Incorporation of lead into calcium carbonate granules secreted by earthworms living in lead contaminated soils

The influence of soil organisms on metal mobility and bioavailability in soils is not currently fully understood. We conducted experiments to determine whether calcium carbonate granules secreted by the earthworm Lumbricus terrestris could incorporate and immobilise lead in lead- and calcium- amended artificial soils. Soil lead concentrations were up to 2000 mg kg-1 and lead:calcium ratios by mass were 0.5-8. Average granule production rates of 0.39 + 0.04 mgcalcite earthworm-1 day-1 did not vary with soil lead concentration. The lead:calcium ratio in granules increased significantly with that of the soil (r2 = 0.81, p = 0.015) with lead concentrations in granules reaching 1577 mg kg-1. X-ray diffraction detected calcite and aragonite in the granules with indications that lead was incorporated into the calcite at the surface of the granules. In addition to the presence of calcite and aragonite X-ray absorption spectroscopy indicated that lead was present in the granules mainly as complexes sorbed to the surface but with traces of lead-bearing calcite and cerussite. The impact that lead-incorporation into earthworm calcite granules has on lead mobility at lead-contaminated sites will depend on the fraction of total soil lead that would be otherwise mobile.

Belowground interactive effects of elevated CO2, plant diversity and earthworms in grassland microcosms

The potential interactive effects of future atmospheric CO2 concentrations and plant diversity loss on the functioning of belowground systems are still poorly understood. Using a microcosm greenhouse approach with assembled grassland plant communities of different diversity (1, 4 and 8 species), we explored the interactive effects between plant species richness and elevated CO2 (ambient and + 200 p.p.m.v. CO2) on earthworms and microbial biomass. We hypothesised that the beneficial effect of increasing plant species richness on earthworm performance and microbial biomass will be modified by elevated CO2 through impacts on belowground organic matter inputs, soil water availability and nitrogen availability. We found higher earthworm biomass in eight species mixtures under elevated CO2, and higher microbial biomass under elevated CO2 in four and eight species mixtures if earthworms were present. The results suggest that plant driven changes in belowground organic matter inputs, soil water availability and nitrogen availability explain the interactive effects of CO2 and plant diversity on the belowground compartment. The interacting mechanisms by which elevated CO2 modified the impact of plant diversity on earthworms and microorganisms are discussed.

Soil food web properties explain ecosystem services across European land use systems

Intensive land use reduces the diversity and abundance of many soil biota, with consequences for the processes that they govern and the ecosystem services that these processes underpin. Relationships between soil biota and ecosystem processes have mostly been found in laboratory experiments and rarely are found in the field. Here, we quantified, across four countries of contrasting climatic and soil conditions in Europe, how differences in soil food web composition resulting from land use systems (intensive wheat rotation, extensive rotation, and permanent grassland) influence the functioning of soils and the ecosystem services that they deliver. Intensive wheat rotation consistently reduced the biomass of all components of the soil food web across all countries. Soil food web properties strongly and consistently predicted processes of C and N cycling across land use systems and geographic locations, and they were a better predictor of these processes than land use. Processes of carbon loss increased with soil food web properties that correlated with soil C content, such as earthworm biomass and fungal/bacterial energy channel ratio, and were greatest in permanent grassland. In contrast, processes of N cycling were explained by soil food web properties independent of land use, such as arbuscular mycorrhizal fungi and bacterial channel biomass. Our quantification of the contribution of soil organisms to processes of C and N cycling across land use systems and geographic locations shows that soil biota need to be included in C and N cycling models and highlights the need to map and conserve soil biodiversity across the world.

Biomineralisation by earthworms: an investigation into the stability and distribution of amorphous calcium carbonate

Background Many biominerals form from amorphous calcium carbonate (ACC), but this phase is highly unstable when synthesised in its pure form inorganically. Several species of earthworm secrete calcium carbonate granules which contain highly stable ACC. We analysed the milky fluid from which granules form and solid granules for amino acid (by liquid chromatography) and functional group (by Fourier transform infrared (FTIR) spectroscopy) compositions. Granule elemental composition was determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES) and electron microprobe analysis (EMPA). Mass of ACC present in solid granules was quantified using FTIR and compared to granule elemental and amino acid compositions. Bulk analysis of granules was of powdered bulk material. Spatially resolved analysis was of thin sections of granules using synchrotron-based μ-FTIR and EMPA electron microprobe analysis. Results The milky fluid from which granules form is amino acid-rich (≤ 136 ± 3 nmol mg−1 (n = 3; ± std dev) per individual amino acid); the CaCO3 phase present is ACC. Even four years after production, granules contain ACC. No correlation exists between mass of ACC present and granule elemental composition. Granule amino acid concentrations correlate well with ACC content (r ≥ 0.7, p ≤ 0.05) consistent with a role for amino acids (or the proteins they make up) in ACC stabilisation. Intra-granule variation in ACC (RSD = 16%) and amino acid concentration (RSD = 22–35%) was high for granules produced by the same earthworm. Maps of ACC distribution produced using synchrotron-based μ-FTIR mapping of granule thin sections and the relative intensity of the ν2: ν4 peak ratio, cluster analysis and component regression using ACC and calcite standards showed similar spatial distributions of likely ACC-rich and calcite-rich areas. We could not identify organic peaks in the μ-FTIR spectra and thus could not determine whether ACC-rich domains also had relatively high amino acid concentrations. No correlation exists between ACC distribution and elemental concentrations determined by EMPA. Conclusions ACC present in earthworm CaCO3 granules is highly stable. Our results suggest a role for amino acids (or proteins) in this stability. We see no evidence for stabilisation of ACC by incorporation of inorganic components.

Calibration and evaluation of individual-based models using Approximate Bayesian Computation

This paper investigates the feasibility of using approximate Bayesian computation (ABC) to calibrate and evaluate complex individual-based models (IBMs). As ABC evolves, various versions are emerging, but here we only explore the most accessible version, rejection-ABC. Rejection-ABC involves running models a large number of times, with parameters drawn randomly from their prior distributions, and then retaining the simulations closest to the observations. Although well-established in some fields, whether ABC will work with ecological IBMs is still uncertain. Rejection-ABC was applied to an existing 14-parameter earthworm energy budget IBM for which the available data consist of body mass growth and cocoon production in four experiments. ABC was able to narrow the posterior distributions of seven parameters, estimating credible intervals for each. ABC’s accepted values produced slightly better fits than literature values do. The accuracy of the analysis was assessed using cross-validation and coverage, currently the best available tests. Of the seven unnarrowed parameters, ABC revealed that three were correlated with other parameters, while the remaining four were found to be not estimable given the data available. It is often desirable to compare models to see whether all component modules are necessary. Here we used ABC model selection to compare the full model with a simplified version which removed the earthworm’s movement and much of the energy budget. We are able to show that inclusion of the energy budget is necessary for a good fit to the data. We show how our methodology can inform future modelling cycles, and briefly discuss how more advanced versions of ABC may be applicable to IBMs. We conclude that ABC has the potential to represent uncertainty in model structure, parameters and predictions, and to embed the often complex process of optimizing an IBM’s structure and parameters within an established statistical framework, thereby making the process more transparent and objective.

Molecular masses and sedimentation coefficients of extracellular hemoglobin of Glossoscolex paulistus: Alkaline oligomeric dissociation

The giant extracellular hemoglobin of Glossoscolex paulistus (HbGp) has a molecular mass (M) of 3600 +/- 100 kDa and a standard sedimentation coefficient (s(20.w)(0)) of 58 S. estimated by analytical ultracentrifugation (AUC). In the present work, further AUC studies were developed for HbGp, at pH 10.0, which favors oligomeric dissociation into lower M species. The HbGp oligomer is formed by globin chains a, b, c and d plus the linker chains. The pure monomeric fraction, subunit d, and HbGp at pH 10.0, in the presence of beta-mercaptoethanol, were also studied. Our results indicate that for samples of pure subunit d, besides the monomeric species with s(20.w)(0) of 2.0 S, formation of dimer of subunit d is observed with s(20.w)(0) of around 2.9 S. For the whole HbGp at pH 10.0 contributions from monomers, trimers and linkers are observed. No contribution from 58 S species was observed for the sample of oxy-HbGp at pH 10.0, showing its complete dissociation. For cyanomet-HbGp form a contribution of 17% is observed for the un-dissociated oligomer, consistent with data from other techniques that show the cyanomet-form is more stable as compared to oxy-HbGp. Masses of HbGp subunits, especially trimer abc and monomeric chains a, b, c and d, were also estimated from sedimentation equilibrium data, and are in agreement with the results from MALDI-TOF-MS. (C) 2010 Elsevier B.V. All rights reserved.

On the molecular mass of the extracellular hemoglobin of Glossoscolex paulistus: Analytical ultracentrifugation reexamination

The giant extracellular hemoglobin of Glossoscolex paulistus (HbGp) is constituted by Subunits containing heme groups with molecular masses (M) in the range of 15 to 19 kDa, monomers of 16 kDa (d), and trimers of 51 to 52 kDa (abc) linked by nonheme structures named linkers of 24 to 32 kDa (L). HbGp is homologous to Lumbricus terrestris hemoglobin (HbLt). Several reports propose M of HbLt in the range of 3.6 to 4.4 MDa. Based on subunits M determined by mass spectrometry and assuming HbGp stoichiometry of 12(abcd)(3)L(3) (Vinogradov model) plus 144 heme groups, a Value of M for HbGp oligomer of 3560 kDa can be predicted. This Value is nearly 500 kDa higher than the unique HbGp M Value reported in the literature. In the current work, sedimentation velocity analytical ultracentrifugation (AUC) experiments were performed to obtain M for HbGp in oxy and cyano-met forms. s(20,w)(0), values of 58.1 +/- 0.2 S and 59.6 +/- 0.2 S, respectively, for the two oxidation forms were obtained. The ratio between sedimentation and diffusion coefficients supplied values for M of approximately 3600 100 and 3700 100 kDa for oxy and cyano-met HbGp forms, respectively. An independent determination of the partial specific volume, V(bar), for HbGp was performed based on density measurements, providing a value of 0.764 +/- 0.008, in excellent agreement with the estimates from SEDFIT software. Our results show total consistency between M obtained by AUC and recent partial characterization by mass spectrometry. Therefore, HbGp possesses M very close to that of HbLt, suggesting an oligomeric assembly in agreement with the Vinogradov model. (c) 2008 Elsevier Inc. All rights reserved.

Germinação de sementes e otimização de técnicas de micropropagação de umbuzeiro (spondias tuberosa, arr.) anacardiaceae

The brazilian-plum (Spondias tuberosa, His) is a tropical fruit tree that has been consolidated in the market for agribusiness processing, due to its characteristic flavor of fruit. Accordingly, studies to optimize the propagation of plants are necessary for production of seedlings with agronomic and quality assurance measures. This study aimed at determining the efficient techniques for uniform seed germination, as brazilian-plum seed present mechanical dormancy, and establish optimal culture media for multiplication of shoots from the in vitro micropropagation. Firstly, in a greenhouse at the Universidade Federal do Rio Grande do Norte, was evaluated the influence of different methods of breaking dormancy in the emergence of seedlings of brazilian-plum and speed of germination (IVG) of seeds. After 60 days of cultivation, it was found that splay in the distal portion of the seed was the best treatment, with rates of 85.33% in germinability and 3.415 of IVG, compared with the treatment of seed-soaking in water for 12h + humus and the control group. Subsequently, new sources of seedling explants were obtained in studies of tissue culture. Laboratory of Plant Biotechnology that the university, was used stem apex, nodal segments and internodes in search of decontamination with various concentrations of calcium hypochlorite [Ca(OCl)2] and micropropagation, inoculating them in half WPM (1980) with various concentrations of 6-benzylaminopurine (BAP). We used 10 sample units with three replications for different concentrations of [Ca(OCl)2], BAP and explants type. After thirty days, which was observed for the control of contamination, during the establishment in vitro, concentrations of [Ca(OCl)2] between 0.5% and 2.0% were effective in combating exogenous contamination of the apex. In nodal segments and internodes, concentrations of [Ca(OCl)2] between 1.0% and 2.0% and 1.5% and 2.0% were respectively, sufficient to reduce the percentage of losses in these infestations explants. For micropropagation, the culture medium supplemented with 0.1 mg.L-1 BAP promotes better development of multiple shoots per explants from nodal segment. However, success does not get to shoot training in internodal segment

Alterações na matéria orgânica e na biomassa microbiana em solo de mata natural submetido a diferentes manejos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Propagação vegetativa da alfavaca-cravo utilizando diferentes tipos de estacas e substratos

A propagação vegetativa é considerada importante ferramenta para o melhoramento de espécies lenhosas e herbáceas e vem sendo amplamente utilizada, visando melhorar e manter variedades de importância econômica e medicinal. Neste contexto utilizou-se estacas de alfavaca-cravo de 15 cm para apicais e 25 cm para as medianas, sendo estas com e sem folhas. As estacas foram plantadas em bandejas de isopor de 72 células, utilizando-se 10 substratos. Após 35 dias, as estacas foram retiradas com cuidado, sendo as partes aéreas e radiculares separadas e acondicionadas em saco de papel e mantidas em estufa a 70ºC por 48 h para posterior avaliação da matéria seca. Analisou-se a percentagem de enraizamento, número de folhas na estaca, peso de matéria seca de folha e de raiz. Não houve interação significativa entre os diferentes tipos de substrato e estaca para percentagem de enraizamento, sendo que os substratos de modo geral diferiram pouco entre si. Entre os tipos de estaca destacaram-se para esta variável a mediana sem folha e a apical com folha. Para as demais variáveis houve interação significativa entre o tipo de estaca e o substrato. A melhor estaca foi a mediana sem folhas plantadas em substrato arisco + esterco + húmus e vermiculita nas seguintes proporções: 20%:40%:40%; 40%:20%:40% e 40%:40%.

Avaliação da influência da matéria orgânica, na determinação quantitativa de metais em amostras de sedimento, por espectrometria de absorção atômica e análise de metais traços por fluorescência de raios-X

The proposal of this work is to evaluate the influence of the organic matter on the results of the analyses of the metals (Zn, Pb, Al, Cu, Cr, Fe, Cd e Ni) for Atomic Absorption Spectrometry (AAS), so much in the extraction stage as in the reading using for that the chemometrics. They were used for this study sample of bottom sediment collected in river Jundiaí in the vicinity of the city of Macaíba-RN, commercial humus and water of the station of treatment of sewer of UFRN. Through the analyses accomplished by EAA it was verified that the interference of the organic matter happens in the extraction stage and not in the reading. With relationship to the technique of X Ray Fluorescence Spectrometry (XRFS), the present work has as intended to evaluate the viability of this technique for quantitative analysis of trace metals (Cr, Ni, Cu, Zn, Rb, Sr and Pb) in having leached obtained starting from the extraction with acqua regia for an aqueous solution. The used samples constitute the fine fraction (<0.063 mm) of sediments of swamp of the river Jundiaí. The preparation of tablets pressed starting from the dry residue of those leached it allowed your analysis in the solid form. This preliminary study shows that, in the case of the digestion chemistry partially of the fine fractions of bottom sediments used for environmental studies, the technique of applied EFRX to the analysis of dry residues starting from having leached with acqua regia, compared her it analyzes of the leached with ICP-OES, it presents relative mistakes for Cu, Pb, Sr and Zn below 10%

Biodegradation and toxicological evaluation of lubricant oils

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Screening of filamentous fungi for production of enzymes of biotechnological interest

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Recursos alimentares explorados pelos cupins (Insecta: Isoptera)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influência de substratos na formação dos porta-enxertos: limoeiro-Cravo (Citrus limonia Osbeck) e tangerineira-Cleópatra (Citrus reshni Hort. Ex Tanaka) em ambiente protegido

Visando a estudar o efeito do substrato na produção de porta-enxertos de limoeiro-Cravo e tangerineira-Cleópatra em tubetes sob ambiente protegido, conduziu-se este trabalho na Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal-UNESP. O estudo foi realizado em ambiente coberto com sombrite preto sem proteção lateral, adotando-se delineamento inteiramente casualizado, em esquema fatorial 5x2, 4 repetições e 20 sementes por parcela. Utilizaram-se os substratos húmus de minhoca oriundo de esterco de curral (H%) e vermiculita média (V%), sendo S1=H0 V100; S2=H25 V75; S3=H50 V50; S4=H75 V25 e S5=H100 V0. Avaliaram-se o número de plântulas emergidas, altura das plantas, diâmetro do caule, massas fresca e seca de raiz e parte aérea. Observaram-se resultados estatisticamente significativos para diâmetro do caule, aos 104 e 118 dias após a semeadura (DAS) entre espécies, com superioridade de Cravo em relação a Cleópatra, porém não aos 132 DAS. Não foi constatada diferença significativa entre os substratos. Quanto à massa fresca de parte aérea, nenhuma diferença estatística ocorreu entre as espécies; porém, quanto aos substratos, S3 mostrou-se superior a S1, não diferindo, entretanto, dos demais. Embora a análise estatística não tenha mostrado diferenças significativas entre os tratamentos para os outros parâmetros analisados, S3 destacou-se entre os substratos testados.