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Major depressive disorder is a moderately heritable disorder characterized by one or more major depressive episodes. Laboratory tests to suport MDD diagnosis are not available. Diagnosis and treatment are based on various signs and symptoms not always fitting into strict diagnostic categories. Research for biological markers of neuropsychiatric disorders has been a challenge.

O Bisphenol A (BPA) é um xenoestrógeneo sintético capaz de ativar diversas vias de sinalização associadas a estrogénios. Este composto é utilizado na produção de plástico e das resinas de cola Epoxy, encontrando-se presente numa grande variedade de produtos para consumo humano. Consequentemente a exposição humana ao BPA é considerada generalizada e contínua. Estudos epidemiológicos verificaram correlação entre níveis elevados de BPA na urina e patogénese de doenças associadas ao envelhecimento celular como a aterosclerose. Neste estudo foram avaliados os efeitos da exposição prolongada ao BPA de concentrações encontradas em amostras biológicas humanas associadas a exposição ambiental e ocupacional, nomeadamente 10 ng/mL e 1 μg/ml.

Trabajo presentado en la V Meeting Asociación Española de Leguminosas, AEL (Eucarpia International Symposium on Protein Crops), celebrada en Pontevedra del 4 al 7 de mayo de 2015., Faba bean (Vicia faba L.) is an important crop because it is a legume with seeds that are a very relevant source of protein for human and animal consumption. It is an entomogamous partially allogamous crop that recently has been considered a candidate for low input and organic agriculture. So, the characterization of ex situ and on farm germplasm has a stronger importance for this crop. The aim of this work was to estimate the diversity within and among locally adapted faba bean accessions using the seeds morphological characteristics and the Inter-retrotransposon Amplification Polymorphism (IRAP) technique. We have studied four Portuguese accessions adapted to different agroecological conditions (two accessions of the major group and other two of the equina group) and, for control purposes, two inbred lines from CSIC belonging to the equina group. The plants were grown under pollinator-exclusion environment. The morphological characters analyzed were the number of seeds per pod, the 100 seed weight and the seed length, width and thickness. IRAP profiles were obtained using a primer for LTR regions of Athila retrotransposon. Cluster analysis using UPGMA and Principal Component Analysis (PCA) were performed to examine the variation among the studied accessions and to identify seed characters more relevant to distinguish the accessions analyzed. For the IRAP data a cluster analysis was also used and a Principal Coordinate Analysis (PCoordA) was performed. The cluster analysis of the morphological data combined with the PCA placed major and equina accessions into separated groups. PCA application moreover revealed that the main characters discriminating botanical groups were 100 seed weight and seed dimensions. Concerning the IRAP results, both the cluster analysis using UPGMA and the PCoordA separated the studied accessions in four groups. The two accessions of major faba bean formed one group quite distinct from all the equina accessions. Among the equina accessions the following three groups can be considered: (i) one group is formed by a Portuguese landrace presenting the highest degree of intravariation, which can be related to the great morphologic diversity existing in this accession; (ii) a second group formed by one inbred accession and (iii) a third group composed by one locally adapted equina Portuguese accession and the other inbred line. This study shows that seed morphological traits and the IRAP marker give similar results in what concerns the discrimination of faba bean major and equine groups. The IRAP marker could be a good choice to deeper assess genetic diversity in faba bean germplasm.

The functional importance of Epigenetics arise from DNA sequencing programs that show the need for another code to explain the dynamics of gene expression patterns observed along cell differentiation and organism development. In this context, the study of ribosomal gene silencing is in fact an excellent model to better understand the relationships that are established between gene transcription and chromatin topology, and to unravel the epigenetic switches evolved in the framework of gene expression.

Allopolyploidy is a significant evolutionary process, resulting in new species with diploid or greater chromosome complements derived from two or more progenitor species. We examined the chromosomal consequences of genomic merger in Arabidopsis suecica, the allotetraploid hybrid of Arabidopsis thaliana and Arabidopsis arenosa. Fluorescence in situ hybridization with centromere, nucleolus organizer region (NOR), and 5S rRNA gene probes reveals the expected numbers of progenitor chromosomes in natural A. suecica, but one pair of A. thaliana NORs and one pair of A. arenosa-derived 5S gene loci are missing. Similarly, in newly formed synthetic A. suecica-like allotetraploids, pairs of A. thaliana NORs are gained de novo, lost, and or transposed to A. arenosa chromosomes, with genotypic differences apparent between F3 siblings of the same F2 parent and between independent lines. Likewise, pairs of A. arenosa 5S genes are lost and novel linkages between 5S loci and NORs arise in synthetic allotetraploids. By contrast, the expected numbers of A. arenosa-derived NORs and A. thaliana-derived 5S loci are found in both natural and synthetic A. suecica. Collectively, these observations suggest that some, but not all, loci are unstable in newly formed A. suecica allotetraploids and can participate in a variety of alternative rearrangements, some of which resemble chromosomal changes found in nature.

In genetic hybrids, nucleolus formation on chromosomes inherited from only one parent is the epigenetic phenomenon, nucleolar dominance. By using Arabidopsis suecica, the allotetraploid hybrid of Arabidopsis thaliana and Arabidopsis arenosa, natural variation in nucleolar dominance was found to occur, providing a unique opportunity to examine homologous nucleolus organizer regions (NORs) in their active and inactive states. In A. suecica strain LC1, NORs derived from A. arenosa are active, whereas A. thalianaderived NORs are silenced. In A. suecica strain 9502, NORs of both parental species are active. When active, NORs are partially, but not fully, decondensed. Both active and inactive LC1 NORs colocalize with the nucleolus, contradicting the long-standing assumption that rRNA gene transcription drives nucleolus association. Collectively, these observations clarify the relationships among NOR chromatin topology, rRNA gene transcription, and NOR–nucleolus associations. A. suecica strains LC1 and 9502 have each lost one pair of A. thaliana NORs during evolution, and amplified fragmentlength polymorphism analysis further indicates that these strains are genetically very similar. These data suggest that nucleolar dominance can result from subtle genetic or epigenetic variation but is not a trait fundamental to a given interspecies hybrid combination

Nucleolar dominance is an enigma. The puzzle of differential amphiplasty has remained unresolved since it was first recognised and described in Crepis hybrids by Navashin in 1934. Here we review the body of knowledge that has grown out of the many models that have tried to find the genetic basis for differential rRNA gene expression in hybrids, and present a new interpretation. We propose and discuss a chromatin imprinting model which re-interprets differential amphiplasty in terms of two genomes of differing size occupying a common space within the nucleus, and with heterochromatin as a key player in the scenario. Difference in size between two parental genomes induces an inherited epigenetic mark in the hybrid that allows patterns of chromatin organization to have positional effects on the neighbouring domains. This chromatin imprinting model can be also used to explain complex genomic interactions which transcend nucleolar dominance and which can account for the overall characteristics of hybrids. Gene expression in hybrids, relative to parentage, is seen as being based on the nuclear location of the sequences concerned within their genomic environment, and where the presence of particular repetitive DNA sequences are ‘sensed’, and render silent the adjacent information.

[EN] Through the use of a silver staining technique three distinct regions can always be visualized in chromosomes:nucleolus organizer regions, centromere and telomere regions. The organization of the centromere region was studied in different phases of mitosis and meiosis. The centromere region was shown to be formed by an assembled dot-like structure with a market different complexity between mitotic and metaphase I chromosomes, being quadripartite in the former and bipartite in the latter. The nature of this difference is suggested to be related to the mechanism responsible to reductional division. The protein nature of these dots and their correspondence to the chromosome "core" and to the "scaffolding" is discussed. The presence of terminal dots in almost all telomeres and the existence of intercalar dots in some chromosomes are interpreted as being dependent on the individual phylogeny for each chromosome., [ES] Utilizando la técnica de tinción por el nitrato de plata, fue posible visualizar tres importantes regiones de los cromosomas de trigo panadero y de centeno: la centromérica, la telomérica y la del organizador nucleolar. Se observó que la región centrométrica era cosntituída por una estructura puntillada y densamente teñida cuya complejidad dependía de que los cromosomas estuviesen en la metafasis de mitosis o en la de la primera division de meiosis. En la última, la estructura del centrómetro era bipartida (Fig. 1A) mientras que en la primera se presentaba quadripartida (Fig. 1C, D). Se sugiere que esta estructura meiótica de los centrómeros pueda relacionarse con la división reducional que se sigue. Efectivamente los centrómeros son quadripartidos en la metafase ecuacional siguiente. Se discute la relación entre la constitución protéica de la estructura centromérica y los "core" y el "scaffolding" cromosómicos estudiados por varios autores. También se discute el origen de los puntos teloméricos e intercalares observados en los cromosomas cuando están teñidos por esta técnica.

Doutoramento em Biologia / Instituto Superior de Agronomia. Universidade de Lisboa Wheat is an essential crop for food and feed, due to its nutritional value and unique aptitude to produce gluten and their derived food products. It is thus essential to understand how increasingly common extreme weather events like heatwaves, defined as short periods of high temperatures (HT), affect wheat grain production and quality, and transcriptomic modulation. Thus, in order to identify wheat varieties with increased tolerance to HT, the objective of this work focused on the characterization of the already referred parameters in plants of several commercial varieties recommended to be used nowadays in Portugal and traditional varieties, submitted to high temperatures during grain filling. Using molecular markers, we showed that commercial genotypes have predicted good grain technological quality, based on the allelic composition of genes related with grain composition. Most commercial and traditional genotypes showed negative effects, induced by heatwave-like treatment, revealed by a decrease in grain number and weight, while protein content was increased. Also, through attenuated total reflection Fourier transform infrared (ATR-FTIR) analysis, we denoted the occurrence of alterations in grain polysaccharide composition induced by HT. Additionally, HT increased protein content variability in landraces and reduced it on commercial varieties. Regarding transcriptomic profiles assessed immediately after the HT treatment, traditional varieties revealed a significantly higher number of differentially expressed genes (DEGs), that include genes coding for heat shock proteins and cupins, and more similar HT responses than commercial varieties. Furthermore, Bancal and landraces DEGs appear to be more associated with several metabolic pathways, while in Antequera DEGs were preferentially related with transcription modulation and RNA and protein synthesis N/A