Summary
Understanding which compounds comprising the complex and dynamic marine dissolved organic matter (DOM) pool are important in supporting heterotrophic bacterial production remains a major ...challenge. We eliminated sources of labile phytoplankton products, advected terrestrial material and photodegradation products to coastal microbial communities by enclosing water samples in situ for 24 h in the dark. Bacterial genes for which expression decreased between the beginning and end of the incubation and chemical formulae that were depleted over this same time frame were used as indicators of bioavailable compounds, an approach that avoids augmenting or modifying the natural DOM pool. Transport‐ and metabolism‐related genes whose relative expression decreased implicated osmolytes, carboxylic acids, fatty acids, sugars and organic sulfur compounds as candidate bioreactive molecules. FT‐ICR MS analysis of depleted molecular formulae implicated functional groups ~ 30–40 Da in size cleaved from semi‐polar components of DOM as bioreactive components. Both gene expression and FT‐ICR MS analyses indicated higher lability of compounds with sulfur and nitrogen heteroatoms. Untargeted methodologies able to integrate biological and chemical perspectives can be effective strategies for characterizing the labile microbial metabolites participating in carbon flux.
We investigated expression of genes mediating elemental cycling at the microspatial scale in the ocean’s largest river plume using, to our knowledge, the first fully quantitative inventory of genes ...and transcripts. The bacterial and archaeal communities associated with a phytoplankton bloom in Amazon River Plume waters at the outer continental shelf in June 2010 harbored ∼1.0 × 10 ¹³ genes and 4.7 × 10 ¹¹ transcripts per liter that mapped to several thousand microbial genomes. Genomes from free-living cells were more abundant than those from particle-associated cells, and they generated more transcripts per liter for carbon fixation, heterotrophy, nitrogen and phosphorus uptake, and iron acquisition, although they had lower expression ratios (transcripts⋅gene ⁻¹) overall. Genomes from particle-associated cells contributed more transcripts for sulfur cycling, aromatic compound degradation, and the synthesis of biologically essential vitamins, with an overall twofold up-regulation of expression compared with free-living cells. Quantitatively, gene regulation differences were more important than genome abundance differences in explaining why microenvironment transcriptomes differed. Taxa contributing genomes to both free-living and particle-associated communities had up to 65% of their expressed genes regulated differently between the two, quantifying the extent of transcriptional plasticity in marine microbes in situ. In response to patchiness in carbon, nutrients, and light at the micrometer scale, Amazon Plume microbes regulated the expression of genes relevant to biogeochemical processes at the ecosystem scale.
Constraining the fate of dissolved organic matter (DOM) delivered by rivers is a key to understand the global carbon cycle, since DOM mineralization directly influences air‐sea CO2 exchange and ...multiple biogeochemical processes. The Amazon River exports large amounts of DOM, and yet the fate of this material in the ocean remains unclear. Here we investigate the molecular composition and transformations of DOM in the Amazon River‐ocean continuum using ultrahigh resolution mass spectrometry and geochemical and biological tracers. We show that there is a strong gradient in source and composition of DOM along the continuum, and that dilution of riverine DOM in the ocean is the dominant pattern of variability in the system. Alterations in DOM composition are observed in the plume associated with the addition of new organic compounds by phytoplankton and with bacterial and photochemical transformations. The relative importance of each of these drivers varies spatially and is modulated by seasonal variations in river discharge and ocean circulation. We further show that a large fraction (50–76%) of the Amazon River DOM is surprisingly stable in the coastal ocean. This results in a globally significant river plume with a strong terrigenous signature and in substantial export of terrestrially derived organic carbon from the continental margin, where it can be entrained in the large‐scale circulation and potentially contribute to the long‐term storage of terrigenous production and to the recalcitrant carbon pool found in the deep ocean.
Key Points
There is a strong gradient in source and composition of DOM in the continuum
Phytoplankton inputs and bacterial/photochemical transformations are significant
A large fraction of the Amazon River DOM is exported from the continental margin
Despite all of the economic problems and environmental discussions on the dangers and hazards of plastic materials, plastic production worldwide is growing at a rate of about 5% per year. Increasing ...techniques for recycling polymeric materials have been developed during the last few years; however, a large fraction of plastics are still being discarded in landfills or subjected to intentional or incidental open-fire burning. To identify specific tracer compounds generated during such open-fire combustion, both smoke particles from burning and plastic materials from shopping bags, roadside trash, and landfill garbage were extracted for gas chromatography-mass spectrometry analyses. Samples were collected in Concón, Chile, an area frequently affected by wildfire incidents and garbage burning, and the United States for comparison. Atmospheric samples from various aerosol sampling programs are also presented as supportive data. The major components of plastic extracts were even-carbon-chain n-alkanes (C16−C40), the plasticizer di-2-ethylhexyl phthalate, and the antioxidants and lubricants/antiadhesives Irganox 1076, Irgafos 168, and its oxidation product tris(2,4-di-tert-butylphenyl)phosphate. Major compounds in smoke from burning plastics include the non-source-specific n-alkanes (mainly even predominance), terephthalic acid, phthalates, and 4-hydroxybenzoic acid, with minor amounts of polycyclic aromatic hydrocarbons (including triphenylbenzenes) and tris(2,4-di-tert-butylphenyl)phosphate. 1,3,5-Triphenylbenzene and tris(2,4-di-tert-butylphenyl)phosphate were found in detectable amounts in atmospheric samples where plastics and refuse were burned in open fires, and thus we propose these two compounds as specific tracers for the open-burning of plastics.
The presence of mainstream medicine in local medical systems inserts a set of external treatments and concepts that generate adjustments in the local conceptions of health and disease. What points in ...the system are most receptive to change? Who are the residents most likely to adopt these external treatments to deal with diseases? To answer these questions, this work used a study model consisting of the simultaneous use of medicinal plants and modern medicine, testing whether diseases that require greater treatment efforts are the main targets of adherence to modern medicine and if socioeconomic characteristics of residents can cause intracultural variation in relation to simultaneous use. To obtain socioeconomic data on the knowledge of medicinal plants and simultaneous use of these resources with modern medicine, semistructured interviews were conducted in a rural community that has easy access to modern medicine. Participatory workshops were held to access the local perceptions about the frequency of occurrence and severity of illnesses. A multilevel logistic regression model was applied for data analysis. We found that chronic, severe and frequently occurring diseases in the community tended to show greater simultaneous use locally. Among the socioeconomic factors, we determined that high educational levels positively influenced the combined use of plants and modern medicine. The need to ensure the cure of frequent, severe and chronic diseases is a factor that leads residents to seek a greater number of possible treatments, stimulating the combined use of plants and modern medicine. Residents with higher educational levels were more likely to use a combination of treatments than those with lower educational levels, demonstrating that more participation in formal education may facilitate the combined use of medicinal plants and modern medicine.
Skeletal muscle synthesizes, stores, and releases body L-glutamine (GLN). Muscle atrophy due to disabling diseases triggers the activation of proteolytic and pro-apoptotic cell signaling, thus ...impairing the body's capacity to manage GLN content. This situation has a poor therapeutic prognosis.
Evaluating if oral GLN supplementation can attenuate muscle wasting mediated by elevated plasma cortisol and activation of caspase-3, p38MAPK, and FOXO3a signaling pathways in soleus and gastrocnemius muscles of rats submitted to 14-day bilateral hindlimbs immobilization.
Animals were randomly distributed into six groups: non-immobilized rats (Control), control orally supplemented with GLN (1 g kg
) in solution with L-alanine (ALA: 0.61 g kg
; GLN+ALA), control orally supplemented with dipeptide L-alanyl-L-glutamine (DIP; 1.49 g kg
), hindlimbs immobilized rats (IMOB), IMOB orally GLN+ALA supplemented (GLN+ALA-IMOB), and IMOB orally DIP supplemented (DIP-IMOB). Plasma and muscle GLN concentration, plasma cortisol level, muscle caspase-3 activity, muscle p38MAPK and FOXO3a protein content (total and phosphorylated forms), and muscle cross-sectional area (CSA) were measured.
Compared to controls, IMOB rats presented: a) increased plasma cortisol levels; b) decreased plasma and muscle GLN concentration; c) increased muscle caspase-3 activity; d) increased total and phosphorylated p38MAPK protein content; e) increased FOXO3a and decreased phosphorylated FOXO3a protein content; f) reduced muscle weight and CSA befitting to atrophy. Oral supplementation with GLN+ALA and DIP was able to significantly attenuate these effects.
These findings attest that oral GLN supplementation in GLN+ALA solution or DIP forms attenuates rats' skeletal muscle mass wasting caused by disuse-mediated muscle atrophy.
The purpose of this review is to highlight progress in unraveling carbon cycling dynamics across the continuum of landscapes, inland waters, coastal oceans, and the atmosphere. Earth systems are ...intimately interconnected, yet most biogeochemical studies focus on specific components in isolation. The movement of water drives the carbon cycle, and, as such, inland waters provide a critical intersection between terrestrial and marine biospheres. Inland, estuarine, and coastal waters are well studied in regions near centers of human population in the Northern hemisphere. However, many of the world’s large river systems and their marine receiving waters remain poorly characterized, particularly in the tropics, which contribute to a disproportionately large fraction of the transformation of terrestrial organic matter to carbon dioxide, and the Arctic, where positive feedback mechanisms are likely to amplify global climate change. There are large gaps in current coverage of environmental observations along the aquatic continuum. For example, tidally-influenced reaches of major rivers and near-shore coastal regions around river plumes are often left out of carbon budgets due to a combination of methodological constraints and poor data coverage. We suggest that closing these gaps could potentially alter global estimates of CO2 outgassing from surface waters to the atmosphere by several-fold. Finally, in order to identify and constrain/embrace uncertainties in global carbon budget estimations it is important that we further adopt statistical and modeling approaches that have become well-established in the fields of oceanography and paleoclimatology, for example.
The ecological apparency hypothesis in ethnobotanical studies predicts that the apparent plants (i.e., the most easily found in the vegetation) would be the most commonly collected and used by ...people. To test this hypothesis, it has been used the concept of use value (VU), which measures the relative importance of useful plants for a group of people. However, the use value has got some limitations, including the fact that it does not distinguish “current use” (plants which are effectively used) from “potential use” (well known plants, however not used). Therefore, this study has tested whether the obtained results through three different use value calculations could be useful in testing the ecological apparency hypothesis. These calculations have included the current use value, the potential use value, and the general use value. It has been carried out a vegetation survey and an interview for residents from the rural communities from Barrocas and Cachoeira (Soledade, Paraíba, Brazil). It has been used Spearman's coefficient to correlate phytosociological and ethnobotanical data. It has been observed that phytosociological parameters in Cachoeira were not correlated with any of the use values calculations, except the relationship between the current use value and the relative dominance (
r
s
= 0.57;
p < 0.05). In Barrocas, every use value calculation was correlated with the basal area and the relative dominance. When each category of use is analyzed separately, it has been observed that there was no correlation between the use value and the phytosociological parameters, except for the construction category, in which the current use value in Cachoeira was correlated with the relative dominance (
r
s
= 0.63;
p < 0.05), importance value (
r
s
= 0.67;
p < 0.01), relative frequency (
r
s
= 0.71;
p < 0.05), and relative density (
r
s
= 0.72;
p < 0.01). In Barrocas, the UVc for the construction category was correlated with relative frequency (
r
s
= 0.69;
p < 0.05) and relative density (
r
s
= 0.66;
p < 0.01). These results have suggested that, the use value calculation, which takes into consideration just the current use of the species, is the one that best fits in the ecological apparency hypothesis.
► We used three different calculations of use-value to test the ecological apparency hypothesis. ► These calculations included the current use value, potential use value, and general use value. ► The current use-value calculation is the best suited to reveal relationship between the relative importance of a resouce and its apparency.
During the 2010 Deepwater Horizon oil spill in the Gulf of Mexico, three million liters of chemical dispersants (Corexit 9500 and 9527) were directly applied at the discharging wellhead at 1500m ...water depth. Such a deep-water large-scale application was unprecedented and the effect of dispersants on oil biodegradation is not yet completely understood. The present study explores the biodegradation of oil, dispersant, dispersed oil or dispersed oil and nutrients at the molecular level using ultra-high resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR–MS) following a laboratory experiment with Gulf deep water. Oil-derived molecular formulae exhibited a specific molecular fingerprint and were mainly observed in the mass range <300Da. The relative abundance of heteroatom-containing (N, S, and P) compounds decreased over time in the oil-only treatments, indicating that they may have served as nutrients when oil-derived hydrocarbons were metabolized. Relative changes over time in the molecular composition were less pronounced in the dispersed oil treatments compared to the oil-only treatments, suggesting that dispersants affected the metabolic pathways of organic matter biodegradation. In particular, dispersant addition led to an increase of S-containing organic molecular formulae, likely derived from the surfactant di-octyl sulfosuccinate (DOSS). DOSS and several dispersant-derived metabolites (with and without S) were still detectable after six weeks of incubation, underscoring that they were not rapidly biodegraded under the experimental conditions. FT-ICR–MS fragmentation studies allowed tentatively assigning structures to several of these molecules, and we propose that they are degradation products of DOSS and other dispersant components. The present study suggests preferential degradation, transformation and enrichment of distinct dispersant molecules, highlighting the need to include these compounds when tracking Corexit-derived compounds in the environment.
Domestic wood collection affects plant communities through constant biomass removal. We assessed the effects of wood collection for firewood and fence construction on tree community structure in a ...seasonally dry tropical forest in Brazil. We described the harvest patterns of wood products. Further, we evaluated the effects of rainfall levels and wood collection on tree community structure. Most wood collection for firewood was concentrated within a small subset of dominant species. Wood collection for building fences was less influenced by species abundance. Species richness was positively associated with rainfall. Wood collection increased community evenness and negatively affected total density. The dominant species were not affected by wood collection. Domestic use of wood has a low impact on tree diversity in human-dominated dry forests. Nevertheless, some of the most used species for building fences are potentially threatened. The effects of firewood collection can be mitigated through (1) offering subsidies aimed at fuel transition to liquefied petroleum gas or (2) developing and distributing more efficient cookstoves. The effects of wood collection for building fences can be mitigated through promoting the use of (1) living fences or (2) fewer stakes. In addition, the populations of the most commonly used species should be recovered.
•Local people display an indiscriminate behaviour during firewood collection.•Wood collection for building fences seems to be guided by local preferences.•Low scale wood collection increases tree community evenness in dry forests.•Low scale wood collection reduces the total abundances in the dry forests.
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