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Y Hotta

Publications and source records attributed to Y Hotta.

At least 19 recordsLinked to original sources
PubMed1992

The synthesis of cadystins, heavy metal chelating peptides, is induced in the fission yeast by wounds of the cell wall or by incubation with chitosan.

It has been shown that heavy metal administration induced the synthesis of cadystins, the small metal chelating peptide with the general structure of (gamma-glu-cys)n-gly, in the fission yeast and in plants. Besides heavy metals, wounds to the cell surface or the incubation with chitosan induced the cadystin synthesis in the fission yeast. Under these induction conditions, the membrane permeability of the fission yeast significantly increased suggesting the structural alteration of the membrane. In these induction, the synthesized cadystins formed complexes with the cellular zinc ions together with or without glutathione.

Amino Acid Sequence↗
PubMed1992

Monoclonal antibodies which stain small subsets of neurons in the Drosophila central nervous system.

Monoclonal antibodies (MAbs) specific to small subsets of neurons in the central nervous system (CNS) of Drosophila melanogaster were described. MAbs 43A8, 45C6 and 65C11, which were obtained in fusion experiments using the third instar larval or prepupal CNS as an immunogen, stained a small number of neurons in the postembryonic CNS. Functional implications of the observed immunoreactivities during neural development in the Drosophila CNS are discussed.

Animals↗
PubMed1992

Partial purification and characterization of membrane-associated diacylglycerol kinase of Drosophila heads.

A membrane-associated diacylglycerol kinase of Drosophila heads was purified to near homogeneity from the KCl extract of Drosophila heads. The purification procedure involved chromatography on Q-Sepharose, ammonium sulfate fractionation, Superose 12, hydroxyapatite and ATP-agarose. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of fractions after the ATP-agarose column chromatography showed that only a 115 kDa protein correlated well with the enzyme activity. The apparent Km values of partially purified DG kinase were 220 microM for ATP and 540 microM for diolein, respectively. The activity of the DG kinase was inhibited by deoxycholate and was not activated by Ca2+.

Animals↗
PubMed1992

Molecular cloning of a Drosophila diacylglycerol kinase gene that is expressed in the nervous system and muscle.

We have isolated a Drosophila melanogaster diacylglycerol kinase (DGK, EC 2.7.1.107) homologue by using a porcine DGK cDNA probe and we have characterized its structure and expression. The DGK cDNA has a single open reading frame that encodes 791 amino acids. The Drosophila and porcine DGKs share a similar carboxyl-terminal region, a putative catalytic domain, which is divided into two separate domains in Drosophila. The DGK gene was mapped to the cytogenetic position 43F1, and its DGK mRNA is abundant both in embryo and in adult fly. By in situ hybridization to sections of adult flies, we demonstrated that the mRNA is present predominantly in the nervous system and muscles, including compound eyes, brain cortex, fibrillar muscle, and tubular muscle. In a 10- to 11-hr embryo, the DGK gene is expressed abundantly in a limited number of cells in the procephalic region and in the ventral nerve cord. The pattern of temporal and spatial expression suggests that the DGK protein has an important function in the adult nervous system and muscle and during the development of the embryonic nervous system.

Amino Acid Sequence↗
PubMed1992

A deletion in the ornithine aminotransferase gene in gyrate atrophy.

Gyrate atrophy (GA) is an autosomal recessive chorioretinal degenerative disease of the eye caused by an inborn defect of the nuclear encoded mitochondrial enzyme ornithine aminotransferase (OAT). We have described previously a GA patient with a 5.0-kilobase pair truncated EcoRI OAT gene fragment and the absence of OAT mRNA on Northern blot analysis. Cloning and sequencing analysis of the truncated gene fragment revealed a 1,072-base pair (bp) deletion including the entire exon 6, starting in intron 5, 172 bp upstream of exon 6 and ending in intron 6, 772 bp downstream of exon 6. A short direct repeat sequence (AGGAGC), resembling the sequence shown to cause DNA polymerase alpha to pause, and sequences capable of forming hairpin loops were both present at the 5' and 3' break-points of the deletion. Reverse transcription-polymerase chain reaction amplification of the patient's RNA with OAT primers yielded DNA fragments of two different sizes, consistent with a low level expression of OAT mRNA. Direct sequencing of the smaller fragment demonstrated the complete absence of exon 6 sequence in the mRNA predicted from the deletion, causing a reading frame shift which results in a premature termination codon at position 192. The mutation in the other allele has been demonstrated by polymerase chain reaction, denaturing gradient gel electrophoresis, and direct sequencing also to be a premature termination codon in exon 6. The absence of detectable OAT mRNA in this patient is consistent with these premature termination mutations because they have been shown to decrease the level of mRNA, especially if present early in the coding sequence.

Amino Acid Sequence↗
PubMed1992

An antigen present in the Drosophila central nervous system only during embryonic and metamorphic stages.

We report here about an antigen that is expressed in the central nervous system (CNS) of Drosophila only during the embryonic and metamorphic stages. In Drosophila, axonogenesis and synaptogenesis occur twice during the development: first in the embryonic and second in the metamorphic stages. We generated monoclonal antibodies (MAbs) in order to obtain molecular probes for analyzing axonogenesis or synaptogenesis in the CNS on the assumption that good candidates for molecules responsible for such phenomena must be present in the neuropil during those stages exclusively. As a result, we found MAb 66B2 whose intense immunoreactivity in the neuropil of the CNS was observed exclusively in the embryo and pupa, and not in the larva and adult. Immunoblot analyses showed that MAb 66B2 binds specifically to a protein with an apparent molecular weight of 350 K and neutral pI in the prepupal CNS. A significant amount of the antigen was isolated in forms that were soluble without detergent. Results of immunohistochemistry with MAb 66B2 in a primary culture of embryos showed that some live cells in the ganglion-like cluster were stained, and that neuronal cell bodies and neurites emanating from there were negative. These results strongly suggest that the 66B2 antigen observed in the CNS is an extracellular matrix component secreted from nonneuronal cells. These developmental changes in the 66B2 immunoreactivity in the CNS presumably reflect dynamic changes of an extracellular matrix in the CNS that are accompanied by axonogenesis or synaptogenesis.

Animals↗
PubMed1992

Extra sequences found at P element excision sites in Drosophila melanogaster.

We have previously established a transgenic Drosophila line with a highly transposable P element insertion. Using this strain we analyzed transposition and excision of the P element at the molecular level. We examined sequences flanking the new insertion sites and those of the remnants after excision. Our results on mobilization of the P element demonstrate that target-site duplication at the original insertion site does not play a role in forward excision and transposition. After P element excision an 8 bp target-site duplication and part of the 31 bp terminal inverted repeat (5-18 bp) remained in all the strains examined. Moreover, in 11 out of 28 strains, extra sequences were found between the two remaining inverted repeats. The double-strand gap repair model does not explain the origin of these extra sequences. The mechanism creating them may be similar to the hairpin model proposed for the transposon Tam in Antirrhinum majus.

Animals↗
PubMed1992

Point mutations of rhodopsin gene found in Japanese families with autosomal dominant retinitis pigmentosa (ADRP).

The mutations of codon 17, 23, 58, and 347 of rhodopsin gene were investigated in 24 unrelated Japanese families including 33 patients with autosomal dominant retinitis pigmentosa (ADRP). A patient with codon 17 mutation (Thr-17-Met, ACG-->ATG) and a family including 4 patients with codon 347 mutation (Pro-347-Leu, CCG-->CTG) were detected among them. Their clinical findings were extremely different between the two mutations. The former showed type 2 and the latter showed type 1 ADRP. No mutation of codon 23 and 58 was detected in any families so far analyzed in the present study. Clinical findings associated with the mutation in codon 17 and 347 of the rhodopsin gene show an existence of allelic heterogeneity.

Adolescent↗
PubMed1992

Proliferation pattern of postembryonic neuroblasts in the brain of Drosophila melanogaster.

The spatio-temporal proliferation pattern of postembryonic neuroblasts in the central brain region of the supra-esophageal ganglion of Drosophila melanogaster was studied by labeling DNA replicating cells with 5-bromo-2'-deoxyuridine (BrdU). There are five proliferating neuroblasts per hemisphere in larvae just after hatching: one in the ventro-lateral, and the other four in the postero-dorsal region of the brain. Dividing neuroblasts increase during the late first-late second instar larval stages, reaching a plateau of about 85 neuroblasts per hemisphere. Most neuroblasts cease dividing 20-30 hr after puparium formation (APF), while only four in the postero-dorsal region continue making progenies until 85-90 hr APF. The four distinct neuroblasts proliferating in the early larval and late pupal stages are identical; they lie in the cortex above the calyces of the mushroom bodies (corpora pedunculata), proliferating over a period twice as long as that for the other neuroblasts. Their daughter neurons project into the mushroom body neuropile, and hence are likely to be the Kenyon cells. The cell-cycle period of the four neuroblasts (named mushroom body neuroblasts: MBNbs) is rather constant (1.1-1.5 hr) during the mid larval-early pupal stages and is longer before and after that. The total number of the MBNb progenies made throughout the embryonic and postembryonic development was estimated to be 800-1200 per hemisphere.

Animals↗
PubMed1992

Isolation of cDNA for bovine stomach 155 kDa protein exhibiting myosin light chain kinase activity.

Two proteins with myosin light chain kinase activity and electrophoretic molecular weights of 155,000 and 130,000 were each isolated from bovine stomach smooth muscle [Kuwayama, H., Suzuki, M., Koga, R., & Ebashi, S. (1988) J. Biochem. 104, 862-866]. The 155 kDa component showed a much higher superprecipitation-inducing activity than the 130 kDa component, when compared on the basis of equivalent myosin light chain kinase activity. In this study, we isolated a cDNA for the entire coding region of the 155 kDa protein. The deduced amino acid sequence revealed a high degree of similarity to those of chicken and rabbit smooth muscle myosin light chain kinases. Multiple motifs, such as three repeats of an immunoglobulin C2-like domain, a fibronectin type III domain, and unusual 20 repeats of 12 amino acids were detected in the sequence. Part of the amino-terminal sequence was similar to that of the actin- and calmodulin-binding domain of smooth muscle caldesmon. These observations suggest that the 155 kDa protein has additional functions other than its enzymatic activity. Two mRNAs of 6.0 and 2.6 kb in length in the bovine stomach smooth muscle RNAs were hybridized with cDNA probes. The 2.6-kb RNA probably encodes telokin, which is the carboxyl terminus of smooth muscle myosin light chain kinase. mRNAs with identical lengths were also detected in bovine aorta.

Amino Acid Sequence↗
PubMed1992

Changes in intracellular cAMP level and activities of adenylcyclase and phosphodiesterase during meiosis of lily microsporocytes.

In the yeasts, Saccharomyces cerevisiae and Schyzosaccharomyces pombe, reduction of intracellular cyclic adenosine monophosphate (cAMP) is known to trigger the sporulation processes by activating various meiosis specific genes. In order to ascertain whether a similar mechanism is operative in higher plants, we carried out preliminary studies on lily microsporocytes. Measurement of cAMP levels as well as the activities of adenyl cyclase and phosphodiesterase in somatic cells and different stages of meiosis, and arrest of its in protoplasts cultured under conditions of high cAMP provided direct evidence that similar phenomena occur in plant meiocytes as earlier documented in yeasts.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1992

Studies on cardiac ingredients of plants. IX. Chemical transformation of proscillaridin by utilizing its 1,4-cycloadducts as key compounds and biological activities of their derivatives.

Three aromatic compounds (2-4) possessing a carbomethoxyl group or a dimethoxyphthaloyl group, prepared by the Diels-Alder reaction of the cardiac glycoside, proscillaridin (1), with dimethyl acetylenedicarboxylate and methyl propiolate, were transformed into alcohols, carboxylic acids and amides. The biological activities of the resulting derivatives were evaluated by the use of Na+, K(+)-adenosine triphosphatase (Na+,K(+)-ATPase) from dog kidney and isolated guinea-pig papillary muscle. Although the biological activities of the resulting derivatives were less potent than that of 1, a para-substituted benzylalcohol (5), methylbenzamides (9a and 10a), and ethylbenzamides (9b and 10b) inhibited the activity of Na+,K(+)-ATPase almost as potently as naturally occurring cardiac glycosides such as digoxin and digitoxin.

Animals↗
PubMed1992

[Studies on cardiac ingredients of plants. X. Preparation of nitrates of tetrahydroproscillaridin and their pharmacological activities].

To reduce the vascular contracting effect of the hydrogenated cardiac glycosides, 20-(R)- and 20-(S)-tetrahydroproscillaridins (THPs, 1a, 1b), and to extend the concentration-dependent range, mono- and dinitrates of THPs were prepared. The pharmacological activities of the nitrates of THP were evaluated by use of isolated guinea-pig papillary muscle preparations and Na+,K(+)-adenosine triphosphatase preparations from dog kidney. Furthermore, the effect for smooth muscle was examined using the helical strips isolated from 13-week-old spontaneously hypertensive rat. The positive inotropic effects of mononitrates (11a, 11b, 2a, 2b, 8a, and 8b) were more potent than those of THPs. Nitration of the sugar moiety in THPs resulted in a vascular relaxing effect unobserved in the case of THPs.

Animals↗
PubMed1992

[23Na-NMR measurements of the sodium concentration in guinea pig erythrocytes: the effects of cardiac glycoside and asebotoxin III].

Intra- and extracellular sodium in guinea pig erythrocytes was evaluated with sodium-23 nuclear magnetic resonance (23Na-NMR) by the use of a shift reagent, Dy(TTHA)3- or Dy(PPPi)2(7-). The test medium contained erythrocytes at 40% hematocrit level and NMR buffer (145 mM NaCl, 10 mM Dy(TTHA)3-, 10% D2O, adjusted to pH 7.4 with tris, at 35 degrees C). NMR spectra were obtained with a JEOL GSX 400 spectrometer operating at the Fourier transform mode of resonance signals, and the accumulated signals provoked by radio-frequency pulses of 90 degrees were recorded on paper. Quantitative Na determination was performed by measuring the area under the peak of intracellular sodium (Nai) NMR signals. Ouabain (Oua: 0.3 mM) and asebotoxin-III (ATX-III: 0.3 mM) produced an increase in Nai-NMR signals to a level of 188.1% and 138.1% of the control, respectively. Combined use of Oua (0.15 mM) and ATX-III (0.15 mM) produced an elevation of Nai concentration to a high level of 219.0% of the control in a superadditive manner. Mechanisms of the Nai elevation with Oua and ATX-III can be interpreted by assuming two different actions: ATX-III increases net Na(+)-influx via Na+ channels, while Oua inhibits the pumping out of Na+ from the cell.

Animals↗
PubMed1992

[Molecular biological study of the rhodopsin gene in Japanese patients with autosomal dominant retinitis pigmentosa].

The author analyzed codon 347 of the rhodopsin gene using PCR (polymerase chain reaction) amplification and restriction enzymes in 19 unrelated Japanese families including 28 patients with autosomal dominant retinitis pigmentosa (ADRP). An allele of codon 347 mutation was found in a family (father and daughter). Sequence analysis shows that the mutation is from CCG to CTG. This mutation appears to be the cause of one form of ADRP, since it was also found in Japanese cases of ADRP which have a different racial background from families reported by Dryja et al.

Codon↗
PubMed1992

Expression of human ornithine aminotransferase (OAT) in OAT-deficient Chinese hamster ovary cells and fibroblasts of gyrate atrophy patient.

Gyrate atrophy is a hereditary chorioretinal degenerative disease caused by a deficiency of the mitochondrial enzyme, ornithine aminotransferase (OAT). Recent investigations have demonstrated the molecular genetic defects of OAT in gyrate atrophy patients. We constructed a eukaryotic expression vector (pcDHOAT) which contains the SV40 promoter and human OAT cDNA. We used OAT(-) Chinese hamster ovary (CHO) cells, which have negligible OAT activity, and fibroblasts from a gyrate atrophy patient (GA35 cell), which have negligible OAT mRNA and enzyme. Incorporation of pcDHOAT and synthesis of human OAT mRNAs and active enzyme were demonstrated in both cell types. The level of expression of human OAT was low in the GA35 cells in comparison to the CHO cells. Despite the limited success, the ability to express active OAT in these OAT-deficient cells using an expression vector offers possibilities of replacement gene therapy for gyrate atrophy.

Animals↗
PubMed1992

High frequency of mitochondrial ND4 gene mutation in Japanese pedigrees with Leber hereditary optic neuropathy.

The association of the ND4 gene mutation (mutation) at nucleotide position 11778 of mitochondrial DNA (mtDNA) was investigated in 14 definitive Japanese pedigrees with Leber hereditary optic neuropathy (LHON). The mutation was detected by SfaNI and MaeIII restriction fragment length polymorphisms of mtDNA amplified by polymerase chain reaction. All 14 LHON pedigrees exhibited the mutation, whereas 10 controls did not. The association of this mutation with LHON was revealed to be significantly higher in Japanese (91.7%) than in 27 reported Caucasian (51.9%) LHON pedigrees, implying genetic heterogeneity. In the tested 14 pedigrees, 28 cases with the mutation comprised 19 affected (17 male and 2 female) and 9 asymptomatic (all female except for one) individuals. Such a predominance of males in the incidence of LHON suggested probable participation of additional pathogenetic factor(s) in the development of optic atrophy in LHON patients.

Adolescent↗