Using nuclei isolated from less than 0.2 g tissue or 107 cells, a method is presented for the quantitative determination of amounts of DNA per cell at the picogram level. This technique is based on the enhanced fluorescence of 4′,6-diamidino-2-phenylindole (DAPI) when it binds to DNA. A rapid, one-step nuclear isolation and DNA staining procedure is used to prepare tissue samples for flow cytometric analysis. Frozen tissues give results comparable to those for fresh tissue. Both chicken and trout erythrocyte nuclei were used as reference standards in the determination of amounts of DNA per diploid cell for several mammals and Amazon molly fish. The consistent values obtained for different tissues from the same organism show the accuracy of this method for DNA measurement.

Quantification of human DNA in forensic samples is an important step during STR profiling because the STR genotyping is sensitive to the quantity of DNA used in the PCR reaction. This study focuses on the importance of quantification in the entire process of genetic analysis. Two real time PCR platforms (Roche LightCycler480 System and ABI 7900 RT PCR) were used to compare two commercial kits in terms of DNA quantification. It was found out that accuracy of absolute quantification values in commercial quantification kits is strongly dependent on the construction of calibration curve. Especially low template DNA samples were used to assess whether QuantifilerTM or Plexor® HY System can determinate a minimum quantification value (cut off value) below which STR profiles would consistently fail to be detected. The usage of Plexor® HY System enabled to determine the cut off quantification value more exactly probably due to different molecular background and chemistry used in this kit. Reliability and other issues connected with cut off value are discussed. In order to better understand the relationship between the quantity of DNA and the number of detectable loci series the dilution experiment with standard DNA007 was done. Quantitative and qualitative consequences of input DNA amount in evaluation of...

<p>The field of forensic genetics is growing fast and the development and optimisation of more sensitive, faster and more discriminating forensic DNA analysis methods is highly important. In this thesis, an evaluation of the use of novel DNA technologies and the development of specific applications for use in forensic casework investigations are presented.</p><p>In order to maximise the use of valuable limited DNA samples, a fast and user-friendly Real-time PCR quantification assay, of nuclear and mitochondrial DNA copies, was developed. The system is based on the 5’ exonuclease detection assay and was evaluated and successfully used for quantification of a number of different evidence material types commonly found on crime scenes. Furthermore, a system is described that allows both nuclear DNA quantification and sex determination in limited samples, based on intercalation of the SYBR Green dye to double stranded DNA. </p><p>To enable highly sensitive DNA analysis, Pyrosequencing of short stretches of mitochondrial DNA was developed. The system covers both control region and coding region variation, thus providing increased discrimination power for mitochondrial DNA analysis. Finally, due to the lack of optimal assays for quantification of mitochondrial DNA mixture, an alternative use of the Pyrosequencing system was developed. This assay allows precise ratio quantification of mitochondrial DNA in samples showing contribution from more than one individual.</p><p>In conclusion, the development of optimised forensic DNA analysis methods in this thesis provides several novel quantification assays and increased knowledge of typical DNA amounts in various forensic samples. The new, fast and sensitive mitochondrial DNA Pyrosequencing assay was developed and has the potential for increased discrimination power.</p>

The field of forensic genetics is growing fast and the development and optimisation of more sensitive, faster and more discriminating forensic DNA analysis methods is highly important. In this thesis, an evaluation of the use of novel DNA technologies and the development of specific applications for use in forensic casework investigations are presented. In order to maximise the use of valuable limited DNA samples, a fast and user-friendly Real-time PCR quantification assay, of nuclear and mitochondrial DNA copies, was developed. The system is based on the 5’ exonuclease detection assay and was evaluated and successfully used for quantification of a number of different evidence material types commonly found on crime scenes. Furthermore, a system is described that allows both nuclear DNA quantification and sex determination in limited samples, based on intercalation of the SYBR Green dye to double stranded DNA. To enable highly sensitive DNA analysis, Pyrosequencing of short stretches of mitochondrial DNA was developed. The system covers both control region and coding region variation, thus providing increased discrimination power for mitochondrial DNA analysis. Finally, due to the lack of optimal assays for quantification of mitochondrial DNA mixture, an alternative use of the Pyrosequencing system was developed. This assay allows precise ratio quantification of mitochondrial DNA in samples showing contribution from more than one individual. In conclusion, the development of optimised forensic DNA analysis methods in this thesis provides several novel quantification assays and increased knowledge of typical DNA amounts in various forensic samples. The new, fast and sensitive mitochondrial DNA Pyrosequencing assay was developed and has the potential for increased discrimination power.

Made available in DSpace on 2015-03-26T13:42:10Z (GMT). No. of bitstreams: 1 texto completo.pdf: 575171 bytes, checksum: 3cf08bba8bb6a93eab8dbf41ef32bd01 (MD5) Previous issue date: 2006-02-03 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Capsicum genus is one of the most important members of the Solanaceae family with high economic value. Out of 25 known species, five are extensively cultivated. Capsicum annuum is the most important commercially by its agronomic value as spice. In despite of this importance, the nuclear DNA content of C. annuum is still uncertain with values from the literature ranging from 5.52 to 10.80 pg. In face of the fast development of digital image technologies in cytometry, this study proposes the utilization of these resources to reevaluate the genomic size in C. annuum. The specific objectives were: (i) to determine the reliability parameters for image cytometry analysis by performing tests of equipment stability, linearity and uniformity of nuclei integrated optical density; (ii) to apply that parameters in analysis of erythrocytes nuclei from Gallus domesticus 'Leghorn' (male and female); and (iii) to develop image cytomery methodologies for determination of the nuclear DNA content of pepper (C. annuum L. 'Fortuna Super'). Hen and rooster blood samples were prepared by using the method of smear preparation. The slides were stained with Feulgen reaction and they were used to perform the quality control procedures and integrated optical density measurements. Root tips of C. annuum were fixed, stained with Feulgen reaction and squashed on a microscope slide. Once the parameters of the reliability for performing image cytometry were established, the application of those standardizations in the chicken red blood cells suggested that this technique allows identification of differences in the nuclear DNA content between rooster and hen. Analysis of variance demonstrated that the 4.32% difference obtained was significant and it was attributed to sexual chromosomes heteromorfism. C. annuum analyses allowed the calculation of integrated optical density values, and they were in iccordance with the international standards for DNA image cytometry. The 2C DNA value for C. annuum 'Fortuna Super', using Pisum sativum as the internal standard, was 8.10 pg. This data differs in 2% from the previously obtained by flow cytometry for the same plant population. Besides, the value obtained in this study differs in16% and 28% from those 2C values previously published by image cytometry and in 7% and 32% for flow cytometry. These results include information about C. annuum genome that can be useful in breeding programs, genome sequencing projects and for comparative studies of genome evolution. / Capsicum é um dos gêneros mais importantes economicamente da família Solanaceae. Das 25 espécies descritas, cinco são extensivamente cultivadas. Capsicum annuum é a mais importante comercialmente, pelo seu valor agronômico como especiaria. Apesar da sua importância, valores de conteúdo de DNA conflitantes, que variam de 5,52 a 10,80 pg, têm sido descritos para essa espécie. Diante dos avanços dos equipamentos digitais nas análises de citometria de imagem, o presente trabalho propôs o estabelecimento desses recursos para reavaliar o tamanho do genoma em C. annuum. Os objetivos específicos foram: (i) o estabelecimento de parâmetros de confiabilidade para análises em citometria de imagem, por meio da realização de testes de estabilidade do equipamento, linearidade e uniformidade da densidade óptica integrada dos núcleos; (ii) aplicação dessa calibração em núcleos de eritrócitos de Gallus domesticus Leghorn (macho e fêmea); e (iii) desenvolvimento de metodologias de citometria de imagem para determinação do conteúdo de DNA em pimentão (C. annuum L. Fortuna Super ). Lâminas de esfregaço de sangue de galinha e galo submetidas à reação de Feulgen foram utilizadas nos testes de calibração e para a determinação da densidade óptica integrada. As preparações citogenéticas de pimentão foram feitas pela técnica de esmagamento de meristemas radiculares submetidos à reação de Feulgen. Uma vez estabelecidos os parâmetros de confiabilidade para a realização da citometria de imagem, a aplicação dessas padronizações em análises de núcleos de eritrócitos de ave permitiu identificar diferenças de 4,32% no conteúdo de DNA nuclear entre machos e fêmeas de G. domesticus. Análise de variância demonstrou que a diferença encontrada era significativa, e essa foi atribuída ao heteromorfismo dos cromossomos sexuais. As análises de citometria de imagem em C. annuum permitiram o cálculo da densidade óptica integrada, atendendo aos parâmetros internacionalmente adotados para esse tipo de estudo. O conteúdo de DNA estimado para C. annuum Fortuna Super , utilizando Pisum sativum Ctirad com o padrão interno, foi de 8,10 pg. Esse valor difere em 2% do obtido previamente por citometria de fluxo, utilizando-se material nuclear foliar da mesma população de plantas. Além disso, o valor obtido difere em 16% e 28% dos valores 2C obtidos por citometria de imagem descritos na literatura e em 7% e 32% dos relatados por citometria de fluxo. Esses resultados abrangem informações acerca do genoma dessa espécie, que podem ser úteis em programas de melhoramento e seqüenciamento e em estudos evolutivos.