Bioscience, Biotechnology, and Biochemistry最新文献

We investigated whether an endoplasmic reticulum (ER) stress-inducing chemical tunicamycin (TM) modulates bile acid (BA) metabolism in rats. Male Wistar rats were intraperitoneally administered TM at 0.1 mg/kg body weight or vehicle, and samples were collected two days post-treatment. TM administration induced the levels of hepatic ER stress-related proteins. Increases were observed in both 12-hydroxylated and non-12-hydroxylated BA concentrations in the aortic plasma of the rats with TM treatment. Hepatic expression of Abcc3 that encodes BA transporter was significantly upregulated and positively correlated with the aortic BA levels. While these responses may not be exclusively attributable to ER stress and could partially arise from ER stress-independent effects of TM, these findings offer fundamental insights into BA metabolism in response to exogenous chemicals, and suggest that ER stress contributes to increased systemic BA circulation when hepatic function is compromised.

Concise and enantioselective synthesis of highly oxygenated cyclohexanoid natural products (+)-SDEF 678 metabolite and (+)-speciosins A, C, and L was achieved from commercially available D-quinic acid. This synthesis included diastereoselective nucleophilic epoxidation, Sonogashira cross-coupling, and β-elimination as common steps. Their absolute configurations were unambiguously determined by comparing optical rotations between the synthetic and natural products.

Optimum eating ripeness is critical when selecting peaches for consumption; however, the underlying sensory drivers remain unclear. This study identified the sensory factors characterizing the perceived optimum eating ripeness of melting flesh peach. Seven sample conditions were established from postharvest peaches based on the ripening days, where perceived ripeness shifted from unripe to optimum and then to overripe. The early phase was dominated by sensory textural changes (e.g. "crispiness") and the development of "peach-identity (ID)" flavor, while the late phase was predominated by an increase in "overripe" flavor. Instrumental firmness and ethyl acetate levels changed, accompanied by sensory textures and "overripe" flavor, respectively. These physicochemical indicators distinguished samples in different ripening phases. These findings highlight key sensory and physicochemical indicators for evaluating the optimum eating ripeness in peaches, reflecting the relationship between human perception and fruit biochemical changes and providing a foundation for improved postharvest quality management and consumer satisfaction.

Honey bee Apis mellifera L. adults exhibit a sterol composition dominated by phytosterols such as 24-methylene-cholesterol and β-sitosterol, while most insects possess cholesterol as a primary sterol. To examine whether sterol composition varies by social roles, we analyzed nurse bees and foragers using GC/MS. The analysis showed the four phytosterols, with 24-methylene-cholesterol being predominant. Honey, a dietary source for honey bees, contained more campesterol than in the whole body, suggesting possible metabolic use. Few significant differences in sterol compositions among tissues indicated that sterol metabolism is not tissue specific. However, social roles influenced different sterol compositions; nurse bees had higher β-sitosterol and isofucosterol, while foragers had more 24-methylene-cholesterol. Additionally, nurse bees retained more 24-methylene-cholesterol in their midgut. These findings suggest that sterol metabolism is influenced by social roles, probably due to differences in diet, absorption, or retention, rather than tissue dependent metabolism.

Epidemiological and experimental studies have shown that low methylmercury (MeHg) exposure causes cytotoxic effects. As to such cytotoxic effects, we have supposed that not only MeHg itself but also MeHg interacting with living environmental factors may cause cytotoxic effects. MeHg exposure is known to induce oxidative stress and cell death via ferroptosis in hepatocytes. In this study, we examined whether MeHg exposure followed by palmitic acid (PA) exposure at low non-toxic concentrations cause oxidative stress and cell death in HepG2 cells. In HepG2 cells combinedly exposed to MeHg and PA at low non-toxic concentrations, cell viability and glutathione peroxidase 4 expression levels were significantly decreased, while reactive oxygen species level was significantly increased. Ferrostatin-1 pretreatment suppressed oxidative stress and cell death found in the HepG2 cells. These results indicate that combined exposure to MeHg and PA at low non-toxic concentrations induces oxidative stress associated cell death in HepG2 cells.

Type Ⅱ diabetes and hypertension often coexist, affecting each other. Suppressing dipeptidyl peptidase-4 (DPP-Ⅳ) and angiotensin-I-converting enzyme (ACE) activity is crucial for managing these conditions. Lentinula edodes-stem protein, rich in hydrophobic amino acids, has potential for creating DPP-Ⅳ and ACE inhibitory peptides. This study used this protein, combined with databases, to derive peptides that exhibit dual inhibition of DPP-Ⅳ and ACE activity via enzymatic hydrolysis by Bacillus subtilis protease. The most active fraction (F1-2) had IC50 values of 0.0910 mg/mL (DPP-Ⅳ) and 0.0189 mg/mL (ACE). Following sequencing of fraction F1-2, screening, and solid-phase synthesis, three novel peptides (EW-1, WR-2, and LP-3) exhibiting >60% inhibition of both DPP-Ⅳ and ACE at 1 mg/mL. These peptides showed no significant toxicity to Caco-2 cells, indicating safety. These findings suggest that peptides derived from the stem of Lentinula edodes are promising candidates for health products targeting type Ⅱ diabetes and hypertension.

Tryptanthrin, an ingredient of Persicaria tinctoria, has been reported to exhibit antioxidant and anti-inflammatory effects. To elucidate the potential role of tryptanthrin in periodontal disease, we investigated its effects on bone metabolism and innate immunity, including the epithelial barrier. RAW264.7 cells were cultured with soluble receptor activator of nuclear factor-κB ligand (sRANKL) and tryptanthrin, and stained with Tartrate-Resistant Acid Phosphatase (TRAP) to evaluate osteoclastgenesis. The expression of osteoclast differentiation markers was examined using western blot analysis. OBA-9 cells were cultured with tryptanthrin, and the expression of tight junction (TJ) proteins and cell adhesion molecules (CAMs) was examined by western blot analysis. We found that tryptanthrin significantly inhibited osteoclastgenesis and suppressed the expression of osteoclast differentiation markers. Further, tryptanthrin enhanced the expression of TJ proteins and CAMs. These results indicated that tryptanthrin inhibits osteoclastgenesis by downregulating the osteoclast differentiation markers and enhances cell-cell adhesion by upregulating TJ proteins and CAMs.

Resistance to inhibitors of cholinesterase 8B (RIC8B) functions as a chaperone and guanine nucleotide exchange factor for Gαs/olf. We focused on RIC8B variant 1 (v1), which is abundantly expressed at the mRNA level, and variant 4 (v4), which lacks the C-terminal Cradle Loop Helix (CLH) domain. Together with three closely related variants (v2, v3, and v10), we evaluated five variants for chaperone activity. HEK293T cells were co-expressed with olfactory receptors (ORs), and odorant-induced cAMP production was used as a functional readout. Among the variants tested, only v4 consistently suppressed cAMP responses. AlphaFold3-based complex structure prediction indicated that v1 forms multiple hydrogen bonds with Gαs via its CLH domain, whereas v4 failed to establish these interactions. This suggests that v4 may be unable to stably adopt the proper binding conformation with Gαs, potentially resulting in improperly folded Gαs that exert a dominant-negative effect on OR responses.

Peptone is a promising raw material for culturing microorganisms and mammalian cells, but its composition remains unclear. Here, 36 different peptones were comprehensively quantified using five approaches: gas chromatography/tandem mass spectrometry, liquid chromatography/mass spectrometry, ion chromatography, post-column detection-high-performance liquid chromatography, and inductively coupled plasma mass spectrometry (named multimodal targeting analysis). Seventy-eight chemical compounds/ions were detected among 121 targets, including amino acids, nucleic acids, organic acids, sugars, vitamins, and minerals. The sum of the quantitated component weights exceeded 65% of the total weight in all cases (mean 88%). Principal component and cluster dendrogram analyses revealed clear distinctions between not only peptone brands but also production lots. Plant peptones exhibited greater variety than casein and meat peptones. Partial least squares analysis identified components specific to particular manufacturing processes and peptone sources. Acid-digested peptones contained more free amino acids, including Ala, Cys, Gly, Thr, Ser, Asp, Glu, and Pro, than enzyme-digested types.

Acetic acid bacteria (AAB) produce phosphatidylcholine (PC) as a major membrane component. PC has long been considered important for acetic acid tolerance in AAB, yet direct experimental support remains limited, and its physiological roles under diverse environmental stresses are not well defined. In this study, we constructed PC-deficient mutants of Acetobacter pasteurianus by deleting the phosphatidylethanolamine N-methyltransferase gene. PC deficiency resulted in phosphatidylglycerol accumulation and a tendency toward acyl-chain shortening. Phenotypic analysis showed that PC deficiency impaired growth under ionic, heat, and acidic stresses, indicating that PC supports membrane integrity under these stress conditions. Heterologous expression of PC synthase from Pseudomonas aeruginosa enabled choline-dependent regulation of PC biosynthesis. This system revealed that even low PC levels are sufficient to restore normal growth and acetic acid fermentation. These findings suggest that PC has diverse physiological roles in AAB and its function does not necessarily depend on its abundance in the membrane.