The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
Fernando García-carreño - One of the best experts on this subject based on the ideXlab platform.
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Aspartic Cathepsin D Endopeptidase Contributes to Extracellular Digestion in Clawed Lobsters Homarus americanus and Homarus gammarus
Marine Biotechnology, 2010Co-Authors: Liliana Rojo, Adriana Muhlia-almazan, Reinhard Saborowski, Fernando García-carreñoAbstract:Acid digestive proteinases were studied in the gastric fluids of two species of clawed lobster ( Homarus americanus and Homarus gammarus ). An active protein was identified in both species as aspartic proteinase by specific inhibition with pepstatin A. It was confirmed as cathepsin D by mass mapping, N-terminal, and full-length cDNA sequencing. Both lobster species transcribed two cathepsin D mRNAs: cathepsin D1 and cathepsin D2. Cathepsin D1 mRNA was detected only in the midgut gland, suggesting its function as a digestive enzyme. Cathepsin D2 mRNA was found in the midgut gland, gonads, and muscle. The deduced amino acid sequence of cathepsin D1 and cathepsin D2 possesses two catalytic DTG active-site motifs, the hallmark of aspartic proteinases. The putatively active cathepsin D1 has a molecular mass of 36.4 kDa and a calculated p I of 4.14 and possesses three potential glycosylation sites. The sequences showed highest similarities with cathepsin D from insects but also with another crustacean cathepsin D. Cathepsin D1 transcripts were quantified during a starvation period using real-time qPCR. In H. americanus , 15 days of starvation did not cause significant changes, but subsequent feeding caused a 2.5-fold increase. In H. gammarus , starvation caused a 40% reduction in cathepsin D1 mRNA, and no effect was observed with subsequent feeding.
Thomas A. Richards - One of the best experts on this subject based on the ideXlab platform.
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Discovery of novel intermediate forms redefines the fungal tree of life
Nature, 2011Co-Authors: Meredith D M Jones, Irene Forn, Catarina Gadelha, Martin J. Egan, Ramon Massana, David Bass, Thomas A. RichardsAbstract:Fungi are the principal degraders of biomass in terrestrial ecosystems and establish important interactions with plants and animals. However, our current understanding of fungal evolutionary diversity is incomplete and is based upon species amenable to growth in culture. These culturable fungi are typically yeast or filamentous forms, bound by a rigid cell wall rich in chitin. Evolution of this body plan was thought critical for the success of the Fungi, enabling them to adapt to heterogeneous habitats and live by osmotrophy: Extracellular Digestion followed by nutrient uptake. Here we investigate the ecology and cell biology of a previously undescribed and highly diverse form of eukaryotic life that branches with the Fungi, using environmental DNA analyses combined with fluorescent detection via DNA probes. This clade is present in numerous ecosystems including soil, freshwater and aquatic sediments. Phylogenetic analyses using multiple ribosomal RNA genes place this clade with Rozella, the putative primary branch of the fungal kingdom. Tyramide signal amplification coupled with group-specific fluorescence in situ hybridization reveals that the target cells are small eukaryotes of 3-5 μm in length, capable of forming a microtubule-based flagellum. Co-staining with cell wall markers demonstrates that representatives from the clade do not produce a chitin-rich cell wall during any of the life cycle stages observed and therefore do not conform to the standard fungal body plan. We name this highly diverse clade the cryptomycota in anticipation of formal classification.
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fungal tree of life
Nature: RESEARCH LETTER, 2011Co-Authors: Meredith D M Jones, Irene Forn, Catarina Gadelha, Martin J. Egan, Ramon Massana, David Bass, Thomas A. RichardsAbstract:Fungi are the principal degraders of biomass in terrestrial ecosystems and establish important interactions with plants and animals. However, our current understanding of fungal evolutionary diversity is incomplete and is based upon species amenable to growth in culture. These culturable fungi are typically yeast or filamentous forms, bound by a rigid cell wall rich in chitin. Evolution of this body plan was thought critical for the success of the Fungi, enabling them to adapt to heterogeneous habitats and live by osmotrophy: Extracellular Digestion followed by nutrient uptake. Here we investigate the ecology and cell biology of a previously undescribed and highly diverse form of eukaryotic life that branches with the Fungi, using environmental DNA analyses combined with fluorescent detection via DNA probes. This clade is present in numerous ecosystems including soil, freshwater and aquatic sediments. Phylogenetic analyses using multiple ribosomal RNA genes place this clade with Rozella, the putative primary branch of the fungal kingdom. Tyramide signal amplification coupled with group-specific fluorescence in situ hybridization reveals that the target cells are small eukaryotes of 3-5 μm in length, capable of forming a microtubule-based flagellum. Co-staining with cell wall markers demonstrates that representatives from the clade do not produce a chitin-rich cell wall during any of the life cycle stages observed and therefore do not conform to the standard fungal body plan. We name this highly diverse clade the cryptomycota in anticipation of formal classification.
Christopher D Mcquaid - One of the best experts on this subject based on the ideXlab platform.
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Extracellular Digestion in two co occurring intertidal mussels perna perna l and choromytilus meridionalis kr and the role of enteric bacteria in their digestive ecology
Journal of Experimental Marine Biology and Ecology, 1999Co-Authors: Carol A Simon, Christopher D McquaidAbstract:The style enzymes and enteric bacteria of two intertidal mussels, Perna perna (L.) and Choromytilus meridionalis (Kr), were tested for activity on ten structural and storage carbohydrates. Both mussels digested the storage carboyhydrates amylose, glycogen and laminarin, and the structural carbohydrate carboxymethyl cellulose (CMC). C. meridionalis broke down the digested storage carbohydrates with equal efficiency, while P. perna digested laminarin and glycogen more efficiently than amylose. P. perna produced large volumes of enzymes with low dissociation rates, while the opposite was true for C. meridionalis. As a result, P. perna released significantly more glucose (ANOVA: P<0.05) from all substrates, even though it had significantly lower specific enzyme activities (P<0.05). Likewise, both mussels could digest bacteria isolated from their guts, but P. perna digested more bacterial strains, more efficiently, than C. meridionalis. In contrast, C. meridionalis housed larger populations of gut bacteria which digested carbohydrates more efficiently than those from P. perna. Mixed bacterial cultures from both mussels showed consistently high activity on storage carbohydrates. Activity was consistent, but low, on two structural carbohydrates (CMC and mannan) but sporadic on the other structural compounds (carrageenin, fucoidan and xylan). Electron microscopy showed that both mussels housed two distinct populations of bacteria: resident spirochaete bacteria (presumably Cristispira spp) in the style, and a mixture of rod, coccoid and filamentous bacteria associated with the gut contents. The sporadic presence of bacteria which digest most structural carbohydrates, and their association with the gut contents, indicate that these bacteria are transient. This means that the association between the mussels and their enteric bacteria is incidental rather than obligatory. The spirochaete bacteria in the style have an obligate relationship with the mussels and may increase the amount of carbohydrases produced, but not the range of enzymes available to the host.
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Extracellular Digestion in two co-occurring intertidal mussels (Perna perna (L.) and Choromytilus meridionalis (Kr)) and the role of enteric bacteria in their digestive ecology
Journal of Experimental Marine Biology and Ecology, 1999Co-Authors: Carol A Simon, Christopher D McquaidAbstract:The style enzymes and enteric bacteria of two intertidal mussels, Perna perna (L.) and Choromytilus meridionalis (Kr), were tested for activity on ten structural and storage carbohydrates. Both mussels digested the storage carboyhydrates amylose, glycogen and laminarin, and the structural carbohydrate carboxymethyl cellulose (CMC). C. meridionalis broke down the digested storage carbohydrates with equal efficiency, while P. perna digested laminarin and glycogen more efficiently than amylose. P. perna produced large volumes of enzymes with low dissociation rates, while the opposite was true for C. meridionalis. As a result, P. perna released significantly more glucose (ANOVA: P
Gabriela Puls - One of the best experts on this subject based on the ideXlab platform.
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the ctenophore mnemiopsis leidyi has a flow through system for Digestion with three consecutive phases of Extracellular Digestion
Physiological and Biochemical Zoology, 1997Co-Authors: Dirk Bumann, Gabriela PulsAbstract:The ctenophore (comb jelly) Mnemiopsis leidyi is a periodically abundant and voracious predator in U.S. coastal waters. Mnemiopsis leidyi is especially competitive at high prey concentrations because of its very efficient Extracellular Digestion. We investigated the functional basis for these outstanding Digestion capabilities. Extracellular Digestion takes place in the pharynx and consists of three distinct and consecutive phases. The three phases take place in different regions of the pharynx so that various prey items can be treated simultaneously in each phase. The first phase is acidic, while the second and the third are alkaline. Extracellular Digestion is completed by ciliary currents that mechanically disrupt the predigested food. Bulky indigestible food fragments are expelled through the mouth. Except for a small area, the paths for ingestion and egestion are separate. Hence, both ingestion and egestion can occur simultaneously. The flattened and elongated shape of the pharynx provides the morphological basis for this flow-through system with various regions for different digestive treatments of the food. This system is highly elaborated compared with those of other lower invertebrates and allows for an efficient, fast, and simultaneous Digestion of many prey items, which accounts for the outstanding feeding capabilities of M. leidyi.
Liliana Rojo - One of the best experts on this subject based on the ideXlab platform.
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Aspartic Cathepsin D Endopeptidase Contributes to Extracellular Digestion in Clawed Lobsters Homarus americanus and Homarus gammarus
Marine Biotechnology, 2010Co-Authors: Liliana Rojo, Adriana Muhlia-almazan, Reinhard Saborowski, Fernando García-carreñoAbstract:Acid digestive proteinases were studied in the gastric fluids of two species of clawed lobster ( Homarus americanus and Homarus gammarus ). An active protein was identified in both species as aspartic proteinase by specific inhibition with pepstatin A. It was confirmed as cathepsin D by mass mapping, N-terminal, and full-length cDNA sequencing. Both lobster species transcribed two cathepsin D mRNAs: cathepsin D1 and cathepsin D2. Cathepsin D1 mRNA was detected only in the midgut gland, suggesting its function as a digestive enzyme. Cathepsin D2 mRNA was found in the midgut gland, gonads, and muscle. The deduced amino acid sequence of cathepsin D1 and cathepsin D2 possesses two catalytic DTG active-site motifs, the hallmark of aspartic proteinases. The putatively active cathepsin D1 has a molecular mass of 36.4 kDa and a calculated p I of 4.14 and possesses three potential glycosylation sites. The sequences showed highest similarities with cathepsin D from insects but also with another crustacean cathepsin D. Cathepsin D1 transcripts were quantified during a starvation period using real-time qPCR. In H. americanus , 15 days of starvation did not cause significant changes, but subsequent feeding caused a 2.5-fold increase. In H. gammarus , starvation caused a 40% reduction in cathepsin D1 mRNA, and no effect was observed with subsequent feeding.
