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.     

Location of O-acetyl groups in the acidic d-xylan of mimosa scabrella (bracatinga). A study of O-acetyl group migration

Extraction with dimethyl sulfoxide of wood-meal of the stem of bracatinga (Mimosa scabrella), a south Brazilian hardwood, that was defatted and delignified by treatment with aqueous chlorine at 0–5° followed by extraction with cold ethanol, gave a soluble O-acetylated 4-O-methyl-d-glucurono-d-xylan having (1→4)-linked β-d-xylopyranosyl residues that were unsubstituted (65%) and 2-O-(14%), 3-O- (16%), and 2,3-di-O-acetylated (5%), as determined by methylation analysis. Another preparation obtained by use of refluxing ethanol in the delignification process showed neither removal nor migration of acetyl groups. By comparison with synthetic, partly O-acetylated d-xylans of known composition, ¹³C-n.m.r. spectroscopy indicated that O-acetyl group migration does not occur during treatment with cold aqueous chlorine, refluxing ethanol, or water at 70°. Methyl 2-O-acetyl-4-O-methyl-β-d-xylopyranoside (6) was also unaffected by aqueous chlorine. O-Acetyl group migration took place more readily in aqueous and dimethyl sulfoxide solutions of 6 than of O-acetyl-d-xylans. The lowest temperatures at which migration was observed in monosaccharides was at 50 and 70° for solutions in D₂O and (CD₃)₂SO, respectively.     

Prostaglandin production by dispersed granulosa and theca interna cells from porcine preovulatory follicles

Prepubertal gilts were treated with 750 IU pregnant mares' serum gonadotropin (PMSG) and 72 h later with 500 IU human chorionic gonadotropin (hCG) to induce follicular growth and ovulation. Dispersed granulosa (GC) and theca interna (TIC) cells were prepared by microdissection and enzymatic digestion from follicles obtained 36, 72 and 108 h after PMSG treatment and incubated for up to 6 h in a chemically defined medium in the presence or absence of arachidonic acid, follicle-stimulating hormone (FSH), luteinizing hormone (LH) and indomethacin. Production of prostaglandin E2 (PGE) and prostaglandin F2 alpha (PGF) was measured by radioimmunoassay. Both GC and TIC had the capacity to produce prostaglandins, with production by each cell type increasing markedly with follicular maturation. PGE was the major prostaglandin produced by both cellular compartments. Only PGE production by GC was consistently enhanced by addition of arachidonic acid to the incubation medium. Neither cell type was responsive to FSH and LH in vitro. Indomethacin inhibited the production of PGE and PGF by both cell types. These results provide convincing evidence for an intrafollicular source of prostaglandins and indicate that both cellular compartments contribute significantly to the increased production of prostaglandins associated with follicular rupture.     

Nonvisual feeding in a visual planktivore,Xenomelaniris venezuelae

Summary Studies of the diel feeding patterns of the planktivorous fish, Xenomelaniris venezuelae, in Lake Valencia, Venezuela, revealed that, although the fish is primarily a diurnal feeder, it consumes substantial numbers of Chaoborus larvae and pupae at night. A number of fish species are known which feed on plankton at night, but these fish are filter feeders and their diets largely consist of relatively small, nonevasive prey. Chaoborus, however, is large and agile. Predation by Xenomelaniris in the dark was also studied experimentally. Captured fish were placed in completely darkened aquaria with zooplankton from Lake Valencia. After several hours the plankton was removed and examined for evidence of feeding. The fish were found to consume Chaoborus pupae and fourth instar larvae but not other types of prey. The mode of feeding by Xenomelaniris in the dark is unknown.     

Phospholipid-Sensitive Ca2+-Dependent Protein Kinase Preferentially Phosphorylates Serine-115 of Bovine Myelin Basic Protein

Phospholipid-sensitive Ca2+ -dependent protein kinase (PL-Ca-PK) and cyclic AMP-dependent protein kinase (A-PK) both preferentially phosphorylated serine residues of bovine myelin basic protein (MBP). Tryptic peptide maps of MBP phosphorylated by PL-Ca-PK or A-PK, however, revealed different phosphopeptides, suggesting a difference in the intramolecular substrate specificity for the two enzymes. Serine-115 of MBP, in the sequence (-Arg-Phe-Ser(115)-Trp-), was found to be a preferred and probably major phosphorylation site for PL-Ca-PK. Because serine-115 of bovine MBP corresponds to serine-113 of rabbit MBP, an in vivo phosphorylation site reported by Martenson et al. (1983), and PL-Ca-PK is present at a very high level in brain and myelin, it is suggested that the enzyme may be responsible for the in vivo phosphorylation of this and other sites in MBP.     

A novel method for the rapid cloning in Escherichia coli of Bacillus subtilis chromosomal DNA adjacent to Tn917 insertions

Summary A rapid and general procedure has been devised for the pBR322-mediated cloning in Escherichia coli of Bacillus subtilis chromosomal DNA extending in a specified direction from any Tn917 insertion. Derivatives of Tn917 have been constructed that contain a pBR322-derived replicon, together with a chloramphenicol-resistance (Cm^r) gene of Gram-positive origin (selectable in B. subtilis), inserted by ligation in two orientations into a SalI restriction site located near the center of the transposon. When linearized plasmid DNA carrying such derivatives was used to transform to Cm^r B. subtilis bacteria already containing a chromosomal insertion of Tn917, the pBR322 sequences efficiently became integrated into the chromosomal copy of the transposon by homologous recombination. It was then possible to clone chromosomal sequences adjacent to either transposon insertion junction into E. coli, using a selection for ampicillin-resistance, by transforming CaCl₂-treated cells with small amounts of insert-containing DNA that had been digested with various restriction enzymes and then ligated at a dilute concentration. Because pBR322 sequences may be inserted by recombination in either orientation with respect to the transposon arms, a single restriction enzyme (such as EcoRi or SphI) that has a unique recognition site in pBR322 DNA may be used to separately clone chromosomal DNA extending in either direction from the site of any transposon insertion. A family of clones generated from the region of an insertional spo mutation (spoIIH::Tn917) was used in Southern hybridization experiments to verify that cloned material isolated with this procedure accurately reflected the arrangement of sequences present in the chromosome. Strategies are discussed for taking advantage of certain properties inherent in the structure of clones generated in this way to facilitate the identification and study of promoters of insertionally mutated genes.     

An HLA-C-specific DNA probe

Analysis of available nucleotide sequence data for class I HLA genes has established that the seventh intron is one of the gene regions which expresses the highest degree of locus specificity (the percentage sequence divergence between nonallelic genes minus the percentage sequence divergence between allelic genes). We have subcloned short DNA sequences including this region from the HLA-Cw3 gene. Two clones, pC250 and pC800, were tested by hybridizing them at high stringency to a panel of clones containing class I HLA genes. Under conditions permitting a strong hybridization signal with a C-locus gene, pC800 also expressed a weak but significant hybridization to other class I genes, while pC250 appeared to hybridize exclusively to the C-locus gene. Hybridization of the pC250 probe at high stringency to Hind III-digested genomic DNA from a panel of unrelated individuals and homozygous typing cell lines revealed a single band in all cases. However, equivalent hybridization against Eco RI-digested DNA revealed two hybridization bands, one at 7.9 kb which correlated with the serologically defined Cw5 and Cw8 alleles, and one at 7.6 kb which correlated with the Cw1, Cw2, Cw3, Cw4, Cw6, and Cw7 alleles.     

Effects of CuDIPS and tween 80 on SJL/J tumorigenesis

Plasma copper and zinc levels were measured in SJL/J mice, an inbred strain characterized by a high, spontaneous incidence of reticulum cell sarcoma (RCS). The changes with age in mean concentrations of these metals were consistent with a physiological response that is required for remission of neoplasia. Treatment of SJL/J mice with a copper complex, Cu(II)(3,4-diisopropylsalicylate)₂ (Cu 3,5-DIPS), dissolved in a 10% Tween 80-saline solution revealed a decrease in survival and decline in the incidence of RCS at 52 wk of age. The toxic effects of Cu 3,5-DIPS therapy appeared to be related to the intraperitoneal route of administration and to extracellular deposition of collagen. The inhibitory effect on tumor development was not related to Cu 3,5-DIPS. Rather, Tween 80 was found to be the factor of importance.     

The influence of androgen administration on the structure and function of the brain-pituitary-gonad axis of sexually immature platyfish,Xiphophorus maculatus

Summary This report demonstrates that the administration of testosterone (T) or 11-ketotestosterone (11-KT) to sexually immature (8 wks old) male platyfish (Xiphophorus maculatus) of early-and late-maturing genotypes affects the synthesis and/or release of luteinizing hormone-releasing hormone (LHRH), as assessed by immunocytochemical evaluation, increases the number and activity of pituitary gonadotropes, stimulates the production of sperm and, thus, advances the age of sexual maturation over that dictated by the genome. We also show that 11-KT and T affect different LHRH-containing centers in the brain and have differential effects on rate and degree of sexual maturation, regardless of whether the hormones are administered to early or late-maturing genotypes.     

The daily timing of lamprey attacks

Synopsis Laboratory and field data suggest that several species of parasitic lampreys forage primarily at night, but data forPetromyzon marinus are equivocal. Nocturnal foraging may minimize predation risk. This may be particularly important to those species of lampreys that inhabit shallow streams. Nocturnal foraging also may enhance foraging efficiency if potential hosts at night are quiescent and more easily approached. Future experiments should be designed to avoid several potential sources of bias.