Damage caused to fibres by vapour cloud explosions

Research on the very specific damage to single textile fibres caused by vapour cloud explosions is presented. Vapour cloud explosion experiments were carried out using a selection of 41 garments differing in colour, fibre composition and textile construction. Fibres subjected to a vapour cloud explosion become wider at the end, often taking the form of a ball, bulb or shovel, while the morphological structure of the remaining part of the fibre remains almost unchanged. The presented results can clearly indicate that an explosion took place at the scene of the crime. The authors would like to be able to provide investigators with specific information on how to link clothes (and thus people) to a specific type of crime.     

Preparation of degraded human DNA under controlled conditions

DNA typing through analysis of short tandem repeats (STRs) and mitochondrial DNA (mtDNA) by means of the polymerase chain reaction (PCR) and sequencing are the common methods for the forensic identification of persons and reconstruction of kinship, especially when skeletal human remains have to be analyzed. Furthermore, samples typically found at crime scenes may be both quantitatively and qualitatively inadequate since they may contain very scarce and often degraded DNA due to exposure to heat, light, humidity, and microorganisms. In order to improve the performance of STR typing technology in those cases where DNA availability is limited, it would be desirable to have a source of degraded DNA with known properties. For this purpose, we have developed a method to prepare artificially degraded DNA under controlled conditions. By treatment of genomic DNA with sonication and DNAse I we have produced DNA fragments within a defined range of lengths. STR typing of this degraded DNA with a commercially available multiplex kit could only produce partial profiles as indicated by the absence of STR alleles with sizes >200 bp. This artificially degraded DNA can be used for the improvement and standardization of STR typing protocols when only highly degraded DNA is available for analysis.     

Bone as a biomarker of acute fluoride toxicity

The use of bone as a biomarker for chronic and acute exposure to fluoride salts has been suggested, but there are no data published about its use to evaluate lethal intoxication. One hundred and sixty rats were divided into eight groups that received a single oral intubation dose from 0 (control) to 90 mg F/kg as NaF. The animals' time of death was recorded and their femurs were removed for fluoride analysis. Acid-soluble fluoride was determined in the whole bone and on the surface (periosteal), using an ion specific electrode. The data showed a statistically significant relationship between fluoride dose and the number of deaths (P<0.0001). A statistically significant relationship was also found between fluoride dose and fluoride concentration ([F]) in either the whole femur (P<0.0017), on the surface (P<0.0001) or for the ratio periosteal [F]/whole [F] (P<0.0001). However, the [F] on the femur surface was more closely correlated with mortality than that in the whole bone, showing statistically significant differences among the lethal doses and control (P<0.05). The data suggest that the ratio [F] periosteal bone/[F] whole bone, is a biomarker for acute fluoride toxicity.     

Results of the GEP-ISFG collaborative study on two Y-STRs tetraplexes: GEPY I (DYS461, GATA C4, DYS437 and DYS438) and GEPY II (DYS460, GATA A10, GATA H4 and DYS439)

A collaborative exercise was carried out by the Spanish and Portuguese ISFG Working Group (GEP-ISFG) in order to evaluate the performance of two Y-chromosome STR PCR tetraplexes, which include the loci DYS461, GATA C4, DYS437 and DYS438 (GEPY I), and DYS460, GATA A10, GATA H4 and DYS439 (GEPY II). The participating laboratories were asked to type three samples for the eight markers, using a specific amplification protocol. In addition, two control samples, with known haplotypes, were provided. The results obtained by the 13 different participating laboratories were identical, except for two laboratories that failed to type correctly the same two samples for GATA C4. By sequence analyses, two different GATA C4 allele structures were found. One control sample (allele 21) and two questioned samples (allele 22, correctly typed by all the laboratories, and allele 25) presented the following repeat structure: (TCTA)4(TGTA)2(TCTA)2(TGTA)2(TCTA)n, but different from the one found for allele 26 in one sample included in this exercise, as well as in the second control sample (allele 23), namely (TCTA)4(TGTA)2(TCTA)2(TGTA)2(TCTA)2(TGTA)2(TCTA)n. The collaborative exercise results proved that both Y-tetraplexes produce good amplification results, with the advantage of being efficiently typed using different separation and detection methodologies. However, since GATA C4 repeat presents a complex structure, with alleles differing in sequence structure, efficient denaturing conditions should be followed in order to avoid typing errors due to sizing problems.     

Genetic profile of the Ecuadorian Mestizo population (Ecuador-South America) by using the Power Plex 16 System Kit

Allele frequency data for the 15 STR systems and Amelogenine were determined in a population sample of healthy Mestizo unrelated individuals. All loci met Hardy-Weinberg expectations and the high discrimination power of combined system showed the forensic efficiency of these genetic markers. There is a lack of information on Ecuadorian population from a genetic point of view and therefore no previous publications on the distribution of STRs on Mestizos is available. Mestizos are descendents of Spanish and Amerindian people, however, significant differences were found between the former and the populations from Spanish peninsula, that have been analyzed for these genetic markers.     

STRs data for the loci D3S1385, vWA,FGA, D8S1179, D21S11, D18S51, D5S818, D13S317 and D7S820 from Córdoba (Argentina)

Allele and genotype frequencies for nine STRs loci included in the AmpFlSTR Profiler Plus kit (D3S1385, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317 and D7S820), were determined from urban and countryside population of Córdoba (Argentina). All loci meet the Hardy-Weinberg expectation, and there is little evidence for alleles association between these nine loci. The results demonstrate that these loci can be useful for databasing purposes in human identification and parentage testing in the population of Córdoba (Argentina).     

A Windows-based software for common paternity and sibling analyses

A new Windows-based freeware for kinship analysis from DNA data is presented. This software can be used to calculate likelihood ratios and probabilities of paternity in trio and motherless cases, as well as in cases when a parent is lacking but there are data from the grandparents. It can also be used to compute the probability of two subjects being full-brothers or half-brothers.