Mario de Vincentiis

X-ray microanalytical studies on cryofixed blood cells of the ascidian Phallusia mammillata

SummaryCryofixed blood morula cells of Phallusia mammillata (Cuvier), which are considered to be vanadium-accumulating cells, were examined by X-ray microanalysis using STEM (scanning transmission electron microscopy) and SEM (scanning electron microscopy). It is thought that cryopreparation preserves the native distribution of diffusible elements such as sodium, chlorine, and potassium, and prevents the displacement of vanadium, all of which may occur during conventional preparation. The results show that morula cell globules contain a large amount of sulphur and chlorine, and some sodium, magnesium, bromium and potassium, but very little or no vanadium.

CONTENT AND ULTRASTRUCTURAL LOCALIZATION OF TRANSITIONAL METALS IN ASCIDIAN OVARY

The content of some transitional metals (Ti, V, Cr. Mn. Fe, Cu) in the ovary of Ascidia malaca and Ciona intestinalis and in the gonads ofPolycarpa gracilis has been reported. The metals were localized histospectrographically and ultrastructurally. In the ovaries of C. intestinalis. the quantitative analysis shows a variable content of metals related to the ovary maturative cycle. The iron is localized in the electron dense cytoplasmic granules ofA. malaca oocytcs and in the cytoplasmic dense formation of P. gracilis test cells. Cl, S, Si and P are present in the test, follicles and inierovarian cells of all examined species.

Protease activity in fractionated blood cells of the vanadium accumulating ascidian Phallusia mammillata

Proteolytic activity was studied in the fractionated blood cells of the vanadium accumulating ascidian P. mammillata by separating the cells before measuring their activity. Cells were separated to avoid vanadocyte breakdown and subsequent vanadium diffusion into the assay medium. Our study revealed activity in the morula cell extract that was obtained by sonication and Centricon concentration. After removing part of the extract for enzyme activity assay the remainder was kept at 0 degrees C; it was later found that much of the protein in this latter fraction formed a sediment whereas the protease remained in solution. The serine-protease substrate specificity of the enzyme was measured and the results are discussed in relation to serine protease involvement in immune defense.

Inhibition by vanadate of actomyosin ATPase extracted from ascidians

Abstract 1. 1. Actomyosin ATPase was prepared from each ascidian mantle of 7 species in which vanadium concentrations ranged from 2.4 × 10 −3 M to 5.1 × 10 −7 M intrinsically. 2. 2. Vanadate at concentrations of 10 −5 M to 10 −4 M caused evident inhibition of the enzyme in vitro . 3. 3. However, the actomyosin ATPase is considered to fulfill its function in vivo ; thus, the inhibitory effect on the enzyme of massive levels of vanadium within tissue must be easily overcome by some mechanism.

ENZYMATIC ACTIVITIES RELATING TO THE RESPIRATION AND THE ONSET OF METAMORPHOSIS OF THE ASCIDIAN TADPOLE

The oxygen consumption of a single ascidian larva was measured. After hatching the consumption increases gradually. During the period of tail resorption it also increases gradually, but after the completion of tail resorption the consumption decreases conspicuously.

Observations on an apicomplexan microparasite from the pericardic body of Ciona intestinalis L. (Protochordata)

Summary Specimens of the ascidia Ciona intestinalis L. collected in the Gulf of Naples showed the occurrence within the pericardic body of a microorganism characterized by sporogonial plasmodia and complex sporulation stages. An ultrastructural study revealed several sporonts and plasmodia. The latter showed asynchronous merogonic stages, characterized by merozoites budding at their periphery. These stages were abundant and aggregated at the periphery of the pericardic body among haematic cells, cell debris and other host degenerative material. The merogonic plasmodia had a coccidian-like structure and were the most frequent stages observed in the C. intestinalis pericardic bodies. The microorganism was considered as parasitic and represents a possible re-discovery of Cardiosporidium cionae , a sporozoan described early this century from the same host. Infection by the microparasite appeared implicated in the origin of the pericardic body, considered as an host response to infection.

PROTEOLYTIC ACTIVITY AND VANADIUM INHIBITION IN ASCIDIAN BLOOD CELLS

Abstract Proteolytic activity on azocasein was studied in the hemocytes of vanadium-accumulating ascidians (Phallusia mammillata and Ciona intestinalis) and iron-accumulating ascidians (Halocynthia papillosa and Microcosmus sulcatus). A possible inhibitory role of vanadium on proteolytic enzymes was detected. The following results were obtained: 1. 1. In the neutral range M. sulcatus and C. intestinalis had optimal activity while H. papillosa showed only an activity shoulder, its activity being strongest at alkaline pH. P. mammillata displayed no proteolytic activity at all. Two types of individuals, with high and low activities, were present in H. papillosa at both pHs, and in M. sulcatus at alkaline pH. In C. intestinalis only individuals active at pH 6.5 were observed. 2. 2. In the blood cell sonicate of H. papillosa and M. sulcatus the proteolytic activity was inhibited by ethilenediaminetetraacetate (EDTA) and N-ethylmaleinimide (NEM). 3. 3. P. mammillata blood cells sonicate inhibited proteolytic activity of H. papillosa and M. sulcatus blood cells: this is attributed to the presence of large quantities of vanadium in the blood cells of P. mammillata. 4. 4. Metavanadate, orthovanadate and vanadyl (IV) sulfate inhibited proteolytic activity of H. papillosa and M. sulcatus blood cells. The inhibitory effect showed dependence on the metal ion species, the pH, and the ascidian species assayed.

Ionic dependence and vanadate sensitivity of (Na+, K+)-ATPase isolated from branchial sac of ascidians

Abstract 1. 1. Ion dependence and vanadium-induced inhibition on branchial sac ATPase in five species of ascidian Phlebobranchiata (vanadium-accumulating) and Stolidobranchiata (iron-accumulating) were studied. 2. 2. The ATPase was obtained from the microsomal fraction, which was prepared from each ascidian branchial sac. 3. 3. The ATPase was dependent on Mg 2+ and activated by exogenous Na + + K + . 4. 4. Ouabain inhibited the ATPase activity in vitro , 10 μM to 100 μM vanadate, in vitro , suppressed the (Na + , K + )-ATPase.

THE NUCLEOLUS OF PARACENTROTUS LIVIDUS DURING THE DEVELOPMENT IN THE PRESENCE OF ACTINOMYCIN D

An ultrastructural study of the nucleolus of embryos of Paracentrotus lividus was carried out after treatment with Actinomycin D. It was shown that the fibrillar component of the nucleolus persists in the embryos treated with Actinomycin D in the mesenchyme blastula stage and fixed 24 and 48 hr after fertilization. The results are discussed in relation to the synthesis of RNA.

EFFECT OF THE XANTHOPTERIN ON THE EXPERIMENTAL WOUNDS OF THE CORNEA

Recent studies of Norris and Majnarich (1948) have shown how the xanthopterin accelerates the growing of cultures in vitro of cells derived from different organs (cartilage of rat, spleen, liver, thyroid, pancreas and surrenal capsules). But the same authors (1948, b) show also that the xanthopterin impedes in a high degree the proliferation in vitro of neoplastic cells. Some observations are also interesting (1948 c, d) in which are shown how the serum of the blood of normal persons accelerates the proliferation in vitro of the cells, whereas it impedes the growth of neoplastic cells; the contrary effect, in analogy with the antixanthopterin, shows the serum of the blood of persons affected by tumors. The action the xanthopterin exercise in the acceleration of the growth of cultures in vitro of normal cells deriving from different organs has incited the researches which I explain in the present note. I t was indeed interesting to study the effect of the xanthopterin in vivo on the regeneration of the cellular elements of the cornea after having made a wound in it. The cornea, for its anatomic peculiarity (presence of tissues of epithelial and mesenchymal origin) and above all in the absence of vessels, presents, indeed, many analogies with the cultures of tissues in vitro.