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941.
ZHANGJingpu WANGWeixian ZHUShaoxia 《科学通报(英文版)》2004,49(7):683-688
Interaction between nucleus and cytoplasm has been focused in the field of animal embryonic development, in which study of maternal factors is required positively. β-Catenin, an important maternal factor in early embryogenesis, has been analyzed in its expression pattern and functions in this paper. We have cloned goldfish β-Catenin cDNA gene and compared it with zebrafish β-Catenin cDNA. High homology was found in cDNA and in amino acid sequences between them, 93% (2227/2384 bp) and 98.5% (768/780 aa) respectively. The expression pattern of β-Catenin by in situ hybridization and the roles of β-Catenin on embryonic development by co-injection of anti-sense RNA and reporter gene, EGFP have been investigated in the whole process of goldfish embryonic development. The results suggest that β-Catenin presents dynamic distribution, mainly locates at body axis, dorsal tissues, head and tail structures after being fertilized. The loss of β-Catenin activity would cause serious destruction of embryo in dorsal tissues and in anteroposterior axes, and leads embryos to die before larva get hatched. 相似文献
942.
Davoli C Marconi A Serafino A Iannoni C Marcheggiano A Ravagnan G 《Cellular and molecular life sciences : CMLS》2002,59(3):527-539
Nerve growth factor (NGF) belongs by sequence homology to the neurotrophins, a family of proteins binding the same p75 receptor
and closely related members of the Trk family of receptor tyrosine kinases. Fundamental in the vertebrate nervous system,
neurotrophin signals have also been suggested as essential for relatively complex nervous systems occurring in invertebrate
species that live longer than Caenorhabditis elegans and Drosophila melanogaster. Mammalian neurotrophins have been found to influence invertebrate neuronal growth. However, there are only a few data on
the presence of molecules related to neurotrophin signalling components in invertebrates. Our studies provide evidence that
analogues of neurotrophins and neurotrophin receptors are expressed in Eisenia foetida earthworms. In particular, NGF-like and Trk-like immunoreactive proteins are both expressed in the nervous system, whereas
p75-like positivity identifies tubular structures associated with dorsal pores that are involved in the earthworm response
to mechanical irritation or stress.
Received 12 November 2001; received after revision 8 January 2002; accepted 8 January 2002 相似文献
943.
移动卫星通信星座工程设计 总被引:4,自引:2,他引:2
在考虑许多的约束条件的情况下,研究了一个工程上可实现的轨道和星座设计方法。详细分析了移动卫星通信星座在工程设计时,就轨道参数、星座参数选择时所需考虑的在星体指标、通信要求、覆盖性能、发射及测控、经济等方面的约束条件,并进行综合考虑和优化设计。在此基础上,给出了一个星座通信系统的空间段设计,经专家评审该星座方案在工程实现上是可行的。 相似文献
944.
Joyce S 《Cellular and molecular life sciences : CMLS》2001,58(3):442-469
Cellular and humoral immune mechanisms recruited to defend the host from infectious agents depend upon the early immune events
triggered by antigen. The cytokine milieu within which the immune response matures is the most important of many factors that
govern the nature of the immune response. Natural T cells, whose function is controlled by CD1d molecules, are an early source
of cytokines that can bestow type 1 or type 2 differentiative potential upon helper T lymphocytes. This review attempts to
illuminate the glycolipid antigen presentation properties of CD1d, how CD1d controls the function of natural T cells and how
CD1d and natural T cells interact to jump start the immune system. CD1d is postulated to function as a sensor, sensing alterations
in cellular lipid content by virtue of its affinity for such ligands. The presentation of a neo-self glycolipid, presumably
by infectious assault of antigen-presenting cells, activates natural T cells, which promptly release pro-inflammatory and
anti-inflammatory cytokines and jumpstart the immune system.
Received 10 July 2000; received after revision 16 October 2000, accepted 16 November 2000 相似文献
945.
The neurotrophic factors in non-neuronal tissues 总被引:17,自引:0,他引:17
Sariola H 《Cellular and molecular life sciences : CMLS》2001,58(8):1061-1066
Although neurotrophic factors are defined as molecules that maintain neuronal cells, they possess a range of functions outside
the nervous system. For example, glial cell line-derived neurotrophic factor is essential for ureteric branching in kidney
morphogenesis and for regulating the fate of stem cells during spermatogenesis. Leukemia inhibitory factor, a member of the
interleukin-6 (IL-6) ciliary neurotrophic factor family, inhibits differentiation of embryonic stem cells, induces tubulogenesis
in the embryonic kidney, and regulates sperm differentiation. Other IL-6 family members are important in cardiac differentiation
and they have pleiotropic functions in the hematopoietic and immune systems. Although neurotrophin receptors have been found
on a number of non-neuronal tissues, they represent mostly truncated receptor isoforms that are incapable of signal transduction
and may have scavenger or dominant negative functions. However, several examples can be presented of essential non-neuronal
functions played by neurotrophins in e.g., cardiac, hair follicle, and vascular differentiation, and the maintenance of immune
cells. 相似文献
946.
Penkowa M Espejo C Martínez-Cáceres EM Montalban X Hidalgo J 《Cellular and molecular life sciences : CMLS》2003,60(1):185-197
Metallothioneins I+II (MT-I+II) are antioxidant, neuroprotective factors. We previously showed that MT-I+II deficiency during
experimental autoimmune encephalomyelitis (EAE) leads to increased disease incidence and clinical symptoms. Moreover, the
inflammatory response of macrophages and T cells, oxidative stress, and apoptotic cell death during EAE were increased by
MT-I+II deficiency. We now show for the first time that demyelination and axonal damage are significantly increased in MT-I+II
deficient mice during EAE. Furthermore, oligodendroglial regeneration, growth cone formation, and tissue repair including
expression of trophic factors were significantly reduced in MT-I+II-deficient mice during EAE. Accordingly, MT-I+II have protective
and regenerative roles in the brain.
Received 31 October 2002; received after revision 23 November 2002; accepted 26 November 2002
RID="*"
ID="*"Corresponding author. M. Penkowa and C. Espejo contributed equally to this paper. 相似文献
947.
GFP标记的GDNF重组腺病毒载体的构建和体内外表达 总被引:2,自引:0,他引:2
通过构建绿色荧光蛋白(GFP)和胶质细胞源性神经营养因子(GDNF)共表达的腺病毒载体,讨论其在治疗脊髓和脑有关神经系统疾病的潜在应用价值,了解腺病毒载体在大鼠体内的分布及在体外分泌外源基因产物能力,并对其生物安全性作了初步考察,为GDNF重组腺病毒载体在临床和基础研究中的应用作了一定准备. 相似文献
948.
动态误差时间序列小波神经网络预测模型 总被引:1,自引:1,他引:0
基于现代误差修正技术,研究小波神经网络建立的动态测量误差预测模型,以进行误差修正,提高动态测量精度,避免了传统神经网络需要人为干预网络结构参数的不足。文章介绍了建模方法,重点对大轴圆度误差测量过程中的动态测量数据进行实例分析,结果表明,该模型预测精度高,具有重要的应用价值。 相似文献
949.
950.