TIP Revista Especializada en Ciencias QuimicoBiologicas最新文献

A methodology by SPME-GC-MS was developed and optimized for the simultaneous determination of pharmaceutical and personal care products (PPCP's) in wastewater: ibuprofen, naproxen, chlorofen, triclosan and bisphenol A. The extraction of analytes was performed by SPME using a fiber of PEG (Polietylenglycol), stirring of 1,200 rpm, 30 min extraction time at ambient temperature, 50% NaCl, pH=3 and derivatization on fiber with MTBSTFA (N-methyl-N-tert-butyl-dimethylsilil-trifluoroacetamide). The identification of the analytes was done by comparison of the retention times and the mass spectrum of standards. The quantification was done by selective ion monitoring (SIM) mode. The developed method shown acceptable linearity in the range of 1.0-118.90 pg/mL for ibuprofen, 48.0-1488 pg/mL for naproxen, 4.40-140.8 pg/mL for triclosan, 1.0-58.32 pg/mL for chlorofen, and 1.0-59.16 pg/mL for bisphenol A, all of them with correlation coefficients > 0.99. Several water samples from influents and effluents were analyzed from three wastewater treatment plants in the south of the Mexico City: “University”, “Coyoacan” and “Cerro de la Estrella” all of them belong to the water system of Mexico City. It was shown in this work that SPME is a sample preparation technique that is simple, reproducible, sensitive and fast because it reduces the steps by extracting and simultaneously concentrating the analytes without the use of organic solvents.

Predation as an evolutionary mechanism of diversification is a topic of great interest. Durophagy is the feeding behavior of preying on hard-shelled or exoskeleton-bearing organisms. On this matter, because of their worldwide distribution, abundance, wide range of habitats, and a remarkable preservation frequency, mollusks are of particular interest in the study of predation in the fossil record. In the present work, papers published in international scientific magazines focusing on the issue of durophagy on fossil marine bivalve and gastropods as potential prey were analyzed. A total of 101 papers on this subject were reviewed. Six-kinds of evidence of durophagy were identified: drilling, repaired and fragmented shells, bites, punctures and coprolites. Most items are of Cenozoic age and the majority of the records available correspond to the tropics. Most Paleozoic potential predators were not identified; this situation extends to the Mesozoic, but predation of gastropods and bivalves by carnivorous gastropods, arthropods, fishes and reptiles was recognized. Predation by naticid and muricid gastropods prevails during the Cenozoic, also was recognized predation by arthropods, fishes and mammals.

In this work we report the oxidation of volatile organosulfur compounds (VOC) catalyzed by the enzyme chloroperoxidase from Caldariomyces fumago. VOC are regarded as atmospheric pollutants due to their unpleasant odor and low detection threshold. Diethyl sulfide, dimethyl disulfide, propanethiol, butanethiol and hexanethiol were found to be substrates for the enzyme in a liquid medium reaction at pH 6, under peroxidatic conditions. Product analysis showed that sulfides were oxidized to their respective sulfoxides whereas thiols were oxidized to the corresponding disulfides. The identified products showed significantly lower vapor pressure than the parental compounds; thus, the products are not considered atmospheric pollutants. A 70-mL two-phase reactor was assembled in order to determine the efficiency of the enzymatic treatment. The liquid phase, consisting of 15% organic solvent and 85% buffer, was contacted with the gaseous phase, consisting of a substrate-enriched air stream. Using dimethyl disulfide as model substrate, we found that only enzymatic oxidation occurred in this system; by controlling the enzyme and peroxide concentration, we found that the substrate is transferred to the aqueous phase where 1 mol of enzyme converted approximately 12,400 mol of substrate, thus highlighting the potential of enzymatic treatment of malodorous gaseous streams.

A group of storage proteins highly abundant in cereal seeds are the prolamins, characterized by the frequent presence of proline in their sequence. The barley prolamins are known as hordeins. The aim of this study was to obtain the hordein banding patterns for five different Mexican barley cultivars in mature seeds. In addition, the hordein patterns in processed malt of four mexican and a canadian (Metcalfe) barley cultivars were obtained. Mass Spectrometry (MS), using distinct digestion protocols, identified differential bands in the patterns. Major differences in the seed patterns between cultivars consisted in discrete bands at 100 kDa, 65 kDa and in the range of 37 to 45 kDa. In malt, the patterns were highly contrasting among Mexican cultivars as well as in Metcalfe, suggesting that hordein processing during germination and malt processing is particular to each cultivar. Finally, the MS identification demonstrated that trypsin digestion is appropriate to distinguish B and γ hordeins in malt, whereas sequential digestion with chymotrypsin and trypsin allows the identification of C hordeins in seed.

The origin of life is rooted in the most primitive events of planetary evolution, events which were faithfully registered by the extraterrestrial bodies today called meteorites, and which formed the main constituent of rocky planets, such as Mercury, Venus, Earth and Mars. This register includes the chemical compounds precursors of life, as well as those high-energy events, whose nature could have accelerated the process of chemical evolution leading to life or delaying it.

On the other hand, Geology is the science that studies those objects and processes which have marked the planetary evolution of the interior of the Solar System, and consequently it is closely interrelated with the science of Meteoritics. This work analyses this intrinsic relationship by firstly considering the chemical and mineralogical properties of the actual meteorite populations because they represent the remaining of the objects (planetesimals), the coalescence of which formed the planets at the beginnings of the Solar Systems, and then deals with the negative or positive consequences of that accretionary process for the generation of life on Earth. As the main conclusion of this work thus, it may be stated that Geology and Meteoritics comprise the study natural processes intimately related with the early history of the Earth leading to the appearance of life only 1,000 million years (Ma) after the formation of the planet.

More than a decade of Mexican researcher's work resulted in the commercialization of Fungifree AB®. The development of the project involved aspects ranging from basic science research to product registration before Mexican authorities. This development required that the scientist involved had a technological rather than academic approach, allowing the protection of the innovation by a patent and the creation of a spin-off company, which eventually put the biofungicide into the market.

Fungifree AB® is the first biofungicide in the market fully developed in Mexico. It has been recognized by national and international organizations with innovation awards. Futhermore, organic certification was obtained on November 2014. The project involved collaborative work of several public and private institutions, bringing to the market an effective product for the safe production of high quality fruits and vegetables leaving no pesticides residues. This last property, allows the farmers the possibility to export their products to international markets in which the use of chemical pesticides is highly regulated.

Phytoplankton Channel El Bordo in Xochimilco was studied during the 2008 rainy season and the dry season of 2009. The objective was to determine the stability of the flora of an area requiring remediation. The results of this study showed a diverse composition of phytoplankton, which highlighted the registration of several species not previously observed in Mexico and specifically in Xochimilco. Monitoring results reflect the physicochemical factors ratio low variation (9-17%), although the intensity of agricultural activities prevalent in the study area. A third result was the identification of a functional group that brings together species that are typical of shallow water bodies, tropical and eutrophic, such as channel El Bordo. The possibility to associate this functional group with a stable state in the ecosystem, which can be applied in remediation is discussed. We find it useful to study communities of urban aquatic ecosystems with a high degree of alteration, since the amount of accumulated knowledge in a region could make the difference between keeping or losing these ecosystems.

In this work, the organization of the antennal lobes (ALs) and its topographic representation in the mushroom bodies (MBs) in soldiers of two species of ants has been compared. Morphologic comparison between these species suggests that ALs of A. mexicana could be more specialized than that of C. ocreatus at the expense of general capabilities. In both species the AL is organized in six groups of glomeruli, each of which innervated by its own tract. Glomeruli clusters are grouped in two regions, anterior and posterior, by the innervation of projection neurons (PNs) that connect AL with MBs via antennoprotocerebral tracts (APT). Calyces of MBs are layered and receive segregated olfactory information: PNs innervating anterior glomeruli clusters send axons through lateral-APT to the lateral horn (LH) and then to inner layer of the calyx, while PNs innervating posterior glomeruli clusters send axons through medial-APT to inner layers of the calyx and then to the LH. These results show that AL organization is topographically represented in the MB forming a coarse odotopic map. The two pathways connecting AL with MB could represent two channels for processing different kinds of odors or different properties of olfactory stimuli. The neuroanatomical results suggest a conserved functional organization in social hymenopterans.

To survive, organisms must adapt to sudden environmental changes that exert a selective pressure and therefore, their chances of survival depend on their ability to respond quickly and accurately. Adapting to these changes is closely linked to the correct perception and transmission of stimuli and the generation of appropriate responses. Two component systems (TCS) allow different bacteria, fungi, slime molds and plants to regulate their physiology according to the environmental conditions. In these molecular circuits, the mechanism of communication between modules is the consecutive phosphorylation of His and Asp residues located in sensor histidine kinase and response regulator protein pairs. This review highlights the most relevant features of TCS and their role in the perception and response to diverse stimuli. Finally, the differences between prokaryotic and eukaryotic TCS are illustrated using the osmotic response in Escherichia coli and Saccharomyces cerevisiae.

Linton found out that the dipole moment of pyridine N-oxide is appreciably smaller than the expected theoretical value. Thus, he postulated the contribution of three ‘excited structures’, with a negative electric charge at the 2-, 4- and 6-position. However, a typical electrophilic substitution such as nitration, afforded only the 4-nitro derivative. This discrepancy between theory and experiment prompted us to study the pyridine N-oxide physical properties, since its reactivity is derived from them. Besides, these negative charged rings require an unexpected polarization and a reaction mechanism must be provided. We propose intermolecular induced polarization as a viable path. We uncovered that only one of the three structures before mentioned is supported by the observed reactivity and by ¹³C nuclear magnetic resonance data. On rejecting 2 of the Linton’ s ‘excited structures’, we have explained the regioselectivity found in pyridine N-oxide nitration