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N Satoh

Publications and source records attributed to N Satoh.

At least 19 recordsLinked to original sources
PubMed2006

Cloning and characterization of an ascidian homolog of the human 8-oxoguanine DNA glycosylase (Ogg1) that is involved in the repair of 8-oxo-7,8-dihydroguanine in DNA in Ciona intestinalis.

PURPOSE: It is of interest to perform a systematic comparative analysis of the conserved domains in DNA glycosylases and the evolution of DNA base excision repair systems. Furthermore, it is important to characterize the roles and regulation of base excision repair during the development of organisms. To address these issues, we first identified 8-oxo-7,8-dihydroguanine (8-oxoG)-DNA glycosylase (Ogg1) of the ascidian Ciona intestinalis as a good model system. MATERIALS AND METHODS: A cDNA clone coding for a peptide with homology to human Ogg1 was identified in the expressed sequence tag (EST) database from the Ciona cDNA resources. We examined whether CiOgg1 has DNA glycosylase/AP (apurinic/apyrimidinic) lyase activities for 8-oxoG-containing oligonucleotide. Furthermore, the expression level of CiOgg1 was compared in various tissues of Ciona intestinalis. RESULTS: The CiOgg1gene encoded a protein of 351 amino acids, which shows 37% identity of amino acid sequence with human Ogg1. The Helix-hairpin-Helix motif was highly conserved. The ascidian enzyme had functional 8-oxoG-DNA glycosylase/AP lyase activities, which removed 8-oxoG opposite cytosine from DNA. Expression of the CiOgg1 significantly reduced the frequency of spontaneous G:C to T:A transversions in E. coli mutM mutY. The highest expression level was observed in testis in Ciona intestinalis. CONCLUSIONS: The structure and functions of Ogg1 are well conserved in Ciona intestinalis. CiOgg1 is involved in the repair of 8-oxoG in DNA in Ciona intestinalis.

Amino Acid Sequence↗
PubMed2005

The cell death machinery controlled by Bax and Bcl-XL is evolutionarily conserved in Ciona intestinalis.

Bax and Bcl-XL are key regulators of apoptosis in mammals. Here we report the functional characterization of two Bcl-2 homologues, ciBax and ciBcl-XL, in a basal invertebrate-chordate ascidian Ciona intestinalis. CiBax is a Ciona homologue of the BH1-3 pro-apoptotic protein Bax, whereas ciBcl-XL is a Bcl-XL-like anti-apoptotic protein. Molecular modeling analysis showed that ciBax and ciBcl-XL share both sequence and structural similarities to human Bax and Bcl-XL, respectively. Like their human counterparts, ciBax could form a homodimer or oligomers as well as heterodimerize with ciBcl-XL, and overexpression of ciBax caused apoptosis that could be attenuated by ciBcl-XL. Mutagenesis studies showed that the BH3 domain of ciBax is critical for its cell death-inducing function and also for its interaction with ciBcl-XL. In Ciona embryos, ectopic expression of ciBax but not its BH3 deletion mutant resulted in cell dissociation and apoptosis after late gastrula stage of embryonic development. Moreover, not only wild type ciBcl-XL but also a mutant ciBcl-XL(F101V), which is unable to interact with ciBax, could block cell dissociation and developmental deficit in Ciona embryos induced by overexpression of ciBax. Taken together, these findings suggest that functional homologues of both the BH1-3 death effector Bax and the pro-survival Bcl-XL exist in sea squirt Ciona intestinalis, and they control the cell death machinery independent of their heterodimerization.

Animals↗
PubMed2005

A randomized double blind placebo-controlled clinical trial of Hochuekkito, a traditional herbal medicine, in the treatment of elderly patients with weakness N of one and responder restricted design.

OBJECTIVE: To evaluate the effects of Hochuekkito, a traditional Japanese and Chinese medicine, in the treatment of elderly patients with general weakness. To devise a suitable study design for assessing the clinical effectiveness of traditional herbal medicines. METHODS: Fifteen elderly patients (mean +/- SD: age 78.4 +/- 7.8; m/f 3/12) participated in this study. A multicenter, prospective, randomized, double-blind, placebo-controlled study with N of one and responder restricted design was performed. After the run-in period, the patients were divided into responders and non-responders. Only responders were entered in the study, and were randomized into three groups: an active-placebo group, a placebo-active group and an active-active group. The study consisted of two 6-week terms with a 2-week washout period in between. We assessed the Short Form 36 Health Survey (SF-36) and Profile of Mood States (POMS) as an endpoint of quality of life (QOL). In addition, we assessed the biodefense status by measuring the natural killer cytolytic activity (NK activity), IL-2 producing activity of peripheral lymphocytes, lymphocyte proliferating activity and lymphocyte cell-surface antigens. RESULTS: The physical component summary of the SF-36 analysis significantly improved in the Hochuekkito-treated group. Four components (A-H: anger-hostility, F: fatigue, T-A: tension-anxiety, C: confusion) out of six improved in the Hochuekkito-treated group in the POMS analysis. Lymphocyte proliferating activity improved in the Hochuekkito-treated group but not significantly. Concerning the surface antigens of peripheral lymphocytes, the population of CD3 positive cells and CD3CD4 double positive cells increased in the Hochuekkito-treated group. CONCLUSION: We revealed that Hochuekkito improved the QOL and immunological status of elderly patients with weakness by randomized controlled trial. Our study design might be useful for assessing the efficacy of traditional herbal medicine in the future.

Affect↗
PubMed2004

Buthionine sulfoximine inhibits cytopathic effect and apoptosis induced by infection with human echovirus 9.

We studied the effect of buthionine sulfoximine (BSO) on the replication of an isolate of human echovirus 9 (EV9) and the apoptosis induced by it in GMK cells. One hundred microM BSO markedly inhibited the cytopathic effect (CPE) induced by EV9. BSO also significantly inhibited apoptosis induced by EV9. BSO did not influence replication of EV9 genome, but inhibited virion formation. These results suggest that the inhibition by BSO of CPE and apoptosis induced by EV9 may be associated with the impairment of virion formation. Moreover, apoptosis induced by infections of human poliovirus 3, human coxsackievirus B5, A10 and A16, which, like EV9, belong to the genus Enterovirus, was markedly abolished by BSO. This finding suggests that enteroviral infections cause apoptosis through the activation of a common pathway that can be inhibited by BSO.

Animals↗
PubMed2003

Quantitation of bovine macrophage colony-stimulating factor in bovine serum by ELISA.

We established an enzyme-linked immunosorbent assay (ELISA) system for the quantitation of bovine macrophage colony-stimulating factor (M-CSF) and used it to measure the serum M-CSF levels in bovine fetuses and calves. The average serum M-CSF level was 2.7+/-1.5 ng/ml in 39 calves under 100 days old, and 1.8+/-0.8 ng/ml in 15 cattle between 101 and 418 days old. Fetal sera samples (n = 6) prepared from cattle between 150 and 280 days of gestational age had a higher average level of M-CSF (8.8+/-1.4 ng/ml). Alteration in serum M-CSF levels in each individual calf was also measured. The serum levels of M-CSF in calves at 0-1 day after birth ranged from 0.52 to 7.3 ng/ml. During the period 113-125 days after birth, serum levels were around 1.4+/-0.39 ng/ml. Although serum M-CSF levels generally decreased as the age of calves advanced, differences among individuals, especially among newborn calves, were observed.

Age Factors↗
PubMed2002

Further characterization of genes expressed during Ciona intestinalis metamorphosis.

Metamorphosis of ascidians is a dynamic event by which a nonfeeding, mobile tadpole larva is transformed into a filter-feeding, fixed juvenile. This process usually begins with the settlement of the larva and is followed by a series of coordinated morphogenetic movements that rearrange organs, tissues, and cells. To identify genes that are involved in the initiation of metamorphosis, we conducted differential screening between mRNAs of swimming larvae and those of juveniles in Ciona intestinalis. This screening permitted the isolation of cDNA clones for genes whose expression is upregulated during metamorphosis, and the characterization of four such genes (Ci-meta3, Ci-meta4, Ci-meta5 and Ci-meta6) is reported here. Ci-meta3 encodes a protein with a domain found in Sp1a and the RYanodine receptor. This gene is not expressed in early swimming larvae but is expressed in the endoderm region and part of the retractile tail region in metamorphosing juveniles. The predicted proteins encoded by Ci-meta4, Ci-meta5 and Ci-meta6 do not contain any known consensus motifs, nor do they show any similarity to known proteins. Ci-meta4 and Ci-meta5 are expressed weakly in mesenchyme cells of the early larva and strongly in the metamorphosing juvenile, while Ci-meta6 is expressed in the mesenchyme in the late larva. In addition, we characterized 53 independent cDNA clones whose expression was downregulated during the period from early swimming larvae to metamorphosing juveniles by taking advantage of the Ciona intestinalis cDNA project database and BLAST searches. The expression patterns of some of these clones were changed during the larval period.

Amino Acid Sequence↗
PubMed2001

Early development of amphioxus nervous system with special reference to segmental cell organization and putative sensory cell precursors: a study based on the expression of pan-neuronal marker gene Hu/elav.

The development of the nervous system of amphioxus was investigated at the cellular level based on the expression of the pan-neuronal marker gene Hu/elav. In situ hybridization analysis showed that an amphioxus Hu/elav homolog (AmphiHu/Hel) was expressed in individual cells within the neural plate, but the cells exhibited no obvious arrangements in early embryos without distinct somites. However, in neurulae with somites, AmphiHu/Hel-positive cells were clustered along the D-V axis in close register with the boundaries of somites, resulting in reiterated cell arrangements that became evident along the neuraxis. Furthermore, AmphiHu/Hel-positive cell clusters appeared one by one along with the development of underlying somites. Double-staining in situ hybridization analysis with the islet gene revealed that the cell clusters contain presumptive motoneurons. In addition, AmphiHu/Hel expression was also observed outside the CNS, probably in the epithelial ectoderm, suggesting that amphioxus has a large number of putative sensory cell precursors as early as the early neurula stage. Taking recent gene expression studies and anatomical studies into consideration, we discuss ontogenetic and phylogenetic features of the amphioxus nervous system.

Amino Acid Sequence↗
PubMed2001

Total synthesis of (+/-)-stemodinone via an efficient ring-exchange strategy.

A total synthesis of (+/-)-stemodinone, a tetracyclic stemodane diterpene, from the known tricyclic methyl olefin 11 is described. The key steps involve an efficient ring-exchange reaction and palladium(0)-catalyzed lactone migration. The ring-exchange strategy for controlling the stereochemistry was based on an initial Diels-Alder reaction to form a new ring followed by cleavage of the original ring. Cleavage of the original ring of the Diels-Alder adduct 9 was achieved by an initial regio- and chemoselective Baeyer-Villiger oxidation followed by the Pd(0)-catalyzed lactone-migration reaction reported by us.

Antiviral Agents↗
PubMed2001

Profiles of maternally expressed genes in fertilized eggs of Ciona intestinalis.

A set of 1,378 expressed sequence tags (ESTs), both the 5'-most and 3'-most ends, derived from Ciona intestinalis fertilized eggs was categorized into 1,003 independent clusters. When compared with sequences in databases, 452 of the clusters showed significant matches with reported proteins, while 190 showed matches with putative proteins for which there is not enough information to categorize their function, and 361 had no significant similarities to known proteins. Sequence similarity analyses of the 452 clusters in relation to the biological function as well as the structure of the message population at this stage demonstrated that 362 of them have functions that many kinds of cells use, 65 are associated with cell-cell communication, including a candidate cDNA for sonic hedgehog, and 25 are transcription factors. Sequence prevalence distribution analysis demonstrated that the great majority (78%) of the mRNAs are rare mRNAs or are represented by a single clone/cluster. All of the 1,003 clusters were subjected to whole-mount in situ hybridization to analyze the distribution of the maternal mRNAs in fertilized eggs, and a total of 329 genes showed localized distribution of the mRNAs: 16 showed cortical localization, 12 showed mitochondrial-like distribution, 99 crescent-like distribution, 63 partial localization, and 139 weak localization. When the distribution pattern of all the maternally expressed mRNAs was examined in the 8-cell stage embryos, it became evident that 248 genes which have localized mRNA patterns at the fertilized egg stage lose their localized distribution by the 8-cell stage. In contrast, 13 genes newly gain a localized pattern by the 8-cell stage. In addition, a total of 39 genes showed distinct in situ signals in the nucleus of blastomeres of the 8-cell stage embryo, suggesting early zygotic expression of these genes by this stage. These results suggest that complicated cytoplasmic movements are associated with the characteristic distribution of maternal mRNAs, which in turn support proper embryonic axis formation and establishment of the genetic network for embryonic cell specification.

Animals↗
PubMed2001

Ci-opsin1, a vertebrate-type opsin gene, expressed in the larval ocellus of the ascidian Ciona intestinalis.

A novel gene encoding visual pigment, Ci-opsin1, was identified in a primitive chordate, the ascidian, Ciona intestinalis. Molecular phylogenetic analysis and the exon-intron organization suggest that Ci-opsin1 is closely related to the retinal and pineal opsins of vertebrates. During embryogenesis, Ci-opsin1 transcripts were first detected in part of the brain of mid tailbud embryos; its expression was confined to photoreceptor cells of the ocellus (eye spot) in the larval brain as development proceeded. These results suggest a common descent of the ascidian ocellus and the vertebrate eyes. The ocellus of ascidian larvae may represent an ancestral state of the vertebrate eye.

Amino Acid Sequence↗
PubMed2001

Change in spin state and enhancement of redox reactivity of photoexcited states of aromatic carbonyl compounds by complexation with metal ion salts acting as Lewis acids. Lewis acid-catalyzed photoaddition of benzyltrimethylsilane and tetramethyltin via photoinduced electron transfer.

The lowest excited state of aromatic carbonyl compounds (naphthaldehydes, acetonaphthones, and 10-methylacridone) is changed from the n,pi triplet to the pi,pi singlet which becomes lower in energy than the n,pi triplet by the complexation with metal ions such as Mg(ClO(4))(2) and Sc(OTf)(3) (OTf = triflate), which act as Lewis acids. Remarkable positive shifts of the one-electron reduction potentials of the singlet excited states of the Lewis acid-carbonyl complexes (e.g., 1.3 V for the 1-naphthaldehyde-Sc(OTf)(3) complex) as compared to those of the triplet excited states of uncomplexed carbonyl compounds result in a significant increase in the redox reactivity of the Lewis acid complexes vs uncomplexed carbonyl compounds in the photoinduced electron-transfer reactions. Such enhancement of the redox reactivity of the Lewis acid complexes leads to the efficient C-C bond formation between benzyltrimethylsilane and aromatic carbonyl compounds via the Lewis-acid-promoted photoinduced electron transfer. The quantum yield determinations, the fluorescence quenching, and direct detection of the reaction intermediates by means of laser flash photolysis experiments indicate that the Lewis acid-catalyzed photoaddition reactions proceed via photoinduced electron transfer from benzyltrimethylsilane to the singlet excited states of Lewis acid-carbonyl complexes.

Journal Article↗
PubMed2001

Stabilization factors affecting duplex formation of peptide nucleic acid with DNA.

Peptide nucleic acid (PNA) is an oligonucleotide analogue in which the sugar-phosphate backbone is replaced by an N-(2-aminoethyl)glycine unit to which the nucleobases are attached. We investigated the thermodynamic behavior of PNA/DNA hybrid duplexes with identical nearest neighbors but with different sequences and chain lengths (5, 6, 7, 8, 10, 12, and 16 mers) to reveal whether the nearest-neighbor model is valid for the PNA/DNA duplex stability. CD spectra of 6, 7, and 8 mer PNA/DNA duplexes showed similar signal, while 10, 12, and 16 mer duplexes did not. The average difference in Delta G degrees (37) for short PNA/DNA duplexes with identical nearest-neighbor pairs was only 3.5%, whereas that of longer duplexes (10, 12, and 16 mers) was 16.4%. Therefore, the nearest-neighbor model seems to be useful at least for the short PNA/DNA duplexes. Thermodynamics of PNA/DNA duplexes containing 1--3 bulge residues were also studied. While the stability of the 12 mer DNA/DNA duplex decreased as the number of bulge bases increases, the number of bulge bases in PNA/DNA unchanged the duplex stability. Thus, the influence of bulge insertion in the PNA/DNA duplexes is different from that of a DNA/DNA duplex. This might be due to the different base geometry in a helix which may potentially make hydrogen bonds in a base pair and stacking interaction unfavorable compared with DNA/DNA duplexes.

Base Composition↗
PubMed2001

Total synthesis of (+/-)-scopadulin.

The first total synthesis of (+/-)-scopadulin, an aphidicolane diterpene, is described. The core structure (A/B/C/D ring system) was constructed by an initial synthesis of the B/C/D ring system by our reported methods and a subsequent A ring cyclization by intramolecular aldol condensation. A highly stereoselective cyanation of the tetracyclic enone by Et2AlCN gave a trans-fused A/B ring system with a beta-cyanide at C-4. Stereoselective construction of a quaternary carbon at C-4 was achieved by alpha-alkylation of the cyano group and conversion of the sterically hindered cyano group to a methyl group via our novel reaction for conversion of primary aliphatic amines into alcohols. Finally, the total synthesis of (+/-)-scopadulin was accomplished by a highly chemo- and stereoselective methylation at C-16 and modification of the C-4 alpha-functionality. The stereoselectivity observed in the MeTi(O-i-Pr)3-mediated methylation for the generation of a tertiary axial alcohol at C-16 is extremely high.

Antiviral Agents↗
PubMed2001

The first total synthesis of (+/-)-scopadulin, an antiviral aphidicolane diterpene.

[reaction: see text] The first total synthesis of (+/-)-scopadulin was accomplished by a stereoselective construction of a quaternary carbon at C-4, conversion of the hindered cyano group to a methyl group via our novel reaction for conversion of primary aliphatic amines into alcohols, and a highly chemo- and stereoselective methylation at C-16.

Antiviral Agents↗
PubMed2001

The simple tail of chordates: phylogenetic significance of appendicularians.

Appendicularia comprises a group of pelagic tunicates that retain the tail throughout their life without exhibiting the drastic metamorphosis seen in ascidians or doliolids. They are known to possess a simple body architecture that is comparable with that of other chordates. Recent phylogenetic studies suggest that appendicularians represent a sister group of the clade of other tunicates. Very recently, two independent research groups reported molecular-based approaches to the appendicularian development. We review here some general descriptions and results of recent analyses on the anatomy and developmental biology of appendicularians, focusing upon their simple tail architecture. We emphasize future possibilities for a comprehensive understanding of the divergent patterns in lifestyle of tunicates as well as for investigating the phylogenetic novelty and innovation of chordates such as the tail.

Animals↗
PubMed2001

Expression of thyroid transcription factor-1 (TTF-1) gene in the ventral forebrain and endostyle of the agnathan vertebrate, Lampetra japonica.

The Thyroid transcription factor-1 (TTF-1) gene belongs to the Nkx-2.1 subfamily and encodes a transcription factor containing an NK-2-type homeodomain. In our study, we isolated and characterized cDNA clones for the TTF-1/Nkx-2.1 orthologue (LjTTF-1) from the agnathan vertebrate Lampetra japonica. Spatial and temporal expression patterns assessed by in situ hybridization revealed the expression of LjTTF-1 in the anterior nerve cord and anteroventral region of the pharynx. The neural expression was subsequently restricted to the ventral diencephalon. The pharyngeal expression, on the other hand, extended posteriorly to the fourth pharyngeal-pouch level and was finally localized in the endostyle anlage. In the differentiated endostyle of ammocoete larvae, the expression of LjTTF-1 was chiefly detected in type 2a, 2b, and 2c cells, which develop adjacent to glandular cells. These expression patterns of LjTTF-1 support the idea that this gene family plays an important role in the development of the rostral brain and endostyle equivalent organs. Furthermore, histological comparisons between TTF-1/Nkx-2.1 expression in the endostyles of ammocoetes and ascidians suggested the possibility that the organogenetic architecture of the endostyle is conserved among chordates.

Amino Acid Sequence↗
PubMed2001

Action of morpholinos in Ciona embryos.

First, using morpholino against lacZ, we demonstrate that the morpholino specifically suppresses the translation of the gene introduced exogenously into Ciona eggs. Second, using morpholino against an alkaline phosphatase gene, we show that the morpholino suppresses the translation of the endogenous gene as well. Third, using morpholino against beta-catenin gene, we confirm that the suppression by the morpholino can be rescued by injection of beta-catenin mRNA. All of these results indicate that morpholino act in Ciona embryos to specifically block the function of endogenous genes as well as exogenously introduced genes. genesis 30: 103--106, 2001.

Animals↗