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71.
72.
印楝茎尖组织培养的研究 总被引:4,自引:0,他引:4
印楝是世界公认的能提炼无公害生物农药的优良植物.对印楝茎尖组织培养与快速繁殖技术研究,可最大限度保持母株优良特性,为实现印楝优良无性系工厂化育苗打下坚实基础. 相似文献
73.
74.
福田红树林桐花树和秋茄的生长过程研究 总被引:2,自引:0,他引:2
对深圳福田红树林群落两个优势种桐花树(Aegicerascorniculatum)和秋茄(Kandeli-acandel)进行横剖树干解析,研究这两个树种的胸径、地径、树高、材积生长量的年变化规律及形数年变化规律,结果为:胸径、地径、树高、材积生长量呈镊合状曲线态;其年生长量一般在其最大值的50%~98%之间;各种平均生长量随年龄的增加而平缓地增加,近峰值而未及,可见两树种有相当长的成熟及衰老期,它们的现存年龄为20a左右;两树种的基部形数不随年龄的增加而呈规律性的变化,很难确定其经验形数值 相似文献
75.
云南烟草根结线虫拮抗真菌分离鉴定初报 总被引:8,自引:0,他引:8
从云南省28个县采集152个土样及发病烟根,利用直接分离法和诱集分离法分别从根结线虫卵囊、卵、雌虫和幼虫分离到400株拮抗真菌,它们包括拟青霉属、镰刀菌属、普可尼亚属、木霉属、链格孢属、曲霉属、青霉属、柱孢菌属、茎点霉属、单顶孢属、钩丝孢属、节丛孢属、矛束孢属等21属及一些不产孢的拮抗真菌,其中淡紫拟青霉、厚垣孢普可尼亚菌、尖孢镰刀菌为分离频率最高,约占分离数的60%.卵囊、卵和雌虫寄生真菌种类和数量远远大于二龄幼虫寄生真菌种类和数量,不同县寄生真菌种类和数量差异较大. 相似文献
76.
ZHOUHantao LINQingtong PANWen GAOYuanyuan CHENPan CHENXu LIUBo 《科学通报(英文版)》2004,49(5):456-461
Salt-tolerant gene, CSRG1, which was isolated from a kind of salt-tolerant mangroves, Avicennia marina, constructed the transgenic plasmid, pGAM189/CSRG1. CSRG1, GUS, Kmr and Hyg^r could be transferred into tobacco genome by the ameliorated leaf discs method of agro-bacterium-mediate transformation. Thirteen stable resistant lines were obtained when fifty transgenic explants were selected through 50 mg/L hygromycin and 150 mg/L kanamycin. Assessments of PCR amplification, Southern blot analysis and GUS histochemical staining showed that CSRG1 has been integrated into the genome of the eleven transgenic lines (frequency of transformation was 22%). Northern bolt analysis revealed that CSRG1 had expressed in transgenic lines. The assessments of salt-tolerant ability and photosyn-thetic rates indicated that the survival rate of the transgenic lines is 80%—90% and the transgenic lines could increase by 30%—40% in plant height, even when they were cultivated in MS medium containing 2% NaCl and the total seawater (salinity 24). It is supposed that the special physiologic metabolic pathway formed by the products of CSRG1 can really endow the tobacco plants with the high salt-tolerant ability, not only to Na^ stress, but also to the comprehensive stress of various ions. 相似文献
77.
LIUShiyong ZHANGZhiyuan SONGYechun QIUKejun ZHANGKecheng ANNing ZHOUZheng CAIWenqin YANGHui 《科学通报(英文版)》2004,49(11):1126-1136
The neural stem cells in the anterior subventricular zone (SVZa) mainly generate the progenitors that will differentiate into neurons, and along a highly circumscribed migratory access Rostral migratory stream (RMS), they migrate to the olfactory bulbs (OB). To understand the effects of BMPs on SVZa neural stem cells, in this study BMP4 at various concentrations was used to induce SVZa neural stem cells, and the living cell labeling using BMP4 promotor conjugated with red fluorescence protein showed the expression of BMP4 dynamically. The results demonstrated that low BMP4 doses (1-5 ng/mL) promoted while high doses (10-100 ng/mL) inhibited the proliferation of SVZa neural stem cells, and BMP4 promotedneuron differentiation in the early stage (1-3 d), howeverm, it inhibited the neuron commitment after 4 d. Noggin, the antagonist of BMP4, blocked the physiological effects of BMP4. In OB, BMP4 is mainly to accelerate the progenitors to withdraw from the cell cycle and trigger the differentiation, and in RMS, it promotes the proliferation of committed progenitors and not differentiation, further in SVZa, BMP4 enhances astrocyte commitment. 相似文献
78.
Isolation of human epidermal stem cells by adherence and the reconstruction of skin equivalents 总被引:47,自引:0,他引:47
Kim DS Cho HJ Choi HR Kwon SB Park KC 《Cellular and molecular life sciences : CMLS》2004,61(21):2774-2781
The isolation of human epidermal stem cells is critical for their clinical applications. In the present study, we isolated three populations of epidermal keratinocytes according to their ability to adhere to collagen type IV: i.e., rapidly adhering (RA), slowly adhering (SA), and non-adhering (NA) cells. The aim of this study was to characterize RA cells and to investigate the possibility of using these cells for epidermis reconstruction. To identify RA cells, flow cytometric analysis was performed using anti-6 integrin and anti-CD71 antibodies. RA cells express high levels of 6 integrin and low levels of CD71, which are considered as markers of an epidermal stem cell nature. Furthermore, electron microscopy showed that RA cells are small and have a high nuclear to cytoplasmic ratio, whereas SA and NA cells have well-developed cellular organelles and abundant tonofilaments. Western blot analysis showed that RA cells are slow cycling and express p63, a putative epidermal stem cell marker, whereas SA and NA cells express c-Myc, which is known to regulate stem cell fate. To compare epidermal regenerative abilities, skin equivalents (SEs) were made using RA, SA, and NA cells. The epidermis constructed from RA cells was well formed compared to those formed from SA or NA cells. In addition, only SEs with RA cells expressed 6 integrin and 1 integrin at the basal layer. These results indicate that RA cells represent epidermal stem cells and are predominately comprised of stem cells. Therefore, the isolation of RA cells using a simple technique offers a potential route to their clinical application, because they are easily isolated and provide a high yield of epidermal stem cells.Received 2 July 2004; received after revision 20 August 2004; accepted 10 September 2004 相似文献
79.
Culture in low levels of oxygen enhances in vitro proliferation potential of satellite cells from old skeletal muscles 总被引:4,自引:0,他引:4
Chakravarthy MV Spangenburg EE Booth FW 《Cellular and molecular life sciences : CMLS》2001,58(8):1150-1158
The proliferation ability of satellite cells (considered the 'stem cells' of mature myofibers) declines with increasing age
when cultured under standard cell culture conditions of 21% oxygen. However, actual oxygen levels in the intact myofiber in
vivo are an order of magnitude lower. No studies to date have addressed the issue of whether culturing satellite cells from
old muscles under more 'physiologic' conditions would enhance their proliferation and/or differentiation ability. Therefore,
we analyzed satellite cells derived from 31-month-old rats in standard cultures with 21% O2 and in lowered (∼3%) O2. Under the lowered O2 conditions, we noted a remarkable increase in the percentage of large-sized colonies, activation of cell cycle progression
factors, phosphorylation of Akt, and downregulation of the cell cycle inhibitor p27Kip1. These data suggest that lower O2 levels provide a milieu that stimulates proliferation by allowing continued cell cycle progression, to result ultimately
in the enhanced in vitro replicative life span of the old satellite cells. Such a method therefore provides an improved means
for the ex vivo generation of progenitor satellite cell populations for potential therapeutic stem cell transplantation.
Received 20 April 2001; received after revision 28 May 2001; accepted 31 May 2001 相似文献
80.
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