Search results for "Phenoloxidase"
showing 10 items of 32 documents
Variation and covariation in infectivity, virulence and immunodepression in the host-parasite association Gammarus pulex-Pomphorhynchus laevis.
2009
Parasites often manipulate host immunity for their own benefit, either by exacerbating or suppressing the immune response and this may directly affect the expression of parasite virulence. However, genetic variation in immunodepression, which is a prerequisite to its evolution, and the relationship between immunodepression and virulence, have rarely been studied. Here, we investigated the variation among sibships of the acanthocephalan parasite, Pomphorhynchus laevis , in infecting and in immunodepressing its amphipod host, Gammarus pulex . We also assessed the covariation between infectivity, parasite-induced immune depression and host mortality (parasite virulence). We found that infecti…
Temporal patterns in immune responses to a range of microbial insults (Tenebrio molitor).
2008
8 pages; International audience; Much work has elucidated the pathways and mechanisms involved in the production of insect immune effector systems. However, the temporal nature of these responses with respect to different immune insults is less well understood. This study investigated the magnitude and temporal variation in phenoloxidase and antimicrobial activity in the mealworm beetle Tenebrio molitor in response to a number of different synthetic and real immune elicitors. We found that antimicrobial activity in haemolymph increased rapidly during the first 48h after a challenge and was maintained at high levels for at least 14 days. There was no difference in the magnitude of responses …
Prophenoloxidase activating system in tunicate hemolymph
1996
The activation sequence and related factors of the prophenoloxidase activating system in crustaceans was compared with the equivalent system in tunicates. Both solitary and colonial ascidians present in their hemolymph a copper-dependent phenoloxidase activity that may be inhibited by tropolone and phenylthiourea. Carbohydrates are able, to various extents, to trigger proPO system which requires serine protease cleavage for activation to phenoloxidase (PO). In some ascidians, hemocytes called ≪morula cells≫ show PO activity, while in Ciona intestinalis the ≪univacuolar refractile granulocytes≫ are positive after cytochemical staining with L-dopa. The relationships between proPO system and d…
Tribolium castaneum Apolipophorin-III acts as an immune response protein against Bacillus thuringiensis Cry3Ba toxic activity
2013
In this study, a 2.1-fold Apolipophorin-III mRNA up-regulation was found in Tribolium castaneum larvae challenged with Bacillus thuringiensis Cry3Ba spore-crystal mixture. Knockdown of Apolipophorin-III by RNAi resulted in increased T. castaneum larvae susceptibility following Cry3Ba spore-crystal treatment, demonstrating Apolipophorin-III involvement in insect defense against B. thuringiensis. We showed that Apolipophorin-III participates in T. castaneum immune response to B. thuringiensis activating the prophenoloxidase cascade since: (i) phenoloxidase activity significantly increased after Cry3Ba spore-crystal treatment compared to untreated or Cry1Ac spore-crystal treated larvae and (ii…
How to Deal with Uninvited Guests in Wine: Copper and Copper-containing Oxidases
2020
Copper is one of the most frequently occurring heavy metals in must and wine. It is introduced by pesticides, brass fittings, and as copper sulphate for treatment of reductive off-flavors. At higher concentrations, copper has harmful effects on the wine. It contributes to the oxidation of wine ingredients, browning reactions, cloudiness, inhibition of microorganisms, and wine fermentation. Last but not least, there is also a danger to the consumer. At present, some physicochemical methods exist to reduce the copper content in must and wine, but they all have their shortcomings. A possible solution is the biosorption of metals by yeasts or lactobacilli. Copper can also reach must and wine in…
Variation in the immune state of Gammarus pulex (Crustacea, Amphipoda) according to temperature: are extreme temperatures a stress?
2017
9 pages; International audience; Temperature is known to impact host-parasite interactions in various ways. Such effects are often regarded as the consequence of the increased metabolism of parasites with increasing temperature. However, the effect of temperature on hosts' immune system could also be a determinant. Here we assessed the influence of temperature on the immunocompetence of the crustacean amphipod Gammarus pulex. Amphipods play a key ecological role in freshwater ecosystems that can be altered by several parasites. We investigated the consequences of three weeks of acclimatization at four temperatures (from 9 °C to 17 °C) on different immunological parameters. Temperature influ…
The Expression of an Immune-Related Phenoloxidase Gene is Modulated in Ciona Intestinalis Ovary, Test Cells, Embryos and Larva
2015
Two distinct Ciona intestinalis phenoloxidases (CinPO1, 2) had previously been cloned and sequenced. The CinPO2 is involved in innate immunity and is expressed by inflammatory hemocytes that populate the tunic and pharynx vessels as a response to LPS inoculation. In situ hybridization and immunohistochemistry assays on histological section, showed that the expression of this gene and the produced protein are shared with oogenesis, embryogenesis and larval morphogenesis. Intriguingly, upregulation of gene transcription was found in the test cell layer that envelopes the ovary follicle, ovulated egg, and gastrula, as well as it was modulated in the zygotic nucleus of outer balstomers of 32-ce…
Phenoloxidase-dependent cytotoxic mechanism in ascidian (Styela plicata) hemocytes active against erythrocytes and K562 tumor cells.
1997
The cytotoxic activity against rabbit erythrocytes (RE) and human K562 tumor cells by Styela plicata hemocytes was significantly related to the phenoloxidase (PO) which converts phenols to quinone and initiates the melanogenic pathway. The effector hemocyte population, separated in a Percoll density gradient band, enriched in a granulocyte type named "morula cells", was examined with RE in a hemocyte cytotoxic assay and plaque forming cell assay. Inhibition experiments with the copper chelating agents 1-phenyl-2-thiourea and tropolone, the substrate analogue sodium benzoate and sodium ascorbate support the notion that hemocyte cytotoxic activity is a PO-dependent mechanism. Treatments of he…
The Inflammatory Response of Urochordata: The Basic Process of the Ascidians’ Innate Immunity
2018
Ascidians form a widespread marine invertebrate group and are heterogeneous in terms of the taxonomic groups’ evolutionary lineages. The ascidian genomes lack significant homologies for rearranging genes of the vertebrate adoptive immunity. Genome analysis, gene sequencing, and transcriptional profiling have allowed us to disclose upregulation of innate immunity genes and cell labeling with riboprobes and antibodies has identified hemocyte types in tunic and pharynx inflammatory responses. Lymphocyte-like cells are stem cells and their immunocompetence has been proposed. Granulocyte types (compartment/morula cells) and hemocytes with large granules/vacuoles (compartment/morula cells) are ma…
Gender-related variations in hemolymph parameters of Carabus lefebvrei (Coleoptera: Carabidae): HPLC analysis and phenoloxidase activity
2017
We characterized the enzymatic activity of basal and total phenoloxidase and HLPC and SDS- PAGE profiles in hemolymph of Carabus lefebvrei males and females at different reproductive status. The phenoloxidase activity was activated by trypsin and inhibited by phenoloxidase activity specific inhibitor phenylthiourea. Our results demonstrated that both in males and females, there were no significant differences in the basal phenoloxidase activity between reproductive and virgin beetles, while the total phenoloxidase activity increased significantly in virgin specimens. Thus, resources seem to be invested to increase the humoral response in pre-reproductive phase forming a barrier against path…