Submitted by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2012-08-31T17:18:28Z No. of bitstreams: 1 Thais Ferreira Bonfim. Ancestralidade genômica em uma amostra de portadores do HIV-1 do Estado da Bahia - CPqGM - Dissertação de Mestrado - 2008.pdf: 2375743 bytes, checksum: 3d0b1edd686e7965b81d1f26113f0f78 (MD5) / Made available in DSpace on 2012-08-31T17:18:28Z (GMT). No. of bitstreams: 1 Thais Ferreira Bonfim. Ancestralidade genômica em uma amostra de portadores do HIV-1 do Estado da Bahia - CPqGM - Dissertação de Mestrado - 2008.pdf: 2375743 bytes, checksum: 3d0b1edd686e7965b81d1f26113f0f78 (MD5) Previous issue date: 2008 / Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, Bahia, Brasil / Dados históricos e genéticos mostram que a população brasileira é uma das mais heterogêneas do mundo, fruto de um processo de miscigenação entre os três principais grupos étnicos (ameríndios, europeus e africanos) formadores da nossa população. Entretanto a distribuição desses três grupos ao longo do território brasileiro não ocorreu de forma homogênea, ou seja, a proporção de africanos, ameríndios e europeus difere significativamente a depender da região geográfica. Na Bahia a proporção de afrodescendentes é de 77,5%, segundo autodenominação no censo do IBGE. Poucos trabalhos descrevem a diversidade genética na Bahia e são em sua maioria baseados em marcadores genéticos clássicos. Atualmente tem sido estimada mistura racial e diversidade genética através de marcadores moleculares que apresentam alelos com um diferencial de frequência acima de 30% entre populações geográfica e etnicamente distintas, que são conhecidos como Alelos Específicos de Populações (PSA). Além dos PSA, também são utilizados marcadores culturais, que através da análise de sobrenomes de família, são bastante úteis para inferir origem e mistura racial em populações miscigenadas como a da Bahia. Dados da literatura mostram que há um risco para o desenvolvimento de algumas doenças a depender do grupo étnico, como doenças cardiovasculares e infecciosas, como a AIDS. No Brasil, estima-se que até o final de 2004, o número de indivíduos infectados pelo HIV-1 foi de 362.364. A Bahia é o estado brasileiro que apresenta a 2ª maior incidência de AIDS. É sabido que o curso clínico da infecção pelo HIV-1 é determinado por complexas interações entre as características virais e os fatores do hospedeiro. Para estimarmos a contribuição dos grupos ancestrais nesta população foram analisados 517 indivíduos infectados pelo HIV-1 do estado da Bahia para 10 PSA (AT3-I/D, APO, SB19.3, PV92, FYnull, LPL, CKMM, GC-F, GC-S e CYP3A4) e para 2 marcadores de susceptibilidade ao HIV-1 (CCR5-Δ32 e CCR2-64I). Foram investigadas as condições sócio-econômicas e a ancestralidade destes pacientes através da sua autodenominação e de uma análise fenotípica baseada em caracteres físicos, além disso, analisou-se os sobrenomes de família para identificação de sobrenomes de conotação religiosa. A estimativa de ancestralidade genômica mostrou que a população analisada apresentava uma maior contribuição africana de 48%, seguida da européia (35%) e ameríndia (17%), sendo as proporções bastante similares quando comparadas com a população de Salvador, não infectada pelo HIV-1. A análise fenotípica quando comparada com a autodenominação desses indivíduos, mostrou-se discordantes apenas na caracterização dos indivíduos negros. Encontrou-se também uma associação entre maior frequência de sobrenome de conotação religiosa com o aumento do fenótipo negróide, indicando que a análise de sobrenome é uma ferramenta importante para inferência de ancestralidade africana. A análise sócio-econômica mostrou que a população com menor nível de escolaridade e menor renda familiar tinha maior ancestralidade africana, sugerindo que a ancestralidade está influenciando numa maior susceptibilidade ao HIV/AIDS. Assim, este trabalho foi de grande importância para estimar a proporção de mistura entre grupos ancestrais na composição desta população, além de fornecer subsídios para auxiliar ações na área de saúde para melhor atender as necessidades desta população / The Brazilian population is one of the most heterogenic of the world due to miscegenation between three main ethnical groups (Amerindians, Europeans and Africans) that make up this population. However the distribution of these three groups through the Brazilian territory was not homogeneous so that the ratios of Africans, Amerindians and Europeans differ according to the geographic regions. In Bahia, the African descendants ratio is 77,5% according to the self-denomination of IBGE census. Few studies describe the genetic diversity in Bahia and they are mostly based on classic “genetics markers”. Nowadays racial mix and genetic diversity have been estimated by molecular markers known as Population Specific Alleles (PSA) whose frequency varies more than 30% between distinct geographic regions and distinct ethnical populations. Besides PSA, cultural markers are also used like family surnames that are very useful to study the origin and racial mix in miscegenated populations. Data of the literature show that some ethnical groups are at risk for some diseases such as heart and infectious diseases like AIDS. In Brazil, until the end of 2004, the number of individuals infected by HIV-1 was determined by complex interactions among virus features and the host factors. To estimate the contribution of ancestral groups in this population, 10 PSA (AT3-I/D, APO, SB19.3, PV92, FYnull, LPL, CKMM, GC-F, GC-S and CYP3A4) and 2 markers of susceptibility to HIV-1 (CCR5-Δ32 e CCR2-64I) were analyzed in 517 individuals of Bahia infected by HIV-1. . The social-economic conditions were analyzed as well as the ethnicity of those patients through self-determination and phenotypic analyze based on physical features. Besides, their surnames were also analyzed for religious connotation. The estimate of genomic ancestry showed that in this population the African contribution is more important (48%), followed by the European (35%) and Amerindian (17%) contributions. The respective ratios were similar to those of the HIV-1 negative population of Salvador. The phenotypic analyses matched with the results of self-determination except in the case of the blacks. A high frequency of religious- conotated surnames is associated with “black” phenotype, indicating that the analyze of surnames is an important tool for inference of African ancestry. The social-economic analyses showed that low educated populations and low familiar income have more African ancestry suggesting that the ancestry is related to higher susceptibility to HIV/AIDS. So, this study was really important to estimate the ratio of mixture among ancestral groups in the composition of this population. Moreover it provides information that will help to better take care of the health of this population.

nÃo hà / IntroduÃÃo. A intolerÃncia à lactose à uma sÃndrome clÃnica composta por um ou mais cortejos sintomatolÃgicos associados à ingestÃo de lÃcteos (fenÃtipo clÃnico intolerante) e tolerÃncia à lactose na ausÃncia desses sintomas (fenÃtipo clÃnico tolerante). Assim, na prÃtica clÃnica, deve-se estar atento aos casos semelhantes a essa sintomatologia disabsortiva, pois as convergÃncias e diferenÃas entre esses distÃrbios sÃo tÃnues e os diagnÃsticos muitas vezes sÃo imprecisos, tornando o tratamento e a conduta insatisfatÃrios. Portanto, sÃo necessÃrios estudos que utilizem diferentes mÃtodos diagnÃsticos, assim como comparar os diferentes mÃtodos utilizados na prÃtica clÃnica e averiguar o mais apropriado para dar o diagnÃstico conclusivo, uma vez que nem sempre à fÃcil, haja vista que os sintomas sugerem outras doenÃas. Objetivo. Avaliar as caracterÃsticas fenotÃpicas, a resposta ao teste quÃmico de tolerÃncia à lactose e genÃtipo de pacientes com hipÃtese diagnÃstica de intolerÃncia à lactose e a correlaÃÃo entre eles. Material e mÃtodos. Foi realizado um estudo transversal no Hospital UniversitÃrio Walter CantÃdio (HUWC), com 173 pacientes que apresentavam fenÃtipo positivo e foram atendidos no serviÃo do ambulatÃrio dos servidores do HUWC, no perÃodo de janeiro a agosto de 2010. A amostra final foi composta por 119 pacientes que realizaram o teste de tolerÃncia à lactose e genotipagem do gene da florizina-lactase hidrolase (LPH). Resultados. Dentre os participantes, a maioria era: do sexo feminino, 54,6% (65 casos); da faixa etÃria de 46-55 anos, 26,5% (32 casos); casada, 65,6% (78 casos); de cor parda, 53,8% (65 casos); de nÃvel superior, 42,9% (51 casos). A prevalÃncia de intolerÃncia à lactose foi de 45,4% e a de intolerÃncia quÃmica foi de 73,9%. Os sintomas investigados que apresentaram maior prevalÃncia no intolerante à lactose foram: flatulÃncia, 81,4% (44 casos); empachamento, 68,5% (37casos); borborigmo, 59,3% (32 casos); e diarreia, 46,3% (25 casos). A presenÃa dospolimorfismos C>T-13910 e polimorfismos G>A-22018 no gene da LPH foi identificada nos indivÃduos autorreferidos como intolerantes à lactose, sendo, portanto, um excelente exame para o diagnÃstico. O diagnÃstico de intolerÃncia à lactose que mais se apresentou adequado foi a diferenÃa basal <15 com a curva de ROC maior que 80,3%, com boa sensibilidade e especificidade. ConclusÃes. Observa-se uma correlaÃÃo genotÃpica e quÃmica entre os indivÃduos intolerantes, sugerindo que o teste molecular poderia ser proposto para o diagnÃstico laboratorial de intolerÃncia à lactose, e, no teste quÃmico, a diferenÃa basal <15 foi a mais adequada. / Introduction. Intolerance to lactose is a clinical syndrome comprising one or more corteges symptomatology associated with the ingestion of milk (clinical phenotype intolerant) and lactose tolerance in the absence of symptoms (clinical phenotype tolerant). Thus, in practice, must be attentive to cases similar to these badly absorptive symptoms because the convergences and differences between these disorders are tenuous and diagnoses are often inaccurate, making treatment and unsatisfactory conduct. Therefore, studies are needed using different diagnostic methods, and compare the different methods used in clinical practice and determine the most appropriate to give a conclusive diagnosis, since it is not always easy, given that the symptoms suggest other diseases. Objective.To evaluate the phenotypic characteristics, the response to chemical test for lactose tolerance and the genotype of patients with diagnostic hypothesis of intolerance to lactose and the correlation between them.Material and methods. We conducted a cross-sectional study at the University Hospital Walter Cantidio (HUWC), with 173 patients who had positive phenotype and were seen at the outpatient service of servers HUWC, from January to August 2010. The final sample consisted of 119 patients who underwent the lactose tolerance test and genotyping of the gene for lactase-phlorizin hydrolase (LPH). Results. Among the participants, most were: female, 54.6% (65 cases), the age group of 46-55 years old, 26.5% (32 cases); married, 65.6% (78 cases); dun-colored, 53.8% (65 cases); higher level, 42.9% (51 cases). The prevalence of intolerance to lactose was 45.4% and chemical intolerance was 73.9%. Symptoms investigated more prevalent in lactose intolerant were flatulence 81.4% (44 cases); bloating, 68.5% (37casos); borborygmus, 59.3% (32 cases) and diarrhea, 46, 3% (25 cases). The presence of the polymorphisms C> T polymorphisms and 13 910-G> A-22018 in LPH gene was identified in individuals selfreferred as lactose intolerant, and is therefore an excellent test for the diagnosis. The diagnosis of lactose intolerance that most had adequate baseline the difference was <15 with ROC curve greater than 80.3%, with good sensitivity and specificity. Conclusions. There is a correlation between genotype and chemical intolerant individuals, suggesting that the molecular test could be proposed for the laboratory diagnosis of lactose intolerance, and the chemical test, the difference basal <15 was more appropriate.

Orientador: Luis Alberto Magna / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-09T09:27:48Z (GMT). No. of bitstreams: 1 Braganca_WelbeOliveira_D.pdf: 5203003 bytes, checksum: 128dd161edb4a5ee7d5a3d88e01d1f47 (MD5) Previous issue date: 2007 / Resumo: A detecção do polimorfismo do DNA analisando microssatélites (STR - Short Tandem Repeats) ou minissatélites (VNTR - Variable Numbers of Tandem Repeats) pelas técnicas de PCR (Polymerase Chain Reaction) ou RFLP (Restriction Fragment Lenght Polymorphism) causou um grande impacto e revolucionou a ciência forense. Hoje se pode, com grande precisão, excluir um indivíduo de ser falsamente acusado de uma paternidade ou de um crime. Quando um suspeito não pode ser excluído de ser o pai ou o doador da amostra criminal, o próximo passo é calcular a probabilidade de se observar um outro genótipo igual ao do acusado. Para que isso seja possível selecionam-se aleatoriamente indivíduos na população, avalia-se a raridade do perfil genotípico desta população determinando-se a freqüência de cada alelo encontrado e estima-se a singularidade do DNA do suspeito pela comparação com esta freqüência. Todas estas informações são obtidas a partir de um banco de dados com a mencionada freqüência alélica. No Brasil, atualmente, quando se realiza um exame de investigação de paternidade ou criminalística utilizando-se a análise de VNTR, utiliza-se o banco de dados da população estadunidense contendo o perfil genotípico para esses loci. Para se chegar a uma precisão fidedigna no resultado dos exames seria necessária a utilização de um banco de dados brasileiro, objetivo inicial deste trabalho, o qual deverá ser uma importante ferramenta para a crescente demanda científica e forense no Brasil. Este trabalho descreve o perfil genotípico da população do sudeste do Brasil, gerado por RFLP dos loci de VNTR D1S7, D2S44, D4S139, D5S110, D6S132, D7S467, D8S358, D10S28, D17S26 e D17S79. Os dados populacionais foram obtidos pela digestão enzimática do DNA genômico com HaeIII seguida de eletroforese em gel de agarose e detecção por quimiluminescência. Uma amostra de 351 indivíduos representando a população da região sudeste brasileira foi selecionada nos estados de Minas Gerais, São Paulo e Espírito Santo (Brasil). As freqüências dos alelos estudados foram determinadas a partir desta amostra. Os loci descritos se encontraram em equilíbrio de Hardy-Weinberg. Os dados obtidos foram comparados com o banco de dados de freqüências destes alelos previamente descritos para a população não negróide do Estado do Rio de Janeiro, Brasil, detectando-se a não semelhança entre as amostras. Foi feita a comparação com o banco de dados de freqüências alélicas de ¿Caucasian¿,¿African american¿,¿Chinese¿,¿SE Hispanics¿ e ¿SW Hispanics¿ dos EUA não se encontrando semelhança entre as amostras. As freqüências alélicas obtidas neste estudo podem ser usadas em análises forenses e investigação de paternidade bem como uma estimativa de freqüência alélica de minissatélites da população brasileira. O banco de dados alélicos, assim constituído, trará a precisão real requerida nas análises forenses e investigações de paternidade, ao contrário das análises que utilizam como referência bancos de dados de populações dos EUA / Abstract: The frequency of the VNTR loci D1S7, D2S44, D4S139, D5S110, D6S132, D7S467, D8S358, D10S28, D17S26 e D17S79 were determined in a sample that contained subjects from the states of São Paulo, Minas Gerais and Espírito Santo, Southwest region of Brazil. The data were generated through the digestion of the genomic DNA with HaeIII followed by the analysis by RFLP and chemiluminescent detection. All the loci described meet Hardy-Weinberg expectations. The data obtained were compared with the frequency Database of these alleles previously described for the non-black of the State of Rio de Janeiro, Brazil, and it was detected that there was no match among the samples. It was also made a comparison with the database of allelic frequencies of ¿Caucasian¿, ¿African American¿, ¿Chinese¿, ¿SE Hispanics¿ e ¿SW Hispanics¿ from the USA and no match was found. In conclusion, this work reports a database of distribution of allelic frequencies of VNTR loci for the population of the southwest of Brazil. The frequency data presented might be used in forensic analyses and in paternity investigation in the population of the southwest of Brazil as well as in other populations of Brazil. It was also showed the difference found when selecting the population by races and not by geographic distribution, as well as the importance of the creation of a database of allelic frequencies separated for the different populations. The allelic database, built hereby, will bring the exact required precision in the forensic analyses and paternity inquiries, in contrast with the analyses that use as reference databases from U.S.A. population / Doutorado / Ciencias Biomedicas / Doutor em Ciências Médicas

We propose an experimental model suitable for demonstrating allele frequency change in Drosophila melanogaster populations caused by selection against an easily scorable conditional lethal, namely recessive flightless alleles such as apterous and vestigial. Homozygotes for these alleles are excluded from reproduction because the food source used to establish each generation is accessible only by flight. The observed dynamics of flightless-allele frequencies generally follows the theoretically predicted pattern, with slight deviation toward less intense selection. We also suggest observing selection against flightindependent visible marker alleles in the same population as a meaningful comparison. The proposed experiments can easily be scheduled within one semester, and the expected data provide ample opportunities for discussion of quantitative evolutionary patterns.

This study describes the development and validation of mutagenized cloned DNA constructs, which correspond to the polymorphic regions of the class II region of the HLA complex. The constructs were used to verify the allelic specificity of primers and probes in polymerase chain reaction (PCR)-based HLA typing assays such as Sequence Specific Primers (SSP) and Sequence Specific Oligonucleotide Probes (SSOP). The constructs consisted of the entire polymorphic region of exon 2 of class II HLA allele sequences that included primer annealing sites or probe hybridization sites. An HLA allele sequence was inserted into a plasmid, cloned, then mutagenized to match a specific HLA allele, and finally, the correct clone was verified by bidirectional sequencing of the insert. Thus, the construct created a cloned reference DNA sample for any specific allele, and can be used to validate the accuracy of various molecular methodologies.

The relatively low cost of Next-Generation Sequencing (NGS) has enabled researchers to generate large amounts of sequencing data in order to identify disease-causing mutations and to assemble simple genomes. However, NGS has inherent limitations due to the short DNA read lengths and high error rate associated with the technique. The short read lengths of NGS prevent the assembly of genomes with long stretches of repetitive DNA, and the high error rate prevents the accurate detection of rare mutations in heterogeneous populations such as tumors and microbiomes. I have co-developed new NGS methods to overcome these challenges. In order to increase the effective read length of NGS reads, local de novo assembly of short reads into long contigs can be achieved through the use of Paired-End Restriction-site Associated DNA Sequencing (RAD-PE-Seq). With the RAD-PE method, I sequenced a stickleback fosmid and generated contigs with an N50 length of 480 nucleotides. In order to eliminate false-positive mutations caused by the high error rate of NGS, the Paired-End Low Error Sequencing (PELE-Seq) method was developed, which uses numerous quality control measures during the sequencing library preparation and data analysis steps in order to effectively eliminate sequencing errors. Control testing of the PELE-Seq demonstrates that the method completely eliminates false-positive mutations at sequencing read depths below 20,000X coverage, compared to a ~20% false-positive rate obtained with previous methods. The high accuracy of the PELE-Seq method allows for the detection of ultra-rare mutations in a genome, which was previously impossible with NGS. This dissertation includes previously published and unpublished co-authored material.

Chan Wing Yan Michael. / "August 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 168-200). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

The major histocompatibility complex (MHC) is one of the most variable regions in the vertebrate genome. Many genes within the MHC play important roles in the development of an immune response, including the response to pathogens, by presenting pathogen fragments to T cells. Pathogen-mediated balancing selection is thought to be important in maintaining the high levels of allelic variation at these loci, though the precise mechanism remains unclear. The number of studies of MHC diversity in non-model organisms has increased dramatically in recent years as genotype data have become cheaper and easier to generate; however, key limitations in many such studies remain a lack of high quality MHC genotypes and associated phenotype data. Many studies focus on a single MHC locus, assuming that one locus will represent the full range of variation within each MHC haplotype. Alternatively, the products of different loci may co-amplify, preventing locus-specific genotypes and hence heterozygosity being accurately determined. Non-model systems are also often limited by small sample sizes and limited recording of associated host and pathogen measures, which, combined with high levels of allelic variation at MHC loci, can limit statistical power. Finally, few MHC studies control for the general effect of relatedness in explaining host traits before testing for MHC effects. With so many methodological impediments, it is challenging to identify robust associations between MHC variation and host phenotypes, such as parasite burden or fitness, and to draw conclusions about the mechanisms underpinning the maintenance of diversity at MHC loci. In this thesis, I address these problems by developing a SNP-based haplotyping system for a population of unmanaged Soay sheep (Ovis aries) on Hirta, St. Kilda, for which data is available on pedigree, phenotypic traits and fitness and its components over a 30- year study period. The ovine MHC consists of four classes of loci, within which loci are tightly clustered and show reduced recombination rates compared to the genome average. Although the mammalian MHC is usually highly variable, one would expect that the number of haplotypes within an MHC class in an island population of sheep with no immigration to be limited. The class IIa region of the ovine MHC includes the classical class II loci which are typically thought to be involved in the presentation of peptides derived from extracellular pathogens, including gastrointestinal helminths, in sheep and other mammals. In chapters 2 to 4, I describe the characterisation of class IIa haplotypic diversity in the Soay sheep using direct Sanger sequencing of PCR amplified fragments, which, in combination with cloning, revealed eight distinct haplotypes. With this knowledge of haplotypic diversity, and genotypes for a sample of Soay sheep typed on the Ovine Infinium HD chip (approximately 600K SNPs), I developed a panel of 13 SNPs which could be used to impute the class IIa haplotypes. This panel was genotyped by KASP (Kompetitive Allele Specific PCR) in 6034 samples and used to impute the class IIa haplotypes. After quality control measures, class IIa haplotypes were successfully imputed for 5349 individuals. Evidence of balancing selection was identified using the Ewens-Watterson test at different life history stages and within the standing population each year between 1985 and 2012, showing that allele frequencies were more even than would be expected under neutrality. However, there was no evidence of deviation from Hardy-Weinberg equilibrium identified at different life stages or in the standing population in any year. In chapter 5, I investigate associations between the MHC class IIa haplotypes and individual-level data on host phenotypes - body weight, plasma immunoglobulin levels (measured as anti-Teladorsagia circumcincta third larval stage IgA, IgE and IgG) and strongyle faecal egg counts (FEC). Associations were tested within mixed effects models which were used to account for repeated measures and control for fixed effects known to affect the response variables, as well as within an animal model framework to account for relatedness between individuals. Haplotype heterozygosity was unrelated to any of the traits investigated, suggesting a general heterozygote advantage is unlikely to be operating within the Soay sheep. Six of the eight class IIa haplotypes were associated with multiple traits in different age-sex classes, although many of these associations were removed after inclusion within animal models. The evidence of balancing selection and associations between class IIa haplotypes and phenotypes related to health offers a promising glimpse into the evolutionary mechanisms which may be operating to maintain diversity within this region.

Submitted by Fabíola Silva (fabiola.silva@famerp.br) on 2017-09-29T18:21:41Z No. of bitstreams: 1 camilaravazzigauch_dissert.pdf: 1221932 bytes, checksum: 8184414238eac76d3bb5fced2b86cc83 (MD5) / Made available in DSpace on 2017-09-29T18:21:41Z (GMT). No. of bitstreams: 1 camilaravazzigauch_dissert.pdf: 1221932 bytes, checksum: 8184414238eac76d3bb5fced2b86cc83 (MD5) Previous issue date: 2015-12-03 / Introduction: The HLA (Human Leukocyte Antigen) molecules are proteins encoded by genes highly polymorphic and are involved in the immune response process. Polymorphisms of HLA genes differ between populations, both in frequency and in the presence or absence of specific alleles and haplotypes. Considering that the distribution of organs for transplant depends on HLA matching between donor and recipient, the knowledge and determination of the HLA polymorphism are of great importance in the process of allocation of organs for transplantation. Moreover, the knowledge of the HLA diversity is an important tool for studies of the origin of populations. Objectives: This study aimed to characterize the allele and haplotype frequencies of HLA-A, -B, and -DRB1 in a cohort of renal transplant candidates populations in the region of São José do Rio Preto (State of São Paulo), to compare the allele frequencies between Caucasian and Black in that region, as well as to compare these frequencies with different Brazilian populations reported. Materials and Methods: The HLA-A, -B, and -DRB1 allele and haplotypes frequencies were analyzed in a sample of 2.624 individuals and classified according to the ethnic group (2.347 Caucasians and 277 Blacks). The HLA class I (A, B) and class II (DRB1) specificities were determined by Complement-Dependent Microlymphocytotoxic (CDC) and Polymerase Chain Reaction/Sequence Specific Priming (PCR-SSP) methods, respectively. Results: All loci studied were in Hardy–Weinberg Equilibrium (p>0.05). Twenty-one HLA-A, 34 HLA-B and 13 HLA-DRB1 allelic groups were identified. The most frequent alleles for each locus were HLA-A*02, HLA-B*35, and HLA-DRB1*11. The most frequent haplotypes found were A*01 B*08 DRB1*03 among Caucasians and A*29 B*44 DRB1*07 among Blacks. Conclusions: The most common alleles for each locus among the renal transplant candidates were A*02, B*35 and DRB1*11. The most common haplotype was A*01 B*08 DRB1*03. The same haplotype was the most frequent in Caucasoid sample while the haplotype A*29 B*44 DRB1*07 was the most common in the Blacks sample. / Introdução: As moléculas HLA (Human Leucocyte Antigens) são proteínas codificadas por genes altamente polimórficos e estão envolvidas no processo de resposta imunológica. Os polimorfismos dos genes HLA diferem entre as populações, tanto na frequência como na presença ou ausência de alelos e haplotipos específicos, Considerando-se que a distribuição de órgãos para transplante depende da compatibilidade HLA entre doador e receptor, o conhecimento e determinação do polimorfismo HLA são de grande importância no processo de alocação de órgãos para transplantes, além de ser uma importante ferramenta em estudos populacionais. Objetivos: 1) Determinar as frequências alélicas para os locus HLA-A, -B e -DRB1 em uma amostra de candidatos a transplante renal no Brasil. 2)Determinar os haplótipos HLA mais freqüentes nessa amostra. 3) Comparar as diferenças de frequências alélicas e haplotípicas entre os grupos de caucasóides e negros da população analisada. Materiais e Métodos: As frequências alélicas e haplotípicas para os locus HLA-A, -B e -DRB1 foram analisadas em uma amostra de 2.624 candidatos a transplante renal e classificadas de acordo com o grupo étnico (2.347 Caucasóides e 277 Negros). As especificidades HLA de classe I (AB) e de classe II (DR) foram determinadas de acordo com a técnica Microlinfocitotóxica Dependente de Complemento (CDC) e Polymerase Chain Reaction - Sequence-specific Primers (PCR-SSP), respectivamente. Resultados: Considerando a amostra total, todos os loci estudados estavam em equilíbrio de Hardy-Weinberg (p>0,05). Foram identificados 21 grupos de alelos para o locus HLA-A, 34 para HLA-B e 13 para HLA-DRB1. Os alelos mais freqüentes para cada locus foram HLA-A*02, HLA-B*35 e HLA-DRB1*11. O haplótipo mais freqüente foi A*01 B*08 DRB1*03 entre a amostra de Caucasóides e A*29 B*44 DRB1*07 entre a amostra de Negros. Conclusões: Os alelos HLA mais freqüentes na população de candidatos a transplante renal foram HLA-A*02, HLA-B*35 e HLA-DRB*11. O haplótipo mais comum foi A*01 B*08 DRB1*03. Esse mesmo haplótipo foi o mais frequente na amostra de Caucasóide da população analisada enquanto que, A*29 B*44 DRB1*07 foi o mais comum na amostra de Negros.

This project investigated the genetic composition of natural populations of Anadara trapezia in Australia at three spatial scales : i) microgeographic (within an estuary, 50 metres to ~ 6 kilometres); ii) microgeographic (within populations, less than 50 metres); and, iii) macrogeographic (hundreds of kilometres along the coast of Australia). Allozyme polymorphism surveys using cellulose acetate strips have revealed, from 43 enzymes screened, 18 putative polymorphic loci. Comparisons of levels of heterozygosity among enzyme structural groups showed no significant differences, however, monomers were significantly more variable as a group than multimers. Significant differences in the level and distribution of polymorphism among functional groups of enzymes were observed. It appears that selection may be acting at the molecular level, not only on a particular locus, but on a group of functionally similar loci. At the macrogeographic scale, significant departures from random mating were observed in most populations. Significant differences in allele distribution among populations of A. trapezia along the east coast of Australia were found. At the macrogeographic scale, heterogeneity of allele frequencies may depend upon the distance separating the populations and surface water currents. Differentiation among population groups in this study is attributed to changes in the direction of the East Australian Current combined with onshore countercurrents. The systematic status of the disjunct western Australian population of A. trapezia was also evaluated as compared with the east coast populations. No evidence of genetic, hence evolutionary divergence was found. The results have serious implications in the management of fisheries as erroneous assumptions in fisheries management models may lead to depletion and near extinction of marine species. The research stresses the necessity of sampling at multiple scales and replication strategies. It also highlighted the complexities researchers are faced with in studies of marine bivalves, such as the presence of null alleles, deficiencies of heterozygotes, apparent inbreeding and the small geographic scales governing population structure. / Doctor of Philosophy (PhD)