Parasites of the pleasure oyster Crassostrea corteziensis cultured in Nayarit, Mexico

The pleasure oyster Crassostrea corteziensis is collected and cultured in Nayarit on the Pacific coast of Mexico, and the improvement and promotion of its culture are seen as a possible source for the economic development of coastal populations. However, information about the parasite fauna of the pleasure oyster is almost completely lacking. A histopathological survey carried out in two estuaries, Boca del Camichín and Pozo Chino, revealed the presence of hypertrophied gametes, rickettsiales-like prokaryotes (RLPs), the protozoan Perkinsus marinus, a protozoan Nematopsis sp., Ancistrocoma-like ciliates (ALCs), Sphenophrya-like ciliates, a turbellarian Urastoma sp., and encysted crustaceans. In general, prevalence and intensity of parasites were similar in both localities except that ALCs and encysted crustaceans were more prevalent in Pozo Chino than in Boca del Camichín. Perkinsus marinus and RLPs seem to represent a more significant risk for the health of pleasure oysters than do the other parasites, and surveillance and control of these parasites are needed for the development of pleasure oyster culture.     

Readaptation to the wild of rehabilitated loggerhead sea turtles (Caretta caretta) assessed by satellite telemetry

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Dry and Rainy Seasons Significantly Alter the Gut Microbiome Composition and Reveal a Key Enterococcus sp. (Lactobacillales: Enterococcaceae) Core Component in Spodoptera frugiperda (Lepidoptera: Noctuidae) Corn Strain From Northwestern Colombia

Spodoptera frugiperda is a polyphagous pest of several crops of economic importance. Nowadays, the insect is broadly distributed in America and, recently, in Africa, Asia, and Australia. The species has diverged into corn and rice strains. The role of the gut microbiota in insect physiology is relevant due to its participation in crucial functions. However, knowledge of seasonal variations that alter the gut microbiome in pests is limited. Gut microbiome composition between the dry and rainy seasons was analyzed with cultured and uncultured approaches in S. frugiperda corn strain larvae collected at Northwest Colombia, as seasonal microbiome changes might fluctuate due to environmental changes. On the basis of culture-dependent methods, results show well-defined microbiota with bacterial isolates belonging to Enterococcus, Klebsiella (Enterobacteriales: Enterobacteriaceae), Enterobacter (Enterobacterales: Enterobacteriaceae), and Bacillus (Bacillales: Bacillaceae) genera. The community composition displayed a low bacterial diversity across all samples. The core community detected with uncultured methods was composed of Enterococcus, Erysipelatoclostridium (Erysipelotrichales: Erysipelotrichaceae), Rasltonia (Burkholderiales: Burkholderiaceae), and Rhizobium (Hyphomicrobiales: Rhizobiaceae) genera, and Enterobacteriaceae family members. Significant differences in microbiome diversity were observed between the two seasons. The relative abundance of Erysipelatoclostridium was high in the dry season, while in the phylotype ZOR0006 (Erysipelotrichales: Erysipelotrichaceae) and Tyzzerella (Lachnospirales: Lachnospiraceae) genus, the relative abundance was high in the rainy season. The overall low gut bacterial diversity observed in the S. frugiperda corn strain suggests a strong presence of antagonist activity as a selection factor possibly arising from the host, the dominant bacterial types, or the material ingested. Targeting the stability and predominance of this core microbiome could be an additional alternative to pest control strategies, particularly in this moth.     

Anatomical and radiological study of the thoracic paravertebral space in dogs: iohexol distribution pattern and use of the nerve stimulator

ObjectiveTo describe the landmarks and methodology to approach the thoracic paravertebral space in dogs; to evaluate if intercostal muscular response could be evoked by a nerve-stimulator; to radiographically assess the distribution pattern of a radio-opaque contrast medium after thoracic paravertebral injections.Study designRandomized, controlled, experimental trial.AnimalsTwo mongrel dog cadavers (anatomical study) and 24 mongrel dogs (experimental study).MethodsFor the anatomic study 0.2 mL kg^?1 of new methylene blue (NMB) was injected at the 5th thoracic paravertebral space; for the experimental study dogs were divided into three groups and received 1 (T₅), 2 (T₄ and T₆) or 4 (T₄, T₅, T₆ and T₇) paravertebral injections of iohexol. The paravertebral approach was performed with insulated needles using landmarks and a blind technique. When the needle tip reached the respective thoracic paravertebral space, the nerve-stimulator was switched-on and the presence/absence of intercostal muscular twitch was registered, thus a total volume of 0.2 mL kg^?1 of iohexol, divided into equal parts for each injection point, was administered. Radiological studies were performed with two orthogonal projections at different times. Positive injection was confirmed when the paravertebral space was occupied by iohexol in both projections.ResultsNMB was distributed in the T₅ paraverterbal space. In the experimental study, when the needle tip reached the respective paravertebral space, intercostal twitching was obtained in 80% of the total injections with a stimulating current of 0.5 mA. The incidence of positive cases when the intercostal twitch was obtained with 0.5 mA was 83.3%. The main distribution pattern observed was cloud like without longitudinal diffusion.Conclusion and clinical relevanceIntercostal muscular responses obtained with a stimulating current of 0.5 mA could be useful to locate thoracic spinal nerves in dogs and in our study the injected solution was confined to one thoracic paravertebral space.     

Antagonism of pheromone response of Ostrinia nubilalis males and implications on behavior in the laboratory and in the field

The antagonistic effect on the pheromone response and catabolism of male European corn borers, Ostrinia nubilalis, by several trifluoromethyl ketones is reported. (Z)-11-Tetradecenyl trifluoromethyl ketone (Z11-14:TFMK), the most closely related analogue of the main component of the pheromone, elicits a remarkable disruptive effect on close approach and source contact of males flying to a source baited with mixtures of the pheromone and the antagonist in 5:1 and 10:1 ratios. In this experiment, the male displayed an erratic flight track with frequent counter turns and intersections with the plume. In the field, the TFMK significantly lowered the number of males caught when mixed with the pheromone in a 10:1 ratio in comparison with the natural attractant. The compound was also a good inhibitor of the antennal esterase of the insect with a IC(50) value of 0.28 muM. The homologous (Z)-10-tridecenyl trifluoromethyl ketone, with one carbon less in the chain, also elicited an antagonistic effect in the wind tunnel, but in the field, the results were not conclusive. The effect induced was lower than the one displayed by Z11-14:TFMK including the activity as the esterase inhibitor (IC(50) value of 7.55 muM). The saturated tetradecyl trifluoromethyl ketone, tetradecyltrifluoropyruvamide, and (Z)-11-2-thiatetradecenyl trifluoromethyl ketone resulted completely inactive. The results obtained in conjunction to the previously shown low toxicity to mice by related trifluoromethyl ketones provide new important data for the putative utilization of these chemicals as new pest control agents.     

Effects of Collembola on plant-pathogenic fungus interactions in simple experimental systems

 Take-all and brown foot rot, caused respectively by Gaeumannomyces graminis var. tritici and Fusarium culmorum, are two important components of the foot and root fungal disease complex of winter cereals world-wide. These fungi persist in soil and in crop debris in the same layer of agricultural soil as Collembola, a well represented taxon of soil animals. Previous in vitro tests showed that these fungi grown on agarised medium were readily consumed by springtails. In a simplified experimental system with wheat plants and the pathogenic fungi grown on millet and wheat kernels, the severity of disease was significantly reduced by collembolan feeding activity. Received: 18 April 2000     

Evaluation of the cytotoxicity, genotoxicity, mutagenicity, and antimutagenicity of propolis from Tucuman, Argentina

This study evaluates the toxic, genotoxic/mutagenic, and antimutagenic effects of propolis extract from Amaicha del Valle, Tucumán, Argentina. The cytotoxicity assays carried out with the lethality test of Artemia salina revealed that the LD50 was around 100 microg/mL. Propolis extracts showed no toxicity to Salmonella typhimurium TA98 and TA100 strains and Allium cepa at concentrations that have antibiotic and antioxidant activities. Otherwise, for the testing doses, neither genotoxicity nor mutagenicity was found in any sample. The propolis extracts were able to inhibit the mutagenesis of isoquinoline (IQ) and 4-nitro o-phenylenediamine (NPD) with ID50 values of 40 and 20 microg/plate, respectively. From this result, the studied propolis may be inferred to contain some chemical compounds capable of inhibiting the mutagenicity of direct-acting and indirect-acting mutagens. A compound isolated from Amaicha del Valle propolis, 2',4'-dihydroxychalcone, showed cytotoxic activity (LC50 values of 0.5 microg/mL) but was not genotoxic or mutagenic. Furthermore, this compound was able to inhibit the mutagenicity of IQ (ID50 values of 1 microg/plate) but was unable to inhibit the mutagenicity of NPD. Our results suggest a potential anticarcinogenic activity of Amaicha del Valle propolis and the chalcone isolated from it.     

Determination of the absolute molecular weight averages and molecular weight distributions of alginates used as ice cream stabilizers by using multiangle laser light scattering measurements

High-performance size exclusion chromatography with multiangle laser light scattering detection (HPSEC-MALLS) was used for characterizing complete molecular weight distributions for a range of commercial alginates used as ice cream stabilizers. For the samples investigated, molecular weight averages were found to vary between 115 000 and 321 700 g/mol and polydispersity indexes varied from 1. 53 to 3.25. These samples displayed a high content of low molecular weights. Thus, the weight percentage of material below 100 000 g/mol ranged between 6.9 and 54.4%.     

Characterization of bacterial diversity at different depths in the Moravia Hill landfill site at Medellín, Colombia

A combination of culture-dependent and culture-independent methods was used to assess bacterial diversity at different depths within a former solid waste dump in Medellín, Colombia. Sampling sites included a densely populated area, which is built upon 40 m of solid waste (domestic, industrial, agricultural, and medical). The soil and leachate contain high levels of contaminants and the natural soil is highly disturbed with solid anthropogenic materials, disrupting natural aggregation and resulting in a loose, porous matrix with irregular aggregate structure. The unusual physical structure and contaminant levels at the site made it unclear if the indigenous bacterial community would possess the complexity commonly observed for natural soils, and thus may limit potential for remediating the site using monitored natural attenuation. Bacterial diversity patterns were determined through 16S-TTGE and T-RFLP at depths of 0, 10, 20 and 30 m. Abundance and diversity patterns, as estimated by number and intensity of terminal restriction fragments and TTGE bands, varied among the 4 different depths, showing more complex patterns in deeper samples (20 and 30 m), which also contained greater concentrations of organic carbon. General diversity patterns were dominated by the phylum Proteobacteria (λ, β, and α divisions). These findings were reinforced by analysis of the culturable fraction able to use n-hexadecane as sole carbon source, in which the genera Acinetobacter sp. (λ-Proteobacteria) was dominant. This research offers new clues regarding bacterial diversity patterns through different depths in polluted environments with unique physicochemical conditions, suggesting that bacterial diversity profiles may be highly influenced by the nature of pollutants present. Additionally, results imply that the culturable fraction at the site has a very important role in the community.     

Tocopherol concentration in almond oil: genetic variation and environmental effects under warm conditions

The concentration of the different tocopherol homologues in almond kernel oil was determined in 17 almond cultivars grown in two different experimental orchards, in Spain and Morocco. The three main homologues showed a large variability, ranging from 210.9 to 553.4 mg/kg of oil for α-tocopherol, from 4.64 to 14.92 mg/kg for γ-tocopherol, and from 0.2 to 1.02 mg/kg for δ-tocopherol. The year effect was significant, independent of the experimental site, for all homologues and total tocopherol, the values of α-tocopherol, γ-tocopherol, and total tocopherol being higher in 2009 than in 2008, whereas the value of δ-tocopherol was higher in 2008. The location effect was also significant, the values of γ- and δ-tocopherol being higher in Spain than in Morocco, whereas for α-tocopherol the location effect was dependent on the genotype. These effects could not be explained by the temperature differences between sites, but probably other undetermined environmental factors might explain the effect of the location, such as rainfall and irrigation supplementation during fruit growing and ripening.