Functional vasoactive intestinal polypeptide (VIP) receptors in human neuroblastoma subclones that contain VIP precursor mRNA and release VIP-like substances

Three phenotypically distinct subclones (SH-SY-5Y, SH-EP, SH-IN) of the human neuroblastoma cell line SK-N-SH were found to possess vasoactive intestinal polypeptide (VIP) precursor mRNA, release immunoreactive VIP, and express high-affinity VIP receptors coupled to adenylate cyclase. The apparent molecular mass for the receptor polypeptide, as determined by covalent cross-linking of 125I-VIP, was 49 kDa. After 2 days in culture, a concentration of immunoreactive VIP equivalent to the binding affinity of VIP to its receptor was found in the medium in two of these clones (SH-IN and SH-EP). Conditioned medium from SH-IN cells competitively displaced 125I-VIP binding and increased cAMP levels in SH-EP cells, indicating that all of the necessary components for a potential autocrine action of VIP exist in SK-N-SH cells. After numerous cell passages, the SH-EP subclone converted to a distinct phenotype in which VIP precursor mRNA and VIP immunoreactivity in the cell and medium were no longer detectable. In correlation, the VIP receptor number increased, and the EC50 for VIP stimulation of cAMP production shifted to a lower concentration. This points to the possibility that the continuous presence of endogenous VIP in earlier passage SH-EP cells causes a modification in VIP receptor number and cell responsiveness to VIP.     

Serotonin uptake and configurational change of bovine pulmonary artery smooth muscle cells in culture

Although it is well known that endothelial cells transport serotonin (5-HT) from extracellular to intracellular locations, it has been generally assumed that smooth muscle cells do not accumulate 5-HT but, rather, respond to 5-HT through a receptor activity unrelated to uptake of this amine or via stimulation of endothelial-derived relaxing factor. In the present study smooth muscle cells (PASMC), isolated and cultured from bovine pulmonary artery, were evaluated for 5-HT uptake under a variety of conditions. 5-HT uptake was linear up to 15 min and the rate was seven- to eightfold higher than that by bovine pulmonary artery endothelial cells. There was intracellular metabolism of 5-HT to 5-hydroxyindoleacetic acid (5-HIAA). The uptake was inhibited by exposure to 4 degrees C, absence of Na+ from the medium, and agents such as imipramine, verapamil, ketanserin, and methiothepin. Like that of endothelial cells, 5-HT uptake by PASMC was stimulated by exposure of cells to anoxia for 24 hr. Unlike endothelial cells that showed no morphological changes, PASMC at early passage showed dendritic formation after 30-60 min exposure to 5-HT at a concentration as low as 10(-8) M. Although this configurational change in response to 5-HT was lost with passage of cells, transport of 5-HT by these cells was retained. The configurational change was blocked by agents that inhibited 5-HT uptake, such as imipramine, verapamil, ketanserin, and methiothepin; it was unaffected by inhibitors of protein kinase C, phospholipase C, and calmodulin or absence of Ca2+ from the medium. We conclude that PASMC, as well as endothelial cells, accumulate 5-HT; there appears to be a close relationship between 5-HT uptake and configurational change of early passaged PASMC in culture. The factor(s) required for the configurational change are absent in endothelial cells and lost during passage of PASMC.     

Changes in vestibular postural response determined by information content of visual feedback

Electrical unipolar monoaural stimulation of the labyrinth led to body sway mainly on a frontal plane in normal human subjects in a standing position. Early and late stages of response with latencies of 120–200 and 200–500 msec respectively changing in size in accordance with conditions of visual control were distinguished in the stabilographic response. Maximum response was recorded when the eyes were closed. Response declined upon opening the eyes, fixing the gaze on a static target, and with visual feedback according to stabilograms. The early and late components declined by 10–20 and 50–70% respectively in all cases. Fixing the gaze, in darkness, on an illuminated light spot stationary in relation to the head had no effect on level of response. Once the expected direction of body sway had been imparted, a significant and almost identical decrease of 70–80% in both components took place with the gaze fixed, however. Early and late components of vestibulomotor response are thought to be mediated by regulatory mechasisms with differing time courses and functional connections.Institute of Research into Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vo. 22, No. 1, pp. 80–87, January–February, 1990.     

Morphological characteristics of callosal neurons of the cat primary auditory cortex (AI)

Cortical stratification of neurons forming callosal projections to the primary cortical area (AI) was investigated in cats using horseradish peroxidase axonal transport techniques. The population of area AI callosal neurons was found to be composed of several groups of cells. The group comprising around 60% of all callosal neurons of this area consists of large layer III pyramidal neurons. Callosal neurons belonging to this layer have a mean perikaryon profile area of 261.8±8.2 µm²; they account for 22% of all cells found in the layer. The second group, comprising 27% of all area AI callosal neurons, was largely made up of large layer V and VI cells; these could not be classed as pyramidal neurons due to the shape of their somata and the geometry of their dendritic arborization. Perikaryon profile in these nonpyramidal neurons occupied an area of 250.3±8.4 µ². No callosal neurons were observed in layer I. These account for 6 and 7% of total numbers of callosal neurons of area AI in layers II and IV. Callosal neurons were found to form projections to all layers of area AI in the contralateral hemisphere. Highest density of callosal fiber endings was observed in layers II and III.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 22, No. 2, pp. 249–256, March–April, 1990.     

Human antibodies react with an epitope of the human papillomavirus type 6b L1 open reading frame which is distinct from the type-common epitope.

Recombinant proteins encoded by the human papillomavirus type 6b (HPV6b) L1 open reading frame react with sera from patients with condylomata acuminata and also react with rabbit antiserum raised against sodium dodecyl sulfate-disrupted bovine papillomavirus type 1 (BPV1) virions. To map the immunoreactive epitopes, a series of procaryotic expression plasmids was made which contained a nested set of 3' to 5' deletions in the HPV6b L1 open reading frame. The deleted plasmids expressed a set of carboxy to amino terminus truncated fusion proteins. Regions containing the immunoreactive epitopes were mapped by determining which of the deleted fusion proteins retained reactivity with sera in Western immunoblot assays. The coding sequence for a human antibody-reactive linear epitope mapped between HPV6b nucleotide coordinates 7045 and 7087, and the rabbit anti-BPV1-reactive epitope coding sequence mapped between coordinates 6377 and 6454. Synthetic peptides derived from the epitope mapping were reacted with sera in enzyme-linked immunosorbent assay. Human sera reacted with synthetic peptide QSQAITCQKPTPEKEKPDPYK (HPV6b L1 amino acids 417 through 437). Rabbit anti-BPV1 and rabbit antisera raised against HPV16 L1 recombinant proteins reacted with the synthetic peptide DGDMVDTGFGAMNFADLQTNKSDVPIDI (HPV6b L1 amino acids 193 through 220). Human sera which reacted with HPV6b L1 fusion proteins cross-reacted with an HPV11 L1 fusion protein but did not react with fusion proteins encoded by HPV1a, HPV16, or HPV18. Rabbit anti-BPV1 reacted with L1 fusion proteins encoded by all of these HPV types. In contrast to the type-common (rabbit anti-BPV1-reactive) epitope, the human antibody-reactive epitope appears to be relatively HPV type specific.     

灯光诱虫在森林—鱼塘复合生态系统中的作用

昆虫是森林生态系统中的重要组成部分。由于森林中枯枝落叶较多,生境复杂,为昆虫提供了良好的繁殖和栖息场所;因而在森林中昆虫的种类多,数量大。大多数昆虫都以森林     

Scanning electron microscopy of cultures of rare macromycetous fungi

Using scanning electron microscopy it was possible to describe structures on the mycelia of macromycetous fungi that possess both taxonomic and functional importance. For taxonomic characteristization of 11 studied species, the presence and distribution of clamps on hyphæ represent an, important feature; in the case ofLyophyllum decastes the form of clamps may be useful for identifying cultures. Formation and types of anamorhps inPleurotus calyptratus, Montagnea arenaria andLyophyllum decastes are also of taxonomic importance. For additional taxonomic characterization of cultures ofTricholoma mongolicum the formation of “coils” might be exploited. Formation of anastomoses and crystals has predominantly a physiological role. However, in our view, production of crystals under certain culture conditions may serve as a diagnostic parameter.     

Utilization of Iron Sources and Its Possible Roles in the Pathogenesis of Vibrio parahaemolyticus

Vibrio parahaemolyticus is an important enteropathogen in Japan, Taiwan and other coastal regions. The influence of the regulation of iron on the pathogenesis of this pathogen has not been well characterized. The growth of pathogenic and non-pathogenic strains of V. parahaemolyticus on iron-limited agar plates was stimulated by ferritin, lactoferrin and transferrin at 30 μM , and also by hemin, hemoglobin and ferric ammonium citrate at 100 μM . Spontaneous iron-utilizing mutant strains (mutants) were derived from a clinical strain, ST550. Compared with the parent strain, lowered virulence was demonstrated for these mutants, as assayed by adult mouse and suckling mouse models. The in vivo growth and enterotoxigenicity of these mutants were also lower in the suckling mice. Adherence of the mutants to excised mouse intestine was lower as demonstrated by scanning electron microscopy. The iron-regulated outer membrane protein profile also changed in selected mutants. These results indicate that iron-regulated outer membrane proteins and other unknown factors associated with iron utilization may have profound influences, besides iron acquisition, on the pathogenesis of V. parahaemolyticus.     

Expression and localization of Lewisx glycolipids and GD1a ganglioside in human glioma cells

We analysed the glycolipid composition of glioma cells (N-370 FG cells), which are derived from a culture of transformed human fetal glial cells. The neutral and acidic glycolipid fractions were isolated by column chromatography on DEAE-Sephadex and analysed by high-performance thin-layer chromatography (HPTLC). The neutral glycolipid fraction contained 1.6 µg of lipid-bound glucose/galactose per mg protein and consisted of GlcCer (11.4% of total neutral glycolipids), GalCer (21.5%), LacCer (21.4%), Gb4 (21.1%), and three unknown neutral glycolipids (23%). These unknown glycolipids were characterized as Lewis^x (fucosylneolactonorpentaosyl ceramide; Le^x), difucosylneolactonorhexaosyl ceramide (dimeric Le^x), and neolactonorhexaosyl ceramide (nLc6) by an HPTLC-overlay method for glycolipids using specific mouse anti-glycolipid antibodies against glycolipid and/or liquid-secondary ion (LSI) mass spectrometry. The ganglioside fraction contained 0.6 µg of lipid-bound sialic acid per mg protein with GD1a as the predominant ganglioside species (83% of the total gangliosides) and GM3, GM2, and GM1 as minor components. Trace amounts of sialyl-Le^x and the complex type of sialyl-Le^x derivatives were also present. Immunocytochemical studies revealed that GD1a and GalCer were primarily localized on the surface of cell bodies. Interestingly, Le^x glycolipids and sialyl-Le^x were localized not only on the cell bodies but also on short cell processes. Especially, sialyl-Le^x glycolipid was located on the tip of fine cellular processes. The unique localization of the Le^x glycolipids suggests that they may be involved in cellular differentiation and initiation of cellular growth in this cell line.