Short-term exposure to antibiotics begets long-term disturbance in gut microbial metabolism and molecular ecological networks.

BACKGROUND: Antibiotic exposure can occur in medical settings and from environmental sources. Long-term effects of brief antibiotic exposure in early life are largely unknown. RESULTS: Post a short-term treatment by ceftriaxone to C57BL/6 mice in early life, a 14-month observation was performed using 16S rRNA gene-sequencing technique, metabolomics analysis, and metagenomics analysis on the effects of ceftriaxone exposure. Firstly, the results showed that antibiotic pre-treatment significantly disturbed gut microbial α and ß diversities (P < 0.05). Both Chao1 indices and Shannon indices manifested recovery trends over time, but they didn't entirely recover to the baseline of control throughout the experiment. Secondly, antibiotic pre-treatment reduced the complexity of gut molecular ecological networks (MENs). Various network parameters were affected and manifested recovery trends over time with different degrees, such as nodes (P < 0.001, R2 = 0.6563), links (P < 0.01, R2 = 0.4543), number of modules (P = 0.0672, R2 = 0.2523), relative modularity (P = 0.6714, R2 = 0.0155), number of keystones (P = 0.1003, R2 = 0.2090), robustness_random (P = 0.79, R2 = 0.0063), and vulnerability (P = 0.0528, R2 = 0.28). The network parameters didn't entirely recover. Antibiotic exposure obviously reduced the number of key species in gut MENs. Interestingly, new keystones appeared during the recovery process of network complexity. Changes in network stability might be caused by variations in network complexity, which supports the ecological theory that complexity begets stability. Besides, the metabolism profiles of the antibiotic group and control were significantly different. Correlation analysis showed that antibiotic-induced differences in gut microbial metabolism were related to MEN changes. Antibiotic exposure also caused long-term effects on gut microbial functional networks in mice. CONCLUSIONS: These results suggest that short-term antibiotic exposure in early life will cause long-term negative impacts on gut microbial diversity, MENs, and microbial metabolism. Therefore, great concern should be raised about children's brief exposure to antibiotics if the results observed in mice are applicable to humans. Video Abstract.

Effects of dietary arsenic exposure on liver metabolism in mice.

Arsenic, a ubiquitous environmental toxicant with various forms and complex food matrix interactions, can reportedly exert differential effects on the liver compared to drinking water exposure. To examine its specific liver-related harms, we targeted the liver in C57BL/6 J mice (n=48, 8-week-old) fed with arsenic-contaminated food (30 mg/kg) for 60 days, mimicking the rice arsenic composition observed in real-world scenarios (iAsV: 7.3%, iAsIII: 72.7%, MMA: 1.0%, DMA: 19.0%). We then comprehensively evaluated liver histopathology, metabolic changes, and the potential role of the gut-liver axis using human hepatocellular carcinoma cells (HepG2) and microbiota/metabolite analyses. Rice arsenic exposure significantly altered hepatic lipid (fatty acids, glycerol lipids, phospholipids, sphingolipids) and metabolite (glutathione, thioneine, spermidine, inosine, indole-derivatives, etc.) profiles, disrupting 33 metabolic pathways (bile secretion, unsaturated fatty acid biosynthesis, glutathione metabolism, ferroptosis, etc.). Pathological examination revealed liver cell necrosis/apoptosis, further confirmed by ferroptosis induction in HepG2 cells. Gut microbiome analysis showed enrichment of pathogenic bacteria linked to liver diseases and depletion of beneficial strains. Fecal primary and secondary bile acids, short-chain fatty acids, and branched-chain amino acids were also elevated. Importantly, mediation analysis revealed significant correlations between gut microbiota, fecal metabolites, and liver metabolic alterations, suggesting fecal metabolites may mediate the impact of gut microbiota and liver metabolic disorders. Gut microbiota and its metabolites may play significant roles in arsenic-induced gut-liver injuries. Overall, our findings demonstrate that rice arsenic exposure triggers oxidative stress, disrupts liver metabolism, and induces ferroptosis.

[Impact of Climate Warming on Paddy Soil Organic Carbon Change in the Sichuan Basin of China].

Climate warming can increase soil temperature and lead to soil carbon release, but it can also increase soil organic carbon by increasing primary productivity. Cropland soils are considered to have a huge potential to sequester carbon; however, direct observations for the responses of cropland soil organic carbon to climate warming over broad geographic scales are rarely documented. Paddy soil is one of the important cultivated soils in China. Based on the data of 2217 sampling points obtained during the second national soil survey and the data of 2382 sampling points collected during 2017-2019, this study analyzed the change characteristics of soil organic carbon content of paddy surface soil in Sichuan Basin of China and explored the relationships between the soil organic carbon change of paddy soil and temperature, precipitation, cropland use type, fertilization intensity, and grain yield. The results showed that the content of soil organic carbon of paddy soil changed from 13.33 g·kg-1to 15.96 g·kg-1, with an increase of 2.63 g·kg-1, suggesting that soils in the Sichuan Basin have acted as a carbon sink over past 40 years. The soil organic carbon increment of paddy soil varied with different geomorphic regions and different secondary basins. The increase in SOC content in paddy soil was positively correlated with annual average temperature; negatively correlated with annual average precipitation; and initially increased and then decreased with annual average fertilizer application, annual average increase rate of fertilizer application, annual average grain yield, and annual average grain yield growth rate. The relationship between the increase in SOC content and the annual average temperature growth rate was different under different farmland utilizations, and the increase in the annual average temperature growth rate had significant effects with the increase in SOC content only on paddy-dryland rotation. These results indicate that the paddy soil organic carbon change in Sichuan Basin was co-affected by various factors, but climate warming was an important factor leading to the paddy soil organic carbon change, and its influence was controlled by the water conditions determined by farmland use.

A comparison of behavioral paradigms assessing spatial memory in tree shrews.

Impairments in spatial navigation in humans can be preclinical signs of Alzheimer's disease. Therefore, cognitive tests that monitor deficits in spatial memory play a crucial role in evaluating animal models with early stage Alzheimer's disease. While Chinese tree shrews (Tupaia belangeri) possess many features suitable for Alzheimer's disease modeling, behavioral tests for assessing spatial cognition in this species are lacking. Here, we established reward-based paradigms using the radial-arm maze and cheeseboard maze for tree shrews, and tested spatial memory in a group of 12 adult males in both tasks, along with a control water maze test, before and after bilateral lesions to the hippocampus, the brain region essential for spatial navigation. Tree shrews memorized target positions during training, and task performance improved gradually until reaching a plateau in all 3 mazes. However, spatial learning was compromised post-lesion in the 2 newly developed tasks, whereas memory retrieval was impaired in the water maze task. These results indicate that the cheeseboard task effectively detects impairments in spatial memory and holds potential for monitoring progressive cognitive decline in aged or genetically modified tree shrews that develop Alzheimer's disease-like symptoms. This study may facilitate the utilization of tree shrew models in Alzheimer's disease research.

Long-term effects on liver metabolism induced by ceftriaxone sodium pretreatment.

Ceftriaxone is an emerging contaminant due to its potential harm, while its effects on liver are still need to be clarified. In this study, we first pretreated the 8-week-old C57BL/6J mice with high dose ceftriaxone sodium (Cef, 400 mg/mL, 0.2 mL per dose) for 8 days to prepare a gut dysbiosis model, then treated with normal feed for a two-month recovery period, and applied non-targeted metabolomics (including lipidomics) to investigate the variations of fecal and liver metabolome, and coupled with targeted determination of fecal short-chain fatty acids (SCFAs) and bile acids (BAs). Lastly, the correlations and mediation analysis between the liver metabolism and gut metabolism/microbes were carried, and the potential mechanisms of the mal-effects on gut-liver axis induced by Cef pretreatment were accordingly discussed. Compared to the control group, Cef pretreatment reduced the rate of weight gain and hepatosomatic index, induced bile duct epithelial cells proliferated around the central vein and appearance of binucleated hepatocytes, decreased the ratio of total branching chains amino acids (BCAAs) to total aromatic amino acids (AAAs) in liver metabolome. In fecal metabolome, the total fecal SCFAs and BAs did not change significantly while butyric acid decreased and the primary BAs increased after Cef pretreatment. Correlation and mediation analysis revealed one potential mechanism that Cef may first change the intestinal microbiota (such as destroying its normal structure, reducing its abundance and the stability of the microbial network or certain microbe abundance like Alistipes), and then change the intestinal metabolism (such as acetate, caproate, propionate), leading to liver metabolic disorder (such as spermidine, inosine, cinnamaldehyde). This study proved the possibility of Cef-induced liver damage, displayed the overall metabolic profile of the liver following Cef pretreatment and provided a theoretical framework for further research into the mechanism of Cef-induced liver damage.

The gut microbiome promotes arsenic metabolism and alleviates the metabolic disorder for their mammal host under arsenic exposure.

Gut microbiome can participate in arsenic metabolism. However, its efficacy in the host under arsenic stress is still controversial. To clarify their roles in fecal arsenic excretion, tissue arsenic accumulation, host physiological states and metabolism, in this study, ninety-six C57BL/6 male mice were randomly divided to four groups, groups A and B were given sterile water, and groups C and D were given the third generation of broad-spectrum antibiotic (ceftriaxone) to erase the background gut microbiome. Subsequently, groups B and D were subchronicly exposed to arsenic containing feed prepared by adding arsenical mixture (rice arsenic composition) into control feed. In group D, the fecal total arsenic (CtAs) decreased by 25.5 %, iAsIII composition increased by 46.9 %, unclarified As (uAs) composition decreased by 92.4 %, and the liver CtAs increased by 26.7 %; the fecal CtAs was positively correlated with microbial richness and some metabolites (organic acids, amino acids, carbohydrates, SCFAs, hydrophilic bile acids and their derivatives); and fecal DMA was positively correlated with microbial richness and some metabolites (ferulic acid, benzenepropanoic acid and pentanoic acid); network analysis showed that the numbers of modules, nodes, links were decreased and vulnerability was increased; some SCFAs and hydrophilic bile acid decreased, and hydrophobic bile acids increased (Ps < 0.05). In the tissue samples of group D, Il-18 and Ifn-γ gene expression increased and intestinal barrier-related genes Muc2, Occludin and Zo-1 expression decreased (Ps < 0.05); serum glutathione and urine malondialdehyde significantly increased (Ps < 0.05); urine metabolome significantly changed and the variation was correlated with six SCFAs-producing bacteria, and some SCFAs including isobutyric acid, valeric acid and heptanoic acid decreased (Ps < 0.05). Therefore, the normal gut microbiome increases fecal arsenic excretion and biotransformation, which can maintain a healthier microbiome and metabolic functions, and alleviate the metabolic disorder for their mammal host under arsenic exposure.

The fecal arsenic excretion, tissue arsenic accumulation, and metabolomics analysis in sub-chronic arsenic-exposed mice after in situ arsenic-induced fecal microbiota transplantation.

Arsenic can be specifically enriched by rice, and the health hazards caused by high arsenic rice are gradually attracting attention. This study aimed to explore the potential of microbial detoxification via gut microbiome in the treatment of sub-chronic arsenic poisoning. We first exposed mice to high-dose arsenic feed (30 mg/kg, rice arsenic composition) for 60 days to promote arsenic-induced microbes in situ in the gastrointestinal tract, then transplanted their fecal microbiota (FMT) into another batch of healthy recipient mice, and dynamically monitored the microbial colonization by 16S rRNA sequencing and ITS sequencing. The results showed that in situ arsenic-induced fecal microbiome can stably colonized and interact with indigenous microbes in the recipient mice in two weeks, and established a more stable network of gut microbiome. Then, the recipient mice continued to receive high-dose arsenic exposure for 52 days. After above sub-chronic arsenic exposure, compared with the non-FMT group, fecal arsenic excretion, liver and plasma arsenic accumulation were significantly lower (P < 0.05), and that in kidney, hair, and thighbone present no significant differences. Metabolomics of feces- plasma-brain axis were also disturbed, some up-regulated metabolites in feces, plasma, and cerebral cortex may play positive roles for the host. Therefore, microbial detoxification has potential in the treatment of sub-chronic arsenic poisoning. However, gut flora is an extremely complex community with different microorganisms have different arsenic metabolizing abilities, and various microbial metabolites. Coupled with the matrix effects, these factors will have various effects on the efflux and accumulation of arsenic. The definite effects (detoxification or non-detoxification) could be not assured based on the current study, and more systematic and rigorous studies are needed in the future.

Divergent responses of cropland soil organic carbon to warming across the Sichuan Basin of China.

Cropland soils are considered to have the potential to sequester carbon (C). Warming can increase soil organic C (SOC) by enhancing primary production, but it can also cause carbon release from soils. However, the role of warming in governing cropland SOC dynamics over broad geographic scales remains poorly understood. Using over 4000 soil samples collected in the 1980s and 2010s across the Sichuan Basin of China, this study assessed the warming-induced cropland SOC change and the correlations with precipitation, cropland type and soil type. Results showed mean SOC content increased from 11.10 to 13.85 g C kg-1. Larger SOC increments were observed under drier conditions (precipitation < 1050 mm, dryland and paddy-dryland rotation cropland), which were 1.67-2.23 times higher than under wetter conditions (precipitation > 1050 mm and paddy fields). Despite the significant associations of SOC increment with crop productivity, precipitation, fertilization, cropland type and soil type, warming also acted as one of major contributors to cropland SOC change. The SOC increment changed parabolically with the rise in temperature increase rate under relatively drier conditions, while temperature increase had no impact on cropland SOC increment under wetter conditions. Meanwhile, the patterns of the parabolical relationship varied with soil types in drylands, where the threshold of temperature increase rate, the point at which the SOC increment switched from increasing to decreasing with warming, was lower for clayey soils (Ali-Perudic Argosols) than for sandy soils (Purpli-Udic Cambosols). These results illustrate divergent responses of cropland SOC to warming under different environments, which were contingent on water conditions and soil types. Our findings emphasize the importance of formulating appropriate field water management for sustainable C sequestration and the necessity of incorporating environment-specific mechanisms in Earth system models for better understanding of the soil C-climate feedback in complex environments.

Diabetic bone regeneration with nanoceria-tailored scaffolds by recapitulating cellular microenvironment: Activating integrin/TGF-ß co-signaling of MSCs while relieving oxidative stress.

Regenerating defective bone in patients with diabetes mellitus remains a significant challenge due to high blood glucose level and oxidative stress. Here we aim to tackle this issue by means of a drug- and cell-free scaffolding approach. We found the nanoceria decorated on various types of scaffolds (fibrous or 3D-printed one; named nCe-scaffold) could render a therapeutic surface that can recapitulate the microenvironment: modulating oxidative stress while offering a nanotopological cue to regenerating cells. Mesenchymal stem cells (MSCs) recognized the nanoscale (tens of nm) topology of nCe-scaffolds, presenting highly upregulated curvature-sensing membrane protein, integrin set, and adhesion-related molecules. Osteogenic differentiation and mineralization were further significantly enhanced by the nCe-scaffolds. Of note, the stimulated osteogenic potential was identified to be through integrin-mediated TGF-ß co-signaling activation. Such MSC-regulatory effects were proven in vivo by the accelerated bone formation in rat calvarium defect model. The nCe-scaffolds further exhibited profound enzymatic and catalytic potential, leading to effectively scavenging reactive oxygen species in vivo. When implanted in diabetic calvarium defect, nCe-scaffolds significantly enhanced early bone regeneration. We consider the currently-exploited nCe-scaffolds can be a promising drug- and cell-free therapeutic means to treat defective tissues like bone in diabetic conditions.

Microbial Diversity Analyses of Fertilized Thitarodes Eggs and Soil Provide New Clues About the Occurrence of Chinese Cordyceps.

Chinese cordyceps is a well-known fungus-larva complex with medicinal and economic importance. At present the occurrence of Chinese cordyceps has not been fully illuminated. In this study, the microbial diversities of fertilized Thitarodes eggs from sites A (high occurrence rates of Chinese cordyceps), B (low occurrence rates), and C (no Chinese cordyceps) were analyzed using 16S rRNA and ITS gene-sequencing technique. The previous sequencing data of soil from the same sites were conjointly analyzed. The results showed that bacterial communities among the eggs were significantly different. The bacterial diversity and evenness were much higher on site A. Wolbachia was overwhelmingly predominant in the eggs of sites B and C, while Spiroplasma showed preference on site A. The fungal between-group differences in the eggs were not as significant as that of bacteria. Purpureocillium in Cordyceps-related families showed preference on site A. Wolbachia, Spiroplasma, and Purpureocillium were inferred to be closely related to Chinese cordyceps occurrence. Intra-kingdom and inter-kingdom network analyses suggest that closer correlations of microbial communities (especially closer fungal positive correlations) in fertilized eggs might promote Chinese cordyceps occurrence. Besides, metabolic pathway analysis showed that in fertilized eggs or soil the number of bacterial metabolic pathways with significant differences in every comparison between two sites was greater than that of fungi. Collectively, this study provides novel information about the occurrence of Chinese cordyceps, contributing to the large-scale artificial cultivation of Chinese cordyceps.

In situ analysis of variations of arsenicals, microbiome and transcriptome profiles along murine intestinal tract.

In situ-based studies on microbiome-host interactions after arsenic exposure are few. In this study, the variations in arsenics, microbiota, and host genes along murine intestinal tracts were determined after arsenic exposure for two months. There was a gradual increase in the concentration of total As (CtAs) in feces from ileum to colon, whereas CtAs in the corresponding tissues were relatively stable. Differences in arsenic levels between feces and tissues were significantly different. The proportion of arsenite (iAsⅢ) in feces gradually decreased, however, it gradually increased in tissues. After arsenic exposure, the diversity and abundance of microbial community and networks in each segment were significantly dysregulated. Notably, 328, 579 and 90 differently expressed genes were detected in ileum, cecum, and colon, respectively. In addition, microbiome and transcriptome analyses showed a significant correlation between the abundance of Faecalibaculum and expressions of Plb1, Hspa1b, Areg and Duoxa2 genes. This implies that they may be involved in arsenic biotransformation. In vitro experiments using Biofidobactrium and Lactobacillus showed that probiotics have arsenic transformation abilities. Therefore, gut microbiome may modulate arsenic accumulation, excretion and detoxification along the digestive tract. Moreover, the abundance and diversity of gut microbiome may be related to the changes in host health.

Sub-chronic low-dose arsenic in rice exposure induces gut microbiome perturbations in mice.

Long-term consumption of arsenic-contaminated rice has become a public health issue that urgently needs to be addressed. In this study, mice were exposed to arsenic in rice (low dose, 0.91 mg/kg; medium dose, 9.1 mg/kg) for 30 days and 60 days, respectively, and the effects on pathological structures of spleen and skin, as well as the structure of the fecal microbiome were examined. The findings revealed dose/time cumulative effects on pathological changes, with even a low dose exposure for 30 days causing destruction of splenic follicular structure and thickening of dermal keratinized and epidermal layers. The Firmicutes/Bacteroidetes ratio in the community and the positive/negative ratio in network links were higher in arsenic groups, suggesting that arsenic resulted in a less healthy and unstable microbiome for the host. Thus lifetime consumption of arsenic in rice may have potential health effects on humans and must be carefully assessed to safeguard human health. Furthermore, in arsenic groups, arsenic-resistant bacteria or arsenic hazards remediation bacteria changed to be the dominant bacteria and acted as the core bacteria in the network modules. Some microbial arsenic transforming genes (arsC, arsR, arsA, ACR3, and aoxB) differed, indicating that the gut microbiome changed to withstand arsenic stress. Furthermore, Faecalibaculum, Lachnospiraceae_NK4A136_group, Angelakisella, Ruminiclostridium, and Desulfovibrionaceae are positively associated with arsenic dosage and may be useful in the early detection of arsenicals.

Collective enantioselective total synthesis of (+)-sinensilactam A, (+)-lingzhilactone B and (-)-lingzhiol: divergent reactivity of styrene.

The collective total synthesis of (+)-sinensilactam A, (+)-lingzhilactone B, (+)-lingzhilactone C and (-)-lingzhiol has been accomplished from a common epoxide intermediate 9. Chemoselective epoxy opening with either an aryl or alkene moiety of styrene led to different carbon skeletons, which can be advanced to a divergent and concise total synthesis of four meroterpenoids.

Detection of the Soluble Solid Contents from Fresh Jujubes during Different Maturation Periods Using NIR Hyperspectral Imaging and an Artificial Bee Colony.

To perform accurate and synchronous detection of the soluble solid contents (SSC) in fresh jujubes at different stages of maturity, hyperspectral imaging was used to establish robust models. The combined data constituting four maturation stages were used to build the grid-search least squares support vector machine (GS-LS-SVM) model. The determination coefficient (Rp2), the root-mean-square error (RMSEP), and the residual predictive deviation (RPD) of the prediction set for samples of the overall stages were 0.98, 1.10%, and 7.85, respectively. Furthermore, a successive projections algorithm (SPA) was used to extract the characteristic wavelengths of the combined data. An artificial bee colony (ABC) algorithm (for the prediction set, Rp2 = 0.98, RMSEP = 1.19%, RPD = 7.25) was used to improve the SPA-LS-SVM model, which was better than the SPA-GS-LS-SVM model (for the prediction set, Rp2 = 0.98, RMSEP = 1.24%, RPD = 6.96). Lastly, visualization of the SSC distribution map was performed based on the SPA-ABC-LS-SVM model, which clearly showed that the SSC gradually increased during maturation. The results indicated that it was realistic to construct a detection model of the multimaturity stage. This research also demonstrated that the combination of hyperspectral imaging and the ABC had good application values in the testing of agricultural products.

Synthesis of trisaccharide repeating unit of fucosylated chondroitin sulfate.

We described the chemical synthesis of a sulfated trisaccharide repeating unit of fucosylated chondroitin sulfate (FCS), which has significant anticoagulant activity. Well-functionalized monosaccharides were readily prepared, and highly efficient glycosylations using a common activator (NIS/TfOH) were also presented. The synthesized trisaccharide 4 could be used to extend oligosaccharide sequences.

Synthesis and Cytotoxicities of Royleanone Derivatives.

Carnosic acid was used as starting material to synthesize royleanone derivatives featured C11-C14 para quinone. The importance of C-20 group of royleanone derivatives was verified by the cytotoxicity assay of royleanonic acid, miltionone I and deoxyneocrptotanshinone. Following our synthetic route, 15 amide derivatives were synthesized and 8 compounds exhibited moderate cytotoxic activities against three human cancer lines in vitro.