Search

Experimental results obtained by operating the Bray-Liebhafsky (BL) reaction in the CSTR are discussed. The dynamic behavior of the BL reaction is examined at several operation points in the concentration phase space, by varying the parameters.

Characteristics of air hardening steel are high hardness and low impact toughness. In order to increase the impact toughness while retaining high hardness value, studies were performed. One of the ways to achieve this is the alloying of specified steel with vanadium and application of appropriate heat treatment. Vanadium affects the solidification process of these alloys by narrowing of the temperature interval of crystallization. In addition, vanadium formed V6C5 carbides that block the growth of austenitic dendrites and structure makes fine-grained. Vanadium which forms V6C5 carbides is partly distributed between present phases in the steel; carbide (Cr,Fe)7C3 and austenite. Also, the presence of vanadium can enables the formation of (Cr,Fe)23C6 carbide and its precipitation in austenite during the cooling process. In local areas around fine carbide particles, austenite is transformed into martensite. In other words, vanadium reduces the amount of remained austenite and thus improves hardenbility ot the steel. In this way, better technical characteristics of these steels are obtained.

Fourteen metals and metalloids were determined in Conyza canadensis L. harvested from the fly ash landfill of the thermoelectric power plant “Kolubara” (Serbia). Fly ash samples were collected together with the plant samples and subjected to sequential extraction according to the three-step sequential extraction scheme proposed by the Community Bureau of Reference (BCR; now the Standards, Measurements and Testing Program). The contents of metals and metalloids were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) in plant root and the aboveground part and correlated with their contents in the fly ash samples. The bioconcentration factor (BCF) and translocation factors (TF) were calculated to access uptake of metals from fly ash and their translocation to the aboveground part. Results regarding As revealed that fly ash samples in the proximity of the active cassette had higher amounts of the element. Principal component analysis (PCA) showed that As had no impact on the classification of plant parts. BCF for As ranged from 1.44 to 23.8 and varied, depending on the investigated area; TF for As ranged from 0.43 to 2.61, indicating that the plant translocated As from root to shoot. In addition to As, Conyza canadensis L. exhibited efficient uptake of other metals from fly ash. According to the calculated BCF and TF, the plant retained Al, Fe and Cr in the root and translocated Zn, Cd, Cu and As from root to shoot in the course of the detoxifying process. [Projekat Ministarstva nauke Republike Srbije, br. 172030 i br. 172017]

The study focuses on the mental health and subjective well-being (SWB) of Serbian immigrants of the first generation in Canada. We wanted to examine if perceived discrimination, sense of control, self-esteem and perceived multiple discrepancy affect their mental health and SWB. Our results indicate that self-esteem and sense of control have a positive effect on mental health and all aspects of the SWB, while the perceived discrimination and perceived multiple discrepancy negatively affect SWB and mental health. Self-esteem was the most salient predictor of mental health, while the perceived multiple discrepancy was the most salient predictor of life satisfaction of Serbian immigrants.

Self-organization of cell-surface receptors in structurally distinct domains in the plasma membrane is of vital interest for correct cellular signaling. However, this dynamic process is difficult to study in cells with sufficiently high temporal and spatial resolution. We present here two quantitative high-resolution methods with single-molecule sensitivity, Fluorescence Correlation Spectroscopy (FCS) and pair-correlation Photoactivated Localization Microscopy (pcPALM), which enable nondestructive study of receptor diffusion and lateral organization at the nanoscale level. We introduce here the methods and review their application in studies of lateral organization of G Protein-Coupled Receptors (GPCRs). Examples from our own work on opioid receptor lateral organization are presented in order to illustrate the most recent advances in the field. [Projekat Ministarstva nauke Republike Srbije, br. 172015 i br. 45001]

Introduction. Despite intensive research, efforts and clinical investigations on pathogenesis of acute pancreatitis (AP) and system morbidity during the illness onset, mortality is still very high in the group of severe forms. A significantly high number of patients show moderate, self-limited forms of illness, with a minimal degree of systemic or local complications, with full recovery. However, some of them have a severe form, followed by a high percent of morbidity and mortality, and system organ failure. The distinction between mild and severe forms of AP within 24-48 hours of hospital admission is very important for the treatment of these patients. The usage of multifactorial scoring systems holds a lot of promise, reaching reliability in the disease severity estimation of approximately 70-80%. Objective. The main purpose of this prospective study was to assess the correlation of the Acute Physiology and Chronic Health Evaluation II (APACHE II) and the Bernard Organ Failure Score (BOFS) scoring systems in estimation of disease severity and outcome prediction. Methods. Sixty patients with AP participated in the study, all of them scored with the APACHE II and BOFS scores. The results were used for integration of laboratory and clinical parameters. Results. In our study, we had a highly significant correlation between the APACHE II and BOFS scores from the disease onset until the end of treatment. There was a highly significant correlation between these two scores and the serum C-reactive protein concentration level. Conclusion. The concept of the BOFS score has more advantages than the APACHE II score in the patients with severe forms of AP with organ dysfunction.

Asimple, rapid and accurate procedure for the quantitative determination of quercetin in its pure form and in formulations has been developed. The method is based on the spectrophotometric determination of a complex formed between quercetin and potassium titanyloxalate in 50 % ethanolic solutions. To characterize the quercetin titanyloxalato complex, the stability constants of the complex were determinated potentiometrically and spectrophotometrically at different temperatures (T = 26.0oC, 34oC and 39.0oC), as well as at different ionic strengths (I = 5.0x10-4 mol dm-3, 3.0x10-2 mol dm-3 and 6.0x10-2 mol dm-3) and the thermodynamic parameters were calculated. As quercetin is usually conjugated to vitamin C in pharmaceutical formulations, two procedures for the quantitative determination of quercetin by this complexing reaction were tested - both in the absence and presence of ascorbic acid. In both procedures, the Beer law was obeyed over the same concentration range of quercetin, i.e., 0.85 μg mL-1 - 16.9 μg mL-1. In the first procedure in the absence of ascorbic acid the molar absorptivity coefficient of the quercetin-titanyloxalate complex is a=2.49 x 104 mol-1 dm3 cm-1, Sandells sensitivity of the method is S = 1.35 x 10-2 μg cm-2 and the detection limit is d = 0.67 μg mL-1. Whereas, in the presence of ascorbic acid (second procedure) a = 3.04 x 104 mol-1 dm3 cm-1, S = 1.11 x 10-2 μg mL-1. The proposed method was verified for the determination of quercetin in pharmaceutical dosage forms. .

Plants that are able to accumulate and tolerate extraordinarily high concentrations of heavy metals (hyperaccumulators) can be used for phytoremediation (removal of contaminants from soils) or phytomining (growing a crop of plants to harvest the metals). Two moss species, Bryum capillare Hedw. and Ceratodon purpureus Hedw., were tested as potential phytoremedies under in vivo conditions on a coal ash disposal site in the surroundings of Obrenovac (NW Serbia). The content of various heavy metals (iron, manganese zinc, lead, nickel, cadmium, and copper) in the mosses and substrata were investigated over a period of three years. Iron and zinc were found to have the highest concentration in the mosses.

In order to examine the manner of iron uptake from the medium, in vitro culture of moss Bryum argenteum Hedw. (Bryaceae) was established. Under controlled conditions (16h light/8h dark, light intensity 47μmol m-2s-1 25±2°C), the moss was grown on basal MS medium or on MS medium enriched with various concentrations of ferri(III)citrate or potassium hexacyanoferrate(III). It was expected that with the organic chelate complex, Fe(III) ion will be more available for the plant. Sixty days after establishing in vitro culture, the plants grown on MS medium enriched with the ferri(III)citrate complex were developed better than plants grown on media with the potassium hexacyanoferrate(III) complex. To judge from plant production in vitro and in view of the fact that the two compounds were the only source of Fe(III), it would appear that the citrate complex makes Fe(III) ions more available than potassium hexacyanoferrate(III). Further research will examine the concentrations of Fe ion uptake by plants and potential use of these tiny moss plants for the phytomining, phytoremedies and hyperaccumulating purposes.

Soldiers may be exposed to traumatic stress during combat deployment and thus are at risk for developing posttraumatic stress disorder (PTSD). Genetic and epigenetic evidence suggests that PTSD is linked to forming stress-related memories. In the current study, we investigated post-deployment associations of PTSD symptoms with differential DNA methylation in a sample of Burundian soldiers returning from the African Union Mission in Somalia's war zone. We used a matched longitudinal study design to explore epigenetic changes associated with PTSD symptoms in N = 191 participants. PTSD symptoms and saliva samples were collected at 1-3 (t1) and 9-14 months (t2) after the return of the soldiers to their home base. Individuals with either worsening or improving PTSD symptoms were matched for age, stressful, traumatic and self-perpetrated events prior to the post-assessment, traumatic and violent experiences between the post- and the follow-up assessment, and violence experienced during childhood. A mixed model analysis was conducted to identify top nominally significantly differentially methylated genes, which were then used to perform a gene enrichment analysis. The linoleic acid metabolism pathway was significantly associated with post-deployment PTSD symptoms, after accounting for multiple comparisons. Linoleic acid has been linked to memory and immune related processes in previous research. Our findings suggest that differential methylation of linoleic acid pathway genes is associated with PTSD and thus may merit closer inspection as a possible mediator of resilience., (© 2024. The Author(s).)

Epigenetic processes allow plasticity in gene regulation in response to significant environmental events. Accumulating evidence suggests that effective psychotherapy is accompanied by epigenetic changes, rendering DNA methylation a potential biomarker of therapy success. Due to the central role of glucocorticoid dynamics in stress regulation and the alteration of aversive memories, glucocorticoid receptors are likely involved in the molecular processes that are required to successfully treat Posttraumatic Stress Disorder (PTSD). This study aimed to investigate the relationship between methylation at the glucocorticoid receptor gene (NR3C1) and PTSD treatment success of evidence-based psychotherapy. A sample of N = 153 conflict survivors from Northern Uganda (98 females and 55 males) with PTSD were treated with Narrative Exposure Therapy (NET). Diagnostic interviews and saliva sampling took place at pretreatment and 4 and 10 months after treatment completion. We investigated potential associations between PTSD symptom development and methylation changes at 38 CpG sites spanning NR3C1 over the three times of measurement using the repeated measures correlation. After accounting for multiple comparisons, DNA methylation at CpG site cg25535999 remained negatively associated with PTSD symptoms. These results were followed up by mixed models as well as structural equation modelling. These analyses revealed that treatment responders had a significant cg25535999 methylation increase after treatment with NET. Furthermore, lower methylation at cg25535999 pretreatment predicted a higher symptom improvement. Our results suggest different epigenetic profile dynamics at NR3C1 cg25535999 in therapy responders compared to non-responders and underscore the central role of glucocorticoid signaling in trauma-focused therapy., (© 2023. The Author(s).)

Background: Understanding the processes behind carotid plaque instability is necessary to develop methods for identification of patients and lesions with stroke risk. Here, we investigated molecular signatures in human plaques stratified by echogenicity as assessed by duplex ultrasound., Methods: Lesion echogenicity was correlated to microarray gene expression profiles from carotid endarterectomies (n=96). The findings were extended into studies of human and mouse atherosclerotic lesions in situ, followed by functional investigations in vitro in human carotid smooth muscle cells (SMCs)., Results: Pathway analyses highlighted muscle differentiation, iron homeostasis, calcification, matrix organization, cell survival balance, and BCLAF1 (BCL2 [B-cell lymphoma 2]-associated transcription factor 1) as the most significant signatures. BCLAF1 was downregulated in echolucent plaques, positively correlated to proliferation and negatively to apoptosis. By immunohistochemistry, BCLAF1 was found in normal medial SMCs. It was repressed early during atherogenesis but reappeared in CD68+ cells in advanced plaques and interacted with BCL2 by proximity ligation assay. In cultured SMCs, BCLAF1 was induced by differentiation factors and mitogens and suppressed by macrophage-conditioned medium. BCLAF1 silencing led to downregulation of BCL2 and SMC markers, reduced proliferation, and increased apoptosis. Transdifferentiation of SMCs by oxLDL (oxidized low-denisty lipoprotein) was accompanied by upregulation of BCLAF1, CD36, and CD68, while oxLDL exposure with BCLAF1 silencing preserved MYH (myosin heavy chain) 11 expression and prevented transdifferentiation. BCLAF1 was associated with expression of cell differentiation, contractility, viability, and inflammatory genes, as well as the scavenger receptors CD36 and CD68 . BCLAF1 expression in CD68+/BCL2+ cells of SMC origin was verified in plaques from MYH11 lineage-tracing atherosclerotic mice. Moreover, BCLAF1 downregulation associated with vulnerability parameters and cardiovascular risk in patients with carotid atherosclerosis., Conclusions: Plaque echogenicity correlated with enrichment of distinct molecular pathways and identified BCLAF1 , previously not described in atherosclerosis, as the most significant gene. Functionally, BCLAF1 seems necessary for survival and transdifferentiation of SMCs into a macrophage-like phenotype. The role of BCLAF1 in plaque vulnerability should be further evaluated.

The aftermath of traumatization lives on in the neural and epigenetic traces creating a momentum of affliction in the psychological and social realm. Can psychotherapy reorganise these memories through changes in DNA methylation signatures? Using a randomised controlled parallel group design, we examined methylome-wide changes in saliva samples of 84 female former child soldiers from Eastern DR Congo before and six months after Narrative Exposure Therapy. Treatment predicted differentially methylated positions (DMPs) related to ALCAM, RIPOR2, AFAP1 and MOCOS. In addition, treatment associations overlapped at gene level with baseline clinical and social outcomes. Treatment related DMPs are involved in memory formation-the key agent in trauma focused treatments-and enriched for molecular pathways commonly affected by trauma related disorders. Results were partially replicated in an independent sample of 53 female former child soldiers from Northern Uganda. Our results suggest a molecular impact of psychological treatment in women with war-related childhood trauma.Trial registration: Addressing Heightened Levels of Aggression in Traumatized Offenders With Psychotherapeutic Means (ClinicalTrials.gov Identifier: NCT02992561, 14/12/2016)., (© 2021. The Author(s).)

Extensive pharmacologic, genetic, and epigenetic research has linked the glucocorticoid receptor (GR) to memory processes, and to risk and symptoms of posttraumatic stress disorder (PTSD). In the present study we investigated the epigenetic pattern of 12 genes involved in the regulation of GR signaling in two African populations of heavily traumatized individuals: Survivors of the rebel war in northern Uganda ( n = 463) and survivors of the Rwandan genocide ( n = 350). The strongest link between regional methylation and PTSD risk and symptoms was observed for NTRK2 , which encodes the transmembrane receptor tropomyosin-related kinase B, binds the brain-derived neurotrophic factor, and has been shown to play an important role in memory formation. NTRK2 methylation was not related to trauma load, suggesting that methylation differences preexisted the trauma. Because NTRK2 methylation differences were predominantly associated with memory-related PTSD symptoms, and because they seem to precede traumatic events, we next investigated the relationship between NTRK2 methylation and memory in a sample of nontraumatized individuals ( n = 568). We found that NTRK2 methylation was negatively associated with recognition memory performance. Furthermore, fMRI analyses revealed NTRK2 methylation-dependent differences in brain network activity related to recognition memory. The present study demonstrates that NTRK2 is epigenetically linked to memory functions in nontraumatized subjects and to PTSD risk and symptoms in traumatized populations., Competing Interests: The authors declare no competing interest.

The neural cell adhesion molecule 1 (NCAM-1) has been implicated in several brain-related biological processes, including neuronal migration, axonal branching, fasciculation, and synaptogenesis, with a pivotal role in synaptic plasticity. Here, we investigated the evolutionary conserved role of NCAM-1 in learning and memory. First, we investigated sustained changes in ncam-1 expression following aversive olfactory conditioning in C. elegans using molecular genetic methods. Furthermore, we examined the link between epigenetic signatures of the NCAM1 gene and memory in two human samples of healthy individuals (N = 568 and N = 319) and in two samples of traumatized individuals (N = 350 and N = 463). We found that olfactory conditioning in C. elegans induced ncam-1 expression and that loss of ncam-1 function selectively impaired associative long-term memory, without causing acquisition, sensory, or short-term memory deficits. Reintroduction of the C. elegans or human NCAM1 fully rescued memory impairment, suggesting a conserved role of NCAM1 for memory. In parallel, DNA methylation of the NCAM1 promoter in two independent healthy Swiss cohorts was associated with memory performance. In two independent Sub-Saharan populations of conflict zone survivors who had faced severe trauma, DNA methylation at an alternative promoter of the NCAM1 gene was associated with traumatic memories. Our results support a role of NCAM1 in associative memory in nematodes and humans, and might, ultimately, be helpful in elucidating diagnostic markers or suggest novel therapy targets for memory-related disorders, like PTSD.

Background: The brain-derived neurotrophic factor (BDNF) rs6265 (Val66Met) Met allele is associated with early onset (≤ 19 years old) bipolar disorder (BD). Val66Met (G196A) creates a CpG site when the Val/G allele is present. We sought to study the methylation of the BDNF promoter and its interaction with Val66Met genotype in BD., Methods: Sex/age-matched previously genotyped DNA samples from BD-Type 1 cases [N = 166: early onset (≤ 19 years old) n = 79, late onset (> 20 years old) n = 87] and controls (N = 162) were studied. Pyrosequencing of four CpGs in Promoter-I, four CpGs in promoter-IV, and two CpGs in Promoter-IX (CpG2 includes G= Val allele) was performed. Logistic regression adjusting for batch effect was used to compare cases vs. controls. Analyses also included stratification by disease onset and adjustment for Val66Met genotype. Secondary exploratory analyses for the association of life stressors, comorbid substance abuse, and psychotropic use with methylation patterns were performed., Results: Comparing all BD cases vs. controls and adjusting for Val66Met genotype, BD cases had significantly higher methylation in promoter -IX/CPG-2 (p = 0.0074). This was driven by early onset cases vs. controls (p = 0.00039) and not late onset cases vs. controls (p = 0.2)., Limitation: Relatively small sample size., Conclusion: Early onset BD is associated with increased methylation of CpG site created by Val=G allele of the Val66Met variance. Further studies could include larger sample size and postmortem brain samples in an attempt to replicate these findings., Competing Interests: Declaration of Competing Interest Mark A. Frye: Previous Grant Support: Assurex Health, Mayo Foundation, Medibio. Consultancies: Actify Neurotherapies, Allergan, Intra-Cellular Therapies, Inc., Janssen, Myriad, Neuralstem Inc.,Takeda, Teva Pharmaceuticals. CME/Travel/Honoraria: American Physician Institute, CME Outfitters, Global Academy for Medical Education. None of the other authors have any reportable potential conflicts of interest., (Copyright © 2020. Published by Elsevier B.V.)

Loss of the tumor suppressor tuberous sclerosis complex 1 ( Tsc1 ) in the liver promotes gluconeogenesis and glucose intolerance. We asked whether this could be attributed to aberrant expression of small RNAs. We performed small-RNA sequencing on liver of Tsc1 -knockout mice, and found that miRNAs of the delta-like homolog 1 ( Dlk1 )-deiodinase iodothyronine type III ( Dio3 ) locus are up-regulated in an mTORC1-dependent manner. Sustained mTORC1 signaling during development prevented CpG methylation and silencing of the Dlk1-Dio3 locus, thereby increasing miRNA transcription. Deletion of miRNAs encoded by the Dlk1-Dio3 locus reduced gluconeogenesis, glucose intolerance, and fasting blood glucose levels. Thus, miRNAs contribute to the metabolic effects observed upon loss of TSC1 and hyperactivation of mTORC1 in the liver. Furthermore, we show that miRNA is a downstream effector of hyperactive mTORC1 signaling., Competing Interests: The authors declare no competing interest.

The risk of developing posttraumatic stress disorder (PTSD) increases with the number of traumatic event types experienced (trauma load) in interaction with other psychobiological risk factors. The NOTCH (neurogenic locus notch homolog proteins) signaling pathway, consisting of four different trans-membrane receptor proteins (NOTCH1-4), constitutes an evolutionarily well-conserved intercellular communication pathway (involved, e.g., in cell-cell interaction, inflammatory signaling, and learning processes). Its association with fear memory consolidation makes it an interesting candidate for PTSD research. We tested for significant associations of common genetic variants of NOTCH1-4 (investigated by microarray) and genomic methylation of saliva-derived DNA with lifetime PTSD risk in independent cohorts from Northern Uganda (N 1 = 924) and Rwanda (N 2 = 371), and investigated whether NOTCH-related gene sets were enriched for associations with lifetime PTSD risk. We found associations of lifetime PTSD risk with single nucleotide polymorphism (SNP) rs2074621 (NOTCH3) (p uncorrected = 0.04) in both cohorts, and with methylation of CpG site cg17519949 (NOTCH3) (p uncorrected = 0.05) in Rwandans. Yet, none of the (epi-)genetic associations survived multiple testing correction. Gene set enrichment analyses revealed enrichment for associations of two NOTCH pathways with lifetime PTSD risk in Ugandans: NOTCH binding (p corrected = 0.003) and NOTCH receptor processing (p corrected = 0.01). The environmental factor trauma load was significant in all analyses (all p < 0.001). Our integrated methodological approach suggests NOTCH as a possible mediator of PTSD risk after trauma. The results require replication, and the precise underlying pathophysiological mechanisms should be illuminated in future studies., (© 2018 The Authors. Psychophysiology published by Wiley Periodicals, Inc. on behalf of Society for Psychophysiological Research.)

Stress during pregnancy widely associates with epigenetic changes and psychiatric problems during childhood. Animal studies, however, show that under specific postnatal conditions prenatal stress may have other, less detrimental consequences for the offspring. Here, we studied mental health and epigenome-wide DNA methylation in saliva following intimate partner violence (IPV) during pregnancy in São Gonçalo, a Brazilian city with high levels of violence. Not surprisingly, mothers exposed to pregnancy IPV expressed elevated depression, PTSD and anxiety symptoms. Children had similar psychiatric problems when they experienced maternal IPV after being born. More surprisingly, when maternal IPV occurred both during (prenatal) and after pregnancy these problems were absent. Following prenatal IPV, genomic sites in genes encoding the glucocorticoid receptor ( NR3C1 ) and its repressor FKBP51 ( FKBP5 ) were among the most differentially methylated and indicated an enhanced ability to terminate hormonal stress responses in prenatally stressed children. These children also showed more DNA methylation in heterochromatin-like regions, which previously has been associated with stress/disease resilience. A similar relationship was seen in prenatally stressed middle-eastern refugees of the same age as the São Gonçalo children but exposed to postnatal war-related violence. While our study is limited in location and sample size, it provides novel insights on how prenatal stress may epigenetically shape resilience in humans, possibly through interactions with the postnatal environment. This translates animal findings and emphasizes the importance to account for population differences when studying how early life gene-environment interactions affects mental health.

Skin can acquire cadmium (Cd) by oral route, but there is paucity of data concerning cutaneous effects of this metal. Cd acquired by oral route can affect skin wound healing, but the effect of Cd on other activities involved in skin homeostasis, including skin immunity, are not explored. Using the rat model of 30-day oral administration of Cd (5 ppm and 50 ppm) in drinking water, basic aspects of immune-relevant activity of epidermal cells were examined. Dose-dependent Cd deposition in the the skin was observed (0.035 ± 0.02 µg/g and 0.127 ± 0.04 µg/g at 5 ppm and 50 ppm, respectively, compared to 0.012 ± 0.009 µg/g at 0 ppm of Cd). This resulted in skin inflammation (oxidative stress at both Cd doses and dose-dependent structural changes in the skin and the presence/activation of innate immunity cells). At low Cd dose inflammatory response (nitric oxide and IL-1β) was observed. Other inflammatory cytokines (IL-6 and TNF) response occurred at 50 ppm, which was increased further following skin sensitization with contact allergen dinitro-chlorobenzene (DNCB). Epidermal cells exposed to both Cd doses enhanced concanavalin A (ConA)-stimulated lymphocyte production of IL-17. This study showed for the first time the effect of the metal which gained access to the skin via gut on immune reactivity of epidermal cells. Presented data might be relevant for the link between dietary Cd and the risk of skin pathologies., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The probability to develop posttraumatic stress disorder (PTSD), characterized by vivid, intrusive emotional memories of the encountered traumatic events, depends - among other factors - on the number of previous traumatic experiences (traumatic load) and individual genetic vulnerability. So far, our knowledge regarding the biological underpinnings of PTSD is relatively sparse. Genome-wide association studies (GWAS) followed by independent replication might help to discover novel, so far unknown biological mechanisms associated with the development of traumatic memories. Here, a GWAS was conducted in N = 924 Northern Ugandan rebel war survivors and identified seven suggestively significant single nucleotide polymorphisms (SNPs; p ≤ 1 × 10 -5 ) for lifetime PTSD risk. Of these seven SNPs, the association of rs3852144 on chromosome 5 was replicated in an independent sample of Rwandan genocide survivors (N = 370, p < .01). While PTSD risk increased with accumulating traumatic experiences, the vulnerability was reduced in carriers of the minor G-allele in an additive manner. Correspondingly, memory for aversive pictures decreased with higher number of the minor G-allele in a sample of N = 2698 healthy Swiss individuals. Finally, investigations on N = 90 PTSD patients treated with Narrative Exposure Therapy indicated an additive effect of genotype on PTSD symptom change from pre-treatment to four months after treatment, but not between pre-treatment and the 10-months follow-up. In conclusion, emotional memory formation seems to decline with increasing number of rs3852144 G-alleles, rendering individuals more resilient to PTSD development. However, the impact on therapy outcome remains preliminary and further research is needed to determine how this intronic marker may affect memory processes in detail.

The large biological distance between genetic risk loci and their mechanistic consequences in the tissue of interest limits the ability to establish functionality of susceptibility variants for genetically complex traits. Such a biological gap may be reduced through the systematic study of molecular mediators of genomic action, such as epigenetic modification. Here, we report the identification of robust genetic estimators of whole-blood CpG methylation, which can serve as intermediate molecular traits amenable to association testing with other genetically complex traits. We describe the relationship between these estimators and gene expression, demonstrate their genome-wide applicability to association testing even in the absence of individual genotypic data, and show that these estimators powerfully identify methylation-related genomic loci associated with polygenic traits and common diseases, such as schizophrenia. The use of genetic estimators for blood DNA methylation, which are made publically available, can serve as a valuable tool for the identification of epigenetic underpinnings of complex traits.

Studies assessing the existence and magnitude of epistatic effects on complex human traits provide inconclusive results. The study of such effects is complicated by considerable increase in computational burden, model complexity, and model uncertainty, which in concert decrease model stability. An additional source introducing significant uncertainty with regard to the detection of robust epistasis is the biological distance between the genetic variation and the trait under study. Here we studied CpG methylation, a genetically complex molecular trait that is particularly close to genomic variation, and performed an exhaustive search for two-locus epistatic effects on the CpG-methylation signal in two cohorts of healthy young subjects. We detected robust epistatic effects for a small number of CpGs (N = 404). Our results indicate that epistatic effects explain only a minor part of variation in DNA-CpG methylation. Interestingly, these CpGs were more likely to be associated with gene-expression of nearby genes, as also shown by their overrepresentation in DNase I hypersensitivity sites and underrepresentation in CpG islands. Finally, gene ontology analysis showed a significant enrichment of these CpGs in pathways related to HPV-infection and cancer.