N Satoh

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..Namely, the dorsalization of the aboral side of the ancestral embryo may have been a key developmental event that led to the formation of the basic chordate body plan...

..Interestingly, the combined pattern of spatial expression of As-T and As-T2 appears to correspond to that of a single vertebrate Brachyury gene...

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..This review is aimed to highlight the recent advances in ascidian embryology...

..These diagrams constitute a blueprint for the Ciona embryo and provide a foundation for understanding the evolutionary origins of the chordate body plan...

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..However, the expression of these genes as well as a mesenchyme-specific gene and histochemical activity of endoderm-specific alkaline phosphatase were evident by the mid-tailbud stage...

..The Pax1/9 genes therefore might provide the first developmental genetic corroboration of hypotheses of organ-level homology that unifies hemichordates, urochordates and cephalochordates...

..Namely, ApBra is expressed in an archenteron invagination region and a stomodaeum invagination region...

..These results suggest that, in addition to tissue-specific genes, the activities of a set of region-specific genes are associated with tail formation in the ascidian embryo...

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..Therefore, two different but partially overlapping mechanisms are required for the expression of Twist-like1 in the mesenchymal precursors, which triggers the differentiation of the mesenchyme in Ciona embryos...

..Evolutionary alteration in the genetic circuitry, especially downstream of this transcription factor, seems critical for the evolution of notochord and chordate body plan...

..Treatment of notochord precursor cells isolated from the 32-cell stage embryoswith bFGF resulted in upregulation of both the HNF-3 and Brachyury genes...

..These results suggest that the accumulation of (beta)-catenin in the nuclei of endoderm progenitor cells is the first step in the process of ascidian endoderm specification...

..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...

..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...

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..Cs-ZicL may provide a future experimental system to explore how the gene expression in multiple embryonic regions is controlled and how the single gene can perform different functions in multiple types of embryonic cells...

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..Taking into account the recent finding of maternal molecules for muscle differentiation, we propose a model for a genetic cascade that includes As-T2 as a regulator of muscle cell differentiation in the ascidian embryo...

..In addition, an enhancer-trap line was obtained. This is a demonstration of efficient, Minos-mediated transgenesis in marine invertebrates...

..Our results suggest that the autoregulative activity of these two ascidian T-box genes is also mediated by the DNA-binding domain, not by the transcription activation domain of the encoded proteins...

..All of the data fully characterized may be viewed at the web site http://ghost.zool.kyoto-u.ac.jp...

..These results suggest that the chordate ancestor had at least two muscle actin isoforms and that the vertebrate actin isoforms evolved after the separation of the vertebrates and urochordates...

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..These observations suggest implication of the two T-box genes, with different roles, in starfish gastrulation...

..Although we were not able to deduce their functions, this is the first report of maternal genes with mRNAs that are segregated with the endoplasm of ascidian embryos...

..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...

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..This is in agreement with the homology between their basic larval body plans with respect to coelomogenesis and allows us to discuss the evolutionary counterparts of the coelomopore complex in chordates...

..The present results therefore indicate that Twist-like 1 is required for the differentiation of most mesodermal precursors of adults...

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..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...

..The ascidian tadpole is regarded as a prototype of vertebrates, implying a similar function of pem in vertebrate embryogenesis...

..The expression patterns of some of these clones were changed during the larval period...

..In light of these results, we are continuing to investigate how and why notochord development is lost in tailless molgulid ascidian embryos...

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..This gene may be involved in the dynamic arrangement of cells during ascidian metamorphosis...

..These results provide the first evidence at the gene expression level for shared function between a part of the ascidian endostyle and the vertebrate follicular thyroid gland. J. Exp. Zool. ( Mol. Dev. Evol. ) 285:158-169, 1999...

..We discussed how the spatio-temporal expression pattern of HrEpiC1 is regulated by the two modules...

..These gene activities may be associated with changes in cell shape and adhesion during the intercalation and extension of the notochord cells...

..These results clearly demonstrate that an enhancer trap event that entrapped enhancers of Ci-Musashi occurred in C. intestinalis...

..The present comprehensive analysis therefore provides a means to study the role of these transcription factors in developmental processes of basal chordates...

..These results suggest that the ascidian M-Ras orthologue compensates for lacked classical Ras and plays essential roles in neurogenesis in the ascidian...

..It is likely that ascidian cellulose synthase is required for the coordination of the metamorphic events in the trunk and tail in addition to cellulose biosynthesis...

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..Taking recent gene expression studies and anatomical studies into consideration, we discuss ontogenetic and phylogenetic features of the amphioxus nervous system...

..However, the formation of pigment cells of the sensory organs was markedly disturbed. These results indicate that an appropriate level of syndecan expression is required for normal cell adhesion and morphogenesis of the ascidian embryo...

..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...

..Expression remains evident in the archenteron through gastrulation and then disappears. A new expression domain appears near the mouth along the preoral and postoral ciliated bands in the early tornaria larva...

..These results suggest that screening for developmental genes by the reverse genetic approach in Ciona intestinalis embryos is effective for identifying novel genes with developmental functions required for the development of chordates...

..In light of these observations, we suggest that the cluster organization and colinearity of the Hox genes are under dispersing and disintegrating conditions in C. intestinalis...

..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...

..The expression gradually disappeared during further development and was not detected in juveniles. These results indicate that the gene responsible for chordate brain formation is expressed in the ciliary bands of auricularia larvae...

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..Thus, the nervous system-specific genes in Ciona larvae will provide not only probes for determining their function but also clues for exploring the complex network of nervous system-specific genes...

..This kind of information is essential to form a comprehensive understanding of the overarching expression-control plan by which the basic chordate body is formed...

..The present results therefore provide molecular information for the investigation of complex developmental processes, and an insight into chordate evolution...

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..This may reflect different functional requirements of the locomotor larval muscle as opposed to the non-locomotor muscles of the sessile adult, and/or the biosynthetic demands of extremely rapid larval development...

..The large majority of the genes expressed in Ciona testis show no significant matches to known proteins and the further analysis of these genes may shed new light on the molecular mechanism of spermatogenesis and sperm functions...

..Therefore, Ciona intestinalis may provide an experimental system for exploring the basic genetic cascade associated with the signaling pathways in chordates...

..This HrBMPa expression profile resembled that of Xenopus BMP-7, implying a primordial function of BMP-7 among vertebrate BMPs-5-8...

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..This study demonstrates BP elevation in transgenic skinny mice and obese KKA(y) mice that are both hyperleptinemic, thereby suggesting the pathophysiological role of leptin in some forms of obesity-related hypertension...

..The present study provides evidence that leptin is an adipocyte-derived antidiabetic hormone in vivo and suggests its pathophysiologic and therapeutic implications in diabetes...

..Therefore, placodes are not likely to be a newly acquired feature in vertebrates, but may have already been possessed by the earliest chordates...

..These data provide the molecular basis for further functional studies of the endocrine role of the neural complex of ascidians...

..The inferred regulatory gene sets of the ancestral chordate would be an important foundation for understanding how tadpole-type larvae, a unique characteristic of chordates, evolved...

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..The present experimental results suggest that the expression and function of Cs-FGF4/6/9 and Cs-FoxD are not interdependent, and that the Notch pathway is involved in B-line notochord induction downstream of Cs-FoxD...

..These advances continue to increase the utility of Ciona intestinalis as a model organism whilst the integrated database will be useful for researchers in comparative and evolutionary genomics...

..The two T-box genes are primary mediators of macho1 function, and cooperation between the zygotically expressed transcription factors is indispensable for muscle cell differentiation in Ciona embryos...

..Therefore, we concluded that the posterior-most localization and mitochondria-like distribution appear to be major specialized patterns of maternal transcripts in early Ciona embryos...

..intestinalis will provide an experimental system to explore molecular mechanisms underlying color patterns, through future genome-wide studies...

..We propose a possible evolutionary scenario in which an ancestral Zic-related gene gave rise to both the macho-1-like muscle determinant gene as well as neuronal Zic genes...

..Thus, this study provides the first comprehensive evidence that the physical clustering of regulatory genes, or their target genes, is not relevant for the genome-wide control of gene expression during development...

..In addition, genes associated with the stress response and cell defense were upregulated, whereas genes involved in cell adhesion were downregulated...

..The type of large-scale screening used is, therefore, a powerful approach to identify novel genes with significant developmental functions, the details of which will be determined in future studies...

..The identification of these six FGF genes in the basal chordate gave us an insight into the diversification of specific subfamilies of vertebrate FGFs...

..Here we present evidence that this is the case, and that the EST count can therefore be used like "Northern blot analysis" of Ciona genes...

..In addition, the putative forebrain and midbrain expressed Ci-FgfL and Ci-Fgf9/16/20, respectively. Therefore, the regionalization of the ascidian larval central nervous system was also marked by the expression of Fgf genes...

..These results provide evidence that ZicL directly activates Brachyury, leading to specification and subsequent differentiation of notochord cells...

..In addition, the putative forebrain and midbrain expressed Ci-FgfL and Ci-Fgf9/16/20, respectively. Therefore, the regionalization of the ascidian larval central nervous system was also marked by the expression of Fgf genes...

..In vertebrates these ancestral cell junctions appear to have evolved into more diverse, and possibly more complex, forms, compared with those in their urochordate siblings...

..We also show that this method is efficient for coupling two so-far independent scaffolds into one longer scaffold when two BAC clones represent sequences located at either end of the two scaffolds...

..These descriptions and staging system provide a basis for studying cellular and molecular mechanisms underlying the development of adult organs and tissues of this basal chordate...

..The predicted amino acid sequence of Ci-Ends10 showed similarity to Trip230, and that of Ci-Ends11 resembled Ptp4E. These molecules might be useful for further analysis of the development, function and evolution of the endostyle...

..Furthermore, some of the genes including three Wnt genes noted in the quantitative analyses implied that Ci-macho1 is involved in the differentiation of endoderm and mesenchyme via intracellular communications...

..These results provide evidence that the differentiation of each of the three mesenchyme lineages of Ciona embryos is characterized by the expression of a specific set of genes, whose expression is controlled differentially...

..Since Ciona is regarded as one of the most primitive extant chordates, the present analysis gives us an insight into how these fundamental biological genes are evolved or are conserved during chordate evolution...