The Experts below are selected from a list of 150 Experts worldwide ranked by ideXlab platform
Kenji Kiguchi - One of the best experts on this subject based on the ideXlab platform.
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Morphogenesis in the Early Embryo of the Lepidopteran Bombyx mori
Developmental biology, 1994Co-Authors: Lisa M. Nagy, Lynn M. Riddiford, Kenji KiguchiAbstract:Abstract The regional patterns of nuclear and cell division and the changes in size and shape of the developing Bombyx mori embryo were monitored from just prior to Blastoderm formation until the onset of gastrulation. Nuclear invasion of the periphery and subsequent cellularization occurs with a marked anterior to posterior gradient. Consequently, there is no syncytial Blastoderm stage in which all nuclei simultaneously rest at the periphery. In addition, the posteriormost Blastoderm cells do not form pole cells. Prior to gastrulation, the Bombyx Blastoderm cells undergo several unusual types of cell behaviors, indicated in part by the modifications and specializations of their lateral edges. Subsequent to the completion of cellularization, localized regions of mitosis can be found within the germ anlage, but at the stage monitored, just prior to the onset of gastrulation, these regions do not appear to be the equivalent of the Drosophila mitotic domains. The implications of these findings for modeling how segmental fates are established in insects are discussed. This work confirms and extends the work of earlier histological investigations of Bombyx development.
Jae Yong Han - One of the best experts on this subject based on the ideXlab platform.
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The avian-specific small heat shock protein HSP25 is a constitutive protector against environmental stresses during Blastoderm dormancy.
Scientific reports, 2016Co-Authors: Young Sun Hwang, Young-min Kim, Young Hyun Park, Tamao Ono, Jae Yong HanAbstract:Small heat shock proteins (sHSPs) range in size from 12 to 42 kDa and contain an α-crystalline domain. They have been proposed to play roles in the first line of defence against various stresses in an ATP-independent manner. In birds, a newly oviposited Blastoderm can survive several weeks in a dormant state in low-temperature storage suggesting that Blastoderm cells are basically tolerant of environmental stress. However, sHSPs in the stress-tolerant Blastoderm have yet to be investigated. Thus, we characterised the expression and function of sHSPs in the chicken Blastoderm. We found that chicken HSP25 was expressed especially in the Blastoderm and was highly upregulated during low-temperature storage. Multiple alignments, phylogenetic trees, and expression in the Blastoderms of Japanese quail and zebra finch showed homologues of HSP25 were conserved in other avian species. After knockdown of chicken HSP25, the expression of pluripotency marker genes decreased significantly. Furthermore, loss of function studies demonstrated that chicken HSP25 is associated with anti-apoptotic, anti-oxidant, and pro-autophagic effects in chicken Blastoderm cells. Collectively, these results suggest avian HSP25 could play an important role in association with the first line of cellular defences against environmental stress and the protection of future embryonic cells in the avian Blastoderm.
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microrna mediated posttranscriptional regulation is required for maintaining undifferentiated properties of Blastoderm and primordial germ cells in chickens
Proceedings of the National Academy of Sciences of the United States of America, 2011Co-Authors: Sang In Lee, Young Sun Hwang, Boram Lee, Hyung Chul Lee, Deivendran Rengaraj, Gwonhwa Song, Tae Sub Park, Jae Yong HanAbstract:MicroRNAs (miRNAs) play a critical role in determining the differentiation fate of pluripotent stem cells and germ cells in mammals. However, the mechanism(s) of miRNA-mediated posttranscriptional regulation with regard to lineage specification and differentiation in chick development require further investigation. Therefore, we conducted miRNA expression profiling to explore specific miRNA signatures in undifferentiated Blastoderm and primordial germ cells (PGCs). We identified seven miRNAs that are highly expressed in Blastoderm and 10 that are highly expressed in PGCs. In this study, miR-302a and miR-456 for Blastoderm and miR-181a* for PGCs were analyzed further for their target transcripts and regulatory pathways. Both miR-302a and miR-456 bound directly to the sex-determining region Y box 11 transcript and could act as posttranscriptional coregulators to maintain the undifferentiated state of the chicken Blastoderm through the suppression of somatic gene expression and differentiation. Moreover, miR-181a* showed a bifunctional role in PGCs by binding to two different transcripts. miR-181a* inhibited the somatic differentiation of PGCs by silencing homeobox A1 expression. Additionally, miR-181a* prevented PGCs from entering meiosis through the repression of the nuclear receptor subfamily 6, group A, member 1 transcript. Collectively, our data demonstrate that in chickens miRNAs intrinsically regulate the differentiation fate of Blastoderms and PGCs and that the specific timing of germ cell meiosis is controlled through miRNA expression.
Ariel D. Chipman - One of the best experts on this subject based on the ideXlab platform.
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Mutual regulatory interactions of the trunk gap genes during Blastoderm patterning in the hemipteran Oncopeltus fasciatus.
Developmental biology, 2010Co-Authors: Jonathan Ben-david, Ariel D. ChipmanAbstract:Abstract The early embryo of the milkweed bug, Oncopeltus fasciatus, appears as a single cell layer – the embryonic Blastoderm – covering the entire egg. It is at this Blastoderm stage that morphological domains are first determined, long before the appearance of overt segmentation. Central to the process of patterning the Blastoderm into distinct domains are a group of transcription factors known as gap genes. In Drosophila melanogaster these genes form a network of interactions, and maintain sharp expression boundaries through strong mutual repression. Their restricted expression domains define specific areas along the entire body. We have studied the expression domains of the four trunk gap gene homologues in O. fasciatus and have determined their interactions through dsRNA gene knockdown experiments, followed by expression analyses. While the Blastoderm in O. fasciatus includes only the first six segments of the embryo, the expression domains of the gap genes within these segments are broadly similar to those in Drosophila where the Blastoderm includes all 15 segments. However, the interactions between the gap genes are surprisingly different from those in Drosophila, and mutual repression between the genes seems to play a much less significant role. This suggests that the well-studied interaction pattern in Drosophila is evolutionarily derived, and has evolved from a less strongly interacting network.
Yuji Nakajima - One of the best experts on this subject based on the ideXlab platform.
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nodal signal is required for morphogenetic movements of epiblast layer in the pre streak chick Blastoderm
Development Growth & Differentiation, 2011Co-Authors: Nariaki Yanagawa, Masahide Sakabe, Hirokazu Sakata, Toshiyuki Yamagishi, Yuji NakajimaAbstract:During axis formation in amniotes, posterior and lateral epiblast cells in the area pellucida undergo a counter-rotating movement along the midline to form primitive streak (Polonaise movements). Using chick Blastoderms, we investigated the signaling involved in this cellular movement in epithelial-epiblast. In cultured posterior Blastoderm explants from stage X to XI embryos, either Lefty1 or Cerberus-S inhibited initial migration of the explants on chamber slides. In vivo analysis showed that inhibition of Nodal signaling by Lefty1 affected the movement of DiI-marked epiblast cells prior to the formation of primitive streak. In Lefty1-treated embryos without a primitive streak, Brachyury expression showed a patchy distribution. However, SU5402 did not affect the movement of DiI-marked epiblast cells. Multi-cellular rosette, which is thought to be involved in epithelial morphogenesis, was found predominantly in the posterior half of the epiblast, and Lefty1 inhibited the formation of rosettes. Three-dimensional reconstruction showed two types of rosette, one with a protruding cell, the other with a ventral hollow. Our results suggest that Nodal signaling may have a pivotal role in the morphogenetic movements of epithelial epiblast including Polonaise movements and formation of multi-cellular rosette.
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Heart myofibrillogenesis occurs in isolated chick posterior Blastoderm: a culture model.
Acta histochemica et cytochemica, 2006Co-Authors: Hiroko Matsui, Masahide Sakabe, Hirokazu Sakata, Toshiyuki Yamagishi, Kazuki Nakatani, Kazuo Ikeda, Mitsuru Fukui, Katsumi Ando, Yuji NakajimaAbstract:Early cardiogenesis including myofibrillogenesis is a critical event during development. -Recently we showed that prospective cardiomyocytes reside in the posterior lateral Blastoderm in the chick embryo. Here we cultured the posterior region of the chick Blastoderm in serum-free medium and observed the process of myofibrillogenesis by immunohistochemistry. After 48 hours, explants expressed sarcomeric proteins (sarcomeric alpha-actinin, 61%; smooth muscle alpha-actin, 95%; Z-line titin, 56%; sarcomeric myosin, 48%); however, they did not yet show a mature striation. After 72 hours, more than 92% of explants expressed I-Z-I proteins, which were incorporated into the striation in 75% of explants or more (sarcomeric alpha-actinin, 75%; smooth muscle alpha-actin, 81%; Z-line titin, 83%). Sarcomeric myosin was -expressed in 63% of explants and incorporated into A-bands in 37%. The percentage incidence of expression or striation of I-Z-I proteins was significantly higher than that of sarcomeric myosin. Results suggested that the nascent I-Z-I components appeared to be generated independently of A-bands in the cultured posterior Blastoderm, and that the process of myofibrillogenesis observed in our culture model faithfully reflected that in vivo. Our Blastoderm culture model appeared to be useful to investigate the mechanisms regulating the early cardiogenesis.
Lisa M. Nagy - One of the best experts on this subject based on the ideXlab platform.
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Morphogenesis in the Early Embryo of the Lepidopteran Bombyx mori
Developmental biology, 1994Co-Authors: Lisa M. Nagy, Lynn M. Riddiford, Kenji KiguchiAbstract:Abstract The regional patterns of nuclear and cell division and the changes in size and shape of the developing Bombyx mori embryo were monitored from just prior to Blastoderm formation until the onset of gastrulation. Nuclear invasion of the periphery and subsequent cellularization occurs with a marked anterior to posterior gradient. Consequently, there is no syncytial Blastoderm stage in which all nuclei simultaneously rest at the periphery. In addition, the posteriormost Blastoderm cells do not form pole cells. Prior to gastrulation, the Bombyx Blastoderm cells undergo several unusual types of cell behaviors, indicated in part by the modifications and specializations of their lateral edges. Subsequent to the completion of cellularization, localized regions of mitosis can be found within the germ anlage, but at the stage monitored, just prior to the onset of gastrulation, these regions do not appear to be the equivalent of the Drosophila mitotic domains. The implications of these findings for modeling how segmental fates are established in insects are discussed. This work confirms and extends the work of earlier histological investigations of Bombyx development.