Cross-Platform Application of DNA Methylation Age Estimation Model in Eastern Chinese Han Population / 法医学杂志

OBJECTIVES@#To evaluate the forensic application value of an age estimation model based on DNA methylation in eastern Chinese Han population, and to provide a theoretical basis for exploring age estimation models suitable for different detection platforms.@*METHODS@#According to the 6 age-related methylation sites in the published blood DNA methylation age estimation models of Chinese Han population, the DNA methylation level of 48 samples was detected by pyrosequencing and next-generation sequencing (NGS). After submitting DNA methylation levels to the age estimation model, the DNA methylation ages were predicted and compared with their real ages.@*RESULTS@#The 6 DNA methylation sites in both detection techniques were age-related, with an R2 of 0.85 and a median absolute deviation (MAD) of 4.81 years when using pyrosequencing；with an R2 of 0.84 and MAD of 4.41 years when using NGS.@*CONCLUSIONS@#The blood DNA methylation age estimation model can be used under pyrosequencing and multi-purpose regional methylation enrichment sequencing technology based on NGS and it can accurately estimate the age.

Establishment of DNA Genetic Marker Identification System for Plant Evidence / 法医学杂志

Objective To establish a species identification system based on DNA genetic markers for plant evidence. Methods Two hundred common plants in Shanghai were collected and identified by mor-phological characteristics. The primers of gene segments rbcL, matK, and ITS were designed and amplified. The PCR amplicon was detected by agarose gel electrophoresis. After the sequencing, the universality and the identification capacity of the three markers were evaluated. Results The success rate of amplifi-cation was in order of rbcL (99.5％) >matK (92.5％) > ITS (86.0％). The identification capacity of the combination of rbcL and matK was better than that of rbcL or matK, by which most plant species could be identified to the genus or higher. ITS was not suitable to be a unique marker because of its unstable result, but it still could be a powerful supplement. The identification capacity of the combination of rbcL, matK and ITS was higher than that of rbcL and matK, by which most plant species could be identified to the genus or lower. Conclusion The identification system with the combination of rbcL, matK and ITS as markers has excellent universality for plant evidence, which can distinguish most plant species to the genus or lower.

A utilização de técnicas de biologia molecular na genética forense: uma revisão / The use of molecular biology techniques in foresinc genetics: a review

Os avanços nas tecnologias de DNA surtiram um enorme impacto no campo da ciência forense. Com uma incrível sensibilidade e um alto poder de discriminação, a análise de DNA tem sido uma poderosa ferramenta para a identificação humana e investigaçõescriminais. O presente estudo fará uma revisão sobre as técnicas de Biologia Molecular mais significativas – RFLP, VNTR, PCR e STR – que foram desenvolvidas nas últimas décadas, tendo como princípio o estudo de diferentes polimorfismos de DNA para a identificação precisa de indivíduos. Por um longo tempo, estes polimorfismos foram detectados por técnicas que possuíam como base a eletroforese.Outra técnica que também será exposta, Southern Blotting, visa a identificação de uma seqüência de bases específicas do DNA, que foi por muito tempo aplicada tanto na detecção de SNPs como de VNTRs e STRs. Além disto, será descrita a reação em cadeia da polimerase (PCR), um método laboratorial capaz de copiar milhões de vezes um segmento do DNA, que se destaca perante outras técnicas por ser um procedimento relativamente simples e fácil de realizar em laboratório, gerando resultados precisos e satisfatórios, em um curto espaço de tempo. Por fim, serão descritos os métodos automatizados que, a partir de PCR, permitem a detecçãorápida de marcadores moleculares, a fim de facilitar e tornar mais precisa a identificação forense.

The advent of DNA-based technologies promoted significant impact in the field of forensic science. According to its highsensibility and powerful discrimination, the DNA analyses have been a powerful tool to human identification and criminal investigations. The present study will be taken to produce a review about the most important techniques of molecular biology developed in recent decades, such as RFLP, VNTR, PCR and STR. These techniques are based in the study of different polymorphisms in the DNAand it could be used in the precise subjects identification. For a period, these polymorphisms were detected through techniques based in electrophoresis. Besides, other procedures will be explained, like Southern Blotting that aims to identify specific DNA sequences and could be applied in the research of SNPs, VNTRs and STRs. It will be also described the Polimerase Chain Reaction (PCR), alaboratorial method able to amplify millions of a short DNA segment. This technique has some advantages through the others because it is a simple and easy procedure to be done in laboratories, and could offer accurate and satisfactory results in a short period of time. Concluding, automated techniques based in PCR will be present that permit fast detection of molecular evidences in order to facilitate and promote reliable forensic identification.