7-Rhamnosylated Flavonols Modulate Homeostasis of the Plant Hormone Auxin and Affect Plant Development

Flavonols are a group of secondary metabolites that affect diverse cellular processes. They are considered putative negative regulators of the transport of the phytohormone auxin, by which they influence auxin distribution and concomitantly take part in the control of plant organ development. Flavonols are accumulating in a large number of glycosidic forms. Whether these have distinct functions and diverse cellular targets is not well understood. The rol1-2 mutant of Arabidopsis thaliana is characterized by a modified flavonol glycosylation profile that is inducing changes in auxin transport and growth defects in shoot tissues. To determine whether specific flavonol glycosides are responsible for these phenotypes, a suppressor screen was performed on the rol1-2 mutant, resulting in the identification of an allelic series of UGT89C1, a gene encoding a flavonol 7-O-rhamnosyltransferase. A detailed analysis revealed that interfering with flavonol rhamnosylation increases the concentration of auxin precursors and auxin metabolites, whereas auxin transport is not affected. This finding provides an additional level of complexity to the possible ways by which flavonols influence auxin distribution and suggests that flavonol glycosides play an important role in regulating plant development.     

Activation of transient receptor potential ankyrin 1 by quercetin and its analogs

The agonistic activity of quercetin and its analogs towards the transient receptor potential ankyrin 1 (TRPA1) has been experimentally investigated. The human TRPA1 was expressed in HEK293T cells using a tetracycline-inducible system. The activation of TRPA1 was evaluated by a fluo-4 fluorescence assay based on calcium sensing. The results of a structure–activity relationship study led to the selection of six flavonoids, all of which activated the TRPA1 channel in a dose-dependent manner. Notably, the activation of TRPA1 by these flavonoid aglycones was completely inhibited by the co-treatment of the HEK293T cells with the TRPA1-specific antagonist, HC-030031. Several flavonoid glycosides and metabolites were also evaluated, but did not activate the TRPA1 except for methylated quercetin. On the other hand, TRPV1 (vanilloid receptor) did not respond to any of the flavonoids evaluated in this study. Therefore, these data suggest that the flavonoids would be promising ligands for the TRPA1.     

Studies on the probing stimulants for the white-backed planthopper,Sogatella furcifera (Homoptera: Delphacidae) in rice plant (Oryza sativa L.)

To elucidate the probing stimulants in rice plants for the white-backed planthopper, Sogatella furcifera, bioassay-guided separations were conducted, which led to the isolation of four active compounds. Using NMR and LC-MS spectra, their structures were determined as isoorientin 2″-O-(6?-(E)-feruloyl)glucoside, isoorientin 2″-O-(6?-(E)-p-coumaroyl)glucoside, tricin 5-O-glucoside, and isoscoparin 2″-O-(6?-(E)-feruloyl)glucoside.     

云南不同种皮色地方稻种的总黄酮含量及其对种子萌发的影响

为了解不同种皮色地方稻种的总黄酮含量与其种子萌发品质的相关性,测定了17份云南地方稻种谷粒、糙米和谷壳的总黄酮含量,以及谷粒和糙米的发芽势、发芽率、发芽指数和活力指数4项萌发指标。结果表明,红皮和紫皮谷粒及糙米的总黄酮含量显著、极显著高于白皮,而谷壳的总黄酮含量则无明显差异。红皮谷粒的4项萌发指标均高于紫皮和白皮,但仅红皮与白皮谷粒之间的发芽势差异达到极显著水平;红皮糙米的4项萌发指标极显著地高于紫米和白米,且除发芽指数外,紫米的其他3项萌发指标显著或极显著地高于白米,表明有色种皮谷粒、糙米的总黄酮含量较高,其萌发指标也相应较高。相关分析表明,谷粒的总黄酮含量与4项萌发指标之间没有明显的相关性,但糙米的总黄酮含量则与4项萌发指标呈显著正相关;谷壳的黄酮含量与种子萌发无关,而糙米的黄酮含量则显著地影响种子的萌发特性。     

枇杷种质花中黄酮含量分析与评价

黄酮是枇杷花主要功效成分之一,具有显著的消炎止咳作用。本试验从国家果树种质福州枇杷圃中筛选国内外代表性枇杷种质55份,分析评价了其花中黄酮含量的差异及分级指标。研究结果显示,不同枇杷种质之间黄酮含量差异明显,分布范围为0.44%~2.28%,最高的卓南1号是最低者香钟25号的5.18倍;来源于福建的枇杷种质与浙江的存在极显著差异(P0.01),与贵州、广西的存在显著差异(P0.05);初步筛选出超高黄酮含量枇杷优异种质1份,初步建立了枇杷花黄酮分级指标,为今后枇杷花研究和利用奠定基础。     

Modulation of extracellular-matrix synthesized by cultured stromal cells from normal human breast tissue by epidermal growth factor

A routine, reproducible procedure was developed for the preparation and characterization of stromal cells from normal human breast tissue obtained by reduction mammaplasty. Isolates (n = 15) all exhibited enhanced rates of proliferation, even in the presence of 20% fetal calf serum, when exposed to epidermal growth factor or transforming growth factor a (both 10(-8) M). Cellular responsiveness to these growth factors was consistent with expression of specific surface receptors for epidermal growth factor (approximately 10(4)/cell). In cultures, stromal cells elaborated an extensive, cross-linked, insoluble extracellular matrix which remained firmly associated with the plastic surface of tissue culture ware upon lysis of cells. The insoluble matrix material was analyzed using enzymatic digestion procedures following incorporation of radiolabelled precursors into macromolecular material prior to lysis and preparation. The relative proportion of glycoconjugate (glycopeptides and proteoglycans) and collagenous material present in matrix material was approximately 45% and approximately 55%, respectively, and this was modulated by inclusion of epidermal growth factor into culture medium to approximately 60% and approximately 40%, respectively. Under similar culture conditions stromal cells synthesized twice as much hyaluronate as was produced by control cultures. By use of specific antibody preparations we identified at least four species of glycopeptide present in stromal matrices (namely, fibronectin, laminin, tenascin, and thrombospondin) as well as three types of collagen (types I, III, and IV). The rapid and reproducible procedure for the preparation of radiolabelled insoluble matrix material from normal human breast tissue allows for the study of cellular interaction involving extracellular matrix turnover and degradation.     

Rhamnocitrin-3-glucuronid in Verbesina myricephala

The structure of a new flavonol-glycoside isolated from the herb of Verbesina myricephala Sch. Bip. has been established as the 3-O-β-d-glucopyranuronide of 3,5,4′-trihydroxy-7-methoxy-flavone (rhamnocitrin-3- glucuronide.     

Phytochrome-induced flavonoid biosynthesis in mustard (Sinapis alba L.) cotyledons. Enzymic control and differential regulation of anthocyanin and quercetin formation

Phytochrome-induced increases in enzyme activities for phenylalanine ammonia-lyase (EC 4.3.1.5) and chalcone isomerase (EC 5.5.1.6), and in amounts of the related end products, anthocyanin and the flavonol, quercetin, were measured in cotyledons of mustard (Sinapis alba L.). There was no correlation between the activities of these enzymes and the rate of anthocyanin accumulation; however, some correlation was found with the quercetin accumulation rate. Since anthocyanin and flavonol accumulation is spatially separated in mustard (flavonols in the upper epidermis, anthocyanin in the lower epidermis), it was possible to measure anthocyanin-associated phenylalanine ammonia-lyase independently. This activity correlated well with the accumulation rate for anthocyanin during the first few hours after induction. The phytochrome effect on anthocyanin formation differed from that on quercetin formation: anthocyanin was strongly induced by continuous far-red light and by both continuous red light and red light pulses, whereas quercetin was only effectively induced by continuous far-red light.Abbreviations CHI chalcone isomerase - PAL phenylalanine ammonia-lyase     

Heterogeneity of the ABH antigenic determinants expressed in human pyloric and duodenal mucosae

We defined the chemical structure and the genetic control of the various A or B determinants expressed by pyloric and duodenal epithelial cells by indirect immunofluorescent staining using monoclonal anti-A or anti-B reagents that recognize only certain variants of A or B antigenic determinants.Some mucous cells in pyloric and Brünner's glands express AY or BY antigens whereas other mucous cells in the same glands express only the Y antigen. Absorptive and goblet cells of the duodenal villi and Lieberkühn glands express mono- and difucosylated A or B structures, mainly of type 1. The pyloric surface epithelium expresses mono- and difucosylated, type 1 and type 2, A or B structures. In addition, A or B antigens, with a so far undefined structure are found in the pyloric surface mucosae of non-secretor individuals.