Leaf traits interact with management and water table to modulate ecosystem properties in fen peatlands

Plant and Soil - Trade-offs between slow and fast nutrient turnover rates among plants may affect soil properties and biomass production. We examined how plant traits interact with abiotic...     

Megabase Length Hypermutation Accompanies Human Structural Variation at 17p11.2

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Explant type and natural ventilation systems influence growth and content of carvacrol and thymol of Lippia gracilis Schauer

The objective of this study was to evaluate the effects of different natural ventilation systems and explant types on the growth and volatile compound content of Lippia gracilis cultured in vitro. The treatments consisted of four membrane systems (without membrane, with one, two, and four porous membranes) and two explant types (nodal segments with and without a pair of leaves). The evaluation of growth, photosynthetic pigments and chemical analysis of the volatile fraction were performed at 35 days of cultivation in half strength MS basal medium. Natural ventilation systems significantly influenced the in vitro growth and volatile fraction of L. gracilis. Explants with a pair of leaves obtained the best experimental responses. The natural ventilation system with four membranes provided the best growth parameters and leaf area response of L. gracilis explants with leaves. The photosynthetic pigments decreased with an increase in the number of porous membranes in the culture flask. Variations in the number, content, and profile of volatile compounds under the influence of natural ventilation systems were observed. Major constituents such as ρ-cymene, γ-terpinene, thymol, carvacrol, and E-caryophyllene, regardless of experimental conditions, were identified. The highest carvacrol and thymol contents were observed in plantlets grown in culture flasks with four porous membranes. To maximize the content of carvacrol and thymol from the in vitro culture of L. gracilis, explants with a pair of leaves and four porous membranes in culture flasks are recommended for use.

     

Differential temporal beta‐diversity patterns of native and non‐native arthropod species in a fragmented native forest landscape

An important factor that hinders the management of non‐native species is a general lack of information regarding the biogeography of non‐natives, and, in particular, their rates of turnover. Here, we address this research gap by analysing differences in temporal beta‐diversity (using both pairwise and multiple‐time dissimilarity metrics) between native and non‐native species, using a novel time‐series dataset of arthropods sampled in native forest fragments in the Azores. We use a null model approach to determine whether temporal beta‐diversity was due to deterministic processes or stochastic colonisation and extinction events, and linear modelling selection to assess the factors driving variation in temporal beta‐diversity between plots. In accordance with our predictions, we found that the temporal beta‐diversity was much greater for non‐native species than for native species, and the null model analyses indicated that the turnover of non‐native species was due to stochastic events. No predictor variables were found to explain the turnover of native or non‐native species. We attribute the greater turnover of non‐native species to source‐sink processes and the close proximity of anthropogenic habitats to the fragmented native forest plots sampled in our study. Thus, our findings point to ways in which the study of turnover can be adapted for future applications in habitat island systems. The implications of this for biodiversity conservation and management are significant. The high rate of stochastic turnover of non‐native species indicates that attempts to simply reduce the populations of non‐native species in situ within native habitats may not be successful. A more efficient management strategy would be to interrupt source‐sink dynamics by improving the harsh boundaries between native and adjacent anthropogenic habitats.     

Titanium with nanotopography induces osteoblast differentiation through regulation of integrin αV

Topographical modifications of titanium (Ti) at the nanoscale level generate surfaces that regulate several signaling pathways and cellular functions, which may affect the process of osseointegration. Here, we investigated the participation of integrin αV in the osteogenic capacity of Ti with nanotopography. Machined titanium discs (untreated) were submitted to treatment with H₂SO₄/H₂O₂ to produce the nanotopography (nanostructured). First, the greater osteogenic capacity of the nanotopography that increased osteoblast differentiation of mesenchymal stem cells compared with untreated topography was shown. Also, the nanostructured surface increased (regulation ≥ 1.9-fold) the gene expression of 6 integrins from a custom array plate utilized to evaluate the gene expression of 84 genes correlated with cell adhesion signaling pathway, including integrin αV, which is involved in osteoblast differentiation. By silencing integrin αV in MC3T3-E1 cells cultured on nanotopography, the impairment of osteoblast differentiation induced by this surface was observed. In conclusion, it was shown that nanotopography regulates the expression of several components of the cell adhesion signaling pathway and its higher osteogenic potential is, at least in part, due to its ability to upregulate the expression of integrin αV. Together with previous data that showed the participation of integrins α1, β1, and β3 in the nanotopography osseoinduction activity, we have uncovered the pivotal role of this family of membrane receptors in the osteogenic potential of this surface.     

Double-antigen sandwich ELISA based on chimeric antigens for detection of antibodies to Trypanosoma cruzi in human sera

BackgroundEnzyme-linked immunosorbent assays (ELISA) are generally the chosen test for Chagas disease (CD) diagnosis; however, its performance depends on the antigen preparation adsorbed to the solid phase, which may lead to false-positive results and cross-reactions. The use of chimeric recombinant antigens can overcome this limitation. Four chimeric antigens from Trypanosoma cruzi (IBMP-8.1, IBMP-8.2, IBMP-8.3 and IBMP-8.4) were developed and evaluated in phase I, II and III studies using indirect ELISA as diagnostic platform. However, peroxidase-labeled secondary anti-human IgG antibody, which is employed in indirect ELISAs, limits its use for the detection of species-specific and class-specific antibodies. To overcome this limitation, peroxidase-labeled antigens can be utilized, diagnosing both acute or chronic infection, in a species and immunoglobulin class-independent manner, through the use of a double-antigen sandwich ELISA (DAgS-ELISA). We aimed to evaluate and validate the diagnostic performance of the chimeric antigens IBMP-8.1, IBMP-8.2, IBMP-8.3 and IBMP-8.4 in the DAgS-ELISA platform.Methodology/Principal findingsDAgS-ELISA was optimized by checkerboard titration. In phase I study, 207 positive and 205 negative samples were evaluated. Cross-reactivity to other infections was also assessed using 68 samples. The selected conditions for the tests utilized 25 ng of antigen per well and the conjugate diluted at 1:2,000 for all molecules. In the phase I study, the areas under the curve of IBMP-8.1, IBMP-8.2, IBMP-8.3 and IBMP-8.4 were 98.7%, 99.5%, 98.6% and 98.8%, respectively. Among the positive samples, IBMP-8.1 antigen classified 53 (25.6%) as false negative, IBMP-8.2, 27 (13%), IBMP-8.3, 24 (11.6%) and IBMP-8.4, 43 (20.8%), giving sensitivities of 74.4%, 87%, 88.4% and 79.2%, respectively. The only antigen that did not reach 100% specificity was IBMP-8.3, with 96.6%. IBMP-8.3 was also the only molecule to show cross-reactivity with HTLV.Conclusions/SignificanceDAgS-ELISA is a promising tool for immunodiagnosis, and despite the high AUC values, the performance of this assay was different from the values obtained by our group when using these antigens in the indirect ELISA, for this reason, improvements are being considered to increase the sensitivity of the DAgS-ELISA.     

Redox imbalance induces remodeling of glucose metabolism in Rhipicephalus microplus embryonic cell line

Carbohydrate metabolism not only functions in supplying cellular energy but also has an important role in maintaining physiological homeostasis and in preventing oxidative damage caused by reactive oxygen species. Previously, we showed that arthropod embryonic cell lines have high tolerance to H₂O₂ exposure. Here, we describe that Rhipicephalus microplus tick embryonic cell line (BME26) employs an adaptive glucose metabolism mechanism that confers tolerance to hydrogen peroxide at concentrations too high for other organisms. This adaptive mechanism sustained by glucose metabolism remodeling promotes cell survival and redox balance in BME26 cell line after millimolar H₂O₂ exposure. The present work shows that this tick cell line could tolerate high H₂O₂ concentrations by initiating a carbohydrate-related adaptive response. We demonstrate that gluconeogenesis was induced as a compensation strategy that involved, among other molecules, the metabolic enzymes NADP-ICDH, G6PDH, and PEPCK. We also found that this phenomenon was coupled to glycogen accumulation and glucose uptake, supporting the pentose phosphate pathway to sustain NADPH production and leading to cell survival and proliferation. Our findings suggest that the described response is not atypical, being also observed in cancer cells, which highlights the importance of this model to all proliferative cells. We propose that these results will be useful in generating basic biological information to support the development of new strategies for disease treatment and parasite control.     

Defective hematopoietic differentiation of immune aplastic anemia patient-derived iPSCs

In acquired immune aplastic anemia (AA), pathogenic cytotoxic Th1 cells are activated and expanded, driving an immune response against the hematopoietic stem and progenitor cells (HSPCs) that provokes cell depletion and causes bone marrow failure. However, additional HSPC defects may contribute to hematopoietic failure, reflecting on disease outcomes and response to immunosuppression. Here we derived induced pluripotent stem cells (iPSCs) from peripheral blood (PB) erythroblasts obtained from patients diagnosed with immune AA using non-integrating plasmids to model the disease. Erythroblasts were harvested after hematologic response to immunosuppression was achieved. Patients were screened for germline pathogenic variants in bone marrow failure-related genes and no variant was identified. Reprogramming was equally successful for erythroblasts collected from the three immune AA patients and the three healthy subjects. However, the hematopoietic differentiation potential of AA-iPSCs was significantly reduced both quantitatively and qualitatively as compared to healthy-iPSCs, reliably recapitulating disease: differentiation appeared to be more severely affected in cells from the two patients with partial response as compared to the one patient with complete response. Telomere elongation and the telomerase machinery were preserved during reprogramming and differentiation in all AA-iPSCs. Our results indicate that iPSCs are a reliable platform to model immune AA and recapitulate clinical phenotypes. We propose that the immune attack may cause specific epigenetic changes in the HSPCs that limit adequate proliferation and differentiation.Subject terms: Anaemia, Induced pluripotent stem cells     

Rice Resistance to Brown Spot Mediated by Nitrogen and Potassium

This study was undertaken to investigate the effects of both nitrogen (N) and potassium (K) rates on rice resistance to brown spot, caused by the fungus Bipolaris oryzae. Rice plants (cultivar ‘Metica 1’) were grown in soil corrected with 0, 25, 50, 75 and 100 mg of N / kg (as NH₄NO₃) of soil as well as with 25, 50, 75, 125 and 150 mg of K / kg (as KCl) of soil. Thirty‐three‐day‐old plants were inoculated with a suspension of Bipolaris oryzae conidia and the incubation period (IP), number of lesions (NL) per cm² of leaf area and disease severity was evaluated. Disease severity was scored at 24, 48, 72, 96, 120 and 144 h after inoculation and data were used to obtain the area under brown spot progress curve (AUBSPC). Soil plant analysis development (SPAD) index, plant dry weight and concentration of N and K in leaf tissues were also determined for both non‐inoculated (NI) and inoculated (IN) plants. Concentration of N in leaf tissue increased as the N rates in the soil increased. Concentration of K in leaf tissue increased sharply as the K rates in the soil increased for both NI and IN plants. Concentration of K in leaf tissue was not affected by N rates. The IP increased as the N rates increased, but was somewhat less impacted by increasing K rates. The NL decreased as the N rates increased. The NL dramatically declined at the highest K rates. The AUBSPC dramatically declined as the N and K rates in the soil increased. SPAD index values increased as the N and K rates in the soil increased for both NI and IN plants. Plant dry weight increased as the N and K rates in the soil increased for both NI and IN plants. Results from this study suggest that combining high N and K rates may contribute to reducing the intensity of brown spot in rice while improving plant development.     

13C isotopomer analysis of glutamate by J-resolved heteronuclear single quantum coherence spectroscopy

13C NMR isotopomer analysis is a powerful method for measuring metabolic fluxes through pathways intersecting in the tricarboxylic acid cycle. However, the inherent insensitivity of 13C NMR spectroscopy makes application of isotopomer analysis to small tissue samples (mouse tissue, human biopsies, or cells grown in tissue culture) problematic. (1)H NMR is intrinsically more sensitive than 13C NMR and can potentially supply the same information via indirect detection of 13C providing that isotopomer information can be preserved. We report here the use of J-resolved HSQC (J-HSQC) for 13C isotopomer analysis of tissue samples. We show that J-HSQC reports isotopomer multiplet patterns identical to those reported by direct 13C detection but with improved sensitivity.