Characterization of haemolytic activity of coelomocytes of Holothuria tubulosa

Phylogenetic analysis recognizes echinoderms as a key group of deuterostomes, therefore the species in this group are useful for the study of the evolution of innate immunity responses. In addition, this marine invertebrate lives in coastal and estuarine waters that are directly exposed to potentially pathogenic microorganisms and stressful anthropogenic factors. Coelomocyte populations seem to be essential to immune-defence functions such as phagocytosis, ROI production, cytotoxicity, synthesis and release of antimicrobial substances including lectin, cytokine, C3-like expression, prophenoloxidase activity and capsule formation. Holothurians’ coelomocyte populations contain several coelomo…

Erythrocyte agglutinins in the blood of certain Ascidians

Plasma from Ciona intestinalis, Phallusia mamillata and Ascidia malaca possess hemagglutinin for a variety of erythrocytes. Results obtained by physical and chemical treatments suggest that hemagglutinin for Phallusia mamillata and Ascidia malaca may be a protein or a protein-like substance.

Cytology, Histology and Histochemistry

Phenoloxidase-dependent cytotoxic mechanism in ascidian (Styela plicata) hemocytes active against erythrocytes and K562 tumor cells.

The cytotoxic activity against rabbit erythrocytes (RE) and human K562 tumor cells by Styela plicata hemocytes was significantly related to the phenoloxidase (PO) which converts phenols to quinone and initiates the melanogenic pathway. The effector hemocyte population, separated in a Percoll density gradient band, enriched in a granulocyte type named "morula cells", was examined with RE in a hemocyte cytotoxic assay and plaque forming cell assay. Inhibition experiments with the copper chelating agents 1-phenyl-2-thiourea and tropolone, the substrate analogue sodium benzoate and sodium ascorbate support the notion that hemocyte cytotoxic activity is a PO-dependent mechanism. Treatments of he…

Biochemical genetic differentiation between Pomatoschistus marmoratus and P. tortonesei (Pisces, Gobiidae).

Several diagnostic genetic markers were identified in Pomatoschistus marmoratus and P. tortonesei using polyacrylamide gel electrophoresis (PAGE) of allozymes. Twenty-one loci were resolved, including the electrophoretic pattern of muscle proteins. The MDH*, PGM- 1,2*, EST-1,2*, FUM* and PGI-2* loci exhibited different alleles which were fixed for the two species being analysed. Genetic distance, as calculated by Nei’s index, showed a value of 0·413. Environmental hypersalinity, could have influenced the geographical distribution of P. tortonesei.

Cytotoxic Activity of Tunicate Hemocytes

Tunicates (protochordates) are filter-feeding marine invertebrates with a worldwide distribution. In their larval form, they exhibit many of the features characteristic of the vertebrates. The larva, with a tail, notochord, and dorsal neural tube, upon settlement undergoes a remarkable metamorphosis in which it loses most of its chordate characteristics and becomes a sessile invertebrate adult. Thus, due to these characteristics, tunicates are considered to be the most primitive members of the phylum Chordata. Owing to their position in the phylogenetic line leading to the vertebrates, they have attained importance as experimental organisms and have been examined by researchers from a varie…

Separated hemocyte populations from the ascidian Ciona intestinalis contain and release in vitro opsonizingCa++-independent and β-galactoside specific lectins

Circulating hemocytes and pharyngeal explants of Styela clava release hemagglutinin in vitro

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…

The ascidian prophenoloxidase activating system

Phenoloxidases/tyrosinases initiate melanin synthesis in almost all organisms, and are involved in different biological activities such as the colour change of human hair and the browning or blackening of fruit skin etc. In many invertebrates, defence reactions are linked to phenoloxidase activity and/or melanization. Contacts with foreign molecules are able to trigger the prophenoloxidase (proPO) system that requires serine protease cleavage for activating the zymogen to phenoloxidase (PO). It is generally accepted that the proPO system is fully expressed in arthropods, and, recently, progress in the regulation of crustacean and insect proPO activation steps have been achieved. After cells…

THE EXPRESSION OF IMMUNE-RELATED GENES IS INVOLVED IN ASCIDIAN DEVELOPMENT

Molluscan antimicrobial peptides, a review from activity-based evidences to computer-assisted sequences

Antimicrobial peptides (AMPs) represent the most universal immune effectors. Molluscs constitute the second largest animal phylum, after Arthropods, in term of number of species. Only a negligible number has been investigated regarding AMPs. The choice of the species to be studied relied on their economical importance and availability. First studies on molluscan AMPs dated from 1996 and were based on biological activities of biochemical-purified fractions. Such approach released all the original structures we know, with biological activity sometimes different from one isoform to another. Then, molecular biology techniques were applied to molluscan AMPs starting in 1999. Complete screening o…

Detection of vitellogenin in a subpopulation of sea urchin coelomocytes.

Sea urchin vitellogenin is a high molecular weight glycoprotein, which is the precursor of the major yolk protein present in the unfertilized egg. Vitellogenin processing into the major yolk protein and its further enzymatic cleavage during sea urchin embryonic development, has been extensively described, and the adhesive properties of the processed molecule have been studied. The function of vitellogenin in the adult, where it has been found in the coelomic fluid of both male and female individuals, is still unknown, although its role on promoting the adhesion of embryonic cells has been shown. In this report we describe the detection of vitellogenin in lysates of whole circulating coelomo…

Electrophoretic study on two morphologically distinguishable populations of Paracentrotus lividus (Echinodermata) from distinct areas of the mediterranean coast.

A Biochemical Genetic Study of Isoenzyme Polymorphism within and between Two Populations of Atherina Boyeri Risso

Allozymic variation of 20 loci was investigated in two samples of Atherina boyeri collected in the Mediterranean Sea from the coast of Trappeto and Marsala Lagoon (Sicily, Italy). Five loci were polymorphic (PGM*, EST-1,2*, SOD-2*, PGI-2*) and appeared to be in Hardy-Weinberg equilibrium. A significant Fst mean value (0.02) (G = 23.77, P < 0.05, df = 5) showed that the samples can be considered as two distinct local populations and supports previous morphometric discrimination.

Spermatocyte Chromosomes in Some Species of the Family Aplysiidae (Gastropoda, Opisthobranchia)

SUMMARYCounting spermatocyte bivalents, we have determined the haploid number n = 16 for Aplysia depilans and A. punctata, and n = 17 for A. limacina. We have confirmed n = 17 for Bursatella leachii. Male diakinetic bivalents are probably chiasmatic in all the species examined. The orders Nudibranchia and Notaspidea, possessing haploid values of 13 and 12 chromosomes respectively, seem to be more evolved than the other orders of the sub-class Opisthobranchia.