Early dystrophin disruption in the pathogenesis of experimental chronic Chagas cardiomyopathy

Chronic Chagas cardiomyopathy evolves over a long period of time after initial infection by Trypanosoma cruzi. Similarly, a cardiomyopathy appears later in life in muscular dystrophies. This study tested the hypothesis that dystrophin levels are decreased in the early stage of T. cruzi-infected mice that precedes the later development of a cardiomyopathy. CD1 mice were infected with T. cruzi (Brazil strain), killed at 30 and 100 days post infection (dpi), and the intensity of inflammation, percentage of interstitial fibrosis, and dystrophin levels evaluated. Echocardiography and magnetic resonance imaging data were evaluated from 15 to 100 dpi. At 30 dpi an intense acute myocarditis with ruptured or intact intracellular parasite nests was observed. At 100 dpi a mild chronic fibrosing myocarditis was detected without parasites in the myocardium. Dystrophin was focally reduced or completely lost in cardiomyocytes at 30 dpi, with the reduction maintained up to 100 dpi. Concurrently, ejection fraction was reduced and the right ventricle was dilated. These findings support the hypothesis that the initial parasitic infection-induced myocardial dystrophin reduction/loss, maintained over time, might be essential to the late development of a cardiomyopathy in mice.     

Ants as Indicators of the Success of Rehabilitation Efforts in Deposits of Gold Mining Tailings

The evaluation of the success of restoration efforts is an essential step for environmental monitoring programs, providing reliable and intricate information on the response of biotic and abiotic elements of ecosystem following the restoration programs adopted. The aim of this study was to evaluate the efficacy of different rehabilitation efforts after gold mining activities using ants as bioindicators. We tested the following hypotheses: (1) the ant species richness and composition vary with the technique of revegetation and (2) the number of epigaeic and hypogaeic ant species increases with resources. We selected four tailing dumps from gold mining, one spontaneously revegetated (“Natural”) and the other three areas with different rehabilitation techniques, namely: Grassy 2005—rehabilitation with grasses in 2005; Grassy 2006—rehabilitation with grasses in 2006, and Shrubby 2004—rehabilitation with grasses, herbaceous, and shrubs in 2004. Ants were sampled using epigaeic and hypogaeic pitfall traps. Species accumulation curves show that the “Natural” area has a higher number of species. We found differences in species composition of epigaeic and hypogaeic ants among the different areas sampled. We conclude that Camponotus fastigatus can be taken as a good indicator of environmental rehabilitation in areas impacted by mining activities. Moreover, Ectatomma edentatum, Dorymyrmex brunneus, Crematogaster evallans, and Solenopsis invicta can also indicate that the rehabilitation process is not yet completed.     

A brain tumor molecular imaging strategy using a new triple-modality MRI-photoacoustic-Raman nanoparticle

The difficulty in delineating brain tumor margins is a major obstacle in the path toward better outcomes for patients with brain tumors. Current imaging methods are often limited by inadequate sensitivity, specificity and spatial resolution. Here we show that a unique triple-modality magnetic resonance imaging-photoacoustic imaging-Raman imaging nanoparticle (termed here MPR nanoparticle) can accurately help delineate the margins of brain tumors in living mice both preoperatively and intraoperatively. The MPRs were detected by all three modalities with at least a picomolar sensitivity both in vitro and in living mice. Intravenous injection of MPRs into glioblastoma-bearing mice led to MPR accumulation and retention by the tumors, with no MPR accumulation in the surrounding healthy tissue, allowing for a noninvasive tumor delineation using all three modalities through the intact skull. Raman imaging allowed for guidance of intraoperative tumor resection, and a histological correlation validated that Raman imaging was accurately delineating the brain tumor margins. This new triple-modality-nanoparticle approach has promise for enabling more accurate brain tumor imaging and resection.     

Reproductive isolation in the saltans group of Drosophila. I. The saltans subgroup

In order to study isolation within the salians subgroup, pair mating crosses involving its 7 species were performed. The results of testing different interspecific combinations varied from complete isolation at the insemination level to the production of fertile hybrids. Some isolation indices are proposed: Ii (isolation index at the insemination level), Fi (isolation index at the fertilization level), Ti (total isolation index), and Ai (average isolation index). A schema of the biological relationships on the basis of the isolation degree is also presented for the 7 species of the subgroup.Part of this study was included in the thesis submitted for the PH.D. degree at the University of São Paulo and was performed during the tenure of a fellowship supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo.     

Influence of amino acid and peptide counterions on the conformation of DNA

We describe fibre diffraction studies on the interaction of DNA with different amino acids and peptides. The B form of DNA, with ten base-pairs per turn, is always found at high levels of humidity. We suggest that this pitch is observed because the DNA molecules are maintained in a straight position. In solution, the DNA molecules are bent and may have a larger pitch. The A form of DNA is never found upon dehydration. Instead, the B form may be either stabilized by the counterions or altered so that the number of base-pairs per helical turn decreases upon dehydration. Alteration is favoured either by small counterions that have a single charge or by large basic polypeptides and proteins. Stabilization is favoured by small counterions that have several charged groups. A third type of behaviour is found with some amino acids that contain hydrophobic groups, which destabilize the secondary structure of DNA, probably due to a modification of its intramolecular interactions. We have not detected any specific effect of amino acid side-chains, although the amino acid sequence has a clear influence on the interaction. We think that these observations are of interest in the pursuit of more detailed crystallographic studies on protein-DNA interactions.     

Root morphology,gas exchange and chlorophyll fluorescence of coffee cultivars and progenies are altered by Meloidogyne paranaensis infestation and water deficit

Climate change greatly influences coffee production, especially in areas infested with plant-parasitic nematodes. In this study, coffee genotypes showed differences in their morphological and physiological characteristics when subjected to a water deficit and parasitism by Meloidogyne paranaensis. The cultivar IPR 100 had the largest superficial and volumetric root system area, even when parasitized. The two progenies (MG 0179-1 and MG 0179-3) and the cultivar Catuaí IAC 62 had a similar surface area (p < .05) when parasitized. However, the root surface area and volume of MG 0179-3 increased by 96% and 400%, respectively, when parasitized by M. paranaensis. On the other hand, Catuaí IAC 62 had a 31% reduction in root surface area. Catuai 62 and IPR 100 showed higher sensitivity to drought when parasitized because of the increased photochemical sensitivity and reduction in photochemical quenching. In MG 0179-1 and MG 0179-3, an increase in non-photochemical quenching occurred in response to stress, indicating that these progenies use a photochemical response to protect photosystem II. In this work, MG 0179-3, which is resistant to M. paranaensis, was remarkable because, interestingly, the infestation caused an increase in its root surface area. In addition, MG 0179-3 had relatively good photochemical performance under water deficit and M. paranaensis parasitism.     

Evaluation of Chalcone Derivatives as Photosynthesis and Plant Growth Inhibitors

We report the evaluation of chalcone derivatives as photosystem II (PSII) and plant growth inhibitors. Chalcone derivatives were evaluated as PSII inhibitors through Chl a fluorescence measurement. (E)-Chalcone ( 6a ) and (E)-3-(4-bromophenyl)-1-(4-fluorophenyl)prop-2-en-1-one ( 6j ) showed the best results, reducing the performance index on absorption basis parameter (PI_abs) by 70 %. Additionally, the decrease of TR₀/RC and ET₀/RC parameters indicates that the chalcone derivatives limited the number of active PSII reaction centers and the amount of trapped energy within them. Compounds 6a and 6j both act as post-emergent herbicides at 50 μM, reducing the root biomass of the Ipomoea grandifolia weed by 72 % and 83 %, respectively, corroborating the fluorescence results. The selectivity against weeds as compared to valuable crops by compounds 6a and 6j were evaluated employing Zea mays and Phaseolus vulgaris plants. In these, our newly synthesized compounds showed no effects on biomass accumulation of roots and aerial parts when compared to the control, providing valuable evidence for the role of these compounds as selective inhibitors of the growth of undesired weeds.