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Melibiose

About: Melibiose is a(n) research topic. Over the lifetime, 1002 publication(s) have been published within this topic receiving 27300 citation(s). The topic is also known as: Melibiose.


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Journal ArticleDOI
TL;DR: It is shown that most of human IgM antibodies present in the serum of healthy donors and reactive with pig cells react with galactose in an (alpha 1-3) linkage with Galactose--i.e., Gal(alpha 1,3)Gal.
Abstract: A major problem with pig-to-human-tissue xenograft studies is that humans have natural antibodies to pig cells; these antibodies would cause hyperacute rejection if pig tissues were xenografted to humans. Here we show that most of human IgM antibodies present in the serum of healthy donors and reactive with pig cells react with galactose in an (alpha 1-3) linkage with galactose--i.e., Gal(alpha 1-3)Gal. Absorption studies demonstrated that the antibodies detected the same or similar epitopes on the surface of pig erythrocytes, blood and splenic lymphocytes, and aortic endothelial cells (EC). The antibodies were sensitive to 2-mercaptoethanol (2ME) treatment, did not bind to protein A or G, and were present in the high molecular weight fraction of serum; they are clearly IgM antibodies. Further, the antibodies did not react with human ABO blood group substances and are not related to human blood group A or B, which carry a terminal galactose. The reaction of human serum with pig erythrocytes was specifically inhibited by mono- and disaccharides: D-galactose, melibiose, stachyose, methyl-alpha-D-galactopyranoside, and D-galactosamine but not by D-glucose or methyl-beta-D-galactopyranoside; demonstrating that the reaction is with galactose in an alpha and not a beta linkage. A cDNA clone encoding the murine alpha-1,3-galactosyltransferase (which transfers a terminal galactose residue with an (alpha 1-3) linkage to a subterminal galactose) was isolated by polymerase chain reaction (PCR), cloned, and transfected into COS cells, which are of Old World monkey origin and, like humans, do not express Gal(alpha 1-3)Gal. After transfection, COS cells became strongly reactive with human serum and with IB4 lectin [which reacts only with Gal(alpha 1-3)Gal]; this reactivity could be removed by absorption with pig erythrocytes. As most of the antibody reacting with pig cells can be removed by absorption with either melibiose or Gal(alpha 1-3)Gal+ COS cells, most of these react with Gal(alpha 1-3)Gal. These findings provide the basis for genetic manipulation of the pig alpha-1,3-galactosyltransferase for future transplantation studies.

604 citations

Journal ArticleDOI
TL;DR: Yeast transformed with GAL4-bearing plasmid become constitutive for expression of the galactose/melibiose genes, even in normally repressing (glucose) medium, indicating that the repressing effects of glucose, at least in part, are mediated by the product of the negative regulatory gene GAL80.
Abstract: GAL4 is a classically defined positive regulatory gene controlling the five inducible structural genes of galactose/melibiose utilization in yeast. The positive regulatory function of the GAL4 gene product in turn is controlled by the product of another gene, the negative regulator GAL80. We have cloned a 3.1-kilobase fragment containing GAL4 by homologous complementation using the multicopy chimeric vector YEp24 and demonstrated that multiple copies of GAL4 in yeast have pronounced dosage effects on the expression of the structural genes. Yeast transformed with GAL4-bearing plasmid become constitutive for expression of the galactose/melibiose genes, even in normally repressing (glucose) medium. Multiple copies of the GAL4 plasmid also increase expression of the structural genes in inducing (galactose) medium and can partially overcome the effects of a dominant super-repressor mutant, GAL80S. Using an internal deletion in GAL4, we have demonstrated that these dosage effects are due to overproduction of GAL4 positive regulatory product rather than an effect of the flanking sequences titrating out a negative regulator. These results point to the importance of competitive interplay between the positive and negative regulatory proteins in the control of this system. We have also used the dosage effect of GAL4 plasmid in combination with different GAL4 and GAL80 alleles to create new phenotypes. We interpret these phenotypes as indicating that (i) the repressing effects of glucose, at least in part, are mediated by the product of the negative regulatory gene, GAL80, and (ii) the GAL80 protein may have specific interactions with the control regions of the structural genes.

328 citations

Journal ArticleDOI
TL;DR: A novel solvent-producing, anaerobic clostridium, strain P7(T), was isolated from sediment from an agricultural settling lagoon after enrichment with CO as the substrate and analysis of the 16S rRNA gene sequence showed that it was closely related to Clostridial scatologenes ATCC 25775(T) (99.7% sequence similarity).
Abstract: A novel solvent-producing, anaerobic clostridium, strain P7T, was isolated from sediment from an agricultural settling lagoon after enrichment with CO as the substrate. The metabolism of this Gram-positive, motile, spore-forming rod was primarily acetogenic. Acetate, ethanol, butyrate and butanol were the end-products of metabolism. Strain P7T grew on CO, H2/CO2, glucose, galactose, fructose, xylose, mannose, cellobiose, trehalose, cellulose, starch, pectin, citrate, glycerol, ethanol, propanol, 2-propanol, butanol, glutamate, aspartate, alanine, histidine, asparagine, serine, betaine, choline and syringate as sole substrates. Growth was not supported by methanol, formate, d-arabinose, fucose, lactose, melibiose, amygdalin, gluconate, lactate, malate, arginine, glutamine or vanillate. Nitrate reduction, production of indole, gelatin hydrolysis and aesculin hydrolysis were not observed. Analysis of the 16S rRNA gene sequence of the isolate showed that it was closely related to Clostridium scatologenes ATCC 25775T (99·7 % sequence similarity) and clostridial strain SL1T (99·8 % sequence similarity). Strain SL1 had been classified as a strain of C. scatologenes. However, DNA–DNA reassociation analysis showed that both strain P7T and strain SL1 represented novel clostridial species. It is proposed that strain P7T (=ATCC BAA-624T=DSM 15243T) be classified as the type strain of Clostridium carboxidivorans sp. nov. and that strain SL1T (=ATCC BAA-623T=DSM 12750T) be reclassified as the type strain of Clostridium drakei sp. nov.

302 citations

Journal ArticleDOI
Abstract: The analysis of saccharides by liquid chromatography on an automated instrument is described. Conditions for the resolution and quantitation of fructose, glucose, sucrose, melibiose, raffinose, betaine and three kestose isomers as well as starch hydrolysates are given. Liquid chromatographic analysis equals the precision and accuracy of gas-liquid chromatographic analysis. Greater analysis flexibility and reduced sample preparation are important advantages over gas-liquid chromatographic analysis.

255 citations

Journal ArticleDOI
TL;DR: An 11-kilobase gene region of Streptococcus mutans has been identified which contains eight contiguous genes involved with the uptake and metabolism of multiple sugars (the msm system), and Insertional inactivation of each of these genes along with uptake data indicate that this system is responsible for the uptake of melibiose, raffinose, and isomaltotriose.
Abstract: An 11-kilobase gene region of Streptococcus mutans has been identified which contains eight contiguous genes involved with the uptake and metabolism of multiple sugars (the msm system). Sequence analysis of this region indicates that several of these genes specify proteins with strong homology to components of periplasmic binding protein-dependent transport systems of Gram-negative bacteria. Additionally, this operon is controlled by a regulatory gene (msmR) that acts as a positive effector. The proteins specified by the structural genes of the msm operon include alpha-galactosidase (aga), a "periplasmic-like" sugar-binding protein (msmE), two membrane proteins (msmF, msmG), sucrose phosphorylase (gtfA), an ATP-binding protein (msmK), and dextran glucosidase (dexB). Insertional inactivation of each of these genes along with uptake data indicate that this system is responsible for the uptake of melibiose, raffinose, and isomaltotriose and the metabolism of melibiose, sucrose, and isomaltosaccharides.

245 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20221
202112
202017
201913
201816
201715