Lectin-induced modulation of the antibody response to type III pneumococcal polysaccharide

Several lectins were tested for their capacity to alter the antibody response to type III pneumococcal polysaccharide (SSS-III). The antibody response was enhanced by concanavalin A (Con A), phytohemagglutinin (PHA), as well as lectins from Phytolacca americana (Pa-2), Pisum sativum (PSA), and Lens culinaris (LCH), when these lectins were given 2 days after immunization with SSS-III; however, suppression was obtained when Con A and Pa-2 were given at the time of immunization. By contrast the lectins from Vicia villosa (VVL) and Bauhinia purpurea (BPA) did not alter the antibody response. Since the lectins PSA and LCH bind to the same monosaccharide as Con A, whereas the other lectins bind to different monosaccharides, these findings indicate that there is no relationship between nominal monosaccharide specificity and the capacity to modulate the antibody response. Substantial increases in the magnitude of the IgG₁ antibody response was noted after the administration of Con A whereas profound enhancement of IgG_2a antibody response was noted after PHA was given.     

Bovine conglutinin is a collagen-like protein

Conglutinin is a bovine plasma protein which is relatively large and asymmetric with elevated contents of glycine and, to some extent, proline. Although its physiologic function is unknown, conglutinin is known to bind, in the presence of calcium, to yeast cell walls and to the solid-phase-inactivated third component of complement. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions, isolated conglutinin appeared to consist of a single polypeptide chain (Mr 48 000). Unreduced conglutinin consisted of a single stained band with an apparent molecular weight of approximately 300 000. Cross-linking experiments with glutaraldehyde and dimethyl suberimidate suggested that this Mr 300 000 molecule consists of six of the disulfide-linked polypeptide chains. Amino acid composition revealed hydroxylysine and hydroxyproline together with elevated glycine and proline contents. Digestion of reduced, alkylated conglutinin with bacterial collagenase resulted in formation of a precipitate which consisted of an Mr 24 000 peptide which was digested to Mr 21 000 with large quantities of collagenase. These peptides contained less glycine, proline, hydroxylysine, and hydroxyproline than did the intact protein. The supernatant from this digestion mixture was, however, enriched in these four amino acids, with glycine making up nearly one-third of the total. Prolonged digestion with pepsin at 37 degrees C resulted in an Mr 20 000 peptide which was enriched in glycine, proline, hydroxyproline, and hydroxylysine. Amino-terminal sequence analysis showed that the glycine-X-Y repeating sequence begins at residue 26.(ABSTRACT TRUNCATED AT 250 WORDS)     

Apparent increases in phospholipid degradation and turnover during combined treatment with protein synthesis inhibitors and adrenocorticotropin

Inhibitors of protein synthesis, cycloheximide and puromycin, blocked ACTH (adrenocorticotropin)-induced increases in phospholipid mass, including phosphatidylinositol, but paradoxically increase 32P-labelling (but not [3H]glycerol-labelling) therein. Cycloheximide also provoked an initial rapid decrease in 32P-prelabelled phospholipids, followed by an increase in [32P]Pi incorporation. These effects of cycloheximide and puromycin occurred in ACTH-treated (but not in control) cells. It appears that inhibition of protein synthesis during ACTH action provokes an increase in phospholipid degradation, followed by partial resynthesis of the phospholipid head groups.     

Location of a structural gene for xylose-H+ symport at 91 min on the linkage map of Escherichia coli K12

Mutations in the xylose-H+ transport activity of Escherichia coli K12 were isolated using Mud(ApRlac). The initial selection was for simultaneous acquisition of ampicillin and xylose resistance in an fda background. Colonies were then screened for xylose-inducible beta-galactosidase and for growth on xylose of their fda+ derivatives. Two of the xylose-positive derivatives were shown to be impaired in xylose-H+ symport in whole cells and in xylose transport into subcellular vesicles. Their xylose transport in whole cells showed increased sensitivity to arsenate. The site of prophage insertion was mapped to 91.4 min on the E. coli genome between pgi and malB. It is proposed that the gene for the xylose-H+ symport system be called xylE.     

Some factors involved in the dissolution of Autographa californica nuclear polyhedrosis virus polyhedra by digestive fluids of Trichoplusia ni larvae

Factors involved in the dissolution of polyhedra of Autographa californica nuclear polyhedrosis virus (AcNPV) by digestive fluid collected from fifth stage Trichoplusia ni larvae were studied in vitro. Observations were made at timed intervals using phase contrast microscopy and transmission electron microscopy. When digestive fluid was heated at 50°C proteases retained activity. Exposure of polyhedra to digestive fluid previously heated to 50°C resulted in polyhedral matrix dissolution and envelope disruption in a manner similar to that of unheated digestive fluid, only delayed slightly. After exposure of polyhedra for 3 min, only enveloped virons were observed. Heating the digestive fluid to 60° or higher inactivated the proteases and altered the effect on polyhedra. Dissolution of the occlusion body matrix occurred but the polyhedral envelope remained and only a few weakened areas were observed in its structure. Within the polyhedral envelope, enveloped virons were not observed, only nucleocapsids and capsids. Exposure of polyhedra to 0.1 m sodium carbonate buffer at pHs of 9.5 or higher had effects similar to those of the digestive fluid with heat (60°C)-inactivated proteases. The addition of trypsin and chymotrypsin to the 0.1 m sodium carbonate buffer had no effect, while the addition of a bacterial protease (Streptomyces griseus) at pHs of 9.5 or higher resulted in dissolution of the matrix and disruption of the polyhedral envelope like the digestive fluid. Material infectious to TN-368 cells was obtained by exposure of AcNPV to T. ni digestive fluid. Maximum infectivity resulted from a 5-min exposure to unheated digestive fluid, with a dramatic decrease in infectivity with longer exposure. Exposure to digestive fluid with heat (60°C)-inactivated proteases resulted in a slower release of infectious material from the occlusion body, with a steady increase in the level of infectivity throughout the 30-min digestion period.     

Use of dextran and post-primary antibody fixation in immunoperoxidase staining of fresh frozen tissue. Detection of immunoglobulin associated with squamous carcinomas of the head and neck

Use of unfixed fresh frozen tissue sections for immunocytochemical studies reduces the possibility of denaturation of antigenic determinants compared to formalin fixation and paraffin embedding procedures. However, tissue and cellular morphology can be extensively altered in the numerous application and washing steps with frozen tissue sections. We tested a number of buffer solutions and showed that the use of dextran-containing buffers and fixation by glutaraldehyde after primary antibody application preserves tissue morphology. The procedures described here are also applicable to ascertaining the presence of Fc receptors of leukocytes in sections of carcinoma tissues. The buffered dextran washes and post-primary antibody fixation method was used to demonstrate the presence of immunoglobulin associated with squamous carcinoma cells. The immunoglobulin was not removed by washing of tissue sections at 37 degrees C but could be removed by low or high pH buffer washes, suggesting that the immunoglobulin is bound in a specific manner.     

Cord blood plasma lipoproteins inhibit mitogen-stimulated lymphocyte proliferation

Lipoproteins were isolated from adult plasma and the umbilical cord blood plasma of newborn infants and were compared for their capacity to inhibit mitogen-stimulated [3H]thymidine uptake of adult peripheral blood mononuclear cells in vitro. Relative to the comparable adult lipoproteins, cord blood low density lipoproteins and high density lipoproteins inhibited mitogen stimulation at twofold to fourfold lower total protein concentrations. Apoproteins AI, B, and E were quantitated by radioimmunoassay of each of the adult and cord blood lipoprotein fractions. A strong correlation was observed between inhibitory activity and the amount of apoprotein E in the cord blood low and high density lipoproteins. Further evidence that lipoproteins containing apoprotein E accounted for the difference in suppressive activity of cord blood low and high density lipoproteins relative to the adult lipoproteins was obtained by selective removal of the apoprotein E-containing lipoproteins by using immunoaffinity chromatography or heparin-agarose adsorption. The results indicated that cord blood lipoproteins containing apoprotein E in association with apoproteins AI or B are capable of suppressing lymphocyte proliferation in vitro.     

Lymphatic endothelial celline (CH3) from a recurrent retroperitoneal lymphangioma

Summary An endothelial cell line derived from a massive recurrent chyle-containing retroperitoneal lymphangioma was isolated in monolayer culture. Scanning and transmission electron microscopy and immunohistochemistry confirmed a close resemblance to blood vascular endothelium with typical cobblestone morphology, positive immunofluorescence staining for endothelial marker Factor VIII-associated antigen and fibronectin, and prominent Weibel-Palade bodies. The endothelial cells also exhibited other ultrastructural features characteristic of lymphatic endothelium, including sparse microvillous surface projections, overlapping intercellular junctions, and abundant intermediate filaments. This endothelial cell line represents a new source of proliferating lymphatic endothelium for future study, including structural and functional comparison to blood vascular endothelium. Supported in part by Arizona Disease Control Research Commission contracts 8277-000000-1-1-AT-6625 and ZB-7492. Presented in part at the 10th International Congress of Lymphology in Adelaide, Australia, August 1985.     

Studies of human achondroplasia: oxidative metabolism in tissue culture cells

Mitochondria prepared from the first growth of cells (fibroblasts) from skin biopsies from homozygous (but not heterozygous) achondroplastic human subjects were unable to carry out oxidative phosphorylation. However, successive crops of cells gained the ability to phosphorylate with normal P:O ratios with pyruvate-malate and succinate as substrates. Concentrations of cytochromes a + a3 were markedly and significantly lower in homogenates of homozygous achondroplastic tissue culture cells than in homogenates of normal cells. Levels of cytochromes a + a3 in the heterozygous achondroplastic cells were intermediate between the levels in normal cells and the homozygous achondroplastic cells. Activities of the mitochondrial oxidative systems (NADH, succinic and cytochrome oxidases) were not significantly lower in the achondroplastic cell preparations than in normal cell preparations under standard assay conditions (saturation levels of oxygen).     

Several biotic and abiotic elicitors act synergistically in the induction of phytoalexin accumulation in soybean

Summary Plants often respond to microbial infection by producing antimicrobial compounds called phytoalexins. Plants also produce phytoalexins in response to in vitro treatment with molecules called elicitors. Specific elicitors, including a hexa--glucosyl glucitol derived from fungal cell walls, the pectin-degrading enzyme endopolygalacturonic acid lyase, and oligogalacturonides obtained by either partial acid hydrolysis or enzymatic degradation of plant cell walls or citrus polygalacturonic acid, induce soybean (Glycine max. L.) cytoledons to accumulate phytoalexins. The experiments reported here demonstrate that the elicitor-active hexa--glucosyl glucitol acts synergistically with several biotic and abiotic elicitors in the induction of phytoalexins in soybean cotyledons. At concentrations below 50 ng/ml, the hexa--glucosyl glucitol does not induce significant phytoalexin accumulation. When assayed in combination with either endopolygalacturonic acid lyase or with a decagalacturonide released from citrus polygalacturonic acid by this lyase, however, the observed elicitor activity of the hexa--glucosyl glucitol is as much as 35-fold higher than the sum of the responses of these elicitors assayed separately. A similar synergism was also demonstrated for the combination of the hexa--glucosyl glucitol with dilute solutions of sodium acetate, sodium formate, or sodium propionate buffers. These buffers are thought to damage or kill plant cells, which may cause the release of oligogalacturonides from the plant cell wall. The results suggest that oligogalacturonides act as signals of tissue damage and, as such, can enhance the response of plant tissues to other elicitor-active molecules during the initiation of phytoalexin accumulation.Supported by the United States Department of Energy DE-ACO2-84ER13161. This paper is number XXXI in a series, Host-Pathogen Interactions. The preceding paper, Host-Pathogen Interactions XXX is Characterization of elicitors of phytoalexin accumulation in soybean released from soybean cells by endopolygalacturonic acid lyase, by K. R. Davis, A. G. Darvill, P. Albersheim, and A. Dell. Zeitschrift für Naturforsschung, in press.