Assessment of climatic and orographic conditions on the infection by Calicophoron daubneyi and Dicrocoelium dendriticum in grazing beef cattle (NW Spain)

From February 2003 to March 2004, 1148 faecal samples from autochthonous Rubia Gallega cattle breed were collected in 170 farms from Lugo (NW Spain), in order to find out the prevalence and intensity of egg-excretion by Calicophoron daubneyi and Dicrocoelium dendriticum, and the possible influence of external factors as annual mean temperature and rainfall, altitude and mean slope. Twenty-six percent (95% CI 19%, 33%) and the 18% (12, 24) of the farms were infected with rumen and lancet flukes. C. daubneyi egg-output (Me=24) was found in 13% (11, 15) of the individual samples. Six percent (5, 7) of the animals in the study had low D. dendriticum eggs (Me=8). By estimating the odds ratio values it was shown that the highest probability of infection by C. daubneyi was in pastures with a mean slope of less than 13% (OR=1.9) and situated under 600 m (OR=1.6). Annual mean rainfall and temperature were not identified as risk factors for the infection with rumen flukes. Mountainous pastures with a mean slope of higher than 25% (OR=5.8) and situated over 600 m (OR=24.6) where precipitation was high (>1000 mm; OR=7) and temperature low (<11 degrees C; 2.8) had involved the highest risk of infection by D. dendriticum. Because of the prevalences found in this study, employment of suitable management practices with strategic treatments with efficacious anthelmintics are needed to reduce the presence of both trematodes and to increase the health status of grazing beef cattle.     

Potassium permanganate elicits a shift of the external fish microbiome and increases host susceptibility to columnaris disease

The external microbiome of fish is thought to benefit the host by hindering the invasion of opportunistic pathogens and/or stimulating the immune system. Disruption of those microbial communities could increase susceptibility to diseases. Traditional aquaculture practices include the use of potent surface-acting disinfectants such as potassium permanganate (PP, KMnO₄) to treat external infections. This study evaluated the effect of PP on the external microbiome of channel catfish and investigated if dysbiosis leads to an increase in disease susceptibility. Columnaris disease, caused by Flavobacterium columnare, was used as disease model. Four treatments were compared in the study: (I) negative control (not treated with PP nor challenged with F. columnare), (II) treated but not challenged, (III) not treated but challenged, and (IV) treated and challenged. Ribosomal intergenic spacer analysis (RISA) and pyrosequencing were used to analyze changes in the external microbiome during the experiment. Exposure to PP significantly disturbed the external microbiomes and increased catfish mortality following the experimental challenge. Analysis of similarities of RISA profiles showed statistically significant changes in the skin and gill microbiomes based on treatment and sampling time. Characterization of the microbiomes using 16S rRNA gene pyrosequencing confirmed the disruption of the skin microbiome by PP at different phylogenetic levels. Loss of diversity occurred during the study, even in the control group, but was more noticeable in fish subjected to PP than in those challenged with F. columnare. Fish treated with PP and challenged with the pathogen exhibited the least diverse microbiome at the end of the study.     

The Seismic Structure of the Sun

Global Oscillation Network Group data reveal that the internal structure of the sun can be well represented by a calibrated standard model. However, immediately beneath the convection zone and at the edge of the energy-generating core, the sound-speed variation is somewhat smoother in the sun than it is in the model. This could be a consequence of chemical inhomogeneity that is too severe in the model, perhaps owing to inaccurate modeling of gravitational settling or to neglected macroscopic motion that may be present in the sun. Accurate knowledge of the sun's structure enables inferences to be made about the physics that controls the sun; for example, through the opacity, the equation of state, or wave motion. Those inferences can then be used elsewhere in astrophysics.     

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.     

Adsorption-desorption dynamics of cyprodinil and fludioxonil in vineyard soils

Cyprodinil and fludioxonil are new-generation fungicides that are employed to protect grapevines from botrytis and various rots. In this work, their adsorption and desorption dynamics in eight vineyard soils from Galicia (northwestern Spain) were examined in batch and column experiments. Both fungicides exhibited linear adsorption isotherms, with more ready adsorption (greater Kd) of fludioxonil. Kd values for cyprodinil were significantly correlated with soil organic matter content (r 2= 0.675, p < 0.01). Both pesticides exhibited adsorption-desorption hysteresis, but desorption was easier and more variable for cyprodinil (12-21%, RSD = 17%) than for fludioxonil (3-5%, RSD = 13%) and appeared to depend on the formation of irreversible bonds in the former case and on poor solubility in the latter. A linear adsorption model involving nonequilibrium conditions and an irreversible adsorption term was found to reproduce transport behavior accurately.     

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).     

Predominant Bacteria Associated with Red Snapper from the Northern Gulf of Mexico

Abstract

Since the Deepwater Horizon oil spill in 2010, anecdotal observations of Red Snapper Lutjanus campechanus from the northern Gulf of Mexico exhibiting unusual external lesions have been reported. Two opportunistic bacterial fish pathogens, Vibrio vulnificus and Photobacterium damselae, were recovered from the fish and were deemed responsible for the abnormalities. However, the culturable microbiota of healthy Red Snapper has not yet been characterized. We analyzed the heterotrophic bacteria associated with healthy Red Snapper caught off the Louisiana coast. In total, 179 isolates from 60 fish were recovered from skin and mucus, and 43 isolates were obtained from anterior kidney. All isolates were identified by 16S ribosomal RNA gene sequencing. The Proteobacteria was the predominant phylum in both external and internal samples, followed by the Firmicutes and the Actinobacteria. Within the Proteobacteria, most isolates were members of the genera Vibrio and Photobacterium, and V. natriegens and P. damselae were the predominant species. The results of this study suggest that both Vibrio spp. and Photobacterium spp. are associated with the normal microbiota of healthy Red Snapper. Thus, the opportunistic fish pathogens recovered in previous studies cannot be deemed lesion-forming until Koch's postulates are fulfilled.

Received March 1, 2013; accepted September 4, 2013     

Gateways or backdoors to development? Filtering mechanisms and territorial embeddedness in the Chilean copper GPN’s urban system

This paper analyses the role played by different urban nodes in the Chilean copper mining Global Production Network (GPN), and how filtering mechanisms act in favour of the capital city, limiting the territorial embeddedness of extractive industry in resource peripheries. In doing so, we make three contributions to the literature. First, in addition to observing gateway cities (those connecting the mining hinterlands to the global economy), we propose an intermediate category in urban hierarchies which we label the “backdoor city” (those that can perform one or more functions of a gateway city but lack chances for value capture and sustainable development outcomes). Second, we analyse the filtering mechanisms that work to the detriment of resources peripheries. Third, we analyse how these mechanisms reduce the territorial embeddedness of mining activity across the Chilean urban hierarchy. Our main results show that the capital city of Santiago stands out as the only gateway city in the country, and Antofagasta acts as a backdoor city for the Chilean resource peripheries where the extractive activity is weakly embedded, limiting their development opportunities.     

Optimizing Salting and Smoking of Catfish (Bagre marinus) Using Response Surface Methodology

ABSTRACT

Response surface methodology was used to assess the effects of brine concentration (0.1127–0.2473 g NaCl/g), salting time (49–271 min), smoking temperature (53.2–86.8°C), and smoking time (216–384 min) on moisture content, salt content, yield, taste preference, and texture preference of smoked catfish slices. Optimal process conditions were determined through the graphical method and desirability function approach. The desirability function showed that the optimal conditions for salting and smoking of catfish were: smoking temperature, 70°C; smoking time, 300 min; salting time, varying from 193.39 to 194.68 min; and brine concentration varying from 0.1791 to 0.1797 g NaCl/g. Under optimal conditions, moisture content, salt content, yield, taste preference, and texture preference of smoked catfish were 0.53 g water/g, 0.064 g NaCl/g, 58%, 3.7, and 3.7, respectively.