Quantification of human mitochondrial DNA using synthesized DNA standards

Successful mitochondrial DNA (mtDNA) forensic analysis depends on sufficient quantity and quality of mtDNA. A real-time quantitative PCR assay was developed to assess such characteristics in a DNA sample, which utilizes a duplex, synthetic DNA to ensure optimal quality assurance and quality control. The assay's 105-base pair target sequence facilitates amplification of degraded DNA and is minimally homologous to nonhuman mtDNA. The primers and probe hybridize to a region that has relatively few sequence polymorphisms. The assay can also identify the presence of PCR inhibitors and thus indicate the need for sample repurification. The results show that the assay provides information down to 10 copies and provides a dynamic range spanning seven orders of magnitude. Additional experiments demonstrated that as few as 300 mtDNA copies resulted in successful hypervariable region amplification, information that permits sample conservation and optimized downstream PCR testing. The assay described is rapid, reliable, and robust.     

Multiplex short tandem repeat amplification of low template DNA samples with the addition of proofreading enzymes

Abstract:  With <100 pg of template DNA, routine short tandem repeat (STR) analysis often fails, resulting in no or partial profiles and increased stochastic effects. To overcome this, some have investigated preamplification methods that include the addition of proofreading enzymes to the PCR cocktail. This project sought to determine whether adding proofreading polymerases directly in the STR amplification mixture would improve the reaction when little template DNA is available. Platinum Taq High Fidelity and GeneAmp High Fidelity were tested in Profiler Plus? STR reactions alone and in combination with AmpliTaq^® Gold. All reactions included the additional step of a post‐PCR purification step. With both pristine low template DNA and casework samples, the addition of these polymerases resulted in comparable or no improvement in the STR amplification signal. Further, stochastic effects and artifacts were observed equally across all enzyme conditions. Based on these studies, the addition of these proofreading enzymes to a multiplex STR amplification is not recommended for low template DNA work.     

Perceptions of Safety in Intimate Relationships: Group Differences Based on Gender and Setting

Intimate partner violence continues to be prevalent, resulting in negative consequences for the individuals involved and for society as a whole. Perceptions of safety in relationships where intimate partner violence is present is an understudied topic in the literature. The Safety Assessment of Future Events Scale (SAFE) was developed to assess respondents’ perceptions of safety in their intimate relationship. The purpose of this study was to examine whether group differences existed on respondents’ SAFE scores. 428 participants from community and clinic samples completed the SAFE and other measures contained in a southwest university’s marriage and family therapy clinic intake packet. ANCOVA was used to control for gender and setting in determining if group differences existed on the SAFE based on measures assessing interpersonal violence, relational adjustment, intrapersonal symptoms, and PTSD symptoms. Results indicated group differences based on gender, interpersonal violence victimization, and relational adjustment.     

Mandated Community Service in High School and Subsequent Civic Engagement: The Case of the “Double Cohort” in Ontario,Canada

In 1999, the Ontario provincial government introduced into its high school curriculum a requirement that students complete 40 h of volunteer community service before graduation. At the same time, the high school curriculum was shortened from five years to four. Consequently, the 2003 graduating class of Ontario high school students contained two cohorts, the first of the 4-year cohorts that was compelled to complete a mandated community service requirement, and the last of the 5-year cohorts that was not. Using a quasi-experimental design, we surveyed 1768 first-year university students in terms of their perceptions and attitudes about the nature and amount of previous volunteering, attitudes towards community service, current service involvement and other measures of civic and political engagement. Comparisons of the two cohorts indicate that, while there were discernible differences between the two cohorts in terms of their past record of community service, there were no differences in current attitudes and civic engagement that might plausibly be attributed to participation in the mandatory service program. Results are discussed with relation to the current debate concerning the impact of mandatory volunteering policies on intrinsic motivation to volunteer.

Recovery of Environmental Human DNA by Insects*,†

Abstract: We tested the hypotheses that foraging insects can acquire human DNA from the environment and that insect‐delivered human DNA is of sufficient quantity and quality to permit standard forensic analyses. Houseflies, German cockroaches, and camel crickets were exposed to dusty surfaces and then assayed for human mitochondrial and nuclear loci by conventional and qPCR, and multiplex STR amplification. Over two experiments, 100% of insect groups and 94% of dust controls tested positive for human DNA. Of 177 individuals, 33–67% tested positive and 13 yielded quantifiable human DNA (mean = 0.022 ± 0.006 ng; mean dust control = 2.448 ± 0.960 ng); four had at least one positive allele call for one or more locus; eight others showed multiple peaks at some loci. Results imply that application to routine forensic casework is limited given current detection methodology yet demonstrate the potential use of insects as environmental samplers for human DNA.