Cytological examination of reduction bodies of Corvomeyenia carolinensis harrison (Porifera: Spongillidae)

Freshwater sponges, Corvomeyenia carolinensis Harrison, were placed into tap water to induce degenerative reduction body formation. Reduction bodies were examined using light and electron microscopy in order to define their histochemical and ultrastructural characteristics. The reduction body of freshwater sponges is an extremely simple developmental system consisting primarily of an archeocyte reserve delimited by a simple squamous pinacoderm. The freshwater sponge reduction body displays many similarities to overwintering phases of marine sponges. The system presents an unusually straightforward vehicle for investigations of degeneration and regeneration as processes in developmental biology and may represent a reasonable vehicle in which to examine the process of the genesis of lysosomes.     

The nature and role of the basal pinacoderm of Corvomeyenia carolinensis Harrison (Porifera: Spongillidae) A histochemical and developmental study

Summary The nature and role of the basal pinacoderm in the freshwater sponge Corvomeyenia carolinensis Harrison was examined using phase contrast microscopy, cytochemistry, and morphogenic analysis of regeneration. The pinacoderm is a nonsyncytial simple squamous epithelium. Pinacocytes, normally nucleolate, contain little histochemically demonstrable RNA, suggesting low levels of protein synthesis. The lack of a major role in food storage is indicated by the slight amount of PAS-positive carbohydrate and the absence of glycogen and acid mucopolysaccharides. Marginal pinacocytes are active in feeding. High levels of acid phosphatase in these cells indicate digestion is following ingestion. Pinacocytes contain numerous contractile vacuoles and play an active role in osmoregulation. These cells play the dominant role in wound healing, becoming actively ameboid to initiate the regenerative process.

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Zusammenfassung Die vorliegende Arbeit is das Resultat von Untersuchungen des Charakters und der Rolle des basalen Pinakoderms im Süsswasserschwamme Corvomeyenia carolinensis Harrison mit Hilfe von Phasenkontrast-Mikroskopie, Cytochemie, und morphogenetischer Analyse der Regenerationsvorgänge. Das Pinakoderm ist ein nicht-syncytielles, einfaches Plattenepithel. Dessen Zellen, die normalerweise nucleoliert sind, enthalten sehr weinig nachweisbares RNA, was eine tiefe Stufe von Proteinsynthese andeutet. Das Fehlen einer bemerkenswerten Rolle dieser Zellen in Hinblick auf Nahrungseinlagerung ist angezeigt durch die kleinen Mengen von POS-positiven Kohlehydraten, als auch durch die Abwesenheit von Glycogen und saueren Mucopolysachariden. Randständige Pinacocyten sind äusserst aktiv in Nahrungsaufnahme. Ein hohes Niveau von sauerer Phosphatase in diesen Zellen beweist dass die Nahrung nach Aufnahme verdaut wird. Die Pinacocyten enthalten zahlreiche kontraktile Vakuolen und spielen eine aktive Rolle in Osmoregulationsvorgängen. Darüber hinaus sind diese Zellen in Wundheilung dominierend beteiligt, nachdem sie sich in aktive amöboide Formen verwandeln, die den Regenerationsprozess durchführen.

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Part of this investigation is based on a portion of a dissertation submitted to the Graduate School of the University of South Carolina in partial fulfillment of the requirements for the degree of Doctor of Philosophy.     

Histology and histochemistry of developing outgrowths of Corvomeyenia carolinensis harrison (Porifera: Spongillidae)

Laboratory-reared outgrowths of the freshwater sponge Corvomeyenia carolinensis Harrison were examined using histological and histochemical techniques, supplemented by phase contrast observations of cellular behavior. The tissue and cellular components of the spongillid outgrowth region were defined in terms of function and morphogenic state. Archeocytes differ considderably, in both histochemical and morphological characteristics, from other cell types of the adult sponge, being histochemically similar to stem cells reported from a variety of developmental series. Archeocytes exhibit cytological characteristics of unspecialized cells capable of high levels of synthetic activity while other cell types of C. carolinensis, for the most part, can be characterized as fully differentiated cells displaying more restricted synthetic capabilities but often accumulating neutral mucoproteins. The presence of aggregates of amebocytes, not identifiable as archeocytes and possibly engaged in gemmule formation, is discussed in terms of current concepts of gemmulation and cellular developmental capabilities in sponges.     

Effects of calcium and salinity on the growth rate of Ephydatia fluviatilis (Porifera: Spongillidae)

The freshwater sponge, Ephydatia fluviatilis (Porifera: Spongillidae), was maintained in a continuous-flow laboratory culture system under several conditions of calcium ion (Ca⁺⁺) concentration and salinity. Experimental results suggest that sponge growth rate increases with increasing Ca⁺⁺ concentration, that sponge growth rate decreases with increasing salinity, and that the negative effect of higher salinity can be overcome by increasing Ca⁺⁺ concentration. The experimental results correlate well with field observations on the effects of salinity and Ca⁺⁺ on the distribution of E. fluviatilis.     

Hatching of freshwater sponge gemmules after low temperature exposure: Ephydatia mülleri (Porifera: Spongillidae)

1. 1.|Gemmules of Ephydatia mülleri can withstand exposure to temperatures down to −80°C for 63 days without loss of hatchability.

2. 2.|Hatching is slowed following exposure to temperatures below −27°C.

3. 3.|There is a slight but significant relationship between gemmule size and the time to hatch.

4. 4.|This species can withstand long-term exposure to winter air temperatures occurring within its known geographic range.

The taxonomic and ecological status of the environmentally restricted spongillid species of North America. III. Corvomeyenia carolinensis Harrison 1971

The viable counts of portions of the microbial communities of the water column of Lake Bonney and associated glacial melt-streams in South Victorialand, Antarctica, were monitored at regular intervals during two consecutive austral summers. Community fluctuations in the water column correlate with the period of input from the meltstream flow into the lake.     

Cold hardiness of the green gemmules of Spongilla lacustris L. (Porifera: Spongillidae)

Most green gemmules of Spongilla lacustris survived enclosure in ice at –20 °C for up to 30 days; however, their rate of germination at 20 °C was less rapid than that of control gemmules. The length of time spent at low temperature had little effect on gemmule survival. In contrast, repeated cooling to –20 °C and warming to 4 °C led to a progressive decline in gemmule viability. These results indicate that cold injury occurs primarily during transitions between high and low temperatures.     

The filtration apparatus for food collection in freshwater sponges (Porifera,Spongillidae)

Summary The freshwater sponges (Spongillidae) feed by filtering out small particles from the water passing through them by means of strainer devices in the flagellated chambers. These are filamentous, fine-meshed structures at the distal ends of the choanocyte collars formed of a mucous material similar to that in the glycocalyx. Each strainer separates its flagellated chamber into an outer and an inner zone. The strainers are an extremely efficient filtering mechanism.     

The metamorphosis of the parenchymula-larva of Ephydatia fluviatilis (Porifera,Spongillidae)

Summary The sexual development of Ephydatia fluviatilis involves a ciliated parenchymula-larva. The mature larva leaves the body of the mother sponge through the excurrent canal system and arrives eventually in the outside world by way of the osculum. At this stage the types of cells found in the adult sponge are already present in the larva. The released larva swims around for a while and then, after a period of between 3 and 48 hours, it attaches, usually with the anterior, larval cavity-bearing pole, onto the substratum. While it is attaching and spreading itself out, the larva undergoes a metamorphosis. The most notable stages of this metamorphosis are as follows: (a) disintegration of the ciliated epithelium from the anterior pole of the larva and its substitution by a pinacocyte epithelium, (b) splitting of the larval cavity and (c) integration of the remains into the developing canal system together with the creation and further development of the organic features of a functioning sponge.     

Oogenesis and larval development of Ephydatia fluviatilis (Porifera,Spongillidae)

Summary In Ephydatia fluviatilis young oocytes already appear in autumn. They pass the winter in the highly reduced sponge, but vitellogenesis and further development do not take place before following spring. The fact that the young oocytes appear before the normal period of reproduction makes E. fluviatilis different from all other local freshwater sponges, which reduce totally in autumn. E. fluviatilis seems to be a gonochorist. The oocytes originate from archaeocytes and during the first growth phase they reach a diameter of approximately 40 m. In the second growth phase the oocyte is enclosed in a single-layered follicle epithelium and grows to 170–180 m by phagocytosis of trophocytes. The fully developed egg cell finally shows a distinct layering of the incorporated yolk material. Cleavage is totally equal to unequal so that macro- and micromeres appear in some cleavage stages. Cleavage leads to a solid embryo consisting of uniform cells. At this stage of development the first scleroblasts appear. As the cells develop they are surrounded by companion cells, managing the transport of the scleroblasts. The further development to the larva is marked by the appearance of the larval cavity, typical for larvae of Spongillids, which finally occupies about half the volume of the larva at emergence. The periphery of the larva consists of a single-layered ciliated epithelium. After emergence the larva forms flagellated chambers, which are integrated into the primordia of the excurrent canal system. This system connects with the larval cavity and ensures that it becomes part of the excurrent canal system of the young sponge. Particularly in the region of the larval cavity the ciliated epithelium of the free larva is reduced. Here a new larval surface epithelium is formed by pinacocytes.     

Canal systems and choanocyte chambers in freshwater sponges (Porifera,Spongillidae)

Summary The spongillid species Spongilla lacustris and Ephydatia fluviatilis possess choanocyte chambers of the classical eurypylous type. They are surrounded by the mesenchymal tissue and connected to the incurrent canal system by prosopyles and to the excurrent canal system by wide apopyles. Each apopyle is sealed against spaces between the basal choanocyte collar parts by a ring of uniflagellated cone cells. The functional aspects of the choanocyte chamber and canal structure are discussed.Dedicated to Prof. Dr. K.E. Wohlfarth-Bottermann, Bonn, in honor of his 65th birthday     

Revision of the genus Clathrina (Porifera, Calcarea)

The genus Clathrina has one of the most difficult systematic arrangements in the Porifera, Class Calcarea. Few morphological characters can be used to describe its species, and the systematics and the geographical distribution of its species have changed several times, according to the point of view of the systematists. 'Lumpers' consider that clathrinas are morphologically plastic, while 'splitters' believe that even slight morphological differences should be considered sufficient to distinguish between species. The morphology of several specimens/species of Clathrina , including the type species, when possible, was studied and used to produce the first revision of this genus. Using results obtained from previous morphological and molecular studies, the morphological characters were chosen and analysed in all studied specimens. In total, 43 species were found, nine of which are new to science. These results agree with the viewpoint that morphological characters such as type and distribution of spicules, size of actines, spines, anastomosis of the cormus, organization of the osculum and presence of granules in cells, are useful when establishing the taxonomy of the genus.  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society , 2003, 139 , 1−62.     

Speciation in the White-breasted Nuthatch (Sitta carolinensis): a multilocus perspective

Inferring the evolutionary and ecological processes that have shaped contemporary species distributions using the geographic distribution of gene lineages is the principal goal of phylogeographic research. Researchers in the field have recognized that inferences made from a single gene, often mitochondrial, can be informative regarding the pattern of diversification but lack conclusive information regarding the evolutionary mechanisms that led to the observed patterns. Here, we use a multilocus (20 loci) data set to explore the evolutionary history of the White‐breasted Nuthatch (Sitta carolinensis). A previous single‐locus study found S. carolinensis is comprised of four reciprocally monophyletic clades geographically restricted to the pine and oak forests of: (i) eastern North America, (ii) southern Rocky Mountain and Mexican Mountain ranges, (iii) Eastern Sierra Nevada and Northern Rocky Mountains and (iv) Pacific slope of North America. The diversification of the clades was attributed to the fragmentation of North American pine and oak woodlands in the Pliocene with subsequent divergences owing to the Pleistocene glacial cycles. Principal component, clustering and species tree analyses of the multilocus data resolved the same four groups or lineages found in the single‐locus study. Coalescent analyses and hypothesis testing of nested isolation and migration models indicate that isolation and not gene flow has been the major evolutionary mechanism responsible for shaping genetic variation, and all the divergence events within S. carolinensis have occurred in response to the Pleistocene glacial cycles.     

Phase contrast photomicrography of cellular behaviour in spongillid porocytes (Porifera: Spongillidae)

The combination of phase contrast photomicrography with a method for phase contrast observation of living sponges facilitated the initial photographic record of spongillid porocyte cellular behavior. Porocytes ofCorvomeyenia carolinensis Harrison (Spongillidae) exhibit true intracellular pores and are components of the incurrent system. The number of porocyte contractile vacuoles increases during pore dilation. This increase is possibly related to an increase in the amount of cell surface in contact with the hypotonic aqueous environment. The porocyte cell type appears closely related to, and is likely derived morphogenetically from, pinacocytes of the upper pinacoderm.     

Life cycle of Spongilla lacustris (Porifera,Spongillidae): a cue for environment-dependent phenotype

We studied the life cycle and growth of Spongilla lacustris in a stream with three distinct habitats. Sponge populations in the habitats exhibited different adaptive strategies. Growth forms of S. lacustris ranged from encrusting to digitate and branched. Environmental factors controlled the appearance of each growth form. In the most hospitable habitat, a variety of colonization strategies and different growth forms were present. In the less hospitable habitat growth was restricted to small and encrusting specimens. In the optimal habitat, the largest and most luxuriant specimens developed. Gemmulation and hatching were dephased among specimens in the three habitats; hence gemmules were present for long periods of time. S. lacustris was found capable of displaying two life strategies: r in the short run, K in the long run.     

Ultrastructural investigation of spermatogenesis in Spongilla lacustris and Ephydatia fluviatilis (Porifera,Spongillidae)

Summary Spermatogenesis of the spongillids investigated here is similar in Spongilla lacustris and Ephydatia fluviatilis and proceeds, on the whole, as in other Eumetazoa. Sponges however lack true sex organs, the germ cells developing from somatic cells. The male germ cells originate in spongillids from choanocytes and the female ones from archaeocytes. In Spongilla lacustris single choanocytes leave the flagellated chambers and transform into spermatogonia; in Ephydatia fluviatilis they result from differential cell division. The spermatogonia gather in distinct mesenchyme regions and are surrounded by cyst-building cells. Thus spermatocysts are built in which spermatogenesis proceeds. The spermatogonia in the spermatocysts differentiate into flagellated spermatocytes of I. order. In this process, the early appearance of the flagellum and its mode of formation are uncommon. The following meiotic divisions generate spermatocytes of II. order in the first step and spermatids in the second. In both developmental stages the cells remain connected by cytoplasmic bridges. In the subsequent spermiocytogenesis the cytoplasm of the spermatids is reduced. The reduced parts of the cytoplasm appear as cell fragments in the lumen of the spermatocysts and are eventually ingested by the cystwall cells. The mature spermatozoa arrange in the spermatocysts in a characteristic pattern. Later the spermatocysts open into the excurrent canal system and the spermatozoa leave the sponge with the egestive water stream.     

Cytochemical Observations of Gemmule Development in Eunapius fragilis (Leidy): Porifera; Spongillidae

The cytology and cytochemistry of gemule formation in the freshwater sponge Eunapius fragilis (Leidy) is investigated. The aggregation of ameboid cells which initiates gemmulation is composed of three distinct cell types, two of these fitting the morphological criteria of the archeocyte class. The third cell type, the granular cell, is a differentiated cell type which undergoes cytolysis during gem-mule coat synthesis. Following early polarisation of the aggregate into an internal reproductive area and a peripheral coat region, a structurally and chemically heterogeneous gemmule coat is synthesis-ed. The coat is formed through secretory activities involving several cell types including, possibly, the internal endothelium. The coat is composed of "collagenous" fibers embedded in a matrix of varying degrees of density–showing close structural and cytochemical similarities to vertebrate chondroid tissue. Vitelline platelets of thesocytes of E. fragilis do not cytochemically resemble any previously reported vitelline inclusions from other sponges. Outer valves of the platelets contain components stained by basic dyes at acidic pH which are not extracted by RNase. Distinct differences in developmental processes and morphological–including cytochemical–characteristics of gemmules of different spongillid species are apparent.     

Microscopical aspects on symbiosis of Spongilla lacustris (Porifera,Spongillidae) and green algae

Summary When growing in the sunlight, some specimens of Spongilla lacustris are coloured green due to the presence of symbiotic unicellular chlorellae. The algae live inside most sponge cells. The chlorellae were extracted from green sponges, cultivated, added to algae-free sponges and fixed after different incubation times. In this way the uptake of the algae, their distribution and their final whereabouts in the mesenchymatic cells could be followed by in vivo microscopy, phase-contrast microscopy and electron microscopy. A few minutes after addition, the chlorellae can be found inside the choanocyte chambers. Here they are taken up by the cell bodies and collars of the choanocytes. Pinacocytes are also involved in the uptake. The distribution of algae results from a specific transmission from the donor cell to the receiver cell. The chlorellae are not released from their host vacuoles until they are extensively enclosed by the cell taking them up. Six hours after addition, all sponge cells contain algae except granulocytes, microscleroblasts, the pinacocytes of the peripheral rim region and those of the pinacoderm. The chlorellae are able to divide inside the sponge cells.Abbreviations StM Stereo-microscopical photograph - PhC Phase-contrast microscopical photograph - EM Electron microscopical photograph