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1.
Kunio Koshimura Yasutaka Takagi Soichi Miwa †Tsuneo Kido ‡Yasuyoshi Watanabe Yoshio Murakami Yuzuru Kato Tomoh Masaki 《Journal of neurochemistry》1995,65(2):827-830
Abstract: 6R-l -erythro-Tetrahydrobiopterin (6R-BH4) is a cofactor for aromatic l -amino acid hydroxylases and nitric oxide synthase. Recently, we have reported that independently of its cofactor activities, 6R-BH4 acts from the outside of neurons in the brain to enhance the release of monoamine neurotransmitters such as dopamine. To characterize the pharmacological properties of the action, we examined the effects of 6S-BH4, a diastereoisomer of 6R-BH4, on dopamine release in the rat striatum by using brain microdialysis and compared its effects with those of 6R-BH4. Perfusion of 6S-BH4 or 6R-BH4 through the dialysis probe increased extracellular dopamine levels (an index of in vivo dopamine release) concentration dependently; the maximal increase by 6S-BH4, was one-sixth of that by 6R-BH4. 6S-BH4 increased extracellular DOPA levels in the presence of NSD 1015, an inhibitor of aromatic l -amino acid decarboxylase (an index of in vivo tyrosine hydroxylase activity), to an extent similar to the increase induced by 6R-BH4. The increase in the DOPA levels induced by either of the pteridines was abolished after pretreatment of rats with α-methyl-p-tyrosine (an inhibitor of tyrosine hydroxylase). Under the same conditions, the 6S-BH4-induced dopamine release was abolished, but most of the 6R-BH4-induced increase persisted. Coadministration of 6S-BH4 with 6R-BH4 inhibited the increase in dopamine release induced by 6R-BH4 alone. These results show that 6R-BH4 stimulates dopamine release by acting at the specific recognition site on the neuronal membrane, and that 6S-BH4 acts as an antagonist of 6R-BH4 at this site, although it has cofactor activities. 相似文献
2.
Ken Lee Akihiro Ito †Kunio Koshimura †Tetsuya Ohue †Yasutaka Takagi †Soichi Miwa 《Journal of neurochemistry》1995,64(2):874-882
Abstract: Hypoxia is known to disturb neuronal signal transmission at the synapse. Presynaptically, hypoxia is reported to suppress the release of neurotransmitters, but its postsynaptic effects, especially on the function of neurotransmitter receptors, have not yet been elucidated. To clarify the postsynaptic effects, we used cultured bovine adrenal chromaffin cells as a model of postsynaptic neurons and examined specific binding of l -[3 H]nicotine (an agonist for nicotinic acetylcholine receptors: nAChRs) and 22 Na+ flux under control and hypoxic conditions. Experiments were performed in media preequilibrated with a gas mixture of either 21% O2 /79% N2 (control) or 100% N2 (hypoxia). Scatchard analysis of the specific binding to the cells revealed that the KD under hypoxic conditions was twice as large as that under control conditions, whereas the B max was unchanged. When the specific [3 H]nicotine binding was kinetically analyzed, the association constant ( k 1 ) but not the dissociation constant ( k −1 ) was decreased to 40% of the control value by hypoxia. When the binding assay was performed using the membrane fraction, these changes were not observed. Nicotine-evoked 22 Na+ flux into the cells was suppressed by hypoxia. In contrast, specific [3 H]quinuclidinyl benzilate binding to the intact cells was unaffected by hypoxia. These results demonstrate that hypoxia specifically suppresses the function of nAChRs (and hence, neuronal signal transmission through nAChRs), primarily by acting intracellularly. 相似文献
3.
Takashi Sakamoto Akio Kobori Masako Shigezawa Yasutaka Amitani Maiko Higuchi Akira Murakami 《Nucleosides, nucleotides & nucleic acids》2013,32(10-12):1659-1664
We developed a bispyrene-conjugated 2 ′-O-methyloligoribonucleotide as an RNA-specific RNA-probe. The probe hybridized with the complementary RNA, greatly enhancing fluorescence and discriminating RNA from DNA. The assay was carried out in homogeneous aqueous media without removing the unbound probe from the detection solution. This homogeneous fluorescence assay also discriminated mismatch sequences in the target RNA. These pyrene probes could possess high potential to detect RNA in biological specimens simply. 相似文献
4.
Mark I. Melhorn Abigail S. Brodsky Jessica Estanislau Joseph A. Khoory Ben Illigens Itaru Hamachi Yasutaka Kurishita Andrew D. Fraser Anne Nicholson-Weller Elena Dolmatova Heather S. Duffy Ionita C. Ghiran 《The Journal of biological chemistry》2013,288(43):31139-31153
Humans and other higher primates are unique among mammals in using complement receptor 1 (CR1, CD35) on red blood cells (RBC) to ligate complement-tagged inflammatory particles (immune complexes, apoptotic/necrotic debris, and microbes) in the circulation for quiet transport to the sinusoids of spleen and liver where resident macrophages remove the particles, but allow the RBC to return unharmed to the circulation. This process is called immune-adherence clearance. In this study we found using luminometric- and fluorescence-based methods that ligation of CR1 on human RBC promotes ATP release. Our data show that CR1-mediated ATP release does not depend on Ca2+ or enzymes previously shown to mediate an increase in membrane deformability promoted by CR1 ligation. Furthermore, ATP release following CR1 ligation increases the mobility of the lipid fraction of RBC membranes, which in turn facilitates CR1 clustering, and thereby enhances the binding avidity of complement-opsonized particles to the RBC CR1. Finally, we have found that RBC-derived ATP has a stimulatory effect on phagocytosis of immune-adherent immune complexes. 相似文献
5.
We visualized flavonol distribution in the abaxial epidermis of onion scales without chemical processes via detection of blue-light-induced green autofluorescence. Our visualizing results indicated an unequal intercellular distribution of flavonols among epidermal cells causing a patch distribution in the epidermis, and indicated that flavonol accumulation in ultraviolet irradiated-onion scales was in uniformity with epidermal cells, probably to compensate for their stress-hypersensitiveness. 相似文献
6.
Joseph Khoory Jessica Estanislau Abdallah Elkhal Asmae Lazaar Mark I. Melhorn Abigail Brodsky Ben Illigens Itaru Hamachi Yasutaka Kurishita Alexander R. Ivanov Sergey Shevkoplyas Nathan I. Shapiro Ionita C. Ghiran 《PloS one》2016,11(1)
Acute, inflammatory conditions associated with dysregulated complement activation are characterized by significant increases in blood concentration of reactive oxygen species (ROS) and ATP. The mechanisms by which these molecules arise are not fully understood. In this study, using luminometric- and fluorescence-based methods, we show that ligation of glycophorin A (GPA) on human red blood cells (RBCs) results in a 2.1-fold, NADPH-oxidase-dependent increase in intracellular ROS that, in turn, trigger multiple downstream cascades leading to caspase-3 activation, ATP release, and increased band 3 phosphorylation. Functionally, using 2D microchannels to assess membrane deformability, GPS-ligated RBCs travel 33% slower than control RBCs, and lipid mobility was hindered by 10% using fluorescence recovery after photobleaching (FRAP). These outcomes were preventable by pretreating RBCs with cell-permeable ROS scavenger glutathione monoethyl ester (GSH-ME). Our results obtained in vitro using anti-GPA antibodies were validated using complement-altered RBCs isolated from control and septic patients. Our results suggest that during inflammatory conditions, circulating RBCs significantly contribute to capillary flow dysfunctions, and constitute an important but overlooked source of intravascular ROS and ATP, both critical mediators responsible for endothelial cell activation, microcirculation impairment, platelet activation, as well as long-term dysregulated adaptive and innate immune responses. 相似文献
7.
With more than 40,000 species, Malacostraca is the most diverse crustacean class. Most malacostracans are gonochoristic, but simultaneous hermaphrodites are also known. Tanaidacea is one of two malacostracan orders that includes simultaneously hermaphroditic species; so far, simultaneous hermaphroditism has been confirmed externally and internally in only two tanaidacean species, both in the genus Apseudes (Apseudidae). Here we show, through external and internal morphological observations of fixed specimens, that the apseudid Falsapseudes bowmani is a simultaneous hermaphrodite, making Falsapseudes the second tanaidacean genus in which simultaneous hermaphroditism has been confirmed both externally and internally. In this species, the epistome (a projection on the clypeus) was thick and elongate in large specimens but was thin and spiniform in smaller specimens; the brooding of eggs or embryos was observed only in thin‐epistome individuals, although a pair of ovaries was confirmed in both thick‐ and thin‐epistome individuals. This suggests that individuals with a thick epistome may act as males while also retaining the female reproductive organs. 相似文献
8.
Kitayama K Hayashida Y Nishida K Akama TO 《The Journal of biological chemistry》2007,282(41):30085-30096
Keratan sulfate glycosaminoglycans are among the most abundant carbohydrate components of the cornea and are suggested to play an important role in maintaining corneal extracellular matrix structure. Keratan sulfate carbohydrate chains consist of repeating N-acetyllactosamine disaccharides with sulfation on the 6-O positions of N-acetylglucosamine and galactose. Despite its importance for corneal function, the biosynthetic pathway of the carbohydrate chain and particularly the elongation steps are poorly understood. Here we analyzed enzymatic activity of two glycosyltransferases, beta1,3-N-acetylglucosaminyltansferase-7 (beta3GnT7) and beta1,4-galactosyltransferase-4 (beta4GalT4), in the production of keratan sulfate carbohydrate in vitro. These glycosyltransferases produced only short, elongated carbohydrates when they were reacted with substrate in the absence of a carbohydrate sulfotransferase; however, they produced extended GlcNAc-sulfated poly-N-acetyllactosamine structures with more than four repeats of the GlcNAc-sulfated N-acetyllactosamine unit in the presence of corneal N-acetylglucosamine 6-O sulfotransferase (CGn6ST). Moreover, we detected production of highly sulfated keratan sulfate by a two-step reaction in vitro with a mixture of beta3GnT7/beta4GalT4/CGn6ST followed by keratan sulfate galactose 6-O sulfotransferase treatment. We also observed that production of highly sulfated keratan sulfate in cultured human corneal epithelial cells was dramatically reduced when expression of beta3GnT7 or beta4GalT4 was suppressed by small interfering RNAs, indicating that these glycosyltransferases are responsible for elongation of the keratan sulfate carbohydrate backbone. 相似文献
9.
Differential Expression and Internal Feedback Regulation
of
1-Aminocyclopropane-1-Carboxylate Synthase,
1-Aminocyclopropane-1-Carboxylate Oxidase, and
Ethylene Receptor
Genes in Tomato Fruit during Development and Ripening 总被引:21,自引:1,他引:21 下载免费PDF全文
10.
Multianalyte immunoassay with self-assembled addressable microparticle array on a chip 总被引:1,自引:0,他引:1
This paper describes the random fluidic self-assembly of metallic particles into addressable two-dimensional microarrays and the use of these arrays as a platform for constructing a biochip useful for bioassays. The basic units in the assembly were the microfabricated particles carrying a straightforward visible code and the corresponding array template patterned on a glass substrate. The particles consisted of a hydrophobic and magnetic Ni-polytetrafluoroethylene (PTFE) composite layer on one face, and on the other face a gold layer that was modified for biomolecular attachment. An array template was photoresist-patterned with spatially discrete microwells in which an electrodeposited Ni-PTFE hydrophobic composite layer and a hydrophobic photo-adhesive coating were deposited. The particles, after biomaterial attachment and binding processes in bulk, were self-assembled randomly onto the lubricated bonding sites on the chip substrate, driven by a combination of magnetic, hydrophobic, and capillary interactions. The encoding symbol carried by the particles was used as the signature for the identification of each target/assay attached to the particle surface. We demonstrate here the utility of microfabricated-encoded particle arrays for conducting multianalyte immunoassays in a parallel fashion with the use of imaging detection. 相似文献