RESUMEN
Mass shootings are becoming more frequent in the United States, as we routinely learn from the media about attempts that have been prevented or tragedies that destroyed entire communities. To date, there has been limited understanding of the modus operandi of mass shooters, especially those who seek fame through their attacks. Here, we explore whether the attacks of these fame-seeking mass shooters were more surprising than those of others and clarify the link between fame and surprise in mass shootings. We assembled a dataset of 189 mass shootings from 1966 to 2021, integrating data from multiple sources. We categorized the incidents in terms of the targeted population and shooting location. We measured "surprisal" (often known as "Shannon information content") with respect to these features, and we scored fame from Wikipedia traffic data-a commonly used metric of fame. Surprisal was significantly higher for fame-seeking mass shooters than non-fame-seeking ones. We also registered a significant positive correlation between fame and surprisal controlling for the number of casualties and injured victims. Not only do we uncover a link between fame-seeking behavior and surprise in the attacks but also we demonstrate an association between the fame of a mass shooting and its surprise.
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Armas de Fuego , Violencia con Armas , Estados Unidos , HumanosRESUMEN
Microorganisms that can survive in saline environments, known as halotolerant or halophilic organisms, have a wide range of current and potential uses in biotechnology. In this study, it was aimed to determine the carotenoids of halophilic archaea strains isolated from the brine samples taken from different points of Salt Lake (Turkey) and determine the antioxidant activities of their carotenoids. To identify the halophilic archaea strains, they were cultivated in MAM JCM 168 medium and subjected to antibiotic susceptibility, fatty acid, two-dimensional and three-dimensional imaging by scanning electron microscopy and atomic force microscopy, biochemical and phylogenetic assays. The findings show that five different halophilic archaea strains have been identified as Halorubrum lipolyticum, Halorubrum sodomense, Haloarcula salaria, Halorubrum chaoviator, and Haloarcula japonica with 98% and above similarity ratio. The main fatty acids of all haloarchaeal strains were octadecanoic acid (C18:0) and palmitic acid (C16:0). The major carotenoid of the species was determined as all-trans bacterioruberin, and different carotenoid types such as lycopene, ß-carotene, and 2-isopentenyl-3,4-dehydrorodopin were found as well as bacterioruberin isomers. The antioxidant activities of carotenoids extracted from the species were analyzed by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging method and the extracts showed antioxidant activity statistically significantly higher than ascorbic acid and butylated hydroxytoluene as reference products (p < 0.05).
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Antioxidantes , Halorubrum , Antioxidantes/farmacología , Antioxidantes/química , Ácidos Grasos , Filogenia , Carotenoides/químicaRESUMEN
To investigate the potential benefits of the catadromous thinlip grey mullet (Chelon ramada Risso, 1827) migration to freshwater, the total lipid content and fatty acid (FA) profile of female's muscle and gonads caught in both the estuary and river were analyzed. The freshwater contingent presented a higher body condition, greater muscle gross energy, and larger gonads with higher lipid reserves. These animals showed a muscle profile rich in C16:1n-7 and lower LC-PUFA that contrast with the higher relative amount of C18:1n-9, n-3 FA, and unsaturated LC-PUFA, such as C18 and C20 FA found in the estuarine contingent. The gonads of both contingents showed a constant and high relative amount of polyunsaturated FAs (PUFA, 37%). However, in terms of essential fatty acids (EFAs), the estuarine contingent had a higher relative amount of C18:2n-6, C20:4n-6, C20:5n-3, and C22:6n-3. On the other hand, the freshwater contingent showed a higher relative amount of n-3 FA precursors, namely C18:3n-3, and a still low relative amount of C22:6n-3. This suggests a mismatch between the metabolic omega-3 pathway and the physiological maturity stages, similar to a phenomenon of dormancy. In this sense, not all these individuals may reproduce annually, and the later stages of gonad development will require supplementary energy derived from feeding at the estuary. Thus, freshwater migration may promote a reproductive strategy enabling adults to take advantage of the warm and food-rich summer/autumn period, adjust spawning and juvenile appearance, and reduce the population's exposure to habitat changes and/or stochastic events.
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Ácidos Grasos , Agua Dulce , Smegmamorpha , Animales , Smegmamorpha/metabolismo , Femenino , Ácidos Grasos/metabolismo , Migración Animal/fisiología , Gónadas/metabolismo , Músculos/metabolismoRESUMEN
Egg preference as a source of protein also provides beneficial fatty acids, vital for human consumption. However, rich in lipid products are prone to oxidative damage. The study aims to determine the effect of supplementing biogenic selenium (Se) from Stenotrophomonas maltophilia, ADS18 (ADS18) in laying hens' diet on yolk lipid oxidation status (MDA), beta-carotene (ß-carotene) content, cholesterol, fatty acids, Se, and vitamin E (VE) level. A total of one hundred and twenty (120) laying hens of Lohmann Brown strains aged 50 weeks, weighing 1500 to 2000 g were reared individually in A-shape two-tier stainless-steel cages sized 30 cm x 50 cm x 40 cm (width, depth height). The hens were randomly allotted into four treatments with six replications in a complete randomised design for the period of 12 weeks. The basal diet contains 100 mg/kg VE. Treatment diets consist of basal diet as control, SS containing 0.3 mg/kg sodium selenite, Se-yeast containing 0.3 mg/kg selenised yeast, and VADS18 containing 0.3 mg/kg of ADS18. Forty-eight eggs were collected and freeze-dried biweekly for analysis. The results of the present study showed that hens supplemented ADS18 had significantly (P < 0.05) lower MDA and cholesterol levels while their egg yolks had higher levels of Se and mono-unsaturated fatty acids (MUFA). The control group had significantly (P < 0.05) higher saturated fatty acid (SFA) contents than the VE and dietary Se-supplemented groups, while the ADS18 group had the lowest SFA contents. Conversely, in comparison to the inorganic and control groups, the VE content of the egg yolk was significantly (P < 0.05) higher in organic Se-supplemented (Se-yeast and VADS18) groups. Hens with SS supplementation had significantly (P < 0.05) higher egg yolk ß-carotene content. When compared to other treatment groups, the control group had higher (P < 0.05) polyunsaturated fatty acids (PUFA) content. The ADS18 is therefore deemed comparable to other Se sources. To prevent Se toxicity, however, a better understanding of the levels of ADS18 incorporation in poultry diets is required.
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Alimentación Animal , Pollos , Dieta , Suplementos Dietéticos , Yema de Huevo , Selenio , Vitamina E , Animales , Femenino , Suplementos Dietéticos/análisis , Alimentación Animal/análisis , Selenio/administración & dosificación , Selenio/análisis , Yema de Huevo/química , Vitamina E/administración & dosificación , Vitamina E/análisis , Dieta/veterinaria , Distribución Aleatoria , Ácidos Grasos/análisis , Ácidos Grasos/metabolismo , Lípidos/análisis , beta Caroteno/análisis , beta Caroteno/administración & dosificación , beta Caroteno/metabolismoRESUMEN
Familial adult myoclonus epilepsy (FAME) is a genetic condition characterized by the occurrence of cortical tremor, myoclonus, and epilepsy. To date, there is neither a curative nor a preventive treatment for FAME. Clinical management is essentially symptomatic and based on antiseizure medications (ASMs). The choice of the correct therapeutic option is limited to ASMs that have both an antiseizure and an antimyoclonic effect, such as valproate, levetiracetam, benzodiazepines, and perampanel. However, these medications control seizures well while having a limited effect on myoclonus and cortical tremor. In addition, many ASMs, including sodium channel blockers and gabapentin, are contraindicated in this condition. The ideal therapeutic option would be a precision treatment able to revert the genetic defect underlying it. Nevertheless, this does not seem to be an option that will be available soon.
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Epilepsias Mioclónicas , Epilepsia , Mioclonía , Adulto , Humanos , Mioclonía/tratamiento farmacológico , Temblor/tratamiento farmacológico , Epilepsia/tratamiento farmacológico , Epilepsias Mioclónicas/tratamiento farmacológico , Epilepsias Mioclónicas/genética , Ácido Valproico/uso terapéutico , Anticonvulsivantes/uso terapéuticoRESUMEN
In recent years, a large group of familial epilepsies and hereditary ataxias have emerged, caused by an extraordinary type of a novel pentanucleotide repeat expansion that has arisen in a preexisting nonpathogenic repeat tract. Remarkably, these insertions have occurred in noncoding regions of genes expressed in the cerebellum, but with highly diverse functions. These conditions, clinically very heterogeneous, may remain underdiagnosed in patients with atypical phenotypes and age at onset. They share, however, many genetic and phenotypic features, and discovery or detection of their pathogenic pentanucleotide repeats for diagnostic purposes can be achieved using recent bioinformatic methods. Here, we focus on the latest advances regarding the peculiar group of pentanucleotide repeat-related disorders beyond epilepsies.
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Ataxias Espinocerebelosas , Humanos , Ataxias Espinocerebelosas/genética , Ataxias Espinocerebelosas/patología , Proteínas del Tejido Nervioso/genética , Cerebelo/patología , Repeticiones de MicrosatéliteRESUMEN
Familial adult myoclonus epilepsy (FAME) is an autosomal dominant condition characterized by the association of myoclonic tremor and epilepsy mainly with onset in adulthood. The clinical course is non-progressive or slowly progressive, as epilepsy is commonly controlled with appropriate antiseizure medication and individuals have a normal life expectancy. However, the myoclonus severity increases with age and leads to some degree of disability in the elderly. Because the non-coding repeat expansions responsible for FAME are not detected by routine genetic tests being used at this time, a clinical diagnosis accompanied by neurophysiological testing remains essential to guide the geneticist on the selection of the specific genetic technique.
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Epilepsias Mioclónicas , Mioclonía , Humanos , Adulto , Anciano , Mioclonía/diagnóstico , Mioclonía/genética , Mioclonía/complicaciones , Epilepsias Mioclónicas/diagnóstico , Epilepsias Mioclónicas/genética , Epilepsias Mioclónicas/complicaciones , Linaje , Progresión de la EnfermedadRESUMEN
Nitrogen stress can influence microalgae's growth characteristics, and microalgae grown in nitrogen-deficient conditions may produce higher or lower levels of biotechnological products as a result of metabolic changes. In photoautotrophic and heterotrophic cultures, nitrogen limitation has been proven effective in promoting lipid accumulation. In spite of this, no study has demonstrated a significant correlation between lipid content and other biotechnological products such as bioactive compounds (BACs). This research examines a strategy for lipid accumulation as well as the potential production of BACs with antibacterial properties in parallel with that strategy. This concept involved the treatment of the microalga Auxenochlorella protothecoides with low and high concentrations of ammonium (NH4+). This particular experiment reached a maximum lipid content of 59.5% using a 0.8 mM NH4+ concentration, resulting in the yellowing of the chlorophyll levels. Agar diffusion assays were conducted to determine the antibacterial activity of different extracts derived from the biomass when stressed with different levels of nitrogen. Algal extracts prepared by a variety of solvents showed different levels of antibacterial activity against representative strains of both gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria. Among the extracts tested, 500 mg/L ethyl acetate extract had the greatest antibacterial activity against Escherichia coli. In order to identify the components responsible for the extract's antibacterial activity, fatty acid methyl ester (FAME) analysis was performed. It has been suggested that the lipid fraction may be a valuable indicator of these activities since some lipid components are known to possess antimicrobial properties. In this regard, it was found that the amount of polyunsaturated fatty acid (PUFA) significantly decreased by 53.4% under the conditions with the highest antibacterial activity observed.
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Chlorophyta , Microalgas , Nitrógeno/metabolismo , Chlorophyta/metabolismo , Ácidos Grasos/análisis , Antibacterianos/farmacología , Antibacterianos/metabolismo , Escherichia coli/metabolismo , Microalgas/metabolismo , BiomasaRESUMEN
The increasing interest in bioplastics, with regard to future environmental issues, has rendered research on bioplastic biodegradation highly important. However, only a few tools directly monitor the degradation of bioplastics without measuring the levels of gaseous products, such as carbon dioxide. Classical nonquantitative methods, such as clear zone tests on solid plates, and less-sensitive weight-loss experiments in liquid media measured using a precision scale, are still employed to screen the microbial players associated with bioplastic degradation and monitor the biodegradation rates. However, the simultaneous monitoring of the degradation of each component of blended bioplastics has not been previously reported. In the present study, to provide information regarding the degradation rates and compositional changes of different bioplastics in a blend in a time-dependent manner, we simultaneously monitored and quantified the degradation of four bioplastics, polyhydroxybutyrate (PHB), polybutylene succinate (PBS), polycaprolactone (PCL), and poly(butylene adipate-co-terephthalate) (PBAT), by Bacillus sp. JY36 using gas chromatography-mass spectrometry (GC-MS) analysis after fatty acid methyl ester (FAME) derivatization. Our results demonstrate the feasibility of using the GC-MS-based method described here to obtain comprehensive data regarding blended bioplastics and their degradation. Moreover, our findings indicate that this method may support classical analytic tools for assessing bioplastic biodegradation.
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Poliésteres , Biodegradación Ambiental , Cromatografía de Gases y Espectrometría de Masas , Poliésteres/metabolismoRESUMEN
Microalgae have garnered much contemplation as candidates to fix CO2 into valuable compounds. Although microalgae have been studied to produce various metabolites, they have not yet proved successful for commercialization. Since, handling such problems practically requires satisfying multiple parameters simultaneously, we put forth a multi-parameter optimization strategy to manipulate the carbon metabolism of Scenedesmus sp. to improve biomass production and enhance CO2 fixation to increase the production of fuel-related metabolites. The Box-Behnken design method was applied with CO2 concentration, CO2 sparging time and glucose concentration as independent variables; biomass and total fatty acid methyl ester (total FAME) content were analyzed as response variables. The strain is supplemented with both CO2 and glucose with an aim to enhance carbon flux and rechannel it towards carbon fixation. As per the results obtained in this study, Scenedesmus sp. could effectively exploit high CO2 concentration (15%) for longer duration under high concentration of glucose supplementation (9 g/L) producing a biomass of 635.24 ± 39.9 µg/mL with a high total fatty acid methyl ester (FAME) content of 71.29 ± 4.2 µg/mg, significant acetyl-CoA carboxylase enzyme activity and a favorable fatty acid profile: 35.8% palmitic acid, 10.5% linoleic acid and 30.6% linolenic acid. The carbohydrate content was maximum at 10% CO2 sparged for the longest duration of 90 min under glucose concentration of 9 g/L. This study puts forth an optimal design that can provide evidence on comprehending the carbon assimilation mechanism to enhance production of biomass and biofuels and provide conditions to microalgal species to tolerate CO2 rich flue gas.
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Microalgas , Scenedesmus , Biomasa , Carbono , Dióxido de CarbonoRESUMEN
Linen fibres were coated with a glow-in-the-dark photoluminescence, flame-retarding, and hydrophobic smart nanocomposite using the pad-dry-curing process. Ecologically friendly ammonium polyphosphate and lanthanide-activated strontium aluminium oxide (LSAO) nanoparticles were immobilized into linen fabric using eco-friendly room-temperature-vulcanizing silicone rubber. Different analytical techniques were used to examine the morphological characteristics and elemental compositions of LSAO nanoparticles and treated linen textiles. The self-extinguishing properties of the treated linen textiles were tested for their fire resistance. After 24 washing cycles, the coated linen samples retained their flame-retarding properties. The treated linen's superhydrophobicity rose in direct proportion to the LSAO concentration. After being excited at 365 nm, the colourless luminescent film that was coated on linen surface gave out an emission wavelength of 519 nm. The photoluminescent linen was monitored to create a range of different colours, including off-white in daytime light and green under ultraviolet (UV) light radiation, according to the Commission Internationale de l'éclairage laboratory colorimetric coordinates and photoluminescence spectra. Emission, excitation, and lifetime spectral analysis of the treated linen revealed persistent phosphorescence. For mechanical and comfort evaluation, the coated linen textiles' bending length and air permeability were assessed. Good UV light shielding and enhanced antibacterial activity were detected in the treated linens.
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Nanopartículas , Textiles , Óxido de Aluminio , Antibacterianos/química , Ropa de Cama y Ropa Blanca , Luminiscencia , Nanopartículas/química , EstroncioRESUMEN
Many famous people have disclosed their mental illness to erase the harmful effects of stigma. This study examines the relative impact of disclosure stories from people who are or are not celebrities. We expected noncelebrities would be viewed as more similar and likeable and therefore have greater effects on stigma change. Research participants from an MTurk panel viewed self-disclosure stories from celebrity, Mariah Carey, or noncelebrity, Malia Fontecchio. Participants completed the Difference and Disdain Scale prior to reviewing the vignettes and immediately after each one. Participants also completed scales representing perceptions of fame, dissimilarity, and likeability of the person in each story. Results supported hypotheses: Mariah Carey was perceived as more famous, more dissimilar, and less likeable than Malia Fontecchio. Reading the Malia Fontecchio story led to greater improvement in disdain stigma than the Mariah Carey story. Implications for the varied role of celebrity status in stigma change are discussed.
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Personajes , Trastornos Mentales , Humanos , Autorrevelación , Estigma SocialRESUMEN
The present study involved feeding of tender coconut water concentrate (TCW) and testa phenolic concentrate (PHE) to high fat fed animals. Analysis of serum showed increased HDL-C in concentrates treated group and therefore higher protection against atherogenesis compared to high fat fed group. Lesser fecal fat content and higher level of liver cholesterol were observed in high fat fed group, treatments with TCW and PHE ameliorated significantly. Fat content in the organs (liver, heart, kidney and adipose) of HFD group was high. Furthermore, certain fatty acids observed in the tissues were 14:0, 16:0, 18:0, 18:1, 18:2, 20:0, 20:3 and 20:4, among which 14:0, 16:0 & 18:0 are the major saturated fatty acids that increased significantly in high fat fed group when compared with starch fed group and ameliorated with TCW and PHE dose dependently. These results clearly indicate both the concentrates (TCW and PHE) restrict excess accumulation of lipids and altered composition of fatty acids in tissues as well as serum which are the risk factors for development of insulin resistance, hyperlipidemia, dyslipidemia etc., related to obesity. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13197-021-05178-2.
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During a study of the bacterial diversity of mangrove habitats, a novel Gram-stain-negative, rod-shaped bacterium designated as SAOS 153DT was isolated. Sequence alignment and molecular phylogenetic analyses based on 16S rRNA and core gene sequence of strain SAOS 153DT with closely related taxa revealed a sequence identity of 99.4â% and clustering with Yangia pacifica DX5-10T. The fatty acids summed feature 8 (C18:1 ω7c/C18:1 ω6c) and the lipids phosphatidylglycerol, phosphatidylethanolamine and an unknown phospholipid were the major components of the cell wall. The only ubiquinone type present was Q-10. The genomic DNA G+C content of the strain calculated from whole genome sequencing was 66.9 mol%. These chemotaxonomic and genomic characteristics supported the molecular phylogenetic analysis and placed the strain well within the radiation of the genus Yangia. The overall genome related indices using digital DNA-DNA hybridization (35.4â%) and ortho-average nucleotide identity (88.1â%) values were much lower than the recommended thresholds for species delineation, which further consolidated the novel species status of strain SAOS 153DT within the genus Yangia as Yangia mangrovi sp. nov. The type strain is SAOS 153DT (=JCM 31345T=KCTC 52280T=MTCC 12749T).
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Roseobacter , Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano/genética , Ácidos Grasos/química , Fosfolípidos , Filogenia , ARN Ribosómico 16S/genética , Rhodobacteraceae , Análisis de Secuencia de ADN , Suelo , UbiquinonaRESUMEN
The current research focuses on the Intracellular biosynthesis of Ag/AgCl nanohybrids in microalgae, Scenedesmus sp. The effect of biosynthesis process on growth and lipid profile of cells is key element of this study. Ag/AgCl nanohybrids synthesized intracellularly were characterized by UV-Vis spectrophotometer, Powder X-Ray Diffraction (P-XRD), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM). 10-20 nm and 10-50 nm sized spherical shaped nanoparticles of polycrystalline nature were grown using 0.5 and 1 mM of AgNO3 precursor, respectively and Scenedesmus sp. as reducing agent. Total lipid content of the cells treated with 0.5 mM and 1 mM AgNO3 was static and found to be 43.2 ± 0.01 µg/mL and 48.2 ± 0.02 µg/mL respectively at 120 h of Ag/AgCl nanoparticles biosynthesis. FAME (Fatty Acid Methyl Ester) profile was improved due to intracellular nanoparticles biosynthesis with maximum C16:0 (palmitic acid) (35.7%) in cells treated with 0.5 mM AgNO3 used for Ag/AgCl nanohybrids synthesis. Palmitic acid in cells exposed to 0.5 mM concentration of metallic precursor increased by 75.86%. Synthesized nanoparticles were tested on four bacterial strains to establish its antibacterial efficiency showing appropriate zone of inhibition at varying concentrations. Present study efficiently demonstrates the utility of microalgae integrating nanoparticles biosynthesis and lipid accumulation.
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Nanopartículas del Metal , Scenedesmus , Antibacterianos/farmacología , Lípidos , PlataRESUMEN
Biodiesel is increasingly being used in automotive and other engine applications because of its potential to contribute to the reduction of CO2 and other harmful emissions. However, biodiesel is known to be more corrosive in contact with metallic components than petroleum diesel. This work explores the corrosion of aluminium, steel, brass and copper metallic coupons exposed to B100 biodiesel at 25, 80, 90, 100, 110 and 120 °C. The metals that were chosen are commonly found in automotive engines. The B100 in each experiment was sampled at 48, 100, 150, 200 and 270 h and examined by GCMS to determine compositional changes. It was found that corrosion rates for copper were 10x faster than brass and approximately 100x faster than for mild steel, Al7075 and Al1050. Activation energies for corrosion were calculated from mass loss and ICP, with good correlation between the two methods for Cu containing samples. By mass loss, the activation energies for Cu, Brass, Al7075 and Al1050 were calculated to be -47.9 kJ mol-1, -85.4 kJ mol-1, -86.7 kJ mol-1 and -54.4 kJ mol-1, respectively. By ICP analysis, the activation energies for Cu, Brass, and Al7075 were calculated to be -57.9 kJ mol-1, -90 kJ mol-1 and -140 kJ mol-1, respectively. Corrosion rates in brass and copper samples were faster owing to the direct reaction of copper with the fatty acid. The copper was found to cause chain scission and greater degradation of the biodiesel.
RESUMEN
Waste cooking oil (WCO) is a valuable feedstock for the synthesis of biodiesel but the product exhibits poor oxidative stability. Techniques available for assessing this parameter are generally expensive and time-consuming, hence the purpose of this study was to develop and validate a rapid and reliable predictive system based on signals from the sensors of a commercial hand-held e-nose instrument. Biodiesels were synthesized from soybean oil and six samples of WCO, and their physicochemical characteristics and oxidative stabilities determined before and after storage in different types of containers for 30 or 60 days at room temperature or 43 °C. Linear regression models were constructed based on principal component analysis of the signals generated by all 32 e-nose sensors and stochastic modeling of signal profiles from individual sensors. The regression model with principal components as predictors was unable to explain the oxidative stability of biodiesels, while the regression model with stochastic parameters (combining signals from 11 sensors) as predictors showed an excellent goodness of fit (R2 = 0.91) with a 45-sample training set and a good quality of prediction (R2 = 0.84) with a 18-sample validation set. The proposed e-nose system was shown to be accurate and efficient and could be used to advantage by producers/distributors of biodiesel in the assessment fuel quality.
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Nonsense mutations turn a coding (sense) codon into an in-frame stop codon that is assumed to result in a truncated protein product. Thus, nonsense substitutions are the hallmark of pseudogenes and are used to identify them. Here we show that in-frame stop codons within bacterial protein-coding genes are widespread. Their evolutionary conservation suggests that many of them are not pseudogenes, since they maintain dN/dS values (ratios of substitution rates at non-synonymous and synonymous sites) significantly lower than 1 (this is a signature of purifying selection in protein-coding regions). We also found that double substitutions in codons-where an intermediate step is a nonsense substitution-show a higher rate of evolution compared to null models, indicating that a stop codon was introduced and then changed back to sense via positive selection. This further supports the notion that nonsense substitutions in bacteria are relatively common and do not necessarily cause pseudogenization. In-frame stop codons may be an important mechanism of regulation: Such codons are likely to cause a substantial decrease of protein expression levels.
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Codón sin Sentido , Codón de Terminación/genética , Sistemas de Lectura Abierta/genética , Células Procariotas/metabolismo , Bacterias/clasificación , Bacterias/genética , Proteínas Bacterianas/clasificación , Proteínas Bacterianas/genética , Secuencia de Bases , Evolución Molecular , Modelos Genéticos , Filogenia , Mutación Puntual , Seudogenes/genética , Selección Genética , Homología de Secuencia de Ácido NucleicoRESUMEN
To meet the increasing global demand of biodiesel over the next decades, alternative methods for producing one of the key constituents of biodiesel (e.g. fatty acid methyl esters (FAMEs)) are needed. Algal biodiesel has been a long-term target compromised by excessive costs for harvesting and processing. In this work, we engineered cyanobacteria to convert carbon dioxide into excreted FAME, without requiring methanol as a methyl donor. To produce FAME, acyl-ACP, a product of the fatty acid biosynthesis pathway, was first converted into free fatty acid (FFA) by a thioesterase, namely 'UcFatB1 from Umbellularia californica. Next, by employing a juvenile hormone acid O-methyltransferase (DmJHAMT) from Drosophila melanogaster and S-adenosylmethionine (SAM) as a methyl donor, FFAs were converted into corresponding FAMEs. The esters were naturally secreted extracellularly, allowing simple product separation by solvent overlay as opposed to conventional algae biodiesel production where the algae biomass must first be harvested and processed for transesterification of extracted triacylglycerols (TAGs). By optimizing both the promoter and RBS elements, up to 120 mg/L of FAMEs were produced in 10 days. Quantification of key proteins and metabolites, together with constructs over-expressing SAM synthetase (MetK), indicated that 'UcFatB1, MetK, and DmJHAMT were the main factors limiting pathway flux. In order to solve the latter limitation, two reconstructed ancestral sequences of DmJHAMT were also tried, resulting in strains showing a broader methyl ester chain-length profile in comparison to the native DmJHAMT. Altogether, this work demonstrates a promising pathway for direct sunlight-driven conversion of CO2 into excreted FAME.
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Biocombustibles , Ácidos Grasos , Ingeniería Metabólica , Microorganismos Modificados Genéticamente , Synechocystis , Esterificación , Ácidos Grasos/biosíntesis , Ácidos Grasos/genética , Metanol , Microorganismos Modificados Genéticamente/genética , Microorganismos Modificados Genéticamente/crecimiento & desarrollo , Synechocystis/genética , Synechocystis/crecimiento & desarrolloRESUMEN
Microalgal isolates obtained from stream water and wastewater treatment plant were examined to select a suitable microalgal species capable of simultaneously removing nutrient and producing biofuel. Ten isolates were identified using internal transcribed spacer (ITS) region sequencing analysis and were determined to be green microalgae, belonging to phylum Chlorophyta. The highest nutrient removal rates of 8.1 mg-T-N/L-d and 1.6 mg-T-P/L-d were achieved by Chlorella sorokiniana UTEX 1810 under photo-autotrophic cultivation conditions. Fatty acid methyl ester (FAME) composition analysis was conducted to estimate biofuel quality using gas chromatography with mass spectrometry on the basis of the lipid content extracted from microalgal cell. The composition of FAME is mainly composed of palmitic acid (C16:0), stearic acid (C18:0), linoleic acid (C18:2), and heneicosanoic acid (C21:0). These results suggest that C. sorokiniana UTEX 1810 is a promising candidate for simultaneous removal of nutrient and biofuel production from wastewater.