S. Scippa

Ultrastructural localization of vanadium in the blood cells of Ascidiacea.

X-ray histospectrographic analysis at the scanning and transmission electron microscope (STEM) are made on the blood cells ofPhallusia mamillata Cuvier andCiona intestinalis, to study the ‘direct’ intracellular sites of accumulation of vanadium. The results show a clear accumulation of vanadium on the membrane and in the granules of vacuoles of amebocytes, signet ring cell, compartment cell and traces of metal in the ‘vanadophores’ of vanadocytes.

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.

VANADIUM INHIBITION OF SERINE AND CYSTEINE PROTEASES

A study was made on the effect of vanadium, in both the tetravalent state in vanadyl sulphate and in the pentavalent state in sodium meta-vanadate, and ortho-vanadate, on the proteolysis of azocasein by two serine proteases, trypsin and subtilisin and two cysteine proteases bromelain and papain. Also the proteolysis of bovine azoalbumin by serine proteases was considered. An inhibitory effect was present in all cases, except meta-vanadate with subtilisin. The oxidation level of vanadium by itself did not determine the inhibition kinetics, which also depended on the type and composition of the vanadium containing molecule and on the enzyme assayed. The pattern of inhibition was similar for proteases belonging to the same class. The highest inhibition was obtained with meta-vanadate on papain and with vanadyl sulphate on bromelain.

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.

X-ray microanalytical studies on cryofixed blood cells of the ascidian Phallusia mammillata. III. Quantitative analyses of non-vanadium-accumulating blood cells

Summary The intracellular compartmentation of P, S, Cl, K, Fe, Br, and I in several V non-accumulating blood cells of the ascidian Phallusia mammillata was studied by X-ray microanalysis of freeze-dried cryosections in the scanning transmission electron microscope.

Quantitative X-ray microanalysis of the morula cell of the blood of the ascidian Halocynthia papillosa (Stolidobranchiata)

SummaryThe elemental composition of the morula cell of Halocynthia papillosa blood was studied by X-ray microanalysis with respect to the possible iron accumulation in this cell type. We found various amounts of Na, Mg, P, S, Cl, K, Ca, Fe and Br in the cytoplasm, nucleus and vacuoles. With the exception of a few cells, Ca, Fe and Br were not detected. Thus, the morula cells of the studied species are not iron-rich cells.

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.

Vacuole-containing cells in the body cavity of Phallmia mammillata larvae before and after hatching

Summary The cells of the body cavity of Phallusia mammillata larvae were examined by transmission electron microscopy before hatching, after it and at the beginning of tail retraction. The results revealed the presence—both before and after hatching—of cells with small electron-lucent vacuoles, which might be the precursors of the monovacuolated cells observed at the beginning of tail retraction. These cells share morphological characteristics with the vanadium-accumulating signet ring cells of the blood of adults.

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.

Hatching enzyme immunolocalization during embryonic development of the ascidians Ciona intestinalis and Phallusia mammillata

Summary Different stages of the embryonic development of the ascidians, Ciona intestinalis and Phallusia mammillata, were observed by confocal microscopy after treating embryos with polyclonal antibody raised against C. intestinalis hatching enzyme and after staining with FITC-conjugated second antibody. In both species fluorescence is localized, at the gastrula stage, in the ectoderm. At the subsequent neurula and tail bud stages, in C. intestinalis, the enzyme is localized in the anterior region and tail region, while in P. mammillata it is only present in the anterior region.