Infection increases activity via Toll dependent and independent mechanisms in Drosophila melanogaster.

Host behavioural changes are among the most apparent effects of infection. 'Sickness behaviour' can involve a variety of symptoms, including anorexia, depression, and changed activity levels. Here, using a real-time tracking and behavioural profiling platform, we show that in Drosophila melanogaster, several systemic bacterial infections cause significant increases in physical activity, and that the extent of this activity increase is a predictor of survival time in some lethal infections. Using multiple bacteria and D. melanogaster immune and activity mutants, we show that increased activity is driven by at least two different mechanisms. Increased activity after infection with Micrococcus luteus, a Gram-positive bacterium rapidly cleared by the immune response, strictly requires the Toll ligand spätzle. In contrast, increased activity after infection with Francisella novicida, a Gram-negative bacterium that cannot be cleared by the immune response, is entirely independent of both Toll and the parallel IMD pathway. The existence of multiple signalling mechanisms by which bacterial infections drive increases in physical activity implies that this effect may be an important aspect of the host response.

Bacterial Toxin-Triggered Release of Antibiotics from Capsosomes Protects a Fly Model from Lethal Methicillin-Resistant Staphylococcus aureus (MRSA) Infection.

Antibiotic resistance is a severe global health threat and hence demands rapid action to develop novel therapies, including microscale drug delivery systems. Herein, a hierarchical microparticle system is developed to achieve bacteria-activated single- and dual-antibiotic drug delivery for preventing methicillin-resistant Staphylococcus aureus (MRSA) bacterial infections. The designed system is based on a capsosome structure, which consists of a mesoporous silica microparticle coated in alternating layers of oppositely charged polymers and antibiotic-loaded liposomes. The capsosomes are engineered and shown to release their drug payloads in the presence of MRSA toxins controlled by the Agr quorum sensing system. MRSA-activated single drug delivery of vancomycin and synergistic dual delivery of vancomycin together with an antibacterial peptide successfully kills MRSA in vitro. The capability of capsosomes to selectively deliver their cargo in the presence of bacteria, producing a bactericidal effect to protect the host organism, is confirmed in vivo using a Drosophila melanogaster MRSA infection model. Thus, the capsosomes serve as a versatile multidrug, subcompartmentalized microparticle system for preventing antibiotic-resistant bacterial infections, with potential applications to protect wounds or medical device implants from infections.

The Influence of Environmental Features on the Morphometric Variation in Mauritia flexuosa L.f. Fruits and Seeds.

The environmental heterogeneity may reflect the different morphological and phenotypic traits of individuals belonging to a single species. We used 14 morphological traits of Mauritia flexuosa L.f. to understanding the relation between environment and phenotypic traits. Twenty-five fruits were collected from each of the 10 individuals sampled in each study site: Chapada dos Guimarães (CG), Vila Bela da Santíssima Trindade (VB), and Alta Floresta (AF). We analyzed the genetic divergence, using the standardized Euclidean distance, the sequential method of Tocher, unweighted pair group method with arithmetic mean (UPGMA), and the projection of the distances onto 2D plane, and calculated the relative importance of the traits evaluated. The analysis showed the partition of individuals into three main groups: Two groups comprising the majority of individuals. Fresh fruit weight, pulp rate, fresh pulp weight, and moisture rate were the traits that most helped explaining the difference between materials. The results shown in the current study evidenced the influence of these three different environments on the biometric traits of M. flexuosa. Such influence has led to the formation of Alta Floresta and Vila Bela da Santíssima Trindade individuals in different groups, whereas the Chapada dos Guimarães individuals were able to permeate the two other groups, although they showed stronger tendency to group with individuals from Vila Bela da Santíssima Trindade.

Origins of Metabolic Pathology in Francisella-Infected Drosophila.

The origins and causes of infection pathologies are often not understood. Despite this, the study of infection and immunity relies heavily on the ability to discern between potential sources of pathology. Work in the fruit fly has supported the assumption that mortality resulting from bacterial invasion is largely due to direct host-pathogen interactions, as lower pathogen loads are often associated with reduced pathology, and bacterial load upon death is predictable. However, the mechanisms through which these interactions bring about host death are complex. Here we show that infection with the bacterium Francisella novicida leads to metabolic dysregulation and, using treatment with a bacteriostatic antibiotic, we show that this pathology is the result of direct interaction between host and pathogen. We show that mutants of the immune deficiency immune pathway fail to exhibit similar metabolic dysregulation, supporting the idea that the reallocation of resources for immune-related activities contributes to metabolic dysregulation. Targeted investigation into the cross-talk between immune and metabolic pathways has the potential to illuminate some of this interaction.

The microRNA-306/abrupt regulatory axis controls wing and haltere growth in Drosophila.

Growth control relies on extrinsic and intrinsic mechanisms that regulate and coordinate the size and pattern of organisms. This control is crucial for a homeostatic development and healthy physiology. The gene networks acting in this process are large and complex: factors involved in growth control are also important in diverse biological processes and these networks include multiple regulators that interact and respond to intra- and extra-cellular inputs that may ultimately converge in the control of the cell cycle. In this work we have studied the function of the Drosophila abrupt gene, coding for a BTB-ZF protein and previously reported to be required for wing vein pattern, in the control of haltere and wing growth. We have found that inactivation of abrupt reduces the size of the wing and haltere. We also found that the microRNA miR-306 controls abrupt expression and that miR-306 and abrupt genetically interact to control wing size. Moreover, the reduced appendage size due to abrupt inactivation is rescued by overexpression of Cyclin-E and by inactivation of dacapo. These findings define a miR-306-abrupt regulatory axis that controls wing and haltere size, whereby miR-306 maintains appropriate levels of abrupt expression which, in turn, regulates the cell cycle. Thus, our results uncover a novel function of abrupt in the regulation of the size of Drosophila appendages during development and contribute to the understanding of the coordination between growth and pattern as well as to the understanding of abrupt oncogenic function in flies.

Cyanobacteria as regulators of methylmercury production in periphyton.

Biotic mercury (Hg) methylation appears to depend on factors such as microbial activity and the concentration and bioavailability of Hg2+ to the Hg-methylating organisms. Recently, the presence of cyanobacteria has been linked with high methylmercury (MeHg) concentrations. The aim of this work was to test MeHg production in microcosms, in relation to the amount of periphytic cyanobacteria, dissolved organic matter (DOM) and phosphorus concentrations, as well as periphytic primary production rates. Water and periphyton samples were collected for cultivation and isolation of cyanobacteria from the Guaporé River floodplain, Brazil. We cultivated the periphyton in microcosms with different concentrations of cyanobacteria, total phosphorus and DOM. The highest net MeHg production (6.8 to 24.6% of added Hg d-1) occurred in the microcosm with added cyanobacteria, followed by microcosms with added phosphorus (6.1 to 11.4%) and added DOM (6.4 to 9.1%). Positive correlations were found between MeHg production, addition of cyanobacteria, phosphorus and DOM and periphytic primary productivity. Our results bring the first direct experimental evidence of the relevance of cyanobacteria and primary production as regulators of MeHg production in periphyton. These findings have numerous implications for the management of natural and engineered wetlands.

α-actinin accounts for the bioactivity of actin preparations in inducing STAT target genes in Drosophila melanogaster.

Damage-associated molecular patterns (DAMPs) are molecules exposed or released by dead cells that trigger or modulate immunity and tissue repair. In vertebrates, the cytoskeletal component F-actin is a DAMP specifically recognised by DNGR-1, an innate immune receptor. Previously we suggested that actin is also a DAMP in Drosophila melanogaster by inducing STAT-dependent genes (Srinivasan et al., 2016). Here, we revise that conclusion and report that α-actinin is far more potent than actin at inducing the same STAT response and can be found in trace amounts in actin preparations. Recombinant expression of actin or α-actinin in bacteria demonstrated that only α-actinin could drive the expression of STAT target genes in Drosophila. The response to injected α-actinin required the same signalling cascade that we had identified in our previous work using actin preparations. Taken together, these data indicate that α-actinin rather than actin drives STAT activation when injected into Drosophila.

Rivers shape population genetic structure in Mauritia flexuosa (Arecaceae).

The Mauritia flexuosa L.f. palm is known as the "tree of life" given its importance as fundamental food and construction resources for humans. The species is broadly distributed in wet habitats of Amazonia and dry habitats of the Amazon and Orinoco river basins and in the Cerrado savanna. We collected 179 individuals from eight different localities throughout these habitats and used microsatellites to characterize their population structure and patterns of gene flow. Overall, we found high genetic variation, except in one savanna locality. Gene flow between populations is largely congruent with river basins and the direction of water flow within and among them, suggesting their importance for seed dispersal. Further, rivers have had a higher frequency of human settlements than forested sites, contributing to population diversity and structure through increased human use and consumption of M. flexuosa along rivers. Gene flow patterns revealed that migrants are sourced primarily from within the same river basin, such as those from Madeira and Tapajós basins. Our work suggests that rivers and their inhabitants are a critical element of the landscape in Amazonia and have impacted the dispersal and subsequent distribution of tropical palm species, as shown by the patterns of genetic variation in M. flexuosa.

Epigenetic and non-epigenetic functions of the RYBP protein in development and disease.

Over the last decades significant advances have been made in our understanding of the molecular mechanisms controlling organismal development. Among these mechanisms the knowledge gained on the roles played by epigenetic regulation of gene expression is extensive. Epigenetic control of transcription requires the function of protein complexes whose specific biochemical activities, such as histone mono-ubiquitylation, affect chromatin compaction and, consequently activation or repression of gene expression. Complexes composed of Polycomb Group (PcG) proteins promote transcriptional silencing while those containing trithorax group (trxG) proteins promote transcriptional activation. However, other epigenetic protein factors, such as RYBP, have the ability to interact with both PcG and trxG and thus putatively participate in the reversibility of chromatin compaction, essential to respond to developmental cues and stress signals. This review discusses the developmental and mechanistic functions of RYBP, a ubiquitin binding protein, in epigenetic control mediated by the PcG/trxG proteins to control transcription. Recent experimental evidence indicates that proteins regulating chromatin compaction also participate in other molecular mechanisms controlling development, such as cell death. This review also discusses the role of RYBP in apoptosis through non-epigenetic mechanisms as well as recent investigations linking the role of RYBP to apoptosis and cancer.

Seasonal changes in peryphytic microbial metabolism determining mercury methylation in a tropical wetland.

Mercury (Hg) methylation, a key process in the biogeochemical cycle of Hg, is mainly attributed to sulfate-reducing bacteria and methanogenic Archaea. However, environmental regulation by these groups has not yet been ascertained in tropical environments, especially in respect to the seasonal flood flooding. This work evaluated the variation of net methylmercury production potential in relation to biological characteristics of the periphyton, environmental factors, and flood pulse seasons. Our results indicate that there is a seasonal change between metabolic groups as main Hg methylators, sulfate-reducing bacteria in the dry season and methanogenic Archaea in the flood season. In addition, there was a positive relationship between dissolved organic carbon (DOC), phosphorus, cyanobacteria biovolume, and periphytic Hg methylation potential. These results shed a new light on MeHg production plasticity, mediated by landscape and flood pulses in tropical wetlands, as well as on ecological relationships within the periphyton.

Drosophila SCE/dRING E3-ligase inhibits apoptosis in a Dp53 dependent manner.

The Polycomb group (PcG) of proteins control developmental gene silencing and are highly conserved between flies and mammals. PcG proteins function by controlling post-translational modification of histones, such as ubiquitylation, which impacts chromatin compaction and thus gene transcription. Changes in PcG cellular levels have drastic effects on organismal development and are involved in the generation of human pathologies such as cancer. However, the mechanisms controlling their levels of expression and their physiological effects are only partially understood. In this work we describe the effects of modulating levels of SCE/dRING, a conserved E3 ubiquitin ligase and member of the PcG known to mono-ubiquitylate histone H2A. We find that inactivation of Sce induces apoptosis, an effect that is decreased in the absence of Dp53 function. However, over-expression of SCE produce no developmental effects but inhibits DP53-induced apoptosis. Thus, Sce functions as a Dp53-dependent apoptosis inhibitor. The SCE inhibition of DP53-induced apoptosis requires dRYBP, an ubiquitin binding protein and member of the PcG. Moreover, this inhibition of apoptosis involves the reduction of DP53 protein levels. Finally, high levels of SCE inhibit X-ray induced apoptosis as well as the apoptosis associated with tumor growth. We propose that SCE, together with dRYBP, inhibits apoptosis either by epigenetically regulating Dp53 transcription or by controlling the stabilization of DP53 protein levels thus promoting its ubiquitylation for proteaosomal degradation. This function may generate a homeostatic balance between apoptosis and proliferation during development that provides cell survival during the initiation and progression of disease processes.

Waterscape determinants of net mercury methylation in a tropical wetland.

The periphyton associated with freshwater macrophyte roots is the main site of Hg methylation in different wetland environments in the world. The aim of this study was to test the use of connectivity metrics of water bodies, in the context of patches, in a tropical waterscape wetland (Guapore River, Amazonia, Brazil) as a predictor of potential net methylmercury (MeHg) production by periphyton communities. We sampled 15 lakes with different patterns of lateral connectivity with the main river channel, performing net mercury methylation potential tests in incubations with local water and Eichhornia crassipes root-periphyton samples, using (203)HgCl2 as a tracer. Physico-chemical variables, landscape data (morphological characteristics, land use, and lateral connection type of water bodies) using GIS resources and field data were analyzed with Generalized Additive Models (GAM). The net Me(203)Hg production (as % of total added (203)Hg) was expressive (6.2-25.6%) showing that periphyton is an important matrix in MeHg production. The model that best explained the variation in the net Me(203)Hg production (76%) was built by the variables: connection type, total phosphorus and dissolved organic carbon (DOC) in water (AICc=48.324, p=0.001). Connection type factor was the best factor to model fit (r(2)=0.32; p=0.008) and temporarily connected lakes had higher rates of net mercury methylation. Both DOC and total phosphorus showed positive significant covariation with the net methylation rates (r(2)=0.26; p=0.008 and r(2)=0.21; p=0.012 respectively). Our study suggests a strong relationship between rates of net MeHg production in this tropical area and the type of water body and its hydrological connectivity within the waterscape.

Non-lethal sampling for mercury evaluation in crocodilians.

Mercury (Hg) is a ubiquitous environmental contaminant that poses potential threats to ecosystems due to its toxicity to humans and wildlife. The development of non-lethal sampling techniques is a critical step for evaluation of Hg in threatened species in tropical floodplain environments, where most of Hg found is the result of land use and gold mining activities, and more methylation sites are available. We evaluated the spatial and seasonal effectiveness of caudal scutes and claws to estimate Hg bioaccumulation in crocodilians (Caiman yacare), in the scarcely documented Pantanal. Hence, we investigated the potential for Hg bioaccumulation in top predators according to its proximity to mining sites, and in water bodies with different hydrological characteristics and connectivity with the main river during two phases of the flood pulse (dry and flood). The highest Hg concentrations were detected in caimans captured close to mining activities, in claws (2176 ng g(-1) ww) and caudal scutes (388 ng g(-1) ww). THg concentration in claws was related to the flood season and its mean concentration was thirteen fold higher than Hg concentration in scutes during whole year. Both tissues were found to be effective as non-lethal sampling techniques for measuring Hg bioaccumulation in reptiles over time. Nevertheless, claw tissue seems to have a more consistent result, since its constitutional chemical characteristics makes it a better indicator of spatial patterns that influence on Hg exposure.

MicroRNA miR-7 contributes to the control of Drosophila wing growth.

BACKGROUND: The control of organ growth is critical for correct animal development. From flies to mammals, the mechanisms regulating growth are conserved and the role of microRNAs in this process is emerging. The conserved miR-7 has been described to control several aspects of development. RESULTS: Here, we have analyzed the function of miR-7 during Drosophila wing development. We found that loss of miR-7 function results in a reduction of wing size and produces wing cells that are smaller than wild type cells. We also found that loss of miR-7 function interferes with the cell cycle by affecting the G1 to S phase transition. Further, we present evidence that miR-7 is expressed in the wing imaginal discs and that the inactivation of miR-7 increases the expression of Cut and Senseless proteins in wing discs. Finally, our results show that the simultaneous inactivation of miR-7 and either cut, Notch, or dacapo rescues miR-7 loss of function wing size reduction phenotype. CONCLUSIONS: The results from this work reveal, for the first time, that miR-7 functions to regulate Drosophila wing growth by controlling cell cycle phasing and cell mass through its regulation of the expression of dacapo and the Notch signaling pathway.

Cyanobacteria enhance methylmercury production: a hypothesis tested in the periphyton of two lakes in the Pantanal floodplain, Brazil.

The toxic potential of mercury (Hg) in aquatic systems is due to the presence and production of methylmercury (MeHg). Recent studies in tropical floodplain environments showed that periphyton associated with the roots of aquatic macrophytes produce MeHg. Periphyton communities are the first link in the food chain and one of the main MeHg sources in aquatic environments. The aim of this work was to test the hypotheses that the algal community structure affects potential methylation, and ecologically distinct communities with different algal and bacterial densities directly affect the formation of MeHg in the roots of macrophytes. To evaluate these, net MeHg production in the roots of Eichhornia crassipes in relation to the taxonomic structure of associated periphytic algae was evaluated. Macrophyte root samples were collected in the dry and flood season from two floodplain lakes in the Pantanal (Brazil). These lakes have different ecological conditions as a function of their lateral hydrological connectivity with the Paraguay River that is different during times of drought. Results indicated that MeHg production was higher in the flood season than in the dry season. MeHg production rates were higher in the disconnected lake in comparison to the connected lake during the dry season. MeHg production exhibited a strong positive co-variation with cyanobacteria abundance (R(2)=0.78; p<0.0001 in dry; R(2)=0.40; p=0.029 in flood) and with total algal biomass (R(2)=0.86; p<0.0001), and a negative co-variation with Zygnemaphyceae (R(2)=0.50; p=0.0018) in the lake community in dry season. This indicates that ecological conditions that favour the establishment and development of cyanobacteria are associated with higher rates of methylation in aquatic systems. This suggests that cyanobacteria could be a proxy for sites of MeHg production in some natural aquatic environments.

Pesticides in surface water, sediment, and rainfall of the northeastern Pantanal basin, Brazil.

Within the last 25 years an intensive agriculture has developed in the highland regions of Mato Grosso state (Brazil), which involves frequent pesticide use in highly mechanized cash-crop cultures. To provide information on pesticide distribution and dynamics in the northeastern Pantanal basin (located in southern Mato Grosso), we monitored 29 pesticides and 3 metabolites in surface water, sediment, and rainwater of the study area during the main application season. In environmental samples, 19 pesticides and 3 metabolites were detected in measurable quantities, resulting in at least one pesticide detection in 68% of surface water samples (n = 139), 62% of sediment samples (n = 26), and 87% of rainwater samples (n = 91). Surface water samples were most frequently contaminated by endosulfan compounds (alpha-, beta-, -sulfate), ametryn, metolachlor, and metribuzin, although in low (< 0.1 microgram L-1) concentrations. Sediment samples exhibited concentrations up to 4.5 micrograms kg-1 of p,p'-DDT, p,p'-DDE, endosulfan-sulfate, beta-endosulfan, and ametryn. In contrast, rainwater was polluted with substantial amounts of endosulfan, alachlor, metolachlor, trifluralin, monocrotofos, and profenofos (maximum concentrations = 0.3 to 2.3 micrograms L-1) in the highlands. Lowland rainwater samples taken 75 km from the next application area contained 5- to 10-fold lower mean pesticide concentration than in the highlands. Cumulative deposition rates of the pesticide sum within the study period ranged from 423 micrograms m-2 in the highlands to 14 micrograms m-2 in the lowlands. The atmospheric input of pesticides to ecosystems seemed to be of higher relevance in the tropical study area than known from temperate regions.