Search results for "Ascidia"

Influence of cadmium on the morphology and functionality of haemocytes in the compound ascidian Botryllus schlosseri

2013

In order to get insights into the effects of cadmium (Cd) on cell morphology and functions, we exposed haemocytes of the colonial ascidian Botryllus schlosseri to sub-lethal concentrations of CdCl(2). Results indicate that Cd hampers haemocyte spreading and phagocytosis in a dose-dependent way, through the alteration of the actin cytoskeleton. In addition, the metal decreases the stability of the internal membranes, as revealed by the Neutral Red assay. The fraction of cells showing positivity for the lysosomal enzyme acid phosphatase is also reduced in the presence of Cd, whereas the number of cells responsive to the Annexin-V assay and showing chromatin condensation increases, suggesting …

COMPARATIVE ULTRASTRUCTURAL INVESTIGATION ON THE ADHESIVE PAPILLAE OF THE SWIMMING LARVAE OF THREE ASCIDIAE SPECIES

2008

Ascidian swimming larvae bear three peculiar organs of ectodermic origin, named “palps” or adhesive papillae, located in the anterior region of cephalenteron. Term “adhesive” is correlated to one of the function of these structure based on secretion of an adhesive substance which enables swimming larvae to adhere to a substratum. Recently a sensory function has also been described in some Phlebobranchia papillae with a simple morpho-functional organization. There are few ultrastructural investigations in literature, sometimes disputed, able to make clear papillae cells functions. To clarify this problem, a comparative investigation has been carried out, just in this work, about ultrastructu…

Single giant larvae ofAscidia malaca from double eggs

1969

E stata operata la fusione due a due di uova vergini diAscidia malaca. Le uova giganti cosi ottenute, sono state successivamente fecondate e il loro sviluppo e stato seguito. Da esse sono state ottenute in numerosi casi delle larve giganti che mostravano unicita in tutti i loro organi. L'osservazione dell'uovo gigante, dopo fecondazione, permette di asserire che le larve giganti sono triploidi.

The conservation and diversity of ascidian cells and molecules involved in the inflammatory reaction: The Ciona robusta model

2021

Ascidians are marine invertebrate chordates belonging to the earliest branch (Tunicata) in the chordate phylum, therefore, they are of interest for studying the evolution of immune systems. Due to the known genome, the non-colonial Ciona robusta, previously considered to be C. intestinalis type A, is a model species for the study of inflammatory response. The internal defense of ascidians mainly relies on hemocytes circulating in the hemolymph and pharynx. Hemocytes can be in vivo challenged by LPS injection and various granulocyte and vacuolated cell populations differentiated to produce and release inflammatory factors. Molecular biology and gene expression studies revealed complex defens…

A GC-MS method for hormone analysis and modulation of ovarian histology and steroidogenic genes by TBT and Bisphenol-A in Ciona intestinalis

2009

Sex hormone profiles in Ciona intestinalis (Ascidiacea Urochordata) and their modulation by Tributyltin (TBT)

2008

The hydrophilie of the larval test of Ascidiae: functional role played by test cells

2012

Ascidian swimming larvae are entirely surrounded by a hyaline extracellular coat, called as tunic or test, on which numerous test cells adhere. The functional role played by test cells in larvae of various ascidian species consists in depositing submicroscopic structures known as ornaments and/or substances of proteoglycan nature in the larval test surface. The deposition of ornaments would render the larval test hydrophilic and thus allow the larvae to swim being immersed in sea water. Ultrastructural investigations reported in literature on larvae of Cionidae and Ascididae families have not evidenced the presence of ornaments in the swimming larval test. For these Ascididae families it ha…

Microscopic features of the tunic in young Styela canopus (Tunicata, Styelidae)

The tunic is a unique tissue in metazoans covering the epidermis of ascidians and other tunicates. The tunic is a multifunctional tissue that provides support, mechanical rigidity, and protection against infection and predation. The outermost surface of it is covered by a thin continuous layer called tunic cuticle. The tunic cuticle density and integrity must be maintained during the growth of the animal after metamorphosis, as it represents the primary body surface barrier preventing the mechanical damage. Using transmission electronic microscopy we attempted to characterize the cuticle morphology of young Styela canopus, a solitary ascidian (Styelidae), in comparison with the cuticle arch…

Early stages of test formation in larva of Ascidia malaca (Tunicata, Ascidiacea): ultrastructural and cytochemical investigations.

2003

Abstract The swimming larvae of ascidians are entirely covered by a hyalin coat called tunic, or test. This covering consists of two cuticular layers, C 1 and C 2 , which surround an inner compartment composed of an amorphous hyalin matrix with numerous fibrils dispersed inside. Data from the literature agree on the key role played by the cells of the larval ectodermic layer in the synthesis and secretion of larval test components. In the present article are reported ultrastructural and cytochemical investigations made during test formation in the swimming larva of Ascidia malaca . Besides confirming the role played by ectodermic cells during the early stages of test formation, the investig…

Cloning and expression of a type IX-like collagen in tissues of the ascidian Ciona intestinalis

2002

Collagens are highly preserved proteins in invertebrates and vertebrates. To identify the collagens in urochordates, the total RNA extracted from the pharynx of the ascidian Ciona intestinalis was hybridized with a heterologous probe specific for the echinoderm Paracentrotus lividus fibrillar type I-like larval collagen. Using this probe, two main bands (i.e. 6 and 2.8 kb mRNA) were observed on Northern blot hybridization. The cDNA library prepared from poly(A)+RNA extracted from pharyngeal tissue was screened and a cDNA that specifies a type IX-like collagen was identified. This molecule presents a conceptual open reading frame for a protein containing 734 amino acids. In particular, we sh…