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41.
Protoplasts prepared from suspension-cultured Vinca rosea cellswere cultured for 5 days. The cell walls regenerated from theprotoplasts were mainly composed of glucans having 1,3- and1,4-linkages. To investigate the molecular species, these glucanswere separated into four fractions: EDTA (50 mM, pH 4.5)-soluble(fraction E), KOH (24%)- soluble but not precipitatable by neutralizationwith acetic acid (fraction K-S), KOH (24%)-soluble and precipitatableby neutralization with acetic acid (fraction K-P), and KOH (24%)-insoluble(fraction C). By means of sugar composition analysis, methylationanalysis, periodate oxidation and enzymatic digestion, the molecularspecies of the glucans contained in the regenerated cell wallswere deduced to be ß-1,4-glucan (cellulose) and ß-1,3-glucan.Fraction C was mainly composed of ß-1,4-glucan; ß-1,3-glucanwas mainly recovered in fraction K-P. The ß-l,3-glucanwas soluble in dilute alkali solution, but was only slightlysoluble in water. The ß-1,3-glucan had an essentiallyunbranched structure, and its weight average molecular weightestimated by gel permeation chromatography was 4.5–5.0x 104. 1 Present address: Division of Environmental Biology, NationalInstitute for Environmental Studies, Yatabe, Tsukuba, Ibaraki305, Japan (Received May 21, 1981; Accepted October 13, 1981)  相似文献   
42.
Summary Disomic and trisomic cells of a patient with Down syndrome mosaic were used to study the effect of the additional chromosome 21 against an identical genetic background. The frequency of Ag staining and the participation in satellite associations were determined for each pair of acrocentric chromosomes. The additional chromosome 21 of the trisomic cells and its homologues proved to be regularly Ag positive. Therefore the trisomic cells showed more Ag positive chromosomes and more satellite associations per cell than the diploid cells. Thus, no compensation for the additional rRNA-gene dose could be found in the cells of the trisomic line.  相似文献   
43.
Autoantibody-producing B cell lines were established from peripheral blood lymphocytes of patients with systemic lupus erythematosus. Peripheral blood lymphocytes obtained from five of seven patients were successfully transformed by Epstein-Barr virus. Two of four established B lymphoblastoid cell lines examined in this study produced anti-nuclear factor antibodies and one of them produced anti-single-stranded DNA and anti-double-stranded DNA antibodies. These results indicate that B cell clones committed to self antigens are transformed by Epstein-Barr virus and continue to produce autoantibodies. In order to establish a monoclonal autoantibody-producing B cell line, the cells were cloned by a limiting dilution method. The data suggest that it is possible to establish a monoclonal autoantibody-producing B cell line by the combination of transformation of B cells by Epstein-Barr virus and extensive cloning.  相似文献   
44.
The molecular architecture of hemoglobins and their subunits of the earthworms Pheretima communissima and Pheretima hilgendorfi was investigated. In both species, their s0.20,w of 60.8 S and D020,w of 1.80 . 10(-7) cm2 . s-1 corresponded to a molecular weight of 3.07 . 10(6). From electron microscopic observations, the overall structure of the hemoglobins was shown to be two superimposed hexagonal discs, each composed of six-membered constituents. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of both hemoglobins revealed the presence of five species of subunits with molecular weights of 13,000-14,000 (subunit 1), 27,000-28,000 (subunit 2), 30,000-31,000 (subunit 3), 33,000-34,000 (subunit 4) and approx. 52,000 (subunit 5), respectively, and the molar ratio of these subunits 1:2, 3, 4:5 was 2:3:3. If we consider this set of the subunits 1 to 5 as one unit, the molecular weight of this unit should be 2.7-2.8 . 10(5). This one unit, therefore, should be considered to represent one-twelfth the whole molecule with molecular weight of 3.07 . 10(6).  相似文献   
45.
Lemna perpusilla 6746, a short-day duckweed, flowered undercontinuous illumination if some of the SH inhibitors, such ascyanide or tungstate were added to the M-sucrose medium. Theeffect of tungstate was not overcome by simultaneous applicationof molybdate, but deletion of the Mo from the medium was enoughto induce the long-day flowering. In vivo assay of nitrate reductaseactivity suggested that nitrate reduction was not inhibitedby tungstate, CuSO4 or AgNO3 which induced longday flowering.The possibility was suggested that suppression of some Mo-requiringprocess other than nitrate reduction brings about the long-dayflowering in this plant. (Received November 12, 1975; )  相似文献   
46.
The metabolism of d-gluconate-[1-14C] and -[6-14C] by segments from etiolated hypocotyls of Phaseolus mungo has been studied. The release of 14CO2 from gluconate-[1-14C] was greater than that from gluconate-[6-14C] in all parts of hypocotyls examined. Incorporation of the radioactivity from gluconate-[6-14C] into RNA, lignin and aromatic amino acid fractions was greater in the upper (younger) part of the hypocotyls. Incorporation into sugars was greater in the lower (more mature) parts.  相似文献   
47.
Currently, gapmer antisense oligonucleotide (ASO) therapeutics are under clinical development for the treatment of various diseases, including previously intractable human disorders; however, they have the potential to induce hepatotoxicity. Although several groups have reported the reduced hepatotoxicity of gapmer ASOs following chemical modifications of sugar residues or internucleotide linkages, only few studies have described nucleobase modifications to reduce hepatotoxicity. In this study, we introduced single or multiple combinations of 17 nucleobase derivatives, including four novel derivatives, into hepatotoxic locked nucleic acid gapmer ASOs and examined their effects on hepatotoxicity. The results demonstrated successful identification of chemical modifications that strongly reduced the hepatotoxicity of gapmer ASOs. This approach expands the ability to design gapmer ASOs with optimal therapeutic profiles.  相似文献   
48.
The crystal structure of a novel component of the mannan biodegradation system, 4-O-β-d-mannosyl-d-glucose phosphorylase (MGP), was determined to a 1.68-Å resolution. The structure of the enzyme revealed a unique homohexameric structure, which was formed by using two helices attached to the N-terminus and C-terminus as a tab for sticking between subunits. The structures of MGP complexes with genuine substrates, 4-O-β-d-mannosyl-d-glucose and phosphate, and the product d-mannose-1-phosphate were also determined. The complex structures revealed that the invariant residue Asp131, which is supposed to be the general acid/base, did not exist close to the glycosidic Glc-O4 atom, which should be protonated in the catalytic reaction. Also, no solvent molecule that might mediate a proton transfer from Asp131 was observed in the substrate complex structure, suggesting that the catalytic mechanism of MGP is different from those of known disaccharide phosphorylases.  相似文献   
49.
Background. Phospholipids concentration in the gastric mucosa decreased in patients with Helicobacter pylori infection. The aim of this study is to examine the effects of eradication of H. pylori on decreasing the phospholipids concentration in the gastric mucosa in patients with gastric or duodenal ulcer. Materials and Methods. Phospholipids (phosphatidylcholine, phosphatidylethanolamine, and sphingonomyeline) were measured in biopsy specimens from the antrum and corpus using thin‐layer chromatography. In H. pylori positive patients with gastric ulcer (n = 26) and duodenal ulcer (n = 13), and H. pylori negative controls (n = 20), the biopsy specimens were obtained before and 3 months after eradication. Eradication was performed using lansoprazole, amoxycillin, and clarithromycin. Results. Compared with the H. pylori negative control group, the concentrations of phosphatidylcholine and phosphatidylethanolamine decreased significantly in the gastric ulcer group in both antrum and corpus mucosa, and in the duodenal ulcer group in antrum mucosa. This decrease returned to the control level after eradication. Conclusions. This study demonstrates that the eradication of H. pylori in patients with peptic ulcer normalized the decrease of phosphatidylcholine and phosphatidylethanolamine in the gastric mucosa.  相似文献   
50.
The normal excitation and conduction in the heart are maintained by the coordination between the dynamics of ionic conductance of each cell and the electrical coupling between cells. To examine functional roles of these two factors, we proposed a spatially-discrete model of conduction of excitation in which the individual cells were assumed isopotential. This approximation was reasoned by comparing the apparent space constant with the measured junctional resistance between myocardial cells. We used the four reconstruction models previously reported for five kinds of myocardial cells. Coupling coefficients between adjacent cells were determined quantitatively from the apparent space constants. We first investigated to what extent the pacemaker activity of the sinoatrial node depends on the number and the coupling coefficient of its cells, by using a one-dimensional model system composed of the sinoatrial node cells and the atrial cells. Extensive computer simulation revealed the following two conditions for the pacemaker activity of the sinoatrial node. The number of the sinoatrial node cells and their coupling coefficients must be large enough to provide the atrium with the sufficient electric current flow. The number of the sinoatrial node cells must be large so that the period of the compound system is close to the intrinsic period of the sinoatrial node cell. In this simulation the same sinoatrial node cells produced action potentials of different shapes depending on where they were located in the sinoatrial node. Therefore it seems premature to classify the myocardial cells only from their waveforms obtained by electrical recordings in the compound tissue. Second, we investigated the very slow conduction in the atrioventricular node compared to, for example, the ventricle. This was assumed to be due to the inherent property of the membrane dynamics of the atrioventricular node cell, or to the small value of the coupling coefficient (weak intercellular coupling), or to the electrical load imposed on the atrioventricular node by the Purkinje fibers, because the relatively small atrioventricular node must provide the Purkinje fibers with sufficient electric current flow. Relative contributions of these three factors to the slow conduction were evaluated using the model system composed of only the atrioventricular cells or that composed of the atrioventricular and Purkinje cells. We found that the weak coupling has the strongest effect. In the model system composed of the atrioventricular cells, the propagation failure was not observed even for very small values of the coupling coefficient.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
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