Página 1 dos resultados de 61 itens digitais encontrados em 0.011 segundos

‣ Cell-free fetal DNA in maternal plasma and noninvasive prenatal diagnosis

Ramos,Ester Silveira
Fonte: Escola de Enfermagem de Ribeirão Preto / Universidade de São Paulo Publicador: Escola de Enfermagem de Ribeirão Preto / Universidade de São Paulo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2006 Português
Relevância na Pesquisa
37.36605%
The noninvasive nature of the detection of fetal DNA in the maternal circulation represents the greatest advantage over the conventional methods of prenatal diagnosis. The applications of this methodology involve the detection of the fetal sex, and diagnosis, intra-uterine treatment, and evaluation of the prognosis of many diseases. Fetal cells detected in the maternal circulation have also been shown to be implicated in autoimmune diseases and to represent a potential source of stem cells. On the other hand, with the introduction of a technology that detects the fetal sex as early as at 6-8 weeks of gestation, there is the possibility of early abortion based on sex selection for social purposes. This implies an ethical discussion about the question. The introduction of new noninvasive techniques of prenatal diagnosis and the knowledge of the Nursing Team regarding new methodologies can be of great benefit to the mother and her children, and can help the Genetic Counseling of the families.

‣ Epigenesis of behavioural lateralization in humans and other animals

Schaafsma, S.M.; Riedstra, B.J.; Pfannkuche, K.A.; Bouma, A.; Groothuis, T.G.G.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.764165%
Despite several decades of research, the epigenesis of behavioural and brain lateralization is still elusive, although its knowledge is important in understanding developmental plasticity, function and evolution of lateralization, and its relationship with developmental disorders. Over the last decades, it has become clear that behavioural lateralization is not restricted to humans, but a fundamental principle in the organization of behaviour in vertebrates. This has opened the possibility of extending descriptive studies on human lateralization with descriptive and experimental studies on other vertebrate species. In this review, we therefore explore the evidence for the role of genes and environment on behavioural lateralization in humans and other animals. First, we discuss the predominant genetic models for human handedness, and conclude that their explanatory power alone is not sufficient, leaving, together with ambiguous results from adoption studies and selection experiments in animals, ample opportunity for a role of environmental factors. Next, we discuss the potential influence of such factors, including perinatal asymmetrical perception induced by asymmetrical head position or parental care, and social modulation, both in humans and other vertebrates...

‣ The Epigenesis of Planum Temporale Asymmetry in Twins

Eckert, Mark A.; Leonard, Christiana M.; Molloy, Elizabeth A.; Blumenthal, Jonathan; Zijdenbos, Alex; Giedd, Jay N.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/2002 Português
Relevância na Pesquisa
27.764165%
Variation in hemispheric asymmetry of the planum temporale (PT) has been related to verbal ability. The degree to which genetic and environmental factors mediate PT asymmetry is not known. This study examined the heritability for planar asymmetry in 12 dizygotic (DZ) and 27 monozygotic (MZ) male twin pairs who were between 6 and 16 years of age. There was weak but positive evidence for heritability of planar asymmetry. Co-twin similarity for planar asymmetry and Sylvian fissure morphology increased when excluding twins discordant for writing hand and when excluding twins exhibiting birth weight differences >20% from the analyses. Birth weight differences were also related to twin differences in total cerebral volume, but not central sulcus asymmetry. These results suggest that exogenous perinatal factors affect the epigenesis of planar asymmetry development.

‣ Mitochondria and metazoan epigenesis

Coffman, James A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.47393%
In eukaryotes, mitochondrial activity controls ATP production, calcium dynamics, and redox state, thereby establishing physiological parameters governing the transduction of biochemical signals that regulate nuclear gene expression. However, these activities are commonly assumed to fulfill a ‘housekeeping’ function: necessary for life, but an epiphenomenon devoid of causal agency in the developmental flow of genetic information. Moreover, it is difficult to perturb mitochondrial function without generally affecting cell viability. For these reasons little is known about the extent of mitochondrial influence on gene activity in early development. Recent discoveries pertaining to the redox regulation of key developmental signaling systems together with the fact that mitochondria are often asymmetrically distributed in animal embryos suggests that they may contribute spatial information underlying differential specification of cell fate. In many cases such asymmetries correlate with localization of genetic determinants (i.e., mRNAs or proteins), particularly in embryos that rely heavily on cell-autonomous means of cell fate specification. In such embryos the localized genetic determinants play a dominant role, and any developmental information contributed by the mitochondria themselves is likely to be less obvious and more difficult to isolate experimentally. Hence...

‣ Epigenetic modification of the X chromosome influences susceptibility to polycystic ovary syndrome

Hickey, T.; Legro, R.; Norman, R.
Fonte: Endocrine Society Publicador: Endocrine Society
Tipo: Artigo de Revista Científica
Publicado em //2006 Português
Relevância na Pesquisa
37.585295%
Context: The cause of polycystic ovary syndrome (PCOS) is unknown, although genetic and environmental influences are clearly implicated. Some genetic studies have suggested the involvement of X-linked genes in PCOS, but the influence of X chromosome inactivation (XCI) on manifestation of this disorder has not previously been examined. Objective: The objective of the study was to test the null hypothesis that XCI has no influence on clinical presentation of PCOS. Design: We examined patterns of XCI between sister pairs with the same genotype at a polymorphic locus on the X chromosome in families with PCOS. Setting: The study was conducted at a private practice. Participants: PCOS was defined as hyperandrogenemia with chronic anovulation. Forty families were studied in which DNA was obtained from at least one parent, the proband, and one sister that could be accurately diagnosed as being affected or unaffected. Main Outcome Measure(s): Relative expression of two X-linked alleles was determined, and the ratio of one to the other represented the pattern of XCI. Results: The statistical odds on a different clinical presentation between sisters was approximately 29 times higher in sister pairs with different patterns of XCI, compared with sister pairs with the same pattern of XCI (odds ratio 28.9; 95% confidence interval 4.0–206; P 0.0008). Conclusions: This study provides evidence to refute the null hypothesis and propose a closer inspection of X-linked genes in PCOS...

‣ Theory for the stability and regulation of epigenetic landscapes

Micheelsen, M.; Mitarai, N.; Sneppen, K.; Dodd, I.
Fonte: Institute of Physics Publishing Ltd. Publicador: Institute of Physics Publishing Ltd.
Tipo: Artigo de Revista Científica
Publicado em //2010 Português
Relevância na Pesquisa
27.36605%
Cells can often choose among several stably heritable phenotypes. Examples are the expressions of genes in eukaryotic cells where long chromosomal regions can adopt persistent and heritable silenced or active states that may be associated with positive feedback in dynamic modification of nucleosomes. We generalize this mechanism in terms of bistability associated with valleys in an epigenetic landscape. A transfer matrix method was used to rigorously follow the system through the disruptive process of cell division. This combined treatment of noisy dynamics both between and during cell division provides an efficient way to calculate the stability of alternative states in a broad range of epigenetic systems.; Mille A Micheelsen, Namiko Mitarai, Kim Sneppen and Ian B Dodd

‣ Investigating the potential role of genetic and epigenetic variation of DNA methyltransferase genes in hyperplastic polyposis syndrome

Drini, M.; Wong, N.; Scott, H.; Craig, J.; Dobrovic, A.; Hewitt, C.; Dow, C.; Young, J.; Jenkins, M.; Saffery, R.; Macrae, F.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
Relevância na Pesquisa
47.61778%
BACKGROUND: Hyperplastic Polyposis Syndrome (HPS) is a condition associated with multiple serrated polyps, and an increased risk of colorectal cancer (CRC). At least half of CRCs arising in HPS show a CpG island methylator phenotype (CIMP), potentially linked to aberrant DNA methyltransferase (DNMT) activity. CIMP is associated with methylation of tumor suppressor genes including regulators of DNA mismatch repair (such as MLH1, MGMT), and negative regulators of Wnt signaling (such as WIF1). In this study, we investigated the potential for interaction of genetic and epigenetic variation in DNMT genes, in the aetiology of HPS. METHODS: We utilized high resolution melting (HRM) analysis to screen 45 cases with HPS for novel sequence variants in DNMT1, DNMT3A, DNMT3B, and DNMT3L. 21 polyps from 13 patients were screened for BRAF and KRAS mutations, with assessment of promoter methylation in the DNMT1, DNMT3A, DNMT3B, DNMT3L MLH1, MGMT, and WIF1 gene promoters. RESULTS: No pathologic germline mutations were observed in any DNA-methyltransferase gene. However, the T allele of rs62106244 (intron 10 of DNMT1 gene) was over-represented in cases with HPS (p<0.01) compared with population controls. The DNMT1, DNMT3A and DNMT3B promoters were unmethylated in all instances. Interestingly...

‣ Epigenetic biomarkers in prostate cancer: current and future uses

Chiam, K.; Ricciardelli, C.; Bianco-Miotto, T.
Fonte: Elsevier Sci Ireland Ltd Publicador: Elsevier Sci Ireland Ltd
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Relevância na Pesquisa
27.47393%
Epigenome alterations are characteristic of nearly all human malignancies and include changes in DNA methylation, histone modifications and microRNAs (miRNAs). However, what induces these epigenetic alterations in cancer is largely unknown and their mechanistic role in prostate tumorigenesis is just beginning to be evaluated. Identification of the epigenetic modifications involved in the development and progression of prostate cancer will not only identify novel therapeutic targets but also prognostic and diagnostic markers. This review will focus on the use of epigenetic modifications as biomarkers for prostate cancer.; Karen Chiam, Carmela Ricciardelli and Tina Bianco-Miotto

‣ Reciprocal regulation of the basic helix-loop-helix/Per-Arnt-Sim partner proteins, Arnt and Arnt2, during neuronal differentiation

Hao, N.; Bhakti, V.; Peet, D.; Whitelaw, M.
Fonte: Oxford Univ Press Publicador: Oxford Univ Press
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
Relevância na Pesquisa
27.47393%
Basic helix–loop–helix/Per–Arnt–Sim (bHLH/PAS) transcription factors function broadly in development, homeostasis and stress response. Active bHLH/PAS heterodimers consist of a ubiquitous signal-regulated subunit (e.g., hypoxia-inducible factors, HIF-1α/2α/3α; the aryl hydrocarbon receptor, AhR) or tissue-restricted subunit (e.g., NPAS1/3/4, Single Minded 1/2), paired with a general partner protein, aryl hydrocarbon receptor nuclear translocator (Arnt or Arnt2). We have investigated regulation of the neuron-enriched Arnt paralogue, Arnt2. We find high Arnt/Arnt2 ratios in P19 embryonic carcinoma cells and ES cells are dramatically reversed to high Arnt2/Arnt on neuronal differentiation. mRNA half-lives of Arnt and Arnt2 remain similar in both parent and neuronal differentiated cells. The GC-rich Arnt2 promoter, while heavily methylated in Arnt only expressing hepatoma cells, is methylation free in P19 and ES cells, where it is bivalent with respect to active H3K4me3 and repressive H3K27me3 histone marks. Typical of a ‘transcription poised’ developmental gene, H3K27me3 repressive marks are removed from Arnt2 during neuronal differentiation. Our data are consistent with a switch to predominant Arnt2 expression in neurons to allow specific functions of neuronal bHLH/PAS factors and/or to avoid neuronal bHLH/PAS factors from interfering with AhR/Arnt signalling.; Nan Hao...

‣ Nutritional models of type 2 diabetes mellitus

Mühlhausler, B.S.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
Relevância na Pesquisa
37.36605%
In order to better understand the events which precede and precipitate the onset of type 2 diabetes (T2DM) several nutritional animal models have been developed. These models are generated by manipulating the diet of either the animal itself or its mother during her pregnancy and, in comparison to traditional genetic and knock out models, have the advantage that they more accurately reflect the aetiology of human T2DM. This chapter will discuss some of the most widely used nutritional models of T2DM: Diet-induced obesity (DIO) in adult rodents, and studies of prenatal and postnatal nutrition in offspring of mothers fed a low-protein diet or overnourished during pregnancy. Several common mechanisms have been identified through which these nutritional manipulations can lead to metabolic disease, including pancreatic beta-cell dysfunction, impaired insulin signalling in skeletal muscle and the excess accumulation of visceral adipose tissue and consequent deposition of non-esterified fatty acids in peripheral tissues resulting in peripheral insulin resistance. The following chapter will discuss each of these nutritional models, their application and relationship to human aetiology, and will highlight the important insights these models have provided into the pathogenesis of T2DM.; Beverly Sara Mühlhausler

‣ Analysis of model replication origins in Drosophila reveals new aspects of the chromatin landscape and its relationship to origin activity and the prereplicative complex

Liu, J.; Mconnell, K.; Dixon, M.; Calvi, B.R.
Fonte: The American Society for Cell Biology Publicador: The American Society for Cell Biology
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.47393%
Epigenetic regulation exerts a major influence on origins of DNA replication during development. The mechanisms for this regulation, however, are poorly defined. We showed previously that acetylation of nucleosomes regulates the origins that mediate developmental gene amplification during Drosophila oogenesis. Here we show that developmental activation of these origins is associated with acetylation of multiple histone lysines. Although these modifications are not unique to origin loci, we find that the level of acetylation is higher at the active origins and quantitatively correlated with the number of times these origins initiate replication. All of these acetylation marks were developmentally dynamic, rapidly increasing with origin activation and rapidly declining when the origins shut off and neighboring promoters turn on. Fine-scale analysis of the origins revealed that both hyperacetylation of nucleosomes and binding of the origin recognition complex (ORC) occur in a broad domain and that acetylation is highest on nucleosomes adjacent to one side of the major site of replication initiation. It was surprising to find that acetylation of some lysines depends on binding of ORC to the origin, suggesting that multiple histone acetyltransferases may be recruited during origin licensing. Our results reveal new insights into the origin epigenetic landscape and lead us to propose a chromatin switch model to explain the coordination of origin and promoter activity during development.

‣ A Sustained Dietary Change Increases Epigenetic Variation in Isogenic Mice

Li, Cheryl C. Y.; Cropley, Jennifer E.; Cowley, Mark J.; Preiss, Thomas; Martin, David I. K.; Suter, Catherine M.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.540322%
Epigenetic changes can be induced by adverse environmental exposures, such as nutritional imbalance, but little is known about the nature or extent of these changes. Here we have explored the epigenomic effects of a sustained nutritional change, excess dietary methyl donors, by assessing genomic CpG methylation patterns in isogenic mice exposed for one or six generations. We find stochastic variation in methylation levels at many loci; exposure to methyl donors increases the magnitude of this variation and the number of variable loci. Several gene ontology categories are significantly overrepresented in genes proximal to these methylation-variable loci, suggesting that certain pathways are susceptible to environmental influence on their epigenetic states. Long-term exposure to the diet (six generations) results in a larger number of loci exhibiting epigenetic variability, suggesting that some of the induced changes are heritable. This finding presents the possibility that epigenetic variation within populations can be induced by environmental change, providing a vehicle for disease predisposition and possibly a substrate for natural selection.; This work was supported by the Australian Research Council (DP0771859) and the National Health and Medical Research Council (#459412...

‣ Heritable epigenetic variation among maize inbreds

Eichten, Steve R.; Swanson-Wagner, Ruth A.; Schnable, James C.; Waters, Amanda J.; Hermanson, Peter J.; Liu, Sanzhen; Yeh, Cheng-Ting; Jia, Yi; Gendler, Karla; Freeling, Michael; Schnable, Patrick S.; Vaughn, Matthew W.; Springer, Nathan M.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica Formato: 14 pages
Português
Relevância na Pesquisa
37.617776%
Epigenetic variation describes heritable differences that are not attributable to changes in DNA sequence. There is the potential for pure epigenetic variation that occurs in the absence of any genetic change or for more complex situations that involve both genetic and epigenetic differences. Methylation of cytosine residues provides one mechanism for the inheritance of epigenetic information. A genome-wide profiling of DNA methylation in two different genotypes of Zea mays (ssp. mays), an organism with a complex genome of interspersed genes and repetitive elements, allowed the identification and characterization of examples of natural epigenetic variation. The distribution of DNA methylation was profiled using immunoprecipitation of methylated DNA followed by hybridization to a high-density tiling microarray. The comparison of the DNA methylation levels in the two genotypes, B73 and Mo17, allowed for the identification of approximately 700 differentially methylated regions (DMRs). Several of these DMRs occur in genomic regions that are apparently identical by descent in B73 and Mo17 suggesting that they may be examples of pure epigenetic variation. The methylation levels of the DMRs were further studied in a panel of near-isogenic lines to evaluate the stable inheritance of the methylation levels and to assess the contribution of cis- and trans- acting information to natural epigenetic variation. The majority of DMRs that occur in genomic regions without genetic variation are controlled by cis-acting differences and exhibit relatively stable inheritance. This study provides evidence for naturally occurring epigenetic variation in maize...

‣ Investigating the potential role of genetic and epigenetic variation of DNA methyltransferase genes in Hyperplastic Polyposis Syndrome

Drini, Musa; Wong, Nicholas C.; Scott, Hamish S.; Craig, Jeffrey M.; Dobrovic, Alexander; Hewitt, Chelsee A.; Dow, Christofer; Young, Joanne P.; Jenkins, Mark A.; Saffery, Richard; Macrae, Finlay A.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica Formato: 8 pages
Português
Relevância na Pesquisa
47.61778%
BACKGROUND Hyperplastic Polyposis Syndrome (HPS) is a condition associated with multiple serrated polyps, and an increased risk of colorectal cancer (CRC). At least half of CRCs arising in HPS show a CpG island methylator phenotype (CIMP), potentially linked to aberrant DNA methyltransferase (DNMT) activity. CIMP is associated with methylation of tumor suppressor genes including regulators of DNA mismatch repair (such as MLH1, MGMT), and negative regulators of Wnt signaling (such as WIF1). In this study, we investigated the potential for interaction of genetic and epigenetic variation in DNMT genes, in the aetiology of HPS. METHODS We utilized high resolution melting (HRM) analysis to screen 45 cases with HPS for novel sequence variants in DNMT1, DNMT3A, DNMT3B, and DNMT3L. 21 polyps from 13 patients were screened for BRAF and KRAS mutations, with assessment of promoter methylation in the DNMT1, DNMT3A, DNMT3B, DNMT3L MLH1, MGMT, and WIF1 gene promoters. RESULTS No pathologic germline mutations were observed in any DNA-methyltransferase gene. However, the T allele of rs62106244 (intron 10 of DNMT1 gene) was over-represented in cases with HPS (p<0.01) compared with population controls. The DNMT1, DNMT3A and DNMT3B promoters were unmethylated in all instances. Interestingly...

‣ Chronic high-fat diet in fathers programs β-cell dysfunction in female rat offspring; Chronic high-fat diet in fathers programs beta-cell dysfunction in female rat offspring

Ng, S.F.; Lin, R.; Laybutt, D.; Barres, R.; Owens, J.; Morris, M.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em //2010 Português
Relevância na Pesquisa
37.47393%
The global prevalence of obesity is increasing across most ages in both sexes. This is contributing to the early emergence of type 2 diabetes and its related epidemic. Having either parent obese is an independent risk factor for childhood obesity. Although the detrimental impacts of diet-induced maternal obesity on adiposity and metabolism in offspring are well established, the extent of any contribution of obese fathers is unclear, particularly the role of non-genetic factors in the causal pathway. Here we show that paternal high-fat-diet (HFD) exposure programs β-cell 'dysfunction' in rat F(1) female offspring. Chronic HFD consumption in Sprague-Dawley fathers induced increased body weight, adiposity, impaired glucose tolerance and insulin sensitivity. Relative to controls, their female offspring had an early onset of impaired insulin secretion and glucose tolerance that worsened with time, and normal adiposity. Paternal HFD altered the expression of 642 pancreatic islet genes in adult female offspring (P < 0.01); genes belonged to 13 functional clusters, including cation and ATP binding, cytoskeleton and intracellular transport. Broader pathway analysis of 2,492 genes differentially expressed (P < 0.05) demonstrated involvement of calcium-...

‣ La adicción a la nicotina: vulnerabilidad, epigénesis y modelos animales de estudio; Nicotine addiction: studies about vulnerability, epigenesis and animal models

Pastor, Verónica; Vazquez, Pablo; Corapi, Enrique Sebastian; Bernabeu, Ramon Oscar
Fonte: Cecilia Erica Reyna Publicador: Cecilia Erica Reyna
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Português
Relevância na Pesquisa
38.080583%
Este artículo es un resumen de las investigaciones actuales sobre los efectos de la nicotina en el sistema nervioso y su relación con la generación de una conducta adictiva. Al igual que otros psicoestimulantes, la nicotina activa la vía de la recompensa, la que también está involucrada en ciertas enfermedades psiquiátricas. Existen individuos que presentan una alta vulnerabilidad a volverse adictos a la nicotina. Esto puede deberse a factores tanto genéticos como epigenéticos y/o al entorno. En este trabajo se describen algunos factores epigenéticos implicados en estos fenómenos. Para este tipo de estudios, existen dos modelos comportamentales en animales: la autoadministración y el condicionamiento al lugar (CPP). Aquí, el CPP se explica en detalle por su potencial aplicación en humanos. Además, se describe la determinación comportamental de la actividad locomotora (lo cual indica el efecto causado por un psicoestimulante) como modelo para estudiar la vulnerabilidad individual a las drogas.; This article is a summary about the current research of nicotine effects on the nervous system and its relationship to the generation of an addictive behavior. Like other drugs of abuse, nicotine activates the reward pathway, which in turn is involved in certain psychiatric diseases. There are individuals who have a high vulnerability to nicotine addiction. This may be due to genetic and epigenetic factors and/or the environment. In this review...

‣ Systematic clustering of transcription start site landscapes

Zhao, Xiaobei; Valen, Eivind; Parker, Brian J.; Sandelin, Albin
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica Formato: 16 pages
Português
Relevância na Pesquisa
27.47393%
Genome-wide, high-throughput methods for transcription start site (TSS) detection have shown that most promoters have an array of neighboring TSSs where some are used more than others, forming a distribution of initiation propensities. TSS distributions (TSSDs) vary widely between promoters and earlier studies have shown that the TSSDs have biological implications in both regulation and function. However, no systematic study has been made to explore how many types of TSSDs and by extension core promoters exist and to understand which biological features distinguish them. In this study, we developed a new non-parametric dissimilarity measure and clustering approach to explore the similarities and stabilities of clusters of TSSDs. Previous studies have used arbitrary thresholds to arrive at two general classes: broad and sharp. We demonstrated that in addition to the previous broad/sharp dichotomy an additional category of promoters exists. Unlike typical TATA-driven sharp TSSDs where the TSS position can vary a few nucleotides, in this category virtually all TSSs originate from the same genomic position. These promoters lack epigenetic signatures of typical mRNA promoters and a substantial subset of them are mapping upstream of ribosomal protein pseudogenes. We present evidence that these are likely mapping errors...

‣ Evolution from XIST-Independent to XIST-Controlled X-Chromosome Inactivation: Epigenetic Modifications in Distantly Related Mammals

Chaumeil, Julie; Waters, Paul D.; Koina, Edda; Gilbert, Clément; Robinson, Terence J.; Marshall Graves, Jennifer A.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.47393%
X chromosome inactivation (XCI) is the transcriptional silencing of one X in female mammals, balancing expression of X genes between females (XX) and males (XY). In placental mammals non-coding XIST RNA triggers silencing of one X (Xi) and recruits a characteristic suite of epigenetic modifications, including the histone mark H3K27me3. In marsupials, where XIST is missing, H3K27me3 association seems to have different degrees of stability, depending on cell-types and species. However, the complete suite of histone marks associated with the Xi and their stability throughout cell cycle remain a mystery, as does the evolution of an ancient mammal XCI system. Our extensive immunofluorescence analysis (using antibodies against specific histone modifications) in nuclei of mammals distantly related to human and mouse, revealed a general absence from the mammalian Xi territory of transcription machinery and histone modifications associated with active chromatin. Specific repressive modifications associated with XCI in human and mouse were also observed in elephant (a distantly related placental mammal), as was accumulation of XIST RNA. However, in two marsupial species the Xi either lacked these modifications (H4K20me1), or they were restricted to specific windows of the cell cycle (H3K27me3...

‣ Global Analysis of Genetic, Epigenetic and Transcriptional Polymorphisms in Arabidopsis thaliana Using Whole Genome Tiling Arrays

Zhang, Xu; Shiu, Shinhan; Cal, Andrew; Borevitz, Justin O.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
47.61778%
Whole genome tiling arrays provide a high resolution platform for profiling of genetic, epigenetic, and gene expression polymorphisms. In this study we surveyed natural genomic variation in cytosine methylation among Arabidopsis thaliana wild accessions Columbia (Col) and Vancouver (Van) by comparing hybridization intensity difference between genomic DNA digested with either methylation-sensitive (HpaII) or -insensitive (MspI) restriction enzyme. Single Feature Polymorphisms (SFPs) were assayed on a full set of 1,683,620 unique features of Arabidopsis Tiling Array 1.0F (Affymetrix), while constitutive and polymorphic CG methylation were assayed on a subset of 54,519 features, which contain a 5'CCGG3' restriction site. 138,552 SFPs (1% FDR) were identified across enzyme treatments, which preferentially accumulated in pericentromeric regions. Our study also demonstrates that at least 8% of all analyzed CCGG sites were constitutively methylated across the two strains, while about 10% of all analyzed CCGG sites were differentially methylated between the two strains. Within euchromatin arms, both constitutive and polymorphic CG methylation accumulated in central regions of genes but under-represented toward the 5' and 3' ends of the coding sequences. Nevertheless...

‣ Cell-free fetal DNA in maternal plasma and noninvasive prenatal diagnosis; DNA fetal libre en el plasma materno y diagnóstico prenatal no invasivo; DNA livre fetal em plasma materno e diagnóstico pré-natal não invasivo

Ramos, Ester Silveira
Fonte: Universidade de São Paulo. Escola de Enfermagem de Ribeirão Preto Publicador: Universidade de São Paulo. Escola de Enfermagem de Ribeirão Preto
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Formato: application/pdf; application/pdf
Publicado em 01/12/2006 Português
Relevância na Pesquisa
27.764165%
The noninvasive nature of the detection of fetal DNA in the maternal circulation represents the greatest advantage over the conventional methods of prenatal diagnosis. The applications of this methodology involve the detection of the fetal sex, and diagnosis, intra-uterine treatment, and evaluation of the prognosis of many diseases. Fetal cells detected in the maternal circulation have also been shown to be implicated in autoimmune diseases and to represent a potential source of stem cells. On the other hand, with the introduction of a technology that detects the fetal sex as early as at 6-8 weeks of gestation, there is the possibility of early abortion based on sex selection for social purposes. This implies an ethical discussion about the question. The introduction of new noninvasive techniques of prenatal diagnosis and the knowledge of the Nursing Team regarding new methodologies can be of great benefit to the mother and her children, and can help the Genetic Counseling of the families.; La naturaleza no invasiva de la investigación del DNA fetal en la circulación materna representa una ventaja importante con relación a los métodos convencionales de diagnóstico prenatal. El uso de esta metodología implica la determinación del sexo fetal y el diagnóstico...