Search results for "Styela plicata"
showing 10 items of 14 documents
Evaluation and comparison of trace metal accumulation in different tissues of potential bioindicator organisms: Macrobenthic filter feedersStyela pli…
2016
Trace metal concentrations were measured in different tissues of Sabella spallanzanii, Styela plicata, and Mytilus galloprovincialis collected in the Termini Imerese Harbor (Sicily, Italy) to evaluate the potential use of these species as bioindicators. Higher bioaccumulation factors (BAFs) were calculated in the tube of S. spallanzanii, except for As, which had a higher BAF in the branchial crown of the same species. Regarding the other species analyzed, higher BAFs were found in the digestive gland of M. galloprovincialis. An exception was Pb, which was significantly more concentrated in the branchial basket and tunic of S. plicata. The BAFs calculated in the present study show that all t…
The ascidian Styela plicata hemocytes as a potential biomarker of marine pollution: In vitro effects of seawater and organic mercury.
2017
Toxic metals, such as mercury, contribute substantially to anthropogenic pollution in many estuarine environments. Animals living in those environments, particularly invertebrate filter feeders like tunicates, can be used as bioindicators. In an attempt to identify cellular markers for revealing pollution, this study examined in vitro the effects of different concentrations of methyl mercury on Styela plicata hemocytes. The harvested hemocytes from S. plicata that were exposed to the metal had a significant mortality, cellular count and morphometric alterations. These findings provided evidence of MeHg immunotoxic effects on S. plicata, resulting in hemocyte death and morphological changes …
In vitro effects of methylmercury on ascidian (Styela plicata) immunocyte responses
2007
This study shows that high methylmercury concentrations are cytotoxic for Styela plicata hemocytes, whereas sublethal concentrations affect immunocyte responses. Moreover, hemocytes exposed to the xenobiotic present a significantly enhanced phenoloxidase activity as revealed in the hemocyte lysate supernatant compared with the control. Although the cytotoxic activity of S. plicata hemocytes toward rabbit erythrocytes is a PO-dependent cell-target reaction due to quinone products, it was significantly decreased by suitable methylmercury concentrations in the medium. The same xenobiotic concentrations decreased the hemocyte phagocytic activity toward yeast. In both the responses cell-target c…
Ultrastructural aspects of naturally occurring wound in the tunic of two ascidians: Ciona intestinalis and Styela plicata (Tunicata).
2015
Efficient wound healing is essential for all animals from insects to mammals. Ciona intestinalis and Styela plicata are solitary ascidians belonging to urochordates, a subphylum that occupies a key phylogenetic position as it includes the closest relative to vertebrates. Urochordate first physical barrier against invaders is the tunic, an extracellular matrix that is constantly exposed to all kinds of insults. Thus, when damage occurs, an innate immune response is triggered to eliminate impaired tissue and potentially pathogenic microbes, and restore tissue functionality. Ultrastructural aspects of the tunic in the wound healing process of two ascidians are described. In the injured areas, …
Effects of tributyltin(IV) chloride on fertilization of Styela plicata (Ascidiacea: Tunicata): II. Scanning and transmission electron microscopy stud…
2003
The morphological aspects of Styela plicata fertilization after treatment with tributyltin(IV) chloride are described by means of scanning and transmission electron microscopy investigations. Alterations have been shown both on female and male gametes; spermatozoa, all the egg envelopes and the mitochondria of the egg cortical cytoplasm are modified in relation to incubation time. As a consequence, the damage to gametes blocks sperm-egg interaction and fertilization does not occur. Copyright © 2003 John Wiley & Sons, Ltd.
Phenoloxidase characterization in vacuolar hemocytes from the solitary ascidian Styela plicata
1995
Phenoloxidase (PO) activity was shown in lysates of Styela plicata hemocytes assayed spectrophotometrically by means of L-Dopa oxidation without divalent cations. Trypsin and chymotrypsin pretreatment and preincubation with microbial lipopolysaccharides significantly activated PO, whereas laminarin or zymosan were ineffective. Soybean trypsin inhibitor, tropolone, and phenylthiourea, but not benzamidine, were inhibitors. Finally, hemocytes were separated by a discontinuous Percoll density gradient to determine which cells were active. PO activity was demonstrated, by both biochemical and cytochemical assays, in the separated fraction enriched mainly with the globular granulocytes called mor…
Rare earths, zirconium and hafnium distribution in coastal areas: The example of Sabella spallanzanii (Gmelin, 1791)
2016
The Zr, Hf, Y and lanthanide (REE) distribution in biological tissues of Sabella spallanzanii and Styela plicata species collected from two harbours from the northern Sicily is studied for providing information regarding the Zr, Hf and REE uptake from the environment. Previous studies determined the fractionation of dissolved REE scavenged on binding sites onto biological surfaces. By comparing the recognised shale-normalised REE patterns of studied samples with evidence from reference data, the observed behaviour of these elements in biological tissues of Sabella spallanzanii and Styela plicata is interpreted to result from the preferential uptake of intermediate REE onto carboxylic sites.…
Phenoloxidases in ascidian hemocytes: characterization of the pro-phenoloxidase activating system.
2003
The phenoloxidase (PO) activity of the hemocytes lysate supernatant from three ascidians species, assayed by means of 3-methyl-2-benzothiazolinone hydrazone hydrochloride, have been compared. PO-containing hemocytes were identified by a cytochemical reaction and the enzymatic activity measured by a spectrophotometric assay of lysate supernatant from hemocyte populations separated on a discontinuous Percoll density gradient. In Styela plicata, the enzyme appeared to be contained in morula cells only. In Ciona intestinalis, PO activity was shown in univacuolar refractile granulocyte and granular hemocyte. In Phallusia mammillata both compartment cell and granular hemocytes were positive. Enzy…
Evaluation and comparison of trace metals accumulation in different tissues of potential bioindicator organisms: Macrobenthic filter feeders Styela p…
2015
Trace metal concentrations were measured in different tissues of Sabella spallanzanii, Styela plicata and Mytilus galloprovincialis collected in Termini Imerese harbor, located in Sicily (Italy), in order to evaluate the potential use of these species as bioindicators. The higher bioaccumulation factors (BAFs) were calculated in tube of Sabella spallanzanii, except for As which shows the higher BAF in branchial crown of the same specie. Regarding the other species analyzed, higher BAFs were found in the digestive gland of Mytilus galloprovincialis. An exception is represented by Pb that is significantly more concentrated in branchial basket and tunic of Styela plicata. The BAFs here calcula…
Immunological Activity of Ascidian Hemocytes
2001
In ascidians, various hemocyte types and their differentiation stages may be responsible for several immune functions. A central role in the immune effector mechanisms can be assigned to PO-containing hemocytes and prophenoloxidase system. Morula cell in Styela plicata and univacuolar refringent granulocyte in Ciona intestinalis, a probable intermediate stages in the differentiation pathway of morula cell, may be cytotoxic cells. They are involved in immune reactions of solitary and colonial ascidians. We have shown that they are provided with a PO-linked spontaneous cytotoxic activity and recognize mammalian erythrocytes or tumor cells markers. The toxic molecules can be radical oxygen int…