SEM-EDS and X-ray micro computed tomography studies of skeletal surface pattern and body structure in the freshwater sponge Spongilla lacustris collected from Goczalkowice reservoir habit (Southern Poland)

Abstract

Introduction. Freshwater sponges are common animals of most aquatic ecosystems. They feed by filtering small particles from the water, and so are thought to be sensitive indicators of pollution. Sponges are strongly associated with the abiotic environment and are therefore used as bioindicators for monitoring of water quality in water habitats. Among the freshwater sponges, Spongilla lacustris is one of the classic models used to study evolution, gene regulation, development, physiology and structural biology in animal water systems. It is also important in diagnostic of aquatic environments. The aim of this study was to characterize and visualize three-dimensional architecture of sponge body and measure skeleton elements of S. lacustris from Goczalkowice reservoir for identification purposes. Material and methods. The scanning electron microscopy with an energy dispersive X-ray microanalysis (SEM--EDS) and X-ray micro computed tomography (micro-CT) were used to provide non-invasive visualization of the three-dimensional architecture of Spongilla lacustris body. Results. We showed that sponge skeleton was not homogeneous in composition and comprised several forms of skeleton organization. Ectosomal skeleton occurred as spicular brushes at apices of primary fibres with cementing spongin material. Choanosomal skeletal architecture was alveolate with pauci-to multispicular primary fibres connected by paucispicular transverse fibres, made by megascleres embedded in a scanty spongin matrix both in the choanosome and at the sponge surface. In contrast, microscleres were irregularly scattered in choanosome and skeletal surface. Furthermore, SEM-EDS studies showed that the distribution of silica in megascleres and microscleres was observed along the spicules and sponge surface areas. Conclusions. In conclusion, we showed that the combination of SEM-EDS and micro-CT microscopy techniques allowed obtaining a complete picture of the sponge spatial architecture. SEM-EDS and X-ray micro-CT studies of freshwater sponge

Combined complementary imaging techniques in morphological analysis of Spongilla lacustris (Linnaeus 1759)

“…Sponge identification was made on the basis of morphology of megascleres (smooth and straight, slightly curved) and microscleres (entirely covered with small spines) (Simm 1953; Lopp et al 2007). A fragment of about 100 cm 2 of the fresh sponge was manually collected in June and then immediately placed in containers with water from the reservoir (Karcz et al 2015). Sponge bodies were dissected (Fig.…”

“…Identification of the elemental composition of the samples was performed with the use of the Hitachi SU8010 field emission scanning electron microscope with a Thermo Scientific Noran System 7 energy‐dispersive spectrometer (Thermo Fisher Scientific) as described in the previous paper (Karcz et al 2015). For the analysis of the background and element‐specific peak spectra, the NSS3 X‐ray Microanalysis software (Thermo Fisher Scientific) was used.…”

“…The size, morphology, and spatial organization of these structures determine sponges' physiology. Arrangement and morphology of constructive elements, made of composites, may be characterized utilizing sophisticated and precise methods (Karcz et al 2015). The X‐ray tomography methods allow direct visualization and reconstruction of three‐dimensional (3D) structures of the sponge body (Nickel et al 2008).…”

“…The scaffold is filled with mesohyl containing elements of siliceous spicule that protrude from the sponge surface (ectosomal skeleton). Moreover, it is possible to recognize numerous spherical gemmules (200–400 μ m in diameter) dispersed within the sponge body (Karcz et al 2015). However, one should note that it is not clear how the various structural elements are arranged in space to form S. lacustris skeleton.…”

Impact of an Engineered Copper-Titanium Dioxide Nanocomposite and Parent Substrates on the Bacteria Viability, Antioxidant Enzymes and Fatty Acid Profiling

“…To evaluate the size and morphology of the bacterial cells, they were visualized before and after treatment using scanning electron microscopy (SEM), in accordance with the methodology of Karcz et al [58]. The cell surface mapping and interaction of the bacterial membrane, with visualized NMs at the microstructural level, were analysed using energy dispersive X-ray spectrometry (EDS).…”