Search results for "Styela"
showing 10 items of 20 documents
The identification and localization of two intermediate filament proteins in the tunic of Styela plicata (Tunicata, Styelidae).
2009
The intermediate filament (IF) proteins Styela C and Styela D from the tunicate Styela (Urochordata) are co-expressed in all epidermal cells and they are thought to behave as type I and type II keratins. These two IF proteins, Styela C and Styela D, were identified in immunoblots of proteins isolated from the tunic of Styela plicata. The occurrence and distribution of these proteins within the tunic of this ascidian was examined by means of immunofluorescence and immunoperoxidase techniques, using anti-Styela C and anti-Styela D antibodies. In addition, immuno-electron microscopy of the tunic showed that the two proteins are located in the cuticle layer and in the tunic matrix. These result…
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.
Cellular components and tunic architecture of the solitary ascidian Styela canopus (Stolidobranchiata, Styelidae).
1998
Abstract Cell distribution and tunic morphology in the ascidian Styela canopus were examined by electron microscopy. The observations showed that the outer covering is composed of a thin sinuous cuticle with several protrusions and a deep layer of ground substance. The fibrous component and its arrangement in the tunic were demonstrated: elementary fibrils exhibit a ‘microtubular’ structure and an elliptical cross-sectional shape. Four types of cells were described: clear vesicular tunic granulocytes, tunic microgranulocytes, unilocular tunic granulocytes, and globular tunic granulocytes. Morphofunctional aspects of the tunic tissue and certain phylogenetic relationships are discussed.
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…
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…
Circulating hemocytes and pharyngeal explants of Styela clava release hemagglutinin in vitro
1997
Tunicate blood cells are a mixed population, thus experiments that assay their immunodefense responses, such as release of hemagglutinins, were done to isolate different functional hemocytic types. Two sources of hemocytes from Styela clava were used, the hemolymph and the pharynx (the hemopoietic organ). Hemolymph centrifuged through a discontinuous Percoll gradient yielded four distinct bands of hemocytes. After incubation at 15°C, circulating hemocytes and those from pharyngeal cultures released hemagglutinin after 2 and 30 days. Highest titers were found in B1 (hyaline and compartment cells), B3 (hyaline cells and eosinophil granulocytes), and B4 (hyaline cells and debris). Hemagglutina…
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…
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…
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, …
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…