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癌症患者的最大威胁来自肿瘤的转移,若能控制肿瘤的转移,癌症对人类的最大威胁就会消除,也就是癌症可作为一种慢性疾病来治疗。如何控制癌症的转移?这成为癌症研究和治疗的中心问题。以前对肿瘤的转移研究主要集中在肿瘤细胞本身,现在看来这是不够的,目前已经把研究的目光转移到肿瘤的生态环境或微环境。人们已经知道肿瘤的发生和生长是由多种细胞、因子和外界因素协同作用而产生的,它生存在一个非常复杂的生态坏境(即 相似文献
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今年本刊第一期(中国细胞生物学学报2011;33(1):95-9.)我介绍了美国科学家克雷格·文特尔实验室人工合成支原体基因组,创造了人造生命体。这个基因组长度为1.08 Mb,用化学方法合成了该基因组所有的DNA片段,然后借助酵母同源重组技术将这些片段组装成完整的支原体基因组(环形 相似文献
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Angiostatin是一种新发现的对肿瘤生长有特异抑制作用的抗血管生成因子,实验已证实其对多种肿瘤有明显的抑制作用.本文报告构建了含Angiostatin基因的真核表达载体pAG3,通过建立荷瘤小鼠模型来研究Angio-statin对人黑色素瘤B16的原位生长,植入及与化疗药物DTIC的联合作用等来探讨Angiostatin裸DNA肌肉注射的体内抗瘤效应.实验结果表明Angiostatin可明显抑制C57荷瘤小鼠的肿瘤生长;人黑色素瘤B16细胞植入前5天肌肉注射pAG3能显著阻止正常C57小鼠新肿瘤的形成;但在pAG3与DTIC联合化疗实验中,两者未表现出明显的增强效应.本实验为拓展非病毒介导的Angiostatin抗血管生成基因治疗途径奠定了基础. 相似文献
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肿瘤可以看作是一种免疫性疾病,即病理性的免疫耐受疾病。正常的(生理性的)免疫耐受是人体重要的防御和维护机制,能保证免疫杀伤功能不伤害自身,也就是不会发生冤假错案。例如,免疫耐受可以保证免疫系统不识别自身细胞和抗原、防御超敏性免疫反应及自身免疫性疾病的发生、保护自身生殖细胞和成体干细胞不受周围免疫系统的干扰、保护胎儿不受母体免疫系统排斥等。病理性的免疫耐受是病原体(例如肝炎病毒)为了长期保持在宿主体内的感染状态或肿瘤细胞为了逃逸免疫的监督, 相似文献
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本刊上一期(中国细胞生物学学报2012;34(4):398–400)介绍了美国《Science》杂志评出的2011年十大科学突破中关于"清除衰老细胞可以延缓衰老性疾病的发生"的内容,本期重点来介绍"人类微生物组研究的新突破"。"人类微生物组(human microbiome)"是指生活在人体内所有微生物(包括原核微 相似文献
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用盒式突变和定点突变对大肠杆菌青霉素G酰化酶α亚基177位ser进行了突变研究,结果发现所挑选的突变体均无酶的活力,这一结果可能可以用来解释Ser 177附近肽段和一些青霉素结合蛋白青霉素结合区在一级结构上保持同源性的原因。 相似文献
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大肠杆菌青霉素G酰化酶基因及其邻近区域的核苷酸全序列 总被引:5,自引:2,他引:3
Some of microorganisms have been known to possess penicillin G acylase activity. The E. coli derived penicillin G acylase (PGA) can catalyze the conversion of penicillin G into phenylacetic acid and 6-amino-penicillanic acid, the latter is used as the starting compound for the industrial formation of semi-synthetic penicillins. Apart from its industrial importance, the enzyme PGA displays a number of interesting properties. Catalytically active enzyme is localized in the periplasmic space of E. coli cells and composed of two dissimilar subunits. The two subunits are apparently produced from a precursor protein, via a processing pathway hitherto unique in its features for a prokaryotic enzyme. The studies on processing of the precursor and on the relationship between structure and function of the mature enzyme are important theoretically. Previously we cloned a 3.5 kb DNA fragment from a strain (E. coli AS 1.76), which displays PGA activity. In this paper, we report a nucleotide sequence of the 3.5 kb DNA fragment containing PGA gene. After insertion of the DNA fragment into EcoR I and Hind III sites in pWR 13, pPGA 20 had been obtained. We subcloned the Hind III and Bg1 II treated fragment of 1.6 kb in length from pPGA 20 into Hind III and BamH I sites of pWR 13 to get a pPGA 1.6, and Bg1 II and EcoR I treated fragment of 1.9 kb in length into BamH I and EcoR I sites of pWR 13 to get a pPGA 1.9. The linearized pPGA 1.9 which were digested with appropriate restriction enzymes were progressively shortened from both ends respectively by digestion with Bal 31 nuclease, followed by cleavage of shortened target DNA off vector DNA molecules with appropriate restriction enzymes. The series of the DNA fragments shortened from EcoR I end were then cloned into plasmid pWR 13 which had previously digested with Hind III and Sma I enzymes (Fig. 1). The DNA fragment cloned in pWR 13 were directly sequenced on the resulted plasmids by using primer I and primer II. Thus we have obtained the complete nucleotide sequence of the 3.5 kb DNA fragment. The 3.5 kb fragment contains an intact PGA gene which is 2.6 kb.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
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DNA双螺旋模型的提出意味着分子生物学的诞生,重组DNA技术的建立标志着遗传工程和生物工程的问世。可以说重组DNA技术对整个生物学研究的影响比起DNA双螺旋来说有过之而无不及。目前世界上从事生物学或医学研究的大多数实验室都在使用这项技术解决不同的生物学问题。许多人衡量一个生物学实验室是否先进总喜欢把是否运用重组DNA技术和基因工程作为一个重要标志。一、重组DNA技术和基因工程概况重组DNA技术和基因工程涉及的内容很广,不仅包括外源DNA和载体的重组,还应 相似文献