Higher frequency of legitimate pollinators and fruit set of autotetraploid trees of Libidibia ferrea (Leguminosae) compared to diploids in a mixed tropical urban population

Journal of Plant Research - In mixed-ploidy populations, newly formed polyploids initially occur at low frequencies when compared to diploids. However, polyploidy may lead to morphological and...     

The Role of Glia in Addiction: Dopamine as a Modulator of Glial Responses in Addiction

Cellular and Molecular Neurobiology - Addiction is a chronic and potentially deadly disease considered a global health problem. Nevertheless, there is still no ideal treatment for its management....     

Autotrophic nitrite removal in the cathode of microbial fuel cells

Nitrification to nitrite (nitritation process) followed by reduction to dinitrogen gas decreases the energy demand and the carbon requirements of the overall process of nitrogen removal. This work studies autotrophic nitrite removal in the cathode of microbial fuel cells (MFCs). Special attention was paid to determining whether nitrite is used as the electron acceptor by exoelectrogenic bacteria (biologic reaction) or by graphite electrodes (abiotic reaction). The results demonstrated that, after a nitrate pulse at the cathode, nitrite was initially accumulated; subsequently, nitrite was removed. Nitrite and nitrate can be used interchangeably as an electron acceptor by exoelectrogenic bacteria for nitrogen reduction from wastewater while producing bioelectricity. However, if oxygen is present in the cathode chamber, nitrite is oxidised via biological or electrochemical processes. The identification of a dominant bacterial member similar to Oligotropha carboxidovorans confirms that autotrophic denitrification is the main metabolism mechanism in the cathode of an MFC.     

Cell specific patterns of methylation in the human placenta

Epigenetic processes, such as DNA methylation, are known to regulate tissue specific gene expression. We explored this concept in the placenta to define whether DNA methylation is cell-type specific. Cytotrophoblasts and fibroblasts were isolated from normal midtrimester placentas. Using immunocytochemistry, we demonstrated 95% purity for cytotrophoblasts and 60–70% for fibroblasts. We compared DNA methylation profiles from cytotrophoblasts, fibroblasts and whole placental villi using bisulfite modified genomic DNA hybridized to the Illumina Methylation27 array. Euclidean cluster analysis of the DNA methylation profiles showed two main clusters, one containing cytotrophoblasts and placenta, the other fibroblasts. Differential methylation analysis identified 442 autosomal CpG sites that differed between cytotrophoblasts and fibroblasts, 315 between placenta and fibroblasts and 61 between placenta and cytotrophoblasts. Three candidate methylation differences were validated by targeted pyrosequencing assays. Pyrosequencing assays were developed for CpG sites less methylated in cytotrophoblasts than fibroblasts mapping to the promoter region of the beta subunit of human chorionic gonadotropin 5 (CGB5), as well as two CpG sites mapping to each of two tumor suppressor genes. Our data suggest that epigenetic regulation of gene expression is likely to be a key factor in the functional specificity of cytotrophoblasts. These data are proof of principle for cell-type specific epigenetic regulation in placenta and demonstrate that the methylation profile of placenta is mainly driven by cytotrophoblasts.Key words: cytotrophoblast purification, placental fibroblast purification, DNA methylation, epigenetics, placenta, cell type-specific methylation     

Molecular characterization of the <Emphasis Type="Italic">Arginine decarboxylase</Emphasis> gene family in rice

Arginine decarboxylase (ADC) is a key enzyme in plants that converts arginine into putrescine, an important mediator of abiotic stress tolerance. Adc genes have been isolated from a number of dicotyledonous plants but the oat and rice Adc genes are the only representatives of monocotyledonous species described thus far. Rice has a small family of Adc genes, and OsAdc1 expression has been shown to fluctuate under drought and chilling stress. We identified and characterized a second rice Adc gene (OsAdc2) which encodes a 629-amino-acid protein with a predicted molecular mass of 67 kDa. An unusual feature of the OsAdc2 gene is the presence of an intron and a short upstream open reading frame in the 5′-UTR. Sequence comparisons showed that OsAdc2 is more closely related to the oat Adc gene than to OsAdc1 or to its dicot homologs, and mRNA analysis showed that the two rice genes are also differently regulated. Whereas OsAdc1 is expressed in leaf, root and stem, OsAdc2 expression is restricted to stem tissue. Protein expression was investigated with specific antibodies against ADC1 and ADC2, corroborating the mRNA data. We discuss the expression profiles of OsAdc1 and OsAdc2 and potential functions for the two corresponding proteins.     

What might cause pain in the thyroid gland? Report of a patient with subacute thyroiditis of atypical presentation

Subacute granulomatous thyroiditis (SAT), also known as de Quervain's thyroiditis or painful subacute thyroiditis, is the commonest thyroid condition responsible for neck tenderness. Other causes of pain in the thyroid gland should be taken into consideration during differential diagnosis, especially when a patient presents with misleading or equivocal signs and symptoms. We report the case of a 39 year-old woman diagnosed as having SAT whose clinical, biochemical and radiological presentation varied significantly from the common SAT manifestation. A tentative diagnosis of SAT was made based on the presented symptoms, ultrasonography and fine-needle biopsy results. However, biochemical analysis suggested neither inflammatory process nor the presence of thyrotoxicosis. Moreover, technetium scan of the thyroid revealed normal uptake of the isotope and there was neither clinical nor ultasonographic response for corticosteroids. The patient's symptoms, despite being prescribed typical treatment, gradually deteriorated and the pain became increasingly debilitating. Eventually, the patient underwent total thyroidectomy. As a result, she has become free of symptoms, but the macroscopic picture of thyroid gland, noted during the operation, gave a suspicion of neoplastic process. Nevertheless, histological study of flow samples confirmed the tentative diagnosis of de Quervain's thyroiditis, despite all previous findings that were not suggestive of it. This report confirms the likelihood that SAT can present atypically. Additionally, it indicates that surgical treatment may be considered in patients with severe, debilitating, persistent thyroid gland pain connected with SAT clinical course.     

Microbial biofilms on facial prostheses

The composition of microbial biofilms on silicone rubber facial prostheses was investigated and compared with the microbial flora on healthy and prosthesis-covered skin. Scanning electron microscopy showed the presence of mixed bacterial and yeast biofilms on and deterioration of the surface of the prostheses. Microbial culturing confirmed the presence of yeasts and bacteria. Microbial colonization was significantly increased on prosthesis-covered skin compared to healthy skin. Candida spp. were exclusively isolated from prosthesis-covered skin and from prostheses. Biofilms from prostheses showed the least diverse band-profile in denaturing gradient gel electrophoresis (DGGE) whereas prosthesis-covered skin showed the most diverse band-profile. Bacterial diversity exceeded yeast diversity in all samples. It is concluded that occlusion of the skin by prostheses creates a favorable niche for opportunistic pathogens such as Candida spp. and Staphylococcus aureus. Biofilms on healthy skin, skin underneath the prosthesis and on the prosthesis had a comparable composition, but the numbers present differed according to the microorganism.     

Reproductive isolation between diploid and tetraploid cytotypes of Libidibia ferrea (= Caesalpinia ferrea) (Leguminosae): ecological and taxonomic implications

Polyploidy is the most common chromosomal mechanism involved in the evolution of plants. However, the emergence of polyploid individuals does not guarantee the establishment of a new lineage, and the relationship between polyploidy and reproductive biology is therefore relevant. Libidibia ferrea is a legume tree that has diploid and tetraploid populations. In this work we analyse the reproductive biology of the species to verify the degree of reproductive isolation between the two cytotypes. Observations on phenology, floral morphology, biology, and visitors, breeding system, reproductive success and reproductive isolation were made for both cytotypes in two municipalities of northeastern Brazil. Cytotypes differed for all morphometric parameters analysed, with tetraploids exhibiting higher mean values than diploids. Both cytotypes had the same effective pollinators (native bees from the genera Centris and Xylocopa, and the introduced Apis mellifera). However, since stamens of diploids and tetraploids were of different size, it is possible that spatial separation occurs when pollen of each cytotype is deposited on a bee’s body. Diploids were self-incompatible (ISI?=?0) and exhibited high fruit-set after intraploidy crossing (20?%), whereas tetraploids were self-compatible (ISI?=?0.47) and set only 3.9?% of fruits after intraploidy crossing. Both cytotypes showed low fruit- and seed-set under natural conditions, and there was no fruit-set after crosses between them. Data are discussed in relation to the establishment of polyploids, to the pattern of distribution of the species and to the taxonomic implications. The cytotypes of L. ferrea should be considered as distinct species, since they are reproductively isolated from each other.