Responses of entomopathogenic fungi to the mutagen 4-nitroquinoline 1-oxide

Survival of entomopathogenic fungi under solar ultraviolet (UV) radiation is paramount to the success of biological control of insect pests and disease vectors. The mutagenic compound 4-nitroquinoline 1-oxide (4-NQO) is often used to mimic the biological effects of UV radiation on organisms. Therefore, we asked whether tolerance to 4-NQO could predict tolerance to UV radiation in thirty isolates of entomopathogenic fungi and one isolate of a xerophilic fungus. A dendrogram obtained from cluster analyses based on the 50 and 90 % inhibitory concentrations (IC₅₀ and IC₉₀, respectively) divided the fungal isolates into six clusters numbered consecutively based on their tolerance to 4-NQO. Cluster 6 contained species with highest tolerance to 4-NQO (IC₅₀ > 4.7 μM), including Mariannaea pruinosa, Lecanicillium aphanocladii, and Torrubiella homopterorum. Cluster 1 contained species least tolerant to 4-NQO (IC₅₀ < 0.2 μM), such as Metarhizium acridum (ARSEF 324), Tolypocladium geodes, and Metarhizium brunneum (ARSEF 7711). With few exceptions, the majority of Metarhizium species showed moderate to low tolerances (IC₅₀ between 0.4 and 0.9 μM) and were placed in cluster 2. Cluster 3 included species with moderate tolerance (IC₅₀ between 1.0 and 1.2 μM). In cluster 4 were species with moderate to high tolerance (IC₅₀ between 1.3 and 1.6 μM). Cluster 5 contained the species with high tolerance (IC₅₀ between 1.9 and 4.0 μM). The most UV tolerant isolate of M. acridum, ARSEF 324, was the least tolerant to 4-NQO. Also, L. aphanocladii, which is very susceptible to UV radiation, showed high tolerance to 4-NQO. Our results indicate that tolerance to 4-NQO does not correlate with tolerance to UV radiation. Therefore this chemical compound is not a predictor of UV tolerance in entomopathogenic fungi.     

Advances in cellular technology in the hematology field: What have we learned so far?

Despite the advances in the hematology field, blood transfusion-related iatrogenesis is still a major issue to be considered during such procedures due to blood antigenic incompatibility. This places pluripotent stem cells as a possible ally in the production of more suitable blood products. The present review article aims to provide a comprehensive summary of the state-of-theart concerning the differentiation of both embryonic stem cells and induced pluripotent stem cells to hematopoietic cell lines. Here, we review the most recently published protocols to achieve the production of blood cells for future application in hemotherapy, cancer therapy and basic research.     

Phytoplankton assemblages in a Brazilian subtropical cascading reservoir system

Variations in the structure and dynamics of a phytoplankton community were determined during two periods in 2001, along five cascading reservoirs of the Iguaçu River, Paraná State (Brazil). The vertical dynamics of the phytoplankton was related to underwater light availability and the water column-mixing regime. Correlations between physical and chemical variables and phytoplankton abundance were evaluated by Canonical Correspondence Analysis (CCA). No significant cascading effect throughout the serial reservoirs was obtained. Thus, the main factor affecting the structure of the phytoplankton assemblages of each reservoir was the hydrodynamic pattern. The instability of the water column during the winter favored the development of R-strategist species such as Aulacoseira granulata, Urosolenia longiseta and U. eriensis in most reservoirs. In the period of the highest hydraulic stability and temperature, the greatest contribution to biomass came from Cyanophyceae S-strategists such as Aphanocapsa sp.1, Anabaena planctonica and A. crassa. The phytoplanktonic associations recorded were important indicators of the environmental conditions of these reservoirs.     

Mesenchymal Stem Cells Derived from Human Exfoliated Deciduous Teeth (SHEDs) Induce Immune Modulatory Profile in Monocyte-Derived Dendritic Cells

Background

Mesenchymal stem cells have prominent immune modulatory properties, which may have clinical applications; however their major source, bone marrow, is of limited availability. On the other hand, mesenchymal stem cells derived from human exfoliated deciduous teeth (SHEDs) are readily accessible, but their immune regulatory properties have not been completely investigated. This study was designed, therefore, to evaluate the SHEDs influence on DCs differentiation, maturation, ability to activate T cells and to expand CD4⁺Foxp3⁺ T cells.

Methodology/Principal Findings

The experiments were based in cellular co-culture during differentiation and maturation of monocyte derived-DCs (moDCs), with, or not, presence of SHEDs. After co-culture with SHEDs, (moDCs) presented lower expression of BDCA-1 and CD11c, in comparison to DC cultivated without SHEDs. CD40, CD80, CD83 and CD86 levels were also decreased in mature DCs (mDCs) after co-cultivation with SHEDs. To assess the ability of SHEDs-exposed moDCs to modulate T cell responses, the former were separated from SHEDs, and co-cultured with peripheral blood lymphocytes. After 5 days, the proliferation of CD4⁺ and CD8⁺ T cells was evaluated and found to be lower than that induced by moDCs cultivated without SHEDs. In addition, an increase in the proportion of CD4⁺Foxp3⁺IL-10⁺ T cells was observed among cells stimulated by mature moDCs that were previously cultivated with SHEDs. Soluble factors released during co-cultures also showed a reduction in the pro-inflammatory cytokines (IL-2, TNF-α and IFN-γ), and an increase in the anti-inflammatory molecule IL-10.

Conclusion/Significance

This study shows that SHEDs induce an immune regulatory phenotype in moDCs cells, evidenced by changes in maturation and differentiation rates, inhibition of lymphocyte stimulation and ability to expand CD4⁺Foxp3⁺ T cells. Further characterization and validation of this phenomenon could support the use of SHEDs, directly or indirectly for immune modulation in the clinical practice.     

The Xenon Test Chamber Q-SUN® for testing realistic tolerances of fungi exposed to simulated full spectrum solar radiation

The low survival of insect-pathogenic fungi when used for insect control in agriculture is mainly due to the deleterious effects of ultraviolet radiation and heat from solar irradiation. In this study, conidia of 15 species of entomopathogenic fungi were exposed to simulated full-spectrum solar radiation emitted by a Xenon Test Chamber Q-SUN XE-3-HC 340S (Q-LAB^® Corporation, Westlake, OH, USA), which very closely simulates full-spectrum solar radiation. A dendrogram obtained from cluster analyses, based on lethal time 50 % and 90 % calculated by Probit analyses, separated the fungi into three clusters: cluster 3 contains species with highest tolerance to simulated full-spectrum solar radiation, included Metarhizium acridum, Cladosporium herbarum, and Trichothecium roseum with LT₅₀ > 200 min irradiation. Cluster 2 contains eight species with moderate UV tolerance: Aschersonia aleyrodis, Isaria fumosorosea, Mariannaea pruinosa, Metarhizium anisopliae, Metarhizium brunneum, Metarhizium robertsii, Simplicillium lanosoniveum, and Torrubiella homopterorum with LT₅₀ between 120 and 150 min irradiation. The four species in cluster 1 had the lowest UV tolerance: Lecanicillium aphanocladii, Beauveria bassiana, Tolypocladium cylindrosporum, and Tolypocladium inflatum with LT₅₀ < 120 min irradiation. The QSUN Xenon Test Chamber XE3 is often used by the pharmaceutical and automotive industry to test light stability and weathering, respectively, but it was never used to evaluate fungal tolerance to full-spectrum solar radiation before. We conclude that the equipment provided an excellent tool for testing realistic tolerances of fungi to full-spectrum solar radiation of microbial agents for insect biological control in agriculture.     

A bird's-eye view: Evaluating drone imagery for the detection and monitoring of endangered and invasive day geckos

Species monitoring can be strongly limited by terrain accessibility, impeding our understanding of species ecology and thus challenging their conservation. This is particularly true for species living in the canopy, on cliffs or in dense vegetation. Remote sensing imagery may fill this gap by offering a cost-effective monitoring approach allowing to improve species detection in inaccessible areas. We investigated the applicability of drone-based monitoring for a Critically Endangered insular gecko (Phelsuma inexpectata) and two invasive alien gecko species representing a risk for the former (P. grandis and P. laticauda). We determined the approach distance before inducing behavioural response caused by the drone's presence. All three study species showed no escape behaviour to the drone's presence until very close distances (mean distance for P. inexpectata: 33.8 cm; P. grandis: 21.9 cm; P. laticauda: 26.4 cm). We then performed horizontal and vertical approaches with the drone, taking photos every meter starting at 10 m away from the canopy edge to determine an optimal distance for detection while ensuring species-level identification. We examined a total of 328 photos. We found a bimodality in the number of detected geckos for two species, with different individuals recorded between short and intermediate distances. Therefore, we recommend taking photos at two distances of 2–2.5 and 5 m away from the canopy, ideally facing away from the sun and in low wind conditions. We encourage the application of our methodology for Phelsuma spp., but also for other species of similar size and ecology to improve detection in inaccessible areas.     

Assessment of In Vivo and In Vitro Genotoxicity of Glibenclamide in Eukaryotic Cells

Glibenclamide is an oral hypoglycemic drug commonly prescribed for the treatment of type 2 diabetes mellitus, whose anti-tumor activity has been recently described in several human cancer cells. The mutagenic potential of such an antidiabetic drug and its recombinogenic activity in eukaryotic cells were evaluated, the latter for the first time. The mutagenic potential of glibenclamide in therapeutically plasma (0.6 μM) and higher concentrations (10 μM, 100 μM, 240 μM and 480 μM) was assessed by the in vitro mammalian cell micronucleus test in human lymphocytes. Since the loss of heterozygosity arising from allelic recombination is an important biologically significant consequence of oxidative damage, the glibenclamide recombinogenic activity at 1 μM, 10 μM and 100 μM concentrations was evaluated by the in vivo homozygotization assay. Glibenclamide failed to alter the frequency of micronuclei between 0.6 μM and 480 μM concentrations and the cytokinesis block proliferation index between 0.6 μM and 240 μM concentrations. On the other hand, glibenclamide changed the cell-proliferation kinetics when used at 480 μM. In the homozygotization assay, the homozygotization indices for the analyzed markers were lower than 2.0 and demonstrated the lack of recombinogenic activity of glibenclamide. Data in the current study demonstrate that glibenclamide, in current experimental conditions, is devoid of significant genotoxic effects. This fact encourages further investigations on the use of this antidiabetic agent as a chemotherapeutic drug.     

Breaking dormancy of <Emphasis Type="Italic">Stylosanthes humilis</Emphasis> seeds with low pH solutions

An acidic condition (low pH) of the germination media promoted dormancy breakage of scarified seeds of Townsville stylo (Stylosanthes humilis H.B.K.), an annual tropical forage legume, whether produced by either an unbuffered (HCl-KOH) or a buffered (phthalate, McIlvaine) medium. Except for aminooxyacetic acid, all ethylene biosynthesis inhibitors tested and supplied with the low pH solutions decreased germination to variable extents. Low pH-stimulated dormant seeds produced ethylene 4-fold as much than untreated seeds. Production of ethylene by seeds treated with high pH solutions, which did not affect their dormant state, was also very low.