Figure 1 Changes of faecal microbial communities in different stages (acute, convalescence, postconvalescence) of patients with COVID-19 (n=30), compared with uninfected controls (n=30). (A) α-Diversity, illustrated by microbiota richness (Chao 1 index), was reduced in COVID-19 (p<0.01, Wilcoxon rank-sum test). Boxes represent the 25th-75th percentile of the distribution; the median is shown as a thick line in the middle of the box; whiskers extend to values with 1.5 times the difference between the 25th and 75th percentiles. ***P<0.001. (B) Principal coordinate analysis (PCoA) of Bray-Curtis distance analysis demonstrated that the overall microbial composition of patients with COVID-19 deviated from the uninfected controls (analysis of similarities, R = -0.201, p=0.001). (C) The same PCoA plot as (B), coloured by α-diversity measured by Chao 1 index.

A total of 264 nonduplicate strains of imipenem (IPM)-nonsusceptible Pseudomonas aeruginosawere isolated from hospitals in 16 different regions throughout China. These 264 IPM-nonsusceptible clinical isolates of P. aeruginosa were examined by PCR, a metallo-␤-lactamase (MBL) Etest, a double-disk synergy test (DDST), and a test using combined IPM disks supplemented with various amounts of EDTA. A total of 24 strains positive for MBLs were confirmed by PCR and DNA sequence analysis: 10 strains positive for the bla VIM-2 gene, 13 strains positive for the bla IMP-9 gene, and 1 strain positive for the bla IMP-1 gene. Real-time reverse transcriptase PCR (RT-PCR) was used to verify whether the isolates harboring MBL genes produced the enzyme and was considered the standard for evaluation of the methodology in this study. Of these 24 MBL-positive stains, 21 were confirmed as MBL-producing strains by real time RT-PCR for MBL expression and the other 3 had no expression of MBLs. The sensitivities, specificities, and positive and negative predictive values for the MBL Etest, the DDST, and the combined disk (CD) assay were evaluated. The best method for screening for MBL production in P. aeruginosa strains from China was the CD assay (IMP-EDTA) using 750 g of EDTA/disk with a breakpoint of >6 mm. In the CD assay (IPM-EDTA) with 290 g and 750 g EDTA, the zone diameter increases for VIM-2-producing P. aeruginosa isolates were greater than those for IMP-9-producing P. aeruginosa isolates (P ‫؍‬ 0.00).The worldwide spread of acquired metallo-␤-lactamases (MBLs) in clinically important pathogens, such as Pseudomonas spp., Acinetobacter spp., and members of the Enterobacteriaceae family, has become a great concern (9, 12). Increased mortality rates have been documented for patients infected with MBL-producing Pseudomonas aeruginosa, and these rates are especially due to inadequate empirical therapy (27). Most of the MBL-encoding genes reside on class 1 integrons and plasmids that usually confer high mobility to these genetic elements (8,17,22,24,26). Therefore, early detection of MBL-producing organisms is of crucial importance for prevention of their inter-and intrahospital dissemination, not only in institutions with high prevalences of such isolates but also in those in which phenotypes of resistance have never been detected. Various criteria for screening for MBL production in P. aeruginosa have been suggested (15). Currently, the most widely accepted standardized MBL functional screen is the MBL Etest (AB BioDisk, Solna, Sweden). However, due to the high cost and unavailability of Etest strips, many clinical microbiology laboratories use alternative screening methods, such as the double-disk synergy test (DDST) and the combined disk (CD) assay. Although the DDST and the CD assay are simple to perform and cheaper than the MBL Etest, they have shown discordant results, depending on the employed methodology, ␤-lactam substrates, MBL inhibitors (IMBL), and bacterial genus tested (7,11,14,15). Standardization of a phenotypic meth...

Background The gut microbiota plays an important role in shaping the immune system and may be closely connected to the development of allergic diseases. Objective This study aimed to determine the gut microbiota composition in Chinese allergic rhinitis (AR) patients as compared with healthy controls (HCs). Methods We collected stool samples from 93 AR patients and 72 age- and sex-matched HCs. Gut microbiota composition was analyzed using QIIME targeting the 16S rRNA gene. Functional pathways were predicted using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States. Statistical analysis was performed using the R program, linear discriminant analysis effect size (LefSe), analysis of QIIME, and statistical analysis of metagenomic profiles, among other tests. Results Compared with HCs, AR patients had significantly lower gut-microbiota α-diversity ( P < .001). The gut microbiota composition significantly differed between the 2 study groups. At the phylum level, the relative abundance of Bacteroidetes was higher while those of Actinobacteria and Proteobacteria were lower in the AR group than in the HC group ( P < .001, q < 0.001). At the genus level, Escherichia-Shigella, Prevotella, and Parabacteroides ( P < .001, q < 0.001) had significantly higher relative abundances in the AR group than in the HC group. LefSe analysis indicated that Escherichia-Shigella, Lachnoclostridium, Parabacteroides, and Dialister were potential biomarkers for AR. In addition, predictive metagenome functional analysis showed that pyruvate, porphyrin, chlorophyll, purine metabolism, and peptidoglycan biosynthesis significantly differed between the AR and HC groups. Conclusion A comparison of the gut microbiota of AR patients and HCs suggested that dysbiosis of the fecal microbiota is involved in the development of AR. The present results may reveal key differences and identify targets for preventive or therapeutic intervention.

Arbuscular mycorrhizal fungi (AMF) promote plants to absorb more water and nutrients and improve their stress resistance. As the main signal transducer, the mitogen‐activated protein kinase (MAPK) cascade plays a vital role in drought stress. However, how the MAPK family genes of mycorrhizal plants respond to stress is still not clear. Our study analyzed physiological indexes and expression profiles of MAPK family genes of Populus simonii × P. nigra under two inoculation treatments (inoculated with or without Rhizophagus irregularis) and two water conditions (well‐watered or drought stress). The results showed that the stronger photosynthesis of mycorrhizal plants may be mediated by MAPK genes induced by AMF. Mycorrhizal plants showed lower oxidative damage and drought sensitivity. Mycorrhiza downregulated the expression of PsnMAPK7‐2, PsnMAPK16‐1, PsnMAPK19‐2, and PsnMAPK20‐2 which negatively regulate drought tolerance and induced specific PsnMAPKs in roots which activate transcription factors to regulate downstream gene expressions, enhancing drought tolerance. This is the first time to identify part of the MAPK gene family of P. simonii × P. nigra at the genome level and study MAPK genes in mycorrhizal forest trees. This is helpful to understand the function of the MAPK gene family in response to drought of mycorrhizal plants and lays a foundation for afforestation by using mycorrhizal saplings.

IntroductionSaline-alkali stress seriously endangers the normal growth of Populus simonii×P. nigra. Arbuscular mycorrhizal (AM) fungi can enhance the saline-alkali tolerance of plants by establishing a symbiotic relationship with them.MethodsIn this study, a pot experiment was conducted to simulate a saline-alkali environment where Populus simonii×P. nigra were inoculated with Funneliformis mosseae to explore their effects on the saline-alkali tolerance of Populus simonii×P. nigra.Results and DiscussionOur results show that a total of 8 NHX gene family members are identified in Populus simonii×P. nigra. F. mosseae regulate the distribution of Na+ by inducing the expression of PxNHXs. The pH value of poplar rhizosphere soil is reduced, result in the promote absorption of Na+ by poplar, that ultimately improved the soil environment. Under saline-alkali stress, F. mosseae improve the chlorophyll fluorescence and photosynthetic parameters of poplar, promote the absorption of water, K+ and Ca2+, thus increase the plant height and fresh weight of aboveground parts, and promote the growth of poplar. Our results provide a theoretical basis for further exploring the application of AM fungi to improve the saline-alkali tolerance of plants.