Population genetics of nine short tandem repeat loci: allele frequency distribution in a Brazilian population sample

Gene and genotype frequencies in relation to the D3S1358, vWA, FGA, TH01, TPOX, CSF1PO, D5S818, D13S317, and D7S820 loci were determined in a sample of 290 unrelated individuals (204 Caucasians and 86 mulattoes) living in the city of S?o Paulo, Brazil. The sex test Amelogenin was also performed in all subjects from our sample, revealing the expected sex in all instances. Allele frequency data obtained from the analysis of these samples were in the usual range of other population groups with similar racial background. In the sample of Caucasian individuals, panmictic proportions were ruled out in relation to TPOX and CSF1PO loci, but only in the latter was the overall frequency of heterozygotes significantly less than expected. In the sample of mulattoes, Hardy-Weinberg proportions were rejected in relation to FGA and CSF1PO loci, but in no instance were the overall numbers of heterozygotes different from the corresponding expected ones under panmixia. Taking into account all this and also the number of tests performed, the degree of genetic heterogeneity of Brazilian populations, and the critical level reached by the significant results (1% < alpha<5%), the departures from panmixia here observed can be considered to be negligible in altering significantly biologic relationship odds calculated under the assumption of random matings.     

Y-STRs in forensic medicine: DNA analysis in semen samples of azoospermic individuals

ABSTRACT: The incidence of rape has increased, especially in metropolitan areas, such as the city of São Paulo. In Brazil, studies about it have shown that the majority of this type of crime is committed by the relatives and persons close to the victim. This has made the crime more difficult to be denounced, as only 10% of the cases are reported to competent police authorities. Usually, cytological exams are carried out in sex crime investigations. The difficulty in showing the presence of spermatozoa is frequent, but it does not exclude the presence of male DNA. The absence of spermatozoa in material collected from rape victims can be due to several factors, including the fact that the agressor suffers from azoospermia. This condition can be the result of a successful vasectomy. As the majority of DNA in the ejaculation sample is from spermatozoa, there is much less DNA to be analyzed. This study presents the application of Y‐STRs (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, and DYS393) in DNA analysis of sperm samples from 105 vasectomized men. The study demonstrated a great variation in DNA concentration. DNA extraction and amplification was possible in all sperm samples even in the absence of spermatozoa. The same profile was observed, for each individual, from DNA extracted from blood, pre‐ and postvasectomy semen samples. The use of markers specific for Y chromosome in sex crime cases, especially in the absence of spermatozoa, is very important, mainly because in most situations there is a small quantity of the agressor's DNA in the medium and a large quantity of the victim's DNA.     

Analysis of DNA profiles extracted from degraded samples from archival of formalin fixed tissue included in paraffin (FFTIP) and hairs

The possibility of studying DNA extracted from archival of formalin fixed tissue included in paraffin (FFTIP) enables valuable retrospective investigations. However, according to some authors it is difficult to obtain genomic DNA of good quality, since the process of fixation often results in fragmentation of DNA. In order to evaluate the quality and quantity of DNA extracted, necropsy samples of FFTIP (spleen/lung) and hairs, with or without bulbs, were analyzed using three methods of extraction (QIAamp DNA mini, QIAamp DNA micro-kit and phenol–chloroform followed by microcon YM-30). The amount of DNA recovered was quantified by spectrophotometer. The β-actin, amelogenin gene and the profiles of STR were analyzed. Based on experimental results, a general guideline concerning the appropriate extraction method according to the tissue and the quantity of the starting material for the analysis of DNA from FFTIP and hairs could be suggested.     

A qualitative study of compact bone microstructure and nuclear short tandem repeat obtained from femur of human remains found on the ground and exhumed 3 years after death

Forensic identification of human remains is composed of anthropological study of race, sex, age, etc. By using these traditional methods, inconclusive or nonidentified cases could be subjected to DNA analysis. However, in spite of advances in human identification techniques, especially by PCR-amplified DNA, some limitations that affect the ability of obtaining DNA from human remains still persist. Light microscope sections of postmortem compact bones from human remains are presented here for the purpose of increasing a forensic examiner's prediction of successful nuclear DNA typing. Femoral compact bones were obtained from 7 human remains found on the ground, in different degrees of decomposition, and were cleaned by boiling to remove soft tissues, 8 collections of bones having undergone natural decomposition, not boiled (as no soft tissue was adhered), and 5 cadavers 12 to 16 hours postmortem. The histologic sections were stained by hematoxylin and eosin, the loci CSF1PO, TPOX, TH01, F13A01, FESFPS, vWA, D16S539, D7S820, D13S317, and amelogenin were amplified by PCR, and the polyacrylamide gel was stained with silver. The results presented here clarify questions concerning the viability of DNA for identification analysis, and they also may help to establish better strategies for optimization of DNA extraction and analysis in compact bones of human remains.     

Potential definition of the time of death from autolytic myocardial cells: a morphometric study

Morphometric methods and transmission electron microscopy were used to quantify modifications occurring in the mitochondria of dog myocardium during the first four hours of autolysis. Myocardial fragments were obtained from the outer free wall of the left ventricle, during anesthesia (control-zero) and at 15, 45, 120, and 240 min after cardiac arrest, maintaining the heart "in situ" at 22 degrees C. During the 240 min of autolysis, the main parameters evaluated showed: (a) a decrease in the number of mitochondria from 0.31 to 0.12 per micron 3 of cytoplasm. The decrease over the first 45 min reached 50% of the initial value; (b) an increase in mitochondrial volume, three times greater after the first 45 min (from 0.92 to 2.68 micron 3) and four times greater after 240 min (from 0.92 to 3.79 micron 3); (c) an increase in mitochondrial outer membrane surface area from 5.51 to 12.54 micron 2; (d) an increase in the surface area of individual mitochondria inner membrane and cristae from 27.60 to 56.96 micron 2. The progressive nature of the alterations and the difference in the numerically expressed values allow correlation with the time of somatic death. The authors emphasize the need for further studies in order to complement the present study.     

Analysis of DNA in minute volumes of blood from stains and crusts

As the first step, the locus D1S80 was amplified by the polymerase chain reaction technique from genomic DNA extracted from artificial bloodstains and crusts with different amount of blood (32 microl, 16 microl, 8 microl, 4 microl, 2 microl, and 1 microl). In all samples of bloodstains and crusts, identification by DNA analysis was possible. As the second step, the locus HLA-DQA1 was amplified from genomic DNA extracted from diluted blood samples (640, 320, 160, 80, 40, 20, 10, and 5 leukocytes). DNA amplification was possible in diluted blood samples with at least 10 leukocytes. Considering the conditions in which the present study was carried out, it was possible to conclude that 1 microl of bloodstains or crusts was enough for identification. It was also concluded that five leukocytes are not enough material to render consistent DNA identification.     

Government survival in semi‐presidential regimes

As semi‐presidentialism has become increasingly common in European democracies, so have the debates about the consequences of several of its political and institutional features. In particular, in those regimes, cohabitation between presidents and cabinets of different parties and cabinet dismissal powers on the part of presidents are thought to be a source of inter‐branch conflict and government instability. However, so far, most empirical work on government survival has failed to confirm any of these expectations. This article addresses this disjuncture between theory and empirical results by making a twofold contribution. First, it takes into account the internal diversity within semi‐presidentialism, modeling the implications for government survival of different configurations between presidential powers’ of cabinet dismissal, parliament dissolution and cohabitation in European semi‐presidential systems. Second, it reconsiders traditional government survival using the competing risks framework by adding a distinction between two different types of non‐electoral replacement: those where replacements imply a change in the party of the prime minister and those where they do not. Once such an approach is adopted, that presidential powers of parliamentary dissolution and cabinet dismissal indeed emerge as highly relevant for explaining government survival in these regimes.     

Allele and genotype frequencies for D1S80 locus in a Brazilian population sample

Gene and genotype frequencies in relation to the D1S80 locus were determined in a sample of 197 unrelated individuals (144 Caucasians and 53 Mulattoes), living in the city of S?o Paulo, Brazil. The Mulatto group was composed by mixed individuals who presented at least one negroid physical characteristic or declared themselves to be of mixed (Black-White) ancestry. Nineteen different alleles were detected in the Caucasian sample and 15 among Mulattoes. Alleles 18 and 24 were found to be the most common ones in the Caucasian population with frequencies of 0.173 and 0.357 respectively; the sample heterozygote frequency was estimated in 0.824. Alleles 18, 24, and 28 were found to be the most common alleles among Mulattoes with respective frequencies of 0.150, 0.349, and 0.113; the sample heterozygote frequency was 0.759. Fifty-five different genotypes were detected among Brazilian Caucasians whereas the respective figure among Mulattoes was 31. No significant deviations from Hardy-Weinberg equilibrium were found in both population samples.     

Parentage testing on blood crusts from firearms projectiles by DNA typing settles and insurance fraud case

We describe a case of a fraudulent insurance claim. The family of an adult white male (DLF) notified the police of their son's disappearance. After a few weeks, a corpse that presented characteristics similar to those of the DLF was found in advanced stages of decay and was identified by the family as being DLF. The family then filed a claim for the life insurance that DLF had taken out just before he disappeared. Suspicions were raised about the identification of the corpse, because it had been done only visually, and because the insurance policy had been taken out just prior to DLF's disappearance. The insurance company requested a postmortem examination for identification. As the corpse had been cremated immediately after identification by the family, the biological material that was encrusted on the two projectiles removed from the body was used for analysis. The blood crusts provided enough genomic DNA for us to carry out PCR base typing of HLA-DQA1, D1S80, HUMCSF1PO, HUMTPOX, HUMTH01, D3S1744, D12S1090, D18S849, and amelogenin. Results from all loci typing from the corpse presumed to be that of DLF were then compared with that of his alleged biological parents, revealing genetic incompatibility.