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1.
Environ Monit Assess ; 195(10): 1203, 2023 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-37702824

RESUMEN

The spatial distribution of total petroleum hydrocarbons (TPH) were analysed in the seawater and sediment samples collected from 27 locations along the Southeast coast of India. A first-time assessment was carried out on the distribution of TPH in both water and sediments for the entire coastline of Tamil Nadu. The concentration of TPH in seawater showed large spatial variation ranging from below detection level (BDL) to 47.5 µg/L and 0.01 to 53.12 µg/L in the surface and bottom waters, respectively. TPH levels exceeded the regulatory limits specified by FAO, China's Marine Monitoring Standards and the European Community in the seawater samples of Thoothukudi harbour (S2 station). The results showed that seawaters of southern stations were comparatively more polluted with TPH. TPH values in sediment were between 2.33 and 30.07 µg/g, and their levels remained below the Marine Sediment Quality Standard (500 µg/g). The spatial profile of TPH in sediments were contrasting to that observed for seawater. Higher TPH values were observed in sediments of the northern region than southern. TPH contents are strongly correlated with clay (R2 = 0.776; P < 0.001) and silt (R2 = 0.648; P < 0.001); conversely, there is a significant negative correlation between TPH and sand (R2 = 0.753; P < 0.001). ANOVA analysis demonstrated a significant difference (F = 11.75; p < 0.01) between the TPH concentrations of water and sediments. Non-metric multidimensional scaling (nMDS) was performed to determine the similarity among sampling stations that formed five crusted groups. Sediment along the southeast coast can be categorised as slightly polluted with respect to TPH as per the ATSDR standards.


Asunto(s)
Monitoreo del Ambiente , Petróleo , India , Agua de Mar , Agua , Hidrocarburos
2.
Ecotoxicol Environ Saf ; 208: 111612, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33396132

RESUMEN

Water quality standards are essential for regulation of contaminants in marine environment. Seawater quality criteria (SWQC) for arsenic (As), cadmium (Cd) and lead (Pb) have not been developed for India. The aim of this study is to derive the SWQC for the metals based on Species Sensitivity Distribution (SSD). Eight species of sensitive marine organisms belonging to five phyla were assessed for their sensitivity to toxicity of As, Cd and Pb. Median effective concentrations (EC50) and Median Lethal Concentrations (LC50) were derived from the acute toxicity bio-assays. No Observed Effect Concentrations (NOEC), Lowest Observed Effect Concentrations (LOEC) and chronic values were derived from chronic toxicity bio-assays. Diatoms were more sensitive to As with 96 h EC50 of 0.1 mg/l and copepods were more sensitive to Cd and Pb with 96 h EC50 of 0.019 mg/l and 0.05 mg/l respectively. Estimated NOECs ranged from 4.87 to 21.55 µg/l of As, 1.0 to 120 µg/l of Cd and 5.67 to 91.67 µg/l of Pb. Similarly, chronic values (µg/l) were in the range of 6.71-26.1, 1.38-170, and 7.67-91.67 of As, Cd and Pb respectively. The Criterion Maximum Concentration (CMC), Criterion Continuous Concentration (CCC) and Predicted No Effect Concentration (PNEC) values were prescribed as SWQC. The CMC (µg/l) of 19, 1.7 and 17 for As, Cd, and Pb were derived respectively for acute exposure during accidental marine outfalls. The CCC (µg/l) for As was 4.6, 1.1 for Cd and 5.9 for Pb are recommended as SWQC for protection of 95% of marine organisms. PNEC (µg/l) of 3.8 for As, 0.92 for Cd and 4.3 for Pb are suggested for highly disturbed ecosystems, shell fishing and mariculture uses of water bodies. These values are recommended as a baseline for site specific water quality criteria for the coastal waters of the country.


Asunto(s)
Organismos Acuáticos/efectos de los fármacos , Arsénico/toxicidad , Cadmio/toxicidad , Plomo/toxicidad , Agua de Mar/química , Contaminantes Químicos del Agua/toxicidad , Calidad del Agua/normas , Animales , Arsénico/análisis , Cadmio/análisis , Copépodos/efectos de los fármacos , Diatomeas/efectos de los fármacos , Ecosistema , India , Plomo/análisis , Dosificación Letal Mediana , Especificidad de la Especie , Contaminantes Químicos del Agua/análisis
3.
Arch Virol ; 164(2): 497-507, 2019 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-30430265

RESUMEN

The capsids of viruses have a high degree of symmetry. Therefore, virus nanoparticles (VNPs) can be programmed to display many imaging agents precisely. Plant VNPs are biocompatible, biodegradable and non-infectious to mammals. We have carried out bioconjugation of sesbania mosaic virus (SeMV), a well characterized plant virus, with fluorophores using reactive lysine-N-hydroxysuccinimide ester and cysteine-maleimide chemistries. Monitoring of cellular internalization of labelled SeMV nanoparticles (NPs) by confocal microscopy and flow cytometry showed that the particles have a natural preference for entry into MDA-MB-231 (breast cancer) cells, although they could also enter various other cell lines. The fluorescence of SeMV NPs labelled via the cysteines with Cy5.5 dye was found to be more stable and was detectable with greater sensitivity than that of particles labelled via the lysines with Alexa Fluor. Live-cell imaging using SeMV internally labelled with Cy5.5 showed that it could bind to MDA-MB-231 cells in less than 5 minutes and enter the cells within 15 minutes. The particles undergo endolysosomal degradation by 6 h as evidenced by their co-localization with LAMP-1. Far-western blot analysis with a HeLa cell membrane protein fraction showed that SeMV interacts with 54-, 35- and 33-kDa proteins, which were identified by mass spectrometry as vimentin, voltage-dependent anion-selective channel protein (VDAC1), and annexin A2 isoform 2 (ANXA2), respectively, suggesting that the particles may bind and enter the cell through these proteins. The results presented here demonstrate that the SeMV NPs provide a new platform technology that could be used to develop in vivo imaging and targeted drug delivery agents for cancer diagnosis and therapy.


Asunto(s)
Nanopartículas/química , Virus de Plantas/química , Línea Celular Tumoral , Citometría de Flujo , Fluorescencia , Colorantes Fluorescentes/química , Humanos , Lisosomas/metabolismo , Microscopía Confocal , Imagen Molecular/instrumentación , Nanopartículas/metabolismo , Virus de Plantas/fisiología
4.
J Struct Biol ; 202(2): 118-128, 2018 05.
Artículo en Inglés | MEDLINE | ID: mdl-29294403

RESUMEN

Cellular metabolism of amino acids is controlled by a large number of pyridoxal 5'-phosphate (PLP) dependent enzymes. Diaminopropionate ammonia lyase (DAPAL), a fold type II PLP-dependent enzyme, degrades both the D and L forms of diaminopropionic acid (DAP) to pyruvate and ammonia. Earlier studies on the Escherichia coli DAPAL (EcDAPAL) had suggested that a disulfide bond located close to the active site may be crucial for maintaining the geometry of the substrate entry channel and the active site. In order to obtain further insights into the catalytic properties of DAPAL, structural and functional studies on Salmonella typhimurium DAPAL (StDAPAL) were initiated. The three-dimensional X-ray crystal structure of StDAPAL was determined at 2.5 Šresolution. As expected, the polypeptide fold and dimeric organization of StDAPAL is similar to those of EcDAPAL. A phosphate group was located in the active site of StDAPAL and expulsion of this phosphate is probably essential to bring Asp125 to a conformation suitable for proton abstraction from the substrate (D-DAP). The unique disulfide bond of EcDAPAL was absent in StDAPAL, although the enzyme displayed comparable catalytic activity. Site directed mutagenesis of the cysteine residues involved in disulfide bond formation in EcDAPAL followed by functional and biophysical studies further confirmed that the disulfide bond is not necessary either for substrate binding or for catalysis. The activity of StDAPAL but not EcDAPAL was enhanced by monovalent cations suggesting subtle differences in the active site geometries of these two closely related enzymes.


Asunto(s)
Amoníaco-Liasas/química , Escherichia coli/enzimología , Salmonella typhimurium/enzimología , Relación Estructura-Actividad , Amoníaco-Liasas/genética , Catálisis , Dominio Catalítico/genética , Cristalografía por Rayos X , Cinética , Mutagénesis Sitio-Dirigida , Pliegue de Proteína , Especificidad por Sustrato
5.
Biochem Biophys Res Commun ; 495(1): 982-987, 2018 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-29154992

RESUMEN

Latent tuberculosis (TB) is the main hurdle in reaching the goal of "Stop TB 2050". Tuberculin skin and Interferon-gamma release assay tests used currently for the diagnosis of TB infection cannot distinguish between active disease and latent tuberculosis infection (LTBI) and hence new and sensitive protein markers need to be identified for the diagnosis. A protein Rv3716c from Mycobacterium tuberculosis (MtbRv3716c) has been identified as a potential surrogate marker for the diagnosis of LTBI. Here, we present characterization of MtbRv3716c (∼13 kDa) using both biophysical and X-Ray crystallographic methods. EMSA study showed that MtbRv3716c binds to double stranded DNA. X-ray diffraction data collected on a crystal of MtbRv3716c at 1.9 Å resolution was used for structure determination using the molecular replacement method. Significant electron density was not observed for the N-terminal 21 and C-terminal 41 residues in the final electron density map. The C- terminal disordered region is proline rich and displays characteristics of intrinsically disordered proteins. Although the crystal asymmetric unit contained a protomer, a tight dimer could be generated by the application of the crystal two-fold symmetry parallel to the b axis. Packing of dimers in the crystal is mediated by a cadmium ion (Cd2+) occurring at the interface of two dimers. Molecular packing analysis reveals large cavities that are probably occupied by the disordered segments of the N- and C-termini. Structural comparison with other homologous hypothetical DNA binding proteins (PDB codes: 1PUG, 1YBX) highlights structural features that might be significant for DNA binding.


Asunto(s)
Proteínas Bacterianas/química , Proteínas Bacterianas/ultraestructura , Tuberculosis Latente/microbiología , Mycobacterium tuberculosis/metabolismo , Secuencia de Aminoácidos , Simulación por Computador , Modelos Químicos , Modelos Moleculares , Conformación Proteica
6.
Biochem Biophys Res Commun ; 490(4): 1362-1368, 2017 09 02.
Artículo en Inglés | MEDLINE | ID: mdl-28694189

RESUMEN

Enteric pathogens such as Salmonella typhimurium colonize the human gut in spite of the lethal acidic pH environment (pH < 2.5) due to the activation of inducible acid tolerance response (ATR) systems. The pyridoxal 5'-phosphate (PLP)-dependent enzyme, biodegradative arginine decarboxylase (ADC, encoded by AdiA), is a component of an ATR system. The enzyme consumes a cytoplasmic proton in the process of arginine degradation to agmatine. Arginine-agmatine antiporter (AdiC) exchanges the product agmatine for arginine. In this manuscript, we describe the structure of Salmonella typhimurium ADC (StADC). The decameric structure assembled from five dimers related by a non crystallographic 5-fold symmetry represents the first apo-form of the enzyme. The structure suggests that PLP-binding is not a prerequisite for oligomerization. Comparison with E. coli ADC reveals that PLP-binding is accompanied by the movement and ordering of two loops (residues 150-159 and 191-197) and a few active site residues such as His256 and Lys257. A number of residues important for substrate binding are disordered in the apo-StADC structure indicating that PLP binding is important for substrate binding. Unlike the interactions between 5-fold related protomers, interactions that stabilize the dimeric structure are not pH dependent.


Asunto(s)
Arginina/química , Proteínas Bacterianas/química , Carboxiliasas/química , Fosfato de Piridoxal/química , Salmonella typhimurium/química , Secuencias de Aminoácidos , Arginina/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Sitios de Unión , Carboxiliasas/genética , Carboxiliasas/metabolismo , Dominio Catalítico , Clonación Molecular , Cristalografía por Rayos X , Escherichia coli/genética , Escherichia coli/metabolismo , Expresión Génica , Concentración de Iones de Hidrógeno , Cinética , Modelos Moleculares , Unión Proteica , Conformación Proteica en Hélice alfa , Conformación Proteica en Lámina beta , Dominios y Motivos de Interacción de Proteínas , Multimerización de Proteína , Fosfato de Piridoxal/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Salmonella typhimurium/enzimología , Especificidad por Sustrato
7.
J Struct Biol ; 193(2): 95-105, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26706030

RESUMEN

Tobacco streak virus (TSV), the type member of Ilarvirus genus, is a major plant pathogen. TSV purified from infected plants consists of a ss-RNA genome encapsidated in spheroidal particles with diameters of 27, 30 and 33nm constructed from multiple copies of a single species of coat protein (CP) subunits. Apart from protecting the viral genome, CPs of ilarviruses play several key roles in the life cycle of these viruses. Unlike the related bromo and cucumoviruses, ilarvirus particles are labile and pleomorphic, which has posed difficulties in their crystallization and structure determination. In the current study, a truncated TSV-CP was crystallized in two distinct forms and their structures were determined at resolutions of 2.4Å and 2.1Å, respectively. The core of TSV CP was found to possess the canonical ß-barrel jelly roll tertiary structure observed in several other viruses. Dimers of CP with swapped C-terminal arms (C-arm) were observed in both the crystal forms. The C-arm was found to be flexible and is likely to be responsible for the polymorphic and pleomorphic nature of TSV capsids. Consistent with this observation, mutations in the hinge region of the C-arm that reduce the flexibility resulted in the formation of more uniform particles. TSV CP was found to be structurally similar to that of Alfalfa mosaic virus (AMV) accounting for similar mechanism of genome activation in alfamo and ilar viruses. This communication represents the first report on the structure of the CP from an ilarvirus.


Asunto(s)
Proteínas de la Cápside/química , Ilarvirus/química , Virus del Mosaico de la Alfalfa/química , Virus del Mosaico de la Alfalfa/fisiología , Proteínas de la Cápside/genética , Proteínas de la Cápside/aislamiento & purificación , Proteínas de la Cápside/metabolismo , Simulación por Computador , Cristalografía por Rayos X , Ilarvirus/fisiología , Modelos Moleculares , Conformación Proteica , Multimerización de Proteína
8.
Arch Virol ; 161(10): 2673-81, 2016 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-27395369

RESUMEN

Sesbania mosaic virus (SeMV), a 30-nm spherical plant sobemovirus, is suitable for developing functionalized nanoparticles for biomedical applications. However, the in vivo behavior of SeMV and the clinical impact following its delivery via the oral or intravenous route are not known. To address this question, we examined the biodistribution, toxicity and histopathological changes in SeMV treated mice. No toxic effects were observed in mice administered high doses (100 mg and 200 mg per kg body weight orally or 40 mg and 80 mg per kg body weight intravenously) of SeMV, and they were found to be normal. Analysis of fecal sample showed that SeMV was cleared in 16 h when 20 mg of the virus per kg body weight was administered orally. RT-PCR analysis of blood samples showed that SeMV was present up to 72 h in mice inoculated either intravenously (8 mg/kg body weight) or orally (20 mg/kg body weight). Further, SeMV was found to be localized up to 72 h in spleen and liver tissues of intravenously inoculated mice only. Biochemical and hematological parameters were found to be normal at 6 and 72 h after administration of SeMV. Furthermore, no noticeable changes were observed in histological sections of brain, liver, spleen, lungs and kidney tissue samples collected at 6 and 72 h from SeMV administered mice when compared to control mice. Thus, SeMV appears to be a safe and non-toxic platform that can be tailored as a nanocarrier for in vivo biomedical applications.


Asunto(s)
Nanopartículas/metabolismo , Nanopartículas/toxicidad , Virus de Plantas/metabolismo , Virus ARN/metabolismo , Sesbania/virología , Administración Intravenosa , Administración Oral , Animales , Sangre/virología , Heces/virología , Femenino , Histocitoquímica , Riñón/patología , Riñón/virología , Hígado/patología , Hígado/virología , Ratones , Nanopartículas/administración & dosificación , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Bazo/patología , Bazo/virología
9.
J Struct Biol ; 189(3): 238-50, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-25600413

RESUMEN

In many organisms "Universal Stress Proteins" (USPs) are induced in response to a variety of environmental stresses. Here we report the structures of two USPs, YnaF and YdaA from Salmonella typhimurium determined at 1.8Å and 2.4Å resolutions, respectively. YnaF consists of a single USP domain and forms a tetrameric organization stabilized by interactions mediated through chloride ions. YdaA is a larger protein consisting of two tandem USP domains. Two protomers of YdaA associate to form a structure similar to the YnaF tetramer. YdaA showed ATPase activity and an ATP binding motif G-2X-G-9X-G(S/T/N) was found in its C-terminal domain. The residues corresponding to this motif were not conserved in YnaF although YnaF could bind ATP. However, unlike YdaA, YnaF did not hydrolyse ATP in vitro. Disruption of interactions mediated through chloride ions by selected mutations converted YnaF into an ATPase. Residues that might be important for ATP hydrolysis could be identified by comparing the active sites of native and mutant structures. Only the C-terminal domain of YdaA appears to be involved in ATP hydrolysis. The structurally similar N-terminal domain was found to bind a zinc ion near the segment equivalent to the phosphate binding loop of the C-terminal domain. Mass spectrometric analysis showed that YdaA might bind a ligand of approximate molecular weight 800daltons. Structural comparisons suggest that the ligand, probably related to an intermediate in lipid A biosynthesis, might bind at a site close to the zinc ion. Therefore, the N-terminal domain of YdaA binds zinc and might play a role in lipid metabolism. Thus, USPs appear to perform several distinct functions such as ATP hydrolysis, altering membrane properties and chloride sensing.


Asunto(s)
Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Salmonella typhimurium/química , Adenosina Trifosfato/metabolismo , Proteínas Bacterianas/genética , Sitios de Unión , Dominio Catalítico , Cloruros/metabolismo , Cristalografía por Rayos X , Hidrólisis , Modelos Moleculares , Mutación , Conformación Proteica , Estructura Terciaria de Proteína , Salmonella typhimurium/fisiología , Estrés Fisiológico , Zinc/metabolismo
10.
Acta Crystallogr D Biol Crystallogr ; 71(Pt 9): 1812-23, 2015 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-26327371

RESUMEN

The survival protein SurE from Salmonella typhimurium (StSurE) is a dimeric protein that functions as a phosphatase. SurE dimers are formed by the swapping of a loop with a pair of ß-strands and a C-terminal helix between two protomers. In a previous study, the Asp230 and His234 residues were mutated to Ala to abolish a hydrogen bond that was thought to be crucial for C-terminal helix swapping. These mutations led to functionally inactive and distorted dimers in which the two protomers were related by a rotation of 167°. New salt bridges involving Glu112 were observed in the dimeric interface of the H234A and D230A/H234A mutants. To explore the role of these salt bridges in the stability of the distorted structure, E112A, E112A/D230A, E112A/H234A, E112A/D230A/H234A, R179L/H180A/H234A and E112A/R179L/H180A/H234A mutants were constructed. X-ray crystal structures of the E112A, E112A/H234A and E112A/D230A mutants could be determined. The dimeric structures of the E112A and E112A/H234A mutants were similar to that of native SurE, while the E112A/D230A mutant had a residual rotation of 11° between the B chains upon superposition of the A chains of the mutant and native dimers. The native dimeric structure was nearly restored in the E112A/H234A mutant, suggesting that the new salt bridge observed in the H234A and D230A/H234A mutants was indeed responsible for the stability of their distorted structures. Catalytic activity was also restored in these mutants, implying that appropriate dimeric organization is necessary for the activity of SurE.


Asunto(s)
Proteínas Bacterianas/química , Salmonella typhimurium/química , Proteínas Bacterianas/genética , Cristalografía por Rayos X , Dimerización , Modelos Moleculares , Mutación , Conformación Proteica
11.
Acta Crystallogr D Biol Crystallogr ; 71(Pt 12): 2479-93, 2015 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-26627655

RESUMEN

Thiolases catalyze the degradation and synthesis of 3-ketoacyl-CoA molecules. Here, the crystal structures of a T1-like thiolase (MSM-13 thiolase) from Mycobacterium smegmatis in apo and liganded forms are described. Systematic comparisons of six crystallographically independent unliganded MSM-13 thiolase tetramers (dimers of tight dimers) from three different crystal forms revealed that the two tight dimers are connected to a rigid tetramerization domain via flexible hinge regions, generating an asymmetric tetramer. In the liganded structure, CoA is bound to those subunits that are rotated towards the tip of the tetramerization loop of the opposing dimer, suggesting that this loop is important for substrate binding. The hinge regions responsible for this rotation occur near Val123 and Arg149. The Lα1-covering loop-Lα2 region, together with the Nß2-Nα2 loop of the adjacent subunit, defines a specificity pocket that is larger and more polar than those of other tetrameric thiolases, suggesting that MSM-13 thiolase has a distinct substrate specificity. Consistent with this finding, only residual activity was detected with acetoacetyl-CoA as the substrate in the degradative direction. No activity was observed with acetyl-CoA in the synthetic direction. Structural comparisons with other well characterized thiolases suggest that MSM-13 thiolase is probably a degradative thiolase that is specific for 3-ketoacyl-CoA molecules with polar, bulky acyl chains.


Asunto(s)
Acetil-CoA C-Aciltransferasa/química , Proteínas Bacterianas/química , Mitocondrias/química , Proteínas Mitocondriales/química , Mycobacterium smegmatis/química , Subunidades de Proteína/química , Acetil-CoA C-Aciltransferasa/genética , Acetil-CoA C-Aciltransferasa/metabolismo , Secuencia de Aminoácidos , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Dominio Catalítico , Cristalografía por Rayos X , Escherichia coli/genética , Escherichia coli/metabolismo , Expresión Génica , Cinética , Mitocondrias/enzimología , Proteínas Mitocondriales/genética , Proteínas Mitocondriales/metabolismo , Modelos Moleculares , Datos de Secuencia Molecular , Mycobacterium smegmatis/clasificación , Mycobacterium smegmatis/enzimología , Filogenia , Unión Proteica , Multimerización de Proteína , Estructura Secundaria de Proteína , Subunidades de Proteína/genética , Subunidades de Proteína/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Alineación de Secuencia , Especificidad por Sustrato
12.
J Environ Manage ; 148: 91-100, 2015 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-24680540

RESUMEN

Land cover (LC) is one of the most important and easily detectable indicators of change in ecosystem services and livelihood support systems. This paper describes the decadal dynamics in LC changes at national and sub-national level in Bhutan derived by applying object-based image analysis (OBIA) techniques to 1990, 2000, and 2010 Landsat (30 m spatial resolution) data. Ten LC classes were defined in order to give a harmonized legend land cover classification system (LCCS). An accuracy of 83% was achieved for LC-2010 as determined from spot analysis using very high resolution satellite data from Google Earth Pro and limited field verification. At the national level, overall forest increased from 25,558 to 26,732 km(2) between 1990 and 2010, equivalent to an average annual growth rate of 59 km(2)/year (0.22%). There was an overall reduction in grassland, shrubland, and barren area, but the observations were highly dependent on time of acquisition of the satellite data and climatic conditions. The greatest change from non-forest to forest (277 km(2)) was in Bumthang district, followed by Wangdue Phodrang and Trashigang, with the least (1 km(2)) in Tsirang. Forest and scrub forest covers close to 75% of the land area of Bhutan, and just over half of the total area (51%) has some form of conservation status. This study indicates that numerous applications and analyses can be carried out to support improved land cover and land use (LCLU) management. It will be possible to replicate this study in the future as comparable new satellite data is scheduled to become available.


Asunto(s)
Conservación de los Recursos Naturales , Monitoreo del Ambiente/métodos , Árboles , Urbanización/tendencias , Bután , Ecosistema , Sistemas de Información Geográfica , Humanos , Tecnología de Sensores Remotos
13.
J Environ Manage ; 148: 82-90, 2015 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-25181944

RESUMEN

Land cover and its change analysis across the Hindu Kush Himalayan (HKH) region is realized as an urgent need to support diverse issues of environmental conservation. This study presents the first and most complete national land cover database of Nepal prepared using public domain Landsat TM data of 2010 and replicable methodology. The study estimated that 39.1% of Nepal is covered by forests and 29.83% by agriculture. Patch and edge forests constituting 23.4% of national forest cover revealed proximate biotic interferences over the forests. Core forests constituted 79.3% of forests of Protected areas where as 63% of area was under core forests in the outside protected area. Physiographic regions wise forest fragmentation analysis revealed specific conservation requirements for productive hill and mid mountain regions. Comparative analysis with Landsat TM based global land cover product showed difference of the order of 30-60% among different land cover classes stressing the need for significant improvements for national level adoption. The online web based land cover validation tool is developed for continual improvement of land cover product. The potential use of the data set for national and regional level sustainable land use planning strategies and meeting several global commitments also highlighted.


Asunto(s)
Conservación de los Recursos Naturales , Monitoreo del Ambiente/estadística & datos numéricos , Bosques , Bases de Datos Factuales/estadística & datos numéricos , Monitoreo del Ambiente/métodos , Humanos , Nepal , Desarrollo de Programa
14.
J Environ Manage ; 161: 433-442, 2015 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-25435154

RESUMEN

The present study aims at analysis of spatial and temporal variability in agricultural land cover during 2005-6 and 2011-12 from an ongoing program of annual land use mapping using multidate Advanced Wide Field Sensor (AWiFS) data aboard Resourcesat-1 and 2. About 640-690 multi-temporal AWiFS quadrant data products per year (depending on cloud cover) were co-registered and radiometrically normalized to prepare state (administrative unit) mosaics. An 18-fold classification was adopted in this project. Rule-based techniques along with maximum-likelihood algorithm were employed to deriving land cover information as well as changes within agricultural land cover classes. The agricultural land cover classes include - kharif (June-October), rabi (November-April), zaid (April-June), area sown more than once, fallow lands and plantation crops. Mean kappa accuracy of these estimates varied from 0.87 to 0.96 for various classes. Standard error of estimate has been computed for each class annually and the area estimates were corrected using standard error of estimate. The corrected estimates range between 99 and 116 Mha for kharif and 77-91 Mha for rabi. The kharif, rabi and net sown area were aggregated at 10 km × 10 km grid on annual basis for entire India and CV was computed at each grid cell using temporal spatially-aggregated area as input. This spatial variability of agricultural land cover classes was analyzed across meteorological zones, irrigated command areas and administrative boundaries. The results indicate that out of various states/meteorological zones, Punjab was consistently cropped during kharif as well as rabi seasons. Out of all irrigated commands, Tawa irrigated command was consistently cropped during rabi season.


Asunto(s)
Agricultura , Productos Agrícolas , Estaciones del Año , Árboles de Decisión , Monitoreo del Ambiente/métodos , India
15.
Biochem J ; 455(1): 119-30, 2013 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-23909465

RESUMEN

Thiolases are essential CoA-dependent enzymes in lipid metabolism. In the present study we report the crystal structures of trypanosomal and leishmanial SCP2 (sterol carrier protein, type-2)-thiolases. Trypanosomatidae cause various widespread devastating (sub)-tropical diseases, for which adequate treatment is lacking. The structures reveal the unique geometry of the active site of this poorly characterized subfamily of thiolases. The key catalytic residues of the classical thiolases are two cysteine residues, functioning as a nucleophile and an acid/base respectively. The latter cysteine residue is part of a CxG motif. Interestingly, this cysteine residue is not conserved in SCP2-thiolases. The structural comparisons now show that in SCP2-thiolases the catalytic acid/base is provided by the cysteine residue of the HDCF motif, which is unique for this thiolase subfamily. This HDCF cysteine residue is spatially equivalent to the CxG cysteine residue of classical thiolases. The HDCF cysteine residue is activated for acid/base catalysis by two main chain NH-atoms, instead of two water molecules, as present in the CxG active site. The structural results have been complemented with enzyme activity data, confirming the importance of the HDCF cysteine residue for catalysis. The data obtained suggest that these trypanosomatid SCP2-thiolases are biosynthetic thiolases. These findings provide promise for drug discovery as biosynthetic thiolases catalyse the first step of the sterol biosynthesis pathway that is essential in several of these parasites.


Asunto(s)
Proteínas Portadoras/química , Coenzima A/química , Cisteína/química , Leishmania mexicana/química , Proteínas Protozoarias/química , Trypanosoma brucei brucei/química , Secuencias de Aminoácidos , Biocatálisis , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Dominio Catalítico , Coenzima A/metabolismo , Cristalografía por Rayos X , Cisteína/genética , Cisteína/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Leishmania mexicana/enzimología , Leishmania mexicana/genética , Modelos Moleculares , Datos de Secuencia Molecular , Unión Proteica , Estructura Cuaternaria de Proteína , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Trypanosoma brucei brucei/enzimología , Trypanosoma brucei brucei/genética
16.
Protist ; 175(2): 126019, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38309038

RESUMEN

The present investigation focused on studying the phylogenetic position of the green Noctiluca endosymbiont, Pedinomonas noctilucae, collected from the Gulf of Mannar, India. In this study, we re-examined the evolutionary position of this endosymbiotic algae using rbcL sequences. The phylogenetic analysis revealed that P. noctilucae is distantly related to the Pedinomonas species, and formed a monophyletic clade with Marsupiomandaceae. Based on the phylogenetic association of endosymbiont with Maruspiomonadales it was concluded that the endosymbiont belongs to an independent genus within the family Marsupiomonadaceae. At the site of the bloom, Noctiluca scintillans was found to exhibit a dense monospecific proliferation, with an average cell density of 27.l88 × 103 cells L-1. The investigation revealed that the green Noctiluca during its senescent phase primarily relied on autotrophic nutrition, which was confirmed by the presence of a high number of trophonts, vegetatively reproducing cells (1.45 × 103 cells L-1) and the absence of food vacuoles.


Asunto(s)
Chlorophyta , Dinoflagelados , Fitoplancton , Filogenia , Evolución Biológica
17.
Mar Pollut Bull ; 204: 116562, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38850757

RESUMEN

The rise of plastics in the 20th century revolutionized modern life but inadvertently exacerbated the marine litter crisis. The proliferation of wastes such as single-use plastics has escalated pollution along the coastline, demanding coordinated, decisive, and unified action. While the absence of specific national marine litter policies is concerning, there is growing recognition of urgency to address this issue. A group of experts and stakeholders was involved through a multi-staged workshop to assess the generated information based on scientific evidence and formulate a framework for the National Marine Litter Policy (NMLP). This paper proposes policy options (4 targets & 20 strategies) to address marine litter pollution, especially plastics, and aims to elucidate the urgency and significance of implementing an NMLP as a comprehensive strategy to combat plastics pollution. Implementing dedicated policies and action plans tailored to the unique challenges faced by each country is a vital step towards sustainable oceans.


Asunto(s)
Política Ambiental , Plásticos , India , Monitoreo del Ambiente , Contaminación del Agua/prevención & control , Contaminación del Agua/estadística & datos numéricos , Residuos
18.
Mar Environ Res ; 199: 106595, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38879903

RESUMEN

A massive fish mortality of the major species, viz., Mugil cephalus, Chanos chanos, and Oreochromis mossambicus, occurred on November 27, 2017 in the Adyar estuary. This catastrophe followed a spell of heavy rainfall and flash floods. A detailed study of water quality parameters (pH, water temperature, salinity, total suspended matter, dissolved oxygen, biochemical oxygen demand, and nutrients) and heavy metals, i.e., chromium (Cr), copper (Cu), cadmium (Cd), nickel (Ni), lead (Pb), and zinc (Zn), in the sediment and fish tissues were analyzed. Pollution indices like the enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), pollution load index (PLI), potential ecological risk index (PERI), and biota sediment accumulation factor (BSAF) were used to measure heavy metals. The pollution indices revealed that metals were significantly enriched in the sediments. The Igeo indicates that there was moderate contamination by Cd (2.27-3.25), whereas CF shows high contamination by Cd (7.22-9.72) and moderate contamination by Pb (2.5-3.25). The PLI (1.04-1.13) suggests that heavy metal contamination of sediments has occurred. Results showed that high concentrations of the toxic metals Pb and Cd were found in the sediment as well as in fish tissues. Length and weight of fish are significantly correlated (r2 = 0.98, p < 0.05). The study revealed that the mass fish kill was due to impulsive changes in the water quality and heavy metal pollution from untreated urban sewage discharges in this region.


Asunto(s)
Monitoreo del Ambiente , Estuarios , Peces , Metales Pesados , Contaminantes Químicos del Agua , Animales , Metales Pesados/análisis , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/toxicidad , India , Sedimentos Geológicos/química , Bahías
19.
Drug Dev Ind Pharm ; 39(5): 716-23, 2013 May.
Artículo en Inglés | MEDLINE | ID: mdl-22639963

RESUMEN

OBJECTIVE: The objective of present investigation was to evaluate performance of cocrystals of Mefloquine Hydrochloride (MFL) in tablet dosage form. Our previous investigation showed significant effect of cocrystal formers on improving the solubility and dissolution rate of Mefloquine hydrochloride by cocrystallization method when prepared by solution cocrystallization method. MATERIALS AND METHODS: Prepared cocrystals of MFL with different ratio of cocrystal formers were incorporated in tablet dosage form and evaluated for micrometric properties, drug content, hardness, disintegration test, vitro dissolution studies and stability studies. Performance was compared with laboratory prepared tablet of MFL 250 mg. RESULTS: The considerable improvement in the dissolution rate was observed in case of cocrystals based tablets than pure MFL tablets. DISCUSSION AND CONCLUSION: So we can incorporate cocrystals in tablet dosage form to enhance in vitro and in vivo performance. To the best of our knowledge, this is the first report, cocrystals has been evaluated in tablet dosage form.


Asunto(s)
Antimaláricos/química , Mefloquina/química , Disponibilidad Biológica , Química Farmacéutica , Cristalización , Estabilidad de Medicamentos , Modelos Moleculares , Solubilidad , Comprimidos
20.
Heliyon ; 9(4): e15416, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-37151638

RESUMEN

Melanoma is an abnormal proliferation of skin cells that arises and develops in most of the cases on surface of skin that is exposed to copious amounts of sunlight. This common type of cancer may develop in areas of the skin that are not exposed to a much abundant sunlight. The research addresses the problem of Segmentation and Classification of Melanoma Skin Cancer. Melanoma is the fifth most common skin cancer lesion. Bio-medical Imaging and Analysis has become more promising, interesting, and beneficial in recent years to address the eventual problems of Melanoma Skin Cancerous Tissues that may develop on Skin Surfaces. The evolved research finds that Attributes Selected for Classification with Color Layout Filter model. The research has produced an optimal result in terms of certain performance metrics accuracy, precision, recall, PRC (what is PRC? Expansion is needed in Abstract), The proposed method has yielded 90.96% of accuracy and 91% percent of precise and 0.91 of recall out of 1.0, 0.95 of ROC AUC, 0.87 of Kappa Statistic, 0.91 of F-Measure. It has been noticed a lowest error with reference to proposed method on certain dataset. Finally, this research recommends that the Attribute Selected Classifier by implementing one of the image enhancement techniques like Color Layout Filter is showing an efficient outcome.

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