BackgroundPhotosynthetic sponges are important components of reef ecosystems around the world, but are poorly understood. It is often assumed that temperate regions have low diversity and abundance of photosynthetic sponges, but to date no studies have investigated this question. The aim of this study was to compare the percentages of photosynthetic sponges in temperate Western Australia (WA) with previously published data on tropical regions, and to determine the abundance and diversity of these associations in a range of temperate environments.ResultsWe sampled sponges on 5 m belt transects to determine the percentage of photosynthetic sponges and identified at least one representative of each group of symbionts using 16S rDNA sequencing together with microscopy techniques. Our results demonstrate that photosynthetic sponges are abundant in temperate WA, with an average of 63% of sponge individuals hosting high levels of photosynthetic symbionts and 11% with low to medium levels. These percentages of photosynthetic sponges are comparable to those found on tropical reefs and may have important implications for ecosystem function on temperate reefs in other areas of the world. A diverse range of symbionts sometimes occurred within a small geographic area, including the three "big" cyanobacterial clades, Oscillatoria spongeliae, "Candidatus Synechococcus spongiarum" and Synechocystis species, and it appears that these clades all occur in a wide range of sponges. Additionally, spongin-permeating red algae occurred in at least 7 sponge species. This study provides the first investigation of the molecular phylogeny of rhodophyte symbionts in sponges.ConclusionPhotosynthetic sponges are abundant and diverse in temperate WA, with comparable percentages of photosynthetic to non-photosynthetic sponges to tropical zones. It appears that there are three common generalist clades of cyanobacterial symbionts of sponges which occur in a wide range of sponges in a wide range of environmental conditions.

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The present work is the first one presenting life-history information of bisexual tardigrades under laboratory conditions. Two bisexual tardigrade strains (Paramacrobiotus tonollii and Macrobiotus sapiens) were examined analysing the following life-history traits: active life span, body lengths, age at first oviposition, egg-laying intervals, clutch size, hatching time and hatching percentages. Comparing parthenogenetic and bisexual tardigrades, our results demonstrate that life-history traits did not correlate to a mode of reproduction but rather vary in between the different species. Differences were observed for embryonic development (P. tonollii: 16 days; M. sapiens: 12 days), for body lengths (P. tonollii larger than M. sapiens) and for a longer life span of M. sapiens (about 83 days).

Proteins regulate diverse biological processes by the specific interaction with, e.g., nucleic acids, proteins and inorganic molecules. The generation of inorganic hybrid materials, such as shell formation in mollusks, is a protein-controlled mineralization process. Moreover, inorganic-binding peptides are attractive for the bioinspired mineralization of non-natural inorganic functional materials for technical applications. However, it is still challenging to identify mineral-binding peptide motifs from biological systems as well as for technical systems. Here, three complementary approaches were combined to analyze protein motifs consisting of alternating positively and negatively charged amino acids: (i) the screening of natural biomineralization proteins; (ii) the selection of inorganic-binding peptides derived from phage display; and (iii) the mineralization of tobacco mosaic virus (TMV)-based templates. A respective peptide motif displayed on the TMV surface had a major impact on the SiO2 mineralization. In addition, similar motifs were found in zinc oxide- and zirconia-binding peptides indicating a general binding feature. The comparative analysis presented here raises new questions regarding whether or not there is a common design principle based on acidic and basic amino acids for peptides interacting with minerals.

Silver nanoparticles (AgNPs) are one of the most important nanomaterials for toxicological study due to their extensive use in consumer products and their potential effects on both human and animal health, and the environment. There is, however, insufficient information on their impact on the marine environment. Here, we study the effect of AgNPs in sea urchin (Paracentrotus lividus) development by X-ray absorption near edge structure (XANES) and Fourier transform infrared (FTIR) spectroscopy. Agglomerated AgNPs were observed in sea urchin larva at 51 h after exposure to AgNPs with a concentration of 0.3 mg/L. XANES shows that agglomerated AgNPs contain oxidized Ag species complexed with S and O/N ligands. FTIR results confirm the presence of additional sulphur compounds suggestive of a biological response to the toxicity of AgNPs in the sea urchins. Additionally, it could be concluded from the FTIR results that there is a loss of calcite in the sea urchins exposed to AgNPs.

In the protist world, the ciliate Coleps hirtus (phylum Ciliophora, class Prostomatea) synthesizes a peculiar biomineralized test made of alveolar plates, structures located within alveolar vesicles at the cell cortex. Alveolar plates are arranged by overlapping like an armor and they are thought to protect and/or stiffen the cell. Although their morphology is species-specific and of complex architecture, so far almost nothing is known about their genesis, their structure and their elemental and mineral composition. We investigated the genesis of new alveolar plates after cell division and examined cells and isolated alveolar plates by electron microscopy, energy-dispersive X-ray spectroscopy, FTIR and X-ray diffraction. Our investigations revealed an organic mesh-like structure that guides the formation of new alveolar plates like a template and the role of vesicles transporting inorganic material. We further demonstrated that the inorganic part of the alveolar plates is composed out of amorphous calcium carbonate. For stabilization of the amorphous phase, the alveolar vesicles, the organic fraction and the element phosphorus may play a role.

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