a positive influence on the bidirectional effective connectivity between left dlPFC and left CN. Findings of the present study contribute evidence toward functional effective connectivity during bilingual language control; toward structural connectivity in the brains of second language learners; as well as toward nonlinear relationships between functional effective connectivity, structural connectivity, and behavioral performance in relation to bilingual language control.

Individual differences in internal models explain idiosyncrasies in scene perception.

According to predictive processing theories, vision is facilitated by predictions derived from our internal models of what the world should look like. However, the contents of these models and how they vary across people remains unclear. Here, we use drawing as a behavioral readout of the contents of the internal models in individual participants. Participants were first asked to draw typical versions of scene categories, as descriptors of their internal models. These drawings were converted into standardized 3d renders, which we used as stimuli in subsequent scene categorization experiments. Across two experiments, participants' scene categorization was more accurate for renders tailored to their own drawings compared to renders based on others' drawings or copies of scene photographs, suggesting that scene perception is determined by a match with idiosyncratic internal models. Using a deep neural network to computationally evaluate similarities between scene renders, we further demonstrate that graded similarity to the render based on participants' own typical drawings (and thus to their internal model) predicts categorization performance across a range of candidate scenes. Together, our results showcase the potential of a new method for understanding individual differences - starting from participants' personal expectations about the structure of real-world scenes.

Response of rumen microorganisms to pH during anaerobic hydrolysis and acidogenesis of lignocellulose biomass.

Rumen microorganisms can efficiently degrade lignocellulosic wastes to produce volatile fatty acids (VFAs). pH is a key factor in controlling the type and yield of VFAs by affecting the microorganisms involved in rumen fermentation. However, the effects of different pH on rumen microbial diversity, communities, and mechanisms are unclear. In this study, the hydrolysis and acidogenesis of corn straw and diversity, communities, and mechanisms of rumen microorganisms were explored at different initial pHs. Results showed that the highest hemicellulose, cellulose, and lignin degradation efficiency of corn straw was 55.2 %, 38.3 %, and 7.01 %, respectively, and VFA concentration was 10.2 g/L at pH 7.0. Low pH decreased the bacterial diversity and increased the fungal diversity. Rumen bacteria and fungi had different responses to initial pHs, and the community structure of bacteria and fungi had obviously differences at the genus level. The core genera Succiniclasticum, Treponema, and Neocallimastix relative abundance at initial pH 7.0 samples were significantly higher than that at lower initial pHs, reaching 6.01 %, 1.61 %, and 5.35 %, respectively. The bacterial network was more complex than that of fungi. pH, acetic acid, and propionic acid were the main factors influencing the bacterial and fungal community structure. Low pH inhibited the expression of functional genes related to hydrolysis and acidogenesis, explaining the lower hydrolysis and acidogenesis efficiency. These findings will provide a better understanding for rumen fermentation to produce VFAs.

Anaerobic syntrophic system composed of phosphate solubilizing bacteria and dissimilatory iron reducing bacteria induces cadmium immobilization via secondary mineralization.

Secondary mineralization is a promising method for remediating cadmium (Cd) pollution in sediments, but the poor stability of Cd-containing secondary minerals is a bottleneck that limits the development of this approach. The existence of phosphate can enhance the formation of stable secondary minerals and points a new direction for Cd immobilization. In this research, a novel syntrophic system composed of phosphate solubilizing bacteria (PSB) and dissimilatory iron reducing bacteria (DIRB) was established and the effect and mechanism of Cd immobilization in the system were also explored. The results showed that under the conditions of DIRB:PSB (V:V)= 3:1, syntrophic bacteria dosage of 5% and glucose dosage of 5 g/L, Cd incorporated in the secondary minerals could account for about 60% of the total Cd. In the pH range of 5-9, alkaline environment was conducive to the immobilization of Cd and the percentage of combined Cd was up to 58%, while the combined Cd in secondary minerals decreased from 62% to 56% with the increase of initial Cd concentration from 0.1 to 0.3 mmol/L. In addition, XRD, XPS, Mössbauer and other characterization results showed that secondary minerals, such as Cd exchange hydroxyapatite (Cd-HAP) and kryzhanovskite (Fe3(PO4)2(OH)3) were formed in this new system. The established syntrophic system of PSB and DIRB is thus a prospective bioremediation technology for Cd immobilization in sediments and can avoid the potential risk might be caused by the addition of phosphorus-containing materials.

Humic acid and fulvic acid facilitate the formation of vivianite and the transformation of cadmium via microbially-mediated iron reduction.

The effects of humic acids (HA) and fulvic acids (FA) on the fate of Cd in anaerobic environment upon microbial reduction of Cd-bearing ferrihydrite (Fh) with Geobacter metallireducens were investigated. The results showed that HA and FA could promote the reductive dissolution of Fh and the formation of vivianite. After incubation of 38 d, vivianite accounted for 47.19%, 59.22%, and 48.53% of total Fe in biological control batch (BCK), HA and FA batches (C/Fe molar ratio of 1.0), respectively, by Mössbauer spectroscopy analysis. In terms of Cd, HA and FA could promote the release of adsorbed Cd during the initial bioreduction process, but reassuringly, after 38 d the dissolved Cd with HA and FA addition batches were 0.58-0.91 and 0.99-1.08 times of the BCK, respectively. The proportions of residual Cd in HA batches were higher than FA and BCK batches, indicating that HA was better than FA in immobilizing Cd. This might be because the quinone groups in HA could act as electron shuttle. This study showed that HA facilitated the transformation of vivianite better than FA, and Cd can be stabilized by resorption or co-precipitation with vivianite, providing a theoretical support for the translocation of Cd in sediment-water interface.

Noval porous phosphate-solubilizing bacteria beads loaded with BC/nZVI enhanced the transformation of lead fractions and its microecological regulation mechanism in soil.

Soil lead pollution becomes a serious environmental problem. Microbial remediation has received widespread attentions due to high efficiency and no secondary pollution. In this research, a noval porous spherical phosphate-solubilizing bacteria bead loaded with biochar/nZVI (Bio-bead) was used to passivate lead in soil, and the effects and microecological regulation mechanisms of this process were also investigated. The results showed that the pH, OM, and AP of soil in the Bio-bead group were increased and the ORP was decreased over time compared with the blank group. The proportion of stable (oxidizable and residue) fractions of lead in Bio-bead group (45%) was much higher than that of the blank group (35%). In addition, the result of microbial community structure showed that Bio-beads did not change the species of dominant bacterial, excepting the abundance of Pseudomonas increased significantly and the abundance of Sphingomonas reduced during remediation. Redundancy analysis showed that pH, OM, AP and the ratio of residual and oxidizable fractions lead in soil were positively correlated with the abundance of Pseudomonas, while ORP was negatively correlated with the abundance of Pseudomonas. These findings have proved that Bio-bead is a potential strategy for remediation of lead-contaminated soil even in complexed soils.

Impact of selenium on rhizosphere microbiome of a hyperaccumulation plant Cardamine violifolia.

Cardamine violifolia is the only selenium hyperaccumulation plant found in China. It has been developed as a source of medicinal and edible products that we can consume as selenium supplements. Many planting approaches have been developed to increase the selenium content of C. violifolia for nutrient biofortification. However, the contribution of rhizosphere microbes of C. violifolia to selenium enrichment has not been investigated. In this study, four types of selenium, i.e., selenate, selenite, nanoparticles selenium from Bacillus subtilis (B. subtilis-Se), and organic selenium from yeast (yeast-Se), were added to the soil that C. violifolia was grown in, respectively. Selenate led to the greatest accumulation of selenium in C. violifolia, followed by selenite, B. subtilis-Se, and yeast-Se. Except for yeast-Se, the concentration of selenium in C. violifolia positively correlated with the amount of selenium added to the soil. Furthermore, the different types of exogenous selenium exhibited distinct effects on the rhizosphere microbiome of C. violifolia. Alpha and beta diversity analyses demonstrated that rhizosphere microbiome was more obviously affected by selenium from B. subtilis and yeast than from selenate and selenite. Different microbial species were enriched in the rhizosphere of C. violifolia under various exogenous selenium treatments. B. subtilis-Se application enhanced the abundance of Leucobacter, Sporosarcina, Patulibacter, and Denitrobacter, and yeast-Se application enriched the abundance of Singulishaera, Lactobacillus, Bdellovibrio, and Bosea. Bosea and the taxon belonging to the order Solirubrobacterales were enriched in the samples with selenate and selenite addition, respectively, and the abundances of these were linearly related to the concentrations of selenate and selenite applied in the rhizosphere of C. violifolia. In summary, this study revealed the response of the rhizosphere microbiome of C. violifolia to exogenous selenium. Our findings are useful for developing suitable selenium fertilizers to increase the selenium hyperaccumulation level of this plant.

Sodium Selenite Enhances Antibiotics Sensitivity of Pseudomonas aeruginosa and Deceases Its Pathogenicity by Inducing Oxidative Stress and Inhibiting Quorum Sensing System.

Pseudomonas aeruginosa, a Gram-negative opportunistic pathogen, is commonly found in clinical settings and immuno-compromised patients. It is difficult to be eradicated due to its strong antibiotic resistance, and novel inactivation strategies have yet to be developed. Selenium is an essential microelement for humans and has been widely used in dietary supplement and chemoprevention therapy. In this study, the physiological and biochemical effects of sodium selenite on P. aeruginosa PAO1 were investigated. The results showed that 0~5 mM sodium selenite did not impact the growth of PAO1, but increased the lethality rate of PAO1 with antibiotics or H2O2 treatment and the antibiotics susceptibility both in planktonic and biofilm states. In addition, sodium selenite significantly reduced the expression of quorum sensing genes and inhibited various virulence factors of this bacterium, including pyocyanin production, bacterial motilities, and the type III secretion system. Further investigation found that the content of ROS in cells was significantly increased and the expression levels of most genes involved in oxidative stress were up-regulated, which indicated that sodium selenite induced oxidative stress. The RNA-seq result confirmed the phenotypes of virulence attenuation and the expression of quorum sensing and antioxidant-related genes. The assays of Chinese cabbage and Drosophila melanogaster infection models showed that the combination of sodium selenite and antibiotics significantly alleviated the infection of PAO1. In summary, the results revealed that sodium selenite induced oxidative stress and inhibited the quorum sensing system of P. aeruginosa, which in turn enhanced the antibiotic susceptibility and decreased the pathogenicity of this bacterium. These findings suggest that sodium selenite may be used as an effective strategy for adjunct treatment of the infections caused by P. aeruginosa.

Bilingualism and domain-general cognitive functions from a neural perspective: A systematic review.

A large body of research has indicated that bilingualism - through continual practice in language control - may impact cognitive functions, as well as relevant aspects of brain function and structure. The present review aimed to bring together findings on the relationship between bilingualism and domain-general cognitive functions from a neural perspective. The final sample included 210 studies, covering findings regarding neural responses to bilingual language control and/or domain-general cognitive tasks, as well as findings regarding effects of bilingualism on non-task-related brain function and brain structure. The evidence indicates that a) bilingual language control likely entails neural mechanisms responsible for domain-general cognitive functions; b) bilingual experiences impact neural responses to domain-general cognitive functions; and c) bilingual experiences impact non-task-related brain function (both resting-state and metabolic function) as well as aspects of brain structure (both macrostructure and microstructure), each of which may in turn impact mental processes, including domain-general cognitive functions. Such functional and structural neuroplasticity associated with bilingualism may contribute to both cognitive and neural reserves, producing benefits across the lifespan.

Deriving water quality criteria for China for the organophosphorus pesticides dichlorvos and malathion.

Organophosphorus pesticides are effective, cheap, and used extensively but can harm aquatic organism and human health. Here, water quality criteria (WQCs) for dichlorvos (DDVP) and malathion (MAL) were derived. Nine aquatic organisms native to China were used in toxicity tests. Published toxicity data for aquatic organisms native and non-native to China were also analyzed. DDVP and MAL WQCs were derived using (log-normal model) species sensitivity distributions. Species sensitivity distribution curves indicated native and non-native species have different sensitivities to DDVP. The sensitivities of native and non-native species to MAL were not different because non-native species data for fewer than eight genera were available, so further research is required. The results indicated that native species need to be considered when deriving WQCs. The criteria maximum concentration (CMC) and criteria continuous concentration (CCC) were 1.33 and 0.132 µg/L, respectively, for DDVP, and 0.100 and 0.008 µg/L, respectively, for MAL. The CMCs for DDVP and MAL derived using ETX 2.0 software and species sensitivity ranks were different from the CMCs obtained using the SSD method because of parameter uncertainties. The DDVP and MAL WQCs were significantly lower than Chinese surface water quality standard thresholds. The results provide basic data for revising these thresholds.