。基因芯片技术可大规模地检测和分析DNA的 变异及多态性。Wang等应用高密度基因芯片对2.3Mb人类基因的SNP 进行筛查,确 定了3241个SNPs位点,显示出大规模鉴定人类基因型的可能[22]。Lipshutz等人 采用含18,495个寡核苷酸探针的微阵列,对HIV-1基因组反转录酶基因(rt)及蛋白 酶基因(pro)的高度多态性进行了筛选,这些变异将导致病毒对多种抗病毒药物包 括AZT、ddI、ddC等表现出抗性,因此rt与pro的变异与多态性的检测具有重要的临 床意义[23]。随着大量疾病相关基因的发现,变异与多态性分析将在疾病的诊断 与治疗方面体现出越来越重要的价值。Affymetrix公司已将P53 基因的全长序列和 已知突变的序列制成探针集成在芯片上,可对与P53 基因突变相关的癌症进行早期 诊断。Hacia等采用含96600个20聚寡核苷酸高密度阵列对遗传性乳腺和卵巢癌BRC A1基因3.45kb的第11个外显子进行杂合变异筛选[12],结果准确诊断出15个已知 变异的患者样品中的14个,而在20个对照样品中未发现1例假阳性,表明DNA芯片技 术在某些疾病相关基因可能的杂合变异的检测方面所具有的灵敏度与特异性是令人 满意的。 芯片技术中杂交测序技术(sequencing by hybridization,SBH)是一种新的 高效快速测序方法,也是基因芯片的另一重要应用[24],其原理与芯片检测多态 位点相类似,即通过与一组已知序列的核酸探针杂交进行序列测定,用荧光标记的 待测序列与基因芯片上对应位置的核酸探针产生互补配对时,通过确定荧光强度最 强的探针位置,获得一组序列互补的探针序列,据此可重组出靶核酸的序列。用含 65536个8聚寡核苷酸的微阵列,采用SBH技术,可测定200bp长DNA序列,采用6710 8864个13聚寡核苷酸的微阵列,可对数千个碱基长的DNA测序。 3 结束语 基因芯片技术的出现不过短短几年时间,其发展势头十分迅猛,在生命科学的 各个领域得到广泛地应用,但其存在的缺陷也是相当明显的。首先是成本的问题, 由于芯片制作的工艺复杂,信号检测也需专门的仪器设备,一般实验室难以承担其 高昂的费用,其次在芯片实验技术上还有多个环节尚待提高,如在探针合成方面, 如何进一步提高合成效率及芯片的集成程度是研究的焦点。而样品制备的简单化与 标准化则芯片应用进一步普及的前提。虽然芯片技术还存在这样或那样的问题,但 其在基因表达谱分析、基因诊断、药物筛选及序列分析等诸多领域已呈现出广阔的 应用前景,随着研究的不断深入和技术的更加完善基因芯片一定会在生命科学研究 领域发挥越来越重要的作用。 [参考文献] [1] Cheung V G,Morley M,Aguilar F et al.Making and reading microarra ys[J].Nature Genetics(Supplement),1999,21∶15. [2] 张思仲.人类基因组的单核苷酸多态性及其医学应用[J].中华医学遗传学 杂志,1999,16∶119. [3] Marshall A and Hodgson J. DNA chips: An array of possibilities[ J].Nature Biotechnology,1998,16∶731 . [4] Ramsay R. DNA chips: State-of-the-art[J].Nature Biotechnology, 1998,16∶40. [5] Lipshutz R, Fodor S ,Gingeras T,et al. High density synthetic ol igonucleotide arrays[J].Nature Genetics(Supplement),1999,21∶20. [6] Prpndnikov D, Timofeev E, Mirzabekov A.Immobilization of DNA in Polyacrylamide gel for the manufracture of DNA chip and oligonucleotide Microchips[J],Anal Biochem,1998,259∶34. [7] McGall GH,Barone AD,Diggelmann M,et al. The efficiency of lig ht- directed synthesis of DNA arrays on glass substrates[J].J Am Chem Soc,1997,119(22)∶5081. [8] Pease AC, Solas D, Sullivan EJ, et al. Light-generated oligonucl eotide arrays for rapid DNA sequence analysis[J].Proc Natl Acad Sci U SA, 1994,91∶5022. [9] Fodor S,Read L, Pirrung M et al.Light-directed,spatially addres sable parallel chemical synthesis[J].Science,1991,251∶767. [10] Beecher,Jody E.,McGall,Glenn H.,et al. Chemically amplified photolithography for the fabrication of high density oligonucleotide a ssays[J].Polym Mater Sci Eng,1997,76∶597. [11] Schena,M,Shalon,D,Davis,RW,et al. Qantitative monitoring of gene expression patterns with a complementary DNA microarray[J].Sc ience,1995, 270∶467. [12] Hacia J,Brody L,Chee M, et al.Detection of heterozygous mutatio ns in BRCA1 using high density oligonucleotide arrays and two-color flu orescence Analysis[J].Nat Genet,1996, 14∶441. [13] Hacia J ,Edgemon K,Sun B et al.Two color hybridization analysi s using high density oligonucleotide arrays and energy transfer dyes[J ].Nucleic Acids Res,1998, 26∶4249. [14] Hacia J.Resequencing and mutation analysis using oligonucleotid es microarrays [J].Nature Genetics(Supplement),1999,21∶42. [15] Wodicka L,Dong H,Mittmann M,et al.Genome-wide expression moni toring in Saccharomyces cerevisiae[J].Nature Biotechnology,1997,15∶1 359. [16] Lockhart DJ,Dong H,Byrne MC,et al. Expression monitoring by hybridization to high-density oligonucleotide arrays[J].Nature Biotec hnology ,1997,14∶1675. [17] DeRisi J,Penland L,Brown PO,et al. Use of a cDNA microarray to analysis gene expression patterns in human cancer[J].Nat Genet,199 6,14∶457. [18] Brown P O, Botstein D.Exploring the new world of genome with DN A microarrays[J].Nature Genetics(Supplement),1999,21∶33. [19] Jelinsky S and Samson L.Global response of Saccharomyces cerevi siae to a alkylating agent ,proc[J].Natl Acad Sci USA,1999,96∶1486. [20] Golub T, Slonim D, Tamayo P, et al, 1999, Molecular Classificat ion of cancer: Class Discovery and Prediction by Gene Expression Monito ring[J].Science,1999,286∶531. [21] Heller RA, Schena M, Chai A, et al.Discovery and analysis of in flammatory disease-related genes using cDNA microarrays[J].Proc Natl Acad Sci USA,1997,94∶2150. [22] Wang D, Fan J, Siao C et al.Large-scale identification, mapping and genotyping of single-nucleotide polymorphism in human genome[J]. Science,1998,280∶1077. [23] Lipshutz RJ, Morris D, Chee M, et al. Using oligonucleotide pro be arrays to access genetic diversity[J].Bio Feature,1995,19(3)∶442. [24] Wallraff G,Labadie J,Brock P,et al. DNA Sequencing on a Chip [J].Chemtech,1997,22∶32.
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