Aptamers are small DNA ligands that have been manually selected to strongly and specifically bind a target of interest. These molecules may prove superior to modern antibodies in a number of ways including price and reproducibility. One of the major advantages of using aptamers as opposed to antibodies is the relative speed of development. This, coupled with the repetitive nature of aptamer selection, means that the entire process is a possible target for automation. In the following experiments, a ssDNA aptamer is developed against the human red blood cell protein glycophorin A, partially through the novel use of a robotized benchtop. The process also utilizes an adapted protocol for emulsion PCR to further increase the efficiency of the selection process. After 11 rounds of selection, the DNA pools were sequenced leading to the generation of 14 potential aptamers. These aptamers were tested with the isolated protein and with human red blood cells resulting in several of the aptamers being deemed potential binders. Further work with these identified sequences could result in aptamers that can be reliably used to tag and delicately separate red blood cells from other cells of interest within blood, such as stem cells. The novel approaches to selection used in this work may also lead to quicker and more efficient generation of future aptamers.

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Orientador: Lilian Maria de Castilho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faucldade de Ciencias Medicas / Made available in DSpace on 2018-08-12T08:43:08Z (GMT). No. of bitstreams: 1 Omoto_Ricardo_M.pdf: 806455 bytes, checksum: 919c6c6ffefecaf298fe52f6907eabfc (MD5) Previous issue date: 2008 / Resumo: Introdução: As bases moleculares responsáveis pelas variantes do gene GYPB ainda não estão estabelecidas para a população de Brasileiros descendentes de Africanos. O presente estudo foi realizado para analisar os mecanismos moleculares que originam o fenótipo S-s- e determinar a frequência do gene GYPB*S silencioso no fenótipo S-s+, em uma população de doadores de sangue descendentes de Africanos. Materiais e Métodos: Foram selecionadas 165 amostras de sangue de Brasileiros descendentes de Africanos (Nordeste do Brasil) fenotipados como S-s- (n=17) e S-s+ (n=148) por hemaglutinação. Com a finalidade de identificar as formas variantes do gene GYPB, realizamos a genotipagem dessas amostras pelas técnicas de PCR Alelo-específico (AS-PCR) e PCR-RFLP. Resultados: Em 13 das 17 amostras S-s- (76,5%) ambos os alelos GYPB*S e GYPB*s estavam deletados. Em 137 das 148 amostras fenotipadas como S-s+ (92,6%), o resultado da genotipagem pela técnica AS-PCR foi consistente com o fenótipo S-s+. Em 4 das amostras S-s- (23,5%) e em 11 das amostras S-s+ (7,4%) foi identificada a presença do alelo GYPB*S associado com o silenciamento do antígeno S. Das amostras de DNA de doadores com o fenótipo S-s- que demonstraram a presença do alelo GYPB*S, 2 apresentaram a variante GYP(P2), 1 a variante GYP(NY) e, em 1 amostra encontramos ambas as formas variantes de GYPB: GYP(P2) e GYP(NY) Em 11 doadores com o fenótipo S-s+ houve heterozigosidade para o alelo GYP(P2) (n=8) e heterozigosidade para o alelo GYP(NY) (n=3). Conclusão: Esse estudo relata pela primeira vez os mecanismos moleculares responsáveis pelo fenótipo S-s- em uma população de Brasileiros descendentes de Africanos e promove o conhecimento de uma nova informação sobre a frequência (7,4%) e as bases moleculares do gene GYPB*S silencioso nesta população. / Abstract: Background: The molecular background of variant forms of GYPB is not well studied in Brazilians of African descent. The present study was carried out to determine the molecular bases of the S-s- phenotype and the frequency of GYPB*S silent gene for the S-s+ phenotype in a blood donor population of African Brazilians. Methods: We selected 165 blood samples from African Brazilians (Northeastern Brazil) who phenotyped as S-s- (17) and S-s+ (148) by hemagglutination. AS-PCR and PCR-RFLP were used to identify the variant forms of GYPB. Results: In 13 of 17 S-s- samples (76.5%) both GYPB were deleted. In 137 of the 148 S-s+ samples (92.6%), the AS-PCR was consistent with the S-s+, phenotype. In 4 of the S-s- samples (23.5%) and 11 of the S-s+ samples (7.4%) showed the presence of the GYPB*S allele associated with silencing of the S antigen. In the 4 donors with the S-s- phenotype there was homozygosity (or hemizygosity) for the GYP(P2) allele (n=2), homozygosity (or hemizygosity) for the GYP(NY) allele (n=1) and heterozygosity for the GYP(P2) and GYP(NY) alleles (n=1). In the 11 donors with the S-s+ phenotype there was heterozygosity for GYP(P2) allele (n=8) and heterozygosity for GYP(NY) allele (n=3). Conclusion: This study reports for the first time the molecular mechanisms responsible for the S-s- phenotype in a population of African Brazilians and provides a new information about the frequency and molecular bases of GYPB*S silent gene (7.4%) in this population. / Mestrado / Clinica Medica / Mestre em Clinica Medica