Progress and perspective on different strategies to achieve wake-up-free ferroelectric hafnia and zirconia-based thin films

In the last decade orthorhombic hafnia and zirconia films have attracted tremendous attention arising from the discovery of ferroelectricity at the nanoscale. However, an initial wake-up pre-cycling is usually needed to achieve a ferroelectric behaviour in these films. Recently, different strategies, such as microstructure tailoring, defect, bulk and interface engineering, doping, NH3 plasma treatment and epitaxial growth, have been employed to obtain wake-up free orthorhombic ferroelectric hafnia and zirconia films. In this work we review recent developments in obtaining polar hafnia and zirconia-based thin films without the need of any wake-up cycling. In particular, we discuss the rhombohedral phase of hafnia/ zirconia, which under a constrained environment exhibits wake-up-free ferroelectric behaviour. This phase could have a strong impact on the current investigations of ferroelectric binary oxide materials and pave the way toward exploiting ferroelectric behaviour for next-generation memory and logic gate applications.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding Contract UIDB/04650/2020 and by DST-SERB, Govt. of India through Grant Nr. ECR/2017/00006. R. F. Negrea and L. Pintilie acknowledge funding through project CEPROFER/ PN-III-P4-ID-PCCF-2016-0047 (contract 16/2018, funded by UEFISCDI). J.L.M-D. thanks the Royal Academy of Engineering Chair in Emerging Technologies Grant, CIET1819_24, the EPSRC grant EP/T012218/1- ECCS – EPSRC, and the grant EU-H2020-ERC-ADG # 882929, EROS

Reliability in the Identification of Midbrain Dopamine Neurons

Brain regions typically contain intermixed subpopulations of neurons with different connectivity and neurotransmitters. This complicates identification of neuronal phenotypes in electrophysiological experiments without using direct detection of unique molecular markers. A prime example of this difficulty is the identification of dopamine (DA) neurons in the midbrain ventral tegmental area (VTA). Although immunocytochemistry (ICC) against tyrosine hydroxylase (TH) is widely used to identify DA neurons, a high false negative rate for TH ICC following ex vivo electrophysiology experiments was recently reported, calling into question the validity of comparing DA and non-DA VTA neurons based on post-hoc ICC. However, in whole cell recordings from randomly selected rat VTA neurons we have found that TH labeling is consistently detected in ∼55% of neurons even after long recording durations (range: 2.5–150 min). This is consistent with our prior anatomical finding that 55% of VTA neurons are TH(+). To directly estimate a false negative rate for our ICC method we recorded VTA neurons from mice in which EGFP production is driven by the TH promoter. All 12 EGFP(+) neurons recorded with a K-gluconate internal solution (as used in our rat recordings) were strongly labeled by TH ICC (recording duration 16.6±1.8 min). However, using recording electrodes with an internal solution with high Cl− concentration reduced the intensity of TH co-labeling, in some cases to background (recording duration 16.7±0.9 min; n = 10). Thus TH is a highly reliable molecular marker for DA neurons in VTA patch clamp recordings provided compatible microelectrode solutions are used

Breakpoint Associated with a novel 2.3 Mb deletion in the VCFS region of 22q11 and the role of Alu (SINE) in recurring microdeletions

BACKGROUND: Chromosome 22q11.2 region is highly susceptible to rearrangement, specifically deletions that give rise to a variety of genomic disorders including velocardiofacial or DiGeorge syndrome. Individuals with this 22q11 microdeletion syndrome are at a greatly increased risk to develop schizophrenia. METHODS: Genotype analysis was carried out on the DNA from a patient with the 22q11 microdeletion using genetic markers and custom primer sets to define the deletion. Bioinformatic analysis was performed for molecular characterization of the deletion breakpoint sequences in this patient. RESULTS: This 22q11 deletion patient was established to have a novel 2.3 Mb deletion with a proximal breakpoint located between genetic markers RH48663 and RH48348 and a distal breakpoint between markers D22S1138 and SHGC-145314. Molecular characterization of the sequences at the breakpoints revealed a 270 bp shared sequence of the breakpoint regions (SSBR) common to both ends that share >90% sequence similarity to each other and also to short interspersed nuclear elements/Alu elements. CONCLUSION: This Alu sequence like SSBR is commonly in the proximity of all known deletion breakpoints of 22q11 region and also in the low copy repeat regions (LCRs). This sequence may represent a preferred sequence in the breakpoint regions or LCRs for intra-chromosomal homologous recombination mechanisms resulting in common 22q11 deletion

Molecular Basis for the Recognition of Adenomatous Polyposis Coli by the Discs Large 1 Protein

The human Discs Large 1 (DLG1) protein uses two of its three PDZ domains to interact with the C-terminal peptide of the Adenomatous Polyposis Coli (APC) tumor suppressor protein. The DLG1/APC complex inhibits the cell cycle progression from the G0/G1 to the S phase, regulates epithelial cell migration and morphogenesis, and is required for polarization of the microtubule cytoskeleton. However, the molecular details of how DLG1 recognizes APC is not clear. In this study, we performed biochemical and biophysical assays to investigate the interactions between PDZ domains of DLG1 and the C-terminal peptide of APC. In addition, we determined the crystal structures of the PDZ1 and PDZ2 domains of DLG1 each in complex with the C-terminal 11-residue peptide of APC. Our biochemical, biophysical, and structural results revealed structural elements and residues on PDZ1 and PDZ2 domains of DLG1 and on APC crucial for their mutual interaction. In particular, our results show that the β2/β3 loops of PDZ1 and PDZ2 play important roles in contributing to the binding affinities between PDZ domains and APC, through interacting with the residues upstream of the canonical PDZ-binding S/T-X-V motif. The results provide new insights into the binding mode of a defined C-terminal segment of APC by the PDZ domains of DLG1

Dysregulation of DGCR6 and DGCR6L: psychopathological outcomes in chromosome 22q11.2 deletion syndrome

Chromosome 22q11.2 deletion syndrome (22q11DS) is the most common microdeletion syndrome in humans. It is typified by highly variable symptoms, which might be explained by epigenetic regulation of genes in the interval. Using computational algorithms, our laboratory previously predicted that DiGeorge critical region 6 (DGCR6), which lies within the deletion interval, is imprinted in humans. Expression and epigenetic regulation of this gene have not, however, been examined in 22q11DS subjects. The purpose of this study was to determine if the expression levels of DGCR6 and its duplicate copy DGCR6L in 22q11DS subjects are associated with the parent-of-origin of the deletion and childhood psychopathologies. Our investigation showed no evidence of parent-of-origin-related differences in expression of both DGCR6 and DGCR6L. However, we found that the variability in DGCR6 expression was significantly greater in 22q11DS children than in age and gender-matched control individuals. Children with 22q11DS who had anxiety disorders had significantly lower DGCR6 expression, especially in subjects with the deletion on the maternal chromosome, despite the lack of imprinting. Our findings indicate that epigenetic mechanisms other than imprinting contribute to the dysregulation of these genes and the associated childhood psychopathologies observed in individuals with 22q11DS. Further studies are now needed to test the usefulness of DGCR6 and DGCR6L expression and alterations in the epigenome at these loci in predicting childhood anxiety and associated adult-onset pathologies in 22q11DS subjects

Frequency of 22q11.2 microdeletion in children with congenital heart defects in western poland

<p>Abstract</p> <p>Background</p> <p>The 22q11.2 microdeletion syndrome (22q11.2 deletion syndrome -22q11.2DS) refers to congenital abnormalities, including primarily heart defects and facial dysmorphy, thymic hypoplasia, cleft palate and hypocalcaemia. Microdeletion within chromosomal region 22q11.2 constitutes the molecular basis of this syndrome. The 22q11.2 microdeletion syndrome occurs in 1/4000 births. The aim of this study was to determine the frequency of 22q11.2 microdeletion in 87 children suffering from a congenital heart defect (conotruncal or non-conotruncal) coexisting with at least one additional 22q11.2DS feature and to carry out 22q11.2 microdeletion testing of the deleted children's parents. We also attempted to identify the most frequent heart defects in both groups and phenotypic traits of patients with microdeletion to determine selection criteria for at risk patients.</p> <p>Methods</p> <p>The analysis of microdeletions was conducted using fluorescence <it>in situ </it>hybridization (FISH) on metaphase chromosomes and interphase nuclei isolated from venous peripheral blood cultures. A molecular probe (Tuple) specific to the <it>HIRA (TUPLE1, DGCR1</it>) region at 22q11 was used for the hybridisation.</p> <p>Results</p> <p>Microdeletions of 22q11.2 region were detected in 13 children with a congenital heart defect (14.94% of the examined group). Microdeletion of 22q11.2 occurred in 20% and 11.54% of the conotruncal and non-conotruncal groups respectively. Tetralogy of Fallot was the most frequent heart defect in the first group of children with 22q11.2 microdeletion, while ventricular septal defect and atrial septal defect/ventricular septal defect were most frequent in the second group. The microdeletion was also detected in one of the parents of the deleted child (6.25%) without congenital heart defect, but with slight dysmorphism. In the remaining children, 22q11.2 microdeletion originated <it>de novo</it>.</p> <p>Conclusions</p> <p>Patients with 22q11.2DS exhibit wide spectrum of phenotypic characteristics, ranging from discreet to quite strong. The deletion was inherited by one child. Our study suggests that screening for 22q11.2 microdeletion should be performed in children with conotruncal and non-conotruncal heart defects and with at least one typical feature of 22q11.2DS as well as in the deleted children's parents.</p

Translational toxicology in setting occupational exposure limits for dusts and hazard classification – a critical evaluation of a recent approach to translate dust overload findings from rats to humans

Background We analyze the scientific basis and methodology used by the German MAK Commission in their recommendations for exposure limits and carcinogen classification of “granular biopersistent particles without known specific toxicity” (GBS). These recommendations are under review at the European Union level. We examine the scientific assumptions in an attempt to reproduce the results. MAK’s human equivalent concentrations (HECs) are based on a particle mass and on a volumetric model in which results from rat inhalation studies are translated to derive occupational exposure limits (OELs) and a carcinogen classification. Methods We followed the methods as proposed by the MAK Commission and Pauluhn 2011. We also examined key assumptions in the metrics, such as surface area of the human lung, deposition fractions of inhaled dusts, human clearance rates; and risk of lung cancer among workers, presumed to have some potential for lung overload, the physiological condition in rats associated with an increase in lung cancer risk. Results The MAK recommendations on exposure limits for GBS have numerous incorrect assumptions that adversely affect the final results. The procedures to derive the respirable occupational exposure limit (OEL) could not be reproduced, a finding raising considerable scientific uncertainty about the reliability of the recommendations. Moreover, the scientific basis of using the rat model is confounded by the fact that rats and humans show different cellular responses to inhaled particles as demonstrated by bronchoalveolar lavage (BAL) studies in both species. Conclusion Classifying all GBS as carcinogenic to humans based on rat inhalation studies in which lung overload leads to chronic inflammation and cancer is inappropriate. Studies of workers, who have been exposed to relevant levels of dust, have not indicated an increase in lung cancer risk. Using the methods proposed by the MAK, we were unable to reproduce the OEL for GBS recommended by the Commission, but identified substantial errors in the models. Considerable shortcomings in the use of lung surface area, clearance rates, deposition fractions; as well as using the mass and volumetric metrics as opposed to the particle surface area metric limit the scientific reliability of the proposed GBS OEL and carcinogen classification.International Carbon Black Associatio

Significant Association of Estrogen Receptor Binding Site Variation with Bipolar Disorder in Females

Major depression is nearly twice as prevalent in women compared to men. In bipolar disorder, depressive episodes have been reported to be more common amongst female patients. Furthermore, periods of depression often correlate with periods of hormonal fluctuations. A link between hormone signaling and these mood disorders has, therefore, been suggested to exist in many studies. Estrogen, one of the primary female sex hormones, mediates its effect mostly by binding to estrogen receptors (ERs). Nuclear ERs function as transcription factors and regulate gene transcription by binding to specific DNA sequences. A nucleotide change in the binding sequence might alter the binding efficiency, which could affect transcription levels of nearby genes. In order to investigate if variation in ER DNA-binding sequences may be involved in mood disorders, we conducted a genome-wide study of ER DNA-binding in patients diagnosed with major depression or bipolar disorder. Association studies were performed within each gender separately and the results were corrected for multiple testing by the Bonferroni method. In the female bipolar disorder material a significant association result was found for rs6023059 (corrected p-value = 0.023; odds ratio (OR) 0.681, 95% confidence interval (CI) 0.570–0.814), a single nucleotide polymorphism (SNP) placed downstream of the gene coding for transglutaminase 2 (TGM2). Thus, females with a specific genotype at this SNP may be more vulnerable to fluctuating estrogen levels, which may then act as a triggering factor for bipolar disorder

Host Genetics and HIV-1: The Final Phase?

This is a crucial transition time for human genetics in general, and for HIV host genetics in particular. After years of equivocal results from candidate gene analyses, several genome-wide association studies have been published that looked at plasma viral load or disease progression. Results from other studies that used various large-scale approaches (siRNA screens, transcriptome or proteome analysis, comparative genomics) have also shed new light on retroviral pathogenesis. However, most of the inter-individual variability in response to HIV-1 infection remains to be explained: genome resequencing and systems biology approaches are now required to progress toward a better understanding of the complex interactions between HIV-1 and its human host