Antibiotic-Induced Gut Microbiota Dysbiosis Modulates Host Transcriptome and m6A Epitranscriptome via Bile Acid Metabolism.

Gut microbiota can influence host gene expression and physiology through metabolites. Besides, the presence or absence of gut microbiome can reprogram host transcriptome and epitranscriptome as represented by N6-methyladenosine (m6A), the most abundant mammalian mRNA modification. However, which and how gut microbiota-derived metabolites reprogram host transcriptome and m6A epitranscriptome remain poorly understood. Here, investigation is conducted into how gut microbiota-derived metabolites impact host transcriptome and m6A epitranscriptome using multiple mouse models and multi-omics approaches. Various antibiotics-induced dysbiotic mice are established, followed by fecal microbiota transplantation (FMT) into germ-free mice, and the results show that bile acid metabolism is significantly altered along with the abundance change in bile acid-producing microbiota. Unbalanced gut microbiota and bile acids drastically change the host transcriptome and the m6A epitranscriptome in multiple tissues. Mechanistically, the expression of m6A writer proteins is regulated in animals treated with antibiotics and in cultured cells treated with bile acids, indicating a direct link between bile acid metabolism and m6A biology. Collectively, these results demonstrate that antibiotic-induced gut dysbiosis regulates the landscape of host transcriptome and m6A epitranscriptome via bile acid metabolism pathway. This work provides novel insights into the interplay between microbial metabolites and host gene expression.

Transcriptome-wide analysis of mRNA N6 -methyladenosine modification in the embryonic development of Spodoptera frugiperda.

N6 -methyladenosine (m6 A) RNA is the most abundant modification of mRNA, and has been demonstrated in regulating various post-transcriptional processes. Many studies have shown that m6 A methylation plays key roles in sex determination, neuronal functions, and embryonic development in Drosophila and mammals. Here, we analyzed transcriptome-wide profile of m6 A modification in the embryonic development of the destructive agricultural pest Spodoptera frugiperda. We found that the 2 key mRNA m6 A methyltransferases SfrMETTL3 and SfrMETTL14 have high homologies with other insects and mammals, suggesting that SfrMETTL3 and SfrMETTL14 may have conserved function among different species. From methylated RNA immunoprecipitation sequencing analysis, we obtained 46 869 m6 A peaks representing 8 587 transcripts in the 2-h embryos after oviposition, and 41 389 m6 A peaks representing 9 230 transcripts in the 24-h embryos. In addition, 5 995 m6 A peaks were differentially expressed including 3 752 upregulated and 2243 downregulated peaks. Functional analysis with Gene Ontology and Kyoto Encyclopedia of Genes and Genomes suggested that differentially expressed m6 A peak-modified genes were enriched in cell and organ development between the 2- and 24-h embryos. By conjoint analysis of methylated RNA immunoprecipitation-seq and RNA-seq data, we found that RNA m6 A methylation may regulate the transcriptional levels of genes related to tissue and organ development from 2- to 24-h embryos. Our study reveals the role of RNA m6 A epigenetic regulation in the embryonic development of S. frugiperda, and provides new insights for the embryonic development of insects.

Gut Microbiota Dysbiosis Influences Metabolic Homeostasis in Spodoptera frugiperda.

Insect gut microbiota plays important roles in acquiring nutrition, preventing pathogens infection, modulating immune responses, and communicating with environment. Gut microbiota can be affected by external factors such as foods and antibiotics. Spodoptera frugiperda (Lepidoptera: Noctuidae) is an important destructive pest of grain crops worldwide. The function of gut microbiota in S. frugiperda remains to be investigated. In this study, we fed S. frugiperda larvae with artificial diet with antibiotic mixture (penicillin, gentamicin, rifampicin, and streptomycin) to perturb gut microbiota, and then examined the effect of gut microbiota dysbiosis on S. frugiperda gene expression by RNA sequencing. Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria were the most dominant phyla in S. frugiperda. We found that the composition and diversity of gut bacterial community were changed in S. frugiperda after antibiotics treatment. Firmicutes was decreased, and abundance of Enterococcus and Weissella genera was dramatically reduced. Transcriptome analysis showed that 1,394 differentially expressed transcripts (DETs) were found between the control and antibiotics-treated group. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) results showed that antibiotics-induced dysbiosis affected many biological processes, such as energy production, metabolism, and the autophagy-lysosome signal pathway. Our results indicated that dysbiosis of gut microbiota by antibiotics exposure affects energy and metabolic homeostasis in S. frugiperda, which help better understand the role of gut microbiota in insects.

Flexural Properties of Renewable Coir Fiber Reinforced Magnesium Phosphate Cement, Considering Fiber Length.

Coir fiber (CF), a renewable natural plant fiber, is more competitive in improving poor toughness and crack resistance of magnesium phosphate cement (MPC) than artificial fibers, due to its slight energy consumptions and low costs in production and waste treatment. In this paper, a typical three-point bending test was carried out to study the effects of CF length on MPC flexural properties. A total of forty-two cuboid specimens were employed to investigate the flexural strength, load-deflection behavior, and flexural toughness of MPC, with CF lengths varying from 0 to 30 mm at the curing age of 7 days and 28 days. Results showed that, at both two curing ages, MPC flexural strength first increased with CF length increasing, and then deceased when CF length exceeded the threshold. However, with the increase of CF length, MPC flexural toughness increased continuously, while MPC elastic modulus displayed a decreasing trend. Additionally, Modern micro testing techniques, such as scanning electron microscope (SEM) and X-ray diffraction (XRD), were also used to study the microstructure and phase compositions of specimens for further explaining the themicroscopic mechanism.

Study on the Compressive Properties of Magnesium Phosphate Cement Mixing with Eco-Friendly Coir Fiber Considering Fiber Length.

Coir fiber (CF), an eco-friendly and renewable natural fiber, was introduced into magnesium phosphate cement (MPC) mortar to improve its crack resistance. A total of 21 specimens were employed to investigate the failure pattern, compressive strength, stress-strain curve, and energy absorption of MPC with varying CF lengths (0, 5, 10, 15, 20, 25, and 30 mm) after a curing period of 28 days through a static compressive test. The results demonstrated that compressive strength, elastic modulus, and secant modulus decreased with the increase in CF length. However, energy absorption presented a convex curve, which increased to the maximum value (77.0% relative to the value of the specimen without CF) with a CF length of 20 mm and then declined. A series of modern micro-tests were then carried out to analyze the microstructure and composition of specimens to explain the properties microscopically.