Microscale variation in<Emphasis Type="Italic"> Aat</Emphasis> (aspartate aminotransferase) is supported by activity differences between upper and lower shore allozymes of<Emphasis Type="Italic"> Littorina saxatilis</Emphasis>

The role of natural selection in maintaining inherited variation in morphological characters is indisputable. In contrast, genetic variation in allozyme loci is mostly assumed neutral or under weak selection, although enzyme functions are critical to central metabolic processes. A locus coding for aspartate aminotransferase (AAT) is polymorphic with two alleles in the rocky shore gastropod Littorina saxatilis. One allele (Aat ¹²⁰ ) is most frequent (0.8–0.9) in upper shore subpopulations, while the other (Aat ¹⁰⁰ ) dominates (0.7–0.8) lower shore subpopulations only meters below. Earlier studies show this variation to be maintained by divergent selection, but the mechanism is unknown. We measured enzyme activities in AAT extracts from individuals of known Aat genotype in populations from two islands and at three different temperatures. In all treatments lower shore homozygotes (Aat ^100/100 ) had higher enzyme activity than upper shore homozygotes (Aat ^120/120 ), with heterozygotes having intermediate levels of activity. AAT has a central role in anaerobic energy production in marine mollusks during low-tide periods of emergence, and it might appear surprising that upper shore snails, which are most likely to be emerged, have lower enzyme activity. However, upper shore snails are forced to survive long periods of desiccation, and a low metabolic rate will help to conserve limited resources of energy and nutrients and reduce accumulation of waste products.Communicated by L. Hagerman, Helsingør     

Photochemical degradation of nonylphenol in aqueous solution：The impact of pH and hydroxyl radical promoters

The degradation of nonylphenol (NP) in aqueous solution with UV, H₂O₂/UV, and Fenton/photo-Fenton processes was studied. The efficacy of direct and hydrogen peroxide photolysis proved to be dependent on the pH value. The addition of H₂O₂ to UV treatment improved NP degradation. The application of UV photolysis and the H₂O₂/UV system at pH 7 resulted in low pseudo first-order rate constants at 10^-4 sec^-1. In the experiments at elevated pH values the pseudo-first order rate constants increased to 10^-3 sec^-1. The efficacy of the Fenton process was lower in comparison with UV and hydrogen peroxide photolysis. The addition of UV irradiation to the H₂O₂/Fe²⁺ system substantially improved NP degradation efficacy. In terms of performance, the photo-Fenton process was similar to the H₂O₂/UV process. The most favourable process for complete nonylphenol degradation considering both operational cost and treatment efficacy was H₂O₂/UV at pH 11 and 250 mol/L H₂O₂.     

Blood markers among residents from a coal mining area

Environmental Science and Pollution Research - Coal extraction and processing generate environmental contamination, which has several negative impacts on human health. Hematological and biochemical...     

Protective effect of gamma-oryzanol against manganese-induced toxicity in Drosophila melanogaster

Environmental Science and Pollution Research - Manganese (Mn) is an essential element that, in excess, seems to be involved in the development of different neurodegenerative conditions....     

Unlikely lead-bearing phases in river and estuary sediments near an ancient mine (Huelgoat,Brittany, France)

Environmental Science and Pollution Research - Anthropocene mineral diversity is the result of the purification of metals naturally combined with other chemical elements in natural environment....     

Selective sorptive removal of Methyl Red from individual and binary component solutions by mesoporous organosilicas of MCM-41 type

Organosilicas with chemically immobilized 3-aminopropyl and Methyl Red-containing surface groups were prepared by sol-gel condensation of tetraethyl orthosilicate and (3-aminopropyl)triethoxysilane in the presence of dye as part of the mixed micelles or dye-containing silane as silica source. The hexagonally arranged mesoporous structure of synthesized materials was confirmed by low-temperature nitrogen adsorption-desorption, x-ray diffraction, and TEM studies. Chemical composition of MCM-41-type organosilicas was established by FT-IR spectroscopy and chemical analysis of surface layer. Sorption of Methyl Red by organosilicas was studied from diluted phosphate buffer solutions in dependence of medium pH, duration of contact, and equilibrium concentration of dye. It was found that effective removal of Methyl Red takes place at pH values within a range of 2.5?5. Kinetic curves of Methyl Red sorption on organosilicas were analyzed by the Lagergren, Ho-McKey, and Weber-Morris kinetic models. It was found that the pseudo-second-order model fits the kinetics of Methyl Red sorption on all synthesized materials and the intraparticle diffusion is not the only one mechanism controlling the rate of Methyl Red sorptive removal. The parameters of equilibrium sorption of Methyl Red on organosilicas of MCM-41 type were calculated using Langmuir, Freundlich, Redlich-Peterson, and Brunauer-Emmett-Teller models. Sorption of acid dyes with geometry similar or substantially different from Methyl Red on mesoporous silicas was studied from single and binary component mixtures in aqueous solutions with pH 4.8 and 5.5. It was found that selective sorption process is highly dependent on the structural characteristics and protolytic state of silica surface as well as acid dye.     

Deflective effect and the effect of prey detectability on anti-predator function of eyespots

Eyespots (patterns of roughly concentric rings) are often thought to have an anti-predator function. Previous experiments have lent support for the intimidation hypothesis by demonstrating a deterring effect of eyespots, but so far there is little evidence for the deflective effect (direction of attacks toward less vital body parts). We studied predators’ responses towards large and small eyespots and towards prey with no, one, or a pair of eyespots and if this response is influenced by whether or not prey blend into background. In two experiments, we used artificial, triangular prey items and blue tits (Cyanistes caeruleus) as predators. In experiment 1, we found evidence for the deflective effect of small but not large eyespots, independent of whether the prey was presented on a concealing or exposing background. In experiment 2, we found that predators avoided the prey with a pair of small eyespots more than the prey without eyespots, but interestingly, we only found this deterring effect on the concealing background. There was no difference in attacks between the prey with one large and two small or one large and no eyespots. We conclude that deflective function may select for eyespots, and background may influence the deterring function of eyespots.     

Prenatal diagnosis of Pelizaeus-Merzbacher disease: detection of proteolipid protein gene duplication by quantitative fluorescent multiplex PCR

A prenatal diagnosis of Pelizaeus-Merzbacher disease (PMD) resulting from proteolipid protein gene (PLP) duplication was performed by a quantitative fluorescent multiplex PCR method. PLP gene copy number was determined in the proband, the pregnant mother, the male fetus and two aunts. Small amounts of genomic DNA extracted from peripheral blood and from chorionic villi were used. The fetus, in common with the proband, was identified as PMD-affected being a carrier of the PLP gene duplication, inherited from the mother, while the two aunts were non-carriers. The data obtained were confirmed by segregation analysis of a PLP-associated dinucleotide-repeat polymorphism amplified by the same multiplex PCR. Copyright © 2001 John Wiley & Sons, Ltd.     

Tire debris organic extract affects Xenopus development

Tire debris (TD) and its organic components were identified as a main source of PM10 atmospheric and water pollution. Because few data are available on the embryotoxic effects of TD organic components, the lethal and teratogenic potential of tire debris organic extract (TDOE) was evaluated using the frog embryo teratogenesis assay-Xenopus (FETAX), coupled with a histopathological screening of the survived larvae. From stage 8 to stage 47, Xenopus laevis embryos were exposed to TDOE at concentrations of 50, 80, 100, 120 and 140 mg/L. The results showed 50 mg/L TDOE to be the non-observable effect concentration (NOEC). TDOE mortality at 80 mg/L was significantly higher than the control, but did not increase further with higher concentrations. A good concentration-response was observed for percentages of malformed larva and from 80 mg/L on these percentages were significantly higher than the control. Therefore, probit analysis gave a 144.6 mg/L TC50. At 120 and 140 mg/L, many larvae were plurimalformed. The most frequent alterations observed were abnormal gut coiling, microphthalmia, monolateral anophthalmia, and narrowing eyes. The histological screening mainly revealed ocular malformations such as double retina, retina nervous cell layer coiling, and altered lens. Moreover severe vacuolisation and necrosis were scored in liver and axial musculature. These results strongly support the assumption that TDOE is a powerful teratogen for X. laevis.