RESUMEN

Primary microRNA (pri-miRNA) transcripts are processed by the Microprocessor, a protein complex that includes the ribonuclease Drosha and its RNA binding partner DGCR8/Pasha. We developed a live, whole animal, fluorescence-based sensor that reliably monitors pri-miRNA processing with high sensitivity in C. elegans. Through a forward genetic selection for alleles that desilence the sensor, we identified a mutation in the conserved G residue adjacent to the namesake W residue of Pasha's WW domain. Using genome editing we also mutated the W residue and reveal that both the G and W residue are required for dimerization of Pasha and proper assembly of the Microprocessor. Surprisingly, we find that the WW domain also facilitates nuclear localization of Pasha, which in turn promotes nuclear import or retention of Drosha. Furthermore, depletion of Pasha or Drosha causes both components of the Microprocessor to mislocalize to the cytoplasm. Thus, Pasha and Drosha mutually regulate each other's spatial expression in C. elegans.

RESUMEN

Spectrally-resolved imaging provides a spectrum for each pixel of an image that, in the mid-infrared, can enable its chemical composition to be mapped by exploiting the correlation between spectroscopic features and specific molecular groups. The compatibility of Fourier-transform interferometry with full-field imaging makes it the spectroscopic method of choice, but Nyquist-limited fringe sampling restricts the increments of the interferometer arm length to no more than a few microns, making the acquisition time-consuming. Here, we demonstrate a compressive hyperspectral imaging strategy that combines non-uniform sampling and a smoothness-promoting prior to acquire data at 15% of the Nyquist rate, providing a significant acquisition-rate improvement over state-of-the-art techniques. By illuminating test objects with a sequence of suitably designed light spectra, we demonstrate compressive hyperspectral imaging across the 700-1400 cm-1 region in transmission mode. A post-processing analysis of the resulting hyperspectral images shows the potential of the method for efficient non-destructive classification of different materials on painted cultural heritage.

RESUMEN

The remediation of metal and heavy metal contaminants from water ecosystems is a long-standing problem in the field of water management. The development of efficient, cost effective, and environmentally friendly natural polymer-based adsorbents is reported here. Magnetic chitosan (CS) and carboxymethylchitosan (CMC) nanocomposites have been synthesized by a simple one-step chemical coprecipitation method. The nanoparticles were assessed for the removal of Pb2+, Cu2+, and Zn2+ ions from aqueous solution. Kinetic and thermodynamic models were used to describe and understand the adsorption process of the ions onto the nanomaterials. The interactions between the ions and the biopolymer-based composites are reversible, which means that the nanoparticles can be regenerated in weakly acidic or EDTA containing solution without losing their activity and stability for water cleanup applications.

RESUMEN

Prevention of mineral fouling, known as scale, is a long-standing problem in a wide variety of industrial applications, such as oil production, water treatment, and many others. The build-up of inorganic scale such as calcium carbonate on surfaces and facilities is undesirable as it can result in safety risks and associated flow assurance issues. To date the overwhelming amount of research has mainly focused on chemical inhibition of scale bulk precipitation and little attention has been paid to deposition onto surfaces. The development of novel more environmentally-friendly strategies to control mineral fouling will most probably necessitate a multifunctional approach including surface engineering. In this study, we demonstrate that liquid infused porous surfaces provide an appealing strategy for surface modification to reduce mineral scale deposition. Microporous polypyrrole (PPy) coatings were fabricated onto stainless steel substrates by electrodeposition in potentiostatic mode. Subsequent infusion of low surface energy lubricants (fluorinated oil Fluorinert FC-70 and ionic liquid 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIm)) into the porous coatings results in liquid-repellent slippery surfaces. To assess their ability to reduce surface scaling the coatings were subjected to a calcium carbonate scaling environment and the scale on the surface was quantified using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). PPy surfaces infused with BMIm (and Fluorinert to a lesser extent) exhibit remarkable antifouling properties with the calcium carbonate deposition reduced by 18 times in comparison to untreated stainless steel. These scaling tests suggest a correlation between the stability of the liquid infused surfaces in artificial brines and fouling reduction efficiency. The current work shows the great potential of such novel coatings for the management of mineral scale fouling.

RESUMEN

DFT calculations were performed on the thermal reactions of chlorpropham 1, a carbamate pesticide and plant growth regulator frequently used in the storage of potatoes. At the conditions normally used in applying 1 (injection of a methanolic solution of 1 into a hot air stream, T ≈ 500°C), both ester pyrolysis of 1 and a methanol-or water-catalysed isocyanate cleavage are expected to proceed rapidly (lifetime of 1 less than a second). In both reactions, the final reaction product will be toxic and carcinogenic m-chloroaniline 2. Matrix-isolation experiments indicate that 1 undergoes thermal decay at temperatures as low as 250°C. Up to temperatures of ca. 500°C, formation of m-chlorophenylisocyanate 4 and isopropanol was the predominant reaction observed, while formation of propene, CO(2), and m-chloroaniline 2 was the most important reaction channel at higher pyrolysis temperatures. m-Chlorophenyl carbamic acid 3 could not be observed. The results indicate that at lower temperatures, 1 decays exclusively via isocyanate cleavage of 1, provided that traces of catalytic water or other protic compounds are present. At higher temperatures, ester cleavage of 1 becomes competitive and outweighs the isocyanate cleavage by a factor of ca. 10:1.

Asunto(s)

Clorprofam/química , Herbicidas/química , Calor , Espectrometría de Masas

RESUMEN

Chlorpropham (CIPC) was introduced in 1951 and is a primary N-phenyl carbamate belonging to a group of pesticides known as carbamates which are estimated to account for 11% of the total insecticide sales worldwide. They were considered less toxic than organochlorines due to their easier breakdown but, subsequent concerns regarding the environmental impact and their breakdown products have shown them to be environmental toxins and toxic and/or carcinogenic for humans. CIPC is used in growing crops to control weeds and also as a sprout suppressant on crops during long-term storage and while its degradation has been studied and rates quoted these vary greatly. Here published rates of degradation by hydrolysis, biolysis, photolysis and thermal processes are reviewed as well as data on partitioning in air, water and soil. In addition the details of the experimental procedures are reviewed and compared showing how the half-lives and partitioning coefficients have been calculated leading to an understanding of how such vastly different values are achieved. The legislation regarding the use of CIPC and its maximum residue level is also discussed particularly in reference to recent European Commission (EC) legislation. In view of the fact that analytical data on the breakdown of CIPC play an important role in decision-making by regulatory agencies, the authors feel that it is time for an up-to-date review of the data available, including very recent developments in methodology.

Asunto(s)

Clorprofam/química , Monitoreo del Ambiente/métodos , Contaminantes Ambientales/química , Insecticidas/química , Biodegradación Ambiental , Clorprofam/análisis , Contaminantes Ambientales/análisis , Semivida , Humanos , Hidrólisis , Insecticidas/análisis , Modelos Químicos , Fotólisis , Volatilización

RESUMEN

The reaction of triplet benzophenone with benzene and diphenyl ether has been studied by density functional theory. Quenching of the triplet ketone is predicted to occur by addition of the carbonyl oxygen to the arene chromophores. The reaction is accompanied by a significant degree of charge transfer. In case of the reaction of triplet benzophenone with diphenyl ether (DPE), addition is predicted to occur preferentially at the ortho position of the DPE molecule. Addition to the ipso-position of DPE, which provides a pathway for formation of the phenoxy radical, is predicted to occur as a minor reaction pathway.

Asunto(s)

Benceno/química , Benzofenonas/química , Simulación de Dinámica Molecular , Éteres Fenílicos/química , Estructura Molecular

RESUMEN

Optically clear, surfactant loaded poly (2-hydroxyethyl methacrylate) (pHEMA) hydrogels can be used to prevent fouling on optical windows of marine underwater sensors. To act successfully in this capacity, hydrogels need to prevent both microfouling and macrofouling. Panel trials were conducted using four different materials: unloaded hydrogels, hydrogels containing either benzalkonium chloride (BAC) or dicocodimethylammonium chloride (Arquad 2C-75) and PMMA coupons. Three panels were deployed at staggered intervals (2, 4 and 6 weeks) before the main settlement season of Semibalanus balanoides and Mytilus edulis in the Firth of Clyde, Scotland. Panels were left for a total period of 10, 12 and 14 weeks respectively. Results showed that no sample completely resisted fouling, but Arquad 2C-75 hydrogels were extremely effective at preventing both microfouling and macrofouling. The most heavily fouled materials were unloaded hydrogels and PMMA, despite differences in initial hydrophilicities. Arquad 2C-75 hydrogels were equally effective at preventing larval settlement, for up to 14 weeks.

Asunto(s)

Compuestos de Benzalconio/química , Compuestos de Benzalconio/farmacología , Hidrogeles/química , Compuestos de Amonio Cuaternario/química , Compuestos de Amonio Cuaternario/farmacología , Animales , Larva/efectos de los fármacos , Larva/fisiología , Mytilus/efectos de los fármacos , Mytilus/crecimiento & desarrollo , Análisis Espectral , Thoracica/efectos de los fármacos , Thoracica/crecimiento & desarrollo

RESUMEN

We have analysed the expression of a truncated variant presenilin 2 protein (PS2V) in frontal cortex from subjects with Alzheimer's disease (AD) and age-matched controls, and compared these results with cortex from bipolar disorder (BP), schizophrenia (SZ) and controls in a second brain bank collection. PS2V protein was detected as a 14 kDa species with antibodies directed to the PS2 N-terminal region and to the new C-terminus created by alternative transcription. PS2V protein levels were significantly increased by two-fold in AD cortex, as compared to age-matched controls. In tissue from the second collection, levels of PS2V were markedly elevated in some BP and SZ cases, but there was no overall difference between diagnostic groups. Our findings support previous evidence for increased expression of this variant PS2 isoform in sporadic AD and suggest this isoform may contribute to neurodegeneration.

Asunto(s)

Empalme Alternativo , Enfermedad de Alzheimer/metabolismo , Trastorno Bipolar/metabolismo , Corteza Cerebral/metabolismo , Proteínas de la Membrana/metabolismo , Esquizofrenia/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/genética , Trastorno Bipolar/genética , Western Blotting/métodos , Línea Celular Tumoral , Clonación Molecular/métodos , Síndrome de Down/genética , Femenino , Variación Genética , Humanos , Inmunoprecipitación/métodos , Masculino , Proteínas de la Membrana/genética , Persona de Mediana Edad , Neuroblastoma , Cambios Post Mortem , Presenilina-2 , ARN Mensajero/biosíntesis , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Esquizofrenia/genética

RESUMEN

We have analyzed the expression of Alzheimer's disease-associated presenilin 1 (PS1) in various neurodegenerative disorders. Western blotting identified PS1 N- and C-terminal fragments similarly in the cortex of controls, Parkinson, Huntington and schizophrenia subjects. Additional PS1 immunoreactive species of 42 and 46 kDa were present in six out of seven cases of sporadic frontotemporal dementia (FTD) and these were particularly prominent in two cases. RT-PCR analysis using nested primers showed the presence of PS1 gene products with deletions within the exon 4-8 region. Our results suggest that alternative transcription of PS1 may be associated with FTD.

Asunto(s)

Empalme Alternativo/genética , Corteza Cerebral/metabolismo , Demencia/genética , Demencia/metabolismo , Proteínas de la Membrana/genética , Mutación/genética , Neuronas/metabolismo , ARN Mensajero/genética , Adulto , Anciano , Secuencia de Aminoácidos , Secuencia de Bases , Western Blotting , Corteza Cerebral/patología , Corteza Cerebral/fisiopatología , Demencia/fisiopatología , Exones/genética , Eliminación de Gen , Humanos , Proteínas de la Membrana/metabolismo , Persona de Mediana Edad , Neuronas/patología , Presenilina-1 , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Estructura Terciaria de Proteína/genética

RESUMEN

We have analyzed the expression of Alzheimer's disease-associated presenilin 1 (PS1) in various neurodegenerative disorders. Western blotting identified PS1 N- and C-terminal fragments similarly in the cortex of controls, Parkinson, Huntington and schizophrenia subjects. Additional PS1 immunoreactive species of 42 and 46 kDa were present in six out of seven cases of sporadic frontotemporal dementia (FTD) and these were particularly prominent in two cases. RT-PCR analysis using nested primers showed the presence of PS1 gene products with deletions within the exon 4-8 region. Our results suggest that alternative transcription of PS1 may be associated with FTD.

Asunto(s)

Empalme Alternativo/genética , Demencia/genética , Proteínas de la Membrana/genética , Encéfalo/metabolismo , Encéfalo/patología , Demencia/metabolismo , Demencia/patología , Exones/genética , Eliminación de Gen , Perfilación de la Expresión Génica/métodos , Perfilación de la Expresión Génica/estadística & datos numéricos , Humanos , Proteínas de la Membrana/biosíntesis , Presenilina-1