Lovastatin reversed the enhanced sphingomyelin caused by 27-hydroxycholesterol in cultured vascular endothelial cells

Statins have pleiotropic properties which are involved in inhibiting the thrombogenic response. In this study, the effects of lovastatin on two phospholipids, phosphatidylcholine and sphingomyelin, were studied in cultured endothelial cells in the presence of an oxysterol, 27-hydroxycholesterol. After the cells were cultured with 50 nM of lovastatin for 60 h, lovastatin was found to decrease the incorporation of [³H]choline into phosphatidylcholine and sphingomyelin, inhibited CTP: phosphocholine cytidylyltransferase (CT) activity without altering the activity of sphingomyelin synthase and neutral sphingomyelinase. And lovastatin was not found to have a direct inhibitive effect on activity of CT. Exogenous mevalonic acid or cholesterol reversed the reduction of cholesterol concentration that was caused by lovastatin, but had no significant effect on the diminished [³H]sphingomyelin by lovastatin. The increase of [³H]sphingomyelin by 27-hydroxycholesterol was not detected in the presence of lovastatin. These findings suggest that (1) lovastatin can reduce sphingomyelin content by means of inhibiting phosphatidylcholine synthesis; and (2) The decrease in sphingomyelin is not related to the diminished cholesterol concentration or mevalonate-derived intermediates. This inhibitive effect of lovastatin on sphingomyelin may benefit cellular calcification caused by sphingomyelin.     

Graphene oxide supported rhombic dodecahedral Cu2O nanocrystals for the detection of carcinoembryonic antigen

In this work, a simple electrochemical immunosensor was developed for the detection of carcinoembryonic antigen (CEA) based on rhombic dodecahedral Cu₂O nanocrystals–graphene oxide–gold nanoparticles (rCu₂O–GO–AuNPs). GO as the template and surfactant resulting in rCu₂O exhibit improved rhombic dodecahedral structure uniformity and excellent electrochemical performance. Moreover, GO was found to be able to effectively improve the long stability of rCu₂O on the electrode response. Under optimal conditions, the immunosensor showed a low limit of detection (0.004 ng ml⁻¹) and a large linear range (0.01–120 ng ml⁻¹). This work presents a potential alternative for the diagnostic applications of GO-supported special morphology materials in biomedicine and biosensors.     

Irregular xylem 7 (IRX7) is required for anchoring seed coat mucilage in Arabidopsis

Large quantities of mucilage are synthesized in seed coat epidermis cells during seed coat differentiation. This process is an ideal model system for the study of plant cell wall biosynthesis and modifications. In this study, we show that mutation in Irregular Xylem 7 (IRX7) results in a defect in mucilage adherence due to reduced xylan biosynthesis. IRX7 was expressed in the seeds from 4 days post-anthesis (DPA) to 13 DPA, with the peak of expression at 13 DPA. The seed coat epidermis cells of irx7 displayed no aberrant morphology during differentiation, and these cells synthesized and deposited the same amount of mucilage as did wild type (WT) cells. However, the distribution of the water-soluble vs. adherent mucilage layers was significantly altered in irx7 compared to the WT. Both the amount of xylose and the extent of glycosyl linkages of xylan was dramatically decreased in irx7 water-soluble and adherent mucilage compared to the WT. The polymeric structure of water-soluble mucilage was altered in irx7, with a total loss of the higher molecular weight polymer components present in the WT. Correspondingly, whole-seed immunolabeling assays and dot-immunoassays of extracted mucilage indicated dramatic changes in rhamnogalacturonan I (RG I) and xylan epitopes in irx7 mucilage. Furthermore, the crystalline cellulose content was significantly reduced in irx7 mucilage. Taken together, these results indicate that xylan synthesized by IRX7 plays an essential role in maintaining the adhesive property of seed coat mucilage, and its structural role is potentially implemented through its interaction with cellulose.