Arabidopsis U6 small nuclear RNA (snRNA) promoters are those transcribed by RNA polymerase III, but all the core elements for transcriptional initiation are located in the 5' promoter region. Previously, three Arabidopsis U6 snRNA genes (U6-1, U6-26, and U6-29) were identified. Herein, we have further identified three new U6 loci (U6-4, U6-5, and U6-6) in the Arabidopsis genome. Alignment of these revealed that the upstream sequence element and TATA elements were contained in six U6 promoters. In addition, a unique, highly conserved element named the "CAT" element was observed in the promoter region. To understand the expression patterns of these U6 genes in Arabidopsis, we fused these promoters to the DNA segment of β β β β β-glucuronidase and then transferred these six constructs into Arabidopsis. Real-time reverse transcription-polymerase chain reaction analysis of these fused transcripts indicated that the newly identified U6 genes are active in Arabidopsis and that the U6-26 promoter seems to have higher transcriptional activity in leaf, stem, flower and silique. These results help to understand the function of these U6 snRNAs in Arabidopsis. DB (2007). Varied transcriptional efficiencies of multiple Arabidopsis U6 small nuclear RNA genes.
The active fraction extracted from dragon's blood displayed an inhibitory effect on alpha-glucosidase activity with an IC50 of 0.152 mg/mL, which is nearly half of the crude material. Its inhibition on alpha-glucosidase was noncompetitive. In addition, when this fraction was orally administered to mice dosed with Acarbose (20 mg/kg), the active fraction (100, 300, 500 mg/kg) significantly suppressed increase of blood glucose levels after sucrose loading in a dose-dependent manner. These results suggest that this extract from dragon's blood exerts an anti-diabetic effect by suppressing intestinal carbohydrate absorption and thereby reducing the postprandial increase of blood glucose.
A new dihydrochalcone, 4'-hydroxy-4,2'-dimethoxy-dihydrochalcone, was isolated from Chinese dragon's blood, the red resin of Dracaena cochinchinensis. Its structure was established by spectrum analysis.
Abstract. The interaction between loureirin B (Lour B) and human serum albumin (HSA) was investigated by fluorescence and UV-vis absorption spectroscopy. Experimental results indicated that loureirin B had a strong ability to quench the intrinsic fluorescence of HSA through a dynamic quenching procedure. The fluorescence quenching data revealed that the quenching constants (K SV ) 2.68 × 10 4 , 3.30 × 10 4 and 4.10 × 10 4 l/mol at 300, 310 and 320 K, respectively. Based on the thermodynamic parameters obtained, the positive values of enthalpy change ΔH and entropy change ΔS suggested that hydrophobic forces played a major role in the interaction of Lour B with HSA. According to Förster theory of energy transfer, the distance r between HSA and Lour B was calculated to be 2.85 nm. Furthermore, the effect of Lour B on the conformation of HSA was analyzed by synchronous fluorescence and three-dimensional fluorescence spectra.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.