The colonic groove of the plains viscacha (Lagostomus maximus): Histochemical evidence of an abrupt change in the glycosylation pattern of goblet cells

The ascending colon of most rodent species shows a longitudinal colonic groove that works as a retrograde transport pathway for a mixture of bacteria and mucus toward the cecum. We describe the morphology and glycosylation pattern of the colonic groove of Lagostomus maximus to analyze the role of mucins in this anatomical feature. We also studied the distribution pattern of the interstitial cells of Cajal (ICC) to evaluate their regulatory influence on gut motility. The groove originated near the cecocolic junction and extended along the mesenteric side of the ascending colon, limited at both ends by nonpapillated ridges. These ridges divided the lumen of the ascending colon into two compartments: a narrow channel and a large channel, called the groove lumen and the main lumen, respectively. The histochemical analysis showed differences in the glycosylation pattern of the goblet cells inside and outside the groove. Unlike the mucosa lining the main lumen of the colon, the groove was rich in goblet cells that secrete sulfomucins. The PA/Bh/KOH/PAS technique evidenced an abrupt change in the histochemical profile of goblet cells, which presented a negative reaction in the groove and a strongly positive one in the rest of the colonic mucosa. The anti‐c‐kit immunohistochemical analysis showed different ICC subpopulations in the ascending colon of L. maximus . Of all types identified, the ICC‐SM were the only cells located solely within the colonic groove.     

Flavonoid aglycones from leaf resins of two species of Heterotheca (compositae)

Twenty-nine flavonoid aglycones have been identified from two populations each of Heterotheca grandiflora and H. psammophila. Considerable qualitative variation was found between populations of the same species. Overall, H. grandiflora is more complex in its flavonoid profile, accumulating a total of 24 compounds based on eight skeletal types, compared with 13 compounds based on four skeletal types in H. psammophila.     

Protein-carbohydrate complementarity in mammalian gamete recognition

Recent studies suggest that gamete recognition in a number of species is mediated by complementary proteins and carbohydrates on opposing gamete surfaces. Studies in invertebrates and vertebrates have shown that carbohydrate-binding proteins on the sperm surface recognize and bind to complementary glycoconjugates on the egg's extracellular coat. This chapter reviews our current knowledge of gamete recognition in the mouse. The complementary receptors for both mouse sperm and egg have been identified, purified, and characterized. Their synthesis during gametogenesis has been defined, as have the effects of sperm capacitation and of the acrosome reaction on their expression and distribution. Their relationship to gamete receptors that function in other species is discussed. Finally, evidence is presented that suggests that one of the receptors that mediate mouse gamete recognition belongs to a family of cell surface receptors that function during multiple cellular interactions in development.     

New Flavonoid Glucuronate Esters with Anti‐inflammatory Activities from Scutellaria regeliana

Two new flavonoid glucuronate esters, named scuregeliosides A and B ( 1 and 2 ), as well as three known ones, chrysin‐7‐O‐β‐d ‐glucuronic acid methyl ester ( 3 ), 5,7,4′‐trihydroxyflavone‐8‐O‐β‐d ‐glucuronic acid methyl ester ( 4 ) and apigenin‐7‐O‐β‐d ‐glucuronic acid ethyl ester ( 5 ), were isolated from the ethanolic extract of the whole plant of Scutellaria regeliana. Their chemical structures were elucidated on the basis of comprehensive spectroscopic analyses. Five compounds were screened for anti‐inflammatory activity in vitro. As the results, the inhibition rates of release of β‐glucuronidase from rat polymorphonuclear leukocytes were in the range of 42.2 – 47.1% at a concentration of 10 μm .     

Variation in Polyphenolic Profiles,Antioxidant and Antimicrobial Activity of Different Achillea Species as Natural Sources of Antiglycative Compounds

A comparative study was carried out on the methanolic extracts from six Achillea species and the examined polyphenols from these plants on the formation of advanced glycation end‐products (AGE) in vitro. A. pachycephala which was richer in flavonoids (15 mg quercetin/g W) and phenolics (111.10 mg tannic acid/g DW) with substantial antioxidant activity (IC₅₀ = 365.5 μg/ml) presented strong anti‐AGE properties. Chlorogenic acid, luteolin, quercetin and caffeic acid were identified as the major polyphenols in the extracts by HPLC. In general, polyphenolic content follows the order of A. pachycephalla > A. nobilis > A. filipendulina > A. santolina > A. aucheri > A. millefolium. Most extracts exhibited marked anti‐AGE ability in the bovine serum albumin (BSA)/methylglyoxal (MG) system, though A. pachycephala showed the highest potential. The formation of AGEs was assessed by monitoring the production of fluorescent products and circular dichroism (CD) spectroscopy. Diminution in free radical production (assessed by 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) assays) is discussed as potential mechanism for delay or reduced AGE. The results demonstrate the antiglycative, antioxidant and antimicrobial potential of Achillea species which can be attributed to polyphenols content and the effectiveness on generation of AGEs, thus Achillea species can be considered as natural sources for slowing down glycation related diseases.     

Identification and characterization of a rhamnosyltransferase involved in rutin biosynthesis in Fagopyrum esculentum (common buckwheat)

Rutin, a 3-rutinosyl quercetin, is a representative flavonoid distributed in many plant species, and is highlighted for its therapeutic potential. In this study, we purified uridine diphosphate-rhamnose: quercetin 3-O-glucoside 6″-O-rhamnosyltransferase and isolated the corresponding cDNA (FeF3G6″RhaT) from seedlings of common buckwheat (Fagopyrum esculentum). The recombinant FeF3G6″RhaT enzyme expressed in Escherichia coli exhibited 6″-O-rhamnosylation activity against flavonol 3-O-glucoside and flavonol 3-O-galactoside as substrates, but showed only faint activity against flavonoid 7-O-glucosides. Tobacco cells expressing FeF3G6″RhaT converted the administered quercetin into rutin, suggesting that FeF3G6″RhaT can function as a rhamnosyltransferase in planta. Quantitative PCR analysis on several organs of common buckwheat revealed that accumulation of FeF3G6″RhaT began during the early developmental stages of rutin-accumulating organs, such as flowers, leaves, and cotyledons. These results suggest that FeF3G6″RhaT is involved in rutin biosynthesis in common buckwheat.     

中国水仙NtMYB7基因的克隆及功能初步研究

为研究中国水仙类黄酮代谢调控网络,从中国水仙(Narcissus tazetta var.chinensis)中克隆得到一个R2R3-MYB基因,命名为NtMYB7(GenBank登录号:MF522208)。序列分析表明,NtMYB7基因cDNA开放阅读框(ORF)为753bp,编码250个氨基酸。氨基酸多重序列比对分析发现,NtMYB7含有R2和R3保守结构域,属于R2R3-MYB家族;系统进化树分析结果显示,NtMYB7与花青素合成抑制因子聚为一类。实时荧光定量PCR分析发现,NtMYB7基因在中国水仙不同时期花瓣和副冠以及不同器官中均有表达,且NtMYB7基因在鳞茎盘中表达量最高。瞬时表达分析发现,NtMYB7使花青素合成激活因子StMYB诱导产生的红色变浅;定量PCR分析表明,NtMYB7基因显著抑制烟草黄酮醇代谢分支FLS基因的表达,同时抑制StMYB激活的花青素和原花青素合成结构基因的表达。研究结果初步判断,NtMYB7基因是中国水仙类黄酮代谢途径的抑制因子。     

Physical interactions among flavonoid enzymes in snapdragon and torenia reveal the diversity in the flavonoid metabolon organization of different plant species

Flavonoid metabolons (weakly‐bound multi‐enzyme complexes of flavonoid enzymes) are believed to occur in diverse plant species. However, how flavonoid enzymes are organized to form a metabolon is unknown for most plant species. We analyzed the physical interaction partnerships of the flavonoid enzymes from two lamiales plants (snapdragon and torenia) that produce flavones and anthocyanins. In snapdragon, protein–protein interaction assays using yeast and plant systems revealed the following binary interactions: flavone synthase II (FNSII)/chalcone synthase (CHS); FNSII/chalcone isomerase (CHI); FNSII/dihydroflavonol 4‐reductase (DFR); CHS/CHI; CHI/DFR; and flavonoid 3′‐hydroxylase/CHI. These results along with the subcellular localizations and membrane associations of snapdragon flavonoid enzymes suggested that FNSII serves as a component of the flavonoid metabolon tethered to the endoplasmic reticulum (ER). The observed interaction partnerships and temporal gene expression patterns of flavonoid enzymes in red snapdragon petal cells suggested the flower stage‐dependent formation of the flavonoid metabolon, which accounted for the sequential flavone and anthocyanin accumulation patterns therein. We also identified interactions between FNSII and other flavonoid enzymes in torenia, in which the co‐suppression of FNSII expression was previously reported to diminish petal anthocyanin contents. The observed physical interactions among flavonoid enzymes of these plant species provided further evidence supporting the long‐suspected organization of flavonoid metabolons as enzyme complexes tethered to the ER via cytochrome P450, and illustrated how flavonoid metabolons mediate flower coloration. Moreover, the observed interaction partnerships were distinct from those previously identified in other plant species (Arabidopsis thaliana and soybean), suggesting that the organization of flavonoid metabolons may differ among plant species.     

The anti-oligosaccharide antibodies present in sera from patients with motor neuron disease and neuropathy recognize theN-glycolylneuraminic acid containing gangliotetrahexosyl oligosaccharide

We found that serum antibodies present in the serum of patients with motor neuron disease and neuropathy, which were previously shown to react with the oligosaccharide chain of ganglioside GM1(Neu5Ac), can be recognized and titred using theN-glycolylneuraminic acid containing monosialo-gangliotetrahexosylceramide, GM1(Neu5Gc), which is not a component of normal human cells. The antibody-antigen reaction was abolished by immunoabsorption with the free oligosaccharide chain. This result, together with the knowledge that these antibodies recognize several glycoconjugates, supports the conviction that these antibodies are non-specific for a gangliosidic structure.     

An improved ELISA for the determination of sialyl Lewisx structures on purified glycoconjugates

The membrane carbohydrate antigen, sialyl Lewis x (sLe^x), is involved in cellular adhesive interactions in many diseases, such as cancer, inflammation and thrombosis. This antigen is also found on soluble macromolecules, such as serum glycoproteins, but the precise role of soluble sLe^x in modifying disease processes, or reflecting the pathological changes is still unclear. Although methods were previously reported for the measurement of soluble sLe^x, many of these were not well characterised, measurements were mainly made on mixtures of molecules, and the anti-sLe^x antibodies were used at concentrations that made the assay expensive. In this study an ELISA has been devised that detects sLe^x in purified soluble glycoconjugates using the anti-sLe^x antibody, CSLEX 1. Commercially-available haptoglobin (Hp) and synthetic complexes of Lewis antigens with polyacrylamide were used as model substances in developing the procedure. Key steps were washing the antibody/antigen complex with ten times diluted salt solution to prevent dissociation of the complex and the use of bovine serum albumin for blocking non-specific interactions. The assay was shown to be very specific, its precision was in the range 6–12%, and it could detect less than a pmol of sLe^x. It could also distinguish between different densities of sLe^x on the same amount of glycoconjugate. Determination of sLe^x in Hp isolated from small groups of healthy individuals, cancer patients, and rheumatoid arthritis sufferers suggested that the antigen expression is increased in disease. This method, which is an improvement on those previously described, will be useful for determining sLe^x in many different types of soluble glycoconjugate, and used in combination with synthetic carbohydrate polyacrylamide complexes, will help to standardize measurements of soluble sLe^x in the future.