Cruzipains are the main papain-like cysteine proteases of Trypanosoma cruzi, the protozoan parasite that causes Chagas disease. Encoded by a multigenic family, previous studies have estimated the ...presence of dozens of copies spread over multiple chromosomes in different parasite strains. Here, we describe the complete gene repertoire of cruzipain in three parasite strains, their genomic organization, and expression pattern throughout the parasite life cycle. Furthermore, we have analyzed primary sequence variations among distinct family members as well as structural differences between the main groups of cruzipains. Based on phylogenetic inferences and residue positions crucial for enzyme function and specificity, we propose the classification of cruzipains into two families (I and II), whose genes are distributed in two or three separate clusters in the parasite genome, according with the strain. Family I comprises nearly identical copies to the previously characterized cruzipain 1/cruzain, whereas Family II encompasses three structurally distinct sub-types, named cruzipain 2, cruzipain 3, and cruzipain 4. RNA-seq data derived from the CL Brener strain indicates that Family I genes are mainly expressed by epimastigotes, whereas trypomastigotes mainly express Family II genes. Significant differences in the active sites among the enzyme sub-types were also identified, which may play a role in their substrate selectivity and impact their inhibition by small molecules.
The continued contamination of water sources by pesticides is a problem that involves the life of aquatic organisms and human health, especially in countries whose economy is based on agriculture. ...The need to know the quality of drinking water under these circumstances is a priority for the public health of any community. Passive sampling methods allow the determination of long-term environmental pollutants through a single sample collection, reducing time and cost of analyses. One advantage of passive sampling is that it is possible to calculate a time-weighted average (TWA) concentration value or an equilibrium concentration value, depending on the type of device used and the exposure time. Passive sampling techniques using carbon nanomaterials (CNMs) have a high potential for pesticide sampling in aquatic systems. A device for passive sampling manufactured with CNMs in a microextraction system and recyclable materials was calibrated in laboratory exposure conditions over 15 days. The calibration results showed linear accumulation periods between 5 and 10 days. Sampling rates were between 0.014 and 0.146 mL day
−1
. The sampler was field-tested in the San Francisco river basin in the state of Minas Gerais in Brazil for 7 days. This research allowed for the detection and calculation of TWA concentrations for organochlorine pesticides such as α-HCH, 4,4-DDE, and 4,4-DD in water sources. The manufactured device demonstrated greater sensitivity than the grab sampling processes for the detection of pesticides. The performed passive sampling system using gas chromatography/mass spectrometry (GC/MS) technique allowed for the collection, detection, identification, and quantification of 26 pesticides.
Graphical abstract
This research describes a solid-phase microextraction device using carbon nanomaterials supported on steel threads. The device was used to pre-concentrate and extract 24 pesticides in water. The ...carbon nanomaterials were obtained by a chemical vapor deposition (CVD) process, using methane and acetonitrile as carbon source. The different pesticides were separated, detected, and quantified using gas chromatography coupled to mass spectrometry (GC-MS). The system, optimized and validated in the laboratory, presented good results. Linearity was between 0.0007 and 50.00 μg L−1, with determination coefficients greater than 0.9. The detection and quantification limits were in the range of 0.0002–1.1309 μg L−1 and 0.0007–3.7320 μg L−1, respectively. The studied pesticides presented recovery values in the range of 70 ± 8 to 123 ± 18%. Carbon nanomaterials exhibited high thermal and mechanical resistance, as the same fiber could be used for approximately 300 extractions. The device was applied to analyze environmental water samples collected from the São Francisco river basin in Brazil and in the Chinampas in Mexico City.
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•Manufacture of a microextraction syringe with carbon nanomaterials as receiving phase.•Optimization and validation of a method for pesticide analysis in water. Validation parameters showed satisfactory results.•Application of carbon nanomaterial microextraction syringe in water sources.•Some pesticides banned in agriculture continue to be detected in Brazilian environmental water.
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•Composites based on iron mining waste and graphitic carbon nitride were synthesized.•New iron phases were formed due to the partial decomposition of the carbon nitride.•Paracetamol ...was degraded by an efficient heterogeneous peroxymonosulfate activation.•A mechanism based on the synergetic interactions in the catalysts was proposed.•The best catalyst showed high stability and remained active after five cycles.
In this work, the potential to use an iron mining waste (IW), rich in α-Fe2O3 and α-FeOOH, for the development of composites based on graphitic carbon nitride (CN) is demonstrated. These materials were synthesized through a simple thermal treatment at 550 °C of a mixture containing melamine and different IW mass percentages, giving rise to the catalysts xIWCN (where x is related to the initial mass percentage of IW). The iron phases of the precursor were partially transformed throughout the formation of the composites, in such a way that a mixture of α-Fe2O3 and γ-Fe2O3 was observed in their final composition. Furthermore, structural defects were produced in the carbonaceous matrix of the materials, causing the fragmentation of g-C3N4 and an increase of surface area. The catalytic activities of these composites were evaluated in reactions of peroxymonosulfate activation for the degradation of paracetamol. Among these materials, the composite 20IWCN showed the best catalytic activity, being able to degrade almost 90 % of the total paracetamol in only 20 min of reaction. This catalyst also demonstrated high chemical stability, being successfully utilized in five consecutive reaction cycles, with negligible iron leaching.
Influenza A virus causes annual epidemics which affect millions of people worldwide. A recent Influenza pandemic brought new awareness over the health impact of the disease. It is thought that a ...severe inflammatory response against the virus contributes to disease severity and death. Therefore, modulating the effects of inflammatory mediators may represent a new therapy against Influenza infection. Platelet activating factor (PAF) receptor (PAFR) deficient mice were used to evaluate the role of the gene in a model of experimental infection with Influenza A/WSN/33 H1N1 or a reassortant Influenza A H3N1 subtype. The following parameters were evaluated: lethality, cell recruitment to the airways, lung pathology, viral titers and cytokine levels in lungs. The PAFR antagonist PCA4248 was also used after the onset of flu symptoms. Absence or antagonism of PAFR caused significant protection against flu-associated lethality and lung injury. Protection was correlated with decreased neutrophil recruitment, lung edema, vascular permeability and injury. There was no increase of viral load and greater recruitment of NK1.1(+) cells. Antibody responses were similar in WT and PAFR-deficient mice and animals were protected from re-infection. Influenza infection induces the enzyme that synthesizes PAF, lyso-PAF acetyltransferase, an effect linked to activation of TLR7/8. Therefore, it is suggested that PAFR is a disease-associated gene and plays an important role in driving neutrophil influx and lung damage after infection of mice with two subtypes of Influenza A. Further studies should investigate whether targeting PAFR may be useful to reduce lung pathology associated with Influenza A virus infection in humans.
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•High added value products from thermal cracking of oleic acid and iron ore tailings.•Use of iron ore tailings as an iron source for the cracking of oleic acid.•Cracking reactions led ...to the formation of ketones, hydrogen gas and C3 hydrocarbons.
Iron ore tailings (IOT) are rich in iron oxides and silica and can be used for different applications such as allow the thermal cracking of fatty acids for the production of fuels and products with high added value. Thus, this work aimed to use of IOT as an iron source for the production of high-value products using oleic acid (OA) as carbon sources. These compounds were produced from a thermal decomposition reaction, from the mixture of OA and IOT, in a high pressure reactor (12.5 bar), using the ratio of 1:1 wt (acid:IOT), in temperatures between 250 and 450 °C (3 and 12 h). The results showed that for all reactions, the solid products obtained showed a percentage of less than 6 % of carbon material and different iron phases (Fe2O3, Fe3O4 and FeOOH). For the reactions carried out at 250 and 350 °C/3h the main fraction obtained was the liquid, however the compostion was mainly the starting compound and iron oleate. For the reactions carried out at 400 and 450 °C/3h, the main fraction was gas, mainly hydrogen. For the reaction carried out at 350 °C for 12 h the mass balance showed the formation of similar amounts of liquid and gaseous products. Liquid products formed ketones as the main product, while gaseous products were identified and presented greater selectivity for C3 hydrocarbons.
In this work, magnetic cobalt nanoparticles (CoNPs) were synthesized and applied to the removal of Remazol golden yellow RNL (RGY) from aqueous solutions and textile wastewater. The CoNPs were ...characterized and the Co content found in the CoNPs was 60.38% (m/m). The analysis of X-ray Diffraction (XRD) and Raman Spectroscopy indicated the presence of Co0 and CoO in the composition of the material, as confirmed by Thermogravimetric Analysis coupled to Mass Spectrometry (TG-MS). Images obtained by the Transmission Electron Microscope (TEM) showed that the CoNPs have sizes smaller than 10 nm, sphere morphology and high agglomeration capacity. The results obtained by nitrogen adsorption-desorption suggested that the nanomaterial presented a mesoporous characteristic, low specific surface area (15.70 m2 g−1) and a pore volume and pore diameter of 0.072 cm3 g−1 and 3.64 nm, respectively. CoNPs removed the RGY with high efficiency, reaching almost 100% removal in 30 min. The kinetic results showed that the reaction followed pseudo-second-order kinetics. Additionally, the removal process can be altered depending on the experimental condition. For instance, under acidic conditions, the reductive degradation prevailed, while in neutral or basic conditions, two simultaneous processes occur: reductive degradation and adsorption. Finally, CoNPs were applied to textile wastewater. The results showed high discoloration, reaching almost 88%. However, there was only a 32% decrease in chemical oxygen demand, showing that CoNPs are efficient at removing organic dyes from aqueous solutions.
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•Magnetic cobalt nanoparticles (CoNPs) were synthesized.•CoNPs composition is based on Co and CoO.•There was an elevated removal efficiency of Remazol golden yellow.•Under acidic conditions, the removal process is via reductive degradation.•Under alkaline conditions, the process occurs via degradation and adsorption.
Abstract
Long-term infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) represents a challenge to virus dispersion and the control of coronavirus disease 2019 (COVID-19) ...pandemic. The reason why some people have prolonged infection and how the virus persists for so long are still not fully understood. Recent studies suggested that the accumulation of intra-host single nucleotide variants (iSNVs) over the course of the infection might play an important role in persistence as well as emergence of mutations of concern. For this reason, we aimed to investigate the intra-host evolution of SARS-CoV-2 during prolonged infection. Thirty-three patients who remained reverse transcription polymerase chain reaction (RT-PCR) positive in the nasopharynx for on average 18 days from the symptoms onset were included in this study. Whole-genome sequences were obtained for each patient at two different time points. Phylogenetic, populational, and computational analyses of viral sequences were consistent with prolonged infection without evidence of coinfection in our cohort. We observed an elevated within-host genomic diversity at the second time point samples positively correlated with cycle threshold (Ct) values (lower viral load). Direct transmission was also confirmed in a small cluster of healthcare professionals that shared the same workplace by the presence of common iSNVs. A differential accumulation of missense variants between the time points was detected targeting crucial structural and non-structural proteins such as Spike and helicase. Interestingly, longitudinal acquisition of iSNVs in Spike protein coincided in many cases with SARS-CoV-2 reactive and predicted T cell epitopes. We observed a distinguishing pattern of mutations over the course of the infection mainly driven by increasing A→U and decreasing G→A signatures. G→A mutations may be associated with RNA-editing enzyme activities; therefore, the mutational profiles observed in our analysis were suggestive of innate immune mechanisms of the host cell defense. Therefore, we unveiled a dynamic and complex landscape of host and pathogen interaction during prolonged infection of SARS-CoV-2, suggesting that the host’s innate immunity shapes the increase of intra-host diversity. Our findings may also shed light on possible mechanisms underlying the emergence and spread of new variants resistant to the host immune response as recently observed in COVID-19 pandemic.
Water soluble polysaccharide from
Gracilaria birdiae cultivated along the northeast coast of Brazil was characterized by infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. The ...composition of the polysaccharide in wt% was determined as: β-
d-gal
p (50.3%), 3,6-anhydro-α-
l-gal
p (40.5%) and -α-
l-gal
p-6 sulfate (9.2%). The ratio of
l/
d units (β-
d-gal
p units and 3,6-anhydro-α-
l-gal
p
+
α-
l-gal
p-6 sulfate) is that of an ideal agarose. The sulfate content calculated by S% accounts for 6.4%. 1D and 2D NMR techniques were employed in order to assign the spin system of polysaccharide without partial degradation. The structure is composed of →
4-3,6-anhydro-α-
l-gal
p (1
→
3)β-
d-gal
p 1
→
segments, with the possibility of a α-
l-gal
p unit substituted at the 6-position by sulfate ester.
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•Synthesis of copper oleates from their oxide.•Thermal decomposition for fuel production.•Regeneration of the acid fraction in the liquid produced.•Main fuel gas formed was hydrogen.
...In this work, the thermal decomposition of copper carboxylates formed from CuO and different proportions of oleic acid and CuO was used to produce liquid and gaseous fuels. These reactions gave rise to solid, liquid and gaseous fractions that were studied by different techniques, such as XRD, TG, Raman spectroscopy, FTIR, SEM, TEM, NMR and GC–MS. The liquid fraction obtained was the largest, made up mainly of oleic acid, i.e., the starting reagent was regenerated in the reaction. The gas fraction was the second largest, consisting mainly of hydrogen gas, with selectivity above 80%. The solid fraction was the smallest but showed the formation of metallic copper, carbon and copper(I) oxide. This work showed that it was possible to produce materials from acid oils and metal oxides that, after being thermally decomposed, generated gas fuels of great industrial interest, as well as metal phases, and the regeneration of the acid used as the starting reagent.
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