ABSTRACT
The acid phosphatase (AP) test is a routine assay used to screen casework items for the possible presence of semen. This colour test is carried out on filter paper which is retained after testing. Two-year-old AP test papers were found to contain sufficient DNA for short tandem repeat (STR) profiling. Prior to polymerase chain reaction (PCR) amplification, the DNA was preferentially separated into sperm depleted and sperm enriched cell fractions. The implication of these findings for past and present cases is discussed.
Subject(s)
Acid Phosphatase/analysis , Clinical Enzyme Tests/methods , DNA Fingerprinting/methods , Paper/standards , Semen/enzymology , Adolescent , Forensic Medicine/methods , Humans , Male , Tandem Repeat Sequences , Time FactorsABSTRACT
Hematophagus arthropod bloodmeals may be useful in identifying individual hosts. To examine the application of human lice as a forensic tool, that is, as evidence of physical contact between individuals, body lice from a laboratory colony and head lice, collected from the head of infested children, were studied. The DNA profile of an individual was detectable in the pooled bloodmeals of two body lice, up to 20 h postfeeding. A mixed DNA profile of two hosts was identifiable in the pooled bloodmeals of three lice, for 3 h postfeeding. By pooling the bloodmeals of three adult and three nymphal head lice, a mixed DNA profile was obtained. These results indicate that, in criminal cases where there has been close contact between assailant and victim, louse bloodmeals should not be overlooked as potentially critical evidence.
Subject(s)
Entomology/methods , Forensic Medicine/methods , Lice Infestations , Pediculus , Animal Feed , Animals , Blood/parasitology , DNA/genetics , DNA/isolation & purification , Gene Expression Profiling , Genetic Markers , Humans , Pediculus/genetics , Polymorphism, GeneticABSTRACT
Chorionic villus sampling (CVS), prior to pregnancy termination (pre-termination CVS), is suggested as a tool for forensic paternity testing. Unlike the abortion material, which consists of ruptured tissues of fetal and maternal origin, extra-embryonic membranes obtained through CVS can provide an uncontaminated source of fetal tissue for genotyping. We discuss the possibility of confined placental mosaicism (CPM) and its implications on the polymerase chain reaction (PCR) based analyses of short tandem repeats (STRs) and the D1S80 loci.
Subject(s)
Abortion, Legal , Chorionic Villi Sampling , Paternity , Rape , Adolescent , Alleles , Child Abuse, Sexual , DNA/analysis , Female , Genotype , HLA-DQ Antigens/analysis , Humans , Male , Minisatellite Repeats/genetics , Polymerase Chain Reaction , PregnancyABSTRACT
An intact condom, reputedly used during a rape, was submitted for forensic examination. Conventional biochemistry results indicated that blood found on one side of the condom may have originated from the victim. Semen from the other side of the condom was not characterizable by conventional biochemical methods. Pubic hairs recovered from the condom matched those of the victim and not those of the suspect. Testing the blood and semen from the condom by DNA analysis gave the profile of the victim from the blood and the profile of the suspect from the semen.
Subject(s)
Condoms , Rape/legislation & jurisprudence , Adolescent , Blood Stains , DNA Fingerprinting , Female , Humans , Semen/chemistryABSTRACT
Mouse teratocarcinoma cells induced to differentiate in vitro undergo a massive (30%) demethylation of DNA. A similar undermethylation is also observed in the mouse extraembryonic membranes, the yolk sac and placenta. In both cases, the decrease in methyl moieties occurs at a large number of CpG sites spread out over the entire genome, as indicated by a restriction enzyme analysis of several mouse genes including dhfr, beta-major globin, and the H-2K gene family. In contrast to this, the embryo itself appears to undergo methylation de novo during early stages of embryogenesis. Thus, as opposed to somatic cells, events during early mouse development are associated with wide variations in the level of DNA methylation. Although these changes in DNA methylation seem to be an integral part of the differentiation process, its relation to specific gene expression is still unclear.
Subject(s)
Cell Differentiation , DNA, Neoplasm/genetics , Teratoma/physiopathology , Animals , Cell Line , Cells, Cultured , DNA/isolation & purification , Female , Genes , L Cells/physiology , Male , Methylation , Mice , Plasmids , Pregnancy , Tetrahydrofolate Dehydrogenase/geneticsABSTRACT
The distribution of sites that can be methylated was analyzed in the Chinese hamster adenine phosphoribosyl-transferase (aprt) gene and the patterns of methylation of this gene and the mouse dihydrofolate reductase (dhfr) gene were studied by using CpG restriction enzymes. Both genes were found to be unmethylated completely at their 5'-end region and methylated heavily throughout the rest of the gene. Because the hamster aprt gene can be inhibited by DNA methylation in vivo, the results suggest that 5' undermethylation of this gene may be a necessary condition for its expression. The pattern of methylation of each of these two genes was similar in sperm and all other somatic tissue DNAs. This is in contrast to many tissue-specific genes that were found to be highly methylated in sperm DNA and undermethylated in the tissue in which they are expressed. This result is consistent with the fact that both aprt and dhfr are key enzymes in the biosynthesis of nucleotides and therefore expected to be synthesized in all cells.
