Localization of antimicrobial peptides in the tunic of Ciona intestinalis (Ascidiacea, Tunicata) and their involvement in local inflammatory-like reactions.

Tunicates comprising a wide variety of different species synthesize antimicrobial peptides as important effector molecules of the innate immune system. Recently, two putative gene families coding for antimicrobial peptides were identified in the expressed sequence tag database of the tunicate Ciona intestinalis. Two synthetic peptides representing the cationic core region of one member of each of the families displayed potent antibacterial and antifungal activities. Moreover, the natural peptides were demonstrated to be synthesized and stored in distinct hemocyte types. Here, we investigated the presence of these natural peptides, namely Ci-MAM-A and Ci-PAP-A, in the tunic of C. intestinalis considering that the ascidian tunic is a body surface barrier exposed to constant microbial assault. Furthermore, as the tunic may represent a major route of entry for pathogen invasion after its damage we monitored the location of these peptides upon a local inflammatory-like reaction induced by injection of foreign cells. Using immunocytochemistry and electron microscopy both peptides were localized to the tunic and were massively present in granulocytes of inflamed tissue. Conclusively, antimicrobial peptides may constitute a chemical barrier within the tunic of urochordates.

Different phenotypes of colon carcinoma cells interacting with endothelial cells: role of E-selectin and ultrastructural data.

Adhesion molecules are intimately involved in the process of tumour progression. Among them, E-selectin is an inducible endothelial cell adhesion molecule that plays a role in the interactions of neoplastic cells with the endothelium. These interactions are required for the trans-endothelial migration of tumour cells that leads to the growth at the new sites. Since the detailed events in the early phase of metastasis still remain poorly defined, our study has undertaken an electron-microscopic analysis of the interactions of human colon carcinoma cells with endothelial cells as well as an analysis of the effect of recombinant purified E-selectin in the cell signalling involved in colon cancer cell malignant phenotype. Results revealed that SW480 and T84 colon cancer cell lines show different features, different adhesion kinetics, a different cytoskeletal organization, and a different tyrosine phosphorylation pattern when seeded on an endothelial cell monolayer or recombinant E-selectin. In particular T84 cancer cells adhere more efficiently to the E-selectin and this interaction is associated with pronounced morphological changes, actin redistribution and filopodial processes, and an increase in tyrosine phosphorylation of different proteins. These data support the hypothesis that E-selectin ligand is not only a cell-cell adhesion molecule but also initiates a signalling transduction pathway inside the cells.

E-selectin modulates the malignant properties of T84 colon carcinoma cells.

The extravasation of metastatic cells is regulated by molecular events involving the initial adhesion of tumor cells to the endothelium and subsequently the migration of cells in the host connective tissue. E-selectin on endothelial cells and sialyl Lewis X carbohydrate component on tumor cells are mainly involved in the adhesion of colon carcinoma cells to the endothelium of target organ. Interaction of T84 colon cancer cells to purified E-selectin in vitro caused an increase in the tyrosine phosphorylation of a number of proteins as well as the modulation of cellular properties correlated to the metastatic phenotype. Specifically, E-selectin-stimulated actin reorganization, increased collagenase secretion, and induced cell migration. Treatment of T84 cells with herbimycin A inhibited cell adhesion as well as selectin-induced increase of cell migration, and cytoskeleton assembly. Our data demonstrate that binding of cancer cells to E-selectin starts signal transduction pathways which may affect the tumor metastatic abilities.

Hemocyte migration during inflammatory-like reaction of Ciona intestinalis (Tunicata, ascidiacea).

Following an injuring factor such as the injection of erythrocytes into the tunic of Ciona intestinalis, an inflammatory-like response occurs and blood cells are massively involved in these mechanisms. Electron microscope observations illustrate the infiltration and migration of blood cells throughout the mantle epithelium into the tunic and show several prominent morphological changes.

Encapsulation response of Ciona intestinalis (Ascidiacea) to intratunical erythrocyte injection.

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 epithelial cells appear to be undergoing an active secretory phase; in several regions they also show discontinuities and organule and surface changes. The infiltrating hemocytes, mainly globular and unilocular granulocytes, appear frequently to be degranulating and in relation with electron-dense particles, net-like fibrous materials, and fine membranes. The involvement of morula-shaped granulocytes is discussed, as well as possible relationships with the melanization process, and finally analogies in the structural organization with the inflammatory reactions induced in other invertebrates. A schematic drawing, based on all available observations of the capsule architecture, is presented in order to reconstruct the entire inflamed area and illustrate the relative fine features.

Encapsulation response of Ciona intestinalis (Ascidiacea) to intratunical erythrocyte injection. I. The inner capsular architecture.

Previous studies on the ascidian Ciona intestinalis have shown that an encapsulation response is experimentally induced by inserting vertebrate erythrocytes into the tunic, which initiates a massive inflammatory cell infiltration to isolate the injured area. Several hemocytes contribute to capsule formation, destruction of the foreign cells, tunic regeneration, and wound healing. The fine features of some inflammatory cell types are described although the complete capsular structure is not yet reported. Accordingly, the present investigation further examines various aspects of this cellular reaction against erythrocytes and, for the first time, presents the involvement of extratunical circulating hemocytes and mantle epithelium in capsule formation.

Activation of the acrosome reaction after treatment with human follicular fluid. A morphofunctional evaluation useful for in vitro fertilization.

Studies aided by transmission electron microscopy were made in order to evaluate the occurrence and efficiency of the human follicular fluid in the activation of the processes leading to the acrosome reaction; quantitative, qualitative and morphological data and relative evaluations are here presented. The effects of the human follicular fluid were compared with those determined by other types of treatment, semen untreated, Pellet-Swim-up, and Centrifugation on Discontinuous Percoll Gradient. The transmission electron microscope observations permitted to evaluate the percentage of sperm with an activation of the acrosome reaction in the different groups. The analysis of the data showed a statistically relevant difference (P < 0.001) among the first group (Control group) and the SU group, the MP group and the hFF group, regarding the sperm with AR activation. The sperm treatment with 50% diluted hFF represents an important option to the preparation protocols of the semen samples useful for ART.

Retinyl ester hydrolases in retinal pigment epithelium.

In bovine retinal pigment epithelium membranes we have found three hydrolases which were active against trans-retinyl palmitate. This was possible by assaying different subcellular fractions as a function of pH in the range 3-9. Detection of these activities has been favored by the use in the enzyme assay of Triton X-100, which has an activating effect up to a concentration of 0.03% at a detergent-protein ratio of about 1.5-3.0. Apparent kinetic parameters for the retinyl ester hydrolases have been determined after a study of the optimization of assay conditions. Vmax values for hydrolases acting at pH 4.5, 6.0, and 7.0 were, respectively, 156, 55, and 70 nmol/h/mg. To identify the subcellular site for these hydrolytic activities, assays of marker enzymes from various organelles in each subcellular preparation were carried out, demonstrating the lysosomal origin of the pH 4.5 retinyl ester hydrolase and the microsomal origin of the pH 6.0 retinyl ester hydrolase and suggesting that the pH 7.0 retinyl ester hydrolase originates from the Golgi complex.

Fine structural observations of the granulocytes involved in the tunic inflammatory-like reaction of Ciona intestinalis (Tunicata).

Erythrocytes injected into the tunic of Ciona intestinalis induced an inflammatory-like reaction which can cause lysis of the neighboring tissue. Electron microscopy observations of the granulocytes of the injured tunic show lysosomic figures and degranulations features suggesting granulocyte involvement in the destructive process.