Roxithromycin regulates intestinal microbiota and alters colonic epithelial gene expression

Intergenerational and biological effects of roxithromycin and polystyrene microplastics to Daphnia magna

The influence of microplastics (MPs) on transgenerational effects of pharmaceuticals are drawing growing attention, however, whether aged process will alter the carrier effects of MPs were unknown. In this study, the intergenerational toxicity of single and combined exposure of polystyrene microplastics (PS-MPs) and roxithromycin (ROX) were investigated at the environmentally related concentrations, using Daphina magna as test organism. In the presence of UV-aged PS-MPs, the survival of D. magna for maternal generation (F0) at ROX concentration of 0.1 and 10 µg/L were increased by 20% and 40%, respectively. Meanwhile, the inhibition effects of ROX on the number of offspring and intrinsic rate of natural increase were obviously moderated. All these reproductive toxicity of ROX and PS-MPs in the first offspring (F1) were further aggravated both for the single and combined exposure. And the adverse effects disappeared much easier for the single exposure compared to the co-exposure through subsequent recovery. The combined exposure resulted in the change of inhibition of ROX on the swimming velocity and acceleration of D. magna into induction, while the feeding behavior kept inhibited. The AChE activity was distinctly increased by 1.61-3.25 times for the single and combined treatments, and the induction level of UV-aged MPs was higher than that of original MPs. Oxidative stress of the single exposure of ROX and original PS-MPs was observed with obvious induction of T-AOC and SOD activity, while the significant increase of MDA content was observed for the co-exposure. Among all indicators, the biochemical biomarkers and time of first brood were attributed to a class among all indicators, indicating that the time of first brood might be the most sensitive reproductive toxicity index. These results illustrated that both maternal impacts and offspring quality need to be considered for assessment of interaction of emerging contaminants.

Metagenomic analysis explores the interaction of aged microplastics and roxithromycin on gut microbiota and antibiotic resistance genes of Carassius auratus

The aging process changes the physicochemical structure of microplastics and affects environmental behaviors and toxicological effects of coexisting pollutants, thereby posing ecological risks. In this study, the effects of aged polystyrene microplastics alone or in combination with the 100 μg/L roxithromycin (ROX) on intestines of Carassius auratus were investigated. The carrier effect of microplastics was enhanced by aging due to changes in functional groups and surface area, which led to an increase in the bioaccumulation of ROX. The combined exposure of aged microplastics (APS) and ROX caused more inflammatory cell infiltration and cilia defects, and significantly inhibited the activity of amylase and lipase. Metagenomic sequencing revealed that the combined exposure of microplastics and ROX increased the abundance of Gemmobacter, Bosea, Rhizobium, and Shinella and decreased the abundance of Cetobacterium and Akkermansia (p < 0.05). The presence of APS enhanced the selective enrichment of antibiotic resistance genes. What's more, the influence of microplastics and antibiotics on gut microbiota was closely related to carbohydrate metabolism and amino acid metabolism activities, as well as the abundance of baca and sul1 resistance genes. These results expand our understanding of the interaction mechanism between APS and antibiotics in real aquatic environment.

Elucidating the Relations between Gut Bacterial Composition and the Plasma and Fecal Metabolomes of Antibiotic Treated Wistar Rats

The gut microbiome is vital to the health and development of an organism, specifically in determining the host response to a chemical (drug) administration. To understand this, we investigated the effects of six antibiotic (AB) treatments (Streptomycin sulfate, Roxithromycin, Sparfloxacin, Vancomycin, Clindamycin and Lincomycin hydrochloride) and diet restriction (–20%) on the gut microbiota in 28-day oral toxicity studies on Wistar rats. The fecal microbiota was determined using 16S rDNA marker gene sequencing. AB-class specific alterations were observed in the bacterial composition, whereas restriction in diet caused no observable difference. These changes associated well with the changes in the LC–MS/MS- and GC–MS-based metabolome profiles, particularly of feces and to a lesser extent of plasma. Particularly strong and AB-specific metabolic alterations were observed for bile acids in both plasma and feces matrices. Although AB-group-specific plasma metabolome changes were observed, weaker associations between fecal and plasma metabolome suggest a profound barrier between them. Numerous correlations between the bacterial families and the fecal metabolites were established, providing a holistic overview of the gut microbial functionality. Strong correlations were observed between microbiota and bile acids, lipids and fatty acids, amino acids and related metabolites. These microbiome–metabolome correlations promote understanding of the functionality of the microbiome for its host.

Ribosome-targeting antibacterial agents: Advances, challenges, and opportunities

Ribosomes, which synthesize proteins, are critical organelles for the survival and growth of bacteria. About 60% of approved antibiotics discovered so far combat pathogenic bacteria by targeting ribosomes. However, several issues, such as drug resistance and toxicity, have impeded the clinical use of ribosome-targeting antibiotics. Moreover, the complexity of the bacteria ribosome structure has retarded the discovery of new ribosome-targeting agents that are considered as the key to the drug-resistance and toxicity. To deal with these challenges, efforts such as medicinal chemistry optimization, combination treatment, and new drug delivery system have been developed. But not enough, the development of structural biology and new screening methods bring powerful tools, such as cryo-electron microscopy technology, advanced computer-aided drug design, and cell-free in vitro transcription/translation systems, for the discovery of novel ribosome-targeting antibiotics. Thus, in this paper, we overview the research on different aspects of bacterial ribosomes, especially focus on discussing the challenges in the discovery of ribosome-targeting antibacterial drugs and advances made to address issues such as drug-resistance and selectivity, which, we believe, provide perspectives for the discovery of novel antibiotics.

Pectin and inulin stimulated the mucus formation at a similar level: An omics-based comparative analysis

Mucin 2 (MUC2) is the skeleton of colonic mucus that comprises the physical intestinal barrier. Different dietary polysaccharides may affect colonic mucus at different extents. The effect of pectin on MUC2 production is contradictory. To investigate whether and how pectin affected hosts' colonic mucus, the amount of MUC2 in colon, the cecal, mucosal microbiota, and metabolites profiles were analyzed and compared with inulin. The results showed pectin stimulated the production of MUC2 at a similar level to inulin. Both interventions increased the abundance of cecal Lachnospira and Christensenellaceae_R-7_group, and enhanced the production of specific metabolites including soyasapogenol B 24-O-b-d-glucoside, lucyoside Q, trans-EKODE-(E)-Ib, and 1,26-dicaffeoylhexacosanediol. Additionally, pectin increased the relative abundance (RA) of cecal Lactobacillus, and induced less RA of potentially harmful bacteria such as Helicobacter in mucosal microbiota than inulin. In conclusion, we first reported that pectin and inulin stimulated the mucus formation at a similar level. Two genera of cecal bacteria and four metabolites may play an important role in enhancing the production of MUC2. Moreover, the MUC2 production may be unrelated to several traditional health-beneficial bacteria; pectin possibly performed as good as or better than the inulin in rats' gut.

Morpho-physiological and transcriptome analysis provide insights into the effects of zinc application on nitrogen accumulation and metabolism in wheat (Triticum aestivum L.)

Nitrogen (N) is the essential nutrient for wheat growth and development, its accumulation and metabolism controlled by many other elements. Zinc (Zn) is one of the important elements which tends to have effects on plant N homeostasis. Here in our study, 0 μM and 5 μM Zn was applied to the wheat seedlings culturing in 5 mM (+N) and 0.5 mM (-N) N treatments, respectively. The results showed that the shoot and root length growth performance, total N, NO₃^-, and amino acid concentrations, glutamine synthetase (GS) activity of wheat were facilitated by 5 μM Zn application under + N and -N conditions. Quantitative real-time PCR (qRT-PCR) analysis indicated that several NO₃^- transporters genes (TaNRT2.1, TaNPF7.1 and TaNPF7.2) and the genes encoding GS (TaGS1 and TaGS2) were induced by 5 μM Zn. In addition, transcriptional changes in wheat shoots and roots with Zn application were tested by RNA-seq techniques. A total of 147/551 induced and 36/2162 reduced differentially expression genes (DEGs) was detected in wheat shoots/roots, respectively. GO and KEGG enrichment analyses showed that 5 μM Zn mainly affected the glutathione (GSH) metabolism, phenylpropanoid biosynthesis and amino acid metabolism, involving in N homeostasis. Furthermore, the relative expression of genes related to phenylalanine, cysteine and methionine metabolism was induced by 5 μM Zn to promote the amino acid accumulation. Overall, these results highlight the facilitating of N accumulation by low level Zn, and provide an insight into the effects of Zn on N metabolism in wheat.