Melanosomes are specialized membrane-bound organelles within which melanin is synthesized and stored.The levels of melanin can be effectively reduced by inhibiting melanin synthesis or promoting melanosome degradation...Melanosomes are specialized membrane-bound organelles within which melanin is synthesized and stored.The levels of melanin can be effectively reduced by inhibiting melanin synthesis or promoting melanosome degradation via autophagy.Ceramide,a central molecule in sphingolipid metabolism,has been widely implicated in the regulation of autophagy.Few researchers have addressed the potential effects of ceramide analogs on suppressing melanin synthesis.However,whether ceramide can induce melanosome autophagy and the potential autophagy-dependent mechanism underlying this phenomenon remain unknown.Here,an active compound from the marine microalgae Emiliania huxleyi extract was firstly isolated and identified as a long-chain C22-ceramide(C22-Cer).In vitro results of mouse B16 melanoma cell experiments showed that treatment with 2-5µmol/L C22-Cer significantly suppressed the increase ofα-MSH-induced melanin levels and tyrosinase activity without cytotoxicity.C22-Cer induced typical hallmarks of autophagy such as accumulation of autophagosomes,enhanced autophagic flux and microtubule-associated protein light chain 3,LC3-II expression,and p62 degradation through activating c-Jun N-terminal kinase(JNK)directly.Furthermore,C22-Cer activated JNK-Bcl-2 signaling,dissociated the Beclin1/Bcl-2 complex,and induced melanosome autophagy without affecting the expression of MITF.Besides,the Ca^(2+)influx induced by treatment with C22-Cer further increased the substantial accumulation of autophagosomes.Together,we found a novel marine-derived compound,C22-Cer,targeting JNK pathway and Ca^(2+)signaling to induce melanosome autophagy and suppress melanin accumulation in B16 cells.This study implicates that C22-Cer might be a potential therapeutic mediator against skin pigmentation in mammals.展开更多
The Hastelloy C22 coatings on Q235 steel substrate were produced by high power diode laser cladding technique. Their corrosion behaviors in static and cavitation hydrochloric, sulfuric and nitric acid solutions were i...The Hastelloy C22 coatings on Q235 steel substrate were produced by high power diode laser cladding technique. Their corrosion behaviors in static and cavitation hydrochloric, sulfuric and nitric acid solutions were investigated. The electrochemical results show that corrosion resistance of coatings in static acid solutions is higher than that in cavitation ones. In each case, coating corrosion resistance in descending order is in nitric, sulfuric and hydrochloric acid solutions. Obvious erosion-corrosion morphology and serious intercrystalline corrosion of coating are noticed in cavitation hydrochloric acid solution. This is mainly ascribed to the aggressive ions in hydrochloric acid solution and mechanical effect from cavitation bubbles collapse. While coating after corrosion test in cavitation nitric acid solution shows nearly unchanged surface morphology. The results indicate that the associated action of cavitation and property of acid solution determines the corrosion development of coating. Hastelloy C22 coating exhibits better corrosion resistance in oxidizing acid solution for the stable formation of dense oxide film on the surface.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42076086 and 32202068)Fujian Province Natural Science Foundation of China(Nos.2019J01696 and 2022J01332)the Fujian Province Young and Middle-Aged Teacher Education Research Project(No.JAT200247).
文摘Melanosomes are specialized membrane-bound organelles within which melanin is synthesized and stored.The levels of melanin can be effectively reduced by inhibiting melanin synthesis or promoting melanosome degradation via autophagy.Ceramide,a central molecule in sphingolipid metabolism,has been widely implicated in the regulation of autophagy.Few researchers have addressed the potential effects of ceramide analogs on suppressing melanin synthesis.However,whether ceramide can induce melanosome autophagy and the potential autophagy-dependent mechanism underlying this phenomenon remain unknown.Here,an active compound from the marine microalgae Emiliania huxleyi extract was firstly isolated and identified as a long-chain C22-ceramide(C22-Cer).In vitro results of mouse B16 melanoma cell experiments showed that treatment with 2-5µmol/L C22-Cer significantly suppressed the increase ofα-MSH-induced melanin levels and tyrosinase activity without cytotoxicity.C22-Cer induced typical hallmarks of autophagy such as accumulation of autophagosomes,enhanced autophagic flux and microtubule-associated protein light chain 3,LC3-II expression,and p62 degradation through activating c-Jun N-terminal kinase(JNK)directly.Furthermore,C22-Cer activated JNK-Bcl-2 signaling,dissociated the Beclin1/Bcl-2 complex,and induced melanosome autophagy without affecting the expression of MITF.Besides,the Ca^(2+)influx induced by treatment with C22-Cer further increased the substantial accumulation of autophagosomes.Together,we found a novel marine-derived compound,C22-Cer,targeting JNK pathway and Ca^(2+)signaling to induce melanosome autophagy and suppress melanin accumulation in B16 cells.This study implicates that C22-Cer might be a potential therapeutic mediator against skin pigmentation in mammals.
文摘The Hastelloy C22 coatings on Q235 steel substrate were produced by high power diode laser cladding technique. Their corrosion behaviors in static and cavitation hydrochloric, sulfuric and nitric acid solutions were investigated. The electrochemical results show that corrosion resistance of coatings in static acid solutions is higher than that in cavitation ones. In each case, coating corrosion resistance in descending order is in nitric, sulfuric and hydrochloric acid solutions. Obvious erosion-corrosion morphology and serious intercrystalline corrosion of coating are noticed in cavitation hydrochloric acid solution. This is mainly ascribed to the aggressive ions in hydrochloric acid solution and mechanical effect from cavitation bubbles collapse. While coating after corrosion test in cavitation nitric acid solution shows nearly unchanged surface morphology. The results indicate that the associated action of cavitation and property of acid solution determines the corrosion development of coating. Hastelloy C22 coating exhibits better corrosion resistance in oxidizing acid solution for the stable formation of dense oxide film on the surface.
