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Y Satou

Publications and source records attributed to Y Satou.

At least 19 recordsLinked to original sources
PubMed2006

Spin correlations of strongly interacting massive fermion pairs as a test of Bell's inequality.

We report the results of the first-time test of the local hidden variable theories (Bell-Clauser-Horne-Shimony-Holt) involving strongly interacting pairs of massive spin 1/2 hadrons from the decay of short-lived (tau<10;-21sec) 2He spin-singlet state, populated in the nuclear reaction 2H+;1H-->;2He+n. The novel features of this experiment are (a) the use of an 'event-ready' [corrected] detector of nearly 100% efficiency to prepare an unbiased sample and (b) a focal-plane polarimeter of full 2pi sr acceptance with a random "post selection" of the reference axes. The spin-correlation function is deduced to be S[exp](pi/4)=2.83+/-0.24stat+/-0.07sys. This result is in agreement with nonlocal quantum mechanical prediction and it violates the Bell-CHSH inequality of |S|<or=2 at a confidence level of 99.3%.

Journal Article↗
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↗
PubMed2006

Relationship between the growth pattern of nasopharyngeal cancer and the cervical lymph nodes based on MRI findings: can the cervical radiation field be reduced in patients with nasopharyngeal cancer?

To identify patients with nasopharyngeal cancer in whom the cervical radiation field can be reduced, we classified the growth patterns of nasopharyngeal cancer based on MRI findings into 4 types and performed an evaluation. Based on MRI findings, we classified the growth patterns of primary cancer in 94 patients with nasopharyngeal cancer into Type 1 (superficial type), Type 2 (lateral invasive type), Type 3 (upward invasive type), and Type 4 (anterior extension type), and further classified Type 2, based upon nasopharyngoscopic findings, into Type 2a (unilateral invasive type) and Type 2b (bilateral invasive type). The cervical lymph node metastasis areas were evaluated according to these types. Type 2 showed a significantly higher incidence of cervical lymph node metastasis only on the ipsilateral side than the other types (p = 0.0024). In particular, all patients with Type 2a had cervical lymph node metastasis only on the ipsilateral side (p = 0.0212). This study suggests that the distribution of metastasised cervical lymph nodes depends on the pattern of tumour extent of the primary site.

Adolescent↗
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↗
PubMed2004

Proteasome inhibitor, bortezomib, potently inhibits the growth of adult T-cell leukemia cells both in vivo and in vitro.

Adult T-cell leukemia (ATL) is a fatal neoplasm derived from CD4-positive T-lymphocytes, and regardless of intensive chemotherapy, its mean survival time is less than 1 year. Nuclear factor-kappaB (NF-kappaB) activation was reported in HTLV-I associated cells, and has been implicated in oncogenesis and resistance to anticancer agents and apoptosis. We studied the effect of a proteasome inhibitor, bortezomib (formerly known as PS-341), on ATL cells in vitro and in vivo. Bortezomib could inhibit the degradation of IkappaBalpha in ATL cells, resulting in suppression of NF-kappaB and induction of cell death in ATL cells in vitro. Susceptibilities to bortezomib were well correlated with NF-kappaB activation, suggesting that suppression of the NF-kappaB pathway was implicated in the cell death induced by bortezomib. Although the majority of the cell death was apoptosis, necrotic cell death was observed in the presence of a caspase inhibitor, z-VAD-fmk. When bortezomib was administered into SCID mice bearing tumors, it suppressed tumor growth in vivo, showing that bortezomib was effective against ATL cells in vivo. These studies revealed that bortezomib is highly effective against ATL cells in vitro and in vivo by induction of apoptosis, and its clinical application might improve the prognosis of patients with this fatal disease.

Animals↗
PubMed2002

Isovector quadrupole resonance observed in the 60Ni(13C,13N)60Co reaction at E/A=100 MeV.

The charge-exchange reaction 60Ni(13C,13N)60Co at E/A=100 MeV has been studied to locate isovector (deltaT=1) non-spin-flip (deltaS=0) giant resonances. Besides the giant dipole resonance at E(x)=8.7 MeV, another resonance has been observed at E(x)=20 MeV with a width of 9 MeV. Distorted-wave Born approximation analysis on the angular distribution clearly indicated the L=2 multipolarity, attributing the E(x)=20 MeV state to the giant isovector quadrupole resonance.

Journal Article↗
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

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

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↗
PubMed2001

Isolation and characterization of genes that are expressed during Ciona intestinalis metamorphosis.

In ascidians, the events of metamorphosis transform the non-feeding, mobile tadpole larva into a filter-feeding, fixed juvenile, and the process involves rearrangements of cells, two organs and physiological changes. Differential screening was used to isolate two genes that are not expressed in swimming larvae but are expressed immediately after the initiation of metamorphosis in Ciona intestinalis. One of the genes, Ci-meta1, encodes a polypeptide with a putative secretion signal sequence, 6 epidermal growth factor (EGF)-like repeats and 13 calcium-binding EGF-like repeats. The gene begins to be expressed immediately after the beginning of metamorphosis in the adhesive organ and is likely to be associated with the signal response for metamorphosis. Another gene named Ci-meta2 encodes a protein with a putative secretion signal and three thrombospondin type-1 repeats. Ci-meta2 gene expression begins at the larval stage and is upregulated in the metamorphosing juveniles. Ci-meta2 expression is found in three regions; the adhesive organ which is also associated with settlement, the neck region between the trunk and the tail of the larva which is associated with tail resorption, and dorsal regions of the trunk which correspond to the location of the siphon primordium. This gene may be involved in the dynamic arrangement of cells during ascidian metamorphosis.

Amino Acid Sequence↗
PubMed2001

Brachyury (T) gene expression and notochord development in Oikopleura longicauda (Appendicularia, Urochordata).

Appendicularia (Larvacea) is a subgroup of Urochordata (Tunicata) comprised of holoplanktonic organisms that retain their tailed architecture throughout their life history, while other tunicates, including ascidians and doliolids, resorb the tail after metamorphosis. In order to investigate the characteristics of the appendicularian unresorbed notochord, we isolated a partial genomic clone and a full-length cDNA sequence homologous to the mouse Brachyury (T) gene from the appendicularian Oikopleura longicauda. Brachyury is known to be predominantly expressed in the notochord cells and plays an important role in their differentiation in other chordates. While phylogenetic analysis robustly supports the orthology of the isolated Brachyury gene, the exon-intron organization found in the genomic clone was distinct from that well-conserved among other T-box genes. In addition to a detailed observation of notochord development in living specimens, whole-mount double in situ hybridization was carried out using a Brachyury probe along with a muscle actin probe. The Brachyury transcripts were found in the notochord of the tailbud embryos and persisted into later stages. The present study highlights characteristics of notochord development in the appendicularian. Furthermore, these results provide basic knowledge for comprehensive understanding of the cellular- and molecular-based mechanisms needed to build the characteristic cytoarchitecture of notochord that varies among tunicate species.

Amino Acid Sequence↗
PubMed2001

Condylar bony change and self-reported parafunctional habits in prospective orthognathic surgery patients with temporomandibular disorders.

OBJECTIVE: The purpose of this study was to investigate the relationship between self-reported parafunctional habits and condylar bony change and disk displacement in orthognathic surgery patients with signs and symptoms of temporomandibular joint disorders. STUDY DESIGN: This is a cross-sectional retrospective study of pretreatment helical computed tomography scans and questionnaires of 94 female orthognathic surgery patients. RESULTS: Condylar bony change, unilaterally or bilaterally, was found in 56.4% of the subjects, or 43.6% of the joints. Disk displacement, unilaterally or bilaterally, was seen in 59.6% of the subjects, or 45.7% of the joints. Bruxism and clenching was significantly associated with condylar bony change and disk displacement. Subjects with 3 or more parafunctional habits showed a significantly higher rate of bilateral condylar bony change. CONCLUSION: Our results suggest that bruxism and clenching might be related to deterioration of the temporomandibular joint and that the greater the number of parafunctional habits a subject has, the higher the risk of condylar bony change.

Bruxism↗
PubMed2001

A case of anterior open bite developing during adolescence.

Imaging studies have reported on the relationship between temporomandibular joint (TMJ) degeneration and facial deformity. These studies have suggested that mandibular growth is affected by TMJ degeneration, resulting in altered skeletal structure as mandibular retrusion. However, there are very few longitudinal case reports on TMJ osteoarthrosis (OA). Progressive open bite occurred in an adolescent patient with TMJ OA. Cephalometric analysis showed a downward and backward rotated mandible, and a labial inclination of the upper incisor. Magnetic resonance imaging showed internal derangement without reduction and erosion in the right and the left condyles. Although the cause of open bite is unclear in this case, tongue thrusting, and internal derangements in the temporomandibular joint were suspected as causes of the open bite.

Bone Resorption↗
PubMed2001

Gene expression profiles in Ciona intestinalis tailbud embryos.

A set of 3423 expressed sequence tags derived from the Ciona intestinalis tailbud embryos was categorized into 1213 independent clusters. When compared with DNA Data Bank of Japan database, 502 clusters of them showed significant matches to reported proteins with distinct function, whereas 184 lacked sufficient information to be categorized (including reported proteins with undefined function) and 527 had no significant similarities to known proteins. Sequence similarity analyses of the 502 clusters in relation to the biosynthetic function, as well as the structure of the message population at this stage, demonstrated that 390 of them were associated with functions that many kinds of cells use, 85 with cell-cell communication and 27 with transcription factors and other gene regulatory proteins. All of the 1213 clusters were subjected to whole-mount in situ hybridization to analyze the gene expression profiles at this stage. A total of 387 clusters showed expression specific to a certain tissue or organ; 149 showed epidermis-specific expression; 34 were specific to the nervous system; 29 to endoderm; 112 to mesenchyme; 32 to notochord; and 31 to muscle. Many genes were also specifically expressed in multiple tissues. The study also highlighted characteristic gene expression profiles dependent on the tissues. In addition, several genes showed intriguing expression patterns that have not been reported previously; for example, four genes were expressed specifically in the nerve cord cells and one gene was expressed only in the posterior part of muscle cells. This study provides molecular markers for each of the tissues and/or organs that constitutes the Ciona tailbud embryo. The sequence information will also be used for further genome scientific approach to explore molecular mechanisms involved in the formation of one of the most primitive chordate body plans.

Animals↗
PubMed2001

Early embryonic expression of a LIM-homeobox gene Cs-lhx3 is downstream of beta-catenin and responsible for the endoderm differentiation in Ciona savignyi embryos.

In early Ciona embryos, nuclear accumulation of beta-catenin is most probably the first step of endodermal cell specification. If beta-catenin is mis- and/or overexpressed, presumptive notochord cells and epidermal cells change their fates into endodermal cells, whereas if beta-catenin nuclear localization is downregulated by the overexpression of cadherin, the endoderm differentiation is suppressed, accompanied with the differentiation of extra epidermal cells ( Imai, K., Takada, N., Satoh, N. and Satou, Y. (2000) Development 127, 3009-3020). Subtractive hybridization screens of mRNAs between beta-catenin overexpressed embryos and cadherin overexpressed embryos were conducted to identify potential beta-catenin target genes that are responsible for endoderm differentiation in Ciona savignyi embryos. We found that a LIM-homeobox gene (Cs-lhx3), an otx homolog (Cs-otx) and an NK-2 class gene (Cs-ttf1) were among beta-catenin downstream genes. In situ hybridization signals for early zygotic expression of Cs-lhx3 were evident only in the presumptive endodermal cells as early as the 32-cell stage, those of Cs-otx in the mesoendodermal cells at the 32-cell stage and those of Cs-ttf1 in the endodermal cells at the 64-cell stage. Later, Cs-lhx3 was expressed again in a set of neuronal cells in the tailbud embryo, while Cs-otx was expressed in the anterior nervous system of the embryo. Expression of all three genes was upregulated in beta-catenin overexpressed embryos and downregulated in cadherin overexpressed embryos. Injection of morpholino oligonucleotides against Cs-otx did not affect the embryonic endoderm differentiation, although the formation of the central nervous system was suppressed. Injection of Cs-ttf1 morpholino oligonucleotides also failed to suppress the endoderm differentiation, although injection of its synthetic mRNAs resulted in ectopic development of endoderm differentiation marker alkaline phosphatase. By contrast, injection of Cs-lhx3 morpholino oligo suppressed the endodermal cell differentiation and this suppression was rescued by injection of Cs-lhx3 mRNA into eggs. In addition, although injection of delE-Ci-cadherin mRNA into eggs resulted in the suppression of alkaline phosphatase development, injection of delE-Ci-cadherin mRNA with Cs-lhx3 mRNA rescued the alkaline phosphatase development. These results strongly suggest that a LIM-homeobox gene Cs-lhx3 is one of the beta-catenin downstream genes and that its early expression in embryonic endodermal cells is responsible for their differentiation.

Amino Acid Sequence↗
PubMed2000

Muscle actin genes and muscle cells in the appendicularian, Oikopleura longicauda: phylogenetic relationships among muscle tissues in the urochordates.

Appendicularians (larvaceans) are planktonic tunicates. They possess a tail throughout their life, which marks a distinct difference between appendicularians and the other tunicate groups, including salps, doliolids, pyrosomes, and ascidians. We isolated cDNA clones encoding muscle-type and cytoplasmic-type actin isoforms from the appendicularian, Oikopleura longicauda. The types of the actin isoforms were confirmed by amino acid identities in the diagnostic residues compared to those of the other chordate muscle and cytoplasmic actins. Interestingly the appendicularian muscle actin isoform sequence has an intermediate feature between the ascidian tail (larval) muscle actin isoform and the body-wall (adult) muscle actin isoform. Analysis of a genomic clone from a muscle actin gene revealed that it contains only one intron in the coding region. It is located at a position that does not correspond to those of any introns reported in other deuterostome actin genes. Whole-mount in situ hybridization shows that the muscle actin transcript is detected specifically in the tail muscle cells of late tailbud-stage embryos. A signal is also found transiently in the region where the heart will form. In adults, the gene is expressed in tail muscle cells but not in the heart. Together with results of cytochemical and histochemical studies demonstrating the structure of muscle tissue, the present study highlights characteristics of appendicularian muscle organization, which are compared with those of the larval and adult muscle of ascidians.

Actins↗