Forensic parameters and population structure based on 21 autosomal STRs with the investigator 24plex QS in mestizos from the Mexico City population.

Allele frequencies and forensic parameters for 21 STR autosomal markers (CSF1PO, D10S1248, D12S391, D13S317,D16S539, D18S51, D19S433, D1S1656,D21S11, D22S1045, D2S1338, D2S441, D3S1358, D5S818, D7S820, D8S1179, FGA, SE33, TH01, TPOX and vWA) were reported in 289 unrelated individuals from Mexico City, Mexico. In addition, an interpopulation analysis was performed including other world populations. In brief, the established population database of 21 autosomal STR markers in the present work is adequate for human identification purposes.

Students' foundational understanding of chemical reaction in the forensic science bachelor's degree program at the National Autonomous University of Mexico.

OBJECTIVE: To compare the understanding of the concept of chemical reaction-as operationalized by Bloom's taxonomy of cognitive levels-of students in forensic science bachelor's degree with that achieved by students majoring in chemistry, as a prerequisite for future professional collaboration and communication. MATERIALS AND METHODS: Using previously validated and published tests developed to assess students' knowledge, comprehension, and application of the concept of chemical reaction, we explored how conceptual understanding developed in students enrolled in (a) a forensic science degree program in a Mexican public university and in (b) chemistry undergraduate programs offered by the same university, and whether both groups achieved comparable attainment levels. FINDINGS AND IMPLICATIONS: Despite receiving considerably less chemical instruction, forensic science students achieved comparable levels of conceptual understanding of chemical reaction to those exhibited by chemistry students. This finding is encouraging because it might mean that future forensic scientists could graduate with a solid foundation of chemical knowledge. More research, particularly on the learning of other key concepts, will be needed to verify these initial findings.

Interdisciplinary approaches to the teaching of forensic science in the Forensic Science Undergraduate Program of the National Autonomous University of Mexico, before and after COVID-19.

In 2013, the Forensic Science Undergraduate Program (FSUP) at the National Autonomous University of Mexico was created in response to an alarming criminal situation in Mexico, as well as to the radical reform of its criminal justice system. Its mission is to educate and train ethical, critical, and humanistic forensic scientists capable of conducting inquiries that meet scientific quality standards and assist the justice system in firmly linking legal rulings to the available evidence. At the time, it was the first such program in the country, and the contributions that interdisciplinary forensic scientists could make to criminal investigations were largely unknown among forensic and legal practitioners. During its existence, providing an interdisciplinary, competence-based education to students has been one of the main challenges. To overcome it, teaching and assessment approaches-centered on the achievement of specifically forensic competencies as learning outcomes and the integration of forensic disciplines towards the resolution of simulated cases-have been devised to help develop the professional skill set expected of graduates. The COVID-19 pandemic led to adapting these approaches to distance or hybrid modes of learning, increasing their versatility and enriching the pedagogic repertoire of the FSUP. Currently, the main impact of the program lies in the successful incorporation of some of its graduates to agencies belonging to or related to the criminal justice system, such as the National Prosecutor's Office, the Commission for Truth and Justice for the Ayotzinapa Case, and the National Commission for the Search of Missing and Disappeared Persons, among others.

Development of an instrument for assessing the quality of forensic evidence and expert testimony from three feature-comparison methods: DNA, voice, and fingerprint analysis.

In a context of rising violence and long-lasting impunity, in 2008, Mexico's criminal justice system underwent a radical change from an inquisitorial model to an adversarial one, to make it more effective, transparent, and expeditious. The new system tasked judges with publicly determining the admissibility of forensic evidence, as well as assessing its technical quality and probative value-tasks for which they currently receive little to no training. With the aim of contributing to the consolidation of the adversarial model, a comparative framework-in the form of a checklist-of the analysis of fingerprints, DNA samples, and voice recordings was created. To do so, a review of the academic literature, published reports, and guidelines was performed. The collected data were synthesized and submitted to a panel of Mexican judges, who provided feedback on its adequacy. The framework focuses on the steps on which quality assurance of forensic evidence depends, organized in five discrete stages that span from the collection of samples at the scene of a crime to the presentation of evidence at trial, specifying the main technical criteria experts should state to allow a decision maker to examine its accuracy and reliability. Differences and commonalities among the three methods were identified, particularly in terms of how qualitative and quantitative analyses are performed in each. Besides its potential usefulness as an aid for judicial decision-making, the checklist could be a valuable resource for training programs aimed at judges, as well as quality assurance programs.

Dysregulation of miR-381-3p and miR-23b-3p in skeletal muscle could be a possible estimator of early post-mortem interval in rats.

BACKGROUND: The post-mortem interval (PMI) is the time elapsed since the dead of an individual until the body is found, which is relevant for forensic purposes. The miRNAs regulate the expression of some genes; and due to their small size, they can better support degradation, which makes them suitable for forensic analysis. In the present work, we evaluated the gene expression of miR-381-3p, miR-23b-3p, and miR-144-3p in skeletal muscle in a murine model at the early PMI. METHODS: We designed a rat model to evaluate the early PMI under controlled conditions. This model consisted in 25 rats divided into five groups of rats, that correspond to the 0, 3, 6, 12 and 24 hours of PMI. The 0 h-PMI was considered as the control group. Muscle samples were taken from each rat to analyze the expression of miR-381-3p, miR-23b-3p, and miR-144-3p by quantitative RT-PCR. The gene expression of each miRNA was expressed as Fold Change (FC) and compared among groups. To find the targets of these miRNAs and the pathways where they participate, we performed an in-silico analysis. From the gene targets of miR-381-3p identified in the silico analysis, the EPC1 gene was selected for gene expression analysis by quantitative RT-PCR in these samples. Also, to evaluate if miR-381-3p could predict the early PMI, a mixed effects model was calculated using its gene expression. RESULTS: An upregulation of miR-381-3p was found at 24 h-PMI compared with the control group of 0 h-PMI and (FC = 1.02 vs. FC = 1.96; p = 0.0079). This was the opposite for miR-23b-3p, which had a down-regulation at 24 h-PMI compared to 0 h-PMI (FC = 1.22 vs. FC = 0.13; p = 0.0079). Moreover, the gene expression of miR-381-3p increased throughout the first 24 h of PMI, contrary to miR-23b-3p. The targets of these two miRNAs, participate in biological pathways related to hypoxia, apoptosis, and RNA metabolism. The gene expression of EPC1 was found downregulated at 3 and 12 h of PMI, whereas it remained unchanged at 6 h and 24 h of PMI. Using a multivariate analysis, it was possible to predict the FC of miR-381-3p of all but 6 h-PMI analyzed PMIs. DISCUSSION: The present results suggest that miR-23b-3p and miR-381-3p participate at the early PMI, probably regulating the expression of some genes related to the autolysis process as EPC1 gene. Although the miR-381-3p gene expression is a potential estimator of PMI, further studies will be required to obtain better estimates.

Standardization of a Culture Medium for Megaselia scalaris (Diptera: Phoridae) for Entomotoxicological Studies.

One of the problems faced by entomotoxicological studies is the large variability of experimental set-ups and the absence of harmonized protocols to compare the data and results obtained by different research groups. Among the wide range of influencing factors on the development and growth of insects, food substrates are remarkably relevant. This article proposes a standardized growth medium to be employed in future entomotoxicological studies on the scuttle fly Megaselia scalaris (Loew, 1866), (Diptera: Phoridae). This species plays an important role in forensic cases related to the decomposition of human remains found indoors and/or in concealed environments, because of their small size and ability to enter these locations at an earlier time than many other insects. Because of these traits, it can be used for the estimation of the minimum postmortem interval (mPMI). We achieved the formulation of a medium that overcomes two traditional disadvantages of culture media used to raise necrophagous Diptera, the unknown media composition and different growth rates from those reared in tissue. The proposed medium is a known composition formulation, free of xenobiotics, in which M. scalaris shows growth rates and development times similar to those obtained when it is reared in tissue. This new diet might be used in future studies to test the effect of substances of forensic interest (prescription or illicit drugs, poisons, etc.) on the larval development time, helping to adjust the estimation of mPMI based on the presence of such substances. Additionally, the formulation revealed some interesting data about nutritional requirements of this species.

The NR3C1 gene expression is a potential surrogate biomarker for risk and diagnosis of posttraumatic stress disorder.

Posttraumatic Stress Disorder (PTSD) is an anxiety disorder which occurs after a traumatic event. The NR3C1 gene codes for the Glucocorticoid Receptor, which participate in the Hypothalamic-Pituitary-Adrenal (HPA) axis and is altered in PTSD patients. To evaluate whether the NR3C1 gene expression in peripheral blood could be useful as a diagnosis biomarker, a total of 32 PTSD patients and 59 healthy controls were analyzed with quantitative RT-PCR. Also, to assess if NR3C1 dysregulation is associated with hypocortisolism in PTSD patients, serum cortisol was quantified by ELISA in a subset of these samples. Significant NR3C1 over-expression was found in PTSD patients compared with controls, and this was higher in patients with acute PTSD. The Area Under the Curve (AUC) of NR3C1 gene expression was 0.797. The sensibility and specificity of NRC1 gene expression to diagnose PTSD was 62.5% and 89.8%, respectively. We also found that an up-regulation of NR3C1 increased the risk for being diagnosed with PTSD (OR= 12.8, 95%, CI 4-41.4). Finally, the NR3C1 gene expression was inversely related with serum cortisol in PTSD patients. The present results suggest that NR3C1 gene expression could be a promising biomarker for PTSD diagnosis and estimate the risk for disease development.

Kinetic and hysteretic behavior of ATP hydrolysis of the highly stable dimeric ATP synthase of Polytomella sp.

The F1FO-ATP synthase of the colorless alga Polytomella sp. exhibits a robust peripheral arm constituted by nine atypical subunits only present in chlorophycean algae. The isolated dimeric enzyme exhibits a latent ATP hydrolytic activity which can be activated by some detergents. To date, the kinetic behavior of the algal ATPase has not been studied. Here we show that while the soluble F1 sector exhibits Michaelis-Menten kinetics, the dimer exhibits a more complex behavior. The kinetic parameters (Vmax and Km) were obtained for both the F1 sector and the dimeric enzyme as isolated or activated by detergent, and this activation was also seen on the enzyme reconstituted in liposomes. Unlike other ATP synthases, the algal dimer hydrolyzes ATP on a wide range of pH and temperature. The enzyme was inhibited by oligomycin, DCCD and Mg-ADP, although oligomycin induced a peculiar inhibition pattern that can be attributed to structural differences in the algal subunit-c. The hydrolytic activity was temperature-dependent and exhibited activation energy of 4 kcal/mol. The enzyme also exhibited a hysteretic behavior with a lag phase strongly dependent on temperature but not on pH, that may be related to a possible regulatory role in vivo.

The mitochondrial respiratory chain of the secondary green alga Euglena gracilis shares many additional subunits with parasitic Trypanosomatidae.

The mitochondrion is an essential organelle for the production of cellular ATP in most eukaryotic cells. It is extensively studied, including in parasitic organisms such as trypanosomes, as a potential therapeutic target. Recently, numerous additional subunits of the respiratory-chain complexes have been described in Trypanosoma brucei and Trypanosoma cruzi. Since these subunits had apparently no counterparts in other organisms, they were interpreted as potentially associated with the parasitic trypanosome lifestyle. Here we used two complementary approaches to characterise the subunit composition of respiratory complexes in Euglena gracilis, a non-parasitic secondary green alga related to trypanosomes. First, we developed a phylogenetic pipeline aimed at mining sequence databases for identifying homologues to known respiratory-complex subunits with high confidence. Second, we used MS/MS proteomics after two-dimensional separation of the respiratory complexes by Blue Native- and SDS-PAGE both to confirm in silico predictions and to identify further additional subunits. Altogether, we identified 41 subunits that are restricted to E. gracilis, T. brucei and T. cruzi, along with 48 classical subunits described in other eukaryotes (i.e. plants, mammals and fungi). This moreover demonstrates that at least half of the subunits recently reported in T. brucei and T. cruzi are actually not specific to Trypanosomatidae, but extend at least to other Euglenozoa, and that their origin and function are thus not specifically associated with the parasitic lifestyle. Furthermore, preliminary biochemical analyses suggest that some of these additional subunits underlie the peculiarities of the respiratory chain observed in Euglenozoa.

Subunit-subunit interactions and overall topology of the dimeric mitochondrial ATP synthase of Polytomella sp.

Mitochondrial F1F0-ATP synthase of chlorophycean algae is a dimeric complex of 1600 kDa constituted by 17 different subunits with varying stoichiometries, 8 of them conserved in all eukaryotes and 9 that seem to be unique to the algal lineage (subunits ASA1-9). Two different models proposing the topological assemblage of the nine ASA subunits in the ATP synthase of the colorless alga Polytomella sp. have been put forward. Here, we readdressed the overall topology of the enzyme with different experimental approaches: detection of close vicinities between subunits based on cross-linking experiments and dissociation of the enzyme into subcomplexes, inference of subunit stoichiometry based on cysteine residue labelling, and general three-dimensional structural features of the complex as obtained from small-angle X-ray scattering and electron microscopy image reconstruction. Based on the available data, we refine the topological arrangement of the subunits that constitute the mitochondrial ATP synthase of Polytomella sp.

The fully-active and structurally-stable form of the mitochondrial ATP synthase of Polytomella sp. is dimeric.

Mitochondrial F(1)F(O)-ATP synthase of chlorophycean algae is a stable dimeric complex of 1,600 kDa. It lacks the classic subunits that constitute the peripheral stator-stalk and the orthodox polypeptides involved in the dimerization of the complex. Instead, it contains nine polypeptides of unknown evolutionary origin named ASA1 to ASA9. The isolated enzyme exhibited a very low ATPase activity (0.03 Units/mg), that increased upon heat treatment, due to the release of the F(1) sector. Oligomycin was found to stabilize the dimeric structure of the enzyme, providing partial resistance to heat dissociation. Incubation in the presence of low concentrations of several non-ionic detergents increased the oligomycin-sensitive ATPase activity up to 7.0-9.0 Units/mg. Incubation with 3% (w/v) taurodeoxycholate monomerized the enzyme. The monomeric form of the enzyme exhibited diminished activity in the presence of detergents and diminished oligomycin sensitivity. Cross-linking experiments carried out with the dimeric and monomeric forms of the ATP synthase suggested the participation of the ASA6 subunit in the dimerization of the enzyme. The dimeric enzyme was more resistant to heat treatment, high hydrostatic pressures, and protease digestion than the monomeric enzyme, which was readily disrupted by these treatments. We conclude that the fully-active algal mitochondrial ATP synthase is a stable catalytically active dimer; the monomeric form is less active and less stable. Monomer-monomer interactions could be mediated by the membrane-bound subunits ASA6 and ASA9, and may be further stabilized by other polypeptides such as ASA1 and ASA5.

Inhibition of Wnt and PI3K signaling modulates GSK-3beta activity and induces morphological changes in cortical neurons: role of tau phosphorylation.

Glycogen synthase kinase GSK-3beta has been identified as one of the major candidates mediating tau hyperphosphorylation at the same sites as those present in tau protein in brain from Alzheimer's disease (AD) patients. However, the signal transduction pathways involved in the abnormal activation of GSK-3beta, have not been completely elucidated. GSK-3beta activity is repressed by the canonical Wnt signaling pathway, but it is also modulated through the PI3K/Akt route. Recent studies have suggested that Wnt signaling might be involved in the pathophysiology of AD. On the other hand, modulators of the PI3K pathway might be reduced during aging leading to a sustained activation of GSK-3beta, which in turn would increase the risk of tau hyperphosphorylation. The role of Wnt and PI3K signaling inhibition on the extent of tau phosphorylation and neuronal morphology has not been completely elucidated. Thus, in the present investigation we analyzed the effects of different negative modulators of the Wnt and the PI3K pathways on GSK-3beta activation and phosphorylation of tau at the PHF-1 epitope in cortical cultured neurons and hippocampal slices from adult rat brain. Changes in the microtubule network were also studied. We found that a variety of Wnt and PI3K inhibitors, significantly increased tau phosphorylation at the PHF-1 site, induced the disarrangement of the microtubule network and the accumulation of tau within cell bodies. These changes correlated with alterations in neuronal morphology.