Reduction of 1,4-quinone and ubiquinones by hydrogen atom transfer under UVA irradiation

1,4-Benzoquinone, coenzyme Q 0 and Q 10 were reacted with a series of hydrogen donors in the ESR cavity in the presence or absence of UVA irradiation. The signals of the radicals generated from the hydrogen donors or of those of the semiquinones were detected. The reaction mechanism was interpreted by a hydrogen atom transfer instead of the usual electron transfer mechanism on the basis of the redox potentials of the reactants and the Marcus theory. The hydrogen atom transfer is explained by the excited triplet state of quinones, which, on the basis of quantum mechanic calculations, may be reached even under visible light. In some cases, hydrogen atom transfer was also observed without irradiation, although to a lesser extent.     

The cell cycle-regulated protein human GTSE-1 controls DNA damage-induced apoptosis by affecting p53 function

GTSE-1 (G2 and S phase-expressed-1) protein is specifically expressed during S and G2 phases of the cell cycle. It is mainly localized to the microtubules and when overexpressed delays the G2 to M transition. Here we report that human GTSE-1 (hGTSE-1) protein can negatively regulate p53 transactivation function, protein levels, and p53-dependent apoptosis. We identified a physical interaction between the C-terminal regulatory domain of p53 and the C-terminal region of hGTSE-1 that is necessary and sufficient to down-regulate p53 activity. Furthermore, we provide evidence that hGTSE-1 is able to control p53 function in a cell cycle-dependent fashion. hGTSE-1 knock-down by small interfering RNA resulted in a S/G2-specific increase of p53 levels as well as cell sensitization to DNA damage-induced apoptosis during these phases of the cell cycle. Altogether, this work suggests a physiological role of hGTSE-1 in apoptosis control after DNA damage during S and G2 phases through regulation of p53 function.     

Ciliate–adenovirus interactions in experimental co-cultures of Euplotes octocarinatus and in wastewater environment

The aim of the present work was to study the dynamics of the interactions between human adenovirus and ciliates under both experimental and field conditions. Experimental co-cultures of the ciliated protozoan Euplotes octocarinatus and human adenovirus (HAdV) type 2 were established and virus internalization was investigated using nested PCR and direct immunofluorescence (IF). In addition, to study protozoa-virus interactions in the field, wild ciliates were isolated from active sludges of a wastewater treatment plant and analyzed for the presence of adenovirus using direct IF. In vitro experiments revealed HAdV type 2 inside Euplotes cells after 15 min of contact and its persistence until at least 35 days post infection. In addition, our results showed the adsorption of adenovirus on the surface of wild ciliates. We conclude that HAdV is taken up by ciliates, however more studies are necessary in order to better investigate the mechanisms, the infectivity of internalized virus and the protective effects of internalization against disinfection.     

Detection of Mycobacterium leprae DNA in clinical and environmental samples using serological analysis and PCR

Molecular Biology Reports - Leprosy is a chronic infectious disease caused by Mycobacterium leprae and persists as a serious public health problem in Brazil. This microorganism is inculturable,...     

Host plant distributions and climate interact to affect the predicted geographic distribution of a Neotropical termite

Species distribution models (SDMs) have been widely used in the scientific literature. The majority of SDMs use climate data or other abiotic variables to forecast the potential distribution of a species in geographic space. Biotic interactions can affect the predicted spatial distribution of a species in many ways across multiple spatial scales, and incorporating these predictors in an SDM is a current topic in the scientific literature. Constrictotermes cyphergaster is a widely distributed termite in the Neotropics. This termite species nests in plants and more frequently nests in some arboreal species. Thus, this species is an excellent model to evaluate the influence of biotic interactions in SDMs. We evaluate the influences of climate and the geographic distribution of host plants on the potential distribution of C. cyphergaster. Three correlative models (MaxEnt) were built to predict the geographic distribution of the termite: (1) climate data, (2) biotic data (i.e., the geographic distribution of host plants), and (3) climate and biotic data. The models that were generated indicate that the potential geographic distribution of C. cyphergaster is concentrated in the Cerrado and Caatinga regions. In addition, path analysis and multiple regression revealed the importance of the direct effects of biological interactions in the geographic distribution of the termite, while climate affected the distribution of the termite mainly through indirect effects by influencing the geographic distributions of host plants. The current study endorses the importance of including biological interactions in SDMs. We recommend using biotic predictors in SDM studies of insect species, mainly because insects have important environmental services and biotic interaction data can improve the macroecological studies of this group.     

Use of agroecosystem matrix habitats by mammalian carnivores (Carnivora): a global‐scale analysis

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A journey through the Amazon Middle Earth reveals Aspidoras azaghal (Siluriformes: Callichthyidae), a new species of armoured catfish from the rio Xingu basin,Brazil

Aspidoras azaghal n. sp. was discovered during a multitaxonomic scientific expedition to the remote Amazon Terra do Meio region in tributaries to the rio Xingu basin, Pará, Brazil. The new species can be promptly distinguished from its congeners by the following combination of features: (a) absence of the first dorsal-fin element; (b) parieto-supraoccipital fontanel located medially on bone; (c) absence of a longitudinal dark-brown or black stripe along flank midline; (d) ventral surface of trunk covered by clearly smaller, irregular and/or roundish platelets; (e) inner laminar expansion of infraorbital 1 well developed; (f) relatively wide frontal bone, with width equal to half of entire length; (g) absence of a thick, longitudinal conspicuous dark-brown stripe along dorsal portion of flank; and (h) poorly developed serrations on posterior margin of the pectoral-fin spine. Besides morphological evidence, the molecular analyses indicated significant differences between the new species and its congeners, with A. albater and A. raimundi as its closest species, showing 6.53% of genetic differentiation in both cases. The intraspecific molecular data revealed gene flow (peer fixation index, FST = 0.05249, P > 0.05, for the cytochrome oxidase I (COI) marker and FST = -0.01466, P > 0.05, for the control region) between specimens upstream and downstream from a 30-m height waterfall at the type-locality, which therefore represent a single population. Furthermore, it was possible to observe a unidirectional gene flow pattern, with genetic diversity increasing in the downstream direction.     

Functional architecture of higher plant photosystem II supercomplexes

Photosystem II (PSII) is a large multiprotein complex, which catalyses water splitting and plastoquinone reduction necessary to transform sunlight into chemical energy. Detailed functional and structural studies of the complex from higher plants have been hampered by the impossibility to purify it to homogeneity. In this work, homogeneous preparations ranging from a newly identified particle composed by a monomeric core and antenna proteins to the largest C₂S₂M₂ supercomplex were isolated. Characterization by biochemical methods and single particle electron microscopy allowed to relate for the first time the supramolecular organization to the protein content. A projection map of C₂S₂M₂ at 12 Å resolution was obtained, which allowed determining the location and the orientation of the antenna proteins. Comparison of the supercomplexes obtained from WT and Lhcb‐deficient plants reveals the importance of the individual subunits for the supramolecular organization. The functional implications of these findings are discussed and allow redefining previous suggestions on PSII energy transfer, assembly, photoinhibition, state transition and non‐photochemical quenching.     

An Outlook on Ovarian Cancer and Borderline Ovarian Tumors: Focus on Genomic and Proteomic Findings

Among the gynaecological malignancies, ovarian cancer is one of the neoplastic forms with the poorest prognosis and with the bad overall and disease-free survival rates than other gynaecological cancers. Ovarian tumors can be classified on the basis of the cells of origin in epithelial, stromal and germ cell tumors. Epithelial ovarian tumors display great histological heterogeneity and can be further subdivided into benign, intermediate or borderline, and invasive tumors. Several studies on ovarian tumors, have focused on the identification of both diagnostic and prognostic markers for applications in clinical practice. High-throughput technologies have accelerated the process of biomolecular study and genomic discovery; unfortunately, validity of these should be still demonstrated by extensive researches on sensibility and sensitivity of ovarian cancer novel biomarkers, determining whether gene profiling and proteomics could help differentiate between patients with metastatic ovarian cancer and primary ovarian carcinomas, and their potential impact on management. Therefore, considerable interest lies in identifying molecular and protein biomarkers and indicators to guide treatment decisions and clinical follow up. In this review, the current state of knowledge about the genoproteomic and potential clinical value of gene expression profiling in ovarian cancer and ovarian borderline tumors is discussed, focusing on three main areas: distinguishing normal ovarian tissue from ovarian cancers and borderline tumors, identifying different genotypes of ovarian tissue and identifying proteins linked to cancer or tumor development. By these targets, authors focus on the use of novel molecules, developed on the proteomics and genomics researches, as potential protein biomarkers in the management of ovarian cancer or borderline tumor, overlooking on current state of the art and on future perspectives of researches.Key Words: Ovarian cancer, borderline ovarian tumors, markers, genomics, proteomics, oncogenes.     

In vitro organogenesis from root culture segments of Bixa orellana L. (Bixaceae)

The organogenic potential of root explants derived from cultured seedlings of Bixa orellana L. (annatto) was investigated in response to different incubation conditions and either 4.44 μM 6-benzyladenine, 4.54 μM Thidiazuron, or 4.56 μM Zeatin. Explants cultured in liquid media with agitation generally showed better development of adventitious buds versus explants cultured on semi-solid media. The most adventitious buds developed from explants cultured in liquid media under a 16-h photoperiod. Use of Zeatin and Thidiazuron promoted the development of more adventitious buds than 6-benzyladenine but morphological abnormalities among regenerating shoots and plants were observed. Fewer adventitious buds developed from explants cultured in liquid media supplemented with 6-benzyladenine, but the buds gave rise to the highest percentage of morphologically normal regenerated plants. Histological analyses showed that adventitious buds originated from cell proliferation within the pericycle, opposite the protoxylem poles of the explant. Seedling root tissue is useful for in vitro propagation of B. orellana.