Manganese uptake and partitioning between the tissue of the anemone host Exaiptasia pallida and Symbiodinium spp., including assessment of stress and recovery.

Manganese (Mn) is essential for global steel and Mn-iron (Fe) alloy production. The human health effects of elevated Mn concentrations have been well established, but studies on its impact on marine invertebrates are limited. This study is the first to investigate Mn uptake in the sea anemone Exaiptasia pallida after chronic exposure (0.5, 1, 10, and 100 mg/L) for 24-d. Following exposure, E. pallida were transferred to ambient seawater for 6-d to assess Mn depuration. Mn accumulation and partitioning in host tissue and symbionts (Symbiodinium spp.), tentacle retraction, and symbiont cell density were measured during exposure and depuration. Mn concentrations were substantially higher in symbionts than tissue in all treatments after 24-d. No significant difference was observed for symbiont cell density after Mn exposure. Tentacle retractions were significantly higher in all Mn exposed treatments than controls at all time points. Mn depuration was observed for both tissue and symbionts but was more rapid in symbionts. This study reveals that Symbiodinium spp. can play a role in Mn uptake and depuration in anemones, but Mn loading does not affect cell density. These results help understand metal uptake and depuration in complex relationships between Symbiodinium spp. and other host taxa like corals.

Comparative assessment of bioremediation approaches to highly recalcitrant PAH degradation in a real industrial polluted soil.

High recalcitrant characteristics and low bioavailability rates due to aging processes can hinder high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) bioremediation in real industrial polluted soils. With the aim of reducing the residual fraction of total petroleum hydrocarbons (TPH) and (HMW-PAHs) in creosote-contaminated soil remaining after a 180-d treatment in a pilot-scale biopile, either biostimulation (BS) of indigenous microbial populations with a lignocellulosic substrate (LS) or fungal bioaugmentation with two strains of white-rot fungi (WRF) (i.e., Trametes versicolor and Lentinus tigrinus) were comparatively tested. The impact of bivalent manganese ions and two mobilizing agents (MAs) (i.e., Soybean Oil and Brij 30) on the degradation performances of biostimulated and bioaugmented microcosms was also compared. The results reveal soil colonization by both WRF strains was clearly hampered by an active native soil microbiota. In fact, a proper enhancement of native microbiota by means of LS amendment promoted the highest biodegradation of HMW-PAHs, even of those with five aromatic rings after 60 days of treatment, but HMW-PAH-degrading bacteria were specifically inhibited when non-ionic surfactant Brij 30 was amended. Effects of bioaugmentation and other additives such as non-ionic surfactants on the degrading capability of autochthonous soil microbiota should be evaluated in polluted soils before scaling up the remediation process at field scale.

Risk assessment of an essential element: manganese.

Manganese (Mn) is an essential element for humans, animals, and plants and is required for growth, development, and maintenance of health. Mn is present in most tissues of all living organisms and is present naturally in rocks, soil, water, and food. High-dose oral, parenteral, or inhalation exposures are associated with increased tissue Mn levels that may lead to development of adverse neurological, reproductive, or respiratory effects. Manganese-induced clinical neurotoxicity is associated with a motor dysfunction syndrome commonly referred to as manganism. Because Mn is an essential element and absorption and excretion are homeostatically regulated, a reasonable hypothesis is that there should be no adverse effects at low exposures. Therefore, there should be a threshold for exposure, below which adverse effects may occur only rarely, if at all, and the frequency of occurrence of adverse effects may increase with higher exposures above that threshold. Lowest-observed-adverse-effect levels (LOAELs), no-observed-adverse-effect levels (NOAELs), and benchmark dose levels (BMDs) have been derived from studies that were conducted to evaluate subclinical neurotoxicity in human occupational cohorts exposed to Mn. Although there is some uncertainty about the predictive value of the subclinical neuromotor or neurobehavioral effects that were observed in these occupational cohort studies, results of the neurological tests were used in risk assessments to establish guidelines and regulations for ambient air levels of Mn in the environment. A discussion of the uncertainties associated with these tests is provided in this review. The application of safety and uncertainty factors result in guidelines for ambient air levels that are lower than the LOAELs, NOAELs, or BMDs from occupational exposure studies by an order of magnitude, or more. Specific early biomarkers of effect, such as subclinical neurobehavioral or neurological changes or magnetic resonance imaging (MRI) changes, have not been established or validated for Mn, although some studies attempted to correlate certain biomarkers with neurological effects. Pharmacokinetic studies with rodents and monkeys provide valuable information about the absorption, bioavailability, and tissue distribution of various Mn compounds with different solubilities and oxidation states in different age groups. These pharmacokinetic studies showed that rodents and primates maintain stable tissue Mn levels as a result of homeostatic mechanisms that tightly regulate absorption and excretion of ingested Mn and limit tissue uptake at low to moderate levels of inhalation exposure. In addition, physiologically based pharmacokinetic (PBPK) models are being developed to provide for the ability to conduct route-to-route extrapolations, evaluate nasal uptake to the central nervous system (CNS), and determine life-stage differences in Mn pharmacokinetics. Such models will facilitate more rigorous quantitative analysis of the available human pharmacokinetic data for Mn and will be used to identify situations that may lead to increased brain accumulation related to altered Mn kinetics in different human populations, and to develop quantitatively accurate predictions of elevated Mn levels that may serve as a basis of dosimetry-based risk assessments. Such dosimetry-based risk assessments will permit for the development of more scientifically refined and robust recommendations, guidelines, and regulations for Mn levels in the ambient environment and occupational settings.

Essentiality, toxicity, and uncertainty in the risk assessment of manganese.

Risk assessments of manganese by inhalation or oral routes of exposure typically acknowledge the duality of manganese as an essential element at low doses and a toxic metal at high doses. Previously, however, risk assessors were unable to describe manganese pharmacokinetics quantitatively across dose levels and routes of exposure, to account for mass balance, and to incorporate this information into a quantitative risk assessment. In addition, the prior risk assessment of inhaled manganese conducted by the U.S. Environmental Protection Agency (EPA) identified a number of specific factors that contributed to uncertainty in the risk assessment. In response to a petition regarding the use of a fuel additive containing manganese, methylcyclopentadienyl manganese tricarbonyl (MMT), the U.S. EPA developed a test rule under the U.S. Clean Air Act that required, among other things, the generation of pharmacokinetic information. This information was intended not only to aid in the design of health outcome studies, but also to help address uncertainties in the risk assessment of manganese. To date, the work conducted in response to the test rule has yielded substantial pharmacokinetic data. This information will enable the generation of physiologically based pharmacokinetic (PBPK) models capable of making quantitative predictions of tissue manganese concentrations following inhalation and oral exposure, across dose levels, and accounting for factors such as duration of exposure, different species of manganese, and changes of age, gender, and reproductive status. The work accomplished in response to the test rule, in combination with other scientific evidence, will enable future manganese risk assessments to consider tissue dosimetry more comprehensively than was previously possible.

A novel and efficient and low-cost methodology for purification of Macrotyloma axillare (Leguminosae) seed lectin.

The N-acetyl-galactosamine specific lectin from Macrotyloma axillare seeds (LMA) was purified by precipitation and ion exchange chromatography. The LMA 0.2 mol L(-1) fraction showed hemagglutinating activity on erythrocytes A1. The results for molecular mass determinations were about 28 kDa. The LMA pH-dependent assays showed best hemagglutinating activity at pH 6.0-8.0; being decreased at acidic/alkaline conditions and by EDTA treatment. LMA is a tetramer at pH 8.2 and a dimer at pH 4.0. Human erythrocytes from ABO system confirmed the A1 specificity for LMA. This new methodology is useful and easy, with low costs, for lectin purification in large amounts.

[Comparative stability assessment of laccases from the basidiomycetes Coriolus hirsutus and Coriolus zonatus in the presence of effectors]. / Sravnitel'noe izuchenie stabil'nosti lakkaz iz bazidiomitsetov Coriolus hirsutus i Coriolus zonatus v prisutstvii éffectorov.

Stability characteristics of the laccases of the basidiomycetes Coriolus hirsutus and Coriolus zonatus were measured comparatively at temperatures 25 and 40 degrees C in the presence of various effectors (proteins, salts, polyalcohols, polyacids, and polyelectrolytes). Stabilization effects of cations on the laccases from C. hirsutus and C. zonatus decreased in the descending series Cu2+ > Mg2+ > Ca2+ and Ca2+ > Mg2+ > Mn2+, respectively. Tween 20 caused insignificant stabilization of the two enzymes. The C. zonatus laccase was also insignificantly stabilized as a result of treatment with bovine serum albumin. The enzymatic activity of the laccase preparations from C. hirsutus and C. zonatus was conserved virtually completely after vacuum drying (84 and 93%, respectively). The most effective stabilizer of the C. hirsutus laccase was found to be dextran (17 kD). Dry preparations treated with this agent conserved up to 95% of the enzymatic activity. The most effective stabilizer of the C. zonatus was polyacrylic acid (102% of the initial activity).

[The treatment of wastes from antibiotic manufacture by using pyrolusite]. / Obrabotka otkhodov proizvodstva antibiotikov s ispol'zovaniem piroliuzita.

Data on laboratory studies with real liquid sewage from antibiotic manufacture are presented. Two schemes are discussed: treatment of the sewage in an electrolysis plant followed by its afterpurification either in a column with pyrolusite or during a joint process of electrochemical purification with catalyst location on the plant bottom under the electrodes. The afterpurification of electrochemically treated liquid sewage on waste pyrolusite can provide and additional effect i.e. lower consumption of oxygen and decoloration at average by 15 and 25 per cent respectively.

Assessment of the male reproductive system in the preweanling rat following Mn3O4 exposure.

Long-Evans rat pups were dosed orally from birth to 21 d with particulate Mn3O4 to obtain a daily dose of 0, 71, or 214 micrograms Mn/body weight . d. Assessments of the hypothalamic, pituitary, or testicular functions were determined by measuring the endogenous or stimulated serum concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and/or testosterone (T) at 21 or 28 d of age. Body, testes, and seminal vesicles weight and tissue concentrations of Mn were also evaluated. Only slight Mn treatment effects were seen in body and testes weights. No effects were seen either on unstimulated or stimulated FSH or LH serum concentrations. Although no Mn treatment effects were seen on endogenous or 2 h human chorionic gonadotropin (hCG) stimulate serum T concentrations, there was a reduction in the serum T following 7 d of hCG stimulation. The hypothalamic Mn concentrations in animals with these reproductive effects were three times those where alterations in the dopaminergic pathway have been reported. However, no indication of hypothalamic or pituitary malfunction was found. These results suggest that the site of Mn damage that causes depression of sustained serum T concentration is in the testicular Leydig cell.

Spontaneous calcium release from sarcoplasmic reticulum. Assessment of other ionic influences.

A form of spontaneous Ca2+ release from purified light sarcoplasmic reticulum has been recently described (Palade, P., Mitchell, R. D., and Fleischer, S. (1983) J. Biol. Chem. 258, 8098-8107). It is characterized by rapid Ca2+ efflux (1-10 mumol/min X mg protein) which begins only after a delay following preloading and depletion of extravesicular Ca2+. In the present study, the influences of a number of ionic factors modulating the spontaneous calcium release phenomenon are described. The divalent metal ions Mn2+ and Sr2+ and higher external [Mg2+] inhibit release. Mn2+ appears to inhibit from outside, whereas Sr2+ must be taken up to inhibit. Decreasing the phosphate concentration during preloading eliminates spontaneous release, but it can be partially restored with salts of other nonprecipitating anions. No such release was obtained with other Ca2+-precipitating anions, i.e. pyrophosphate, oxalate, and fluoride. The release characteristics are strongly dependent on the monovalent cation present. Spontaneous Ca2+ release is optimal at pH 6.8-7.0 and decreases sharply at higher and lower pH. Ca2+ release can be enhanced by addition, during the lag period, of concentrated salt solutions consisting of more permeant cations than anions, which may indicate that an inside positive membrane potential enhances the rate of calcium release. Spontaneous Ca2+ release can take place in the presence of sucrose, and Ca2+ efflux is not accompanied by a corresponding efflux of preloaded sucrose, demonstrating that the vesicles remain sealed during spontaneous release. The spontaneous Ca2+ release process is distinct from several other forms of Ca2+ release from sarcoplasmic reticulum.

Differential regulation of the mu-, delta-, and kappa-opiate receptor subtypes by guanyl nucleotides and metal ions.

The effects of Na+, guanyl-5'-yl imidodiphosphate (Gpp(MH)p), and Mn2+ on the binding of dihydromorphine, ethylketocyclazocine, D-Ala2, D-Leu5-enkephalin, and diprenorphine to the opiate receptor were investigated. Three distinct binding sites, mu, delta, and kappa sites, were identified with the use of multiple tracer displacement curves. Moreover, this approach was used to determine the effects of Gpp (NH)p and metal ions on each individual binding site. At the mu and delta sites, Na+ and Gpp(NH)p each decreased and Mn2+ increased agonist binding affinities, with the exception of D-Ala2, D-Leu-enkephalin affinity which was not affected by Gpp(NH)p. None of these conditions markedly altered dihydromorphine and D-Ala2, Leu5-enkephalin binding to kappa sites, whereas the affinity of ethylke-tocyclazocine for kappa sites was decreased by Gpp(NH)p. Sodium ions lowered the capacity of mu sites and Gpp(NH)p reduced that of delta sites, while both agents increased the capacity of apparent kappa sites. These results demonstrate that each of the kinetically distinguishable binding sites is regulated differentially by metal ions and guanyl nucleotides. Simultaneous addition of Na+ and Gpp(NH)p greatly reduced the binding affinity of all three agonists at their respective high affinity sites (dihydromorphine at the mu site, D-Ala2, D-Leu5-enkephalin at the delta site, and ethylketocyclazocine at the kappa and mu sites). This result confirms previous observations that agonist binding is characterized by a large affinity reduction in the presence of both Na+ and guanyl nucleotides, and it extends this concept to each of the opiate receptor subtypes.