Abstract Food-grade carrageenan (CGN) is widely used as a food additive, but its potential health risks remain controversial. This study investigated the effects of dietary food-grade kappa-CGN (κ-CGN) on liver health in mice. Our findings demonstrated that dietary κ-CGN induced liver inflammation, oxidative stress, and fibrosis. Metabolomic analyses identified elevated circulatory bile acids as a potential contributor to κ-CGN-induced liver injury. 16S rRNA sequencing revealed gut microbiota dysbiosis accompanied by increased proinflammatory cytokine production and altered fecal bile acid profiles. These disruptions dysregulated bile acid metabolism via the intestinal FXR/FGF15 signaling pathway, potentially resulting in the liver injury. Altered short-chain fatty acid profiles were also observed, representing an additional metabolic consequence of dysbiosis induced by κ-CGN. These results highlight the intricate interplay between gut microbiota, bile acid metabolism, and liver health, offering new insights into the metabolic risks associated with dietary exposure of food-grade κ-CGN.
Abstract Phthalate esters (PAEs) contaminate agricultural soils, yet how introduced endophytes reshape rhizosphere processes and influence PAE dissipation remains unclear. We investigated the PAE-degrading endophyte Bacillus megaterium YJB3 in choysum (Brassica parachinensis L.) grown in soils spiked with dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP). YJB3 alleviated PAE-induced inhibition of lateral-root development and enhanced PAE dissipation, particularly DEHP dissipation under low contamination. Soil zymography revealed YJB3-associated shifts in the spatial distributions of β-glucosidase and xylanase activities around roots, with an increased proportion of β-glucosidase hotspots within the total enzyme-active area under PAE stress. Across the rhizosphere, rhizoplane, and endosphere, YJB3 inoculation was associated with changes in bacterial community composition and higher relative abundances of several genera, including Streptomyces, Nocardioides, and Kitasatospora. Collectively, YJB3-associated enhancement of PAE dissipation coincided with changes in root development, rhizosphere enzyme activities, and root-associated bacterial communities, highlighting the potential of endophytes for remediation of PAE-contaminated soils.
Abstract The 11α-hydroxylation of steroids is essential for their semisynthesis. However, natural 11α-hydroxylases are scarce and generally exhibit low catalytic activity. In this study, a structure–function-guided computational approach was applied to identify a cytochrome P450 monooxygenase (CosaP450) with 11α-hydroxylation activity. By modulating the flexibility of the gating helix (N62-E75), the engineered variant MT3 (T72Q/F70T/Y226Q) increased the production of 11α,17α-hydroxyprogesterone (11α,17α-OHP) from 680 mg/L to 1140 mg/L. Then, the targeted engineering of the substrate channel and active site was employed based on the multiscale MD simulations, and the mutant MT6 (T72Q/F70T/Y226Q/V374A/G137T/E118G) achieved a yield of 1863 mg/L. MD analysis revealed that V374A relieved channel steric hindrance, while G137T/E118G remodeled the hydrogen-bond network to stabilize the binding conformation. Redox partner engineering further enhanced the titer of MT6 AnCPR to 2489 mg/L. This work establishes a computational framework for rational discovery and engineering of efficient 11α-hydroxylases, providing a promising strategy for enzymatic steroid functionalization.
Abstract Mastitis causes oxidative stress, inflammation, mitochondrial dysfunction, and impaired lactation in dairy cows. This study investigated whether FUNDC1 (FUN14 domain-containing protein 1)-associated mitochondrial quality control protects mammary tissue from oxidative stress-driven senescence and whether cinnamon polysaccharide (CP) can restore this pathway during mastitis recovery. Mastitis-associated oxidative stress reduced FUNDC1 expression, disrupted mitochondrial dynamics by suppressing fusion and promoting fission, decreased mitochondrial membrane potential, and increased senescence markers in bovine mammary epithelial cells. FUNDC1 overexpression alleviated mitochondrial dysfunction and senescence-associated changes. Mechanistically, the E3 ubiquitin ligase FANCL contributed to the proteasome-dependent reduction of FUNDC1 under oxidative stress. CP treatment restored FUNDC1 expression, reduced inflammation and oxidative stress, improved mitochondrial homeostasis, and enhanced postmastitis milk-yield recovery when combined with antibiotic treatment. These findings identify the FANCL–FUNDC1 axis as a link between oxidative stress and mammary gland senescence and support CP as a functional adjunct for mastitis management.
Abstract Alternative splicing (AS) of FgSdhC1 was identified in SDHI-sensitive (FgS) and intrinsically resistant (FgR) Fusarium graminearum isolates, generating four AS isoforms in each background. Isogenic replacement assays showed that individual isoforms differentially altered sensitivity to pydiflumetofen, boscalid, and fluopyram and affected multiple fitness-related traits. The average compound fitness index of FgR-derived isoform replacement strains was 0.54, compared with 0.20 for FgS-derived strains, and FgRAD2-C showed the highest value (1.43). FgSIR and FgSAD3 transcripts were significantly more abundant in FgS-C than the corresponding FgR-derived isoforms in FgR-C. Isoform transcript abundance, SDH activity, carbon source utilization, and responses to environmental stresses also differed among replacement strains. Transcriptomic and RT-qPCR analyses identified FgPRPF4B, FgDHX38/FgPRP16, and FgPPIL1 as differentially expressed candidate splicing-related genes. Collectively, these findings showed that FgSdhC1 alternative splicing isoforms differentially modulate intrinsic SDHI resistance and biological fitness in F. graminearum.
