Search results for "Hemocytes"

Modulation of immune responses of Rhynchophorus ferrugineus (Insecta: Coleoptera) induced by the entomopathogenic nematode Steinernema carpocapsae (N…

2014

Aim of this study was to investigate relationships between the red palm weevil (RPW) Rhynchophorus ferrugineus (Olivier) and the entomopathogenic nematode Steinernema carpocapsae (EPN); particularly, the work was focused on the immune response of the insect host in naive larvae and after infection with the EPN. Two main immunological processes have been addressed: the activity and modulation of host prophenoloxidase-phenoloxidase (proPO) system, involved in melanization of not-self and hemocytes recognition processes responsible for not-self encapsulation. Moreover, immune depressive and immune evasive strategies of the parasite have been investigated. Our results suggest that RPW possess a…

Encapsulation Response ofCiona intestinalis(Ascidiacea) to Intratunical Erythrocyte Injection

1997

Abstract Electron microscopic studies on the encapsulation induced by erythrocyte injection into the tunic of the ascidian Ciona intestinalis were carried out. The observations reported in the present paper complete the description previously given of capsule architecture and contribute to the characterization of the cells involved in the inflammatory reaction. The inflamed area is surrounded by an ample and peculiar “three-layered coat” respectively composed of flattened and packed extratunical hemocytes, the monolayered epithelium, and a layer of intratunical electron-dense particles. The latter are also clustered, variously arranged, and distributed in the tunic ground substance. The epi…

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…

A rapid rosetting method for separation of hemocyte sub-populations of Drosophila melanogaster.

2003

Hemocytes, cellular elements of the innate immune system in insects, play a crucial role in the cellular and humoral immune response. Although a significant amount of information has been collected on their differentiation and function, our understanding of hemocyte development is far from complete. Their characterisation is mostly based on morphological criteria. However, molecular markers were recently identified, defining functional subsets by the aid of monoclonal antibodies. Isolated subsets of hemocytes, in sufficient quantity and purity could help to analyse their development in vitro and also to further define their molecular characteristics. Here we describe an antibody-based roset…

Bio-plastic recognition by mussels hemocytes

2023

The growing use of bio-polymers derivatives poses an increasingly pressing problem regarding their environmental sustainability. In particular, it should be still ascertained the claimed absence of direct and indirect influence on ecosystems and the health of living organisms, including humans. Our goal was about assessing the potential effects of poly-lactates and polyhydroxyalkanoates, the most widely used bio polymers classes with promising different applications for replacing conventional plastics on natural aquatic environments. We chose M. galloprovincialis as sentinel species since their extensive filter-feeding activity. When it is exposed to microparticles can bioaccumulate them in…

The hematopoietic niche: a Drosophila model, at last.

2007

The niche provides a specialised microenvironment necessary for maintenance of stem cells in a non differentiated state. While the hematopoietic stem cell (HSC) niche in vertebrates was the first to be recognized, Drosophila niches supporting germline stem cells were characterised first. Recent evidence for the existence of a niche maintaining hematopoietic precursors in Drosophila opens the way to study in vivo the niche/hematopoietic precursors interactions. The availability of a large collection of cell markers, mutants and sophisticated genetic tools makes Drosophila an attractive model for investigating the cellular and molecular mechanisms that are involved in these interactions.

20-Hydroxyecdysone-induced differentiation and apoptosis in the Drosophila cell line, l(2)mbn

2001

20-Hydroxyecdysone has an inhibitory effect on the proliferation of l(2)mbn cells, causes vacuolization and fragmentation of cells, and promotes a strong phagocytotic activity. From several lines of evidence, it can be concluded that 20-hydroxyecdysone induces apoptosis. Long-term video observations following the fate of individual cells, scanning and transmission electron microscopy reveal the typical characteristics of apoptosis: sequestration of small cellular protuberances or larger parts of the cell with nuclear fragments (apoptotic bodies), chromatin condensation, condensation and vesiculation of cytoplasm, whereas the mitochondria retain their normal appearance. The induction of apop…

The cytotoxic activity of Ciona intestinalis (ascidian) unilocular refractile hemocytes versus K562 tumor cells and mammalian erythrocytes involves p…

2010

Univacuolar refractile hemocytes from the tunicate Ciona intestinalis are cytotoxic for mammalian erythrocytes in vitro

1996

A discontinuous, Percoll density gradient was used to separate hemocyte populations from the hemolymph of Ciona intestinalis. Hemocytes from each band were examined for their frequency, morphology, and cytotoxic activity against rabbit and sheep erythrocytes; results were expressed as a percentage of hemolysis. Statistical analysis revealed that only the "univacuolar" granulocytes from Band 5, which contain a vacuole of refractile material, were cytotoxic. Cytotoxic activity was inhibited by sphingomyelin. For the first time in tunicates, lytic activity against erythrocytes was assessed by an assay based on plaque-forming cells. Plaques of lysis were revealed against rabbit erythrocytes but…

Manganese effects on haematopoietic cells and circulating coelomocytes of Asterias rubens (Linnaeus)

2008

Abstract Manganese (Mn) is a naturally abundant metal in marine sediments where it mainly occurs as MnO 2 . During hypoxic conditions it is converted into a bioavailable state, Mn 2+ , and can reach levels that previously have shown effects on immune competent cells of the crustacean, Nephrops norvegicus . Here we investigated if Mn also affects circulating coelomocytes and their renewal in the common sea star, Asterias rubens , when exposed to concentrations of Mn that can be found in nature. When the sea stars were exposed to Mn it accumulated in the coelomic fluid and the number of circulating coelomocytes, in contrast to what was recorded in Nephrops , increased significantly. By using …