Increase in paratyphoid fever cases in Japanese travellers returning from Cambodia in 2013.

In 2013, an unusual increase of paratyphoid fever cases in travellers returning from Cambodia was reported in Japan. From December 2012 to September 2013, 18 cases of Salmonella Paratyphi A infection were identified. Microbiological analyses revealed that most isolates had the same clonal identity, although the epidemiological link between these cases remains unclear. It was inferred that the outbreak was caused by a common and persistent source in Cambodia that was likely to have continued during 2014. The information of surveillance and laboratory data from cases arising in travellers from countries with limited surveillance systems should be timely shared with the country of origin.

Macrophages control innate inflammation.

Macrophages play a critical role in the pathogenesis of metabolic diseases including gout and type 2 diabetes. The Nod-like receptor (NLR) family, pyrin domain containing 3 (NLRP3) forms the inflammasome with apoptosis-associated speck-like protein containing a CARD (ASC), the adaptor protein, and mediates inflammatory responses by macrophages. By compound screening, we found that tubulin polymerization inhibitors suppress NLRP3 inflammasome activation. NLRP3 inflammasome inducers reduce the NAD(+) level to inactivate the α-tubulin deacetylase Sirtuin 2, resulting in accumulation of acetylated α-tubulin. Acetylated α-tubulin mediates mitochondrial transport and subsequent proximity of ASC on mitochondria to NLRP3 on the endoplasmic reticulum. Thus, microtubule-driven transport of mitochondria is required for NLRP3 inflammasome activation. Macrophages are comprised of two subsets, M1 (inflammatory) and M2 (anti-inflammatory). Trib1 is an adaptor protein involved in protein degradation of immune-related transcription factors. We found that Trib1 is critical for the differentiation of F4/80(+) MR(+) tissue-resident M2-like macrophages. Mice lacking Trib1 in haematopoietic cells show severe lipodystrophy owing to increased lipolysis, even on a normal diet. In response to a high-fat diet, the mice show hypertriglyceridaemia and insulin resistance, together with increased proinflammatory cytokine production. Thus, Trib1 is critical for adipose tissue maintenance and suppression of metabolic disorders by controlling the differentiation of tissue-resident M2-like macrophages.

Molecular cloning, characterization of porcine IZUMO1, an IgSF family member.

IZUMO1, belonging to the family of mammalian immunoglobulin proteins, has been well characterized in the mouse. Here, we describe the molecular cloning and expression analysis of porcine IZUMO1 (pIZUMO1). Partial sequence information published in the National Center for Biotechnology Information (NCBI) database was used to generate the full-length sequence for IZUMO1 using rapid amplification of cDNA ends (RACE). A search of the porcine genomic sequence in the NCBI database identified a bacterial artificial chromosome (BAC) encoding the pIZUMO1 gene. This BAC is derived from porcine chromosome 6 and is syntenic with the corresponding regions of mouse, bovine, and human genomes encoding the IZUMO gene family. This BAC was found to encode an IZUMO1 protein with a predicted amino acid sequence having high similarity with mouse and human IZUMO1. Western blot analysis of proteins from porcine tissues indicated that pIZUMO1 was specifically expressed in the sperm. Furthermore, to confirm whether pIZUMO1 forms complexes, we overexpressed pIZUMO1 in HEK293 cells. The recombinant pIZUMO1 from cell extracts was found to form complexes. Our finding suggests that pIZUMO1 forms homodimeric complex on the sperm membrane. Furthermore, an IVF inhibition assay with an antibody for the porcine IZUMO1 Ig-like domain showed that Ig-like domain effectively prevented pig sperm-egg interactions.

Role of interleukin-17A in the eosinophil accumulation and mucosal remodeling in chronic rhinosinusitis with nasal polyps associated with asthma.

BACKGROUND: Interleukin (IL)-17A is a highly inflammatory cytokine with a robust effect on stromal cells in many tissues. Although IL-17A is known to be associated with inflammatory lung disorders by triggering an accumulation of neutrophils, the effect of IL-17A on the upper airway is still uncertain. The expression of IL-17A and its role were investigated in the nasal polyps of chronic rhinosinusitis associated with asthma. METHODS: IL-17A was detected by immunohistochemistry and quantitative real-time RT-PCR. The cellular source of IL-17A was examined by double staining with EG2, CD4 and neutrophil elastase. The tissue remodeling of the nasal polyps was evaluated by assessing the epithelial damage and basement membrane thickness. RESULTS: Both the immunoreactivity and mRNA of IL-17A were significantly detected in the nasal polyps in comparison with control normal sinus mucosa. The localization of IL-17A expression predominantly coincided with eosinophils and CD4-positive lymphocytes. Furthermore, the number of IL-17A-positive cells correlated with tissue eosinophils, but not with neutrophils. The degree of epithelial damage and basement membrane thickness was dependent on the number of infiltrated IL-17A-positive cells. CONCLUSION: The present study suggests, for the first time, that IL-17A plays an important role in the eosinophil accumulation in the nasal polyps and the remodeling of the nasal polyps of chronic rhinosinusitis associated with asthma.

Phosphorylation-dependent subcellular translocation of a Ca2+/calmodulin-dependent protein kinase produces an autonomous enzyme in Aplysia neurons.

We have shown previously that the subcellular distribution of a major calmodulin-binding protein is altered under conditions causing increased synthesis of cAMP in Aplysia neurons (Saitoh, T., and J. H. Schwartz, 1983, Proc. Natl. Acad. Sci. USA, 80:6708-6712). We now provide evidence that this Mr 55,000 protein is a subunit of a Ca2+/calmodulin-dependent kinase: (a) both the Mr 55,000 calmodulin-binding protein and kinase activity are loosely attached to the membrane-cytoskeletal complex; (b) both kinase activity and the Mr 55,000 protein are translocated from the membrane-cytoskeleton complex to the cytoplasm under conditions that cause the change in the subcellular distribution of the Mr 55,000 calmodulin-binding protein; and (c) calmodulin-binding activity of the Mr 55,000 protein and the ability to carry out the Ca2+/calmodulin-dependent phosphorylation of synapsin I are purified in parallel. The subcellular localization of the Ca2+/calmodulin-dependent protein kinase appears to be under control of two second messengers: Ca2+ and cAMP. We find that the Mr 55,000 subunit is phosphorylated when the extracted membrane-cytoskeleton complex is incubated with Ca2+, calmodulin, and ATP, with the concomitant release of this phosphorylated peptide from the complex. Previously, we had found that, when translocation occurs in extracts in the presence of cAMP and ATP (but in the absence of Ca2+), there was no detectable phosphorylation of the Mr 55,000 subunit itself. The subcellular distribution of the subunit thus appears to be influenced by (a) cAMP-dependent phosphorylation, which, we infer, modifies some as yet unidentified structural component, causing the release of the enzyme; and (b) Ca2+/calmodulin-dependent phosphorylation of the Mr 55,000 subunit. These studies also suggest that phosphorylation has an important regulatory consequence: during the Ca2+/calmodulin-dependent translocation of the Mr 55,000 subunit, the kinase appears to be activated, becoming independent of added Ca2+/calmodulin.

Amino acid sequence RERMS represents the active domain of amyloid beta/A4 protein precursor that promotes fibroblast growth.

The growth of A-1 fibroblasts depends on exogenous amyloid beta/A4 protein precursor (APP), providing a simple bioassay to study the function of APP. Our preliminary study, testing the activity of a series of fragments derived from the secreted form of APP-695 (sAPP-695) on this bioassay, has shown that at least one of the active sites of sAPP-695 was localized within a 40-mer sequence (APP296-335, Kang sequence; Roch, J.-M., I. P. Shapiro, M. P. Sundsmo, D. A. C. Otero, L. M. Refolo, N. K. Robakis, and T. Saitoh. 1992. J. Biol. Chem. 267:2214-2221). In the present study, to further characterize the growth-promoting activity of sAPP-695 on fibroblasts, we applied a battery of synthetic peptides on this bioassay and found that: (a) the sequence of five amino acids, RERMS (APP328-332), was uniquely required for the growth-promoting activity of sAPP-695; (b) the activity was sequence-specific because the reverse-sequence peptide of the active domain had no activity; and (c) the four-amino-acid peptide RMSQ (APP330-333), which partially overlaps the COOH-terminal side of the active sequence RERMS, could antagonize the activity of sAPP-695. Furthermore, a recombinant protein which lacks this active domain (APP20-591 without 306-335) did not promote fibroblast cell growth, suggesting that this domain is the only site of sAPP-695 involved in the growth stimulation. The availability of these biologically active, short peptides and their antagonists should prove to be an essential step for the elucidation of APP involvement in regulation of cellular homeostasis.

Monoclonal antibody 7H6 reacts with a novel tight junction-associated protein distinct from ZO-1, cingulin and ZO-2.

The tight junction is an essential element of the intercellular junctional complex; yet its protein composition is not fully understood. At present, only three proteins, ZO-1 (Stevenson, B. R., J. D. Siliciano, M. S. Mooseker, and D. A. Goodenough. 1986. J. Cell Biol. 103:755-766), cingulin (Citi, S., H. Sabanay, R. Jakes, B. Geiger, and J. Kendrick-Jones. 1988. Nature (Lond.). 333:272-275) and ZO-2 (Gumbiner, B., T. Lowenkopf, and D. Apatira. 1991. Proc. Natl. Acad. Sci. USA. 88:3460-3464) are known to be associated with the tight junction. We have generated a monoclonal antibody (7H6) against a bile canaliculus-rich membrane fraction prepared from rat liver. This 7H6 antigen was preferentially localized by immunofluorescence at the junctional complex regions of hepatocytes and other epithelia, and 7H6-affiliated gold particles were shown electron microscopically to localize at the periphery of tight junctions. Immunoblot analysis of a bile canaliculus-rich fraction of rat liver using 7H6, anti-ZO-1 antibody (R26.4C), and anti-cingulin antibody revealed that 7H6 reacted selectively with a 155-kD protein, whereas R26.4C reacted only with a 225-kD protein. Anti-cingulin antibody reacted solely with 140 and 108-kD proteins, indicating that the protein recognized by 7H6 is immunologically different from ZO-1 and cingulin. Immunoprecipitation of detergent extracts obtained from metabolically labeled MDCK cells with R26.4C coprecipitated a 160-kD protein, which corresponds to ZO-2, with ZO-1. However, 7H6 did not react with the 160-kD protein. These results strongly suggest that the 7H6 antibody recognizes a novel tight junction-associated protein different from ZO-1, cingulin and ZO-2.

Rejection of renal allografts: specific immunologic suppression.

Kidneys were transplanted across a major genetic barrier (Ag-B locus), from LewisxBN F(1) hybrid rats into bilaterally nephrectomized Lewis rats. Survival of grafts is prolonged (indefinite?) in rats treated with a combination of (i) intravenous injection of donor spleen cells 1 day before the graft, and (ii) passive immunization with antiserum prepared in rats of the recipient strain against donor spleen and lymph-node cells. The recipient's immune response to other antigens is not impaired.

Amyloid beta protein precursor is possibly a heparan sulfate proteoglycan core protein.

The amyloid beta protein peptide is a major constituent of amyloid plaque cores in Alzheimer's disease and is apparently derived from a higher molecular weight precursor. It is now shown that the core protein of a heparan sulfate proteoglycan secreted from a nerve cell line (PC12) has an amino acid sequence and a size very similar to those of the amyloid beta protein precursor and that these molecules are antigenically related. This amyloid beta protein precursor-related protein is not found in the conditioned medium of a variant cell line (F3 PC12) that does not secrete heparan sulfate proteoglycan. The synaptic localization and metabolism of this class of proteoglycans are consistent with its potential involvement in central nervous system dysfunction.

Relationship between epithelial damage or basement membrane thickness and eosinophilic infiltration in nasal polyps with chronic rhinosinusitis.

BACKGROUND: Chronic rhinosinusitis (CRS) with nasal polyps is characterized by eosinophilic infiltration. This study hypothesized that the aggregation of the mucosal pathology during remodeling is related to infiltrating eosinophils in patients with such nasal polyps. OBJECT: To clarify the pathogenetic role of eosinophils in patients with CRS with nasal polyps, this study investigated the relationship between epithelial damage or basement membrane (BM) thickening and the epithelial infiltration of eosinophils in these nasal polyps. METHODS: The number of eosinophils that infiltrated into the epithelial and subepithelial layers of sinonasal tissues was counted. The staging of epithelial damage allowed the quantification of epithelial loss. RESULTS: Both epithelial damage and BM thickness in CRS, which were correlated with the number of infiltrated eosinophils, were significantly greater than in the control group. Neither parameter showed significant differences between the asthma and non-asthma groups. There was a significantly correlation in the eosinophilic infiltration between the subepithelial and epithelial layers. CONCLUSION: It is suggested that eosinophils that infiltrate into both the epithelial and subepithelial layers play a part in the process of mucosal remodeling of CRS with nasal polyps.

The regulation of amyloid beta protein precursor secretion and its modulatory role in cell adhesion.

The regulation and function of two forms of the amyloid beta protein precursor (ABPP) that are released into the growth-conditioned medium of the PC12 nerve cell line were examined. Nerve growth factor increases the release of the form of ABPP without the protease-inhibitor domain relative to the protein containing the protease inhibitor and increases the overall rate of ABPP secretion 2-fold. In contrast, fibroblast growth factor increases the rate of ABPP secretion approximately 7-fold. Both forms of the secreted ABPP molecule are, in turn, able to stimulate adhesion of PC12 cells to substrata to which they are adsorbed about 10-fold more efficiently on a molar basis than Iaminin.

The precursor protein of non-A beta component of Alzheimer's disease amyloid is a presynaptic protein of the central nervous system.

Non-A beta component of Alzheimer's disease amyloid (NAC) is the second component in the amyloid from brain tissue of patients affected with Alzheimer's disease. Its precursor protein (NACP) was shown to be a brain-specific protein. In rat brain, NACP was more abundant in the neocortex, hippocampus, olfactory bulb, striatum, thalamus, and cerebellum and less abundant in the brain stem. Confocal laser microscopy analysis revealed that anti-NACP immunostaining was colocalized with synaptophysin-immunoreactive presynaptic terminals. Ultrastructural analysis showed that NACP immunoreactivity was associated with synaptic vesicles. NACP sequence showed 95% identity with that of rat synuclein 1, a synaptic/nuclear protein previously identified in rat brain, and good homology with Torpedo synuclein from the electric organ synapse and bovine phosphoneuroprotein 14 (PNP-14), a brain-specific protein present in synapses. Therefore, NACP is a synaptic protein, suggesting that synaptic aberration observed in senile plaques might be involved in amyloidogenesis in Alzheimer's disease.

Patterns of aberrant sprouting in Alzheimer's disease.

Alzheimer's disease (AD) is characterized by extensive synaptic and neuronal loss and by plaque formation in the cortex, but the mechanisms responsible for synaptic plasticity in the neocortex are still not completely understood. To analyze the sprouting response in AD cortex, we compared the patterns of GAP-43 with synaptophysin immunoreactivity. In AD, GAP-43 immunohistochemistry revealed extensive sprouting in the hippocampal molecular layer, stratum polymorphous, CA1 region, and prosubiculum. These regions presented abundant anti-GAP-43-immunoreactive coiled fibers and dystrophic neurites in association with plaques. Some of these sprouting structures were colocalized with anti-synapto-physin- and anti-neurofilament-positive neurites. The AD neocortex was characterized by an overall decrease in GAP-43 immunoreactivity accompanied by sprouting neurites in the areas of synaptic pathology. We conclude that GAP-43 might be involved in the mechanisms of synaptic plasticity in the AD cortex, as well as in the process of aberrant sprouting in the neuritic plaques.

Prognostic role of immunosuppressive acidic protein in patients with esophageal cancer.

Immunosuppressive acidic protein (IAP) suppresses several immune responses in vivo and in vitro , and high preoperative IAP levels could predict the impairment of the host's immunity. In this study prognostic significance of preoperative IAP levels was investigated in 68 esophageal cancer patients with curative resection and eight with non-curative resection. The curative group had significantly lower levels than the non-curative group (432 +/- 183 mg/mL vs. 739 +/- 235 mg/mL, P < 0.0001). The IAP levels were associated with T-status (P < 0.0001), lymphatic invasion (P < 0.05), and p-stages (P < 0.0001). When 5-year survival rate of patients with curative resection was compared by setting various cutoff values of IAP between high and low IAP groups, several cutoff points (400-580 mg/mL) were revealed to be significantly associated with survival. Setting cutoff value of IAP to 560 mg/mL resulted in a most significant difference of 5-year survival rate of patients between the high and low IAP groups (13.9% and 61.5%, P < 0.0001). These data indicate that pre-operative IAP level is a useful parameter to predict the prognosis of esophageal cancer patients after curative resection.

Adenine excisional repair function of MYH protein on the adenine:8-hydroxyguanine base pair in double-stranded DNA.

Adenine paired with 8-hydroxyguanine (oh(8)G), a major component of oxidative DNA damage, is excised by MYH base excision repair protein in human cells. Since repair activity of MYH protein on an A:G mismatch has also been reported, we compared the repair activity of His(6)-tagged MYH proteins, expressed in Spodoptera frugiperda Sf21 cells, on A:oh(8)G and A:G mismatches by DNA cleavage assay and gel mobility shift assay. We also compared the repair ability of type 1 mitochondrial protein with type 2 nuclear protein, as well as of polymorphic type 1-Q(324) and 2-Q(310) proteins with type 1-H(324) and 2-H(310) proteins by DNA cleavage assay and complementation assay of an Escherichia coli mutM mutY strain. In a reaction buffer with a low salt (0-50 mM) concentration, adenine DNA glycosylase activity of type 2 protein was detected on both A:oh(8)G and A:G substrates. However, in a reaction buffer with a 150 mM salt concentration, similar to physiological conditions, the glycosylase activity on A:G, but not on A:oh(8)G, was extremely reduced and the binding activity of type 2 protein for A:G, but not for A:oh(8)G, was proportionally reduced. The glycosylase activity on A:oh(8)G and the ability to suppress spontaneous mutagenesis were greater for type 2 than type 1 enzyme. There was apparently no difference in the repair activities between the two types of polymorphic MYH proteins. These results indicate that human MYH protein specifically catalyzes the glycosylase reaction on A:oh(8)G under physiological salt concentrations.

Quasi-particles ultrafastly releasing kink bosons to form Fermi arcs in a cuprate superconductor.

In a conventional framework, superconductivity is lost at a critical temperature (Tc) because, at higher temperatures, gluing bosons can no longer bind two electrons into a Cooper pair. In high-Tc cuprates, it is still unknown how superconductivity vanishes at Tc. We provide evidence that the so-called ≲ 70-meV kink bosons that dress the quasi-particle excitations are playing a key role in the loss of superconductivity in a cuprate. We irradiated a 170-fs laser pulse on Bi2Sr2CaCu2O(8+δ) and monitored the responses of the superconducting gap and dressed quasi-particles by time- and angle-resolved photoemission spectroscopy. We observe an ultrafast loss of superconducting gap near the d-wave node, or light-induced Fermi arcs, which is accompanied by spectral broadenings and weight redistributions occurring within the kink binding energy. We discuss that the underlying mechanism of the spectral broadening that induce the Fermi arc is the undressing of quasi-particles from the kink bosons. The loss mechanism is beyond the conventional framework, and can accept the unconventional phenomena such as the signatures of Cooper pairs remaining at temperatures above Tc.

Inhibitory effect of very-long-chain monounsaturated fatty-acyl-CoAs on the elongation of long-chain fatty acid in swine cerebral microsomes.

Characteristics of condensation and overall elongation of very-long-chain fatty-acyl-CoAs in swine cerebral microsomes were studied using radio high-performance liquid chromatography (RHPLC) and gas chromatography-mass spectrometry (GC-MS). The monounsaturated fatty-acyl-CoA depressed both the condensation and overall elongation activities of endogenous substrates and also of exogenous saturated fatty-acyl-CoA. The extent of the decrease of the elongation activity was dependent on the concentration and the chain length of the exogenous fatty-acyl-CoAs. The dependence of the condensation activity of monounsaturated fatty-acyl-CoA on the concentration of malonyl-CoA suggested that the non-Michaelis-Menten type kinetics was dominant for oleoyl-CoA, however, a normal kinetic pattern was obtained for endogenous palmitoyl-CoA and arachidonoyl-CoA with Km = 37 microM to malonyl-CoA. The condensation activity for icosanoyl-CoA (20:0-CoA) was inhibited by icosenoyl-CoA (20:1-CoA) in a non-competitive manner, which suggested that the condensation enzyme, or at least the active center of the enzyme for icosenoyl-CoA, was different from that for icosanoyl-CoA.

Hydrogen transfer by NADPH-dependent reductases in elongation of very-long-chain saturated and polyunsaturated fatty-acyl-CoA in swine cerebral microsomes.

The hydrogen transfer from NADPH was studied in the elongation of arachidoyl-CoA (20:0-CoA) and arachidonoyl-CoA (20:4-CoA) in swine cerebral microsomes. Previously, we showed that four deuterium atoms (2H) were transferred stereospecifically from (4S)-[4-2H1]NADPH in the elongation of 20:0-CoA to 24:0 (Yoshida, S., Takeshita, M. and Kawaguchi, A. (1984) Biochem. Biophys. Res. Commun. 124, 322-328), and that three deuterium atoms were transferred from 2H2O in the elongation of 20:4-CoA to 22:4. The deuteride transfer from (4S)-[4-2H1]NADPH was observed in the elongation of 20:4-CoA to 24:4, by the technique of mass fragmentography using the chemical ionization method, and, in this case, two 2H were transferred to 24:4. No deuteride was transferred from (4R)-[4-2H1]NADPH in the elongation of 20:0-CoA and 20:4-CoA. Moreover, the condensation product (3-keto-fatty-acyl-CoA) which was formed in the elongation without NADPH could be reduced by the addition of NADPH and sodium hydrosulfite, for the elongation of 16:0-CoA and 20:4-CoA, while the condensation product from 20:0-CoA could be reduced only by NADPH, but not by hydrosulfite. The hydrosulfite did not produce the final elongation products from 20:0-CoA, 16:0-CoA or 20:4-CoA. These results suggested that the hydride was transferred from NADPH stereospecifically only in the elongation of 20:0-CoA in the step of 3-ketoacyl-CoA reduction by the reductase which might be different from that for the elongation of 16:0-CoA and 20:4-CoA in which the proton exchange might occur via a water proton in the reduction of 3-ketoacyl-CoA. Accordingly, the hydride transfer might occur from NADPH in the step of 2,3-enoyl reduction in the elongation of 20:0-, 16:0- and 20:4-CoA.

Effect of phospholipase A2 and free fatty acids on lipid-protein interactions in long- and very-long-chain fatty acyl-CoA elongation enzyme systems of brain microsomes.

The elucidation of the mechanism of phospholipase A2-induced inactivation of the condensation enzyme provided evidence concerning the important role of lipid-enzyme interactions in maintaining the condensation activity in swine cerebral microsomes. A quantitative analysis of fatty acid release by phospholipase A2 from the microsomal membrane revealed that only 5 nmol of free fatty acid per mg microsomal protein was released, including oleic acid and arachidonic acid, by treatment with 0.4 unit of phospholipase A2 per mg microsomal protein for 15 s at 23 degrees C. Under these conditions, the condensation activity for endogenous 16:0-CoA and 20:4-CoA decreased to half and that for exogenous 20:0-CoA decreased to 75%. However, the addition of free fatty acids and lysophospholipids or a mixture of them at 5-10 nmol/mg protein did not change the condensation activity for endogenous 16:0-CoA and 20:4-CoA, or for exogenous 20:0-CoA. These results indicated that phospholipase A2 inhibited the condensation activity by acting directly on phospholipids that are indispensable to maintaining the function of the condensation enzyme. The Arrhenius plot for the condensation of endogenous 16:0-CoA showed a break at around 16 degrees C, whereas no break of the plot was observed for the condensation of 20:0-CoA and 20:4-CoA. The activation energy for the condensation of 16:0-CoA and 20:4-CoA was decreased by the addition of free fatty acids such as oleic acid and stearic acid, with disappearance of the Arrhenius break for 16:0-CoA condensation, whereas the activation energy for the condensation of 20:0-CoA was not changed. These results suggest that the type of lipid-protein interaction in the condensation enzyme for 20:0-CoA is different from that for 16:0-CoA and 20:4-CoA.

Visualization of exocytotic secretory processes of mast cells by fluorescence techniques.

Secretory processes via exocytosis in rat peritoneal mast cells were visualized by two complementary fluorescence techniques; one staining pre-exocytotic granules with a basic probe and the other staining post-exocytotic granules with acidic probes. Granules within mast cells were selectively stained with acridine orange and emitted orange yellow fluorescence. Upon stimulation with compound 48/80, release of acridine orange from granules was observed both in population and single cell measurements. This release was seen in some localized area of mast cells. Opening of pores between plasma membranes and granule membranes was monitored using acidic fluorescence probes such as 6-carboxyfluorescein or lucifer yellow CH. Not only granules located at peripheral region, but also granules near the core region participated in exocytosis. The existence of junctions between these granules was suggested. TMA-DPH, a lipophilic membrane probe, which was localized at plasma membrane before stimulation, diffused into granule membranes after stimulation. This shows that after stimulation, some constituents of plasma and granule membranes were mixed. Even after extensive degranulation, mast cells extruded acidic probes, indicating the plasma membranes still play a role of barrier. Activation of lateral motion of granules preceding to exocytosis was not observed. It was concluded that the visualization of secretory processes by fluorescence and image processing techniques will be useful for the study of molecular mechanisms underlying exocytosis.