DOI： 10.1242/dev.202079

PubMed

掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌  

OBJECTIVE: Cambodia is located within the distribution range of the red junglefowl, the common ancestor of domestic chickens. Although a variety of indigenous chickens have been reared in Cambodia since ancient times, their genetic characteristics have yet to be sufficiently defined. Here, we conducted a large-scale population genetic study to investigate the genetic diversity and population genetic structure of Cambodian indigenous chickens and their phylogenetic relationships with other chicken breeds and native chickens worldwide. METHODS: A Bayesian phylogenetic tree was constructed based on 625 mitochondrial DNA D-loop sequences, and Bayesian clustering analysis was performed for 666 individuals with 23 microsatellite markers, using samples collected from 28 indigenous chicken populations in 24 provinces and three commercial chicken breeds. RESULTS: A total of 92 haplotypes of mitochondrial D-loop sequences belonging to haplogroups A to F and J were detected in Cambodian chickens; in the indigenous chickens, haplogroup D (44.4%) was the most common, and haplogroups A (21.0%) and B (13.2%) were also dominant. However, haplogroup J, which is rare in domestic chickens but abundant in Thai red junglefowl, was found at a high frequency (14.5%), whereas the frequency of haplogroup E was considerably lower (4.6%). Population genetic structure analysis based on microsatellite markers revealed the presence of three major genetic clusters in Cambodian indigenous chickens. Their genetic diversity was relatively high, which was similar to findings reported for indigenous chickens from other Southeast Asian countries. CONCLUSION: Cambodian indigenous chickens are characterized by mitochondrial D-loop haplotypes that are common to indigenous chickens throughout Southeast Asia, and may retain many of the haplotypes that originated from wild ancestral populations. These chickens exhibit high population genetic diversity, and the geographical distribution of three major clusters may be attributed to inter-regional trade and poultry transportation routes within Cambodia or international movement between Cambodia and other countries.

DOI： 10.5713/ab.21.0351

PubMed

掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌  

The precursor of heme, protoporphyrin IX (PPIX), accumulates abundantly in the uteri of birds, such as Japanese quail, Coturnix japonica, which has brown-speckled eggshells; however, the molecular basis of PPIX production in the uterus remains largely unknown. Here, we investigated the cause of low PPIX production in a classical Japanese quail mutant exhibiting white eggshells by comparing its gene expression in the uterus with that of the wild type using transcriptome analysis. We also performed genetic linkage analysis to identify the causative genomic region of the white eggshell phenotype. We found that 11 genes, including 5'-aminolevulinate synthase 1 (ALAS1) and hephaestin-like 1 (HEPHL1), were specifically upregulated in the wild-type uterus and downregulated in the mutant. We mapped the 172 kb candidate genomic region on chromosome 6, which contains several genes, including a part of the paired-like homeodomain 3 (PITX3), which encodes a transcription factor. ALAS1, HEPHL1, and PITX3 were expressed in the apical cells of the luminal epithelium and lamina propria cells of the uterine mucosa of the wild-type quail, while their expression levels were downregulated in the cells of the mutant quail. Biochemical analysis using uterine homogenates indicated that the restricted availability of 5'-aminolevulinic acid is the main cause of low PPIX production. These results suggest that uterus-specific transcriptional regulation of heme-biosynthesis-related genes is an evolutionarily acquired mechanism of eggshell pigment production in Japanese quail. Based on these findings, we discussed the molecular basis of PPIX production in the uteri of Japanese quails.

DOI： 10.1371/journal.pone.0265008

PubMed

担当区分：筆頭著者,　最終著者   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/dvdy.323

その他URL： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/dvdy.323

担当区分：責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌  

DOI： 10.15252/embj.2020105375

PubMed

その他URL： https://onlinelibrary.wiley.com/doi/full-xml/10.15252/embj.2020105375

担当区分：責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌  

DOI： 10.1038/s41598-021-81589-7

PubMed

その他URL： http://www.nature.com/articles/s41598-021-81589-7

掲載種別：研究論文（学術雑誌）  

Background: The phalanges are the final skeletal elements to form in the vertebrate limb and their identity is regulated by signaling at the phalanx forming region (PFR) located at the tip of the developing digit ray. Here, we seek to explore the relationship between PFR activity and phalanx morphogenesis, which define the most distal limb skeletal elements, and signals associated with termination of limb outgrowth. Results: As Grem1 is extinguished in the distal chick limb mesoderm, the chondrogenesis marker Aggrecan is up-regulated in the metatarsals and phalanges. Fate mapping confirms that subridge mesoderm cells contribute to the metatarsal and phalanges when subridge Grem1 is down-regulated. Grem1 overexpression specifically blocks chick phalanx development by inhibiting PFR activity. PFR activity and digit development are also disrupted following overexpression of a Gli3 repressor, which results in Grem1 expression in the distal limb and downregulation of Bmpr1b. Conclusions: Based on expression and fate mapping studies, we propose that downregulation of Grem1 in the distal limb marks the transition from metatarsal to phalanx development. This suggests that downregulation of Grem1 in the distal limb mesoderm is necessary for phalanx development. Grem1 downregulation allows for full PFR activity and phalanx progenitor cell commitment to digit fate.

DOI： 10.1002/dvdy.431

担当区分：責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌  

DOI： 10.1002/dvdy.222

PubMed

その他URL： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/dvdy.222

担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌  

DOI： 10.1038/s42003-020-0870-z

PubMed

その他URL： http://www.nature.com/articles/s42003-020-0870-z

担当区分：最終著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌  

DOI： 10.3390/ani10112074

PubMed

担当区分：責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌  

DOI： 10.1371/journal.pone.0240183

PubMed

担当区分：責任著者   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/dvg.23388

その他URL： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/dvg.23388

担当区分：最終著者   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/dgd.12682

その他URL： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/dgd.12682

担当区分：責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌  

DOI： 10.1096/fj.201901757r

PubMed

その他URL： https://onlinelibrary.wiley.com/doi/full-xml/10.1096/fj.201901757R

レンチウイルス感染により作成したEGFP遺伝子導入ニワトリ株における、遺伝子の統合部位と発達中の器官の蛍光強度を解析した。導入遺伝子はMED27のエクソン3と4の間に局在した。一部のホモ接合体とヘテロ接合体は胚の早期段階で致死的であった。パラフィン切片の抗GFP抗体による免疫組織化学法により、St.14、17、24の導入遺伝子胚のEGFP発現の組織学的分析を行った。次に凍結切片を作成し、それぞれの組織における導入遺伝子から直接EGFP蛍光強度を測定した。その結果、胚の発達段階や組織において、EGFP発現は特徴がみられた。野生型細胞と一緒に微量培養したEGFP発現細胞は、生細胞画像を介してはっきりと識別することができた。

ニワトリ胚へのin ovoエレクトロポレーション(EP)で注入部位に関する指標の代替色素として、Brilliant Blueが適していることを見出した。Brilliant Blueは0.2%でDNA注入部位の追跡に十分であった。この化学物質ではEP後に赤色蛍光が観察されなかった。これらの結果から、Brilliant BlueはEPによってニワトリ胚に導入された赤色蛍光蛋白質を検出するために利用可能と考えられた。また、レポーター遺伝子EGFPとmCherryを一緒にEPした後、2種の蛍光強度を正確に測定するためBrilliant Blueを使用したところ、蛍光強度の平均を算出するために有用なツールであると考えられた。

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

Abstract

Chick embryo electroporation is a powerful tool for the introduction of transgenes into tissues of interest for the study of developmental biology. This method often uses Fast Green to visualize the injected area by staining the solution containing DNA green. Here, we show that Fast Green fluoresces in a red color after electroporation, suggesting that researchers need to be cautious when detecting red fluorescence. Fast Green solution did not show any fluorescence before injection into chick embryos, but fluoresced red within 3 min post‐injection into chick embryos. We identified Brilliant Blue as suitable alternative dye for use as an indicator of injection sites in ovo electroporation. We found that 0.2% of Brilliant Blue was sufficient to track the area of DNA injection. In addition, this chemical did not show red fluorescence after electroporation. Our findings demonstrate that Brilliant Blue can be used for detecting red fluorescent proteins introduced into chick embryos by electroporation. Our study also shows useful examples for the application of Brilliant Blue for the precise quantification of two fluorescence intensities after EGFP and mCherry co‐electroporation.

DOI： 10.1111/dgd.12629

その他URL： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/dgd.12629

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

Elucidating how body parts from different primordia are integrated during development is essential for understanding the nature of morphological evolution. In tetrapod evolution, while the position of the hindlimb has diversified along with the vertebral formula, the mechanism responsible for this coordination has not been well understood. However, this synchronization suggests the presence of an evolutionarily conserved developmental mechanism that coordinates the positioning of the hindlimb skeleton derived from the lateral plate mesoderm with that of the sacral vertebrae derived from the somites. Here we show that GDF11 secreted from the posterior axial mesoderm is a key factor in the integration of sacral vertebrae and hindlimb positioning by inducing Hox gene expression in two different primordia. Manipulating the onset of GDF11 activity altered the position of the hindlimb in chicken embryos, indicating that the onset of Gdf11 expression is responsible for the coordinated positioning of the sacral vertebrae and hindlimbs. Through comparative analysis with other vertebrate embryos, we also show that each tetrapod species has a unique onset timing of Gdf11 expression, which is tightly correlated with the anteroposterior levels of the hindlimb bud. We conclude that the evolutionary diversity of hindlimb positioning resulted from heterochronic shifts in Gdf11 expression, which led to coordinated shifts in the sacral-hindlimb unit along the anteroposterior axis.

DOI： 10.1038/s41559-017-0247-y

PubMed

掲載種別：研究論文（学術雑誌）  

To understand organ morphogenetic mechanisms, it is essential to clarify how spatiotemporally-regulated molecular/cellular dynamics causes physical tissue deformation. In the case of vertebrate limb development, while some of the genes and oriented cell behaviors underlying morphogenesis have been revealed, tissue deformation dynamics remains incompletely understood. We here introduce our recent work on the reconstruction of tissue deformation dynamics in chick limb development from cell lineage tracing data. This analysis has revealed globally-aligned anisotropic tissue deformation along the proximo-distal axis not only in the distal region but also in the whole limb bud. This result points to a need, as a future challenge, to find oriented molecular/cellular behaviors for realizing the observed anisotropic tissue deformation in both proximal and distal regions, which will lead to systems understanding of limb morphogenesis.

DOI： 10.1016/j.gde.2017.04.005

PubMed

DOI： 10.1016/j.mod.2017.04.060

掲載種別：研究論文（学術雑誌）  

Background: The organizing center, which serves as a morphogen source, has crucial functions in morphogenesis in animal development. The center is necessarily located in a certain restricted area in the morphogenetic field, and there are several ways in which an organizing center can be restricted. The organizing center for limb morphogenesis, the ZPA (zone of polarizing activity), specifically expresses the Shh gene and is restricted to the posterior region of the developing limb bud.Results: The pre-pattern along the limb anteroposterior axis, provided by anterior Gli3 expression and posterior Hand2 expression, seems insufficient for the initiation of Shh expression restricted to a narrow, small spot in the posterior limb field. Comparison of the spatiotemporal patterns of gene expression between Shh and some candidate genes (Fgf8, Hoxd10, Hoxd11, Tbx2, and Alx4) upstream of Shh expression suggested that a combination of these genes' expression provides the restricted initiation of Shh expression.Conclusions: Taken together with results of functional assays, we propose a model in which positive and negative transcriptional regulatory networks accumulate their functions in the intersection area of their expression regions to provide a restricted spot for the ZPA, the source of morphogen, Shh. Developmental Dynamics 246:417-430, 2017. (c) 2017 Wiley Periodicals, Inc.

DOI： 10.1002/dvdy.24493

PubMed

掲載種別：論文集(書籍)内論文  

Electroporation enables delivering bionanomolecules, such as DNAs, RNAs, siRNAs, and morpholinos, into chick embryos in a spatially and temporally restricted fashion. Recent advances in electroporation techniques allowed us to deliver transgenes into the restricted area of the limb bud and to analyze the function of the enhancers in the limb field. Here, we describe the introduction of transgenes by electroporation in the limb field and its application on enhancer analysis.

DOI： 10.1007/978-1-4939-7216-6_13

PubMed

Reptile development is an intriguing research target for understating the unique morphogenesis of reptiles as well as the evolution of vertebrates. However, there are numerous difficulties associated with studying development in reptiles. The number of available reptile eggs is usually quite limited. In addition, the reptile embryo is tightly adhered to the eggshell, making it a challenge to isolate reptile embryos intact. Furthermore, there have been few reports describing efficient procedures for isolating intact embryos especially prior to pharyngula stage. Thus, the aim of this review is to present efficient procedures for obtaining early-stage reptilian embryos intact. We first describe the method for isolating early-stage embryos of the Japanese striped snake. This is the first detailed method for obtaining embryos prior to oviposition in oviparous snake species. Second, we describe an efficient strategy for isolating early-stage embryos of the soft-shelled turtle.

DOI： 10.1111/dgd.12278

PubMed

国際・国内誌：国際誌  

Hereditary Multiple Malformation (HMM) is a naturally occurring, autosomal recessive, homozygous lethal mutation found in Japanese quail. Homozygote embryos (hmm-/-) show polydactyly similar to talpid2 and talpid3 mutants. Here we characterize the molecular profile of the hmm-/- limb bud and identify the cellular mechanisms that cause its polydactyly. The hmm-/- limb bud shows a severe lack of sonic hedgehog (SHH) signaling, and the autopod has 4 to 11 unidentifiable digits with syn-, poly-, and brachydactyly. The Zone of Polarizing Activity (ZPA) of the hmm-/- limb bud does not show polarizing activity regardless of the presence of SHH protein, indicating that either the secretion pathway of SHH is defective or the SHH protein is dysfunctional. Furthermore, mesenchymal cells in the hmm-/- limb bud do not respond to ZPA transplanted from the normal limb bud, suggesting that signal transduction downstream of SHH is also defective. Since primary cilia are present in the hmm-/- limb bud, the causal gene must be different from talpid2 and talpid3. In the hmm-/- limb bud, a high amount of GLI3A protein is expressed and GLI3 protein is localized to the nucleus. Our results suggest that the regulatory mechanism of GLI3 is disorganized in the hmm-/- limb bud.

DOI： 10.3389/fcell.2016.00149

PubMed

掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.ydbio.2015.08.006

PubMed

掲載種別：研究論文（学術雑誌）  

Tissue-level characterization of deformation dynamics is crucial for understanding organ morphogenetic mechanisms, especially the interhierarchical links among molecular activities, cellular behaviors and tissue/organ morphogenetic processes. Limb development is a well-studied topic in vertebrate organogenesis. Nevertheless, there is still little understanding of tissue-level deformation relative to molecular and cellular dynamics. This is mainly because live recording of detailed cell behaviors in whole tissues is technically difficult. To overcome this limitation, by applying a recently developed Bayesian approach, we here constructed tissue deformation maps for chick limb development with high precision, based on snapshot lineage tracing using dye injection. The precision of the constructed maps was validated with a clear statistical criterion. From the geometrical analysis of the map, we identified three characteristic tissue growth modes in the limb and showed that they are consistent with local growth factor activity and cell cycle length. In particular, we report that SHH signaling activity changes dynamically with developmental stage and strongly correlates with the dynamic shift in the tissue growth mode. We also found anisotropic tissue deformation along the proximal-distal axis. Morphogenetic simulation and experimental studies suggested that this directional tissue elongation, and not local growth, has the greatest impact on limb shaping. This result was supported by the novel finding that anisotropic tissue elongation along the proximal-distal axis occurs independently of cell proliferation. Our study marks a pivotal point for multi-scale system understanding in vertebrate development.

DOI： 10.1242/dev.109728

PubMed

掲載種別：研究論文（学術雑誌）  

The morphogenesis of snake embryos is an elusive yet fascinating research target for developmental biologists. However, few data exist on development of early snake embryo due to limited availability of pregnant snakes, and the need to harvest early stage embryos directly from pregnant snakes before oviposition without knowing the date of fertilization. We established an ex vivo culture method for early snake embryos using the Japanese striped snake, Elaphe quadrivirgata. This method, which we named sausage-style (SS) culture, allows us to harvest snake embryos at specific stages for each experiment. Using this SS culture system, we calculated somite formation rate at early stages before oviposition. The average somite formation rate between 6/7 and 12/13 somite stages was 145.9min, between 60/70 and 80/91 somite stages 42.4min, and between 113-115 and 126/127 somite stages 71min. Thus, somite formation rate that we observed during early snake embryogenesis was changed over time. We also describe a developmental staging series for E.quadrivirgata. This is the first report of a developmental series of early snake embryogenesis prior to oviposition by full-color images with high-resolution. We propose that the SS culture system is an easy method for treating early snake embryos ex vivo.

DOI： 10.1111/dgd.12157

PubMed

掲載種別：研究論文（学術雑誌）  

To understand the morphogenetic mechanisms of organ development and regeneration, it is essential to clarify the inter-hierarchical relationship between microscopic, molecular/cellular activities and organ-level tissue deformation dynamics. While the former have been studied for several decades, the latter macroscopic geometrical information about physical tissue deformation - is often missing, especially for many vertebrates. This is mainly because live recording of detailed cell behaviors in whole tissues during vertebrate organogenesis is technically difficult. In this study, we have developed a novel method that combines snapshot lineage tracing with Bayesian statistical estimation to construct whole-organ deformation maps from landmark data on limited numbers of space-time points. Following the validation of the method using artificially generated data sets, we applied it to the analysis of tissue deformation dynamics in chick limb development. A quantitative tissue deformation map for St.23-St.24 has been constructed, and its precision has been proven by evaluating its predictive performance. Geometrical analyses of the map have revealed a spatially heterogeneous volume growth pattern that is consistent with the expression pattern of a major morphogen and anisotropic tissue deformation along an axis. Thus, our method enables deformation dynamics analysis in organogenesis using practical lineage marking techniques. (C) 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

DOI： 10.1016/j.jtbi.2014.04.027

掲載種別：研究論文（学術雑誌）  

Background: The forelimb-specific gene tbx5 is highly conserved and essential for the development of forelimbs in zebrafish, mice, and humans. Amongst birds, a single order, Dinornithiformes, comprising the extinct wingless moa of New Zealand, are unique in having no skeletal evidence of forelimb-like structures.
Results: To determine the sequence of tbx5 in moa, we used a range of PCR-based techniques on ancient DNA to retrieve all nine tbx5 exons and splice sites from the giant moa, Dinornis. Moa Tbx5 is identical to chicken Tbx5 in being able to activate the downstream promotors of fgf10 and ANF. In addition we show that missexpression of moa tbx5 in the hindlimb of chicken embryos results in the formation of forelimb features, suggesting that Tbx5 was fully functional in wingless moa. An alternatively spliced exon 1 for tbx5 that is expressed specifically in the forelimb region was shown to be almost identical between moa and ostrich, suggesting that, as well as being fully functional, tbx5 is likely to have been expressed normally in moa since divergence from their flighted ancestors, approximately 60 mya.
Conclusions: The results suggests that, as in mice, moa tbx5 is necessary for the induction of forelimbs, but is not sufficient for their outgrowth. Moa Tbx5 may have played an important role in the development of moa's remnant forelimb girdle, and may be required for the formation of this structure. Our results further show that genetic changes affecting genes other than tbx5 must be responsible for the complete loss of forelimbs in moa.

DOI： 10.1186/1471-2148-14-75

PubMed

Digit identity has been studied using the chick embryo as a model system for more than 40 years. Using this model system, several milestone findings have been reported, such as the apical ectodermal ridge (AER), the zone of polarizing activity (ZPA), the Shh gene, and the theory of morphogen and positional information. These experimental results and models provided context for understanding pattern formation in developmental biology. The focus of this review is on the determination of digit identity during limb development. First, the history of studies on digit identity determination is described, followed by descriptions of the molecular mechanisms and current models for determination of digit identity. Finally, future questions and remarkable points will be discussed.

DOI： 10.1111/dgd.12022

PubMed

掲載種別：研究論文（学術雑誌）  

The evolutionarily conserved, non-coding similar to 800-base-pair (bp) zone of polarizing activity (ZPA) regulatory sequence (ZRS) controls Shh expression in the posterior limb. We report that the chicken mutant oligozeugodactyly (ozd), which lacks limb Shh expression, has a large deletion within the ZRS. Furthermore, the preaxial polydactylous, Silkie Breed chicken, which develops ectopic anterior limb Shh expression, has a single bp change within the ZRS. Using an in vivo reporter assay to examine enhancer function in the chick limb, we demonstrate that the wild-type ZRS drives beta-galactosidase reporter expression in the ZPA of both wild-type and ozd limbs. The Silkie ZRS drives beta-galactosidase in both posterior and anterior Shh domains in wild-type limb buds. These results support the hypothesis that the ZRS integrates positive and negative prepatterned regulatory inputs in the chicken model system and demonstrate the utility of the chicken limb as an efficient genetic system for gene regulatory studies. Developmental Dynamics 240: 1212-1222, 2011. (C) 2011 Wiley-Liss, Inc.

DOI： 10.1002/dvdy.22634

PubMed

掲載種別：研究論文（学術雑誌）  

Half a century ago, thalidomide was widely prescribed to pregnant women as a sedative but was found to be teratogenic, causing multiple birth defects. Today, thalidomide is still used in the treatment of leprosy and multiple myeloma, although how it causes limb malformation and other developmental defects is unknown. Here, we identified cereblon (CRBN) as a thalidomide-binding protein. CRBN forms an E3 ubiquitin ligase complex with damaged DNA binding protein 1 (DDB1) and Cul4A that is important for limb outgrowth and expression of the fibroblast growth factor Fgf8 in zebrafish and chicks. Thalidomide initiates its teratogenic effects by binding to CRBN and inhibiting the associated ubiquitin ligase activity. This study reveals a basis for thalidomide teratogenicity and may contribute to the development of new thalidomide derivatives without teratogenic activity.

DOI： 10.1126/science.1177319

PubMed

掲載種別：論文集(書籍)内論文  

Limb development has been studied for over 100 years by several generations of developmental biologists. The developing limb is one of the best models with which to study pattern formation in vertebrates. We have used chick limb development to answer a simple but basic question, namely, why heterogeneous tissues are formed at correct positions and times from a homogeneous population of cells (Pearse &amp
Tabin, 1998). Limb development starts as two pairs of tissue bulges in the lateral plate meso-derm (LPM). These are called the forelimb and hindlimb fields (Fig. 9.1). After limb initiation, one can clearly identify three-dimensional axes in the limb buds: the proximal-distal (PD
from shoulder to fingers), dorso-ventral (DV
from back to palm), and antero-posterior (AP
from thumb to little fingers) axes. Morphological changes and differences along these three axes are determined by pattern formation during limb bud stages. Following establishment of these axes, one can visually recognize condensation of cartilages. Muscles, tendons, and neurons migrate and differentiate after cartilage formation. Because the stages and events are easily recognized morphologically and in detail, it is therefore the limb bud is an excellent model with which to study the molecular mechanisms of embryonic patterning and tissue differentiation in vertebrates. © 2009 Springer Japan.

DOI： 10.1007/978-4-431-09427-2_9

Electroporation is a powerful tool with which to study limb development. Limb development, however, remains an intricate series of events, requiring the precise dissection of developmental processes using relevant transgenes. In this review, we describe the anatomy of the limb field as the basis of targeted electroporation, and specific expression vectors are discussed. We share a useful protocol for electroporation of chick limb buds, and the expression pattern of enhanced green fluorescent protein in the limb buds is used to demonstrate relevant embryonic patterning. Finally, useful trouble-shooting techniques are described.

DOI： 10.1111/j.1440-169x.2008.01054.x

PubMed

掲載種別：研究論文（学術雑誌）  

The zone of polarizing activity is the primary signaling center controlling anterior-posterior patterning of the amniote limb bud. The autopodial interdigits (IDs) are secondary signaling centers proposed to determine digit identity by acting on the cells of the digital ray. Here, we focus on events accompanying digital fate determination and define a region of the digital ray that expresses Sox9 and Bmpr1b and is phosphorylated-SMAD1/5/8 (p-SMAD1/5/8) positive. We name this region the phalanx-forming region (PFR), and show that the PFR cells arise from the distal subridge mesenchyme of digital ray. This phalanx-forming cell lineage is subsequently committed to the cartilage lineage; the fate of these cells is initially labile but becomes fixed as they are incorporated into the condensed cartilage of the digit primordium. Using an in vivo reporter assay, we establish that each digital PFR has a unique p-SMAD1/5/8 activity signature. In addition, we show that changes in this activity correlate with the identity of the digit that forms after experimental manipulation, supporting the idea that threshold signaling levels can lead to different developmental outcomes in a morphogenetic field. Our data define the molecular profile of the PFR, and we propose a model for understanding formation and variation of digits during autopodial development.

DOI： 10.1073/pnas.0707899105

PubMed

掲載種別：研究論文（学術雑誌）  

Based on recent data, a new view is emerging that vertebrate Dachshund (Dach) proteins are components of Six1/6 transcription factor-dependent signaling cascades. Although Drosophila data strongly suggest a tight link between Dpp signaling and the Dachshund gene, a functional relationship between vertebrate Dach and BMP signaling remains undemonstrated. We report that chick Dach1 interacts with the Smad complex and the corepressor mouse Sin3a, thereby acting as a repressor of BMP-mediated transcriptional control. In the limb, this antagonistic action regulates the formation of the apical ectodermal ridge (AER) in both the mesenchyme and the AER itself, and also controls pattern formation along the proximodistal axis of the limb. Our data introduce a new paradigm of BMP antagonism during limb development mediated by Dach1, which is now proven to function in different signaling cascades with distinct interacting partners.

DOI： 10.1242/dev.01252

PubMed

掲載種別：研究論文（学術雑誌）  

Despite extensive studies on the anterior-posterior (AP) axis formation of limb buds, mechanisms that specify digit identities along the AP axis remain obscure. Using the four-digit chick leg as a model, we report here that Tbx2 and Tbx3 specify the digit identities of digits IV and III, respectively. Misexpression of Tbx2 and Tbx3 induced posterior homeotic transformation of digit III to digit IV and digit II to digit III, respectively. Conversely, misexpression of their mutants VP16DeltaTbx2 and VP16DeltaTbx3 induced anterior transformation. In both cases, alterations in the expression of several markers (e.g., BMP2, Shh, and HoxD genes) were observed. In addition, Tbx2 and Tbx3 rescued Noggin-mediated inhibition of interdigital BMP signaling, signaling which is pivotal in establishing digit identities. Hence, we conclude that Tbx3 specifies digit III, and the combination of Tbx2 and Tbx3 specifies digit IV, acting together with the interdigital BMP signaling cascade.

PubMed

掲載種別：研究論文（学術雑誌）  

A tight loop between members of the fibroblast growth factor and the Wnt families plays a key role in the initiation of vertebrate limb development. We show for the first time that Tbx5 and Tbx4 are directly involved in this process. When dominant-negative forms of these Tbx genes were misexpressed in the chick prospective limb fields, a limbless phenotype arose with repression of both Wnt and Fgf genes By contrast, when Tbx5 and Tbx4 were misexpressed in the flank, an additional wing-like and an additional leg-like limbs were induced, respectively. This additional limb formation was accompanied by the induction of both Wnt and Fgf genes These results highlight the pivotal roles of Tbx5 and Tbx4 during limb initiation, specification of forelimb/hindlimb and evolution of tetrapod limbs, placing Tbx genes at the center of a highly conserved genetic program.

DOI： 10.1242/dev.00474

PubMed

掲載種別：研究発表ペーパー・要旨（国際会議）  

DOI： 10.1016/j.ydbio.2008.05.516

会議種別：口頭発表（一般）  

会議種別：口頭発表（招待・特別）  

会議種別：口頭発表（招待・特別）  

会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

会議種別：口頭発表（招待・特別）  

会議種別：口頭発表（一般）  

会議種別：口頭発表（招待・特別）  

会議種別：口頭発表（招待・特別）  

会議種別：口頭発表（招待・特別）  

会議種別：口頭発表（招待・特別）  

会議種別：口頭発表（招待・特別）  

会議種別：口頭発表（招待・特別）  

会議種別：口頭発表（招待・特別）  

会議種別：口頭発表（招待・特別）  

会議種別：口頭発表（招待・特別）  

会議種別：口頭発表（招待・特別）