Oscarella Lobularis Research Articles

Genetic and cytological divergence between colour morphs of the Mediterranean spongeOscarella lobularisSchmidt (Porifera, Demospongiae, Oscarellidae)

The demosponge Oscarella lobularis (Schmidt, 1862) has been reported from various localities throughout the world and is abundant in many areas. It is considered to be morphologically very variable, and morphs of different colour or texture can be found living sympatrically. Samples of a soft violet morph and of cartilaginous blue, yellow and green morphs were collected from the Mediterranean Sea, near Marseilles. The genetic divergence of the four morphs was estimated by enzyme electrophoresis, and cytological differences were studied using light and transmission electron microscopy. The cartilaginous morphs were genetically practically identical, but the soft violet morph was diagnostically different from the sympatric samples of the blue and green morphs and from the allopatric yellow morph at most of the genetic loci studied (genetic identity, I ≈ 0·25). The high genetic divergence was associated with consistent differences in morphology and cytology between the violet morph and the other colour morph...

Isolation of five new 5α-hydroxy-6-keto-Δ 7 sterols from the marine sponge Oscarella lobularis

Five novel sterols isolated from the marine sponge Oscarella lobularis have been identified on the basis of spectral arguments: cholest-7-ene-3β,5α-diol-6-one ( 1), cholesta-7,22E-diene-3β,5α-diol-6-one ( 2), 24-methylcholesta-7,22E-diene-3β,5α-diol-6-one ( 3), 24-methylcholesta-7,24(28)-diene-3β,5α-diol-6-one ( 4), and 24-ethylcholest-7-ene-3β,5α-diol-6-one ( 5). (Steroids 56:337–340, 1991)

Ultrastructural study of spermatogenesis inOscarella lobularis(Porifera, Demospongiae)

Summary The various phases of spermatogenesis in the demosponge Oscarella lobularis were studied by electron microscopy. Spermatogenesis occurs within spermatic cysts, which are presumed to derive from choanocyte chambers by transformation of choanocytes into spermatogonia. Germ cells develop asynchronously within spermatocysts, and cytoplasmic bridges, indicating incomplete cells division, connect several germ cells. Attached spermatogonia suggest gonial generations. Spermatocytes I typically show the presence of synaptonemal complexes indicating meiotic divisions. Spermatocytes II have a small size probably because of the meiotic divisions of spermatocytes I. Spermatids are characterized by an acrosome, a big mitochondrion and a peripheral sheath of condensed chromatin surrounding a clearer central area in the nucleus. The mature spermatozoon shows a lateral flagellum and a flattened acrosome capping the nucleus. The phylogenetic implications of some features of the spermatozoon are suggested.

The vacuolar cells of Oscarella lobularis (Porifera, Demospongiae): Ulatrastructural organization, origin, and function.

This work is concerned with the ultrastructural organization and some histochemical features of the vacuolar cells of the demosponge Oscarella lobularis. Vacuolar cells are characterized by large clear vacuoles containing an aqueous fluid. They are commonly found in the mesohyl of this sponge and tend to constitute a sort of parenchyma in the choanosome. Mobile cells of the mesohyl appear to differetiate into vacuolar cells through the progressive formation of wide cytoplasmic lacunae. We have identified four types of cells showing progressive transformation toward the vacuolar cell type. Precursors (types 1-4) of the vacuolar cells probably derive from endopinacocytes, since they share several histochemical and ultrastructural characteristics with them. Our data support the notion that vacuolar cells are involved in the synthesis of collagen, act as a mechanical support of the sponge body, and are eventually extruded from the sponge through the canals of the aquiferous system.

A sponge with acrosome: Oscarella lobularis

In this paper we describe the presence of a true acrosome in the Homosclerophorida demosponge Oscarella lobularis. Because it is the first finding of this organelle in Porifera, the general concepts of the acrosomal evolution are reviewed.

Contribution to the study of egg development and derivation inOscarella lobularis(Porifera, Demospongiae)

Summary Electron-microscope examinations carried out on Oscarella lobularis specimens allowed us to elucidate cytological details of the development of the female gamete. The young oocytes, dispersed in wide areas of the sponge mesohyl, present an eccentric nucleus, microvillar projections and rare pseudopodia. The cytoplasm contains a dense population of microvesicles, vacuoles with amorphous material, glycogen rosettes, and mitochondria which usually appear clustered. During successive stages of development, the oocytes develop longer and more numerous microvilli, and yolk granules become visible. Microvilli can interdigitate with analogous projections protruding from endopinacocytes, thus suggesting that the latter cells may play a role in supplying oocytes with nutrients. Morphological changes of some choanocytes, which were only recorded during the reproductive period, may indicate the transformation of these elements into oogonia.

3‐Lithiopyrroles by Halogen‐Metal Interchange of 3‐Bromo‐1‐(triissopropylsilyl)pyrroles. Synthesis of Verucarin E and Other 3‐Substituted Pyrroles. Preliminary Communication

Abstract3‐Lithio‐1‐(trimethylsilyl)pyrrole (7, Schem 2), obtained by halogen‐metal interchange from the 3‐bromo compound 2, reacted with various electrophilic reagents to provide products, which on fluoride ion desilylation, gave 3‐substituted pyrroles in good overall yields. One such pyrrole 13 (Schem 3), was converted into 2‐formyl‐3‐octadeclpyrrole (14), reputed to be a metabolite of the marine sponge Oscarella lobularis.3,4‐Dibromo‐1‐(triisopropylsityl)pyrrole (5) was efficiently transformed, by a process involving two consecutive bromine‐lithium exchange reactions (Scheme 4), into the antibiotic verrucarin E 17.

Cyclopoida Siphonostoma (Crustacea) von Banyuls (Frankreich, Pyrénées-Orientales) mit Besonderer Berücksichtigung des Gast-Wirtverhältnisses

The sponges, Clathrina clathrus, Cl. lacunosa, Cl. primordialis, and Cl. contorta, as well as Oscarella lobularis, have been checked on the presence of associated siphonostome cyclopoids. Two new species have been found, Asterocheres simplex n. sp. and A. corneliae n. sp. Moreover, the hitherto unknown males of Asterocheres complexus and A. mucronipes have been described. Six species have been found on new hosts, for three species the hitherto unknown host has been discovered (Rhynchomyzon falco on Acontiophorus antennatus Clathrina contorta, on Cl. lacunosa and on Oscarella lobularis, Myzopontius pungens on Cl. primordialis and on Cl. contorta). Furthermore, evidence is provided that certain species of siphonostomes are predominantly found on certain hosts. So, it can be said that Asterocheres simplex frequents Clathrina clathrus and Cl. lacunosa, that Myzopontius pungens frequents Clathrina contorta, and that Asterocheres mucronipes frequents Oscarella lobularis. Asterocheres corneliae is most abundant on Clathrina primordialis, but on the same host one finds also numerous Myzopontius pungens. Finally, a list of all known hosts for siphonostomes is provided, based on an extensive (though certainly not complete) search in the literature.

An Experimental Effect of Light on the Sponge, Oscarella

THE spicule-less sponge, Oscarella lobularis, is an interesting form found on our shores and elsewhere, and presents a wide range of colour variation. Topsent (Arch. de Zool. Exp. et Gen. 3, iii., 1895) has recorded that Oscarella when found exposed fully to light is deep red, as when growing on the stem of the weed Cystoseira or on the sides of rocks, and brownish or even greenish-yellow when growing in dark situations, as on the under side of stones. At Plymouth, a similar range of colour variation is found, while colonies which are overgrowing the under sides of stones and extending over the edges show a development of red colour where the sponge is exposed to direct light.