Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Background: Zebrafish have the ability for heart regeneration. However, another teleost animal model, the medaka, had not yet been investigated for this capacity. Results: Compared with zebrafish, the medaka heart responded differently to an injury: An excessive fibrotic response occurred in the medaka heart, and existing cardiomyocytes or cardiac progenitor cells remained dormant, resulting in no numerical difference between the uncut and injured heart with respect to the number of EdU-incorporated cardiomyocytes. The results obtained from the analysis of the medaka raldh2-GFP transgenic line showed a lack of raldh2 expression in the endocardium. Regarding periostin expression, the localization of medaka periostin-b, a marker of fibrillogenesis, in the medaka heart remained at the wound site at 30 dpa; whereas zebrafish periostin-b was no longer localized at the wound but was detected in the epicardium at that time. Conclusions: Compared with zebrafish heart regeneration, the medaka heart phenotypes suggest the possibility that the medaka could hardly regenerate its heart tissue or that these phenotypes for heart regeneration showed a delay. (C) 2014 Wiley Periodicals, Inc.

DOI： 10.1002/DVDY.24154

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Background: Ectodysplasin (Eda) signaling is essential for the morphogenesis of several ectodermal appendages. Results: Here, we report a medaka mutant, all-fin less (afl), which has a nonsense mutation in its eda gene. The adult afl fish displayed various abnormalities of its dermal skeleton, such as short and twisted fin rays, missing and abnormally shaped scales and teeth, and skull deformation. Focusing on the developing fin rays in the caudal region of afl larvae, we found that the fin rays did not elongate; although the initial formation of fin rays proceeded normally. Additionally, eda expression was lost, and the expression pattern of edar, the gene for the receptor of Eda, was different from wild-type one. In vivo imaging of the double-transgenic medaka expressing enhanced green fluorescent protein under control of the edar promoter and DsRed under control of the osterix promoter revealed that edar expression preceded that of osterix and that the edar-expressing cells migrated in the direction of fin ray elongation, indicating that the Eda/Edar signaling event precedes osteoblast differentiation. Conclusions: Our findings provide evidence that Eda signaling accompanied with the binding of Eda to Edar are essential for fin ray formation guided by cell migration. Developmental Dynamics 243:765-777, 2014. (c) 2014 Wiley Periodicals, Inc.

DOI： 10.1002/dvdy.24120

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Androgens play key roles in the morphological specification of male type sex attractive and reproductive organs, whereas little is known about the developmental mechanisms of such secondary sex characters. Medaka offers a clue about sexual differentiation. They show a prominent masculine sexual character for appendage development, the formation of papillary processes in the anal fin, which has been induced in females by exogenous androgen exposure. This current study shows that the development of papillary processes is promoted by androgen-dependent augmentation of bone morphogenic protein 7 (Bmp7) and lymphoid enhancer-binding factor-1 (Lef1). Androgen receptor (AR) subtypes, AR alpha and AR beta, are expressed in the distal region of outgrowing bone nodules of developing papillary processes. Development of papillary processes concomitant with the induction of Bmp7 and Lef1 in the distal bone nodules by exposure to methyltestosterone was significantly suppressed by an antiandrogen, flutamide, in female medaka. When Bmp signaling was inhibited in methyltestosterone-exposed females by its inhibitor, dorsomorphin, Lef1 expression was suppressed accompanied by reduced proliferation in the distal bone nodules and retarded bone deposition. These observations indicate that androgen-dependent expressions of Bmp7 and Lef1 are required for the bone nodule outgrowth leading to the formation of these secondary sex characteristics in medaka. The formation of androgen-induced papillary processes may provide insights into the mechanisms regulating the specification of sexual features in vertebrates.

DOI： 10.1210/en.2013-1507

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Genome editing using engineered nucleases such as transcription activator-like effector nucleases (TALENs) has become a powerful technology for reverse genetics. In this study, we have described efficient detection methods for TALEN-induced mutations at endogenous loci and presented guidelines of TALEN design for efficient targeted mutagenesis in medaka, Oryzias latipes. We performed a heteroduplex mobility assay (HMA) using an automated microchip electrophoresis system, which is a simple and high-throughput method for evaluation of in vivo activity of TALENs and for genotyping mutant fish of F1 or later generations. We found that a specific pattern of mutations is dominant for TALENs harboring several base pairs of homologous sequences in target sequence. Furthermore, we found that a 5 T, upstream of each TALEN-binding sequence, is not essential for genomic DNA cleavage. Our findings provide information that expands the potential of TALENs and other engineered nucleases as tools for targeted genome editing in a wide range of organisms, including medaka.

DOI： 10.1111/dgd.12104

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The vertebrate mineralized skeleton is known to have first emerged as an exoskeleton that extensively covered the fossil jawless fish. The evolutionary origin of this exoskeleton has long been attributed to the emergence of the neural crest, but experimental evaluation for this is still poor. Here we determine the embryonic origin of scales and fin rays of medaka (teleost trunk exoskeletons) by applying long-term cell labelling methods, and demonstrate that both tissues are mesodermal in origin. Neural crest cells, however, fail to contribute to these tissues. This result suggests that the trunk neural crest has no skeletogenic capability in fish, instead highlighting the dominant role of the mesoderm in the evolution of the trunk skeleton. This further implies that the role of the neural crest in skeletogenesis has been predominant in the cephalic region from the early stage of vertebrate evolution.

DOI： 10.1038/ncomms2643

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Vertebrate hematopoiesis is characterized by two evolutionally conserved phases of development, i.e., primitive hematopoiesis, which is a transient phenomenon in the early embryo, and definitive hematopoiesis, which takes place in the later stages. Beni fuji (bef) was originally isolated as a medaka mutant that has an apparently reduced number of erythrocytes in its peripheral blood. Positional cloning revealed that the bef mutant has a nonsense mutation in the c-myb gene. Previous studies have shown that c-myb is essential for definitive hematopoiesis, and c-myb is now widely used as a marker gene for the onset of definitive hematopoiesis. To analyze the phenotypes of the bef mutant, we performed whole-mount in situ hybridization with gene markers of hematopoietic cells. The bef embryos showed decreased expression of alpha-globin and I-plastin, and a complete loss of mpo1 and rag1 expression, suggesting that the bef embryos had defects not only in erythrocytes but also in other myeloid cells, which indicates that their definitive hematopoiesis was aberrant. Interestingly, we observed a diminution in the number of primitive erythrocytes and a delay in the emergence of primitive macrophages in the bef embryos. These results suggest that c-myb also functions in the primitive hematopoiesis, potentially demonstrating a link between primitive and definitive hematopoiesis. (C) 2010 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.ydbio.2010.06.031

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We characterized a medaka mutant, vertebra imperfecta (vbi), that displays skeletal defects such as craniofacial malformation and delay of vertebra formation. Positional cloning analysis revealed a nonsense mutation in sec24d encoding a component of the COPII coat that plays a role in anterograde protein trafficking from the endoplasmic reticulum (ER) to the Golgi apparatus. Immunofluorescence analysis revealed the accumulation of type II collagen in the cytoplasm of craniofacial chondrocytes, notochord cells, and the cells on the myoseptal boundary in vbi mutants. Electron microscopy analysis revealed dilation of the ER and defective secretion of ECM components from cells in both the craniofacial cartilage and notochord in vbi. The higher vertebrates have at least 4 sec24 paralogs; however, the function of each paralog in development remains unknown. sec24d is highly expressed in the tissues that are rich in extracellular matrix and is essential for the secretion of ECM component molecules leading to the formation of craniofacial cartilage and vertebra. (C) 2010 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.ydbio.2010.03.016

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The floor plate is a key organizer that controls the specification of neurons in the central nervous system. Here, we show a new role of the floor plate: segmental pattern formation of the vertebral column. Analysis of a spontaneous medaka mutant, fused centrum (fsc), which exhibits fused centra and the absence of the intervertebral ligaments, revealed that fsc encodes wnt4b, which was expressed exclusively in the floor plate. In fsc mutants, we found that wnt4b expression was completely lost in the floor plate and that abnormal conversion of the intervertebral ligament cells into osteoblasts appeared to cause a defect of the intervertebral ligaments. The establishment of the transgenic rescue lines and mosaic analyses allowed the conclusion to be drawn that production of wnt4b by floor plate cells is essential for the segmental patterning of the vertebral column. Our findings provide a novel perspective on the mechanism of vertebrate development.

DOI： 10.1242/dev.051540

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Ectodermal contribution to the induction of pharyngeal teeth that form in the endodermal territory of the oropharyngeal cavity in some teleost fishes has been a matter of considerable debate. To determine the role of ectodermal cell signaling in scale and tooth formation and thereby to gain insights in evolutionary origin of teeth, we analyzed scales and teeth in rs-3 medaka mutants characterized by reduced scale numbers due to aberrant splicing of the ectodysplasin-A receptor (edar). Current data show that, in addition to a loss of scales (83% reduction), a drastic loss of teeth occurred in both oral (43.5% reduction) and pharyngeal (73.5% reduction) dentitions in rs-3. The remaining scales of rs-3 were irregular in shape and nearly 3 times larger in size relative to those of the wild-type. In contrast, there was no abnormality in size and shape in the remaining teeth of rs-3. In wild-type medaka embryos, there was a direct contact between the surface ectoderm and rostral endoderm in pharyngeal regions before the onset of pharyngeal tooth formation. However, there was no sign of ectodermal cell migration in the pharyngeal endoderm and hence no direct evidence of any ectodermal contribution to pharyngeal odontogenesis. These data suggest differential roles for Eda-Edar signaling in the induction and growth of scales and teeth and support the intrinsic odontogenic competence of the rostral endoderm in medaka.

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There are two hatching enzyme homologues in the zebrafish genome: zebrafish hatching enzyme ZHE1 and ZHE2. Northern blot and RT-PCR analysis revealed that ZHE1 was mainly expressed in pre-hatching embryos, whereas ZHE2 was rarely expressed. This was consistent with the results obtained in an experiment conducted at the protein level, which demonstrated that one kind of hatching enzyme, ZHE1, was able to be purified from the hatching liquid. Therefore, the hatching of zebrafish embryo is performed by a single enzyme, different from the finding that the medaka hatching enzyme is an enzyme system composed of two enzymes, medaka high choriolytic enzyme (MHCE) and medaka low choriolytic enzyme (MLCE), which cooperatively digest the egg envelope. The six ZHE1-cleaving sites were located in the N-terminal regions of egg envelope subunit proteins, ZP2 and ZP3, but not in the internal regions, such as the ZP domains. The digestion manner of ZHE1 appears to be highly analogous to that of MHCE, which partially digests the egg envelope and swells the envelope. The cross-species digestion using enzymes and substrates of zebrafish and medaka revealed that both ZHE1 and MHCE cleaved the same sites of the egg envelope proteins of two species, suggesting that the substrate specificity of ZHE1 is quite similar to that of MHCE. However, MLCE did not show such similarity. Because HCE and LCE are the result of gene duplication in the evolutionary pathway of Teleostei, the present study suggests that ZHE1 and MHCE maintain the character of an ancestral hatching enzyme, and that MLCE acquires a new function, such as promoting the complete digestion of the egg envelope swollen by MHCE.

DOI： 10.1111/j.1742-4658.2008.06722.x

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Developing neural tubes are bilaterally symmetric in all vertebrate embryos, irrespective of the presence of gene networks that generate left-right asymmetry. To explore the mechanisms that underlie the bilaterally symmetric formation of the neural tube, we examined a medaka (Oryzias latipes) dominant mutant, Oot, the neural tube of which transiently lacks normal symmetry in the optic tectum. We found that spatial changes in isthmic fgf8 expression do not occur on one side of the mutant, resulting in a transient desynchronized expression that correlates with tectal asymmetry. The application of exogenous FGF8 on one side of a wild-type embryo mimics the Oot phenotype, indicating that the bilaterally equivalent expression of isthmic fgf8 is crucial for the bilaterally symmetric development of the tectum. These results suggest that tectal symmetry is not a "default" state, but rather is maintained actively by a bilaterally coupled and synchronized regulation of isthmic fgf8 expression. genesis 46:537-545, 2008. (C) 2008 Wiley-Liss, Inc.

DOI： 10.1002/dvg.20424

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We examined the expression and functions of Pax1 and Pax9 in a teleost fish, the medaka Oryzias latipes. While Pax1 and Pax9 show distinct expression in the sclerotome in amniotes, we could not detect the differential expression of Pax1 and Pax9 in the developing sclerotome of the medaka. Furthermore, unlike the mouse, in which Pax1 is essential for development of the vertebral body, and where the neural arch is formed independent of either Pax1 or Pax9, our morpholino knockdown experiments revealed that both Pax1 and Pax9 are indispensable for the development of the vertebral body and neural arch. Therefore, we conclude that after gene duplication, Pax1 and Pax9 subfunctionalize their roles in the sclerotome independently in teleosts and amniotes. In Stage-30 embryo, Pax9 was strongly expressed in the posterior mesoderm, as was also observed for mouse Pax9. Since this expression was not detected for Pax1 in the mouse or fish, this new expression in the posterior mesoderm likely evolved in Pax9 of ancestral vertebrates after gene duplication. Two-month-old fish injected with Pax9 morpholino oligonucleotide showed abnormal morphology in the tail hypural skeletal element, which may have been related to this expression.

DOI： 10.1002/dvg.20381

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

Forkhead box (Fox) genes are involved in organogenesis and cell differentiation. A mutation of FOXP2 was discovered in patients with severe defects in speech and language. The medaka FoxP2 was cloned in order to clarify the molecular evolution and difference in the protein structure and function by comparing human/mouse and medaka genes. The result showed that medaka FoxP2 had a 73.7% homology to the human and mouse counterparts, and its zinc finger, leucine zipper and forkhead domain structures were conserved. However, medaka FoxP2 lacked a long polyglutamine repeat and had two insertions of unique amino acid sequences. FoxP2 expression was found in the epiphysis and retina, in addition to the midbrain and cerebellum. The transcriptional assay revealed that medaka FoxP2 showed a very weak repressive activity to the CC10 promoter while mouse Foxp2 exhibited a strong repressive activity. Mutational analyses of medaka FoxP2 showed that the three amino acids of forkhead domain were responsible for the weak repressive activity. These results suggest that medaka FoxP2 may play a different function in the development of the medaka fish.

DOI： 10.1093/jb/mvm235

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Little is known about the genes and processes involved in the development of otoliths. In this study, we isolated the biomineralization-related genes otolin and chondromodulin-1 (chm1) from medaka, and examined their spatiotemporal expression pattern as well as that of two other genes also related to biomineralization, i.e., sparclosteonectin and type II collagen (col2a), during otic development in medaka. Our results demonstrated that all the tested genes were expressed in the otic vesicle, and that chm1 was exclusively expressed in the semicircular canal of the otic vesicle. (c) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.modgep.2007.10.001

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The vertebral column is a defined feature of vertebrates. In birds and mammals, the sclerotome yields cartilaginous material for the vertebral column. In teleosts, however, it remains uncertain whether the sclerotome participates in vertebral column formation. To investigate osteoblast development in the teleost, we established transgenic systems that allow in vivo observation of osteoblasts and their progenitors marked by fluorescence of DsRed and enhanced green fluorescent protein (EGFP), respectively. In twist-EGFP transgenic medaka, EGFP-positive cells first appeared in the ventromedial portion of respective somites corresponding to the sclerotome, migrated dorsally around the notochord, and concentrated in the intervertebral regions. Ultrastructural analysis of the intervertebral regions revealed that some of these cells were directly located on the osteoidal surface of the perichordal centrum., and enriched with rough endoplasmic reticulum in their cytoplasm. By using the double transgenic medaka of twist-EGFP and osteocalcin-DsRed, we clarified that the EGFP-positive cells in the intervertebral region differentiated into mature osteoblasts expressing the DsRed. In vivo bone labeling in fact confirmed active matrix formation and mineralization of the perichordal centrum exclusively in the intervertebral region of zebrafish larvae as well as medaka larvae. These findings strongly suggest that the teleost intervertebral region acts as a growth center of the perichordal centrum, where the sclerotome-derived cells differentiate into osteoblasts.

DOI： 10.1002/dvdy.21329

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Hoxb8 has been suggestively implicated in the formation of the zone of polarizing activity (ZPA) in the limb bud. However, as hoxb8(-/-) mice did not show any defects in their limb development, the role of Hoxb8 during limb development has not been fully elucidated. Here, we report the identification of the medaka hoxb8a mutant, unextended-fin (ufi), in which all the fin tissues were malformed. Since the abnormal phenotype was observed in the caudal fin, the ufi phenotype suggests that the medaka Hoxb8a has a fundamental role in the formation of appendages protruding from the trunk. Our analyses revealed that the expression of wnt5a, a regulator of cell migration that signals through the non-canonical Wnt/Ca2+ pathway, was down-regulated in the ufi fin-folds. In fact, we found that the proximal-distal cell migration was impaired in ufi mutants and that the defect could be reversed by the injection of a Wnt5a protein. Moreover, we show herein that the numbers of proliferating cells and osteoblastic cells were increased in the ufi mutants. According to these results, we propose that the medaka Hoxb8a protein functions in the outgrowth of appendages through the regulation of cell migration and osteoblast differentiation. (c) 2006 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.ydbio.2006.02.017

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We examined the morphogenesis and regionalization of the embryonic brain of an acanthopterygian teleost, medaka (Oryzias latipes), by in situ hybridization using 14 gene probes. We compared our results with previous studies in other vertebrates, particularly zebrafish, an ostariophysan teleost. During the early development of the medaka neural rod, three initial brain vesicles arose: the anterior brain vesicle, which later developed into the telencephalon and rostral diencephalon; the intermediate brain vesicle, which later developed into the caudal diencephalon, mesencephalon, and metencephalon; and the posterior brain vesicle, which later developed into the myelencephalon. In the late neural rod, the rostral brain bent ventrally and the axis of the brain had a marked curvature at the diencephalon. In the final stage of the neural rod, ventricles began to develop, transforming the neural rod into the neural tube. In situ hybridization revealed that the brain can be divided into three longitudinal zones (dorsal, intermediate, and ventral) and many transverse subdivisions, on the basis of molecular expression patterns. The telencephalon was subdivided into two transverse domains. Our results support the basic concept of neuromeric models, including the prosomeric model, which suggests the existence of a conserved organization of all vertebrate neural tubes. Our results also show that brain development in medaka differs from that reported in other vertebrates, including zebrafish, in gene-expression patterns in the telencephalon, in brain vesicle formation, and in developmental speed. Developmental and genetic programs for brain development may be somewhat different even among teleosts. (C) 2004 Wiley-Liss, Inc.

DOI： 10.1002/cne.20219

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Medaka is an attractive model to study epimorphic regeneration. The fins have remarkable regenerative capacity and are replaced about 14 days after amputation. The formation of blastema, a mass of undifferentiated cells, is essential for regeneration; however, the molecular mechanisms are incompletely defined. To identify the genes required for fin regeneration, especially for blastema formation, we constructed cDNA libraries from fin regenerates at 3 days postamputation and 10 days postamputation. A total of 16,866 expression sequence tags (ESTs) were sequenced and subjected to BLASTX analysis. The result revealed that about 60% of them showed strong matches to previously identified proteins, and major signaling molecules related to development, including FGF, BMP, Wnt, Notch/Delta, and Ephrin/Eph signaling pathways were isolated. To identify novel genes that showed specific expression during fin regeneration, cDNA microarray was generated based on 2900 independent ESTs from each library which had no sequence similarity to known proteins. We obtained 6 candidate genes associated with blastema formation by gene expression pattern screening in competitive hybridization analyses and in situ hybridization. Olrfe16d23 and olrfe14k04 were expressed only in early regenerating stages when blastema formation was induced. The expression of olrf5n23, which encodes a novel signal peptide, was detected in wound epidermis throughout regeneration. Olrfe23122, olrfe20n22 and olrfe24i02 were expressed notably in the blastema region. Our study has thus identified the gene expression profiles and some novel candidate genes to facilitate elucidation of the molecular mechanisms of fin regeneration. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

DOI： 10.1016/j.mod.2004.03.015

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Medaka twist, a basic helix-loop-helix (bHLH) transcription factor, is expressed in the sclerotome during embryogenesis. We previously established a line of twist-EGFP transgenic medaka, whose EGFP expression is regulated by the twist promoter; therefore, we could observe the behavior of sclerotomal cells in vivo. In the transgenic medaka embryos, EGFP-positive sclerotomal cells migrated dorsally around the notochord and the neural tube, where at a later stage the vertebral column would be formed. This finding strongly suggests that twist-expressing sclerotomal cells participate in vertebral column formation in medaka. To clarify the function of twist gene in the sclerotome, we performed knockdown analysis of twist by using two kinds of morpholino antisense oligonucleotides targeted against twist (MO1 and MO2). Both the MO1 and MO2 morphants exhibited absence of neural arches, which are bilaterally paired, dorsomedially oriented bones on the dorsal aspect of the centrum. In addition, MO2, which blocks translation of only endogenous twist mRNA in the twist-EGFP transgenic medaka. did not affect the migration pattern of EGFP-positive cells, revealing that the migration of sclerotome-derived cells were normal in the absence of twist gene function. These results demonstrate that medaka twist functions in vertebral column formation by regulating the sclerotomal cell differentiation. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

DOI： 10.1016/j.mod.2004.03.008

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A genetic screen for mutations affecting embryogenesis in the medaka, Oryzias latipes, identified a mutant, whiteout (who), that exhibited hypochromic anemia. The who mutant initially had the normal number of blood cells, but it then gradually decreased during the embryonic and larval stages. The blood cells in the who mutants show an elongated morphology and little hemoglobin activity. Genetic mapping localized who to the vicinity of a LG12 marker, olgc1. By utilizing the highly conserved synteny between medaka and pufferfish, we identified a gene for 8-aminolevulinic acid dehydratase (ALAD), which is the second enzyme in the heme synthetic pathway, as a candidate for who. We found a missense mutation in the alad gene that was tightly linked to the who phenotype, strongly suggesting that the hypochromic anemia phenotype in the who mutant is caused by a loss of the alad function. Thus, who mutants represent a model for the human disease ALAD-deficiency porphyria. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

DOI： 10.1016/j.mod.2004.03.030

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The vascular system is highly conserved in all vertebrates in the aspects of anatomy as well as in the genetic mechanism governing it. The embryo of the medaka. Oryzias latipes is small and transparent, providing many advantages for the experimental analysis of the vertebrate vascular system. We isolated a novel medaka transglutaminase gene, termed embryonic transglutaminase, and found that it showed the highest homology to the coagulation factor XIII A subunit of mammals. This gene is expressed in the anterior lateral plate mesoderm, and then expressed specifically in yolk veins consisting two ducts of Cuvier and the vitellocaudal vein. Our data is the first finding that a coagulation factor XIII-like gene is expressed in the early vascular development of vertebrates. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.modgep.2003.11.004

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The myoseptum of fishes, composed of dense collagen, is a connective tissue layer that forms in the embryo, dividing somites from the trunk, and its structure and function are similar to those of the mammalian tendon. Both the myoseptum and tendon serve as the transmitter of muscular contractility to bones and adjoining muscles, and their structure is indispensable for movement of vertebrate animals. We cloned the zebrafish periostin gene and examined its expression and function in the myoseptum. The expression in embryos started in the rostral part of each segmented somite in the early segmentation stage; and consequently, metameric stripes were observed. At the end of segmentation, the expression region shifted to the transverse myoseptum and the myotome-epidermis boundary, and each myotome was surrounded by periostin. Using a polyclonal antibody, we found that the periostin protein was localized to the transverse myoseptum. Consistently, periostin morpholino antisense oligonucleotide led to defects in myoseptum formation, a delay in the differentiation of myofibers, and disorder of connection between myofibrils and myoseptum. We demonstrated here that periostin is the first molecule involved in myoseptum formation and propose that periostin secretion on the surface of the myoseptum is required for the adhesion of muscle fiber bundles to the myoseptum and the differentiation of muscle fibers. (C) 2004 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.ydbio.2003.12.007

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DOI： 10.1016/S1567-133X(02)00021-2

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The zebrafish zisp gene encodes a putative transmembrane protein with a DHHC zinc finger motif. At the segmentation period zisp is expressed in the adaxial cells and the somites in a striping pattern. The zisp transcripts are localized to the posterior parts within the individual somites. In fused somites mutants, zisp is expressed throughout the somitic mesoderm. These expression patterns are similar to those of myoD. In addition to the somitic expression, the zisp expression was observed in lens cells at the late segmentation period and the early pharyngula period. © 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S1567-133X(02)00021-2

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The zebrafish zisp gene encodes a putative transmembrane protein with a DHHC zinc finger motif. At the segmentation period zisp is expressed in the adaxial cells and the somites in a striping pattern. The zisp transcripts are localized to the posterior parts within the individual somites. In fused somites mutants, zisp is expressed throughout the somitic mesoderm. These expression patterns are similar to those of myoD. In addition to the somitic expression, the zisp expression was observed in lens cells at the late segmentation period and the early pharyngula period. (c) 2003 Elsevier Science Ireland Ltd. All rights reserved.

DOI： 10.1016/s0925-4773(03)00133-3

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Drosophila Polycomb group proteins are thought to form multimeric nuclear complexes that are responsible for stable transmission of repressed states of gene expression during the proliferation of differentiating embryos. In this study, we cloned, sequenced, and characterized two Polycomb group homologs, designated pcl and psel, in zebrafish. Amino acid sequence analyses determined that pcl is a structural homolog of Drosophila Polycomb and that pscl is a homolog of Drosophila Posterior sex combs. Northern blots and whole-mount in situ hybridization revealed that pcl and pscl had overlapping expression patterns at successive stages of embryogenesis. Immunocytochemistry localized both Pcl and Pscl protein in blastomere nuclei. Pull-down assays and two-hybrid system deletion analyses showed that these proteins were capable of homotypic and heterotypic interactions and identified the regions required for these interactions. The evidence supports the idea that zebrafish Polycomb group proteins, like those of other species, form nuclear complexes with compositions that may vary in a spatio-temporal manner during development. (C) 2002 Elsevier Science (USA). All rights reserved.

DOI： 10.1016/S0006-291X(02)00497-7

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Cbfa1, a transcription factor of the runt family, was recently shown to be a key regulator in skeletal development in mammals. Ln the present study, we identified the cbfa1 gene from the medaka, Oryzias latipes. The amino acid sequence, including the runt domain, is highly conserved with that of mammalian cbfa1. Whole mount in situ hybridization showed that the medaka cbfa1 was expressed prominently in immature osteoblasts and chondrocytes of the developing skeletal structures during embryogenesis. The expression pattern suggests functional and evolutionary implications of the cbfa1 gene in chondrocyte differentiation between teleosts and mammals.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER VERLAG  

The hatching enzyme of the teleost, Oryzias latipes, is composed of two proteases, high choriolytic enzyme (choriolysin H, HCE) and low choriolytic enzyme (choriolysin L, LCE), which are similar in some enzymological characteristics and protein structure (55% identity in amino acid sequence) and belong to the astacin family. Two isoforms of HCE are detected. In the present study, the genes for HCE and LCE were isolated from the genomic library constructed from DNA of the inbred drR strain fish. In contrast to the close similarity of the enzymes, there was a marked difference in their gene organization. The LCE gene was a single copy gene and composed of eight exons interrupted by seven introns. The HCE genes were multicopy genes and lacked introns. In the haploid genome of the drR strain fish, there are eight HCE genes, seven of which were cloned. Each HCE gene was identified as that for either of the two isoforms of HCE. 5' flanking regions of the LCE gene and the HCE genes had consensus TATA box sequences, but not CAT box nor GC box sequences. The big difference in the exon-intron organization between the HCE genes and the LCE gene is discussed from an evolutionary viewpoint.

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