Zacatecas (Mexico) Companies Extract Hg from Surface Soil Contaminated by Ancient Mining Industries

In Zacatecas, Mexico, four plants are operating to extract Ag, Au, and Hg using CaS₂O₃ solution from surface soil containing tailings from the amalgamation method used during 1550–1900. The metal ions extracted are cemented by scrap Cu wires. Hg is separated by evaporation from the cemented amalgam and Ag and Au are obtained from the residue. A part of the soil to be leached was separated and leached as in the industrial process. Only 121 ppm of Hg was freed from 168 ppm of extractable Hg. About a half of the remaining Hg in the soil evaporated during 18 months. This confirms that the Hg in the soil is metallic. Pb and As are also freed in the same process. It is estimated that 13 000–34 000 t of Hg had been discarded in the extraction of Ag.     

Chronic Toxicity Study of Neosaxitoxin in Rats

Neosaxitoxin (NeoSTX) is a specific reversible blocker of voltage gated sodium channels on excitable cells. In the last decade, it has been tested in a number of interesting clinical trials, however there is still little information available on mammalian toxicity. Rats were treated for 12 weeks with doses of 1, 3 or 6 μg/kg of subcutaneous NeoSTX. At weeks 12 and 17, animals were sacrificed and blood samples collected for hematological and biochemical analysis. Organs were harvested for weight determination and histopathological assessments. The lowest acute toxicity via the intraperitoneal (ip) route was (30.35 μg/kg) and there was no significant difference between intramuscular and subcutaneous routes (11.4 and 12.41 μg/kg). The NeoSTX adiministration did not produce lethality at week 12 and after five weeks of suspension. NeoSTX 6 μg/kg ip produced reductions (p < 0.05) in body weight and food intake, and increased blood level of total and direct bilirubin, GGT and SGOT at week 12; all of these were reversed in the recovery period. NeoSTX 1 and 3 μg/kg ip did not show significant changes with the control group. Histopathological presentations were normal in all groups. This study revealed that NeoSTX is safe in vivo, giving a reliable security margin for its use like a local anesthetic.     

Marine Toxins Targeting Ion Channels

This introductory minireview points out the importance of ion channels for cell communication. The basic concepts on the structure and function of ion channels triggered by membrane voltage changes, the so-called voltage-gated ion channels (VGICs), as well as those activated by neurotransmitters, the so-called ligand-gated ion channel (LGICs), are introduced. Among the most important VGIC superfamiles, we can name the voltage-gated Na⁺ (Na_V), Ca²⁺ (Ca_V), and K⁺ (K_V) channels. Among the most important LGIC super families, we can include the Cys-loop or nicotinicoid, the glutamate-activated (GluR), and the ATP-activated (P2X_nR) receptor superfamilies. Ion channels are transmembrane proteins that allow the passage of different ions in a specific or unspecific manner. For instance, the activation of Na_V, Ca_V, or K_V channels opens a pore that is specific for Na⁺, Ca²⁺, or K⁺, respectively. On the other hand, the activation of certain LGICs such as nicotinic acetylcholine receptors, GluRs, and P2X_nRs allows the passage of cations (e.g., Na⁺, K⁺, and/or Ca²⁺), whereas the activation of other LGICs such as type A γ-butyric acid and glycine receptors allows the passage of anions (e.g., Cl⁻ and/or HCO₃⁻). In this regard, the activation of Na_V and Ca_V as well as ligand-gated cation channels produce membrane depolarization, which finally leads to stimulatory effects in the cell, whereas the activation of K_V as well as ligand-gated anion channels induce membrane hyperpolarization that finally leads to inhibitory effects in the cell. The importance of these ion channel superfamilies is emphasized by considering their physiological functions throughout the body as well as their pathophysiological implicance in several neuronal diseases. In this regard, natural molecules, and especially marine toxins, can be potentially used as modulators (e.g., inhibitors or prolongers) of ion channel functions to treat or to alleviate a specific ion channel-linked disease (e.g., channelopaties).     

The Nemertine Toxin Anabaseine and Its Derivative DMXBA (GTS-21): Chemical and Pharmacological Properties

Nemertines are a phylum of carnivorous marine worms that possess a variety of alkaloidal, peptidic or proteinaceous toxins that serve as chemical defenses against potential predators. The hoplonemertines additionally envenomate their prey with a mixture of proboscis alkaloids delivered with the help of a calcareous stylet that punctures the skin of the victim. Anabaseine, the first of these alkaloids to be identified, stimulates a wide variety of animal nicotinic acetylcholine receptors (AChRs), especially the neuromuscular [e.g., α1₂β1γδ (embryogenic) or α1₂β1γɛ (adult)] and α7 AChRs that are inhibited by the snake peptide α-bungarotoxin. A synthetic derivative, 3-(2,4-Dimethoxybenzylidene)-Anabaseine (DMXBA; also called GTS-21), improves memory in experimental animals and humans and is currently in clinical trials to determine whether it can ameliorate cognitive problems associated with schizophrenia. Here we summarize present knowledge concerning the chemistry and mechanisms of action of these two substances (anabaseine and DMXBA) on AChRs, especially those found in the mammalian brain.     

Soil quality effects on Chenopodium album flavonoid content and antioxidant potential

Antioxidant capacity, total phenolic content and flavonoid glycosides profile were compared in C.album samples grown in intensively cultivated (IC) and nondisturbed (ND) soils to evaluate differences in their nutraceutical potential. Petroleum ether, methanol, and aqueous extracts were sequentially obtained from C. album dried samples. Methanol crude extract exhibited the highest antioxidant potential and phenolic content, which were significantly enhanced by soil deterioration. This feature was enhanced in its ethyl acetate/n-buthanol subextract that also yielded higher amounts of the fraction containing flavonoid glycosides in samples grown in IC soils. Compounds were isolated by activity guided fractionation, and chemical structure-antioxidant activity relationships were established. Chemical structures were elucidated by chemical and spectroscopic methods. Six known flavonoid glycosides were isolated, and their antioxidant activity was determined by DPPH assay. 1, quercetin-3-O-(2",6"-di-O-R-L-rhamnopyranosyl)-beta-D-glucopyranoside; 2, kaempferol-3-O-(2",6"-di-O-R-L-rhamnopyranosyl)-beta-D-glucopyranoside; 3, quercetin-3-O-beta-D-glucopyranosyl-(1'-->6")-beta-D-glucopyranoside; 4, rutin; 5, quercetin-3-O-beta-D-glucopyranoside; and 6, kaempferol-3-O-beta-D-glucopyranoside. Triosides 1 and 2 were identified for the first time in C. album. Our results suggest that this edible weed, ubiquitously present in cultivated fields, should be considered as a nutraceutical food and an alternative source for nutrients and free radical scavenging compounds, particularly when collected from cultivated fields that seem to increase some of its advantages.     

Detection and quantification of transgenes in grains by multiplex and real-time PCR

Multiplex PCR reactions were developed for detecting simultaneously the CryIA(b) and pat genes from events 176, MON810, BT11, and T25 of transgenic maize, using only two pairs of primers, one for the CryIA(b) gene and the other for the pat gene. The Roundup Ready soybean can be precisely detected by a multiplex PCR reaction using known primers, amplifying fragments of the NOS and the epsps sequences simultaneously. Transgenic events such as Roundup Ready soybean and GA21 maize, among others, can be quantified by real-time PCR using a pair of primers and a probe specifically designed for annealing to the NOS ending region. As an alternative to amplifying an endogenous gene, the addition of a foreign gene in a percentage equal to the required level of detection, in a parallel reaction, is proposed. The use of hexane to homogenize large flour samples is suggested.     

Mixed culture optimization for marigold flower ensilage via experimental design and response surface methodology

Endogenous microorganisms isolated from the marigold flower (Tagetes erecta) were studied to understand the events taking place during its ensilage. Studies of the cellulase enzymatic activity and the ensilage process were undertaken. In both studies, the use of approximate second-order models and multiple lineal regression, within the context of an experimental mixture design using the response surface methodology as optimization strategy, determined that the microorganisms Flavobacterium IIb, Acinetobacter anitratus, and Rhizopus nigricans are the most significant in marigold flower ensilage and exhibit high cellulase activity. A mixed culture comprised of 9.8% Flavobacterium IIb, 41% A. anitratus, and 49.2% R. nigricans used during ensilage resulted in an increased yield of total xanthophylls extracted of 24.94 g/kg of dry weight compared with 12.92 for the uninoculated control ensilage.     

Diversity and symbiotic effectiveness of rhizobia isolated from field-grown soybean nodules in Paraguay

Soybean was introduced in Paraguay in the 1920s and commercial crops have been grown since the 1970s. Root nodulation occurs at the majority of the producing sites, although inoculation has been practiced in only 15-20% of the cropping areas. The diversity and symbiotic effectiveness of soybean rhizobia was studied using 78 isolates obtained from root nodules of field-grown plants at 16 sites located in the two main producing states. The rhizobial isolates were characterized in relation to several parameters in vitro (colony morphology, tolerance to high temperature and salinity, intrinsic resistance to antibiotics, synthesis of indole acetic acid, profiles of proteins and lipopolysaccharides) and in vivo (nodulation, plant growth and total N accumulated in shoots). Fifty-eight isolates had slow growth rates and alkaline reaction in medium containing mannitol as the carbon source, whereas 20 had fast growth rates and an acid reaction. Most isolates did not tolerate acidity (pH 4.5) or high temperature (40°C). Very few isolates shared similar protein and lipopolysaccharide profiles; therefore a high level of diversity was detected, with most of the isolates representing unique strains. Some of the isolates with an outstanding symbiotic performance were identified, and will now be tested under field conditions in a search for efficient and competitive strains for use in commercial inoculants in Paraguay.     

Towards a systemic research methodology in agriculture: Rethinking the role of values in science

The recent drastic developmentof agriculture, together with the growingsocietal interest in agricultural practices andtheir consequences, pose a challenge toagricultural science. There is a need forrethinking the general methodology ofagricultural research. This paper takes somesteps towards developing a systemic researchmethodology that can meet this challenge – ageneral self-reflexive methodology that forms abasis for doing holistic or (with a betterterm) wholeness-oriented research and providesappropriate criteria of scientific quality.From a philosophy of research perspective,science is seen as an interactive learningprocess with both a cognitive and a socialcommunicative aspect. This means, first of all,that science plays a role in the world that itstudies. A science that influences its ownsubject area, such as agricultural science, isnamed a systemic science. From thisperspective, there is a need to reconsider therole of values in science. Science is notobjective in the sense of being value-free.Values play, and ought to play, an importantrole in science – not only in form ofconstitutive values such as the norms of goodscience, but also in the form of contextualvalues that enter into the very process ofscience. This goes against the traditionalcriterion of objectivity. Therefore, reflexive objectivity is suggested as a newcriterion for doing good science, along withthe criterion of relevance. Reflexiveobjectivity implies that the communication ofscience must include the cognitivecontext, which comprises the societal,intentional, and observational context. Inaccordance with this, the learning process ofsystemic research is shown as a self-reflexivecycle that incorporates both an involved actorstance and a detached observer stance. Theobserver stance forms the basis for scientificcommunication.To this point, a unitary view of science asa learning process is employed. A secondimportant perspective for a systemic researchmethodology is the relation between the actual,different, and often quite separate kinds ofscience. Cross-disciplinary research ishampered by the idea that reductive science ismore objective, and hence more scientific, thanthe less reductive sciences of complex subjectareas – and by the opposite idea thatreductive science is necessarilyreductionistic. Taking reflexive objectivity asa demarcator of good science, an inclusiveframework of science can be established. Theframework does not take the establisheddivision between natural, social, and humanscience as a primary distinction of science.The major distinction is made between theempirical and normative aspects of science,corresponding to two key cognitive interests.Two general methodological dimensions, thedegree of reduction of the research world andthe degree of involvement in the researchworld, are shown to span this framework. Theframework can form a basis fortransdisciplinary work by way of showing therelation between more and less reductive kindsof science and between more detached and moreinvolved kinds of science and exposing theabilities and limitations attendant on thesemethodological differences.