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Robert R Jacobs - One of the best experts on this subject based on the ideXlab platform.
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observation of a partially opened triple helix conformation in 1 3 β glucan by fluorescence resonance energy transfer spectroscopy
Journal of Biological Chemistry, 2000Co-Authors: Shihhoung Young, Wenji Dong, Robert R JacobsAbstract:Abstract This study used fluorescence resonance energy transfer (FRET) spectroscopy as an indirect method to investigate the effect of NaOH treatment on the conformation of a triple-helix (1→3)-β-d-glucan and then evaluated the effect of conformation on biological activity. Previous studies have suggested that treatment of the triple-helix glucans with NaOH produces single-helix conformers. FRET spectra of the triple-helix glucan, laminarin, doubly labeled with 1-aminopyrene as donor probe and fluorescein-5-isothiocyanate as acceptor probe attached at the reducing end, showed that a partially opened triple-helix conformer was formed on treatment with NaOH. Increasing degrees of strand opening was associated with increasing concentrations of NaOH. Based on these observations we propose that a partially opened triple-helix rather than a single helix, is formed by treating the triple-helix glucans with NaOH. After neutralizing the NaOH, changes in FRET indicated that the partially opened conformer gradually reverts to the triple-helix over 8 days. Laminarian was stabilized at different degrees of partial opening and its biological activity examined using theLimulus Amebocyte lysate assay and nitric oxide production by alveolar macrophage. Both Limulus Amebocyte lysate activity and nitric oxide production were related to the degree of opening of the triple-helix. Partially open conformers were more biologically active than the intact triple-helix.
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observation of a partially opened triple helix conformation in 1 3 β glucan by fluorescence resonance energy transfer spectroscopy
Journal of Biological Chemistry, 2000Co-Authors: Shihhoung Young, Wenji Dong, Robert R JacobsAbstract:This study used fluorescence resonance energy transfer (FRET) spectroscopy as an indirect method to investigate the effect of NaOH treatment on the conformation of a triple-helix (1-->3)-beta-D-glucan and then evaluated the effect of conformation on biological activity. Previous studies have suggested that treatment of the triple-helix glucans with NaOH produces single-helix conformers. FRET spectra of the triple-helix glucan, laminarin, doubly labeled with 1-aminopyrene as donor probe and fluorescein-5-isothiocyanate as acceptor probe attached at the reducing end, showed that a partially opened triple-helix conformer was formed on treatment with NaOH. Increasing degrees of strand opening was associated with increasing concentrations of NaOH. Based on these observations we propose that a partially opened triple-helix rather than a single helix, is formed by treating the triple-helix glucans with NaOH. After neutralizing the NaOH, changes in FRET indicated that the partially opened conformer gradually reverts to the triple-helix over 8 days. Laminarian was stabilized at different degrees of partial opening and its biological activity examined using the Limulus Amebocyte lysate assay and nitric oxide production by alveolar macrophage. Both Limulus Amebocyte lysate activity and nitric oxide production were related to the degree of opening of the triple-helix. Partially open conformers were more biologically active than the intact triple-helix.
Shihhoung Young - One of the best experts on this subject based on the ideXlab platform.
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observation of a partially opened triple helix conformation in 1 3 β glucan by fluorescence resonance energy transfer spectroscopy
Journal of Biological Chemistry, 2000Co-Authors: Shihhoung Young, Wenji Dong, Robert R JacobsAbstract:Abstract This study used fluorescence resonance energy transfer (FRET) spectroscopy as an indirect method to investigate the effect of NaOH treatment on the conformation of a triple-helix (1→3)-β-d-glucan and then evaluated the effect of conformation on biological activity. Previous studies have suggested that treatment of the triple-helix glucans with NaOH produces single-helix conformers. FRET spectra of the triple-helix glucan, laminarin, doubly labeled with 1-aminopyrene as donor probe and fluorescein-5-isothiocyanate as acceptor probe attached at the reducing end, showed that a partially opened triple-helix conformer was formed on treatment with NaOH. Increasing degrees of strand opening was associated with increasing concentrations of NaOH. Based on these observations we propose that a partially opened triple-helix rather than a single helix, is formed by treating the triple-helix glucans with NaOH. After neutralizing the NaOH, changes in FRET indicated that the partially opened conformer gradually reverts to the triple-helix over 8 days. Laminarian was stabilized at different degrees of partial opening and its biological activity examined using theLimulus Amebocyte lysate assay and nitric oxide production by alveolar macrophage. Both Limulus Amebocyte lysate activity and nitric oxide production were related to the degree of opening of the triple-helix. Partially open conformers were more biologically active than the intact triple-helix.
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observation of a partially opened triple helix conformation in 1 3 β glucan by fluorescence resonance energy transfer spectroscopy
Journal of Biological Chemistry, 2000Co-Authors: Shihhoung Young, Wenji Dong, Robert R JacobsAbstract:This study used fluorescence resonance energy transfer (FRET) spectroscopy as an indirect method to investigate the effect of NaOH treatment on the conformation of a triple-helix (1-->3)-beta-D-glucan and then evaluated the effect of conformation on biological activity. Previous studies have suggested that treatment of the triple-helix glucans with NaOH produces single-helix conformers. FRET spectra of the triple-helix glucan, laminarin, doubly labeled with 1-aminopyrene as donor probe and fluorescein-5-isothiocyanate as acceptor probe attached at the reducing end, showed that a partially opened triple-helix conformer was formed on treatment with NaOH. Increasing degrees of strand opening was associated with increasing concentrations of NaOH. Based on these observations we propose that a partially opened triple-helix rather than a single helix, is formed by treating the triple-helix glucans with NaOH. After neutralizing the NaOH, changes in FRET indicated that the partially opened conformer gradually reverts to the triple-helix over 8 days. Laminarian was stabilized at different degrees of partial opening and its biological activity examined using the Limulus Amebocyte lysate assay and nitric oxide production by alveolar macrophage. Both Limulus Amebocyte lysate activity and nitric oxide production were related to the degree of opening of the triple-helix. Partially open conformers were more biologically active than the intact triple-helix.
Philippe Dubois - One of the best experts on this subject based on the ideXlab platform.
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environmental factors influencing the immune responses of the common european starfish asterias rubens
Fish & Shellfish Immunology, 2004Co-Authors: Geoffroy Coteur, N Corriere, Philippe DuboisAbstract:Abstract The influence of handling, salinity, temperature, parasitism, and gender on the immune responses (reactive oxygen species (ROS) production and coelomic amoebocyte concentration (CAC) of the starfish Asterias rubens was investigated in experimental conditions. Additionally, a year-round monthly survey in two distant sites was conducted in order to understand which of these factors most influences the immunity of A. rubens in field conditions. All considered factors, except gender and handling stress, influenced the studied immune responses of A. rubens in experimental conditions. Amoebocyte ROS production was increased at low salinity and at the lowest temperature tested (6 °C). Amoebocyte concentration in the coelomic fluid was increased in starfish infested by the ciliate Orchitophrya stellarum . However, among all these factors, only temperature could be linked with the variability in ROS production measured in the field during the monthly survey. The variability in amoebocyte concentration in the field does not seem to be linked to any of the factors considered in this study; it appears to reflect mostly an inter-individual variation rather than seasonal fluctuations. Recommended periods and indicative values of immune responses are proposed for field studies using A. rubens .
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differentiation of immune cells challenged by bacteria in the common european starfish asterias rubens echinodermata
European Journal of Cell Biology, 2002Co-Authors: Geoffroy Coteur, Genevieve Debecker, Michel Warnau, Michel Jangoux, Philippe DuboisAbstract:Amoebocytes are the main effector cells of the echinoderm immune system. In starfishes, a taxon in which bacterial diseases have been rarely reported, amoebocytes are considered to be the only circulating and immune cell type. The present paper addresses the question of amoebocyte differentiation in the starfish Asterias rubens when challenged by bacteria. Starfishes were injected with FITC-coupled bacteria (Micrococcus luteus). Amoebocytes were collected at regular time intervals for 24 h. The cytometric characteristics and the phagocytic activity were studied by flow cytometry. Three amoebocyte groups of different size were identified. The cell concentrations of the two largest and more numerous of these groups (G2 and G3) were modulated by immune stimulation while the group of smallest, less numerous, cells (G1) was unaffected. All of these cell groups were phagocytic but their kinetics of cell activation and bacteria ingestion differed. G1 cells showed the lowest phagocytic activity while G3 cells had the highest and fastest phagocytic activity. Starfish amoebocytes appear to be segregated in three groups, two of them (G2 and G3) being immunomodulated and one of them presenting a very fast reaction to bacteria. It is suggested that the high efficiency of the immune system in starfishes is related to this fast reaction.
Wenji Dong - One of the best experts on this subject based on the ideXlab platform.
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observation of a partially opened triple helix conformation in 1 3 β glucan by fluorescence resonance energy transfer spectroscopy
Journal of Biological Chemistry, 2000Co-Authors: Shihhoung Young, Wenji Dong, Robert R JacobsAbstract:Abstract This study used fluorescence resonance energy transfer (FRET) spectroscopy as an indirect method to investigate the effect of NaOH treatment on the conformation of a triple-helix (1→3)-β-d-glucan and then evaluated the effect of conformation on biological activity. Previous studies have suggested that treatment of the triple-helix glucans with NaOH produces single-helix conformers. FRET spectra of the triple-helix glucan, laminarin, doubly labeled with 1-aminopyrene as donor probe and fluorescein-5-isothiocyanate as acceptor probe attached at the reducing end, showed that a partially opened triple-helix conformer was formed on treatment with NaOH. Increasing degrees of strand opening was associated with increasing concentrations of NaOH. Based on these observations we propose that a partially opened triple-helix rather than a single helix, is formed by treating the triple-helix glucans with NaOH. After neutralizing the NaOH, changes in FRET indicated that the partially opened conformer gradually reverts to the triple-helix over 8 days. Laminarian was stabilized at different degrees of partial opening and its biological activity examined using theLimulus Amebocyte lysate assay and nitric oxide production by alveolar macrophage. Both Limulus Amebocyte lysate activity and nitric oxide production were related to the degree of opening of the triple-helix. Partially open conformers were more biologically active than the intact triple-helix.
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observation of a partially opened triple helix conformation in 1 3 β glucan by fluorescence resonance energy transfer spectroscopy
Journal of Biological Chemistry, 2000Co-Authors: Shihhoung Young, Wenji Dong, Robert R JacobsAbstract:This study used fluorescence resonance energy transfer (FRET) spectroscopy as an indirect method to investigate the effect of NaOH treatment on the conformation of a triple-helix (1-->3)-beta-D-glucan and then evaluated the effect of conformation on biological activity. Previous studies have suggested that treatment of the triple-helix glucans with NaOH produces single-helix conformers. FRET spectra of the triple-helix glucan, laminarin, doubly labeled with 1-aminopyrene as donor probe and fluorescein-5-isothiocyanate as acceptor probe attached at the reducing end, showed that a partially opened triple-helix conformer was formed on treatment with NaOH. Increasing degrees of strand opening was associated with increasing concentrations of NaOH. Based on these observations we propose that a partially opened triple-helix rather than a single helix, is formed by treating the triple-helix glucans with NaOH. After neutralizing the NaOH, changes in FRET indicated that the partially opened conformer gradually reverts to the triple-helix over 8 days. Laminarian was stabilized at different degrees of partial opening and its biological activity examined using the Limulus Amebocyte lysate assay and nitric oxide production by alveolar macrophage. Both Limulus Amebocyte lysate activity and nitric oxide production were related to the degree of opening of the triple-helix. Partially open conformers were more biologically active than the intact triple-helix.
Jacqueline Nairn - One of the best experts on this subject based on the ideXlab platform.
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Phagocytic activity of Limulus polyphemus Amebocytes in vitro
Journal of invertebrate pathology, 2012Co-Authors: Christopher J Coates, Tim Whalley, Jacqueline NairnAbstract:Phagocytosis of invading microorganisms is a fundamental component of innate immunity. The Atlantic horseshoe crab, Limulus polyphemus, possesses a single immune cell type, the granular Amebocyte. Amebocytes release a repertoire of potent immune effectors in the presence of pathogens, and function in hemostasis. In contrast to other arthropod immunocytes, the properties of Amebocyte phagocytosis remain poorly characterised, restricted by the technical challenges associated with handling these labile cells. We have addressed these challenges and observed the internalisation of microbial and synthetic targets by Amebocytes in vitro. Confirmation of target internalisation was achieved using a combination of fluorescent quenching and lipophilic membrane probes: R18 and FM 1-43. Viability, morphological integrity and functionality of extracted Amebocytes appeared to be retained in vitro. The phagocytic properties of L. polyphemus Amebocytes described here, in the absence of endotoxin, are similar to those observed for arthropod immunocytes and mammalian neutrophils.
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effect of temperature on biochemical and cellular properties of captive limulus polyphemus
Aquaculture, 2012Co-Authors: Christopher J Coates, Emma L Bradford, Carsten Krome, Jacqueline NairnAbstract:Abstract The maintenance of horseshoe crabs in culture is being explored to address the recent decline of the species. While a number of indicators have been used to monitor the health status of the horseshoe crabs, the limited success of culture methods suggests that an alternative approach is required. In this study, we have monitored the effect of temperature on a unique combination of physiological, biochemical and cellular characteristics to assess the health status of the Atlantic horseshoe crab, Limulus polyphemus . L. polyphemus was maintained across the temperature range, 8 °C to 23 °C, for a period of 56 days. Mean body weight, hemocyanin concentration and function, Amebocyte density and morphology were monitored. Results showed a general decrease in hemocyanin concentration and Amebocyte density across the temperature range. The percentage of hemocyanin with bound dioxygen and the specific activity of phenoloxidase, derived from hemocyanin, changed little during the experiment. The decreased Amebocyte density was accompanied by a shift in Amebocyte morphology with increasing temperature. In this study, the immune-competence of horseshoe crabs appears to be adversely affected by captivity induced stress and this is exacerbated by higher temperatures.