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1.
Expression of an epidermal antigen used to study tissue induction in the early Xenopus laevis embryo 总被引：4，自引：0，他引：4
A monoclonal antibody (Epi 1) has been produced that recognizes an antigen expressed in epidermal cells of Xenopus laevis embryos. The Epi 1 antigen appears in embryonic epidermis at the end of gastrulation and is not expressed in nonepidermal structures derived from ectoderm (for example, neural tube or cement gland). The capacity to express the Epi 1 antigen is restricted to cells of the animal hemisphere prior to the midblastula stage of development (stage 8), and tissue interactions during gastrulation inhibit the expression of the Epi 1 antigen in neural ectoderm. This epidermal antigen will be a valuable marker for studies of ectodermal commitment. 相似文献
2.
Anterior-specific neural induction can be assayed by means of an antibody that recognizes the Xenopus homeobox-containing protein En-2. The En-2 antigen is an excellent early marker, since it is present as a discrete band in the anterior neural plate of neurula embryos. Regional induction was assayed by combining dorsal mesoderm with competent ectoderm. Anterior notochord from the early neurula induced En-2 frequently, while posterior notochord induced En-2 less frequently. Presumptive somitic mesoderm and presumptive head mesoderm, though they induced neural tissue, were not strong inducers of En-2. Thus, anterior notochord may be the primary mesodermal tissue responsible for the patterning of the anterior neural plate. 相似文献
3.
The effect of the floor plate on pattern and polarity in the developing central nervous system 总被引：7，自引：0，他引：7
The effect of floor plate on cellular differentiation in the neural tube of quail embryos was examined. In the developing neural tube the floor plate, which consists of specialized neuroepithelial cells, is located in the ventral midline of the neural tube. When Hensen's node was extirpated the floor plate and notochord did not develop, and the normal differentiation of the ventral horn motor neurons and dorsal and ventral roots did not occur. When one side of the neural tube was deprived of notochord, the ventro-dorsal differentiation took place on both sides. However, when one side of the neural tube was deprived of the floor plate, the ventral horn motor neurons and dorsal and ventral roots did not develop on that side. These observations suggest that the floor plate influences motor neuron differentiation and acts as an intrinsic organizer to establish pattern and polarity in the developing nervous system. 相似文献
4.
[目的]从形态特征和生化遗传层面上丰富赤眼鳟种质资源研究数据,同时为筛选出鉴定赤眼鳟种群的生化遗传标记打下基础.[方法]采用形态学测量观察赤眼鳟的形态特征,并以聚丙烯酰胺凝胶电泳检测其不同组织(心脏、眼睛晶状体、肌肉、肝脏和肾脏)中的乳酸脱氢酶(LDH)和苹果酸脱氢酶(MDH),分析两种同工酶表达的组织特异性.[结果]赤眼鳟的眼上缘可见一红斑,鳃耙短而疏,主要形态特征为背鳍D.iii-7,胸鳍P.i-14,臀鳍A.iii-7~8,腹鳍V.i-8,其齿式2·4·5/4·4·2或2·4·4/4·4·2.从赤眼鳟的心脏、眼睛晶状体、肌肉、肝脏和肾脏等5种组织中共检测到7条LDH酶带和6条MDH酶带,不同组织中的酶带数目和活性各不相同,呈明显的组织特异性,且同一组织不同个体间也存在明显差异.[结论]同工酶表达的组织特异性除了受遗传基因调控外,还与各组织的生化代谢活动相关,其中心脏LDH可作为鉴定赤眼鳟种质的生化遗传标记. 相似文献
5.
口虾蛄乳酸脱氢酶同工酶组织特异性的研究 总被引：5，自引：0，他引：5
以口虾蛄为材料进行研究,用聚丙烯酰胶凝胶电泳法,对其肌肉、心胜、腹鳃、肝胰腺及眼球5种组织器官进行乳酸脱氢酶(LDH)同工酶的研究分析。结果表明：不同组织中乳酸脱氢酶(LDH)的同工酶谱带存在差异,具有明显的组织特异性。肌肉、腹鳃、肝胰腺和心脏中有2条酶带,眼球中只有1条酶带,心脏中的谱带表达最浓,而腹鳃中的酶带表达最弱。 相似文献
6.
Nerve growth factor attenuates neurotoxic effects of taxol on spinal cord-ganglion explants from fetal mice 总被引：3，自引：0，他引：3
Most neurons in organotypic cultures of dorsal root ganglia from 13-day-old fetal mice require high concentrations of nerve growth factor for survival during the first week after explanation. These nerve growth factor-enhanced sensory neurons mature and innervate the dorsal regions of attached spinal cord tissue even after the removal of exogenous growth factor after 4 days. In cultures exposed for 4 days to nerve growth factor and taxol (a plant alkaloid that promotes the assembly of microtubules) and returned to medium without growth factor, greater than 95 percent of the ganglionic neurons degenerated and the spinal cord tissues were reduced almost to monolayers. In contrast, when the recovery medium was supplemented with nerve growth factor, the ganglionic neurons and dorsal (but not ventral) cord tissue survived remarkably well. Dorsal cord neurons do not normally require an input from dorsal root ganglia for long-term maintenance in vitro, but during and after taxol exposure they become dependent for survival and recovery on the presence of neurite projections from nerve growth-factor-enhanced dorsal root ganglia. 相似文献
7.
Neuronal generation of the leech swimming movement 总被引：5，自引：0，他引：5
G S Stent W B Kristan W O Friesen C A Ort M Poon R L Calabrese 《Science (New York, N.Y.)》1978,200(4348):1348-1357
The swimming movement of the leech is produced by an ensemble of bilaterally symmetric, rhythmically active pairs of motor neurons present in each segmental ganglion of the ventral nerve cord. These motor neurons innervate the longitudinal muscles in dorsal or ventral sectors of the segmental body wall. Their duty cycles are phase-locked in a manner such that the dorsal and ventral body wall sectors of any given segment undergo an antiphasic contractile rhythm and that the contractile rhythms of different segments form a rostrocaudal phase progression. This activity rhythm is imposed on the motor neurons by a central swim oscillator, of which four bilaterally symmetric pairs of interneurons present in each segmental ganglion appear to constitute the major component. These interneurons are linked intra- and intersegmentally via inhibitory connections to form a segmentally iterated and inter-segmentally concatenated cyclic neuronal network. The network appears to owe its oscillatory activity pattern to the mechanism of recurrent cyclic inhibition. 相似文献
8.
稻谷腹部、背部微观结构差异性分析 总被引：3，自引：0，他引：3
【目的】从微观角度对糙米腹部、背部的结构差异性进行研究,从宏观角度对糙米的三点弯曲破碎力学性能进行研究,以建立微观结构与宏观力学性能之间的相关关系,为稻谷籽粒裂纹起始于腹部建立理论依据。【方法】对两个品种糙米横截面的腹部、背部在淀粉粒和细胞层次以及糊粉层进行扫描电镜观察,采用三点弯曲法测试糙米的破碎力学性能。【结果】糙米腹部、背部微观结构在淀粉粒、细胞层次以及糊粉层均存在差异,籽粒腹部、背部微观结构的差异对其腹部、背部的结构强度产生影响,使籽粒腹部的结构强度小于背部,与力学测试性能一致,并且腹部、背部微观断裂形式亦存在差异。【结论】稻谷籽粒在解吸和吸湿条件下裂纹起始于腹部与其腹部结构强度小于背部有关。 相似文献
9.
分离5~9周人胚胎生殖腺嵴和背侧肠系膜,采用组织块法进行体外培养,免疫细胞化学染色法检测SSEA-1、SSEA-3、Oct-4及hTERT在人胚胎生殖细胞中的表达,以证实利用组织块体外培养所获得的细胞为未分化的人胚胎生殖细胞。结果表明:组织块体外培养得到的细胞或细胞集落均阳性表达SSEA-1、SSEA-3、Oct-4及hTERT,说明组织块体外培养获得的细胞为未分化的人胚胎生殖细胞。 相似文献
10.
The trk proto-oncogene product: a signal transducing receptor for nerve growth factor. 总被引：108，自引：0，他引：108
D R Kaplan B L Hempstead D Martin-Zanca M V Chao L F Parada 《Science (New York, N.Y.)》1991,252(5005):554-558
The trk proto-oncogene encodes a 140-kilodalton, membrane-spanning protein tyrosine kinase (p140prototrk) that is expressed only in neural tissues. Nerve growth factor (NGF) stimulates phosphorylation of p140prototrk in neural cell lines and in embryonic dorsal root ganglia. Affinity cross-linking and equilibrium binding experiments with 125I-labeled NGF indicate that p140prototrk binds NGF specifically in cultured cells with a dissociation constant of 10(-9) molar. The identification of p140prototrk as an NGF receptor indicates that this protein participates in the primary signal transduction mechanism of NGF. 相似文献
11.
胚胎干细胞体外定向诱导分化研究进展 总被引：3，自引：1，他引：3
胚胎干细胞是由早期内细胞团分离的一种多潜能细胞 ,在体外分化抑制培养时 ,可保持未分化状态而无限增殖。一旦撤除分化抑制因素 ,或添加适当的诱导剂 ,ES细胞可分化为内胚层、中胚层和外胚层的多种类型的特化细胞。文章综述了体外定向诱导 ES细胞分化为造血细胞、心肌细胞、神经细胞、脂肪细胞、胰岛细胞、内皮细胞、上皮细胞、成骨细胞、软骨细胞和黑素细胞等的途径和方法。 相似文献
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[目的]掌握尖吻鲈仔鱼期的骨骼生长发育规律,为开展尖吻鲈骨骼发育相关基因研究及鱼类化石探究提供基础资料.[方法]采用软骨—硬骨双染染色技术,连续观测0~23日龄尖吻鲈仔鱼发育过程中脊柱及附肢骨骼中的胸鳍、背鳍、腹鳍、尾鳍、臀鳍形成及生长发育特征.[结果]1日龄的尖吻鲈全长1.70±0.10 mm,其身体细长笔直,骨骼尚未开始骨化,附肢骨骼未出现;3日龄时,尖吻鲈仔鱼脊索发生自然弯曲并开始发育,胸鳍、尾鳍原基逐渐形成;5日龄时,尖吻鲈仔鱼脊索末端开始向上弯曲,背鳍开始发育;9日龄时,尖吻鲈仔鱼脊索出现弯曲,髓弓和脉弓开始形成,尾杆骨上翘,随之形成尾鳍,胸鳍原基、背鳍鳍皱开始出现,臀鳍开始发育;13日龄时,尖吻鲈仔鱼的胸鳍和尾鳍发育基本完成,髓棘、脉棘开始出现;15日龄时,尖吻鲈仔鱼的腹鳍开始发育,背肋和腹肋以软骨的形式生长,尾杆骨收缩,背鳍和胸鳍进入发育后期;19日龄时,尖吻鲈仔鱼脊柱骨化,胸鳍出现鳍棘,附肢骨骼发育接近完全;21日龄时,尖吻鲈仔鱼的背肋和腹肋开始骨化,尾鳍骨化基本完成,髓弓、脉弓、髓棘和脉棘也开始骨化;23日龄时,尖吻鲈仔鱼脊柱骨化完全,胸鳍发育完成,鱼体骨骼基础框架完成发育,鳍条开始骨化并出现分节,仔鱼完成变态.脊柱畸形首次出现在10日龄的尖吻鲈仔鱼中,至22日龄时畸形率占样本采集总量的8%,其中前期畸形的仔鱼在14~15日龄时基本被淘汰.[结论]尖吻鲈仔鱼脊柱及附肢骨的发育顺序与其他鱼类基本一致,但发育时间节点有所不同.尖吻鲈仔鱼的骨骼发育畸形首次出现在10日龄左右,但主要集中在20~22日龄. 相似文献
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15.
Regulation of chloride channels by protein kinase C in normal and cystic fibrosis airway epithelia 总被引：21，自引：0，他引：21
M Li J D McCann M P Anderson J P Clancy C M Liedtke A C Nairn P Greengard M J Welsch 《Science (New York, N.Y.)》1989,244(4910):1353-1356
Apical membrane chloride channels control chloride secretion by airway epithelial cells. Defective regulation of these channels is a prominent characteristic of cystic fibrosis. In normal intact cells, activation of protein kinase C (PKC) by phorbol ester either stimulated or inhibited chloride secretion, depending on the physiological status of the cell. In cell-free membrane patches, PKC also had a dual effect: at a high calcium concentration, PKC inactivated chloride channels; at a low calcium concentration, PKC activated chloride channels. In cystic fibrosis cells, PKC-dependent channel inactivation was normal, but activation was defective. Thus it appears that PKC phosphorylates and regulates two different sites on the channel or on an associated membrane protein, one of which is defective in cystic fibrosis. 相似文献
16.
The autonomic nervous system, which includes the sympathetic neurons and adrenal medulla, originates from the neural crest. Combining avian blood vessel-specific gene manipulation and mouse genetics, we addressed a long-standing question of how neural crest cells (NCCs) generate sympathetic and medullary lineages during embryogenesis. We found that the dorsal aorta acts as a morphogenetic signaling center that coordinates NCC migration and cell lineage segregation. Bone morphogenetic proteins (BMPs) produced by the dorsal aorta are critical for the production of the chemokine stromal cell-derived factor-1 (SDF -1) and Neuregulin 1 in the para-aortic region, which act as chemoattractants for early migration. Later, BMP signaling is directly involved in the sympatho-medullary segregation. This study provides insights into the complex developmental signaling cascade that instructs one of the earliest events of neurovascular interactions guiding embryonic development. 相似文献
17.
用Nissl氏法、Weil氏法和Golgi—Cox氏法染色的猪脑干额状面,矢状面和水平面连续切片研究了猪中脑中央灰质(CG)的形态和构筑。猪CG根据细胞的形态、大小、密度及神经纤维的走向可分为四部和一个核:①内侧部,包围中脑水管,②背侧部,位于内侧部的背侧;③腹侧部,位于内侧部的腹侧;④外侧部,在背侧部和腹侧部之间,位于内侧部的外侧;⑤背外侧缘核,呈楔形嵌于外侧部的背外侧缘。 相似文献
18.
目的:探讨小鼠胚胎中脑分离神经干细胞的体外培养方法,以获取高纯度的神经干细胞,为神经干细胞的深入研究提供试验材料。方法:无菌条件下分离孕12~13 d小鼠胚胎中脑曲,制成单细胞悬液,碱性成纤维生长因子(bFGF)和B27存在的培养基中培养扩增,通过免疫细胞化学染色鉴定神经干细胞及子代细胞的分化方向,流式细胞术检测TH阳性神经元比例。结果:培养的部分细胞体外分裂增殖,同时表达神经干细胞特异性抗原nestin,并向神经细胞和胶质细胞分化并经流式细胞仪检测自然分化为多巴胺能神经元的比例为3.25%。结论:小鼠胚脑中脑存在具有多分化潜能的神经干细胞,它们能在体外稳定培养、传代和分化。 相似文献
19.
It is a fundamental principle of vertebrate neuronal organization that sensory fibers are restricted to dorsal roots and motor fibers to ventral roots. Recent evidence, however, indicates that there are many sensory fibers in ventral roots. The present report shows that stimulation of these fibers activates neurons in the dorsal horn. This provides evidence at the single-cell level for the importance of ventral root afferents and provides an explanation for the clinical phenomenon of recurrent sensibility. 相似文献
20.
P35 is a calcium- and phospholipid-binding protein that was originally isolated as a substrate for the epidermal growth factor (EGF) receptor tyrosine kinase and later was found to be related to lipocortin I. Immunohistochemistry was used to localize p35 to a raphe of primitive glial ependymal cells in the median one-third of the floor plate in the central nervous system (CNS) of rat embryos. The p35 appears by embryonic day 12 before the arrival of pioneering ventral commissural axons. The unexpected, discrete distribution of this protein during development opens the question of its role in neural morphogenesis. 相似文献