Search results for "hemolymph"
showing 10 items of 126 documents
Cytotoxic activity of Ciona intestinalis (Tunicata) hemocytes: Properties of the in vitro reaction against erythrocyte targets
1993
Hemocytes (effectors) of Ciona intestinalis showed a natural cytotoxic capacity (HCA) when assayed in vitro against erythrocytes (targets). Cytotoxic cells lysed, to a variable extent, rabbit (RE), human (A, B, O), guinea pig, and sheep (SE) erythrocytes. Hemocyte cytotoxic activity (HCA) assayed against SE is a calcium-dependent reaction, occurs rapidly (15-30 min), at 25-37 degrees C over a wide range of pH (5.4-8.0). Assays were carried out using: 1) the medium in which hemocytes were maintained, 2) the soluble portion of hemocyte lysates, and 3) debris prepared from hemocyte lysates. Results suggest that HCA is a cell-mediated process that requires effector-target cell contacts. Anti-SE…
Ciona robusta hemocyte populational dynamics and PO-dependent cytotoxic activity
2020
Hemocyte populations from the ascidian Ciona robusta, separated through a Percoll discontinuous density gradient, are further characterized by May-Grünwald-Giemsa staining and a cytochemical reaction for phenoloxidase. Variability in cell density, acidophilic property and phenoloxidase activity suggest multiple hemocyte type populations, cell lineages and morphotypes that may be involved in distinct cellular responses. Therefore, unilocular refractile granulocytes, typical of this ascidian species, enriched in a fraction separated from the hemolymph show in vitro phenoloxidase-dependent cytotoxic activity against mammalian erythrocytes and a tumor cell lineage, in addition the properties li…
Diversity of stonefly hexamerins and implication for the evolution of insect storage proteins
2007
Hexamerins are large storage proteins of insects in the 500 kDa range that evolved from the copper-containing hemocyanins. Hexamerins have been found at high concentration in the hemolymph of many insect taxa, but have remained unstudied in relatively basal taxa. To obtain more detailed insight about early hexamerin evolution, we have studied hexamerins in stoneflies (Plecoptera). Stoneflies are also the only insects for which a functional hemocyanin is known to co-occur with hexamerins in the hemolymph. Here, we identified hexamerins in five plecopteran species and obtained partial cDNA sequences from Perla marginata (Perlidae), Nemoura sp. (Nemouridae), Taeniopteryx burksi (Taeniopterygid…
Molecular characterization of hemocyanin and hexamerin from the firebrat Thermobia domestica (Zygentoma).
2008
Hexapods possess a tracheal system that enables the transport of oxygen to the inner organs. Although respiratory proteins have been considered unnecessary in most Hexapoda for this reason, we recently showed the presence of a functional hemocyanin in the stonefly Perla marginata. Here we report the identification and molecular characterization of a hemocyanin from Zygentoma (Thysanura). We obtained the full length cDNA of two distinct subunit types from the firebrat Thermobia domestica, and partial sequences of the orthologs from the silverfish Lepisma saccharina. The native T. domestica hemocyanin subunits both consist of 658 amino acids, but a signal peptide for transmembrane transport i…
A respiratory hemocyanin from an insect.
2004
Insects possess an elaborate tracheal system that enables transport of gaseous oxygen from the atmosphere directly to the inner organs. Therefore, the presence of specialized oxygen-transport proteins in the circulatory system of insects has been considered generally unnecessary. Here, we show for the first time, to our knowledge, the presence of an ancestral and functional hemocyanin (Hc) in an insect. In the hemolymph of nymphs and adults of the stonefly Perla marginata , a hexameric Hc was identified, which consists of two distinct subunit types of 659 and 655 amino acids. P. marginata Hc displays cooperative oxygen binding with a moderately high oxygen affinity [(half-saturation pressu…
A hemocyanin from the Onychophora and the emergence of respiratory proteins
2002
The velvet worms (Onychophora) are considered living fossils and are closely related to the Euarthropoda. Onychophora possess a tracheal system for respiratory function, but oxygen-transport proteins have been considered unnecessary. Here, we show that the hemolymph of the Epiperipatus sp. (Onychophora: Peripatidae) contains an arthropod-type hemocyanin, demonstrating that such protein exists outside the Euarthropoda. Thus, the evolution of oxygen carriers preceded the divergence of the Onychophora and Euarthropoda and was most likely linked to the evolution of an efficient circulatory system in a low-oxygen environment. The cDNA of the Epiperipatus hemocyanin subunit comprises 2,287 bp an…
Key Disulfide Bonds in an Insect Hormone Binding Protein: cDNA Cloning of a Juvenile Hormone Binding Protein of Heliothis virescens and Ligand Bindin…
1995
The hemolymph juvenile hormone binding protein (JHBP) from the early fifth instar larvae of Heliothis virescens (Lepidoptera, Noctuidae) has been purified, and three cDNA clones for this protein have been isolated from a fat body cDNA library constructed in bacteriophage λZAP XR. The deduced amino acid sequence of the full-length clone predicts a mature protein consisting of 224 residues, a molecular mass of 24 976 Da, and a p/ of 5.29. Comparison of the amino acid sequence to that of the previously described JHBP from Manduca sexta shows 51 % overall identity with highly conserved N- and C-terminal regions. One of the three clones bound photoactivatable analogs of juvenile hormones with mu…
Small Nitrogenous Compounds
1994
Because of the constant turnover of proteins, protein-bound and free amino acids exist in a dynamic equilibrium. The intracellular pool of free amino acids, which is replenished by the hydrolysis of existing proteins, by uptake from the intercellular space and by de novo synthesis, is available for protein synthesis and for the many other metabolic processes dependent upon amino acids. The concentration of free amino acids is always lower than that of the protein-bound residues, one limiting factor being the strong osmotic effects of such low molecular weight compounds. Thus, there is no specific amino acid store in an organism; it is more the case that enzymes and structural proteins thems…
2-Deoxyecdysone is a circulating ecdysteroid in the beetle Zophobas atratus
1997
A qualitative analysis of ecdysteroids has been performed during the post-embryonic development of the tenebrionid beetle, Zophobas atratus, by high performance liquid chromatography (HPLC) combined with enzyme immunoassay (EIA) using two different antibodies. Three HPLC peaks were found to be immunoreactive, in hemolymph extracts of both sexes. Moreover, these peaks had ecdysteroid-like UV spectra, determined using a photodiode array detector. The use of two different HPLC systems (reverse and normal phases), in combination with two different EIA antibodies, allowed us to identify 20-hydroxyecdysone (20E) and ecdysone (E), as the two main ecdysteroids, but also suggested the presence of 2-…
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…