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A Isogai

Publications and source records attributed to A Isogai.

At least 37 records · Page 2Linked to original sources
PubMed2000

Alteration of the self-incompatibility phenotype in Brassica by transformation of the antisense SLG gene.

Self-incompatible (SI) Brassica rapa (syn. B. campestris) was transformed with an antisense SLG gene by using SLG8 cDNA isolated from the B. campestris S8 homozygote. Two transformed lines were obtained and analyzed. Northern blot and Western blot analyses revealed that endogenous SLG and SRK were greatly reduced of the transcriptional and translational levels in the transformant. Pollination experiments confirmed that their SI phenotype had broken down. In addition, the progeny with the antisense SLG gene, resulting from self- or cross-pollination of the transgenic plant, also showed the self-compatible phenotype. The breakdown of SI in the tranformants was due to the change in property of the stigma and not of the pollen. These results provide strong evidence that SLG and/or SRK is implicated in the pollen-stigma recognition of SI and that they act only as stigmatic factors.

Brassica↗
PubMed2000

Blasticidin A as an inhibitor of aflatoxin production by Aspergillus parasiticus.

Blasticidin A, an antibiotic, showed strong inhibitory activity toward aflatoxin production by Aspergillus parasiticus. Its structure was characterized by NMR and chemical degradation experiments as 1, which is a tetramic acid derivative with a highly oxygenated long alkyl chain similar to aflastatin A (2). Absolute configurations of the eight chiral centers at C-4, 6, 31, 32, 33, 34, 35 and 37 of 1 were chemically determined. Blasticidin A almost completely inhibited aflatoxin production at 0.5 microM.

Aflatoxins↗
PubMed2000

[Continuous hepatic arterial infusion of 5-fluorouracil with leucovorin for unresectable liver metastases from colorectal cancer].

Twenty-three patients with liver metastases from colorectal cancer were treated by continuous hepatic arterial infusion chemotherapy with 5-FU and Leucovorin. The regimen was that 500 mg/body of 5-FU with 30 mg/body of Leucovorin was administered continuously for 5 days, followed by no medication for 16 days. The effect of this therapy was evaluated and the relationship between this therapy and the overexpression of vascular endothelial growth factor (VEGF) or microvessel density (MVD) was also studied. Complete response was obtained in 4 patients and partial response in 3 patients; the response rate was 32%. The response rate was 60% in patients who underwent more than 7 courses. The response rate was 44% in patients with positive VEGF and 33% in patients with negative VEGF. The response rate was 50% in patients with an MVD of more than 30 and 33% in patients with an MVD of less than 30. The 3-year survival rate for patients who underwent more than 7 courses was 37.5%. This therapy had to be abandoned in 6 patients due to occlusion of the catheter. Skillful maintenance of the catheter is necessary for a high response rate and satisfactory prognosis using this therapy.

Aged↗
PubMed1999

Prothoracicotropic activity of SBRPs, the insulin-like peptides of the saturniid silkworm Samia cynthia ricini.

Synthesis and secretion of the insect molting hormone ecdysteroid in the prothoracic glands (PGs) are stimulated by the prothoracicotropic hormone (PTTH) secreted by the brain. Bombyxins, insulin-like peptides of the silkworm Bombyx mori, show prothoracicotropic activity when administered to the saturniid silkworm Samia cynthia ricini, but they are inactive to B. mori itself. Recently, the genes for the bombyxin homologs of S. cynthia ricini (referred to as Samia bombyxin-related peptides, SBRPs) were cloned. To examine the prothoracicotropic activity of SBRPs on S. cynthia ricini, we synthesized two representative molecules, SBRP-A1 and -B1. They promoted pupa-to-adult development with ED(50) of 50 and 10 ng/pupa (EC(50) of 5 and 1 nM), respectively.

Amino Acid Sequence↗
PubMed1999

Introduction of SLG (S locus glycoprotein) alters the phenotype of endogenous S haplotype, but confers no new S haplotype specificity in Brassica rapa L.

Self-incompatibility (SI) in Brassicaceae is genetically controlled by the S locus complex in which S locus glycoprotein (SLG) and S receptor kinase (SRK) genes have been identified, and these two genes encoding stigma proteins are believed to play important roles in SI recognition reaction. Here we introduced the SLG43 gene of Brassica rapa into a self-incompatible cultivar, Osome, of B. rapa, and examined the effect of this transgene on the SI behavior of the transgenic plants. Preliminary pollination experiments demonstrated that Osome carried S52 and S60, and both were codominant in stigma, but S52 was dominant to S60 in pollen. S43 was found to be recessive to S52 and codominant with S60 in stigma. The nucleotide sequence of SLG43 was more similar to that of SLG52 (87.8% identity) than to that of SLG60 (74.8% identity). Three of the ten primary transformants (designated No. 1 to No. 10) were either completely (No. 9) or partially (No. 6 and No. 7) self-compatible; the SI phenotype of the stigma was changed from S52S60 to S60, but the SI phenotype of the pollen was not altered. In these three plants, the mRNA and protein levels of both SLG43 and SLG52 were reduced, whereas those of SLG60 were not. All the plants in the selfed progeny of No. 9 and No. 6 regained SI and they produced a normal level of SLG52. These results suggest that the alteration of the SI phenotype of the stigma in the transformants Nos. 6, 7, and 9 was the result of specific co-suppression between the SLG43 transgene and the endogenous SLG52 gene. Three of the transformants (Nos. 5, 8 and 10) produced SLG43 protein, but their SI phenotype was not altered. The S60 homozygotes in the selfed progeny of No. 10 which produced the highest level of SLG43 were studied because S43 was codominant with S60 in the stigma. They produced SLG43 at approximately the same level as did S43S60 heterozygotes, but did not show S43 haplotype specificity at the stigma side. We conclude that SLG is necessary for the expression of the S haplotype specificity in the stigma but the introduction of SLG alone is not sufficient for conferring a novel S haplotype specificity to the stigma.

Blotting, Southern↗
PubMed1999

Genomic organization of the S locus: Identification and characterization of genes in SLG/SRK region of S(9) haplotype of Brassica campestris (syn. rapa).

In Brassica, two self-incompatibility genes, encoding SLG (S locus glycoprotein) and SRK (S-receptor kinase), are located at the S locus and expressed in the stigma. Recent molecular analysis has revealed that the S locus is highly polymorphic and contains several genes, i.e., SLG, SRK, the as-yet-unidentified pollen S gene(s), and other linked genes. In the present study, we searched for expressed sequences in a 76-kb SLG/SRK region of the S(9) haplotype of Brassica campestris (syn. rapa) and identified 10 genes in addition to the four previously identified (SLG(9), SRK(9), SAE1, and SLL2) in this haplotype. This gene density (1 gene/5.4 kb) suggests that the S locus is embedded in a gene-rich region of the genome. The average G + C content in this region is 32.6%. An En/Spm-type transposon-like element was found downstream of SLG(9). Among the genes we identified that had not previously been found to be linked to the S locus were genes encoding a small cysteine-rich protein, a J-domain protein, and an antisilencing protein (ASF1) homologue. The small cysteine-rich protein was similar to a pollen coat protein, named PCP-A1, which had previously been shown to bind SLG.

Amino Acid Sequence↗
PubMed1999

Relationship between polyploidy and pollen self-incompatibility phenotype in Petunia hybrida Vilm.

Self-incompatibility in Solanaceae is controlled by a single multiallelic locus, the S-locus. The S-allele associated ribonucleases (S-RNases) in the pistil are involved in pollen rejection. In this work, we analyzed two newly isolated lines of Petunia hybrida, termed PB and PF. They both had the same set of S-RNases (SB1- and SB2-RNases), however the PB was a self-incompatible diploid while PF was a self-compatible tetraploid. Cross pollination tests between PB and PF indicated diploid pollen from PF lost the incompatibility phenotype. In order to clarify the effects of polyploidy on pollen phenotypic change, we artificially induced tetraploid plants from a diploid SB1SB2 heterozygote (= PB) and a diploid SB1SB1 homozygote. The obtained SB1 SB1SB1SB1 homoallelic tetraploid remained self-incompatible, whereas the SB1SB1SB2SB2 heteroallelic tetraploid became self-compatible. These data suggested that the diploid heteroallelic pollen lost the incompatibility phenotype and had the characteristics of self-compatibility with SB1SB2 style.

Alleles↗
PubMed1998

Molecular characterization of photomixotrophic tobacco cells resistant to protoporphyrinogen oxidase-inhibiting herbicides

Peroxidizing herbicides inhibit protoporphyrinogen oxidase (Protox), the last enzyme of the common branch of the chlorophyll- and heme-synthesis pathways. There are two isoenzymes of Protox, one of which is located in the plastid and the other in the mitochondria. Sequence analysis of the cloned Protox cDNAs showed that the deduced amino acid sequences of plastidial and mitochondrial Protox in wild-type cells and in herbicide-resistant YZI-1S cells are the same. The level of plastidial Protox mRNA was the same in both wild-type and YZI-1S cells, whereas the level of mitochondrial Protox mRNA YZI-1S cells was up to 10 times the level of wild-type cells. Wild-type cells were observed by fluorescence microscopy to emit strong autofluorescence from chlorophyll. Only a weak fluorescence signal was observed from chlorophyll in YZI-1S cells grown in the Protox inhibitor N-(4-chloro-2-fluoro-5-propagyloxy)-phenyl-3,4,5, 6-tetrahydrophthalimide. Staining with DiOC6 showed no visible difference in the number or strength of fluorescence between wild-type and YZI-1S mitochondria. Electron micrography of YZI-1S cells showed that, in contrast to wild-type cells, the chloroplasts of YZI-1S cells grown in the presence of N-(4-chloro-2-fluoro-5-propagyloxy)-phenyl-3,4,5, 6-tetrahydrophthalimide exhibited no grana stacking. These results suggest that the herbicide resistance of YZI-1S cells is due to the overproduction of mitochondrial Protox.

Journal Article↗
PubMed1998

Structures and biosynthesis of aflastatins: novel inhibitors of aflatoxin production by Aspergillus parasiticus.

Two novel inhibitors of aflatoxin production by Aspergillus parasiticus were isolated from the mycelial extracts of Streptomyces sp. MRI142 and termed aflastatin A and B. The structures of aflastatin A (1) and B (5) were elucidated by NMR and chemical degradation experiments. These compounds have a novel skeleton of a tetramic acid derivative with a highly oxygenated long alkyl chain. The incorporation experiments using 13C-labeled acetates, propionate, glucose and glycolate suggested that most of the C2 and C3 units involved in the alkyl chain moiety of aflastatin A were biosynthesized from acetic and propionic acids, but five C2 units in the alkyl chain originated from glycolic acid.

Aflatoxins↗
PubMed1997

Direct cloning of the Brassica S locus by using a P1-derived artificial chromosome (PAC) vector.

Self-incompatibility of Brassica is regulated by the S locus, which contains several genes including SLG and SRK. We found that both SLG and SRK genes were located at an approx. 80-kb MluI fragment in an S9 haplotype of B. campestris. Therefore, we cloned this MluI fragment into a BssHII site of the P1-derived artificial chromosome (PAC) vector. The utility of the direct cloning method is discussed in this study.

Bacteria↗
PubMed1997

Highly conserved 5'-flanking regions of two self-incompatibility genes, SLG9 and SRK9.

The nucleotide (nt) sequences of the 5'-flanking regions of two Brassica self-incompatibility genes, SLG9 and SRK9, were determined. Their sequences were highly conserved: a region spanning 1.9 kb in the 5'-flanking region was completely identical except for a 1319-bp segment in SLG9. These observations strongly suggest that SLG9 and SRK9 together with their promoter regions were involved in a gene duplication or conversion event which occurred before the 1319-bp SLG9-specific sequence was inserted in SLG9 or deleted in SRK9.

Base Sequence↗
PubMed1997

Three members of the S multigene family are linked to the S locus of Brassica.

Two self-incompatibility genes in Brassica, SLG and SRK (SLG encodes a glycoprotein; SRK encodes a receptor-like kinase), are included in the S multigene family. Products of members of the S multigene family have an SLG-like domain (S domain) in common, which may function as a receptor. In this study, three clustered members of the S multigene family, BcRK1, BcRL1 and BcSL1, were characterized. BcRK1 is a putative functional receptor kinase gene expressed in leaves, flower buds and stigmas, while BcRL1 and BcSL1 are considered to be pseudogenes because deletions causing frameshifts were identified in these sequences. Sequence and expression pattern of BcRK1 were most similar to those of the Arabidopsis receptor-like kinase gene ARK1, indicating that BcRK1 might have a function similar to that of ARK1, in processes such as cell expansion or plant growth. Interestingly, the region containing BcRK1, BcRL1 and BcSL1 is genetically linked to the S locus and the physical distance between SLG, SRK and the three S-related genes was estimated to be less than 610 kb. Thus the genes associated with self-incompatibility exist within a cluster of S-like genes in the genome of Brassica.

Amino Acid Sequence↗
PubMed1997

Globular and fibrous structure in barley chromosomes revealed by high-resolution scanning electron microscopy.

Barley chromosomes were prepared for high-resolution scanning electron microscopy using a combination of enzyme maceration, treatment in acetic acid and osmium impregnation using thiocarbohydrazide. Using this technique, the three-dimensional ultrastructure of interphase nuclei and mitotic chromosomes was examined. In Interphase, different levels of chromatin condensation were observed, consisting of fibrils 10 nm in diameter, 20- to 40-nm fibres and a higher order complex. In prophase, globular and strand-like structures composed of 20- to 40-nm fibres were dominant. As the cells progressed through the cell cycle and the chromatin condensed, globular and strand-like structures (chromomeres) were coiled and packed to form chromosomes. Chromomeres were observed as globular protuberances on the surface of metaphase chromosomes. These findings indicate that the chromomere is a fundamental substructure of the higher order architecture of the chromosome. In the centromeric region, there were no globular protuberances, but 20- to 40-nm fibres were folded compactly to form a higher level organization surrounding the chromosomal axia.

Chromatin↗
PubMed1997

The cessation of fluoridated water administration and the fluoride distribution profiles in rat molar cementum.

The aim of this work was to obtain further information about the origin of fluoride profiles in cementum. Fluoride was administered to rats at varying doses (0.50, 100 ppm F in drinking water) and for different durations (4, 13 and 25 weeks). Fluoride distribution across the full thickness of molar cementum in rats was measured by means of an abrasive micro-sampling technique. The average fluoride concentrations in cementum increased significantly with increasing dose and duration of fluoride administration. The relative reduction of the average fluoride concentrations after cessation of fluoride administration was 94.2-36.5% at 50 ppm F and 62.2-49.2% at 100 ppm F in the outer layers (1-60 microns) and 91.5-24.1% at 50 ppm F and 74.1-7.6% at 100 ppm F in the middle (61-120 microns) layers of the cementum, respectively. The reduction rates were more closely related to the time intervals following cessation rather than fluoride concentrations in drinking water or specificity within the cementum. Two factors which may influence this are new cementum formation after withdrawal of fluoride and some fluoride release from cementum surfaces when the fluoride supply stopped. It was concluded that the cessation of fluoride administration reduced the fluoride concentration on the outer layers of cementum differing from bone where reduction occurs across the entire thickness.

Analysis of Variance↗
PubMed1997

Molecular cloning of a new type of cDNA for pheromone biosynthesis activating neuropeptide in the silkworm, Bombyx mori.

A neuropeptide named pheromone biosynthesis activating neuropeptide (PBAN) stimulates the pheromone production of lepidopteran insects. We have identified a different type of cDNA for PBAN, which shows two amino acid replacements in the region of the PBAN sequence previously reported. Single strand conformation polymorphism (SSCP) analysis revealed that the two types of cDNA originated from two allelic variants of the gene for PBAN.

Alleles↗
PubMed1997

Aflastatin A, a novel inhibitor of aflatoxin production by aflatoxigenic fungi.

Aflastatin A, a novel inhibitor of the production of aflatoxin by aflatoxigenic fungi, has been isolated from the solvent extract of mycelial cake of Streptomyces sp. and its molecular formula was determined as C62H115NO24. Aflastatin A completely inhibited aflatoxin production by Aspergillus parasiticus NRRL 2999 in liquid medium or on agar plate at a concentration of 0.5 microgram/ml. The mycelial growth of this fungus was not affected in the liquid medium at the same concentration, while the hyphal extension rate was reduced on the plate together with some morphological changes. The growth of the fungus was not completely inhibited even at a concentration of 100 micrograms/ml. Aflastatin A exhibits antimicrobial activity against some bacteria, yeasts and fungi as well as antitumor activity.

Aflatoxins↗
PubMed1996

Primary structures of fungal fructosyl amino acid oxidases and their application to the measurement of glycated proteins.

Fructosyl amino acid oxidase (FAOD), which is active toward model compounds of the glycated proteins in blood, N epsilon-fructosyl N sigma-Z-lysine and N-fructosyl valine, was purified to homogeneity from Aspergillus terreus GP1. Though the enzyme did not use glycated proteins directly as its substrate, it used glycated human serum albumin (HSA) when HSA was treated with a protease. Linear relationships between both the concentration and the increase in absorbance and the glycation rate of glycated HSA and the increase in absorbance were observed. cDNAs coding for FAODs were cloned from cDNA libraries of A. terreus GP1 and Penicillium janthinellum AKU 3413. The coding region for both fungal FAODs consisted of 1314 bp encoding 437 amino acids. The sequence of a dinucleotide-binding motif, GXGXXG, was in the deduced N-terminal region and a similar sequence to that the active site of bacterial sarcosine oxidases was found near the C-terminal region of FAOD. The of C-terminal tripeptides SKL and AKL of FAODs from A. terreus and P. janthinellum, respectively, represent typical peroxisomal-targeting signals. Finally, FAOD protein was produced in Escherichia coli transformants in an active form, and at the same level as in the original fungi.

Amino Acid Oxidoreductases↗