There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

羟氨苄青霉素引起大疱性类天疱疮样疹

Isogenic strain construction and gene mapping in Candida albicans.

Lectins on cell surfaces mediate cell-cell interactions by combining with complementary carbohydrates on apposing cells. They play a key role in the control of various normal and pathological processes in living organisms.

http://science.sciencemag.org/content/sci/246/4927/227.full.pdf

Lectins as cell recognition molecules

/pdf/the-structure-biosynthesis-and-function-of-glycosylated-4rbegebbn2.pdf

The structure, biosynthesis and function of glycosylated phosphatidylinositols in the parasitic protozoa and higher eukaryotes.

The abundant surface glycolipid, promastigote lipophosphoglycan (LPG), of Leishmania promastigotes was isolated and reconstituted onto the surface of hydrophobic silica beads. These beads bound to both macrophages and monocytes, suggesting that phagocytes possess a receptor(s) capable of recognizing LPG. LPG beads were unable to bind to macrophages isolated from individuals with a genetic deficiency in the CD18 complex of leukocyte integrins (CR3, p150,95, and LFA-1), suggesting that one or more of these receptors were required for binding of LPG. Individual members of the CD18 complex were depleted from macrophages by plating cells on surfaces coated with anti-receptor mAb. These experiments indicated that CR3 and p150,95 from the CD18 complex, were the predominant mediators of attachment of LPG. The phagocyte receptor CR3 expresses two distinct binding sites, one that binds peptide ligands, such as C3bi, and a second site, that recognizes bacterial LPS. Antibody inhibition experiments and competition binding studies with synthetic peptides and soluble LPG indicated that LPG is recognized by the nonpeptide, or "LPS" binding site on CR3.

Lipophosphoglycan from Leishmania mexicana promastigotes binds to members of the CR3, p150,95 and LFA-1 family of leukocyte integrins.

Leishmania and the macrophage: a marriage of inconvenience.

Invasion of human tissues by the parasitic protozoan Entamoeba histolytica is a multistep process involving, as a first step, the recognition of surface molecules on target tissues by the amebas or trophozoites. This initial contact is followed by the release of proteolytic and other activities that lyse target cells and degrade the extracellular matrix. In other parasitic diseases, as well as in certain cancers, the interaction of invasive organisms or cells with fibronectin (FN) through specific receptors has been shown to be the initial step in target cell recognition. Interaction with FN triggers the release of proteolytic activities necessary for the effector cell migration and invasion. Here, we describe the specific interaction of Entamoeba histolytica trophozoites with FN, and identify a 37-kD membrane peptide as the putative receptor for FN. The interaction between the parasite and FN leads to a response reaction that includes the secretion of proteases that degrade the bound FN and the rearrangement of amebic actin into "adhesion plates" at sites of contact with FN-coated surfaces. The kinetics of the interaction was determined by measuring the binding of soluble 125I-FN to the trophozoites and visualization of the bound protein using specific antibodies. Degradation of FN was measured by gel electrophoresis and the release of radioactivity into the incubation medium. Focal degradation of FN was visualized as black spots under the trophozoites at contact sites with fluorescent FN. We conclude that the interaction of E. histolytica with FN occurs through a specific surface receptor. The interaction promotes amebic cytoskeleton changes and release of proteases from the parasite. The binding and degradation of extracellular matrix components may facilitate the migration and penetration of amebas into tissues, causing the lesions seen in human hosts.

/pdf/interaction-between-pathogenic-amebas-and-fibronectin-1j5c9ltixt.pdf

Interaction between pathogenic amebas and fibronectin: substrate degradation and changes in cytoskeleton organization.

A 220-kilodalton (kDa) protein with lectin properties was isolated from Entamoeba histolytica strain HM1:IMSS and was purified by Sepharose 4B chromatography and electroelution from 5% SDS-polyacrylamide gels. The protein contains 9% carbohydrate by weight; is rich in hydrophobic residues; and is very immunogenic in mice, hamsters, and rabbits. The protein binds to fixed monolayers of MDCK cells and inhibits trophozoite attachment to the cultured cells. The 220-kDa protein agglutinates human erythrocytes, and agglutination is inhibited by micromolar concentrations of hyaluronic acid, chitin, chitin-derived products (chitotriose), and antibodies to the purified protein. The 220-kDa protein is recognized by an antibody to the membrane but not by antibodies to other subcellular fractions. We therefore suggest that this 220-kDa protein with lectin properties is a component of the plasma membrane and could be one of the putative "receptor" molecules involved in cell and/or matrix attachment.

Patricia Talamás-Rohana

Papers

Lipophosphoglycan from Leishmania mexicana promastigotes binds to members of the CR3, p150,95 and LFA-1 family of leukocyte integrins.

Leishmania and the macrophage: a marriage of inconvenience.

Interaction between pathogenic amebas and fibronectin: substrate degradation and changes in cytoskeleton organization.

Isolation of a 220-Kilodalton Protein With Lectin Properties From a Virulent Strain of Entamoeba histolytica

The Cytoskeleton of Entamoeba histolytica: Structure, Function, and Regulation by Signaling Pathways