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Sponges are the most basal metazoan organisms, but they nevertheless already utilize such advanced technologies like light transduction through glas fibers. Many lithoral sponge species are known to harbour photosynthetically active endobionts. Those range from procaryotes to eucaryontic algae. Already 14 years ago this finding raised the question how those endobionts are supplied with light. By implanting light sensitive material into living sponges, we could demonstrate, that the complex spicule structures of the Mediterranean demosponge Tethya aurantium (Pallas, 1766) functions as an effective light harvesting apparatus which transduces light deep inside the sponge tissue. On the other hand, the sympatric but aspicular species Aplysina aerophoba Nardo, 1843 is effectively dark inside. Our results hence for the first time show the in situ function in light transduction of a recently more and more interesting biomaterial, which is unique not only for its mechanical, electrical and optical properties, but especially for its enzymatic production: The sponge spicules.

Freshwater sponges exclusively belong to the suborder Spongillina, which comprises 7 families (Spongillidae, Lubomirskiidae, Malwispongiidae, Metaniidae, Metschnikoviidae, Palaeospongillidae, Potamolepidae) and 45 genera. An increasing number of sampled freshwater sponges cannot be classified unambiguously due to the lack of important morphological characters given in the determination keys commonly used. Given as an example: some Ephydatia species do not build gemmules and thus lack gemmuloscleres which are important characters for their identification which also holds true for many freshwater sponges. Since the first descriptions of freshwater sponges, e.g. Linnaeus 1758, Systema Naturae or Lamarck 1816, their taxonomy and phylogeny are revealed from morphological characters like body size, external shape, consistency, colour, skeletal architecture and scleres (shapes, dimensions and distribution or situation). But depending on the employed marker and method even antithetic results are revealed. Therefore we here discuss the limits and possibilities of already employed and possible markers or better character sets. The synthesis of all possible character sets at a weighted balance produces the most reliable data in taxonomy as well as phylogeny. Such “syntaxonomic” data sets result from morphological matrices as well as DNA-sequence alignments. We compare the resulting phylogenies and evaluate possible molecular markers for taxonomic purposes. For molecular as well as for morphological characters we found some to be not useful (e.g. ITS or colour) and some to be very suitable (e.g. 28S rDNA or scleres) for taxonomic and thus phylogenetic analysis.

Sponges (Porifera) are sessile filter feeders with an enormous filtering capacity and an equally enormous energy consuming throughput resulting in most cases in difficulties in sponge cultivation eg. sufficient nutrient supply. We here show the employment and combination of electron microscopical, light microscopical and molecular biological techniques to approach the function of sponges and their microbial association and their variability during sampling and ex situ cultivation. To have a closer look at sponge associated microbes during cultivation of marine sponges, tissue samples were taken in-situ and during ex situ cultivation. Changes in the bacterial association were correlated to our histological observations and resulting physiology of the sponges eg. secondary metabolites like isofistularin aeroplysinin I and aerophobin I II are measured and do not decrease during ex situ cultivation. Besides transmission electron microscopy (TEM) also paraffin embedding and cryosectioning techniques were applied. In addition, for specific bacterial identification fluorescent in-situ hybridisation (FISH) was used and, for the detection of cyanobacteria their autofluorescence. Additional DAPI staining showed also non autofluorescent bacteria. Transmission electron microscopy identified different bacteria by morphological structures. Combining the data sets resulted, we constructed a three dimensional model of bacterial distribution in sponge tissue and we found a substantially low bacterial load for the in situ condition we investigated. With the different microscopic techniques, especially the optimized fluorescence microscopy, we were able to overcome the main problems like high autofluorescence signal shift and specificity. What is even more, the different methods are controlling themselfes.

Studies of eutardigrades at the specific level face several problems because species are differentiated by few characteristics, which are sometimes difficult to observe. The buccal apparatus with placoids are among the most important characters for species identification. Placoids alternate in position with three equal cuticular apophysis, which are posterior to the end of the buccal tube. The larger anterior placoids, called macroplacoids, are present in either two or three transvers rows. Smaller, posterior placoids are termed microplacoids. Furthermore, size, shape and number of claws are additional important characters which have commonly been used in tardigrade systematics. The buccal apparatus and claws show (after excitation with blue or green light) sufficient auto-fluorescence to be detected at a range of wavelengths (green to red). New techniques for optical sectioning and 3-dimensional reconstruction with increased positional accuracy and spatial resolution allow the reproduction of the real 3D structure of the buccal apparatus. Thus, modern epi-fluorescence techniques provide easy and fast access to important taxonomic features of tardigrades and at the same time produce demonstrative visualizations. We investigated several eutardigrade species with this new methods and displayed the 3- dimensional buccal apparatus and claws for species determination and description. As an outlook: the 3-dimensional image data can be used for the production of spatial models.

Sponges of the family Spongillidae are found around the world in the most different habitats and thus are said to be cosmopolitical species. We investigate two populations of freshwater sponges that at first glance inhabit the very same habitat, a drop off in Lake Constance, Germany. By this example we will demonstrate today`s difficulties in taxonomic work on spongillid sponges and possible outcomes. The upper population built of Spongilla lacustris covers the sandstone drop off from 7 to 14 m water depth ; this species is easy to determine by established taxonomic characters. Beneath 14 m water depth we find a dense population of Ephydatia sp. growing on a dense cover of Dreissena polymorpha. The most intriguing feature of this observation is that both populations are directly adjacent to each other but not overlapping. A very strict borderline is formed at 14 m water depth. There is a strict correlation for the lower population to the presence of Dreissena polymorpha which acts as edificator organism in the observed consortium. As the lower population is built up by a non gemmulating Ephydatia species, macroscopic morphological features as well as molecular data have to be taken into account for the taxonomic description. We, therefore investigated 28S, 18S, ITS and COI Sequences as well as additional morphological and histological characters like canal system and growth form. The combination of the markers we investigated gives a clear hint for the classification as Ephydatia fluviatilis. Our approach is using ecological, morphological and molecular data sets as a synthesis of all available data on the species, thus enables us to uncover it’s taxonomic relationships.

Sponges as so called inner filter feeders are actively producing a current through their bodies thus aspiring food and oxygenated water. Descriptions of anaerobic microbes inhabiting sponge mesohyls have questioned the general assumption of a permanently well-oxygenated sponge tissue. Assumptions of anaerobic processes and anoxic conditions in sponges, however, not only result in implications on biotechnological issues like in vitro culture approaches and nutrient supply. They also suppose a possible regulatory mechanism for sponges to control associated microorganisms by providing an ecologically challenging habitat by changing from aerobic to anaerobic states only allowing adapted organisms to persist within sponges. As various activitiy patterns are already published the pumping activity would allow sponges to actively control not only their inhabitants but also their inhabitants metabolisms by switching from an aerobic to an anaerobic state. Microelectrode measurements on Aplysina aerophoba in the lab showed that this species is well oxygenated when pumping, but when it stops pumping, the major part of the tissue turns anoxic within minutes. We therefore investigated the pumping behaviour of Aplysina aerophoba in situ and present the resulting implications on possible metabolic interactions as well as the biotechnological implications. To address this question in a non-invasive manner we employed SCUBA diving techniques and snorkelling. A tracer was applied in situ to visualize the water current through 2.144 oscules on 259 individual Aplysina at different seasons and different daytimes. Negative effects of the tracer used on the sponges` activity could be excluded by control experiments. All oscules investigated were active and showed a clear tracer discharge. Therefore we deduce a permanent aerobic condition for Aplysina aerophoba tissue in situ. This fits with the detection of betaproteobacterial 16S rRNA genes of the Nitrosospira group and of genes encoding for ammonia monooxygenase (amoA). In contrast, no 16S rRNA genes of anaerobic ammonium oxidizers (anammox) or genes encoding for nitrite reductase (nirK) of denitrifying bacteria could be found in Aplysina aerophoba and associated bacteria.

A strain of Amoeba proteus was isolated from a fresh-water aquarium with tropical fish. The amoebae were identified as A. proteus due to a honey comb structure underneath their nuclear envelope and several other features. Optimal growth of the amebae was observed at 22 C. In the cells two different intracellular bacteria were observed. the bacteria were visible in fixed cells after staining with lacto-aceto orcein or DAPI. One of the bacteria was rod shaped and straight (ro bacteria), whereas the other one was spiral-shaped (sp bacteria). Electron microscopy of thin sectarian revealed a Gram-negative appearance of both bacteria. Ro bacteria appeared to be naked in the host cytoplasm - not encircled by host membranes ; sp bacteria were encircled by two membranes. To get first information about the phylogenetic position of the bacteria fluorescence in situ hybridisation was performed using appropriate oligonucleotide probes. Both bacteria appeared to belong to the Y- subgroup of proteobacteria.