Requirement of the core structure of a complex-type glycopeptide for the binding to immobilized lentil- and pea-lectins

Structural requirements for the binding of oligosaccharides and glycopeptides to immobilized lentil- and pea-lectins were investigated by use of radioactively-labeled glycopeptides and oligosaccharides. The results indicate that an intact 2- acetamido-2-deoxy-β-d-glucopyranosyl residue at the reducing end of a complex-type oligosaccharide is essential for high-affinity binding to lentil lectin-Sepharose but not to concanavalin A-Sepharose and that an asparagine residue is required for the binding of a complex-type glycopeptide to pea lectin-Sepharose. In addition, interaction of a complex-type oligosaccharide with lentil lectin-Sepharose was enhanced by exposure of nonreducing, terminal 2-acetamido-2-deoxy-β-d-glucopyranosyl groups, whereas interaction with pea lectin-Sepharose was enhanced only after exposure of nonreducing, terminal α-d-mannopyranosyl groups.     

Self-Nonself Recognition Activity Extracted from Self-Sterile Eggs of the Ascidian, Ciona intestinalis

Eggs of the hermaphrodite, self-sterile ascidian, Ciona intestinalis , were washed with acid seawater (pH 3.2), and the washing solution was then adjusted to pH 8.2. This solution was found to inhibit only the binding of non-autologous sperm to the vitelline coat (VC) of eggs, indicating that it contained self-nonself recognition activity. This activity was heat-stable and insensitive to trypsin, but was destroyed by V-8 protease and α-glucosidase. Both the hydrophobic and hydrophilic components of a lyophilized powder of the extract showed allo-recognizing activity. On TLC, the hydrophobic components gave a major spot of glucose (Glc) and a peptide spot(s) containing mainly glutamic acid and/or glutamine (Glx). The glucosyl conjugate was purified by HPLC and shown to block sperm-egg binding to various extents. Individual peptide subfractions had no inhibitory activity, but in combination they showed inhibitory activity. These findings suggest that the acid extract of Ciona eggs contains a Glc-enriched nonspecific inhibitor of sperm-egg binding, which could be the primary effector of self-incompatibility, and Glx-enriched modulators, which serve as acceptors of allo-sperm. The cooperative interactions of these components may be responsible for the diversity of allo-recognition in Ciona gametes.     

Identification and characterization of apolipoprotein(AII-E2-AII) complex in human plasma lipoprotein.

A new apolipoprotein complex designated as the apo(AII-E2-AII) complex was identified in the lipoprotein fractions of human plasma with apoE phenotypes containing apoE2 (E4/E2, E3/E2, and E2/E2). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by an immunoblotting assay using anti-apoE or anti-apoAII antibodies, established that the apo(AII-E2-AII) complex, with a molecular weight of 58,000, was identical to the complex consisting of apoE and apoAII, and that it also dissociated following reduction with beta-mercaptoethanol. This new complex was also demonstrated to be distinct from the apo(E-AII) complex and apoE monomer by isoelectric focusing, in the samples that were not treated with beta-mercaptoethanol. In apoE phenotype E3/E2, the apo(AII-E2-AII) complex was primarily included in the high-density lipoprotein (HDL, 1.063 < d < 1.21 g/ml) fraction, but was also observed in a small quantity in the very-low-density lipoprotein (VLDL, d < 1.006 g/ml) fraction. For further characterization, the apo(AII-E2-AII) complex was isolated by preparative SDS-PAGE, and no contamination of apo(E-AII) complex and apoE monomer was detected by immunoblotting assay using an anti-apoE antibody. It was confirmed by an enzyme-linked immunosorbent assay (ELISA) system that a molecular ratio between apoAII monomer and apoE in the isolated apo(AII-E2-AII) complex was approx. 2, when the apo(E-AII) complex was used as a standard with the ratio of 1:1. It indicates that the apo(AII-E2-AII) complex is formed from two molecules of apoAII monomer and one molecule of apoE.(ABSTRACT TRUNCATED AT 250 WORDS)     

ATPase activity of SopA, a protein essential for active partitioning of F plasmid

Summary The SopA, B, C genes of the F plasmid play an essential role in plasmid partitioning during cell division in Escherichia coli. In this paper, the products of the sopA and sopB genes were isolated and their biochemical activities studied. [-³²P]ATP was cross-linked to the SopA protein by UV irradiation; this cross-linking was observed only in the presence of magnesium ion, and was competitively inhibited in the presence of non-radioactive ATP, ADP and dATP, but not other NTPs or dNTPs. In contrast, no ATP binding activity was detected for the SopB protein. The SopA protein showed a modest magnesium ion-dependent ATPase activity and this activity was stimulated in the presence of DNA. The ATPase activity in the presence of DNA was further stimulated by addition of the SopB protein. However, the SopB protein alone failed to stimulate the ATPase activity.     

ATP-dependent strontium uptake by basolateral membrane vesicles from rat renal cortex in the absence or presence of calcium

ATP-dependent Sr²⁺ transport was examined in vitro using basolateral membrane (BLM) vesicles isolated from rat renal cortex to clarify the discrimination mechanisms between strontium (Sr) and calcium (Ca) in renal tubules during reabsorption. ATP-dependent Sr²⁺ uptake and Ca²⁺ uptake were observed in renal BLM vesicles and were inhibited by vanadate. Hill plots indicate similar kinetic behavior for Ca²⁺ and Sr²⁺ uptake. The apparentK _m andV _max of ATP-dependent Sr²⁺ uptake were both higher than those for Ca²⁺ uptake. ATP-dependent Sr²⁺ uptake by BLM vesicles diminished in the presence of 0.1 μM Ca²⁺ and was more markedly inhibited by 1 μM Ca²⁺. Hill plots of Sr²⁺ uptake data with and without 0.1 μM Ca²⁺ showed that the cooperative behavior of Sr²⁺ uptake was not changed by Ca²⁺. In the presence of 0.1 μM Ca²⁺, the affinity of the transport system for Sr²⁺ and the velocity of Sr²⁺ uptake in the BLM were both decreased. However, the rate of Ca²⁺ uptake was not diminished by Sr²⁺ concentrations of <1.6 μM. These results suggest that Ca²⁺ is preferentially transported in the renal cortex BLM when Ca²⁺ and Sr²⁺ are present at the same time.     

INTERACTIONS BETWEEN KURIL SEALS AND SALMON TRAP NET FISHERY IN THE COASTAL WATERS OF SOUTHEASTERN HOKKAIDO

An annual average of 163 Kuril seals was found dead in two years in salmon trap nets along the coastal waters of the Nemuro Peninsula and adjacent areas. The seal-caused damage to the total salmon catch at the salmon trap nets was concentrated in some of them, particularly No. 27, where seals killed or injured 5.1% of the catch in 1982, and 1.8% in 1983. Based on the proportion of Kuril seals among the dead seals in the trap nets, it was estimated that Kuril seals damaged 4.7% of the total salmon catch at No. 27 in 1982, and 1.7% in 1983. Not all seals that entered the trap net drowned; some killed or damaged salmon, and then escaped.     

A possible clinical application of multicytokine-producing cytotoxic mononuclear cell (MCCM) therapy

When peripheral blood mononuclear cells (PBMC) were incubated with a streptococcal preparation, OK-432, for 24 h, PBMC acquired cytolytic activity against cultured and fresh human tumor cells. Such PBMC were called OK-432-activated mononuclear cells (OK-MC). OK-MC produce several kinds of cytokines such as interferon (IFN), IFN, and tumor growth inhibitory factor (TGIF) bothin vitro andin vivo. OK-MC-produced cytokines also inhibited the growth of cultured and fresh human tumor cells. The growth inhibition was examined by human tumor clonogenic assay using a double-layer agar technique. The results indicate that two pathways of anti-tumor activity are induced in OK-MC, i.e., cell-mediated and cytokine-mediated.