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T Mukai

Publications and source records attributed to T Mukai.

At least 253 records · Page 14Linked to original sources
PubMed1990

The rare inversion with a P element at the breakpoint maintained in a natural population of Drosophila melanogaster.

We found a rare inversion which is superimposed on the In(2R) NS chromosome. It has been maintained for several years in the Raleigh, N.C., USA population and possibly for more than ten years in the southern populations of the USA. Both the breakpoint of the rare inversion and the corresponding site of the In(2R) NS chromosome have P elements and therefore, the rare inversion might be induced by P element activity in a natural population.

Animals↗
PubMed1990

Transcriptional regulation of an aldolase gene in the regenerating rat liver.

The relative abundance of rat aldolase A, B, C, alpha-fetoprotein, and albumin mRNAs was determined by Northern hybridization during liver regeneration after partial hepatectomy. Aldolase A mRNA increased more than 10-fold on the 3rd day after partial resection compared with that of normal adult rat liver. S1 analysis revealed that three species of aldolase A mRNAs (mRNA I, II & III) reappeared. However, transcriptional rate of aldolase A mRNA did not change at all during the regeneration. In contrast, aldolase B, aldolase C and albumin mRNAs did not change at all. These findings suggest that the differentiated hepatocyte maintains a differentiated state during the liver regeneration as seen in aldolase B, whereas "oncofetal" isozymes such as aldolase A resurge after partial hepatectomy under the control of post-transcriptional mechanism.

Albumins↗
PubMed1990

Transposition rates of movable genetic elements in Drosophila melanogaster.

A considerable proportion of visible mutations is reported to be caused by the insertion of mobile genetic elements in Drosophila and other organisms. We estimated transposition rates of some Drosophila mobile elements by using the lines AW and JH in which spontaneous mutations have been accumulated independently for about 400 generations. Occupied sites of the mobile elements were detected by in situ hybridization on the salivary gland chromosomes sampled from 40 AW and 30 JH lines. The rates of insertion and excision of the copia and two copia-like elements, 412 and 17.6, are very low: Insertions occurred at up to 10(-3) per second chromosome per generation (17.6) and excision occurred at about 10(-5) per site per generation (copia and 412). Insertions of the I and hobo elements occurred much more frequently. These estimates are not only important for assessing the actual rate of various types of mutations but also for developing an evolutionary theory of mobile elements themselves.

Animals↗
PubMed1990

Increased variation in ADH enzyme activity in Drosophila mutation-accumulation experiment is not due to transposable elements at the Adh structural gene.

We present here a molecular analysis of the region surrounding the structural gene encoding alcohol dehydrogenase (Adh) in 47 lines of Drosophila melanogaster that have each accumulated mutations for 300 generations. While these lines show a significant increase in variation of alcohol dehydrogenase enzyme activity compared to control lines, we found no restriction map variation in a 13-kb region including the complete Adh structural gene and roughly 5 kb of both 5' and 3' sequences. Thus, the rapid accumulation of ADH activity variation after 28,200 allele generations does not appear to have been due to the mobilization of transposable elements into or out of the Adh structural gene region.

Alcohol Dehydrogenase↗
PubMed1990

Human aldolase A of a hemolytic anemia patient with Asp-128----Gly substitution: characteristics of an enzyme generated in E. coli transfected with the expression plasmid pHAAD128G.

Aldolase A derived from a hemolytic anemia patient with aldolase A deficiency was shown to have an amino acid substitution of glycine for aspartic acid at the 128th position (Asp-128) in the enzyme [Kishi et al. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 8623-8627]. We constructed an Escherichia coli expression plasmid, pHAAD128G, which carries the mutant aldolase A [aldolase A(D-G)] cDNA, and the enzyme generated in E. coli transfected with the expression plasmid was purified and characterized. Conversion of Asp to Gly at the 128th position in the enzyme rendered the enzyme thermolabile and susceptible to tryptic digestion. CD spectra analysis also revealed that the mutant enzyme had a remarkable conformation change with a decrease of regular form in the molecule. Addition of glycerol or some other polyalcohols during thermal treatment protected this altered enzyme (but not the normal enzyme) against denaturation and activity decrease. In order to determine the function of the amino acid residue at the 128th position, two artificial mutant enzymes with the substitutions of Glu for Asp [aldolase A(D-E)] and Ser for Asp [aldolase A(D-S)], respectively, at the position were constructed by site-directed mutagenesis and characterized. These analyses demonstrated the necessity for Asp to be present at the 128th residue in order for this enzyme to be thermally stable.

Amino Acid Sequence↗
PubMed1990

Preparations of 5-alkylmethylidene-3-carboxymethylrhodanine derivatives and their aldose reductase inhibitory activity.

Reactions of 3-carboxymethylrhodanine (1) with aldehydes (2a-u) afforded stereoselectively the 5-mono-alkylmethylidene-3-carboxymethylrhodanines (3a-u). The configuration of the 5-monoalkylmethylidene-3-carboxymethylrhodanine (3k) were examined by X-ray structure analysis and confirmed to be Z-configuration. The stereoselective reaction path was discussed. Several 5-dialkylmethylidene-3-carboxymethylrhodanines (15a-f) and alkylamino derivatives of 3-carboxymethylrhodanines (18a-o) were also prepared. These products were evaluated for aldose reductase-inhibitory potency and half of them exhibited valuable inhibitory potency.

Aldehyde Reductase↗
PubMed1990

Some consideration on diversifying selection.

The diversifying selection due to genotype-environment interaction can increase the genetic variation in natural populations. It is known, however, that the conditions for stable genetic polymorphism or marginal overdominance are quite restricted in this selection model. In this paper a simple model of diversifying selection was examined, and the following results were obtained: (1) Even when the conditions for marginal overdominance are not satisfied, if the diversifying selection is operating, the frequency of mutants can be higher than that in the case of simple mutation-selection balance. (2) This selection model causes a large amount of genetic load (environment load), even when the conditions for marginal overdominance are not satisfied, namely even when the equilibrium frequency of mutant is very low. From these results it can be concluded that the number of loci on which this type of diversifying selection is operating is very small, if any.

Animals↗
PubMed1990

Glucose consumption and rate constants for 18F-fluorodeoxyglucose in human gliomas.

To investigate the value of direct measurement of the rate constants by performing 18F-labeled fluorodeoxyglucose (FDG) studies of glucose consumption in human gliomas in vivo, a kinetic method with 3- and 4-parameter rate constant models for FDG uptake was used to analyze data from dynamic scans obtained by positron emission tomography after injection of FDG into 14 patients with glioma. The results were compared with those obtained by the autoradiographic method using 3- and 4-parameter rate constant models. There were no significant differences in the glucose consumption calculated by the four different methods both in the gliomas and in the contralateral intact cortex. It was found that the rate constant k4* could be neglected in calculation of glucose consumption in gliomas as well as in the contralateral intact cortex. The rate constant k3*, an index of hexokinase function, was higher in malignant gliomas than in benign gliomas and was close to that in the contralateral cortex. This study indicates that the 3-parameter autoradiographic method, which is the most common one used in clinical practice, is reliable for the calculation of glucose consumption in human gliomas. Furthermore, direct measurement of the regional rate constants for FDG by the kinetic method was found to be useful for evaluation of the biochemical and physiological characteristics of human gliomas in vivo.

Adult↗
PubMed1990

Histamine lipolysis I: changes in the free fatty acid levels of dog plasma after intravenous infusion of histamine.

The effects of histamine (Hi) and related compounds on free fatty acid (FFA) levels and % changes in FFA composition of dog plasma were studied after intravenous infusion. Hi at doses of 2-10 micrograms/kg while affecting no changes in the cardiovascular system elicited a dose-related increase in FFA levels in plasma, as did epinephrine. Though all of the FFA concentrations in plasma were increased by Hi infusion, % change of each FFA in the composition did not correspond to that of plasma concentration; % increases in palmitoleic acid, linolenic acid and linoleic acid were remarkable, while stearic acid (18:0) was lowest. The increase in arachidonic acid was not marked, but a dose-related increase was observed after Hi infusion. The H2-agonist 4-methylHi produced an increase in FFA levels, whereas the H1-agonist 2-methylHi was not effective. 4-MethylHi increased all of the plasma FFA levels and the relative changes were similar to those caused by Hi. The effect induced by Hi was blocked by the H2-antagonists cimetidine and ranitidine. Pretreatment with aminophylline potentiated the Hi effect, indicating that Hi lipolysis may be intimately related to cyclic AMP.

Aminophylline↗
PubMed1990

Structural studies on aldolase isozymes through protein engineering.

Enzymatic studies on aldolase isozymes have been carried out by techniques of protein engineering. Site-directed mutagenesis helps us to verify the roles of amino acid residues in catalytic reactions. Chimeric fusion proteins give us information about the regions which specify the characteristics of the isozymes. The results are: (1) In aldolase A, COOH terminal Tyr and Lys-107 residues play important roles in catalysis, especially in binding of FDP. (2) Aspartic acid at the 128th residue in aldolase A is essential to thermostability; no other residue such as glutamic acid can substitute for it. (3) Studies on chimeric fusion proteins indicate that the C-terminal region (including C-terminus Tyr) or aldolase A is responsible for its substrate specificity, which is not seen in aldolase B. (4) A region near NH2 terminus in aldolase B determines its specific structure. (5) The region including His-107, Asp-128, and Tyr-137 (B-A junction of BA137) is located in a turn which is exposed outward (a model architecture by Sygusch et al [1987]). In BA137, this region would be constrained, and play a significant role in catalysis, thermostability, etc. (6) Tertiary structure of aldolase B seems to be dissimilar to that of aldolase A.

Amino Acid Sequence↗
PubMed1990

Hereditary fructose intolerance caused by a nonsense mutation of the aldolase B gene.

The nucleotide sequence of a patient's aldolase B gene was determined and showed a substitution of a single nucleotide (C----A) at position 720 in the coding region, which resulted in the 240th amino acid, a cysteine, being changed to a stop codon (TGC----TGA). By an allele-specific oligonucleotide probe and polymerase chain reaction, the patient was shown to be homozygous for the mutation. To examine whether this mutation causes functional defect of the enzyme, the activity of the aldolase B from the patient, expressed in Escherichia coli by using expression plasmid, was measured. No activity was observed, and the predicted product was recovered from E. coli expression plasmid, indicating that this nonsense mutation was the cause of aldolase B deficiency.

Base Sequence↗
PubMed1990

[Principle and instruments of bone densitometry].

Various methods for measurement of bone densitometry have been developed over the past two decades. This paper discribes the basic principle, technical characteristics and clinical performance on the SPA, DPA, QCT and newly developed DEXA. Advantage of SPA is low cost with high precision, but the method is used to measure only the distal radius. QCT can measure only the trabecular bone from the cortex, but requires high radiation dose. DEXA is similar in concept to DPA, but affords many advantages, i.e. higher precision, higher resolution, shorter examination time and lower dose than the DPA. This new DEXA should allow more accurate and precise management in patients with metabolic bone diseases.

Absorptiometry, Photon↗
PubMed1989

Sequence, structure and evolution of the gene coding for sn-glycerol-3-phosphate dehydrogenase in Drosophila melanogaster.

We present the complete nucleotide and deduced amino acid sequence for the gene encoding Drosophila sn-glycerol-3-phosphate dehydrogenase. A transcription unit of 5kb was identified which is composed of eight protein encoding exons. Three classes of transcripts were shown to differ only in the 3'-end and to code for three protein isoforms each with a different C-terminal amino acid sequence. Each transcript is shown to arise through the differential expression of three isotype-specific exons at the 3'-end of the gene by a developmentally regulated process of 3'-end formation and alternate splicing pathways of the pre-mRNA. In contrast, the 5'-end of the gene is simple in structure and each mRNA is transcribed from the same promoter sequence. A comparison of the organization of the Drosophila and murine genes and the primary amino acid sequence between a total of four species indicates that the GPDH gene-enzyme system is highly conserved and is evolving slowly.

Amino Acid Sequence↗
PubMed1989

Construction and expression of human aldolase A and B expression plasmids in Escherichia coli host.

E. coli expression plasmids for human aldolases A and B (EC 4.1.2.13) have been constructed from the pIN-III expression vector and their cDNAs, and expressed in E. coli strain JM83. Enzymatically active forms of human aldolase have been generated in the cells when transfected with either pHAA47, a human aldolase A expression plasmid, or pHAB 141, a human aldolase B expression plasmid. These enzymes are indistinguishable from authentic enzymes with respect to molecular size, amino acid sequences at the NH2- and COOH-terminal regions, the Km for substrate, fructose 1,6-bisphosphate and the activity ratio of fructose 1,6-bisphosphate/fructose 1-phosphate (FDP/F1P), although net electric charge and the Km for FDP of synthetic aldolase B differed from those for a previously reported human liver aldolase B. In addition, both the expressed aldolases A and B complement the temperature-sensitive phenotype of the aldolase mutant of E. coli h8. These data argue that the expressed aldolases are structurally and functionally similar to the authentic human aldolases, and would provide a system for analysis of the structure-function relationship of human aldolases A and B.

Amino Acid Sequence↗
PubMed1989

Transcription of rat aldolase B gene: minor RNAs are transcribed by RNA polymerase III.

Rat aldolase B gene was confirmed to have multiple transcriptional initiation sites; one site for the major transcript and at least two sites for the minor transcripts which are located at about 30 to 60 bases upstream of the major site. Although the transcription of the minor transcripts was entirely resistant to 1 microgram/ml of alpha-amanitin, which inhibits RNA polymerase II, it was completely blocked by 1000 micrograms/ml of the drug which inhibits RNA polymerase III. The box A- and B-like sequences, which are known to exist in the internal split promoter region of class III genes, were also found to be located around the initiation sites of two minor transcripts from the rat aldolase B gene. Analyses using deletion mutants of the promoter region of the gene suggested that the synthesis of the minor transcripts depends on the box A- and B-like sequences, but does not depend on a TATA promoter element. Northern blot analysis indicated that the minor transcripts are only a few percent of the total transcripts derived from the aldolase B gene. Some of the minor transcripts analyzed were shown to have a mature size in the poly(A)+ RNA fraction. Thus, the minor transcripts of rat aldolase B gene are apparently transcribed by RNA polymerase III, and subsequently normally processed and polyadenylated. The possible function of these minor transcripts will be discussed.

Animals↗
PubMed1989

Restriction map and alpha-amylase activity variation among Drosophila mutation accumulation lines.

The specific activities of alpha-amylase were measured for two sets of mutation accumulation lines, each set having originated from a different lethal-carrying second chromosome and SM1(Cy) chromosome and having been maintained by a balanced lethal system for about 300 generations. Significant variation was found to have accumulated among lines of both sets. Because of dysgenic crosses in the early generations of mutation accumulation, insertions or deletions of transposable elements in the Amy gene region were suspected of being the cause of this variation. In order to test this possibility, the structural changes in the 14 kb region of these chromosomes that includes the structural genes for alpha-amylase were investigated by restriction map analysis. We found that most part of the activity variation is due to replacements of a chromosomal region of SM1(Cy), including the structural genes for alpha-amylase, by the corresponding regions of the lethal chromosomes. One line also contained an insertion in this region but this line has an intermediate activity value. Thus, insertions of transposable elements into the Amy gene region were not found to be responsible for the new variation observed in alpha-amylase activity. If we remove those lines with structural changes from the analysis, the genetic variance of alpha-amylase specific activity among lines becomes non-significant in both sets of chromosomes.

Animals↗