Bioscience, Biotechnology, and Biochemistry最新文献

Carbon catabolite repression (CCR) enables microorganisms to preferentially utilize energetically favorable carbon sources. In Aspergillus oryzae, the transcription factor CreA plays a central role in carbon source metabolism via CCR, although its function under various culture conditions remains insufficiently determined. In this study, we performed genomic systematic evolution of ligands via exponential enrichment-sequencing (gSELEX-Seq) using the DNA-binding domain of CreA to identify candidate CreA-binding regions within the genome. Motif analysis revealed a consensus binding site overlapping the previously reported 5'-SYGGRG-3' core. RNA-Seq analysis using the A. oryzae ΔcreA strain cultured under CCR release conditions revealed significant differences in the expression of 486 genes, including transporters, transcription factors, and sugar metabolism enzymes. Integration of gSELEX-Seq data and transcriptome profiles revealed nine candidate genes directly regulated by CreA. These findings enhance our understanding of the multifaceted regulatory network of CreA in A. oryzae, providing a framework for further functional studies.

Some fungi form fairy rings by secreting fairy chemicals that regulate plant growth. Among them, 2-azahypoxanthine (AHX) has been proposed as a new phytohormone, but its mechanisms remain unclear. We treated Arabidopsis thaliana with 400 μm AHX and observed growth inhibition, contrasting with earlier reports in bentgrass. To elucidate this effect, we performed transcriptome sequencing and identified differentially expressed genes. Gene ontology enrichment revealed activation of hormone- and stress-related terms and suppression of photosynthesis-related terms. Liquid chromatography-mass spectrometry further showed an increase in 1-aminocyclopropanecarboxylic acid, an ethylene precursor, after AHX treatment. These results suggest that AHX alters the stress response in A. thaliana by regulating genes associated with multiple plant hormones, including abscisic acid, ethylene, jasmonic acid, salicylic acid, and cytokinins.

Seafood processing wastewater, rich in organic carbon and nutrients, represents a potential low-cost medium for algal biomass cultivation. Here, we evaluated the growth performance of a naturally adapted microalgae-bacterial consortium isolated from a seafood processing facility primarily handling skipjack tuna. The consortium was cultured directly in raw wastewater without nutrient supplementation. Within 9 days, chlorophyll concentration increased fivefold and total suspended solids nearly doubled, indicating substantial biomass accumulation. Dissolved organic carbon and phosphate declined by 85% and 68%, respectively, indicating nutrient assimilation by the microbial community. The culture also showed a pH increase, consistent with active photosynthetic carbon uptake. Ammonium transiently accumulated before declining during algal growth, while nitrate remained low and nitrite undetectable, indicating a nitrogen cycle dominated by ammonium with minimal oxidation. These results demonstrate the feasibility of valorizing seafood wastewater for microalgal biomass production and provide a basis for sustainable, resource-oriented applications of industrial effluents.

Methylotrophs live symbiotically with plants in the phyllosphere. Because the leaf surface is a harsh environment with light, temperature, and low trophic levels, microorganisms on the leaves may have oligotrophic metabolism or use light energy to compensate for the low-carbon conditions for their growth. Various natural samples, including plants, have been screened for oligotrophic and/or light-driven methylotrophs.

This clinical trial assessed the effect of mayonnaise on postprandial glycemic responses to rice. Fifteen Japanese men consumed 150 g of rice with or without 15 g of mayonnaise (designated RM and R dishes, respectively). Blood samples were collected at 0, 30, 45, 60, 90, and 120 min postconsumption to measure glucose, insulin, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), and free fatty acid (FFA) levels. Compared to the R dish, the RM dish significantly reduced Δglucose at 30 and 45 min and the incremental area under the curve (iAUC) and ΔCmax of glucose. However, no significant differences were observed in Δinsulin. Meanwhile, ΔGIP and ΔFFA from 30 to 120 min and ΔGLP-1 at 30 and 45 min were significantly higher following RM dish intake. The iAUC of GIP and GLP-1, and ΔCmax of GIP were also elevated. These results indicate that adding mayonnaise suppresses postprandial glucose elevation and enhances incretin secretion.

We previously demonstrated that glucosamine (GlcN) exerts anti-inflammatory effects through the inhibition of nuclear factor-κB (NF-κB) signaling, possibly via O-linked-N-acetylglucosamine (O-GlcNAc) modification. In this study, we examined the effects of GlcN and alloxan (an inhibitor of O-linked-N-acetylglucosamine transferase) on NF-κB signaling molecules in interleukin (IL)-1β-stimulated human synovial MH7A cells. GlcN-induced O-GlcNAc modification of NF-κB and markedly inhibited IL-1β-induced nuclear translocation of the NF-κB, and phosphorylation of p65 subunit. GlcN also suppressed IL-1β-induced phosphorylation and degradation of inhibitor of κB (IκB). Moreover, GlcN promoted O-GlcNAc modification of IκB kinase (IKK) β, which phosphorylates IκBα, and concurrently inhibited its phosphorylation (activation). Notably, the effects of GlcN on NF-κB, IκBα, and IKKβ were reversed by alloxan. Finally, the inhibitory effect of GlcN on IL-8 production was eliminated in IKKβ-knockdown cells. Collectively, these findings indicate that O-GlcNAc modification of IKKβ is a key mediator of GlcN-induced suppression of NF-κB signaling and inflammatory cytokine production.

Chemotactic responses of Aurantiochytrium limacinum SR21 to 90 distinct compounds including sugars, organic acids, alcohols, amino acids, amines, aromatic compounds, sulfoxides, vitamins, nucleosides, and inorganic compounds were analyzed. While the zoospores were significantly attracted to several amino acids, they did not respond to their typical nutrients such as sugars or organic acids, suggesting that the chemotaxis may not be directly involved in the search for their nutrition. Zoospores were also attracted to vanillin, which is a component of lignin and a major component of land plant cell walls. This suggests that Aurantiochytrium sp. may be involved in the cycling of carbons in terrestrial plant biomass between land and sea via lignin. Structural comparisons of responding and nonresponding vanilloids indicated that the hydrocarbon chain at position 1, the alkoxyl group at position 3, and the hydroxyl group at position 4 may be particularly important in vanilloid recognition.

Diabetic nephropathy is a kidney disease aggravated by the uremic toxin indoxyl sulfate, which is produced from indole by the gut microbiota. Targeting the bacterial enzyme tryptophan indole-lyase (TIL), which produces indole from l-tryptophan, could be a promising therapeutic strategy. This study investigates diketopiperazines (DKPs), particularly cyclo-glycylproline [cyclo(Gly-Pro)], as potential TIL inhibitors. Cyclo(Gly-Pro) and other DKPs moderately inhibited indole production from l-tryptophan in crude bacterial extracts. Cyclo(Gly-Pro) was not metabolized by the bacteria and did not affect their viability. Cyclo(Gly-Pro) inhibited the Escherichia coli TIL with a Ki​ value of 17 μM through a mixed-type mechanism. Computational docking studies supported this finding, showing that cyclo(Gly-Pro) binds near the active site of TIL. Additionally, cyclo(Gly-Pro) significantly reduced indole production in bacterial cultures and human fecal samples. These findings suggest that cyclo(Gly-Pro) could be a promising dietary supplement or a lead compound for developing new therapeutics to prevent or treat diabetic nephropathy.

The intramolecular Diels-Alder reaction was employed for the assembly of the trans-decalin structure of cladoic acid, an anti-Trypanosoma cruzi active polyketide isolated from a fungus of the genus Cladosporium. Although the cycloaddition provided the desired trans-octalin as a minor product, the method was effective for simultaneously constructing four stereocenters in the B-ring of cladoic acid.

We herein report the collective synthesis of all known kauralexins (A1-A4 and B1-B4) and their putative biosynthetic intermediates isolated from Zea mays via a practical and scalable route. Our synthetic approach enabled stereoselective construction of key intermediates, clarified the stereochemical relationship between kauralexin A4 and annoglabasin E, and provided the first complete NMR spectroscopic data for kauralexins. Furthermore, we developed an efficient method for the selective synthesis of ent-isokaurene derivatives, facilitating the preparation of various oxidation products implicated in kauralexin biosynthesis. Our synthetic ent-kaurane library serves as valuable tools for biochemical investigations aimed at elucidating enzymatic functions involved in diterpenoid metabolism.