Effects of repeated-low level sodium chlorate administration on ruminal and fecal coliforms in sheep

Abstract

The objective of this study was to evaluate the efficacy of oral sodium chlorate administration on reducing total coliform populations in ewes. A 30% sodium chlorate product or a sodium chloride placebo was administered to twelve lactating Dorper X Blackbelly or Pelibuey crossbred ewes averaging 65 kg body weight. The ewes were adapted to diet and management. Ewes were randomly assigned (4/treatment) to one of three treatments which were administered twice daily by oral gavage for five consecutive days: a control (TC) consisting of 3 g sodium chloride/animal/d, a T3 treatment consisting of 1.8 g of sodium chlorate/animal/d, and a T9 treatment consisting of 5.4 g sodium chlorate/animal/d; the latter was intended to approximate a lowest known effective dose. Ruminal samples collected by stomach tube and freshly voided fecal samples were collected daily beginning 3 days before treatment initiation and for 6 days thereafter. Contents were cultured quantitatively to enumerate total coliforms. There were no significant differences in total coliform numbers (log₁₀ cfu/g) in the feces between treatments (P = 0.832). There were differences (P < 0.02) in ruminal coliform counts (log₁₀ cfu/mL) between treatments (4.1, 4.3 and 5.0 log₁₀/mL contents in TC, T3 and T9 Treatments, respectively) which tended to increase from the beginning of treatment until the 5th day of treatment (P < 0.05). Overall, we did not obtain the expected results with oral administration of sodium chloride at the applied doses. By comparing the trends in coliform populations in the rumen contents in all treatments, there was an increase over the days. The opposite trend occurred in the feces, due mainly to differences among rumen contents and feces in ewes administered the T9 treatment (P = 0.06). These results suggest that the low chlorate doses used here were suboptimal for the control of coliforms in the gastrointestinal tract of ewes.     

Core–shell magnetite-silica dithiocarbamate-derivatised particles achieve the Water Framework Directive quality criteria for mercury in surface waters

The sorption capacity of nanoporous titanosilicate Engelhard titanosilicate number 4 (ETS-4) and silica-coated magnetite particles derivatised with dithiocarbamate groups towards Hg(II) was evaluated and compared in spiked ultra-pure and spiked surface-river water, for different batch factors. In the former, and using a batch factor of 100 m³/kg and an initial Hg(II) concentrations matching the maximum allowed concentration in an effluent discharge, both materials achieve Hg(II) uptake efficiencies in excess of 99 % and a residual metal concentration lower than the guideline value for drinking water quality. For the surface-river water and the same initial concentration, the Hg(II) uptake efficiency of magnetite particles is outstanding, achieving the quality criteria established by the Water Framework Directive (concerning Hg concentration in surface waters) using a batch factor of 50 m³/kg, while the efficiency of ETS-4 is significantly inferior. The dissimilar sorbents’ Hg(II) removal efficiency is attributed to different uptake mechanisms. This study also highlights the importance of assessing the effective capacity of the sorbents under realistic conditions in order to achieve trustable results.     

The protective effect of job satisfaction in health,happiness, well-being and self-esteem

The purpose of this article is to analyze the possible effects of job satisfaction on mental and physical health, happiness, subjective well-being and self-esteem. A total of 971 Portuguese-speaking adults participated in this study. Most participants reported high rates of satisfaction with their colleagues, the nature of their work and leadership, while reporting dissatisfaction with regard to salaries and promotions. Results indicated the existence of the protector effect of job satisfaction for health, happiness, subjective well-being and self-esteem, in addition to reinforcing the importance of maintaining a positive evaluation of one’s work. As a practical implication, the results may suggest that the effects of personnel management policies which emphasize job satisfaction could potentially lead to improvements in levels of health, happiness, subjective well-being and workers’ self-esteem, all of which are factors that can potentially improve organizational performance. The study also considered its limitations and the possibility for future investigation.     

Bioadsorption and bioaccumulation of chromium trivalent in Cr(III)-tolerant microalgae: A mechanisms for chromium resistance

Anthropogenic activity constantly releases heavy metals into the environment. The heavy metal chromium has a wide industrial use and exists in two stable oxidation states: trivalent and hexavalent. While hexavalent chromium uptake in plant cells has been reported that an active process by carrying essential anions, the cation Cr(III) appears to be taken up inactively. Dictyosphaerium chlorelloides (Dc1M), an unicellular green alga is a well-studied cell biological model organism. The present study was carried out to investigate the toxic effect of chromium exposures on wild-type Cr(III)-sensitive (Dc1M^wt) and Cr(III)-tolerant (Dc1M^Cr(III)R30) strains of these green algae, and to determine the potential mechanism of chromium resistance. Using cell growth as endpoint to determine Cr(III)-sensitivity, the IC₅₀₍₇₂₎ values obtained show significant differences of sensitivity between wild type and Cr(III)-tolerant cells. Scanning electron microscopy (SEM) showed significant morphological differences between both strains, such as decrease in cell size or reducing the coefficient of form; and transmission electron microscopy (TEM) revealed ultrastructural changes such as increased vacuolization and cell wall thickening in the Cr(III)-tolerant strain with respect to the wild-type strain. Energy dispersive X-ray analysis (SEM/XEDS) revealed that Cr(III)-tolerant D. chlorelloides cells are able to accumulate considerable amounts of chromium distributed in cell wall (bioadsorption) as well as in cytoplasm, vacuoles, and chloroplast (bio-accumulation). Morphological changes of Cr(III)-tolerant D. chlorelloides cells and the presence of these electron-dense bodies in their cell structures can be understood as a Cr(III) detoxification mechanism.     

Production and partial characterization of bioemulsifier from a chromium-resistant actinobacteria

Surface-active compounds such as synthetic emulsifiers have been used for several decades, both for the degradation of hydrocarbons and increasing desorption of soil-bound metals. However, due to their high toxicity, low degradability, and production costs unaffordable for use in larger ecosystems, synthetic emulsifiers have been gradually replaced by those derived from natural sources such as plants or microbes. In previous studies, the bacterium Streptomyces sp. MC1 has shown the ability to reduce and/or accumulate Cr(VI), a highly promising advance in the development of methods for environmental clean-up of sites contaminated with chromium. Here, new studies on the production of emulsifier from this strain are presented. The cultivation factors that have a significant influence on emulsifier biosynthesis, as well as the interactions among them, were studied by factorial design. Based upon optimization studies, maximum bioemulsifier production was detected in the culture medium having an initial pH of 8 with phosphate 2.0 g L^?1 and Ca⁺² 1.0 g L^?1 added, with an emulsification index about 3.5 times greater compared to the basal value. Interestingly, in the presence of 5.0 g L^?1 Cr(VI), Streptomyces sp. MC1 retained about 65% of its emulsifier production ability. Partially purified emulsifier presented high thermo-stability and partial water solubility. These findings could have promising future prospects for the remediation of organic- and metal-contaminated sites.     

The Trifinio Region: a case study of transboundary forest change in Central America

Strategic planning to increase forest cover in Central American transboundary areas of the Mesoamerican Biological Corridor requires understanding land-cover and land-use change trends and drivers. We estimated forest cover change from remotely sensed land-cover and land-use classifications from 1986, 2001, and 2010, in the tri-national Trifinio Region, bordering El Salvador, Guatemala, and Honduras. Our analysis spanned subnational, national, regional, and protected border areas. We determined correlations with direct drivers of deforestation, developing a multilevel linear regression model. Higher population density significantly correlated with deforestation; coffee, agroforestry, and pasture replaced forests. The tri-national park retained forests compared to neighboring areas, but additionality requires more research. The literature on drivers suggests similar processes and factors in other tropical regions. Forest cover governance efficacy is highly variable. Results indicate relationship between governance and forest cover though more comprehensive understanding of this complex region is needed to determine their causality.     

Extractability and mobility of mercury from agricultural soils surrounding industrial and mining contaminated areas

This study focussed on a comparison of the extractability of mercury in soils with two different contamination sources (a chlor-alkali plant and mining activities) and on the evaluation of the influence of specific soil properties on the behaviour of the contaminant. The method applied here did not target the identification of individual species, but instead provided information concerning the mobility of mercury species in soil. Mercury fractions were classified as mobile, semi-mobile and non-mobile. The fractionation study revealed that in all samples mercury was mainly present in the semi-mobile phase (between 63% and 97%). The highest mercury mobility (2.7 mg kg(-1)) was found in soils from the industrial area. Mining soils exhibited higher percentage of non-mobile mercury, up to 35%, due to their elevated sulfur content. Results of factor analysis indicate that the presence of mercury in the mobile phase could be related to manganese and aluminium soil contents. A positive relation between mercury in the semi-mobile fraction and the aluminium content was also observed. By contrary, organic matter and sulfur contents contributed to mercury retention in the soil matrix reducing the mobility of the metal. Despite known limitations of sequential extraction procedures, the methodology applied in this study for the fractionation of mercury in contaminated soil samples provided relevant information on mercury's relative mobility.     

Hemolysis,Fish Mortality,and LC-ESI-MS of Cultured Crude and Fractionated Golden Alga (Prymnesium parvum)1

Schug, Kevin A., Theodore R. Skingel, Sandra E. Spencer, Carlos A. Serrano, Cuong Q. Le, Christopher A. Schug, Theodore W. Valenti, Jr., Bryan W. Brooks, Laura D. Mydlarz, and James P. Grover, 2010. Hemolysis, Fish Mortality, and LC-ESI-MS of Cultured Crude and Fractionated Golden Alga (Prymnesium parvum). Journal of the American Water Resources Association (JAWRA) 46(1):33-44. DOI: 10.1111/j.1752-1688.2009.00389.x Abstract: Erythrocyte lysis and fish mortality assays, in combination with high performance liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) analysis, were investigated for bioassay-guided fractionation of cultured golden alga (Prymnesium parvum). Intracellular constituents from isolated cell pellets and extracellular supernatant growth medium were fractionated by a variety of common separation modes, including reversed phase and normal phase solid phase extraction step fractionation procedures. For reversed phase fractionation of extracellular growth medium, one fraction was obtained that displayed hemolytic activity and adversely affected fish survival. Effective dose concentrations for this sample were similar in both assays and the LC-ESI-MS analysis of the fraction showed a number of mass spectral signals which were distinct to this fraction. Fractions obtained from separation of an ethanol extract of the lyophilized cell pellet provided one sample that was highly hemolytic, but not toxic to fish. Discrepancies such as this, along with notable fish behavioral responses from other nonhemolytic cell pellet fractions, problems with the use of unbonded silica gel for fractionation, and misleading mass spectral signatures are interesting in the context of our current understanding of P. parvum toxicity and remain to be investigated further. This work provides an account of ongoing research aimed toward comprehensive elucidation of toxic constituents produced by golden alga for the purpose of providing a better understanding and means to potentially remediate the ecological impact of this harmful bloom organism.     

Evaluation of aquatic plants for removing polar microcontaminants: a microcosm experiment

Microcosm wetland systems (5 L containers) planted with Salvinia molesta, Lemna minor, Ceratophyllum demersum, and Elodea canadensis were investigated for the removal of diclofenac, triclosan, naproxen, ibuprofen, caffeine, clofibric acid and MCPA. After 38 days of incubation, 40-99% of triclosan, diclofenac, and naproxen were removed from the planted and unplanted reactors. In covered control reactors no removal was observed. Caffeine and ibuprofen were removed from 40% to 80% in planted reactors whereas removals in control reactors were much lower (2-30%). Removal of clofibric acid and MCPA were negligible in both planted and unplanted reactors. The findings suggested that triclosan, diclofenac, and naproxen were removed predominantly by photodegradation, whereas caffeine and naproxen were removed by biodegradation and/or plant uptake. Pseudo-first-order removal rate constants estimated from nonlinear regressions of time series concentration data were used to describe the contaminant removals. Removal rate constants ranged from 0.003 to 0.299 d(-1), with half-lives from 2 to 248 days. The formation of two major degradation products from ibuprofen, carboxy-ibuprofen and hydroxy-ibuprofen, and a photodegradation product from diclofenac, 1-(8-Chlorocarbazolyl)acetic acid, were followed as a function of time. This study emphasizes that plants contribute to the elimination capacity of microcontaminants in wetlands systems through biodegradation and uptake processes.