Effects of elevated carbon dioxide (CO2)and ozone (O3)concentrations on ectoenzyme activities in rice rhizospheric soil.

Rising atmospheric carbon dioxide (CO2) and ozone (O3) concentrations are the main global change drivers. Soil ectoenzymes play an important role in maintaining soil ecosystem services. Exploring the responses of soil ectoenzymes to elevated CO2 and O3 concentrations is important for combating global climate change. In this study, we simulated elevated CO2 concentrations (+200 µmol·mol-1, eCO2), elevated O3 concentrations (0.04 µmol·mol-1, eO3), and their combination (eCO2+eO3) in open-top chambers (OTCs), and investigated the responses of rhizospheric soil ectoenzyme activities. The results showed that eCO2 significantly increased the ß-D-Glucosidase (ßG) activity by 73.0%, and decreased that of polyphenol oxidase (PHO), peroxidase (PEO), and acid phosphatase (AP) by 48.9%, 46.6% and 72.9% respectively, but did not affect that of cellulose hydrolase (CBH) and ß-N-Acetylglucosaminidase (NAG). eO3 significantly reduced the activities of CBH and AP by 34.2% and 30.4%, respectively. The activities of PHO and AP were reduced by 87.3% and 32.3% under the eCO2+eO3 compared with the control, respectively. Results of the principal coordinate analysis, permutation multivariate analysis of variance and redundancy analysis showed that both elevated CO2 and O3 significantly affected soil ectoenzyme activities, with stronger effects of elevated CO2 than elevated O3. Root nitrogen content, root carbon to nitrogen ratio, soil microbial biomass carbon and nitrate nitrogen were the main drivers of soil ectoenzyme activities under elevated CO2 and O3. Elevated O3 could partially neutralize the effects of elevated CO2 on soil ectoenzyme activities. In conclusion, elevated CO2 and O3 restrained the activities of most soil ectoenzyme, suggesting that climate change would threat soil ecosystem services and functions in the agroecosystem.

Effects of common afforestation tree species on soil bacterial community and microbial functional guilds in subtropical forests.

To understand the effects of common afforestation tree species on soil microbial community in subtropical forests, seven different tree species were selected as the research object, including Pinus massoniana, Mytilaria laosensis, Liquidambar formosana, Ilex chinensis, Michelia macclurei, Quercus acutissima and Betula luminifera. Based on 16S rRNA high-throughput sequencing and real-time quantitative PCR techniques, we explored the effects of different tree species on soil bacterial community composition, diversity and microbial functional guilds. The results showed that Acidobacteria, Proteobacteria, and Actinobacteria were the dominant bacterial phyla, and that there was no significant difference in bacterial diversity or richness index among different tree species. Results of redundancy analysis suggested that soil bulk density, soil C/N, litter nitrogen content, and litter C/N were the predominant factors determining soil bacterial community composition. The afforestation tree species had significant effects on functional gene abundances of ammonia oxidizing archaea, ammonia oxidizing bacteria and complete ammonia oxidation. Comammox were dominant in abundance. Ammonia oxidizing archaea amoA gene was the only type whose abundance showed significant correlation with soil nitrate content, suggesting that ammonia oxidizing archaea could play a dominant role in the autotrophic nitrification in the acidic subtropical forest soils. The afforestation tree species had significant effects on functional gene abundances of ammonia oxidizing microorganisms. Results of correlation analysis showed that litter nitrogen content was the driving factor for the abundance of ammonia oxidizing microorganisms. Our study provided strong evidence that the responses of soil microbial functional guilds to tree species were more sensitive than bacterial community composition. Future studies should explore the mechanisms of tree plantations on forest ecosystem functioning from the perspective of microbial functional guilds.

Simplifying network complexity of soil bacterial community exposed to short-term carbon dioxide and ozone enrichment in a paddy soil.

Global atmospheric changes are characterized by increases in carbon dioxide (CO2) and ozone (O3) concentrations, with important consequences for the soil microbial community. However, the influences of CO2 and O3 enrichment on the biomass, diversity, composition, and functioning of the soil bacterial community remain unclear. We investigated the effects of short-term factorial combinations of CO2 (by 200 ppm) and O3 (by 40 ppb) enrichment on the dynamics of soil bacterial community in paddy soils with two rice varieties (Japonica, Nangeng 5055 (NG5055) vs. Wuyujing 3 (WYJ3)) in an open top chamber facility. When averaged both varieties, CO2 and O3 enrichment showed no individual or combined effect on the abundance or diversity of soil bacterial community. Similarly, CO2 enrichment did not exert any significant effect on the relative abundance of bacterial phyla. However, O3 enrichment significantly reduced the relative abundance of Myxococcota phylum by a mean of 37.5%, which negatively correlated to root N content. Compared to ambient conditions, soil bacterial community composition was separated by CO2 enrichment in NG5055, and by both CO2 and O3 enrichment in WYJ3, with root N content identified as the most influential factor. These results indicated that root N was the top direct predictor for the community composition of soil bacteria. The COG (cluster of orthologous groups) protein of cell motility was significantly reduced by 5.8% under CO2 enrichment, and the COG protein of cytoskeleton was significantly decreased by 14.7% under O3 enrichment. Furthermore, the co-occurrence network analysis indicated that both CO2 and O3 enrichment decreased the network complexity of the soil bacterial community. Overall, our results highlight that continuous CO2 and O3 enrichment would potentially damage the health of paddy soils through adverse impacts on the associations and functional composition of soil microbial communities.

A Robust Visual Tracking Method Based on Reconstruction Patch Transformer Tracking.

Recently, the transformer model has progressed from the field of visual classification to target tracking. Its primary method replaces the cross-correlation operation in the Siamese tracker. The backbone of the network is still a convolutional neural network (CNN). However, the existing transformer-based tracker simply deforms the features extracted by the CNN into patches and feeds them into the transformer encoder. Each patch contains a single element of the spatial dimension of the extracted features and inputs into the transformer structure to use cross-attention instead of cross-correlation operations. This paper proposes a reconstruction patch strategy which combines the extracted features with multiple elements of the spatial dimension into a new patch. The reconstruction operation has the following advantages: (1) the correlation between adjacent elements combines well, and the features extracted by the CNN are usable for classification and regression; (2) using the performer operation reduces the amount of network computation and the dimension of the patch sent to the transformer, thereby sharply reducing the network parameters and improving the model-tracking speed.

Aryl Hydrocarbon Receptor Suppresses the Prostate Cancer LNCaP Cell Growth and Invasion by Promoting DNA Damage Response Under Oxidative Stress.

Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that interacts with multiple signaling pathways during prostate development. In the present study, LNCaP cells were knocked down of AhR by siRNA, or treated with the AhR agonist 3-methylcholanthrene (3MC). The effects of AhR on LNCaP cells and the associated mechanisms were studied both under normal condition and under hydrogen peroxide (H2O2)-induced oxidative stress. MTT, transwell chamber assays and flow cytometry were employed to investigate cell proliferation, invasion, and apoptosis, respectively, whereas the DNA damage response (DDR) signaling (phosphorylation of ataxia-telangiectasia mutated [ATM], check-point kinase 2 [Chk2], histone H2AX, p53, and cleaved poly-ADP-ribose polymerase [PARP]) was detected by western blotting. Exposure of LNCaP cells to H2O2 inhibited their viability and migration, and induced apoptosis, at a greater extent compared with the culture under normal conditions. In addition, the oxidative stress increased p-ATM, p-Chk2, p-p53, and p-H2AX expression levels significantly. Knockdown of AhR attenuated the aforementioned effects caused by H2O2-induced oxidative stress. Activation of AhR by 3MC treatment, further aggravated these changes of LNCaP cells on oxidative stress. The findings indicated that AhR suppresses the viability and migration of LNCaP cells notably under oxidative stress, and this process is associated with positive regulation of the responses to oxidative DNA damage.

[Improvement on flame atomic absorption spectrometry for determining Tin concentration in air of workplaces].

OBJECTIVE: To explore the influence factors on determining Tin concentration in air of workplaces with flame atomic absorption spectrometry and to establish an accurate, sensitive and high-efficient method. METHODS: The different reagents were used to digest the sampling filter membranes and the determining conditions of flame atomic absorption spectrometry were adjusted, then the determining results were compared. RESULTS: When 3 ml hydrochloric acid and 0.5 ml nitric acid served as the digesting reagents and the determining conditions of flame atomic absorption spectrometry were adjusted to the best conditions, there was the good linearity in the tested concentration range of Tin, the correlation coefficient was larger than 0.9990. The limit of quantification was 1.0 p.g/ml. The extraction recovery was between 99.6%-102.6%, and the RSD were all less than 5.0%. CONCLUSION: The proper kinds and quantity of digestive reagents in pretreatment of the samples should be chosen for the accuracy and precision of the determination according to the influence factors of determination.