Freshwater Sponge Ephydatia Fluviatilis Research Articles

Electron microscope study of an intranuclear protozoan parasite in archaeocytes of the fresh water sponge Ephydatia fluviatilis L. (Porifera)

An intranuclear protozoan parasite in archaeocytes of the fresh water sponge Ephydatia fluviatilis is described. The parasites only attack the archaeocytes of this spongillid, invade their cytoplasm and later enter the nucleus. In the further development the parasite grows and undergoes nuclear divisions leading to a plasmodium with 30–40 nuclei. The parasite gradually displaces the host cell nucleus, which eventually becomes restricted to a small peripheral band surrounding the growing parasite. The following developmental phase may be considered as “formation of spores” or “sporulation”. The body of the parasite (“sporont”) undergoes fragmentation into lobes containing one to several nuclei, leading to the formation of spore-like structures (“spores”). Differentiated “spores” are limited by two membranes and contain a small nucleus, endoplasmic reticulum, and mitochondria-like structures. The completely differentiated spores invade new archaeocytes. The parasite kills the sponge about three months after invasion. Die Parasiten wurden in den Archäocyten von Ephydatia fluviatilis vorgefunden. Sie dringen in ihr Cytoplasma, später in ihren Kern ein, wachsen heran und machen Kernteilungen durch, die zu einem Plasmodium mit 30 bis 40 Zellkernen führen. Hierbei verdrängen die Parasiten den Innenraum des Wirtszellkerns bis auf einen schmalen, peripheren Bereich rings um den Parasiten. Die anschließende Entwicklungsphase kann als Sporenbildung (Sporulation) bezeichnet werden. Hierbei führt die Fragmentierung des Parasiten-Zellkörpers zu „Sporen“. Ausdifferenzierte „Sporen“ weisen 2 Membranen auf und enthalten einen kleinen Zellkern, ein endoplasmatisches Retikulum und mitochondrien-ähnliche Strukturen. Fertige Sporen dringen erneut in Archäocyten ein. Die Parasiten töten den Schwamm etwa 3 Monate nach Befall.

Effect of Bacterial Concentration on Retention and Growth Rate of the Freshwater Sponge Ephydatia fluviatilis

Using 1-h pulse of radioactively labeled Escherichia coli, we examined, during a 24-h period, the feeding activities of Ephydatia fluviatilis in the presence of different bacterial concentrations. The results indicate an influence of the nutritional state of the sponge and the existence of a steady optimal retention rate value related to the maximal rate of phagocytosis and digestion of the sponge. These results are consistent with the measurements of sponge growth showing that bacteria can fulfill the entire food requirements of E. fluviatilis and sustain high rates of growth. The pattern of retention in relation to the bacterial concentration and nutritional state of the sponge is discussed.

Topsentins, new toxic bis-indole alkaloids from the marine sponge Topsentiagenitrix

Three new bis-indole alkaloids, topsentin-A (1), -B1 (2), and -B2 (3) have been isolated from the Mediterranean sponge Topsentiagenitrix and their structure determined by spectroscopic methods. These compounds are weakly toxic for fish and for dissociated cells of the freshwater sponge Ephydatiafluviatilis and thus might be partially responsible for the chemical defense of the sponge.

A Quantitative Study of the Retention of Radioactively Labeled E. coli by the Freshwater Sponge Ephydatia fluviatilis

In this method designed to quantify the amount of bacteria retained by sponges, young Ephydatia fluviatilis raised in vitro were provided with E. coli grown in the presence of ³H-labeled thymidine. The maximal retention capacity was reached after 15-24 h and was followed by a loss of radioactivity at a steady rate. The nonspecific adhesion of bacteria to the substratum remained close to 10% for 15 h and increased to as much as 43% by 24-48 h. Sponges provided repeatedly with bacteria showed a higher retention capacity, suggesting the efficiency of the bacterial nutrition. Transmission electron microscopy and scanning electron microscopy showed that, after a preliminary adhesion to the choanocytes and exopinacocytes, bacteria were engulfed in individual phagosomes, which later fused together. The quantitative method established in this paper should prove useful for further studies of the retention of any particulate matter by sponges.

The spermatogenesis of Ephydatia fluviatilis (Porifera)

Spermatogensis of the freshwater sponge Ephydatia fluviatilis begins with differential mitosis of choanocytes in the flagellated chambers. The spermatogonia thus produced aggregate in the mesenchyme by amoeboid movement. They are surrounded by dendritic cells which eventually form the walls of spermatocysts, within which spermatogenesis takes place. Notable features are the early formation of flagella in first order spermatocytes and the appearance of two flagella in the metaphase of the second maturation division.

Allogeneic recognition in sponges: Development, structure, and nature of the nonmerging front in Ephydatia fluviatilis.

Whenever individuals of the freshwater sponge Ephydatia fluviatilis belonging to different strains come into contact, they reject each other by building a nonmerging front. The present work describes the development, the structure, and the nature of the barrier secreted between two individuals. The observations reported give unequivocal data about the collagen nature of the incompatibility barrier. First, ultrastructural investigations reveal the presence of fibrils and microfibrils which are, respectively, typical of collagen and spongin. Second, incorporation of tritiated proline, a characteristic precursor of collagen and related products, is particularly intense in the front. The involvement of several cell types in the barrier formation is discussed. The allogeneic incompatibility reaction between E. fluviatilis individuals appears very close to the process of allograft chronic rejection that we formerly described for some marine sponges. Both phenomena are basically analogous to the process which fixes to and isolates the sponges from their substrate.

Water temperature: A factor in the seasonality of two freshwater sponge species, Ephydatia fluviatilis and Spongilla alba

Two freshwater sponge species, Ephvdatia fluviatilis and Spongilla alba, were maintained in a continuous-flow laboratory culture system at several different water temperatures. Experimental results suggest that sponge growth rate is affected by water temperature and that it is affected differently in the two species. The results correlate well with field observations on species abundance at different water temperatures and thereby support the view that water temperature is a factor determining seasonality in these species.

Endocytosis of latex beads by the exopinacoderm in the fresh water sponge Ephydatia fluviatilis: An in vitro and in situ study in SEM and TEM

Endocytosis capability of the dermal membrane of Ephydatia fluviatilis has been demonstrated in vitro and in situ using two different sizes of calibrated Latex beads. After a preliminary adhesion to the cell coat, 5.7- and 0.109-μm beads were endocytized by exopinacocytes. Some ingestion mechanisms appeared to depend upon particle size. In vitro, with 0.109-μm beads, the exopinacocyte cell surface creased, forming ruffles in the central area of the cells. In vitro and in situ, 0.109-μm beads were observed to slip through gaps in the dermal membrane. In addition to their conventional role as an inhalent pore, porocytes were shown to possess a particle retention ability, which remained even in the case of complete closure of the ostia. Endocytosis, occuring on the whole sponge surface, points out the importance of exopinacocytes in particle retention, bypassing the choanocytes in their capture role.

Nutrient translocation from green algal symbionts to the freshwater sponge Ephydatia fluviatilis

The symbiosis between the freshwater sponge Ephydatia fluviatilis and a chlorella-like green alga is not obligate and only occurs when the sponge grows in the light. The algae accumulate intracellular pools of sucrose and glucose and translocate between 9 and 17% of the total photosynthate to the host. The principal product translocated is glucose which is fed directly into the sponge metabolic pool. White sponges transplanted back into the river in the shade grew logarithmically with a mean doubling time of 12 days. Sponges transplanted into illuminated habitats did not grow. It is unknown how the sponge acquires its algal symbiont.

Isolation of a highly pure archeocyte fraction from the fresh-water spongeEphydatia fluviatilis.

A pure archeocyte fraction was isolated from the fresh-water spongeEphydatia fluviatilis by density gradient centrifugation of dissociated cell suspensions. The nature and purity of the fraction were confirmed by electron microscopy.

Aggregative properties of different cell types of the fresh-water spongeEphydatia fluviatilis isolated on ficoll gradients.

Cell suspensions of the fresh-watersponge Ephydatia fluviatilis have been fractionated by means ofFicoll gradient centrifugation. Three fractions were isolated. The densest contains archeocyte-like cells only; the intermediate fraction is very rich in choanocytes, and the lightest is a mixture of cell types. Earch fraction shows specificaggregative properties and potentialities to reconstitute functional sponges.It appears that the sequence of reconstitution events can be selectively altered by certain disequilibria in the cell populationThese preliminary results constitute a first approach to the analysis ofcell type specificity in sponges.

An experimental study of the life-cycle of the fresh-water spongeEphydatia fluvitilis in its natural surroundings

The life cycle of three strains of the fresh-water spongeEphydatia fluviatilis, experimentally cultivated in a pond near Brussels has been studied.The complete experiment lasted four consecutive years.Seasonal histological fluctuations are described. They emphasise that this species overwinters in a highly disorganized stage and completely regenerates in the early spring.These observations constitute a first approach to the analysis of the induction mechanisms of sexual reproduction.They clearly indicate the necessity for the sponge to overwinter in the field, in order to be able to undergo a sexual reproduction. It is to be noted that the first oocytes appear every year at the beginning of the winter, a little while after the sponges have reached their typical disorganized stage.The stability of the strain throughout sexual reproduction is demonstrated.

Mise en evidence du caractere photo-sensible de la respiration des gemmules de spongillidae (Porifera)

1. 1. The oxygen consumption of gemmules of the fresh-water sponge Ephydatia fluviatilis (Porifera, Spongillidae) has been measured with a Warburg respirometer, during a 70-hr incubation at 20°C. 2. 2. In daylight, and in an artificial light-cycle as well, the oxygen consumption has been shown to depend on illumination. The QO 2 in the dark amounts to 50–70 per cent of its value in the light. 3. 3. The R.Q.'s of the incubated gemmules are low; they also show a wide difference between light and dark values, ranging around 0·4 in the former condition and 0·1 in the latter. 4. 4. No hypothesis can presently be proposed to explain these phenomena.