Factors that influence the migration of sorbed pesticides in polyethylene and biodegradable mesoplastics.

Trifluralin, Chlorpyrifos, and Procymidone migration performance from polyethylene (PE) and biodegradable (Mater-Bi: M-B) mulching films was examined. Desorption of pesticides from PE and M-B was studied using soil-plastic microcosms, considering temperature, soil humidity, and mulching film type as experimental variables. Trifluralin and Chlorpyrifos desorption was higher for PE than for M-B under all experimental conditions.

Macro, meso, micro and nanoplastics in horticultural soils in Argentina: Abundance, size distribution and fragmentation mechanism.

Soil contamination with plastics is a major worldwide concern. However, data on plastic pollution in horticultural soils from Latin America is scarce. Furthermore, there is limited information on the fragmentation process that plastics undergo in environmental conditions.

Thermal paper as a potential source of bisphenol A for humans and the environment: migration and ecotoxicological impact.

The objective of this work was to evaluate thermal paper (TP) tickets used in Argentina as a potential source of bisphenol A (BPA) that could impact humans and the environment. BPA in TP was measured by HPLC ranging from 11.1 to 30.

Environmental fate of dibutylphthalate in agricultural plastics: Photodegradation, migration and ecotoxicological impact on soil.

Phthalic acid esters (PAEs) were determined in polyethylene covers used in horticultural production units located at Moreno and La Plata districts (Buenos Aires, Argentina), detecting 0.69-8.75 mg PAEs kg plastic in greenhouse and tunnel films.

One Step Histological Detection and Staining of the PTEN Tumor Suppressor Protein by a Single Strand DNA.

Antibodies are the most used technological tool in histochemistry. However, even with monoclonal antibodies, their standardization is difficult due to variation of biological systems as well as to variability due to the affinity and amplification of the signal arising from secondary peroxidase detection systems. In this article we combined two synthetic molecules to facilitate the standardization of a detection protocol of protein markers in histological sections.

Core modified 8-17 DNAzymes with 2'-deoxy-2'-C-methylpyrimidine nucleosides.

The catalytic core of an 8-17 DNAzyme directed against STAT 3 was modified using (2'R) and (2'S) 2'-deoxy-2'-C-methyluridine and cytidine. While 2'-deoxy-2'-C-methyluridine significantly diminished the catalytic activity, 2'-deoxy-2'-C-methylcytidine replacement was better accepted, being the k of modified DNAzymes at 8- and 11-positions comparable to the non-modified one. When 2'-O-methyl and phosphorothioate nucleotides were tested in the binding arms together with core modified DNAzymes the k was affected in a non predictable way, emphasizing the fact that both chemical substitutions should be considered globally.

Human exposure and mass balance distribution during procymidone application in horticultural greenhouses.

The purpose of this study was to analyze the impact of procymidone application in periurban horticultural greenhouses, especially on workers (applicators and assistants) and soil and plastic mulching, when mechanically pressurized application systems were employed. The mean Potential Dermal Exposure (PDE) was measured using the Whole Body Dosimetry technique. The PDE for the applicators was 188 mL h ± 103 mL h, and 14.

Fatty acid extraction from sewage sludge using a porous polyethylene sorbent obtained from agricultural covers.

Fatty acids from a sewage sludge of a wastewater treatment plant were extracted using a porous polyethylene (pPE) material prepared using agricultural plastic films. The pPE fatty acid extraction profile and yield from the sewage sludge was compared to toluene as extraction solvent. The chemical composition of the extracted fatty acids were the same in both cases, but when the extraction yield was normalized by the used mass of pPE or toluene, pPE resulted six times more efficient than toluene.

siRNA Modified with 2'-Deoxy-2'-C-methylpyrimidine Nucleosides.

(2'S)-2'-Deoxy-2'-C-methyluridine and (2'R)-2'-deoxy-2'-C-methyluridine were incorporated in the 3'-overhang region of the sense and antisense strands and in positions 2 and 5 of the seed region of siRNA duplexes directed against Renilla luciferase, whereas (2'S)-2'-deoxy-2'-C-methylcytidine was incorporated in the 6-position of the seed region of the same constructions. A dual luciferase reporter assay in transfected HeLa cells was used as a model system to measure the IC values of 24 different modified duplexes. The best results were obtained by the substitution of one thymidine unit in the antisense 3'-overhang region by (2'S)- or (2'R)-2'-deoxy-2'-C-methyluridine, reducing IC to half of the value observed for the natural control.

Characterization and electrochemical response of DNA functionalized 2nm gold nanoparticles confined in a nanochannel array.

Polyvalent gold nanoparticle oligonucleotide conjugates are subject of intense research. Even though 2nm diameter AuNPs have been previously modified with DNA, little is known about their structure and electrochemical behavior. In this work, we examine the influence of different surface modification strategies on the interplay between the meso-organization and the molecular recognition properties of a 27-mer DNA strand.

Stabilization of Telomeric I-Motif Structures by (2'S)-2'-Deoxy-2'-C-Methylcytidine Residues.

G-quadruplexes and i-motifs are tetraplex structures present in telomeres and the promoter regions of oncogenes. The possibility of producing nanodevices with pH-sensitive functions has triggered interest in modified oligonucleotides with improved structural properties. We synthesized C-rich oligonucleotides carrying conformationally restricted (2'S)-2'-deoxy-2'-C-methyl-cytidine units.

Human and soil exposure during mechanical chlorpyrifos, myclobutanil and copper oxychloride application in a peach orchard in Argentina.

The objective of this study was to measure the impact of the mechanized chlorpyrifos, copper oxychloride and myclobutanil application in a small peach orchard, on humans (operators, bystanders and residents) and on the productive soil. The mean Potential Dermal Exposure (PDE) of the workers (tractor drivers) was 30.8mL·h±16.

Modified Nucleoside Triphosphates for In-vitro Selection Techniques.

The development of SELEX (Selective Enhancement of Ligands by Exponential Enrichment) provides a powerful tool for the search of functional oligonucleotides with the ability to bind ligands with high affinity and selectivity (aptamers) and for the discovery of nucleic acid sequences with diverse enzymatic activities (ribozymes and DNAzymes). This technique has been extensively applied to the selection of natural DNA or RNA molecules but, in order to improve chemical and structural diversity as well as for particular applications where further chemical or biological stability is necessary, the extension of this strategy to modified oligonucleotides is desirable. Taking into account these needs, this review intends to collect the research carried out during the past years, focusing mainly on the use of modified nucleotides in SELEX and the development of mutant enzymes for broadening nucleoside triphosphates acceptance.

Exploring the Use of a Guanine-Rich Catalytic DNA for Sulfoxide Preparation.

A guanine-rich DNA oligonucleotide complexed with hemin was used to catalyze controlled oxygen transfer reactions to different sulfides for sulfoxide preparation in the presence of H2O2. Comparable activities were obtained when using fully modified L-DNA. In addition, oligonucleotide immobilization led to an active catalyst which could be successfully recovered and reused without loss of activity.

Polyethylene film incorporation into the horticultural soil of small periurban production units in Argentina.

Horticulture makes intensive use of soil and extensive use of polyethylene (PE) sheeting and pesticides, producing an environment where the dynamics between soil and plastics can affect pesticide fate. We have determined that the presence of plastic residues in the horticultural soil of small production units equals 10% of the soil area, being meso and macro-sections the predominant fragment sizes. All soil samples were taken from different plots located in Cuartel V, Moreno district, in the suburbs of Buenos Aires city, Argentina.

Confined gold nanoparticles enhance the detection of small molecules in label-free impedance aptasensors.

A controlled architecture of nanoelectrodes, of a similar size to small molecule-binding aptamers, is synthesized inside nanoporous alumina. Gold nanoparticles with a controlled size (about 2 nm) are electrogenerated in the alumina cavities, showing a fast electron transfer process toward ferrocyanide. These uncapped nanoparticles are easily modified with a thiol-containing aptamer for label-free detection of adenosine monophosphate by electrochemical impedance spectroscopy.

Activity of core-modified 10-23 DNAzymes against HCV.

The highly conserved untranslated regions of the hepatitis C virus (HCV) play a fundamental role in viral translation and replication and are therefore attractive targets for drug development. A set of modified DNAzymes carrying (2'R)-, (2'S)-2'-deoxy-2'-C-methyl- and -2'-O-methylnucleosides at various positions of the catalytic core were assayed against the 5'-internal ribosome entry site element (5'-IRES) region of HCV. Intracellular stability studies showed that the highest stabilization effects were obtained when the DNAzymes' cores were jointly modified with 2'-C-methyl- and 2'-O-methylnucleosides, yielding an increase by up to fivefold in the total DNAzyme accumulation within the cell milieu within 48 h of transfection.

Pesticide potential dermal exposure during the manipulation of concentrated mixtures at small horticultural and floricultural production units in Argentina: the formulation effect.

Potential dermal exposure measurements of horticultural and floricultural field operators that handled concentrated pesticides showed a correlation with the types of formulations used (liquid or solid) during the mix and load stage. For liquid formulations, hand exposure was 22-62 times greater than that for solid ones. The dermal exposure mechanism was studied for this formulation under laboratory conditions, finding that the rupture of the aluminum seal of the pesticide container and the color of the liquid formulation are important factors.

Conformational states of 2'-C-methylpyrimidine nucleosides in single and double nucleic acid stranded structures.

The hybridization performance of a set of 12-mer RNA:RNA duplexes containing 2'-C-methyluridine, 5-bromo-2'-C-methyluridine, or (2'S)-2'-deoxy-2'-C-methyluridine was analyzed. Melting point temperatures of the modified duplexes showed an important ΔT(m) decrease (-8.9 to -12.

Influence of conformationally restricted pyrimidines on the activity of 10-23 DNAzymes.

The catalytic core of a 10-23 DNAzyme was modified introducing conformationally restricted nucleosides such as (2'R)-, (2'S)-2'-deoxy-2'-C-methyluridine, (2'R)-, (2'S)-2'-deoxy-2'-C-methylcytidine, 2,2'-anhydrouridine and LNA-C, in one, two or three positions. Catalytic activities under pseudo first order conditions were compared at different Mg(2+) concentrations using a short RNA substrate. At low Mg(2+) concentrations, triple modified DNAzymes with similar kinetic performance to that displayed by the non-modified control were identified.

Cationic amino acid uptake constitutes a metabolic regulation mechanism and occurs in the flagellar pocket of Trypanosoma cruzi.

Trypanosomatids' amino acid permeases are key proteins in parasite metabolism since they participate in the adaptation of parasites to different environments. Here, we report that TcAAP3, a member of a Trypanosoma cruzi multigene family of permeases, is a bona fide arginine transporter. Most higher eukaryotic cells incorporate cationic amino acids through a single transporter.

Environmental pesticide distribution in horticultural and floricultural periurban production units.

The environmental pesticide distribution on non-target systems (soil, drift and agricultural plastics) during the application step at small periurban production units, was studied in open field and greenhouses, for different crops (tomato, lettuce, broccoli, strawberry and flowers) using different pesticides (endosulfan, procymidone, chlorothalonil, chlorpyrifos and deltamethrin). In all cases, soil was the most exposed non-target system. For greenhouses, a general pesticide distribution was found of approximately 2/3 for crop, 1/4 for soil and 1/20 for plastic, of the total amount applied.

Pesticide risk assessment in flower greenhouses in Argentina: the importance of manipulating concentrated products.

An evaluation of the Potential Dermal Exposure of workers to endosulfan and procymidone at the mix/load and application stages was done in small floricultural production units in Argentina. Seven experiments were performed with different operators under typical greenhouse conditions, based on the whole body dosimetry methodology. These results indicate that the mean Potential Dermal Exposure of the application step was 45.

10-23 DNAzyme modified with (2'R)- and (2'S)-2'-deoxy-2'-C-methyluridine in the catalytic core.

The catalytic core of a 10-23 DNAzyme was modified using (2'R), (2'S)-2'-deoxy-2'-C-methyluridine and LNA-T. Catalytic activities under pseudo first order conditions were compared at different Mg(2+) concentrations, indicating that certain 2'-C-methyl modified DNAzymes have significant activities. Resistance against MCF-7 cell lysate and endonuclease RQ1 was also measured, showing that the introduction of 2'-C-methyl-2'-deoxynucleosides increased the stability.

Potential dermal exposure in greenhouses for manual sprayers: analysis of the mix/load, application and re-entry stages.

An evaluation of the Potential Dermal Exposure for the mix/load, application and re-entry stages, associated with procymidone and deltamethrin usage, was carried out for tomatoes grown in greenhouses of small production units in Argentina. Eight experiments were done with four different operators, under typical field conditions with a lever operated backpack sprayer. The methodology applied was based on the Whole Body Dosimetry technique, evaluating a set of different data for the mix and load, application and re-entry operations.