Differential Complexation between Zn2+ and Cd2+ with Fulvic Acid: A Computational Chemistry Study

Fulvic (FA) and humic acids (HA) from the solubilization of organic matter are significant agents of the complex of metallic ions in soil and water. Cadmium ions are important natural water pollutants which are discharged along with electroplating and zinc metallurgy liquid wastes, zinc and cadmium being always associated with isomorphic substitution. In this paper we study the complexes formed by Zn²⁺ and Cd²⁺ with fulvic acids, using computational chemistry. We carried out relative free energy calculations using a thermodynamic cycle and Free Energy Pertubation (FEP) and Density Functional Theory (DFT-B3LYP/6-31G**) methods. We also computed the interaction energies between orbitals from Natural Bond Order (NBO) calculations. Cd-FA complexes, octahedral with four water molecules in the coordination sphere are more stable than Zn-FA complexes, tetrahedral with two water molecules. This means that FA should be a better ligand for Cd²⁺ bioavailability and toxicity in natural aquatic environments.     

Granulomatous lymphadenitis caused by Talaromyces helicus in a Labrador Retriever

A 3-year-old spayed female Labrador Retriever was presented for right prescapular lymphadenomegaly. Examination of fine-needle aspirates and impression smears of the node revealed many short hyphal structures found within macrophages and extracellularly. Hyphae were approximately 3 μm in diameter, were irregularly septate with nonparallel walls, and had a small clear halo surrounding a partially stained basophilic internal structure. Hyphae were tapered on one end and had oval to pyriform swellings of 7-10 μm on the other, resulting in a bulbous appearance. Fungal elements stained positively with Gomori methenamine silver and Periodic acid-Schiff stains. The dog was euthanized at the owner's request, and necropsy revealed marked peripheral and visceral lymphadenomegaly. Histopathologic examination of lymph nodes confirmed granulomatous lymphadenitis with many fungal hyphae. Fungal culture yielded pure cultures of organisms that failed to produce ascospores or conidia precluding morphologic identification. PCR was performed using pan-fungal primers, ITS-1 and ITS-2, to amplify the intergenic spacer regions of ribosomal RNA; the PCR product was sequenced and a BLAST search of the GenBank databases at NCBI revealed 100% identity of the organism with Talaromyces helicus, the sexual form of Penicillium helicum. Talaromyces helicus has not previously been reported to cause disease in people or animals.     

Modelling bird distributions — a combined GIS and bayesian rule-based approach

Models to predict the breeding distribution of three species of birds in north-east England are described. The models use readily available data from the ornithological literature on the habitat preferences and life-history characteristics of the birds, together with satellite (land cover) and physiographic data. These data are linked via Bayesian decision-rules, and model predictions calculated at the landscape scale using a raster-based geographic Information System. Log-linear regressions of the predicted suitability of the landscape for the birds with observed sets of nest records were statistically significant for all three species. The robustness of the models to the effects of nonindependence of predictor (habitat) variables on Bayesian predictions was investigated using a perturbation method, which gave minor improvements to the accuracy of the predictions. The value of this modelling approach as a method of utilising published autoecological data to predict the landscape distribution of birds is discussed.     

Reattachment of tooth fragment: an in vitro study

Canine tooth fracture is common in dogs. Application of an esthetic and durable restoration may be challenging in veterinary dental practice. This study used traditional human dental laboratory methods to evaluate fracture strength of intact dog canine teeth and fractured teeth that had been restored by reattachment of the tooth fragment. The results showed that the teeth restored by reattachment of the tooth fragment supported a test load equal to 45.4 % of the load necessary to fracture intact canine teeth.     

The Ogallala Aquifer in Nebraska: Gray Literature (1891–2010)

The Ogallala Aquifer is a key water resource for several U. S. states. TransCanada, a Canadian company, proposes to construct the Keystone XL pipeline to transport tar sands crude oil from Alberta to refineries in Texas; one proposed route would bury the pipeline in the Aquifer, raising water quality and environmental concerns. A rich inventory of information about the Aquifer predates the current controversy. This article presents a key subset of an extensive, ongoing bibliography: 128 citations to gray literature about the Ogallala Aquifer in Nebraska, which are inaccessible online and/or held in only a few libraries. The authors present several examples to illustrate the relevance of this gray literature to current events, comment on difficulties encountered during the bibliographic harvest and the identification of this subset, and reiterate the need for planned preservation through digitization of historical (print) gray literature.     

Sustainable management, earthquake disturbances, and transient dynamics: modelling timber harvesting impacts in mixed-species forests

Context

There is strong interest in sustainable forest management systems that preserve characteristics of forests close to naturalness. Assessing the effectiveness of these systems is difficult because defining “natural” baselines from which impacts are estimated is challenging and because the influence of harvesting can have complex interactions with major natural disturbances.

Aims

We used SORTIE/NZ, an individual tree-based forest dynamics model, to understand how harvesting and earthquake disturbance affect the dynamics of a New Zealand podocarp–angiosperm forest.

Methods

Having parameterized SORTIE/NZ with extensive field data, we ran simulations for three natural dynamics scenarios (no disturbance and two earthquake scenarios) and then added podocarp harvesting scenario to each of these.

Results

Simulations suggest that this forest is experiencing transient dynamics, with a natural rise in the dominance of one species of slow-growing podocarp with and without earthquake. Harvesting podocarps strongly affected its increase in basal area.

Conclusion

Our results indicate that transient dynamics may occur in mixed podocarp forests and major disturbances may have complex interactions with management. Evaluating management impacts without accounting for these complex dynamics may be misleading. Models make predictions about transient trajectories that may help to evaluate these impacts.     

Assessing temporal variation of primary and ecosystem production in two Mediterranean forests using a modified 3-PG model

Context

Forest ecosystem carbon uptake is heavily affected by increasing drought in the Mediterranean region.

Aims

The objectives of this study were to assess the capacity of a modified 3-PG model to capture temporal variation in gross primary productivity (GPP), and ecosystem net carbon uptake (NEE) in two Mediterranean forest types.

Methods

The model was upgraded from a monthly (3-PG) to a daily time step (3-PG_day), and a soil water balance routine was included to better represent soil water availability. The model was evaluated against seasonal GPP and NEE dynamics from eddy covariance measurements.

Results

Simulated and measured soil water content values were congruent throughout the study period for both forest types. 3-PG_day effectively described the following: GPP and NEE seasonal patterns; the transition of forest ecosystems from carbon sink to carbon source; however, the model overestimated diurnal ecosystem respiration values and failed to predict ecosystem respiration peaks.

Conclusions

The model served as a rather effective tool to represent seasonal variation in gross primary productivity, and ecosystem net carbon uptake under Mediterranean drought-prone conditions. However, its semi-empirical nature and the simplicity inherent in the original model formulation are obstacles preventing the model working well for short-term daily predictions.     

Antimicrobial susceptibility and phylotyping profile of pathogenic <Emphasis Type="Italic">Escherichia coli</Emphasis> and <Emphasis Type="Italic">Salmonella enterica</Emphasis> isolates from calves and pigs in Minas Gerais,Brazil

The aims of the present study were to determine (i) the profiles of phylogroup and (ii) the antimicrobial susceptibility of pathogenic Escherichia coli strains isolated from calves, and of Salmonella spp. strains isolated from calves and pigs in Minas Gerais State, Brazil. Sixty-one pathogenic E. coli strains and Salmonella spp. (n?=?24) strains isolated from fecal samples of calves and Salmonella spp. (n?=?39) strains previously isolated from fecal samples of growing/finishing pigs were tested. The minimum inhibitory concentration (MIC) using the agar dilution method was determined for nalidixic acid, amikacin, amoxicillin, ampicillin, cefoxitin, norfloxacin, gentamicin, tetracycline, and trimethoprim-sulfamethoxazole. All E. coli isolates were susceptible to amikacin. Tetracycline was the antimicrobial that presented the higher frequency of resistance among E. coli strains, followed by ampicillin, trimethoprim-sulfamethoxazole, amoxicillin, nalidixic acid, norfloxacin, gentamicin, and cefoxitin. E. coli (n?=?61) strains isolated from calves belonged to different phylogroup namely, phylogroup A (n?=?26), phylogroup B1 (n?=?31), phylogroup E (n?=?3), and phylogroup F (n?=?1). Phylogroups B2, C, and D were not identified among the E. coli in the present study. All Salmonella spp. (n?=?24) strains isolated from fecal samples of calves were susceptible to amikacin, amoxicillin, ampicillin, norfloxacin, gentamicin, tetracycline, and trimethoprim-sulfamethoxazole. Resistance to nalidixic acid and cefoxitin was detected in 16.66 and 8.33 % of the Salmonella spp. strains, respectively. Among the Salmonella spp. (n?=?39) strains isolated from fecal samples of pigs, the higher frequency of resistance was observed to tetracycline, followed by amoxicillin, gentamicin, ampicillin, trimethoprim-sulfamethoxazole, nalidixic acid, cefoxitin, and norfloxacin. All strains were susceptible to amikacin. Forty-eight (78.68 %) of the E. coli strains were classified as multidrug-resistant, whereas among Salmonella spp. strains, the percentage of multidrug resistance was 57.14 %, being all multidrug-resistant strains isolated from pigs (92.30 %). The results from the present study indicate a high frequency of antimicrobial resistance among pathogenic E. coli strains isolated from calves and Salmonella spp. strains isolated from pigs and a high rate of susceptibility to most antimicrobials tested among Salmonella spp. strains isolated from calves. Our study highlights the presence of multidrug-resistant strains of E. coli and Salmonella spp. isolated from food-producing animals in Minas Gerais, Brazil.     

Microbial biomass as an antioxidant for tilapia feed

Microbial biomass (MB) produced by different industries is thought to be a beneficial supplement in fish feed due to high contents of antioxidants and pigments. However, little is known about their impact on fish health. In this experiment, 960 tilapia (26.84 ± 1.03 g) were fed one of eight experimental diets—a control diet with no MB (C), a control diet with vitamin E (VE) and six diets with three types of MB at two concentrations (0.25% and 0.5%): Rubrivivax gelatinosus (RG25 and RG50), Spirulina platensis (SP25 and SP50) and Saccharomyces cerevisiae (SC25 and SC50). Adding MB to diets decreased plasma total oxidant status, malonaldehyde and leucocyte respiratory burst; increased the total antioxidant status; and did not affect the blood biochemical parameters. In flesh, the use of the MB lowered the thiobarbituric acid‐reactive substances and increased redness (except for SC) and carotenoid deposition (except SC25). So, it was concluded that the use of the MB provided an antioxidant effect in tilapia blood plasma, decreased lipid oxidation and increased pigmentation and carotenoid deposition in the fish flesh, without imparting a negative impact on the animals’ health.     

The role of germination microsite in the establishment of sugar pine and Jeffrey pine seedlings

Mature shrubs can provide microhabitats that are beneficial to tree seedling growth and development. Sugar pine trees (Pinus lambertiana) grow in a narrow zone on the eastern slope of the Carson Range in extreme western Nevada, whereas Jeffrey pine (Pinus jeffreyi) is the dominant tree species in the region, an area extensively disturbed by wild fire. This study compares seedling establishment of sugar pine and Jeffrey pine relative to mature shrubs. In the fall of 2002 (cohort 1) and 2003 (cohort 2), 13,600 seeds of both species were planted in wire mesh enclosures, at three sites, under a variety of microhabitat treatments: under shade and in the open, under two species of shrub cover, and with and without plant litter. Seedlings were monitored for survival through two growing seasons. Even though more sugar pine seedlings emerged, more Jeffrey pine seedlings survived, and Jeffrey pine was the more drought tolerant species, better suited for the xeric climate found in the Carson Range. Litter slightly hindered seedling emergence but had no effect on survival and there was no significant species × litter interaction. Supplemental water facilitated survival in all treatments with highest survival in shade treatments. Sugar pine seedlings showed a significant increase in survival over Jeffrey pine seedlings with the addition of water, particularly in open treatments and more of both species survived under manzanita shrubs with water. The highest seedling mortality occurred when shrub canopy was removed, and seedlings experienced the effect of full sun and competition for soil water. For either species, microhabitat is a significant factor in determining success or failure in rehabilitation efforts after disturbance.