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Yossi Tsfadia - One of the best experts on this subject based on the ideXlab platform.
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On the molecular mass of Lumbricus erythrocruorin
Micron (Oxford England : 1993), 2004Co-Authors: Ezra Daniel, Ariel Lustig, Melvyn M. David, Yossi TsfadiaAbstract:A critical examination of the published molecular mass of erythrocruorin (Ec) from Lumbricus and related earthworm species reveals that the results do cluster, not at one, but at two values of the molecular mass. One cluster corresponds to approximately 3.6 MDa as predicted from the Vinogradov model for the hexagonal bilayer (HBL) assembly of Lumbricus terrestris EC and as estimated from the crystal structure of HBL at 5.5 A resolution. The other cluster corresponds to approximately 4.4 MDa. However, in contrast to the controversy over the molecular mass, there is a consensus that the sedimentation coefficient of intact L. terrestris Ec is approximately 60S. Drawing on the occurrence of central subunits in Ec of Oenone fulgida and few other annelid species, we propose for the 4.4 MDa molecule a model of HBL supplemented by a central mass. The proposed model abides by D6 symmetry and is a suitable candidate to represent 60S Lumbricus terrestris Ec.
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On the molecular mass of Lumbricus erythrocruorin
Micron, 2003Co-Authors: Ezra Daniel, Ariel Lustig, Melvyn M. David, Yossi TsfadiaAbstract:Abstract A critical examination of the published molecular mass of erythrocruorin (Ec) from Lumbricus and related earthworm species reveals that the results do cluster, not at one, but at two values of the molecular mass. One cluster corresponds to ∼3.6 MDa as predicted from the Vinogradov model for the hexagonal bilayer (HBL) assembly of Lumbricus terrestris EC and as estimated from the crystal structure of HBL at 5.5 A resolution. The other cluster corresponds to ∼4.4 MDa. However, in contrast to the controversy over the molecular mass, there is a consensus that the sedimentation coefficient of intact L. terrestris Ec is ∼60S. Drawing on the occurrence of central subunits in Ec of Oenone fulgida and few other annelid species, we propose for the 4.4 MDa molecule a model of HBL supplemented by a central mass. The proposed model abides by D6 symmetry and is a suitable candidate to represent 60S Lumbricus terrestris Ec.
Ezra Daniel - One of the best experts on this subject based on the ideXlab platform.
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On the molecular mass of Lumbricus erythrocruorin
Micron (Oxford England : 1993), 2004Co-Authors: Ezra Daniel, Ariel Lustig, Melvyn M. David, Yossi TsfadiaAbstract:A critical examination of the published molecular mass of erythrocruorin (Ec) from Lumbricus and related earthworm species reveals that the results do cluster, not at one, but at two values of the molecular mass. One cluster corresponds to approximately 3.6 MDa as predicted from the Vinogradov model for the hexagonal bilayer (HBL) assembly of Lumbricus terrestris EC and as estimated from the crystal structure of HBL at 5.5 A resolution. The other cluster corresponds to approximately 4.4 MDa. However, in contrast to the controversy over the molecular mass, there is a consensus that the sedimentation coefficient of intact L. terrestris Ec is approximately 60S. Drawing on the occurrence of central subunits in Ec of Oenone fulgida and few other annelid species, we propose for the 4.4 MDa molecule a model of HBL supplemented by a central mass. The proposed model abides by D6 symmetry and is a suitable candidate to represent 60S Lumbricus terrestris Ec.
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On the molecular mass of Lumbricus erythrocruorin
Micron, 2003Co-Authors: Ezra Daniel, Ariel Lustig, Melvyn M. David, Yossi TsfadiaAbstract:Abstract A critical examination of the published molecular mass of erythrocruorin (Ec) from Lumbricus and related earthworm species reveals that the results do cluster, not at one, but at two values of the molecular mass. One cluster corresponds to ∼3.6 MDa as predicted from the Vinogradov model for the hexagonal bilayer (HBL) assembly of Lumbricus terrestris EC and as estimated from the crystal structure of HBL at 5.5 A resolution. The other cluster corresponds to ∼4.4 MDa. However, in contrast to the controversy over the molecular mass, there is a consensus that the sedimentation coefficient of intact L. terrestris Ec is ∼60S. Drawing on the occurrence of central subunits in Ec of Oenone fulgida and few other annelid species, we propose for the 4.4 MDa molecule a model of HBL supplemented by a central mass. The proposed model abides by D6 symmetry and is a suitable candidate to represent 60S Lumbricus terrestris Ec.
Daniel Cluzeau - One of the best experts on this subject based on the ideXlab platform.
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Feeding behavior of epi-anecic earthworm species and their impact on soil microbial communities
2018Co-Authors: Kevin Hoeffner, Cécile Monard, Mathieu Santonja, Daniel CluzeauAbstract:Earthworms contribute to numerous ecosystem services provided by soils. Most of the studies focusing on the contributions of earthworms on leaf litter decomposition were conducted by comparing distinct ecological categories (epigeic, epi-anecic, anecic strict and endogeic), whereas their specific contributions within a given ecological category remains largely unknown. In this context, the aim of this study was to determine the contribution of four epi-anecic earthworm species (Lumbricus rubellus, Lumbricus festivus, Lumbricus centralis and Lumbricus terrestris) to the leaf litter decomposition of three plant species (Lolium perenne, Holcus lanatus and Corylus avellana) with contrasted litter traits located at both the soil surface and at a depth of 10 cm. Fungal and bacterial communities inhabiting epi-anecic earthworm burrows were also assessed using T-RFLP analysis. Epianecic earthworms improved the leaf litter mass loss solely at the soil surface, while leaf litter mass loss was mainly due to microbial activity at 10 cm deep. Leaf litter mass loss was positively correlated to the initial biomass of the epi-anecic earthworms and the intensity of this relationship was dependent on litter type. Interestingly, L. festivus seemed to have a higher contribution to surface leaf litter mass loss that was linked to a stimulation of the fungal communities in its burrows. Fungal communities were thus impacted by both the litter type and the epi-anecic earthworm identity whereas soil bacterial diversity and richness were stimulated in the earthworm burrows whatever the epi-anecic earthworm species considered. Overall, epi-anecic earthworms contributed to enhance the diversity of the drilospheric microbiota.
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Feeding behaviour of epi-anecic earthworm species and their impacts on soil microbial communities
Soil Biology and Biochemistry, 2018Co-Authors: Kevin Hoeffner, Cécile Monard, Mathieu Santonja, Daniel CluzeauAbstract:Earthworms contribute to numerous ecosystem services provided by soils. Most of the studies focusing on the contributions of earthworms on leaf litter decomposition were conducted by comparing distinct ecological categories (epigeic, epi-anecic, anecic strict and endogeic), whereas their specific contributions within a given ecological category remains largely unknown. In this context, the aim of this study was to determine the contribution of four epi-anecic earthworm species (Lumbricus rubellus, Lumbricus festivus, Lumbricus centralis and Lumbricus terrestris) to the leaf litter decomposition of three plant species (Lolium perenne, Holcus lanatus and Corylus avellana) with contrasted litter traits located at both the soil surface and at a depth of 10 cm. Fungal and bacterial communities inhabiting epi-anecic earthworm burrows were also assessed using T-RFLP analysis. Epi-anecic earthworms improved the leaf litter mass loss solely at the soil surface, while leaf litter mass loss was mainly due to microbial activity at 10 cm deep. Leaf litter mass loss was positively correlated to the initial biomass of the epi-anecic earthworms and the intensity of this relationship was dependent on litter type. Interestingly, L. festivus seemed to have a higher contribution to surface leaf litter mass loss that was linked to a stimulation of the fungal communities in its burrows. Fungal communities were thus impacted by both the litter type and the epi-anecic earthworm identity whereas soil bacterial diversity and richness were stimulated in the earthworm burrows whatever the epi-anecic earthworm species considered. Overall, epi-anecic earthworms contributed to enhance the diversity of the drilospheric microbiota. © 2018 Elsevier Ltd
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Roles of earthworm species inorganic matter recycling
2016Co-Authors: Kevin Hoeffner, Cécile Monard, Mathieu Santonja, Daniel CluzeauAbstract:Given their impact on soil functioning and their interactions with soil organisms, earthworms contribute to the recycling of organic matter and participate significantly in the numerous ecosystem services provided by soils. Most studies on the role of earthworms in organic matter recycling were conducted at the level of the four functional groups (epigeic, epi-anecic, anecic strict and endogeic), but their effects at sub-specific levels remain largely unknown. Still, within a functional group, anatomic and physiologic earthworm species traits are different, which should impact organic matter recycling. This study aims at determining, within controlled conditions, epi-anecic species differences in (i) selection, (ii) ingestion, (iii) assimilation, (iv) organic matter excretion and (v) impact on microorganisms communities implied in organic matter degradation. An experiment using microcosms was conducted to compare the impact of four species from the epi-anecic functional group (Lumbricus rubellus, Lumbricus festivus, Lumbricus centralis and Lumbricus terrestris) on the recycling of three trophic resources (Holcus lanatus, Lolium perenne and Corylus avellana). Measured parameters was taken at several places in the microcosms after 0, 10 and 20 days. Microorganisms communities were analysed using TRFLP in each earthworm species burrow walls at 20 days. Results are discussed taking into account physical and chemical properties of these 3 trophic resources (e.g. C/N ratio, phenolic compounds, percentage of lignin and cellulose...).
Rhoda Elison Hirsch - One of the best experts on this subject based on the ideXlab platform.
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Absence of ligand binding-induced tertiary changes in the multimeric earthworm Lumbricus terrestris hemoglobin. A resonance Raman study.
The Journal of biological chemistry, 1993Co-Authors: Gediminas J. A. Vidugiris, J. P. Harrington, Joel M. Friedman, Rhoda Elison HirschAbstract:In vertebrate hemoglobins, changes in protein tertiary structure induced by either ligand binding or changes in quaternary state are manifested at the heme as reflected in resonance Raman spectral changes involving the iron-proximal histidine stretching mode. No such changes are observed for Lumbricus terrestris hemoglobin. The iron-histidine stretching mode and the porphyrin breathing motion in the deoxy-, oxy-, or CO-photodissociated forms of Lumbricus hemoglobin and human hemoglobin A (pH 7.0 and 9.2, the latter to effect Lumbricus hemoglobin subunit dissociation) were studied using pulsed (10 ns) light at 435 nm. In contrast to that observed for hemoglobin A, a comparison of the spectra of the deoxy and photoproduct forms of Lumbricus hemoglobin reveal minimal differences in the region of the iron-histidine and the pi electron distribution in the heme moiety. The spectral frequencies are similar to that observed in R-state vertebrate hemoglobins. Such average behavior of the approximately 192 hemes present in Lumbricus hemoglobin is more analogous to the Raman spectral properties observed in myoglobin.
John P. Harrington - One of the best experts on this subject based on the ideXlab platform.
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Determination of the formal reduction potential of Lumbricus terrestris hemoglobin using thin layer spectroelectrochemistry.
Journal of inorganic biochemistry, 2004Co-Authors: Scott C. Dorman, John P. Harrington, Melinda S. Martin, Timothy V. JohnsonAbstract:Abstract The formal reduction potential (E°′) of Lumbricus terrestris hemoglobin was determined using thin layer spectroelectrochemistry as 0.073 (±0.005) V vs Ag/AgCl (0.281 V vs SHE, standard hydrogen electrode). Nernst plots of Lumbricus terrestris hemoglobin with tris-bipyridinecobalt(II) as a mediator titrant have similar linear slopes as Nernst plots of horse heart myoglobin with hexaamineruthenium(II) as a mediator titrant.
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Multimeric Lumbricus hemoglobin stabilization by alkali and alkaline earth cations
Comparative Biochemistry and Physiology Part A: Physiology, 1994Co-Authors: John P. HarringtonAbstract:Abstract The role of monovalent and divalent cations on the structure-function relationships operative in the large extracellular hemoglobin, isolated from the earthworm, Lumbricus terrestris , has been investigated. This study includes the effects of these cations on the rates of autoxidation, resistance to thermal unfolding, and the conversion of the methemoglobin form to the hemichrome state. At pH 7.0, the divalent cations, Mg(II), Ca(II), Sr(II), and Ba(II), were found to be more effective in reducing the rate of Lumbricus hemoglobin autoxidation than any of the monovalent cations studied. The order of effectiveness in decreasing the rate of autoxidation was Ba(II) = Ca(II) > Sr(II) > Mg(II). Resistance to thermal unfolding (25–60°C) for Lumbricus hemoglobin is increased in the presence of Ca(II) or Ba(II) ions. All of the monovalent cations appear to enhance thermal unfolding above 55°C. Reduced hemichrome formation is evident in the presence of Ca(II) or Ba(II) ions. Increased effectiveness of several of the divalent cations in reducing autoxidation, increasing resistance to thermal unfolding, and stabilization of the methemoglobin state is consistent with other investigations showing these cations prevent subunit dissociation of the Lumbricus hemoglobin molecule.
