Coumarin and Euponin,Two Inhibitors for Insect Development from Leaves of Eupatorium japonicum

An ovicide and a larval growth inhibitor against Drosophila melanogaster were isolated from leaves of Eupatorium japonicum. The ovicide was identified as coumarin. The structure of the larval growth inhibitor, a new naturally occurring guaianolide named euponin, was elucidated on the basis of spectral and chemical evidence. The inhibitory effects of these agents on the egg and larva were also described.     

Sequence Analysis of a 32-kb Region Including the Major Ribosomal Protein Gene Clusters from Alkaliphilic Bacillus sp. Strain C-125

Forty-one open reading frames (ORFs) were identified in a 32-kb DNA fragment of alkaliphilic Bacillus sp. C-125. A similarity search using the BSORF database found 37 ORFs with significant sequence similarity to B. subtilis RNA polymerase subunits, elongation factor G, elongation factor Tu, and ribosomal proteins. Each ORF product showed more than 70% identity to those of B. subtilis. Gene organization in the region of str, S10, spc, and the α cluster was highly conserved among three strains, C-125, B. subtilis, and B. stearothermophilus.     

Peptide Presentation to T Cells: Solving the Immunogenic Puzzle

The vertebrate immune system uses an impressive arsenal of mechanisms to combat harmful cellular states such as infection. One way is via cells delivering real-time snapshots of their protein content to the cell surface in the form of short peptides. Specialized immune cells (T cells) sample these peptides and assess whether they are foreign, warranting an action such as destruction of the infected cell. The delivery of peptides to the cell surface is termed antigen processing and presentation, and decades of research have provided unprecedented understanding of this process. However, predicting the capacity for a given peptide to be immunogenic—to elicit a T cell response—has remained both enigmatic and a long sought-after goal. In the era of big data, a point is being approached where the steps of antigen processing and presentation can be quantified and assessed against peptide immunogenicity in order to build predictive models. This review presents new findings in this area and contemplates challenges ahead.     

Regiospecific orientation of single-chain antibody and atomic force microscope (AFM) images

An antibody containing a genetically engineered lipid group at the N-terminus and a hexahistidinyl tag at the C-terminus (Lpp-scFv-His6) was immobilized in an oriented manner on the surface of liposomes. Liposomes, consisting of antibody and phosphatidylcholine, have been prepared and imaged by AFM. For AFM visualization, the resulting liposomes were bound on the surface of mica by two different mechanisms. The histidine tags present in the antibody molecules of the immunoliposome were anchored to the NiCl₂ treated mica surface. Alternatively, the immunoliposomes were immunochemically bound on antigen-coated mica surface. Both approaches yielded liposomes which were clearly imaged without damage by AFM in ambient condition.     

Human glomerular basement membrane. Antigenic determinants in human urine

Antisera against particulate human glomerular basement membrane prepared from cadaver kidneys were raised in rabbits. It was shown that both normal individuals and patients with glomerular and tubular diseases excrete in their urine several antigens reactive with these antibodies. One antigen crossreacted immunologically with an antigen from human glomerular basement membrane while several others did not. One of the urinary antigens and the antigen crossreacting with the basement membrane were separated from the others by ion exchange chromatography and gel filtration, respectively.The pattern of antigen excretion differed depending on the underlying renal disease but the multitude of different antigens detected complicates the interpretation of the patterns of excretion in different diseases.     

Effects of glycerol on somatic embryogenesis in Cichorium leaves

 Direct somatic embryogenesis was induced in leaf cells of a Cichorium hybrid (Cichorium intybus L var. sativum×Cichorium endivia L. var. latifolia) through a two-step procedure. Leaf tissue explants were cultured for 5 days in M17 liquid medium supplemented with 30 mM sucrose and 330 mM glycerol (M17S30Gly330 medium). Synchronised divisions of embryogenic cells occurred after transfer for 7 days onto glycerol free-medium (M17S30). By doubling the sucrose concentration (60 mM) in the presence of glycerol (M17S60Gly330) during the induction step, embryogenesis increased and the length of the induction step was reduced from 5 to 4 days. Compared to sucrose, glycerol as carbon source during the induction and the expression steps had an inhibitory effect on the embryogenic response. During culture, glycerol was not detected in M17S60 medium and was at a low level in leaf fragments incubated in this medium. Initially supplied as an osmoticum, glycerol disappeared from M17S60Gly330 medium during the 4-day induction period and penetrated into the tissues where most of was metabolised. Furthermore, glycerol modified it carbohydrate metabolism, particularly during the induction period of embryogenesis. Sucrose hydrolysis was affected in the medium and sucrose and hexose contents in tissues were higher than in glycerol-free medium. The effects of glycerol as osmoticum and as a molecule itself are discussed. Received: 30 January 1998 / Accepted after revision 25 February 1999     

Purification and Preliminary Biochemical Characterisation of the Human and Rat Forms of the Central Nervous System-Specific Molecule, F3-87-8

The F3-87-8 monoclonal antibody recognises a phylogenetically conserved antigenic determinant found exclusively in the mammalian CNS. We used this monoclonal antibody as the major purification step for obtaining pure. F3-87-8-bearing molecules from rat and human brains for biochemical analysis. In both rat and man, the F3-87-8 molecule is a heavily glycosylated protein, consisting of 47.6 and 47.0% carbohydrate by weight, respectively. In both species, it occurs as a doublet on polyacrylamide gel electrophoresis in sodium dodecyl sulphate, the Mr of the human form being 130,000 and 100,000. In the rat, the Mr of the doublet is slightly but consistently lower than in man, and the higher-Mr band is more pronounced. The amino acid composition of the rat and human forms is virtually identical, with a high content of serine and threonine. Significant differences are seen in carbohydrate composition, the rat form containing more sialic acid and neutral sugar and less hexosamine than the human form. beta-Elimination studies, in conjunction with carbohydrate analysis, suggest the presence of approximately 40 O-linked and 10-15 N-linked oligosaccharides per polypeptide chain of 500 amino acids, the N-linked chains predominantly of the high-mannose type. This makes it likely that the molecule adopts an extended rather than a coiled conformation on the membrane.     

Monoclonal antibodies for the detection of desialylation of erythrocyte membranes during haemolytic disease and haemolytic uraemic syndrome caused by the in vivo action of microbial neuraminidase

Especially in childhood, the in vivo action of microbial neuraminidase may cause haemolytic anaemia or life-threatening haemolytic uraemic syndrome. The exposure of the Thomsen-Friedenreich (T) crypto-antigen and T-antigen polyagglutinability of erythrocytes has been described as the first sign of toxic cleavage of N-acetylneuraminic acid (Neu5Ac) from sialoglycoproteins of cell membranes. This phenomenon may, however, be too unspecific to initiate treatment for toxin elimination. The present study investigated the diagnostic effectiveness of a panel of three monoclonal antibodies (mcabs) for the estimation of the clinical significance of neuraminidase action in vivo. Depending on the amount of Neu5Ac released, the mcabs I-C4, II-Q9 and III-Y12 recognized different epitopes on erythrocyte asialoglycophorin. In 1345 patients, the mcab II-Q9 detected cleavage of Neu5Ac in 32 children who had T-antigen polyagglutinability and mild to moderate haemolytic anaemia. However, only 10 patients, whose erythrocytes were agglutinated by the mcabs III-Y12 or I-C4, developed severe haemolysis, thrombocytopenia, and finally the life-threatening haemolytic uraemic syndrome (p<0.0002). In conclusion, these mcabs provided an early marker of the in vivo action of neuraminidase. Two different degrees of erythrocyte desialylation, as defined by these mcabs, are suggested to reflect the severity of toxin-associated disease. This revised version was published online in November 2006 with corrections to the Cover Date.     

In Vivo-Like Antigenic Surface Properties of Staphylococcus aureus from Bovine Mastitis Induced upon Growth in Milk Whey

Antigenic surface properties of Staphylococcus aureus strains grown in milk whey were compared with TSB-grown bacteria using immuno-gold electron microscopy. It is shown that colloidal gold (CG) particles coated with polyclonal antibody raised against Staphylococcus aureus surface antigen expressed in vivo bound to the surface of S. aureus strain F1440 grown in milk whey, but not to homologous bacteria grown in TSB. S. aureus strains grown in milk whey agglutinated in the presence of the polyclonal antibody, whereas the corresponding bacteria grown in TSB did not agglutinate. Immuno-gold particles did not bind to milk whey-grown bacteria treated with periodate. Periodate-treated milk whey-grown bacteria did not agglutinate in the presence of the polyclonal antibody, whereas periodate treatment had no effect on TSB-grown bacteria.