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In order to explore the effect of dietary supplementation of Clostridium butyricum on the volatile flavor substances in the meat of small-tailed Han sheep during postmortem aging and its possible mechanism, the Longissimus dorsi muscle of small-tailed Han sheep slaughtered at the age of six months was taken for postmortem maturation at 4 ℃, and then the volatile flavor substances, the contents of lipid metabolism-related enzymes including adenosine monophosphate activated protein kinase (AMPK), acetyl CoA carboxylase (ACC) and carnitine lipoyltransferase 1 (CPT1) were measured on days 0, 1, 2, 3, 4 and 5. The results of electronic nose test showed that the contents of alkanes, hydroperoxide and nitrogen oxides in the C. butyricum supplementation group were higher than in the control group without C. butyricum supplementation. According to the results of gas chromatography-mass spectrometry (GC-MS), the types of aldehydes, alcohols and ketones in the C. butyricum group were more than in the control group, while the contents of fatty oxidation products such as octanal, nonanal, decanal and heptaldehyde were obviously reduced. The key flavor substances common to both groups, as determined by relative odor activity value (ROAV), included octanal, nonanal, trans-2-decenal and 1-octen-3-ol, nonanal being the greatest contributor to the flavor of lamb meat. Compared with the control group, the contents of AMPK and CPT1 in the C. butyricum group decreased significantly during postmortem aging (P < 0.05), while the contents of ACC in the C. butyricum group were significantly higher than those in the control group at 0, 1, 3 and 5 days postmortem (P < 0.05). The correlation analysis showed that AMPK and CPT1 were significantly positively correlated with nonanal (P < 0.001), while ACC was significantly negatively correlated with nonanal and decanal (P < 0.001). In conclusion, the addition of C. butyricum to the diet can affect the volatile flavor substances in the meat of small-tailed Han sheep during postmortem aging by regulating the AMPK-ACC-CPT1 signaling pathway.

生物絮凝法收获微藻细胞具有毒性小、成本低、效率高等优点。为揭示产卟啉杆菌（Porphyrobacter）对棕鞭藻絮凝收获的影响机制，比较在BG11培养基、含5 g/L葡萄糖的BG11（glu+BG11）培养基中纯藻体系以及其与Porphyrobacter共培养体系中的棕鞭藻絮凝效率，并对不同体系中的胞外有机物（AOM）产量与组成及藻际细菌群落结构进行分析。结果表明：在BG11、glu+BG11纯藻培养体系中微藻絮凝效率分别为62.40%和19.02%，而当棕鞭藻与Porphyrobacter在glu+BG11体系中共培养时絮凝效率则高达93.42%，且此时AOM产量及AOM中多糖产量显著降低；对于glu+BG11体系，AOM中的阿拉伯糖、鼠李糖产量均在藻菌共培养时较高，且AOM所含的单糖种类与BG11体系相同；Porphyrobacter可使AOM中的蛋白质酰胺基团发生峰偏移，引起色氨酸、酪氨酸等蛋白质类物质的改变；相比纯藻培养体系，Porphyrobacter能适应棕鞭藻glu+BG11培养体系并成为优势菌属，同时存在芽孢杆菌属（Bacillus）、黄杆菌属（Flavobacterium）、短波单胞菌属（Brevundimonas）等细菌。产卟啉杆菌可显著降低棕鞭藻AOM产量并影响其组成，促进棕鞭藻絮凝。 Harvesting microalgae cells by bioflocculation has the advantages of low toxicity, low cost and high efficiency. In order to reveal the influence mechanism of Porphyrobacter on the flocculation harvest of Ochromonas sp., the flocculation efficiency of Ochromonas sp. in BG11 medium，BG11 medium containing 5 g/L glucose (glu+BG11) pure algal system and coculture system with Porphyrobacter were compared, and the algal organic matter (AOM) yield and composition and the community structure of bacteria in the phycosphere in different systems were analyzed. The results showed that the flocculation efficiency of microalgae in BG11 and glu+BG11 pure algal culture systems were 62.40% and 19.02% respectively. The flocculation efficiency in the coculture system of Ochromonas sp. and Porphyrobacter in glu+BG11 reached 93.42%, and the AOM yield and polysaccharide yield in AOM decreased significantly. For coculture system in glu+BG11, the yield of arabinose and rhamnose in AOM increased significantly, and the type of monosaccharide in AOM was the same as BG11 system. Porphyrobacter shifted the peak of protein amide group in AOM and caused the changes of protein substances such as tryptophan and tyrosine. Compared with the pure algal culture system, Porphyrobacter could adapt to the culture system of Ochromonas sp. as the dominant bacteria, while species of Bacillus, Flavobacterium and Brevundimonas appeared. Porphyrobacter can promote the flocculation of Ochromonas sp. through reducing the AOM yield of Ochromonas sp. and affecting its composition.

Formamide (HCONH2) plays a pivotal role in the manufacture of a diverse array of chemicals, fertilizers, and pharmaceuticals. Photocatalysis holds great promise for green fabrication of carbon‐nitrogen (C−N) compounds owing to its environmental friendliness and mild redox capability. However, the selective formation of the C−N bond presents a significant challenge in the photocatalytic synthesis of C−N compounds. This work developed a photocatalytic radical coupling method for the formamide synthesis from co‐oxidation of ammonia (NH3) and methanol (CH3OH). An exceptional formamide yield rate of 5.47±0.03 mmol ⋅ gcat−1 ⋅ h−1 (911.87±5 mmol ⋅ gBi−1 ⋅ h−1) was achieved over atomically dispersed Bi sites (BiSAs) on TiO2. An accumulation of 45.68 mmol ⋅ gcat−1 (2.0 g ⋅ gcat−1) of formamide was achieved after long‐term illumination, representing the highest level of photocatalytic C−N compounds synthesis. The critical C−N coupling for formamide formation originated from the "σ–σ" interaction between electrophilic ⋅CH2OH with nucleophilic ⋅NH2 radical. The BiSAs sites facilitated the electron transfer between reactants and photocatalysts and enhanced the nucleophilic attack of ⋅NH2 radical on the ⋅CH2OH radical, thereby advancing the selective C−N bond formation. This work deepens the understanding of the C−N coupling mechanism and offers an intriguing photocatalytic approach for the efficient and sustainable production of C−N compounds. [ABSTRACT FROM AUTHOR]

BackgroundActivated hepatic stellate cells are the main source of excessive collagen deposition in liver fibrosis. Here we report the inhibitory effects of the combinational treatment of two natural products, astragalus polysaccharide (APS) and β-elemene (ELE) on the activation of human liver hepatic stellate cell line LX-2 cells.MethodsCultured LX-2 cells were treated with different concentrations of APS or ELE for 24 or 48 hours. Cell viability/apoptosis was measured by MTT assay and Annexin V/PI staining , activation related genes including α-SMA and CD44 expressions were measured by real-time PCR and western blot respectively.ResultsThe majority of LX-2 cells showed morphological change in the presence of APS or ELE for 24 hours. Treatment with APS + ELE for 24 or 48 hours significantly inhabited the cell proliferation compared with APS or ELE treatment alone on LX-2 cells. APS + ELE may block the up-regulation of α-SMA and CD44 both in mRNA and protein levels through TGF-β pathway in LX-2 cells.ConclusionAPS or ELE treatment alone on LX-2 cells could inhibit cell proliferation and induce apoptosis. The combinational treatment using APS + ELE significantly increased the killing efficiency on LX-2 cells. α-SMA and CD44 expressions was inhibited upon APS + ELE treatment through TGF-β pathway in LX-2 cells. The results indicated a novel treatment using natural products for liver diseases with anti-fibrotic effect.

Cartilage is a kind of connective tissue that buffers pressure and is essential to protect joint movement. It is difficult to self-recover once cartilage is damaged due to the lack of blood vessels, lymph, and nerve tissues. Repair of cartilage injury is mainly achieved by stimulating chondrocyte proliferation and extracellular matrix (ECM) synthesis. Cartilage homeostasis involves the regulation of multiple growth factors and the transduction of cellular signals. It is a very complicated process that has not been elucidated in detail. In this review, we summarized a variety of signaling molecules related to chondrocytes function. Especially, we described the correlation between chondrocyte-specific regulatory factors and cell signaling molecules. It has potential significance for guiding the treatment of cartilage injury.