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Streptococcus mutans (S. mutans) is one of the major etiological agents of dental caries. Interfering with the expression of genes associated with cariogenicity of S. mutans is an effective ecological approach for caries prevention. Thus, understanding the role of genes related to cariogenicity in S. mutans is important. dltD is a conserved gene in Gram-positive bacteria, which is involved in D-alanylation of lipoteichoic acid to modify cell surface charge. In vivo caries experiments have shown significant decreases in the caries severity in rats infected with S. mutans dltD-deficient strain. Although the impact of dltD on bacterial surface charge and division in other Gram-positive bacteria is known, its role in S. mutans biological functions remains unclear. This study aimed to investigate the biological functions of dltD in S. mutans. We examined growth curves, morphology, autolysis, biofilm formation, and cell membrane properties of S. mutans wild strain and dltD-deficient strain. Our results revealed that dltD plays a key role in the growth and autolysis of S. mutans. dltD deletion increased biofilm autolysis, thereby reducing the number of viable bacteria within the biofilm. Furthermore, dltD may have an epistatic effect on cell division and surface charge. Its regulatory network needs to be further elucidated. This study shed light on therole of dltD in the growth of S. mutans, thereby enhancing our understanding of its function.

ABSTRACTThe gut microbiota (GM) and its metabolites affect the host nervous system and are involved in the pathogeneses of various neurological diseases. However, the specific GM alterations under pathogenetic pressure and their contributions to the “microbiota – metabolite – brain axis” in Alzheimer’s disease (AD) remain unclear. Here, we investigated the GM and the fecal, serum, cortical metabolomes in APP/PS1 and wild-type (WT) mice, revealing distinct hub bacteria in AD mice within scale-free GM networks shared by both groups. Moreover, we identified diverse peripheral – central metabolic landscapes between AD and WT mice that featured bile acids (e.g. deoxycholic and isodeoxycholic acid) and unsaturated fatty acids (e.g. 11Z-eicosenoic and palmitoleic acid). Machine-learning models revealed the relationships between the differential/hub bacteria and these metabolic signatures from the periphery to the brain. Notably, AD-enriched Dubosiella affected AD occurrence via cortical palmitoleic acid and vice versa. Considering the transgenic background of the AD mice, we propose that Dubosiella enrichment impedes AD progression via the synthesis of palmitoleic acid, which has protective properties against inflammation and metabolic disorders. We identified another association involving fecal deoxycholic acid-mediated interactions between the AD hub bacteria Erysipelatoclostridium and AD occurrence, which was corroborated by the correlation between deoxycholate levels and cognitive scores in humans. Overall, this study elucidated the GM network alterations, contributions of the GM to peripheral – central metabolic landscapes, and mediatory roles of metabolites between the GM and AD occurrence, thus revealing the critical roles of bacteria in AD pathogenesis and gut – brain communications under pathogenetic pressure.

ABSTRACTMelatonin has various physiological effects, such as the maintenance of circadian rhythms, anti-inflammatory functions, and regulation of intestinal barriers. The regulatory functions of melatonin in gut microbiota remodeling have also been well clarified; however, the role of gut microbiota in regulating host melatonin production remains poorly understood. To address this, we studied the contribution of gut microbiota to host melatonin production using gut microbiota-perturbed models. We demonstrated that antibiotic-treated and germ-free mice possessed diminished melatonin levels in the serum and elevated melatonin levels in the colon. The influence of the intestinal microbiota on host melatonin production was further confirmed by fecal microbiota transplantation. Notably, Lactobacillus reuteri (L. R) and Escherichia coli (E. coli) recapitulated the effects of gut microbiota on host melatonin production. Mechanistically, L. R and E. coli activated the TLR2/4/MyD88/NF-κB signaling pathway to promote expression of arylalkylamine N-acetyltransferase (AANAT, a rate-limiting enzyme for melatonin production), and MyD88 deficiency in colonic epithelial cells abolished the influence of intestinal microbiota on colonic melatonin production. Collectively, we revealed a specific underlying mechanism of gut microbiota to modulate host melatonin production, which might provide novel therapeutic ideas for melatonin-related diseases.

A landslide inventory is essential for numerous applications, including disaster prevention and mitigation. The emergence of advanced satellite technologies and the proliferation of extensive satellite imagery have greatly enhanced the role of deep learning-based semantic segmentation networks in the development of comprehensive landslide inventories. In deep learning, especially in semantic segmentation tasks, the loss function is crucial to guide the training of neural networks. However, typical loss functions have several challenges and shortcomings, including difficulty in handling objects of different scales and neglecting spatial correlation. These drawbacks hinder semantic segmentation networks from solely concentrating on accurately predicting landslide categories with rich semantic information. The spatial details (e.g. small landslides and precise landslide boundary information) in the segmentation results may be lost, reducing the accuracy of landslide extraction. Most studies only focus on training and detection in the local region. Consequently, detecting new unexplored region and detrimental to emergency response is challenging. This study presents a level set loss-guided semantic segmentation network, which can be integrated with different semantic segmentation networks, to address these issues. Three out of five study areas (e.g. Bijie, Jiuzhaigou, and Taitung) are used for model training and accuracy evaluation, while the rest, which are newly unexplored regions (e.g. Hokkaido and Haiti), are used to test the transferability of the proposed loss function in different regions. The study results validate the effectiveness of the designed level set loss in various semantic segmentation networks and in different study areas for landslide extraction.

AbstractRock mass strength parameters are critical when applying the permanent-displacement analysis to landslide susceptibility assessment. Previous studies use limited measured data to assign a constant value for each lithology. Since the rock mass strength is spatially heterogeneous, assigning a constant value to each lithology cannot effectively reflect the spatial heterogeneity of rock mass strength, reducing the reliability of seismic landslide susceptibility assessment. Here we present an analysis of a well-documented seismic landslide inventory and the lithological environment, and develop an empirical model to quantify the rock mass strength heterogeneity. The rock mass strength heterogeneity was subsequently taken as an input of the permanent-displacement analysis to assessing regional seismic landslide susceptibility. Results on two case studies show that considering the rock mass strength heterogeneity would significantly improve seismic landslide susceptibility assessment. The findings of this study are valuable for earthquake emergency rescue and post-earthquake land plans.

AbstractDeep gob-side entry (DGSE) shows rock burst risk under the condition of kilometer depth and hard roof. Based on the established conditions of the Tengdong coal mine, theoretical analysis, microseismic (MS) monitoring, and numerical modeling were used to study the rock burst mechanism of DGSE. Results show that MS events mainly occurred on the solid side of DGSE and the intense dynamic load was mainly caused by the breaking of low hard roof strata, which can release 2.64 × 105 J elastic energy per meter. The surrounding stress of DGSE was asymmetrical due to the coal pillar yielding and hanging roof’s weight, and the load of coal pillar is negatively correlated with that of solid. Simulation shows the vertical stress evolution of coal pillar and solid shows significant diversity. Coal pillar’s vertical stress first drops sharply, and then increases gradually, finally stable at 10.6 MPa with the DGSE’s excavation. Contrarily, solid’s vertical stress gradually rises and was finally stable at 40.9 MPa. Under roof dynamic loading, the vibration velocity of the entry’s top was higher than that of the floor which was caused by the increase of the propagation distance and the reflection and diffraction effect of waves. The vibration velocity of the coal pillar was significantly higher than that of the solid which is because higher stress can lead to faster attenuation of vibration velocity. After dynamic loading, the coal pillar’s principal stress and principal stress difference decreased while that of the solid can be divided into two drop areas and one rising area. Periodic pressure relief that was carried out in the rising area can reduce the rock burst risk on the solid side of DGSE.

Object detection, which is one of the most fundamental visual recognition tasks, has been a hotspot in computer vision. CNN (Convolutional Neural Networks) have been widely employed for building detector. Due to the success of RPN (Region Proposal Network), the two-stage detectors get both classification accuracy and precise regression bounding boxes. However, they still struggle in small-size object detection. In this paper, we present a deep network, namely Spatial Fine-Grained Network (SFGN). The SFGN that exploits Spatial Fine-Grained Features (SFGF) concatenates the higher resolution features, which is fine-grained with the low resolution features and high-level semantic by stacking spatial features for fine-grained features. An enhanced region proposal generator is proposed to get the objectless for small object to obtain a small set of proposal. The contextual information surrounding the region of interest is embedded using local spatial information for increasing the useful information and discriminating the background. For improving the detection performance, we use a simple yet surprisingly effective online hard example mining (OHEM) algorithm for training region proposal generator. It embeds an efficiently implemented soft non-maximum suppression (soft-NMS) for replacing with tradition NMS to obtain consistent improvements without increasing the computational complexity in inference. On PASCAL VOC 2007 and PASCAL VOC 2012 datasets, our SFGN improves baseline model from 81.2% mAP to 80.6% mAP. On MS COCO dataset, SFGN also performs better than baseline model. As intuition suggests, our detection results provide strong evidence that our SFGN improves detection accuracy, especially in small object test.

Bariatric surgery (BS) is a dependable method for managing obesity and metabolic diseases, however, the regulatory processes of lipid metabolism are still not well elucidated. Differentially expressed genes (DEGs) were analysed through three transcriptomic datasets of GSE29409, GSE59034 and GSE72158 from the GEO database regarding subcutaneous adipose tissue (SAT) after BS, and 37 DEGs were identified. The weighted gene co-expression network analysis (WGCNA), last absolute shrinkage and selection operator (LASSO) logistic regression and support vector machine-recursive feature elimination (SVM-RFE) algorithms further screened four key genes involved in the regulation of STMN2, SFRP4, APOE and MXRA5. The GSE53376 dataset was used to further confirm the differential expression of SFRP4, APOE and MXRA5 in the postoperative period. GSEA analysis reveals activation of immune-related regulatory pathways after surgery. Finally, the silencing of MXRA5 was found by experimental methods to affect the expression of PPARγ and CEBPα during the differentiation of preadipocytes, as well as to affect the formation of lipid droplets. In conclusion, SAT immunoregulation was mobilized after BS, while MXRA5 was involved in the regulation of lipid metabolism.

In our previous reports, an endophytic bacterium, Bacillus cereus KP120 was isolated from the halophyte species Kosteletzkya virginica. In this study, the effect of KP120 colonization on Arabidopsis thaliana seedlings was investigated. Our results showed that inoculation with KP120 could promote the growth of A. thaliana seedlings plants under salt-stress conditions, compared with uninoculated controls. After salt treatment, chlorophyll, proline, the activity of antioxidant enzymes, Indole-3-acetic acid and 1-aminocyclopropane-1-carboxylate-deaminase in plants inoculated were increased significantly but malondialdehyde content was decreased compared with the plants under salt stress lonely. Similarly, under non-salt stress, physiological indices above except for MDA in plants inoculated with KP120 were increased compared with control. B. cereus also induced the up-regulation of key genes involved in IAA biosynthesis, responses, transport, down-regulated expression of genes related with ethylene synthesis and response. Our work principally demonstrates that Bacillus cereus KP120 significantly enhances plant growth and increases plant tolerance to salt stress.

The fixed scroll of the scroll compressor is usually immovable, and the deformation of the scrolls may lead to the operation stuck, which may be avoided by designing the fixed scroll as floating one. However, the introduction of floating fixed scroll will inevitably cause the variation of the dynamic characteristics, so it is necessary to establish a simulation model to explore the influence of floating fixed scroll. In this study, a tribo-dynamics model considering floating fixed scroll is established, which couples the key friction pairs composed of fixed scroll, orbiting scroll and frame to reveal the influence of floating scroll on tribological and dynamics performance. The variation of the lubricant viscosity and boundary pressure as well as the deformation of components are included in the model to consider the real working conditions. The results show that compared with the fixed scheme, the floating scheme provides a compensation space for the components deformation, which is conducive to the operation stability; The floating scheme can not only ensure the sealing of the compression chamber, but also reduce the friction work by 53% compared with the fixed clearance of 4µm.

AbstractPrevious studies show that 1-aminocyclopropane-1-carboxylate (ACC) deaminase can facilitate the growth and stress tolerance of hosts by reducing ethylene levels. In this study, the acdS gene encoding ACC deaminase from Bacillus cereus (HK012) was cloned and transformed into tobacco (Nicotiana tabacum L.) by the leaf disc method using Agrobacterium. Molecular detection and physiological analysis of the transgenic tobacco plants were performed. Our results showed the acdS gene was integrated into the tobacco genome and fluorescence microscopy showed that the fusion protein was located on the cell membrane of tobacco root. Compared with control, the transgenic plants showed increases in plant height, root length, dry weight, fresh weight and chlorophyll content; and significant increases in the concentration of proline of 55.15% and 42.7% under salt stress conditions (150 mmol L−1 and 300 mmol L−1 NaCl, respectively). The superoxide dismutase, peroxidase, catalase and ACC deaminase activities of transgenic tobacco were higher than those of control tobacco at 150 and 300 mmol L−1 salt concentrations. Transgenic tobacco seedlings expressing the acdS gene of B. cereus HK012 showed higher salt tolerance than the control plants. The obtained results suggest that the acdS gene of B. cereus can be used to promote salt tolerance in glycophytes by using biotechnology strategies.

The CCCH(C3H) transcription factor is an important transcription factor in plants in the process of plant development, hormone regulation and under stress. Rose is one of the most important commercial flower crops worldwide. However, there are few reports about the C3H gene of rose and Rosa chinensis Jacq. The reference genome sequence becomes a valuable source of data for the C3H genes in rose (RcC3Hs). We identified 31 encoding members in total, which were distributed on seven chromosomes and clustered into 11 subgroups in R. chinensis. Each subgroup has similar group-specific features including motifs, gene structure, cis-acting elements and collinearity in R. chinensis and two other species (Arabidopsis thaliana and Oryza sativa L). The RcC3Hs’tissue-specific expression by quantitative real-time PCR (qRT-PCR) showed that the expression of RcC3Hs was higher in roots and leaves compared with other tissues. These results provide a theoretical basis for the follow-up exploration of the functions of RcC3Hs and the molecular breeding of rose. Supplemental data for this article is available online at https://doi.org/10.1080/13102818.2021.1901609 .

This study aimed to assess oxidative stress and microbiota in pigs at different stocking densities. Markers for oxidative stress were investigated and gut bacteria identified. The pigs were randomly assigned to high-, medium- or low-density groups. The results showed that the superoxide dismutase (SOD) levels in the high- and low-density groups were lower than in the medium-density group. Glutathione peroxidase (GSH-Px) activity was significantly lower in the low-density group and highest in the medium-density group. We found no discrepancies between estimators of bacterial richness across the three groups. The jejunum and ileum were mainly occupied by Firmicutes and Proteobacteria of the classes Bacilli, Clostridia, Erysipelotrichia and Gammaproteobacteria. The ceacum was mainly occupied by Bacteroidetes and Firmicutes of the classes Bacteroidetes, Clostridia and Negativicutes. The results revealed that gut flora was not affected by stocking density. However, stocking density may influence oxidative stress.

Rheumatoid arthritis (RA), a disease that causes joint destruction and bone erosion, is related to osteoclast activity. RA is generally treated with methotrexate (MTX). In this study, a MTX–Alendronate (ALN) conjugate was synthesized and characterized. The conjugate dramatically inhibited osteoclast formation and bone resorption compared with MTX and ALN used alone or in combination. Due to the characteristics of ALN, the MTX–ALN conjugate can adhere to the exposed bone surface and enhance drug accumulation in the pathological region for targeted therapy against osteoclastogenesis. Additionally, MTX was rapidly released in the presence of lysozyme under mildly acidic conditions, similar to inflammatory tissue and osteoclast-surviving conditions, which contributes to inflammatory inhibition; this was confirmed by the presence of pro-inflammatory cytokines. Our study highlights the use of the MTX–ALN conjugate as a potential therapeutic approach for RA by targeting osteoclastogenesis.

Here we isolated and characterized the complete mitochondrial genome of the hybrid grouper (Cromileptes altivelis♀ × Epinephelus tukula♂). It is 16,503 bp long and contains 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and a control region. The nucleotide composition is 29.08% of A, 29.03% of C, 15.66% of G and 26.23% of T, with 55.31% A + T. The phylogenetic analysis by neighbor-joining (NJ) method reveals that the hybrid offspring has a closer relationship to C. altivelis.

Camellia sinensis var. sinensis cultivar Tieguanyin (TGY) is an important Oolong tea variety in China. In this study, we reported a complete chloroplast (cp) genome based on the Illumina sequencing technology and combined de novo and reference-guided assembly strategies. The complete cp genome of ‘TGY’ displayed the regular quadripartite structure: a total of 157,126 bp in length, comprising a large single-copy (LSC, 86,904 bp) region, a small single-copy (SSC, 18,532 bp) region, and a pair of inverted repeats (IRs, 26,095 bp) regions. A lot of 132 predicted genes, including 87 protein-coding genes, 37 tRNA genes, and eight rRNA genes. The overall GC content is 37.3%. Maximum likelihood (ML) phylogenetic tree involving 18 cp genomes of the Camellia genus revealed a relatively independent event of local domestication among three types of cultivars. The complete cp genome of ‘TGY’ provides an insight into tea plants for further understanding evolutionary research on tea plants.

Treatment of ovarian cancer (OC) remains the biggest challenge among gynecological malignancies. Immune checkpoint blockade therapy is promising in many cancers but shows low response rates in OC because of its heterogeneity. Although the biological and molecular heterogeneity of OC has been extensively investigated, heterogeneity of immune microenvironment remains elusive. We have collected the expression profiles of 3071 OC patients from 22 publicly available datasets. CIBERSORT was applied to infer the infiltration fraction of 22 immune cells among 2086 patients with CIBERSORT P

Two novel two-step thermomechanical routes were developed to produce ultrafine-grained ferrite microstructures in a 10Ni–0.1C steel without high-strain deformation. Homogeneous ultrafine ferrite (UFF) structures having mean grain sizes down to 460 nm were fabricated by a total equivalent strain of 0.92 and exhibited high yield strength of 820 MPa with large uniform elongation of 10% and total elongation of 29%. The formation of UFF was attributed to two different phenomena, i.e. dynamic transformation from austenite to ferrite and dynamic recrystallization of ferrite.

The complete mitochondrial genome of hybrid grouper from Epinephelus awoara (♀) ×E. tukula (♂) was obtained by PCR amplification. The circular genome was 16,801 bp in length, consisting of 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and a control region (D-loop region). The overall base composition was as follows: A: 28.46%, T: 27.27%, C: 27.27%, G: 16.49%. The new results may provide valuable data for the genetic and taxonomic research on artificial hybrid grouper.