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排序方式: 共有161条查询结果,搜索用时 15 毫秒
81.
Vincent SD Norris DP Le Good JA Constam DB Robertson EJ 《Mechanisms of development》2004,121(11):1403-1415
In all vertebrates, invariant left/right (L/R) positioning and organization of the internal viscera is controlled by a conserved pathway. Nodal, a member of the TGFbeta superfamily is a critical upstream component responsible for initiating L/R axis determination. Asymmetric Nodal expression in the node preceeds and foreshadows morphological L/R asymmetry. Here we address the mechanism of Nodal activation in the left LPM by studying the function of a novel enhancer element, the AIE. We show this element is exclusively active in cells of the left lateral plate mesoderm (LPM) and is not itself responding to Nodal asymmetry. To test the hypothesis that this element may initiate asymmetric Nodal expression in the LPM, we deleted it from the mouse germ line. Mice homozygous for the AIE deletion (Nodal(deltaaie/deltaaie)) show no defects. However, we find that the AIE contributes to regulating the level of asymmetric Nodal activity; analysis of transheterozygous embryos (Nodal(deltaaie/null)) shows reduced Nodal expression in the left LPM associated with a low penetrance of L/R defects. Our findings point to the existence of two independent pathways that control Nodal expression in the left LPM. 相似文献
82.
Conformational features and binding affinities to Cripto,ALK7 and ALK4 of Nodal synthetic fragments 下载免费PDF全文
Luisa Calvanese Annamaria Sandomenico Andrea Caporale Annalia Focà Giuseppina Focà Gabriella D'Auria Lucia Falcigno Menotti Ruvo 《Journal of peptide science》2015,21(4):283-293
Nodal, a member of the TGF‐β superfamily, is a potent embryonic morphogen also implicated in tumor progression. As for other TGF‐βs, it triggers the signaling functions through the interaction with the extracellular domains of type I and type II serine/threonine kinase receptors and with the co‐receptor Cripto. Recently, we reported the molecular models of Nodal in complex with its type I receptors (ALK4 and ALK7) as well as with Cripto, as obtained by homology modeling and docking simulations. From such models, potential binding epitopes have been identified. To validate such hypotheses, a series of mutated Nodal fragments have been synthesized. These peptide analogs encompass residues 44–67 of the Nodal protein, corresponding to the pre‐helix loop and the H3 helix, and reproduce the wild‐type sequence or bear some modifications to evaluate the hot‐spot role of modified residues in the receptor binding. Here, we show the structural characterization in solution by CD and NMR of the Nodal peptides and the measurement of binding affinity toward Cripto by surface plasmon resonance. Data collected by both conformational analyses and binding measurements suggest a role for Y58 of Nodal in the recognition with Cripto and confirm that previously reported for E49 and E50. Surface plasmon resonance binding assays with recombinant proteins show that Nodal interacts in vitro also with ALK7 and ALK4 and preliminary data, generated using the Nodal synthetic fragments, suggest that Y58 of Nodal may also be involved in the recognition with these protein partners. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
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84.
Vijendra K. Sharma Robert Hänsch Ralf R. Mendel Jutta Schulze 《Plant Cell, Tissue and Organ Culture》2007,88(1):21-33
A successful regeneration system is presented for elite cultivars in barley and wheat based on nodes. Nodal explants were
excised from in vitro and ex vitro grown plants. A combination of 8.28 μM 4-amino-3,5,6-trichloropicolinic acid and 4.54 μM
to 22.71 μm thidiazuron (TDZ) used in MS-based medium containing 60 g l−1 maltose favoured induction of clumps of multiple shoots/buds with or without callus formation in the primary cultures. Within
8–10 weeks upon further subcultures, the proliferation into callus with rapid and continuously forming adventitious buds containing
clusters of meristemoids, termed meristematic bulk tissue (MBT) was obtained. Lowering the levels of growth regulators resulted
in redifferentiation of shoots, which elongated, rooted, developed into morphologically normal plants and set seeds normally.
With a frequency ranging between 37 and 82% the nodes raised from in vitro grown plants were proliferated into MBT independent
of TDZ concentration, cultivar and species. The average number of shoots per responding node in different cultivars was 7–15
in barley and 1–6 in wheat after 12–14 weeks. Nodes from greenhouse grown plants mainly responded for callus formation with
poor development of MBT. 相似文献
85.
Endoderm differentiation and movements are of fundamental importance not only for subsequent morphogenesis of the digestive tract but also to enable normal patterning and differentiation of mesoderm- and ectoderm-derived organs. This review defines the tissues that have been called endoderm in different species, their cellular origin and their movements. We take a comparative approach to ask how signaling pathways leading to embryonic and extraembryonic endoderm differentiation have emerged in different organisms, how they became integrated and point to specific gaps in our knowledge that would be worth filling. Lastly, we address whether the gastrulation movements that lead to endoderm internalization are coupled with its differentiation. 相似文献
86.
Nodal基因属于TGF-β超家族。它在小鼠原肠期的原条形成过程中起重要作用。Nodal基因的缺失导致中胚层不能形成。使小鼠死亡。用一系列含有Nodal基因5′侧翼序列其缺失体的荧光素酶报告基因质粒瞬时转化F9细胞。通过分析这些报告基因质粒的荧光素酶活性,在转录起始点上游的1kb处的EcoRⅠ附近找到一个抑制子元件。该抑制子元件的核心部分位于EcoRⅠ位点下游约200bp处,它几乎可以完全抑制No 相似文献
87.
88.
《Saudi Journal of Biological Sciences》2022,29(5):3425-3431
Present investigation was carried out to arrive at an effective micropropagation protocol for Winter Jasmine (Jasminum nudiflorum) using nodal segments from actively growing plants as explants. Explants were collected from current season shoots during April-May just after the initiation of new flush. Combined sterilization treatment of explants with 1.0% NaOCl2 for 10 min followed by 70% ethanol for 10 s recorded highest culture survival (63.88%) and optimum culture asepsis (63.88%) followed by the treatment containing 0.1% HgCl2 for 10 min followed by 70% ethanol for 10 s with culture survival (61.11%) and culture asepsis (69.44%). Highest culture establishment (80.55%) and minimum days to bud sprouting (7.62 days) was recorded with Benzyl adenine + Kinetin (3.0 + 1.0 mgL?1) but maximum length (4.33 cm) and leaf number (7.78) of established micro shoots was recorded with Benzyl adenine + Kinetin (1.0 + 0.5 mgL?1). Maximum proliferated shoots (2.41) and an optimum proliferation percentage (77.78 %) was recorded with Benzyl adenine + Kinetin (3.0 + 0.5 mgL?1). Minimum size of proliferated shoots (2.02 cm) was recorded with Benzyl adenine + Kinetin (3.0 + 1.0 mgL?1) followed by 2.25 cm recorded with Benzyl adenine + Kinetin (3.0 + 0.5 mgL?1). Highest rooting (63.93%), primary root number/microshoot (4.74) and longest primary roots (34.67 mm) were recorded with IBA (2.0 mgL?1). IBA yielded better results than NAA in terms of higher rooting percentage and root number. However, days to root initiation were found minimum (22.00) with 2.0 mgL?1 of NAA. Highest ex vitro survival of rooted microshoots (89.67%) was recorded with IBA (2.0 mgL?1). 相似文献
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90.
Andrzej Lebioda Roman Makarewicz Bogdan Ma?kowski Maciej Dancewicz Janusz Kowalewski Wieslawa Windorbska 《Reports of Practical Oncology and Radiotherapy》2013,18(2):76-81