Distribution and variation of hemagglutinating activity in the hemolymph of Biomphalaria glabrata

A sensitive hemagglutination assay utilizing glutaraldehyde-fixed trypsinized calf erythrocytes (GTC) is described to test for agglutinin levels in hemolymph and albumen gland extracts from nine populations of Biomphalaria glabrata, and from B. straminea and B. obstructa. High levels of GTC-reactive hemagglutinin were found in all snail populations. There was no correlation between hemagglutinin titer and innate resistance of B. glabrata strains to Schistosoma mansoni. However, an increase in hemagglutinin titer occurs in B. glabrata M-RLc snails infected with Echinostoma lindoense and in snails sensitized and reexposed to this parasite.     

An Index of the Ecological Impacts of Water Toxics Emitted to Freshwater Ecosystems

We describe a composite freshwater Aquatic Toxicity Index (ATI) for chronic toxicity conditions that can be easily computed for a broad range of chemicals. The ATI expresses the potential toxic impact of chemicals on the ecosystem, scaling the potency of each chemical with respect to a reference compound (1,4 dichlorobenzene). It is based on a simple stochastic process model and a few inherent properties of each chemical, such as chronic toxicity, adsorption coefficient to sediments, and Henry's Law constant. Our goal is to provide a simple compartmental model for obtaining a rough quantitative assessment of the life-cycle environmental impact of life-cycle emissions inventory data.

To illustrate the potential of our approach we compare the ATI index, for a small set of chemicals, with comparable measures of freshwater aquatic ecotoxicity potential and freshwater sediment ecotoxicity potential obtained by others using the European-based impact assessment tool USES-LCA, which is based on a more elaborate fate and transport model. The rank correlation between the ATI and USES-LCA indices is greater than 0.85, showing surprisingly good agreement given the simple nature of our model. More analysis of the differences between ATI and the results of other models is needed, but these results suggest that our model may be useful for priority setting and meta-modeling applications.     

Cu2O纳米颗粒对小麦根系形态及遗传毒性的影响

为了阐明Cu2O纳米颗粒(NPs)暴露对植物根系的毒性效应,本研究以小麦品种'周麦18'为材料,采用水培试验方法,研究了10、50、100和200 mg·L-1浓度的Cu2O-NPs对小麦幼苗生长、根系活性、形态结构及细胞遗传学毒性的影响.结果 表明:不同浓度的Cu2O-NPs降低了小麦幼苗的根芽长度、鲜重、根活性和根...     

THE EFFECT OF CONSTANT TEMPERATURES ON THE HATCHING OF EGGS AND SURVIVAL OF THE FRESHWATER SNAIL BIOMPHALARIA GLABRATA (SAY)

SUMMARY

The incubation period and percentage hatching of eggs of pigmented and unpigmented Biomphalaria glabrata at constant temperatures were investigated in the range 14 °C to 34 °C. In order to determine the influence of extreme temperatures on adult snails, specimens of the same species were exposed to 0 °C and 40 °C for selected time periods. The results indicate that sustained temperatures below 16 °C and above 32 °C are detrimental to the development and hatching of B. glabrata embryos. The optimum temperatures for incubation period and hatching differ from each other. As far as temperature is concerned, this foreign snail species should be capable of successfully colonizing the warmer parts of southern Africa.     

Genetic characterisation of the intermediate hosts of schistosomiasis in its southern distribution limit in South America

ABSTRACT

Schistosomiasis is a tropical disease caused by the digenean parasite Schistosoma mansoni. In South America it is transmitted to humans via freshwater snails of the genus Biomphalaria. In a global warming scenario, disease range expansions to subtropical countries are possible. For the first time, the distributions and genetic identification of Biomphalaria specimens in border regions of Uruguay are reported. The inclusion of Uruguayan samples allows a better understanding of the relationships between and within taxa of Biomphalaria. Samples were collected between 2015 and 2016 using hand nets. Initially, they were classified morphologically. They were then classified genetically by analysing a fragment of the cytochrome c oxidase subunit I gene. Phylogenetic analysis revealed the presence of B. peregrina and B. occidentalis. Species belonging to the B. tenagophila complex were also recognised. Individuals initially identified from their external morphology as B. tenagophila tenagophila showed inconsistencies with the analysis of COI sequences that assigned them to B. occidentalis. Since the presence of schistosomiasis in Uruguay is likely to occur in the next few years, an exhaustive population survey of Biomphalaria taxa should be urgently developed to identify the presence of S. mansoni and the places most susceptible to be colonised by these snails.     

Comparison between three different LCIA methods for aquatic ecotoxicity and a product environmental risk assessment

Background and Objective  In the OMNIITOX project 11 partners have the common objective to improve environmental management tools for the assessment of (eco)toxicological impacts. The detergent case study aims at: i) comparing three Procter &c Gamble laundry detergent forms (Regular Powder-RP, Compact Powder-CP and Compact Liquid-CL) regarding their potential impacts on aquatic ecotoxicity, ii) providing insights into the differences between various Life Cycle Impact Assessment (LCIA) methods with respect to data needs and results and iii) comparing the results from Life Cycle Assessment (LCA) with results from an Environmental Risk Assessment (ERA). Material and Methods  The LCIA has been conducted with EDIP97 (chronic aquatic ecotoxicity) [1], USES-LCA (freshwater and marine water aquatic ecotoxicity, sometimes referred to as CML2001) [2, 3] and IMPACT 2002 (covering freshwater aquatic ecotoxicity) [4]. The comparative product ERA is based on the EU Ecolabel approach for detergents [5] and EUSES [6], which is based on the Technical Guidance Document (TGD) of the EU on Environmental Risk Assessment (ERA) of chemicals [7]. Apart from the Eco-label approach, all calculations are based on the same set of physico-chemical and toxicological effect data to enable a better comparison of the methodological differences. For the same reason, the system boundaries were kept the same in all cases, focusing on emissions into water at the disposal stage. Results and Discussion  Significant differences between the LCIA methods with respect to data needs and results were identified. Most LCIA methods for freshwater ecotoxicity and the ERA see the compact and regular powders as similar, followed by compact liquid. IMPACT 2002 (for freshwater) suggests the liquid is equally as good as the compact powder, while the regular powder comes out worse by a factor of 2. USES-LCA for marine water shows a very different picture seeing the compact liquid as the clear winner over the powders, with the regular powder the least favourable option. Even the LCIA methods which result in die same product ranking, e.g. EDIP97 chronic aquatic ecotoxicity and USES-LCA freshwater ecotoxicity, significantly differ in terms of most contributing substances. Whereas, according to IMPACT 2002 and USES-LCA marine water, results are entirely dominated by inorganic substances, the other LCIA methods and the ERA assign a key role to surfactants. Deviating results are mainly due to differences in the fate and exposure modelling and, to a lesser extent, to differences in the toxicological effect calculations. Only IMPACT 2002 calculates the effects based on a mean value approach, whereas all other LCIA methods and the ERA tend to prefer a PNEC-based approach. In a comparative context like LCA the OMNIITOX project has taken the decision for a combined mean and PNEC-based approach, as it better represents the ‘average’ toxicity while still taking into account more sensitive species. However, the main reason for deviating results remains in the calculation of the residence time of emissions in the water compartments. Conclusion and Outlook  The situation that different LCIA methods result in different answers to the question concerning which detergent type is to be preferred regarding the impact category aquatic ecotoxicity is not satisfactory, unless explicit reasons for the differences are identifiable. This can hamper practical decision support, as LCA practitioners usually will not be in a position to choose the ’right’ LCIA method for their specific case. This puts a challenge to the entire OMNIITOX project to develop a method, which finds common ground regarding fate, exposure and effect modelling to overcome the current situa-tion of diverging results and to reflect most realistic conditions.     

Development of 10 microsatellite loci in the pulmonate snail Biomphalaria kuhniana (Mollusca, Gastropoda)

We characterized 10 variable microsatellite loci in the freshwater snail Biomphalaria kuhniana, as well as conditions for multiplexing and co-loading sets of loci. Two to five alleles were detected per locus over the two studied populations in Venezuela. High inbreeding coefficients suggest high selfing rates. Cross-species amplification provided some variability at eight and three loci in the other species belonging to the Biomphalaria straminea complex (B. straminea and B. intermedia), but was unsuccessful in more divergent species.     

Studies on the interspecific competition between Helisoma duryi (wetherby) and Biomphalaria camerunensis (boettger). Size-weight relationships and laboratory competition experiments

Biological control of the intermediate hosts of schistosomiasis by means of the introduction of a competitor snail Helisoma duryi has been suggested. In the present laboratory studies the allometric size-weight relationships of H. duryi and Biomphalaria camerunensis were investigated in order to get a tool for estimating the biomass and dry-weight of snails.Competition experiments were conducted and the results showed a marked inhibition of growth and reproduction of B. camerunensis. No conclusions about the competitive interactions were drawn from the present results but experiments are established to elucidate these mechanisms.     

Bioremediation by Composting of Heavy Oil Refinery Sludge in Semiarid Conditions

The present work attempts to ascertain the efficacy of low cost technology (in our case, composting) as a bioremediation technique for reducing the hydrocarbon content of oil refinery sludge with a large total hydrocarbon content (250–300 g kg⁻¹), in semiarid conditions. The oil sludge was produced in a refinery sited in SE Spain The composting system designed, which involved open air piles turned periodically over a period of 3 months, proved to be inexpensive and reliable. The influence on hydrocarbon biodegradation of adding a bulking agent (wood shavings) and inoculation of the composting piles with pig slurry (a liquid organic fertiliser which adds nutrients and microbial biomass to the pile) was also studied. The most difficult part during the composting process was maintaining a suitable level of humidity in the piles. The most effective treatment was the one in which the bulking agent was added, where the initial hydrocarbon content was reduced by 60% in 3 months, compared with the 32% reduction achieved without the bulking agent. The introduction of the organic fertiliser did not significantly improve the degree of hydrocarbon degradation (56% hydrocarbon degraded). The composting process undoubtedly led to the biodegradation of toxic compounds, as was demonstrated by ecotoxicity tests using luminescent bacteria and tests on plants in Petri dishes.     

A Theoretical Model for Utilizing Mammalian Pharmacology and Safety Data to Prioritize Potential Impacts of Human Pharmaceuticals to Fish

Due to the potential for long-term, low-level exposure of environmental species to pharmaceuticals in the environment, concerns over chronic ecotoxicity have been raised. Pharmaceuticals typically have specific enzyme and receptor-based modes of action, which are extensively studied in mammals during drug development. A survey of the literature demonstrated that there is conservation of many enzyme/receptor systems between mammalian and teleost systems. Based on this conservation of enzyme/receptor systems across teleost species, a model has been developed to utilize the information from mammalian pharmacology and toxicology studies to evaluate the potential for chronic receptor mediated responses in fish. In this model, a measured human therapeutic plasma concentration (H_TPC) is compared to a predicted steady state plasma concentration (F_SSPC) in fish, and an effect ratio (ER = H_TPC/F_SSPC) is computed. The lower the ER, the greater the potential for a pharmacological response in fish. Data collection and model validation will strengthen the applicability of this approach as a viable tool for prioritizing research initiatives that examine the potential impact of pharmaceuticals on fish.