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91.
为研究染色体外重组方法在创建转基因动物中的应用,选取牛asl酪蛋白基因的5′及3′侧翼区和氯霉素乙酰化酶编码区,构建了两个具有3 kb相互重叠的融合基因.将这两个DNA片段末端脱磷酸后,以摩尔比1:1的比例混合,通过显微注射导入小鼠受精原核,最后获得了11个品系的转基因小鼠.对其中10个品系的小鼠的整合分析表明,所注射的两个DNA片段均发生了染色体外同源重组,而且除了 1个品系的小鼠丢失了大约1kb的序列外,其余品系小鼠的重组产物与预想的结构符合.在当代和后代的转基因小鼠乳汁中均可测到氯霉素乙酰化酶的活性.这表明融合基因在转基因小鼠乳腺中得到表达和分泌,也说明显微共注射两个相互重叠的基因片段是建立转基因动物的一个可行途径. 相似文献
92.
Cysteine sulfinic acid decarboxylase (CSAD), the rate-limiting enzyme in taurine biosynthesis, appears to be present in the brain in multiple isoforms. Two distinct forms of CSAD, referred to as CSAD I and CSAD II, were obtained on Sephadex G-100 column. CSAD I and CSAD II differ in (1) the elution profile on Sephadex G-100 column; (2) the sensitivity towards Mn2+, methione, and other sulfur-containing amino acids and (3) their immunologic properties. CSAD II has been purified to about 2,500-fold by a combination of column chromatographies and polyacrylamide gel electrophoresis (PAGE). The purity of the enzyme preparation was established as judged from the following observations: (1) a single protein band was observed under various electrophoretic conditions, e.g., 5–20% nondenaturing PAGE, 7% nondenaturing PAGE and 10% SDS-PAGE and (2) in nondenaturing PAGE, the protein band comigrated with CSAD activity. CSAD II has a molecular weight of 90 kDa and is a homodimer consisting of two 43 ± 2 kDa subunits. CSAD appears to require Mn2+ for its maximum activity. Other divalent cations fail to replace Mn2+ in activation of CSAD activity. However, the precise role of Mn2+ in the action of CSAD remains to be determined. 相似文献
93.
Hyun Koo Kim Moon Sun Ham Jong Soo Hong Jin Ha Lee Kyung Yu Park Hyeon Yong Lee 《Biotechnology and Bioprocess Engineering》1996,1(1):32-35
A moving aeration-membrane (MAM) bioreactor was employed for the production of 2 μg/mL of tissue type Plasminogen Activator (tPA) in serum free medium from normal human fibroblast cells. This system could maintain high cell density for long periods of steady state conditions in perfusion cultivation. Under normal operating conditions, shear stress was as low as 0.65 dynes/cm2 at the agitation speed of 80 rpm. Even though cell density gradually decreased with increasing agitation speed, tPA production increased linearly with increasing shear stress within a moderate range. This culture system allowed production of 2 μg tPA/mL while maintaining a high cell density of 1.0×107 viable cells/mL. 相似文献
94.
Yong Xu Wallace G. Buchholz Richard T. DeRose Timothy C. Hall 《Plant molecular biology》1995,27(2):237-248
Two cDNA clones (RCc2 and RCc3) corresponding to mRNAs highly expressed only in root tissues of rice (Oryza sativa L.) seedlings were characterized. Respectively, they encode polypeptides of 146 (14.5 kDa) and 133 amino acids (13.4 kDa) that share high (<70%) sequence similarity with a polypeptide encoded by a cDNA (ZRP3) encoding an mRNA preferentially expressed in young maize roots. Genomic DNA blot analysis revealed that they are members of a small gene family and RCg2, the gene corresponding to RCc2, was isolated. A 1656 bp 5-upstream sequence of RCg2 was translationally fused to a -glucuronidase (GUS) reporter gene and stable introduction of the chimeric construct into rice was confirmed by PCR and genomic DNA blot analyses. Histochemical analysis of transgenic rice plants containing the full-length chimeric gene showed high levels of GUS activity in mature cells and the elongation and maturation zones of primary and secondary roots, and in the root caps, but no GUS activity was detected in root meristematic regions. Surprisingly, high GUS activity was also detected in leaves of the same plants. This raises the possibility that the RCg2 5-upstream element may not be sufficient for the proper spatial control of root specificity in transgenic rice. 相似文献
95.
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97.
Hyung-Joo Jin Jeong–Ha Kim Chul Hyun Sohn R.E. DeWreede Tae–Joo Choi G.H.N. Towers J.B. Hudson Yong–Ki Hong 《Journal of applied phycology》1997,9(4):383-388
Fifty-nine species of marine macrophytes from the coasts of British Columbia, Canada and Korea have been screened for the
presence of PCR inhibitors, namely inhibitors of Taq DNA polymerase. Eleven of the species displayed some inhibitor activity.
At the concentration of 5 μg of methanol extract in 25μL reaction mixture of PCR containing 1.5 unit of Taq DNA polymerase,
one (Ulva sp.) of 8 Chlorophyta, eight (Colpomenia bullosa, Ecklonia cava, Endarachne binghamiae, Fucus distichus, Hizikia
fusiformis, Sargassum confusum, Sargassum sagamianum, and Sargassum thunbergii) of 28 Phaeophyta, and one (Symphyocladia latiuscula)
of 34 Rhodophyta showed inhibition in PCR amplification. In the case of the water extract, two (Cladophora columbiana, Ulva
sp.) Chlorophyta, seven (Endarachne binghamiae, Fucus distichus, Hizikia fusiformis, Sargassum confusum, Sargassum sagamianum,
Sargassum horneri, Scytosiphon dotyi) Phaeophyta, no Rhodophyta and one (Phyllospadix scouleri) seagrass showed inhibition
in PCR amplification. the methanol fraction of Sargassum confusum and the water fraction of Fucus gardneri (mid–intertidal)
have been found to inhibit PCR at level as low as 0.5 μg in 25μL of PCR reaction mixture.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
98.
描述了产自四川自贡大山铺恐龙化石坑中的三件龟甲标本,命名为一新属新种—周氏四川龟(Sichuanchelyschowigen.etsp.nov.)。该属以椎盾极横宽,中部缘盾极狭长为主要特征,它代表了成渝龟科中一类较特别的类型。 相似文献
99.
用电内渗不同(0、0.03、0.08、0.20mr)的琼脂糖制成凝胶或电极缓冲液凝胶条,观察对电泳行为的影响.结果表明等电聚焦电泳必须使用无电内渗琼脂糖.不同电内渗的琼脂糖制成的电极缓冲液凝胶条对SDS电泳无显著影响,但对常规聚丙烯酰胺凝胶电泳有不同程度的影响,电内渗越高,越不利于电泳的进行. 相似文献
100.
赤霉素与脱落酸对番茄种子萌发中细胞周期的调控 总被引:11,自引:0,他引:11
利用细胞流检仪检测番茄(Lycopersicon esculentum Mill.) GA-缺陷型、ABA-缺陷型和相应的正常品种(野生型)成熟种子胚根尖细胞倍性水平时发现:GA-缺陷型和野生型种子绝大多数细胞DNA 水平为2C,而ABA-缺陷型种子则含有较多的4C细胞。在标准发芽条件下,ABA-缺陷型和野生型种子浸种1 d 后胚根尖细胞DNA 开始复制,随后胚根突破种皮而发芽。然而GA-缺陷型种子除非加入外源GA,否则既不发生细胞DNA 复制,也不发芽。这说明内源GA 是启动番茄种子胚根尖细胞DNA 复制的关键因素,同时也说明番茄根尖细胞DNA 复制是种子发芽的必要条件。实验证明:ABA 不抑制细胞DNA 合成,但阻止G2 细胞进入到M 期。外源ABA处理野生型种子与渗控处理结果相似,可以大幅度提高胚根尖4C/2C细胞的比例,但抑制种子的最终发芽 相似文献