Small intestinal differentiation in human colon carcinoma HT29 cells has distinct effects on the lateral diffusion of lipids (ganglioside GM1) and proteins (HLA class 1, HLA class 2, and neoplastic epithelial antigens) in the apical cell membrane

We have studied the effect of maturation to small intestinal-like epithelial cells of the human colonic carcinoma cell line HT29 on the lateral mobility of different representative membrane components (lipid, proteins), as assessed with fluorescence recovery after photobleaching (FRAP). Maturation was induced in vitro in the HT29 cells by replacing glucose (Glu) with galactose (Gal) in the growth medium (DMEM) during a 21-day period. Scanning electron microscopy revealed an increased number of microvilli in the apical cell membrane, and enzyme analyses (alkaline phosphatase, aminopeptidase) in combination with aqueous countercurrent distribution, indicated that maturation was induced with DMEM-Gal. In comparison to control cells grown in DMEM-Glu medium, the more small intestinal-like cells grown in DMEM-Gal displayed no alteration of the lateral mobility of either cholera toxin (B subunit)-labelled ganglioside GM1 (diffusion coefficient, D [x 10(8)] = 0.8-0.9 cm2s-1; mobile fraction, R = 50-60%) or antibody-stained Class 2 histocompatibility (HLA-DR) antigen (D [x 10(9)] = 2 cm2s-1; R = 60-70%). However, antibody-labelled beta 2-microglobulin of HLA Class 1 antigen displayed increased mobility in HT29-Gal cells; D was x 1.4 and R x 1.8 larger in the HT29-Gal cells. By contrast, the mobility of a neoplastic antigen was reduced; D and R were x0.60 and x0.69 of the values seen in HT29-Glu cells. It is thus concluded that DMEM-Gal-induced differentiation in confluent HT29 cells is accompanied by specific rather than general effects on the lateral mobility of different membrane components.     

Lectin histochemistry of mammalian Brunner's glands

Summary Lectin histochemical study was performed on twenty-eight specimens of formalin-fixed paraffin embedded tissues of proximal duodenum from human, cat, dog and Rhesus (macaque) monkey to demonstrate the pattern of carbohydrate residues in submucosal glands of Brunner as compared to that of the duodenal absorptive and goblet cells. Ten different biotinylated lectins were used as probes, and avidin-biotin-peroxidase (ABC) or avidin-gold-silver (AGS) complexes were used as visualants. Brunner's gland cells of the four species studied exhibited a similar lectin-binding pattern which differ from other duodenal cells. The epithelium of Brunner's gland stained intensely with Ricinus communis agglutinin-I (RCA-I), succinylated-WGA (S-WGA) and wheat-germ agglutinin (WGA), moderately with Bandeirea simplicifolia agglutinin-I (BS-I), Concanavalia ensiformis agglutinin (Con A) peanut agglutinin (PNA) and Ulex europaeus agglutinin-I (UEA-I) and occasionally with Dolichos biflorus agglutinin (DBA), Lens culinaris agglutinin (LCA) and soybean agglutinin (SBA). Desialylation with neuraminidase resulted in only a slight elevation in binding intensities of PNA, DBA and SBA, indicating that glycoconjugates of the Brunner's gland cells are rich in asialo-oligosaccharides, which differs from duodenal epithelial cells. In addition, these histochemical reagents were useful in localizing Brunner's gland elements in the duodenal mucosa.     

Lateral diffusion of plasma membrane receptors labelled with either platelet-derived growth factor (PDGF) or wheat germ agglutinin (WGA) in human polymorphonuclear leukocytes and fibroblasts

The aims of the present investigation were (a) to compare the lateral mobility of membrane receptors of human fibroblasts and polymorphonuclear leukocytes (PMNL) labelled with either platelet-derived growth factor (PDGF), or the lectin wheat germ agglutinin (WGA), and (b) to study effects of serum or PDGF on the mobility of these receptor molecules in human fibroblasts. Human foreskin fibroblasts (AG 1523) were grown on coverslips either under standard (10%) or under serum-free conditions yielding normal and starved cells, respectively. The receptor mobility was studied in response to exposure to PDGF, or serum, in short time or prolonged incubations. Human polymorphonuclear leukocytes (PMNL) were adhered to microscope slides by clotting drops of blood. They were stained with rhodaminated PDGF or fluoresceinated WGA. The diffusion of labelled receptors was assessed with fluorescence recovery after photobleaching (FRAP). It was found that (a) fibroblasts grown at normal serum concentration had a lower diffusion coefficient (D=3×10^–10 cm² s^–1) for the PDGF-receptor and a slightly lower mobile fraction (R=60%) than starved cells (D=5×10^–10 cm²s^–1 and R=73%), (b) addition of serum to starved cells increased both D and R for the PDGF receptor to 12×10^–10 cm² s^–1 and 96%, respectively, (c) a similar pattern was obtained for WGA-labelled glycoconjugates indicating general membrane effects of serum-induced cell stimulation, and (d) in PMNL the PDGF receptor displayed motility characteristics (D=3–4×10^–10 cm² s^–1 and R=59%) similar to those in fibroblasts, possibly suggesting equivalent anchorage mechanisms in the membrane.     

Enhancement of glycosylation of cellular glycoconjugates in the squamous carcinoma cell line MDA886Ln by β-all-trans retinoic acid

Retinoids have been shown to inhibit the growth and modulate the glycosylation of head and neck squamous cell carcinoma (HNSCC) cells including the MDA886Ln cells. To examine the effects of -all-trans retinoic acid (RA) on glycoconjugates in HNSCC MDA886Ln cells, the cells were grown in the absence or presence of 1 µM RA and then labeled with tritiated monosaccharides, extracted and analysed by polyacrylamide gel electrophoresis and fluorography. RA increased markedly the incorporation of [³H]-glucosamine, [³H]-galactose, and [³H]-mannose into numerous cellular glycoconjugates, however, the incorporation of [³H]-fucose and [³H]-leucine was almost unaffected by RA. RA increased the incorporation of glucosamine and galactose but not mannose into high molecular weight (HMW) glycoconjugates of about 220 and 500–600 kDa. To analyse the steady state level of glycoconjugates by lectin blotting, extracts of unlabeled cells were separated by gel electrophoresis and the gels were probed with¹²⁵I-labeled wheat germ agglutinin (WGA) andMaackia amurensis (MA) agglutinin. Both lectins were found to bind to numerous glycoconjugates including the HMW glycoconjugates, whereas¹²⁵I-peanut agglutinin bound only to the HMW glycoconjugates. RA treatment increased the binding of all three lectins to the HMW glycoconjugates. These findings demonstrate that RA enhanced the incorporation of specific monosaccharides into a variety of glycoconjugates and in particular into HMW mucin-like glycoconjugates. This effect of RA may be the result of induction of a more normal differentiation state of the HNSCC cells.     

Conformation of heparin studied with macromolecular hydrodynamic methods and X-ray scattering

The hydrodynamic characteristics of heparin fractions in a 0.2 M NaCl solution have been determined. Experimental values varied over the following ranges: the sedimentation coefficient (at 20.0 °C), 1.3<s₀×10¹³<3.2 s; the Gralen coefficient (sedimentation concentration-dependence parameter), 10<k_s<70 cm³ g^–1; the translational diffusion coefficient, 3.9<D₀×10⁷<15.4 cm² s^–1; the intrinsic viscosity, 7.9<[]<40 cm³ g^–1. Combination of s₀ with D₀ using the Svedberg equation yielded molecular weights in the range 3.9<M×10^–3<37 g mol^–1. The value of the mass per unit length of the heparin molecule, M_L, was determined using the theory of hydrodynamic properties of a weakly bending rod, giving M_L=570±50 g nm^–1 mol^–1. The equilibrium rigidity, Kuhn segment length (A=9±2 nm) and hydrodynamic diameter (d=0.9±0.1 nm) of heparin were evaluated on the basis of the worm-like coil theory without the excluded volume effect, using the combination of hydrodynamic data obtained from fractions of different sizes. Small-angle X-ray scattering for three heparin fractions allowed an estimate for the cross-sectional radius of gyration as 0.43 nm; from the evolution with the macromolecule contour length of the radius of gyration, a value for the Kuhn segment length of 9±1 nm was obtained. A good correlation is thus observed for the conformational parameters of heparin from hydrodynamic and X-ray scattering data. These values describe heparin as a semi-rigid polymer, with an equilibrium rigidity that is essentially determined by a structural component, the electrostatic contribution being negligible in 0.2 M NaCl.Presented at the conference for Advances in Analytical Ultracentrifugation and Hydrodynamics, 8–11 June 2002, Grenoble, France     

Carbohydrate exposure of human promyelocytic HL60 cells and histiocytic U937 cells during phagocytic differentiation assessed with fluoresceinated lectins

The display of carbohydrate structures was measured in promyelocytic HL60 cells and in histiocytic U937 cells induced to differentiate to phagocytic cellsin vitro during three to seven days of cultivation in the presence of dimethylsulfoxide (DMSO). It was assessed by micro-or spectrofluorometric quantification of the binding of fluorescent lectins. Changes in the cell size and the association and uptake of IgG-or complementopsonized yeast cells (Saccharomyces cerevisiae) were used as signs of phagocyte differentiation.The binding of wheat germ agglutinin (WGA), concanavalin A (Con A),Ricinus communis agglutinin-I (RCA-I) andUlex europaeus agglutinin-I (UEA-I) varied due to the presence of DMSO during cultivation, and without DMSO also on the number of days in culture and the type of cell.Abbreviations DMSO dimethylsulfoxide - PMA phorbol 12-myristate 13-acetate - KRG Krebs-Ringer phosphate buffer with glucose - WGA wheat germ agglutinin - Con A concanavalin A - RCA-I Ricinus communis agglutinin-I - UEA-I Ulex europaeus agglutinin-I     

Cytochemical localization of carbohydrates in intercalated duct and acinar cells of mouse parotid gland

Summary The glycoconjugate composition of mouse intercalated duct and acinar cells of parotid gland has been compared. Mucins containing 1,2-glycols were demonstrated by the tannic acid-uranyl acetate technique. Hexose residues of glycoconjugates were identified using ferritin conjugated withCanavalia ensiformis agglutinin (Con A),Triticum vulgare or wheat germ agglutinin (WGA),Ricinus communis I agglutinin (RCA-I),Phaseolus vulgaris agglutinin (PHA-E) andArachis hypogaea agglutinin (PNA). Whereas qualitative and quantitative differences were observed in sugar residues of secretory granules in intercalated duct and acinar cells, apical plasmalemmae were labelled sparsely and similarly. This indicates that the glycocalyx composition of apical plasma minae in the parotid acinar and intercalated duct cells is little influenced by secretory granule composition.     

Diffusion of sucrose in xanthan gum solutions

Molecular diffusion of solutes, like sucrose in the xanthan gum fermentation, is important in order to understand the complex behavior of mass transfer mechanisms during the process. This work was focused to determine the diffusion coefficient of sucrose, a carbon source for xanthan production, using similar sucrose and xanthan concentrations to those occurring in a typical fermentation. The diaphragm cell method was used in experimental determinations. The data showed that diffusion coefficient of sucrose significantly decreases when xanthan gum concentration increases. Theoretical and semiempirical models were used to predict sucrose diffusivity in xanthan solutions. Molecular properties and rheological behavior of the system were considered in the modeling. The models tested fitted well the behavior of experimental data and that reported for oxygen in the same system.List of Symbols A constant in eq. (5) - C _pg cm^–3 polymer concentration - D cm² s^–1 diffusivity - D _ABcm² s^–1 diffusivity of A through liquid solvent - D _APcm² s^–1 diffusivity of A in polymer solution - D _AWcm² s^–1 diffusivity of A in water - D _Pcm² s^–1 diffusivity of polymer in liquid solvent - E _D gradient of the activation energy for diffusion - H _P hydratation factor of the polymer in water (g of bound water/g of polymer) - K dyn sⁿ cm^–2 consistency index - K ₁ constant in eq. (5) - K _P overall binding coefficient [g of bound solute/cm³ of solution]/[g of free solute/cm³ of polymer free solution] - n flow behavior index - M _Bg g mol^–1 molucular weight of liquid solvent - M _Pg g mol^–1 molecular weight of the polymer - M _Sg g mol^–1 Molecular weight of polymer solution (= M _BX_B+M_PX_P) - R cm³ atm g mol^–1 K^–1 ideal gas law constant - T K absolute temperature - V _Bcm³ g mol^–1 molar volume of liquid solvent - V _Pcm³ g mol^–1 molar volume of polymer - V _Scm³ g mol^–1 molar volume of polymer solution - X _B solvent molar fraction - X _P polymer molar fraction - polymer blockage shape factor - _P volume fraction of polymer in polymer solution - g cm^–1 s^–1 viscosity - _ag cm^–1 s^–1 apparent viscosity of the polymer solution - _icm³ g^–1 intrinsic viscosity - ₀ g cm^–1 s^–1 solvent viscosity - _Pg cm^–1 s^–1 polymer solution viscosity - _R relative viscosity (= / ₀) - ₌₀ g cm^–1 s^–1 viscosity of polymer solution obtained at zero shear rate - ₀ g cm^–3 water density     

Wheat germ agglutinin binding sites on human urothelial cells of different grades of transformation

¹²⁵I-Wheat germ agglutinin (WGA) binding parameters of human urothelial cell lines of different grades of transformation (TGrll and TGrlll) were compared. The values of association constant (K_a) and the number of binding sites/cell for HCV29 (TGrll) cell line were about 3×10⁶M^–1 and over 4×10⁷, respectively. Two TGrlll cell lines, HCV29T and Hu549 revealed lower values for K_a, and considerably higher numbers of binding sites/cell (about 3×10⁸ and 2×10⁸, respectively). Binding of¹²⁵I-WGA to total cellular proteins resolved by SDS-PAGE and transferred to nitrocellulose showed multiple diffused bands in the range of 58–180 kDa. Some of these bands were characteristic for TGrll cells (124 kDa) or TGrlll cells (135 and 148 kDa).Abbreviations TGr transformation grade - WGA wheat germ agglutinin - sWGA succinylated wheat germ agglutinin - GlcNAc N-acetyl-d-glucosamine - BSA bovine serum albumin - SDS-PAGE sodium dodecyl sulphate polyacrylamide gel electrophoresis     

Membrane-bound glycoconjugates of fetal mouse erythropoietic cells with special reference to phagocytosis by hepatic macrophages

Using lectin and colloidal iron (CI) stainings in combination with neuraminidase digestion, glycoconjugates on the surface of erythropoietic cells of the yolk sac and liver in fetal mice were examined. Fetal hepatic macrophages were capable of distinguishing between phagocytozed and non-phagocytozed erythroid elements as described in our previous study. Marked differences between these two elements could be ultrahistochemically detected on their cell surface. The phagocytozed elements, such as nuclei expelled from erythroblasts and degenerating primitive erythroblasts, faintly bound neuraminidase-sensitive CI, and neuraminidase digestion imparted a weak peanut agglutinin (PNA) binding. In contrast, erythroblasts at various maturation stages, erythrocytes and normal primitive erythroblasts heavily bound neuraminidase-sensitive CI, and neuraminidase digestion imparted a moderate PNA binding. No differences in binding of either concanavalin agglutinin,Ricinus communis agglutinin-I or PNA were noted between phagocytozed and non-phagocytozed erythroid elements. Desialylation appears to be one of the most important signs for the recognition mechanism of fetal macrophage phagocytosis. During maturation of hepatic erythroblasts, sialic acid changes its affinity forLimax flavus agglutinin from strong to weak, and soybean agglutinin binding sites disappear at the basophilic erythroblast stage. Glycoconjugates on polychromatophilic erythroblasts acquire similar compositions to those of erythrocytes.     

Lectin histochemistry of mammalian Brunner's glands

Lectin histochemical study was performed on twenty-eight specimens of formalin-fixed paraffin embedded tissues of proximal duodenum from human, cat, dog and Rhesus (macaque) monkey to demonstrate the pattern of carbohydrate residues in submucosal glands of Brunner as compared to that of the duodenal absorptive and goblet cells. Ten different biotinylated lectins were used as probes, and avidin-biotin-peroxidase (ABC) or avidin-gold-silver (AGS) complexes were used as "visualants". Brunner's gland cells of the four species studied exhibited a similar lectin-binding pattern which differ from other duodenal cells. The epithelium of Brunner's gland stained intensely with Ricinus communis agglutinin-I (RCA-I), succinylated-WGA (S-WGA) and wheat-germ agglutinin (WGA), moderately with Bandeirea simplicifolia agglutinin-I (BS-I), Concanavalia ensiformis agglutinin (Con A) peanut agglutinin (PNA) and Ulex europaeus agglutinin-I (UEA-I) and occasionally with Dolichos biflorus agglutinin (DBA), Lens culinaris agglutinin (LCA) and soybean agglutinin (SBA). Desialylation with neuraminidase resulted in only a slight elevation in binding intensities of PNA, DBA and SBA, indicating that glycoconjugates of the Brunner's gland cells are rich in asialo-oligosaccharides, which differs from duodenal epithelial cells. In addition, these histochemical reagents were useful in localizing Brunner's gland elements in the duodenal mucosa.     

Lectin histochemistry of mammalian endothelium

Summary Lectin-histochemical studies were performed on formalin-fixed, paraffin-embedded tissues from ten mammalian species to demonstrate the pattern of carbohydrate residues in vascular endothelium. Ten different biotinylated lectins were used as probes and avidin-biotin-peroxidase complex (ABC) was used as visualant. Ricinus communis agglutinin-I (RCA-I) and wheat germ agglutinin (WGA) stained vascular endothelium in all species. Peanut agglutinin (PNA) stained vascular endothelium in all species only after preincubation with neuraminidase. Bandeirea simplicifolia agglutinin-I (BS-I) stained vascular endothelium in all species but human, while, Ulex europeus agglutinin-I (UEA-I) stained only human endothelium. Individual differences in staining of human vascular endothelium were noted with BS-I and succinylated-WGA (SWGA). Similarly, individual differences in staining of animal vascular endothelium were noted with soybean agglutinin (SBA) after preincubation with neuraminidase. Finally, Concanavalia ensiformis agglutinin (Con A), Dolichos biflorus agglutinin (DBA) and Lens culinaris agglutinin (LCA) did not stain vascular endothehuman in any of the species studied.     

Histone-induced conformational changes in DNA as probed by quasi-elastic light scattering.

Quasi-elastic light scattering as measured by intensity fluctuation (self-beat) spectroscopy in the time domain can be profitably used to follow both the translational diffusion D and the dominant internal flexing mode τ_int of DNA and its complexes with various histones in aqueous salt solutions. Without histones, DNA is found to have D = 1.6 × 10^?8 cm²/sec and τ_int ? 5 × 10^?4 sec in 0.8 M NaCl, 2 M urea at 20°C. Total histone as well as fraction F2A induce supercoiling (D = 2.6 × 10^?8 cm²/sec, τ_int ? 2.8 × 10^?4 sec) whereas fraction F1 induces uncoiling (D = 1.0 × 10^?8 cm²/sec, τ_int ? 9.4 × 10^?4 sec). Upon increasing the salt concentration to 1.5 M the DNA–histone complex dissociates (D = 1.8 × 10^?8 cm²/sec). Upon decreasing the salt concentration to far below 0.8 M, the DNA–histone complex eventually precipitates as a chromatin gel.     

Identification of fucosylated glycoconjugates in Xenopus laevis testis by lectin histochemistry

Glycoconjugates play roles in many physiological and pathological processes. Previous works have shown important functions mediated by glycans in spermatogenesis, and the carbohydrate composition of testis has been studied by several approaches, including lectin-histochemical methods. However, the testis of Xenopus laevis, an animal model extensively employed in biochemical, cell and developmental research, has not yet been analysed. The aim of this work was to carry out a histochemical study of the fucose (Fuc)-containing glycoconjugates of Xenopus testis by means of lectins, combined with deglycosylation pretreatments. Four Fuc-binding lectins were used: orange peel (Aleuria aurantia) lectin (AAL), gorse seed (Ulex europaeus) agglutinin-I (UEA-I), fresh water eel (Anguilla anguilla) agglutinin (AAA), and asparagus pea (Lotus tetragonolobus) agglutinin (LTA), each recognizing different forms of fucosylated glycans. Labelling with UEA-I, which preferably binds Fucα(1,2) containing oligosaccharides, did not show any appreciable staining. LTA, specific for Fucα(1,3), and AAA, which binds Fucα(1,2), labelled spermatocytes and spermatids, but no labelling was seen when the histochemical procedure was carried out after either β-elimination (which removes O-linked oligosaccharides) or incubation with PNGase F (which removes N-linked oligosaccharides), suggesting that fucosylated glycans are of both N- and O-linked types. AAL, which has its highest affinity to Fucα(1,6), but also recognizes Fucα(1,2) and Fucα(1,3), labelled the whole testis, and the staining remained when the histochemical method was performed after either β-elimination or incubation with PNGase F. Labelling with AAL could be explained by the fact that this lectin could be binding to diverse fucosylated glycans in N- and O-glycans, and even in glycolipids. The importance of these glycans is discussed.     

Glycoconjugate pattern of membranes in the acinar cell of the rat pancreas

Summary Lectin-binding studies were performed at the ultrastructural level to characterize glycoconjugate patterns on membrane systems in pancreatic acinar cells of the rat. Five lectins reacting with different sugar moieties were applied to ultrathin frozen sections: concanavalin A (ConA): glucose, mannose; wheat-germ agglutinin (WGA): N-acetylglucosamine, sialic acid; Ricinus communis agglutinin I (RCA I): galactose; Ulex europaeus agglutinin I (UEA I): l-fucose; soybean agglutinin (SBA): N-acetylgalactosamine). Binding sites of lectins were visualized either by direct conjugation to colloidal gold or by the use of a three-step procedure involving additional immune reactions. The rough endoplasmic reticulum and the nuclear envelope of acinar cells was selectively labelled for ConA. The membranes of the Golgi apparatus bound all lectins applied with an increasing intensity proceeding from the cis-to the trans-Golgi area for SBA, UEA I and WGA. In contrast RCA I selectively labelled the trans-Golgi cisternae. The membranes of condensing vacuoles and zymogen granules were labelled for all lectins used although the density of the label differed between the lectins. In contrast the content of zymogen granules failed to bind SBA and WGA. Lysosomal bodies (membranes and content) revealed binding sites for all lectins used. The plasma membranes were heavily labelled by all lectins except for SBA which showed only a weak binding to the lateral and the apical plasma membrane. These results are in accordance to current biochemical knowledge of the successive steps in the glycosylation of membrane proteins. It could be demonstrated, that the cryo-section technique is suitable for the fine structural localisation of surface glycoconjugates of plasma membranes and internal membranes in pancreatic acinar cells using plant lectins.     

Composition of soluble cuticular lipids and water permeability of cuticular membranes from Citrus leaves

Water permeability and composition of soluble cuticular lipids of isolated cuticular membranes from leaves of Citrus aurantium L. were investigated for 3 successive years. The average water permeability coefficient determined using 169 cuticular membranes was 1.09·10^–7 cm s^–1 with a standard deviation of 0.78·10^–7 cm s^–1. There were no significant differences in water permeability between years. Cuticular membranes are characterized by a great variability in water permeability both within and between years. Both water permeability of individual membranes and variability between membranes are shown to be determined by soluble cuticular lipids contained within the cuticular membranes. The soluble cuticular lipids of Citrus leaves are composed of fatty acids, primary alcohols, esters, and hydrocarbons. They occur in amounts of 9.84 g cm^–2, which represents approx. 3% of the total mass of isolated cuticular membranes. The specific weight of cuticular membranes (365.4 g cm^–1) and total amount of soluble cuticular lipids did not vary significantly between years. Significant differences were observed for the amounts and composition of the constituent classes of lipids. Six homologues comprise 86% of the fatty acids (C₁₆; C₁₈; C₁₉; C₂₁; C₂₄; C₂₆), 83% of the primary alcohols (C₂₄; C₂₆; C₂₈; C₃₀; C₃₂; C₃₄) and 88% of the esters (C₃₆; C₃₈; C₄₀; C₄₁; C₄₂; C₄₄). Eleven major homologues amount only to 62% of the total hydrocarbons (C₁₆; C₁₇; C₁₈; C₂₀; C₂₆; C₂₇; C₂₉; C₃₀; C₃₁; C₃₂; C₃₃). Variability in the composition of soluble cuticular lipids between years was much smaller than variability of water permeability and, therefore, no relation between composition of soluble cuticular lipids and water permeability could be found. It is suggested that this may be due to the fact that the lipid composition observed represents the averages of 20 to 30 membranes analyzed so that differences between individual membranes may have been leveled out.Abbreviations CM cuticular membranes - MX polymer matrix - P_d permeability coefficient for diffusion of water - SCL soluble cuticular lipids - MES morpholinoethane sulphonic acid     

Time course of vasopressin-induced formation of microvilli in granular cells of toad urinary bladder

Summary Vasopressin-induced transformation of ridges to microvilli on the surface of granular cells of toad urinary bladder occurs in conjunction with induced alterations in the water permeability of the luminal membrane. This study was designed to establish the relationship between the time course for induction of microvilli and the time course for induction of increased water permeability after vasopressin stimulation. Hemibladders were examined at 2.5, 5, 10, 20 and 30 min following exposure to 20 mU/ml of vasopressin and at 5, 10, 20, 30, 40, 50 and 60 min after washout of vasopressin. Within 2.5 min, vasopressin initiated complete transformation of ridges to microvilli on approximately 13% of the granular cells, while osmotic water flow (Jv) was 0.31±0.10 l·min^–1·cm^–2. Five minutes following vasopressin stimulation, microvilli were present on approximately 30% of granular cells andJv was 2.27±0.13 l·min^–1·cm^–2. At 10 minJv was maximum at 4.03±0.15 l·min^–1·cm^–2 and 50% of the granular cells were covered with microvilli. This percentage increased to 70% at 20 min and was maintained at 30 min, althoughJv decreased to 3.9±0.35 l·min^–1·cm^–2 at 30 min. Five minutes following vasopressin washout, ridges interspersed with microvilli reappeared asJv fell to 1.10±0.30 l·min^–1·cm^–2. At 10 min after vasopressin washout,Jv approached basal levels, but the reversal of microvilli to ridges remained incomplete. At 60 min after vasopressin washout, the granular cells had regained their original ridgelike surface structures. Thus, these studies establish a temporal relationship between the induction and reversibility of vasopressin-induced microvillous formation and alterations in the osmotic water permeability of the apical plasmalemma.     

Increased photosynthetic rates following gibberellic acid treatments to the roots of tomato plants

This study was conducted to evaluate the effects of root applications of gibberellic acid (GA₃) on photosynthesis in tomato plants grown hydroponically. Photosynthetic rates (mg CO₂/dm²/hr) determined using an open infrared CO₂ gas exchange system showed a 40–50% increase within 5 hr after treatment with a 1.4 µM gibberellic acid (GA₃) to their roots. The effect was shown to persist for the duration of the experiment (9 days). Plants receiving pulses of 1.4 µM GA₃ to the roots for 1, 4, 8 or 12 hr exhibited significantly higher photosynthetic rates than the control for 6 days following treatment. By day 9 however, there was no significant difference. Continual treatments with 1.4 µM GA₃ to the roots maintained the photosynthetic rate significantly higher than the control for the duration of the experiment. Interestingly, at the lower light levels the percent stimulation was more dramatic. There was approximately a 90% increase in the photosynthetic rate at 80 µE m^-2 s^-1 while at saturating light conditions (560 µE m^-2 s^-1) there was approximately a 40% increase over the control rate. The light saturation point for both treated and control plants was 240 µE m^-2 s^-1. Applications of physiologically relevant concentrations of GA₃ to the roots of tomato plants stimulates photosynthesis more consistently than that achieved by previous studies involving foliar absorption.Approved for publication on May 28, 1981 as paper number 6242 in the Journal series of the Pennsylvania Agricultural Experiment Station.     

Difference in the ability of blood group-specific lectins and monoclonal antibodies to recognize the ABH antigens in human tissues

Summary Twelve different kinds of blood group-specific lectins have been used along with monoclonal anti-A,-B and-H antibodies for detecting the corresponding antigens in selected human tissues. Although most of the lectins recognized the antigens in the tissue sections examined, they displayed marked differences in their recognition patterns in certain tissues.Helix asparsa agglutinin (HAA),Helix pomatia agglutinin (HPA) and monoclonal anti-A antibody recognized A antigens in the mucous cells of salivary glands from blood group A or AB nonsecretor as well as secretor individuals, whereasDolichos biflorus agglutinin (DBA).Griffonia simplicifolia agglutinin-I (GSA-I),Sophora japonica agglutinin (SJA) andVicia villosa agglutinin (VVA) did not bind to them from nonsecretors. A antigens in endothelial cells, lateral membrane of pancreatic acinar cells and small mucous-like cells of submandibular glands from some individuals were likewise recognized by HAA and HPA but not by other blood group A-specific lections. In contrast, both HAA and HPA did not recognize the A antigens in mucous cells of Brunner's glands while other A-specific lectins and monoclonal anti-A antibody reacted specifically with the antigens. Such a difference was not observed with lectins specific for blood group B. However, the B antigens in Brunner's glands were recognized by these lectins but not with monoclonal anti-B antibody. The difference in labelling ability was also noted among the blood group H-specific lectins and monoclonal anti-H antibody in endothelial cells of blood vessels.Ulex europaeus agglutinin-I reacted with these cells irrespective of ABO and the secretor status of the individuals, whileAnguilla anguilla agglutinin and monoclonal anti-H antibody reacted only with those cells from blood group O individuals. No reaction was observed withLotus tetragonolobus agglutinin in these tissue sites. These results suggest a great diversity of blood group antigens in different human tissues.     

Response of Photosynthetic Apparatus of Spring Barley (Hordeum vulgare L.) to Combined Effect of Elevated CO2 Concentration and Different Growth Irradiance

The response of barley (Hordeum vulgare L. cv. Akcent) to various photosynthetic photon flux densities (PPFDs) and elevated [CO₂] [700 μmol (CO₂) mol⁻¹; EC] was studied by gas exchange, chlorophyll (Chl) a fluorescence, and pigment analysis. In comparison with barley grown under ambient [CO₂] [350 μmol (CO₂) mol⁻¹; AC] the EC acclimation resulted in a decrease in photosynthetic capacity, reduced stomatal conductance, and decreased total Chl content. The extent of acclimation depression of photosynthesis, the most pronounced for the plants grown at 730 μmol m⁻² s⁻¹ (PPFD₇₃₀), may be related to the degree of sink-limitation. The increased non-radiative dissipation of absorbed photon energy for all EC plants corresponded to the higher de-epoxidation state of xanthophylls only for PPFD₇₃₀ barley. Further, a pronounced decrease in photosystem 2 (PS2) photochemical efficiency (given as F_V/F_M) for EC plants grown at 730 and 1 200 μmol m⁻² s⁻¹ in comparison with AC barley was related to the reduced epoxidation of antheraxanthin and zeaxanthin back to violaxanthin in darkness. Thus the EC conditions sensitise the photosynthetic apparatus of high-irradiance acclimated barley plants (particularly PPFD₇₃₀) to the photoinactivation of PS2. This revised version was published online in August 2006 with corrections to the Cover Date.