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Biomedical subjects

T Horiuchi

Publications and source records attributed to T Horiuchi.

At least 523 records · Page 29Linked to original sources
PubMed1983

Structure and expression of the dnaQ mutator and the RNase H genes of Escherichia coli: overlap of the promoter regions.

A 1.6-kilobase-pair DNA fragment derived from the Escherichia coli chromosome was analyzed by Tn3 transposon insertion and deletion mapping to locate a mutator gene, dnaQ (mutD), and the rnh gene that codes for RNase H. When a strong promoter, PL of lambda phage, was placed at the right- and left-side of the cloned DNA fragment, the dnaQ protein and RNase H, respectively were overproduced. These results suggested that the two genes are transcribed in opposite directions and that their promoters are located in a narrow region between the genes. Nucleotide sequence analysis confirmed this and further revealed that transcriptional and translational initiation signals for the two genes overlap. From the sequence data it was deduced that the dnaQ protein and RNase H consist of 243 and 155 triplets and have molecular weights of 27,500 and 17,500, respectively. dnaQ81 amber mutant showed two codon alterations, CAG(glutamine-195) leads to TAG(amber) and ACA(threonine-193) leads to ATA(isoleucine). The dnaQ-lacZ and the rnh-lacZ fused genes were constructed and hybrid proteins with beta-galactosidase activity were produced. From beta-galactosidase levels it was estimated that the promoter for dnaQ is 5 times more active than that for rnh.

Amino Acid Sequence↗
PubMed1983

New 434-specific DNA binding protein copurified with the 434 tof protein from lambda imm434cI dv carrier cells of Escherichia coli.

A tof-like protein that has 434-specific DNA binding activity has been copurified with the 434 tof protein from lambda imm434cI dv carrier cells. The apparent molecular weight of the new 434-specific DNA binding protein is 9,000 to 9,500, a little higher than that of the 434 tof protein, as estimated by SDS gel electrophoresis. Amino acid analysis revealed the protein to be an arginine-rich component whereas the 434 tof protein is a lysine-rich component. The specific binding reaction of the new protein to lambda imm434dv DNA is distinct from that of the 434 tof protein in respect to the sigmoid shape of the binding curve and to the temperature dependency. This suggests that the specific binding to lambda imm434dv DNA observed with the new protein is due not to a trace of the 434 tof protein contaminating the new protein preparation but rather to the new protein itself. The NH2-terminal 11 residues of the new 434-specific DNA binding protein were sequenced by manual Edman degradation. This technique revealed that the new protein is not a fragment of the 434 tof, cII, or O protein or an NH2-terminal fragment of the cI repressor. The origin and the physiological roles of the new 434-specific DNA binding protein remain unknown.

Amino Acids↗
PubMed1983

Isolation of conditional lethal mutator mutants of Escherichia coli by localized mutagenesis.

By using localized mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine, we isolated 39 temperature-sensitive growth mutants that exhibited high mutability when the bacteria were grown at the permissive temperature. Two of the mutations, dnaQ186 and dnaQ231, were shown to be new alleles of the dnaQ gene by genetic mapping and complementation tests with the dnaQ49 mutation previously isolated. They shared common properties with the dnaQ49 strain, but their mutator activity was not temperature dependent. The dnaQ mutants exhibited increased sensitivity to inhibitors of DNA gyrase and to DNA intercalating and alkylating agents.

Alleles↗
PubMed1983

Isolated aortic origin of right pulmonary artery. Report of a case with special reference to pulmonary vascular disease in the left and right lungs.

Morphometric study of the pulmonary vasculature was performed on lung biopsy specimens from a one-year-old girl who underwent anatomic repair of isolated aortic origin of the right pulmonary artery. Medial hypertrophy of small pulmonary arteries in the right lung was much less remarkable than that in the left lung. In contrast, intimal lesions in the right lung were much more advanced than those in the left lung. Fully oxygenated blood in the right pulmonary artery might suppress medial hypertrophy in response to high pressure and thin media fail to protect intima from high pressure, resulting in severe intimal lesions. This situation in the right lung resembles that in complete transposition of the great arteries.

Aorta↗
PubMed1983

[Caerulein-induced contraction of the ileal longitudinal smooth muscle isolated from various animal species].

An effect of caerulein was studied on a contractile response of the ileal longitudinal smooth muscle isolated from seven animal species, monkey, dog, rabbit, guinea-pig, rat, vole and mouse. In isotonic recording, caerulein induced a contraction in the muscle isolated from all animal species. Sensitivities of ileal strips to caerulein in the contractile response was divided into three groups. That is, a high sensitive group; dog and guinea-pig, a middle sensitive group; rabbit and vole, a low sensitive group; monkey, rat and mouse. In another series of experiment, effect of several antagonists was examined on the caerulein-induced contraction in ileal muscle of dog, rabbit or guinea-pig. TTX inhibited the contractions in all the ilea. As the contraction was inhibited by atropine and scopolamine in dog ileum but not in rabbit one, the contraction may be due to an excitation of the cholinergic neuron or an excitation of non-cholinergic excitatory neuron, respectively. On the other hand, it is supposed that the contraction in guinea-pig ileum is involved to both the neurons because the contraction was inhibited partially by scopolamine and not by atropine. In conclusion, the ilea isolated from seven animal species showed species differences in sensitivity to caerulein in contractile response, and caerulein seems induces the contractions involving to different nervous systems in dog, rabbit or guinea-pig ileum, respectively.

Animals↗
PubMed1983

Cryogel studies for the optimization of cryofiltration (CF) therapy.

This study has shown that cryofilter plugging correlates with pretreatment pathologic macromolecule concentrations (e.g. rheumatoid factor and immune complexes) in the treatment of patients with rheumatoid arthritis. Pathologic macromolecules are concentrated relative to albumin in the cryogel. Molecular aggregation in the cryogel depends upon heparin concentration, exhibiting maximum aggregation in a specific range of heparin concentrations. Molecular aggregation in cryogel increases with decreasing temperature. In the use of cryofiltration in over 50 rheumatoid arthritis patients, clinical improvement has accompanied the removal of cryogel and the pathologic macromolecules it contains. Filter plugging or cryogel formation may be indicators of disease activity. Formation of cryogel is variable depending upon type of disease, severity of disease, temperature, heparin concentration, and membrane structure. These factors are important parameters to consider to optimize conditions for removal of cryogel and for continuing improvement of plasma therapeutic techniques for the treatment of rheumatoid arthritis.

Arthritis, Rheumatoid↗
PubMed1983

Chronological observations on hemato-pathological changes in chicks inoculated with chicken anemia agent.

Chicks were inoculated with the Gifu-1 strain of the chicken anemia agent (CAA) on the day of hatching. They manifested distinct anemia accompanied with pancytopenia 8--20 days after inoculation. Discoloration of the bone marrow and atrophy of the thymus began to be seen 6 days after inoculation. Histologically, hematopoietic cells began to decrease and large blastic cells to appear in the bone marrow 4--6 days after inoculation. Hypoplasia and subsequently aplasia occurred to all over the bone marrow 8 days after inoculation. In the bone marrow erythrocytopoiesis was noticed first 16--18 days after inoculation, granulocytopoiesis later, and transient hyperplasia finally. At last, the bone marrow returned to a normal condition 32 days after inoculation or later. In the thymus the depletion of cortical lymphocytes became distinct 4--6 days after inoculation, and lobular atrophy 8 days after inoculation or later. The depletion of lymphocytes in the other lymphatic tissues and hemorrhage in the lamina propria of the proventriculus were observed only in the anemic phase. The results mentioned above indicated that the anemia induced by CAA was caused by the disorder of hematopoietic cell formation in the bone marrow. It was also noteworthy that cortical lymphocytes in the thymus began to decrease remarkably soon after inoculation.

Anemia↗
PubMed1983

[Sequential observation of human sperm penetration into zona pellucida-free hamster oocytes by scanning electron microscopy].

Yanagimachi et al. have shown that zona pellucida-free hamster oocytes can be penetrated by capacitated and acrosome-reacted human spermatozoa, and both pronuclei be formed. Recently, it has been said that this technique may be used to test the fertilizing ability of human sperm for clinical use. We have made scanning electron microscopic studies of the interaction of these heterologous gametes, especially the mechanisms of sperm entry into the oocytes. Our results are as follows: The surface of the oocyte is covered with numerous microvilli, which are found to be evenly and densely distributed on the vitellus surface. The surface of the first polar body already released is smooth and microvilli-free. Most spermatozoa lie flat on the vitellus surface, but a few are oriented perpendicularly to the vitellus surface. Most bound sperm had lost their acrosomal caps, because a ridge exists at the leading edge of the equatorial segment. Many microvilli are shown to participate in sperm-egg contact. Initially most microvilli appeared to grasp and immobilize the anterior tip of the sperm head. But as gamete interaction proceeded, microvilli were overlying the postacrosomal region, and observed adjacent to the plasma membrane of the postacrosomal region. The postacrosomal region is first incorporated into the ooplasma, the anterior tip of sperm head being the last portion to be incorporated. The microvilli of the oolenmal surface where sperm penetrated did not show major changes in size or appearance, and the so-called "incorporation cone" was not observed. Our scanning electron micrographs show that the microvillar portion of the oolenma greatly participates in this heterologous gamate interaction.

Animals↗
PubMed1982

Coliphage 434 tof Protein: NH2-terminal amino acid sequence and kinetic and equilibrium measurements of DNA binding.

Coliphage 434 tof protein was purified to a substantially pure state from lambda imm434 cI dv carrier cells. The minimum molecular weight is 7,500 +/- 500 as estimated by polyacrylamide gel electrophoresis. The amino acid sequence of the nine NH2-terminal residues was determined, by manual Edman degradation of the intact protein, to be Met-Gln-Thr-Leu-Ser-Glu-Arg-Leu-(Lys)-. The purified protein at low concentrations binds specifically to lambda imm434 dv DNA and at high concentrations also binds to lambda imm21 dv and lambda dv DNA. The curve of the specific binding is of Michaelis type, while that of the nonspecific binding is sigmoidal. The specific binding does not show marked temperature dependency at 4 degrees - 37 degrees C. We have analyzed the equilibrium and kinetic data of specific binding. The equilibrium dissociation constant is 1.9 X 10(-11) M at O degree C. The association rate constant and the dissociation rate constant are 1.1-2.9 X 10(8) M-1s-1 and 2.7 X 10(-3)s-1, respectively, at 0 degrees C. The half life of the tof protein-operator DNA complex is 260 s. These results suggest that the tof protein-operator interaction is much weaker than the interaction between the cI repressor and the operator reported by other workers.

Amino Acid Sequence↗
PubMed1982

Structure of the lambda tof repressor protein in solution. Heat stability and its relation to binding ability to DNA.

The lambda tof repressor protein was purified from E. coli cells retaining lambda dv plasmids by applying DNA-cellulose chromatography. 3H-labeled lambda dv and lambda imm21dv DNA, carrying and lacking lambda operators, respectively, were prepared and the binding activity of the lambda tof protein to the DNA was examined. Non-specific binding to lambda imm21dv DNA is completely lost at 30 degrees C, whereas specific binding to the DNA carrying the operators is retained even above 40 degrees C. The conformation of the lambda tof protein was analysed by means of circular dichroism and 1H-NMR spectra. The change in the molar ellipticity at 222 nm vs. temperature in CD spectra indicated a transition between two states with Tm at 42 degrees C. The 360 MHz 1H-NMR spectra revealed the presence at 20 degrees C of another change in local conformation of interaction which was not detected by the CD spectra. 1H-NMR also indicated the coexistence of thermal transitions with exchange rates faster and slower than the NMR time scale at about 50 degrees C, which is explained by the presence of domain structures. The NMR titration curve of the His residue gave a normal pK value showing its location on the surface of the protein. These conformational behaviors are well correlated to the specific and non-specific DNA binding activity of the lambda tof protein. The assignments of 1H resonance signals to some specific residues, including His 35 and Tyr 26, were established. It will be useful to determine the tof-DNA interaction.

Bacterial Proteins↗