Tapping the archives: the sterol composition of marine sponge species, as determined non-invasively from museum-preserved specimens, reveals biogeographical features.

Over 8600 species are currently recorded in the phylum Porifera (sponges). They produce a large diversity of biochemical compounds including sterols, with more than 250 different sterols identified. Some of these sterols are of great interest, due to their use for fingerprinting in ecological and biomarker (molecular fossil) studies. As a large number of identified extant species from biodiversity surveys are housed in museum collections, preserved in ethanol, these present a potentially rich source of identified specimens for comparative lipid analyses. Here, we show that, in at least one species, sterol distributions obtained from the ethanol used to preserve specimens of sponges were representative, and comparable to the sterol distribution obtained from wet-frozen and from freeze-dried tissue from the same species. We employed both GC-MS and two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS), with an improved signal-to-noise ratio for even minor constituents. Analysis of two additional specimens of the same species, but of different provenance, resulted in detection of marked differences in sterol composition, which could be attributed to variations in geography, environmental conditions, microbial communities, diet or cryptic speciation. The possibility of using ethanol from identified, preserved museum sponges could drastically increase the number of available samples. This could enable the study of their sterol complements, and the detailed investigation of differences due to geographical and oceanographic, phylogenetic, and other factors in unprecedented detail.

Combining morphometrics with molecular taxonomy: how different are similar foliose keratose sponges from the Australian tropics?

Sponge taxonomy can be challenging as many groups exhibit extreme morphological plasticity induced by local environmental conditions. Foliose keratose sponges of the sub-family Phyllospongiinae (Dictyoceratida, Thorectidae: Strepsichordaia, Phyllospongia and Carteriospongia) are commonly found in intertidal and subtidal habitats of the Indo-Pacific. Lacking spicules, these sponges can be difficult to differentiate due to the lack of reliable morphological characters for species delineation. We use molecular phylogenies inferred from the nuclear Internal Transcribed Spacer 2 region (ITS2) and morphometrics (19 characters; 52 character states) to identify evolutionarily significant units (ESUs; sensu Moritz) within foliose Phyllosponginiids collected from seven geographic locations across tropical eastern and Western Australia. The ITS2 topology was congruent with the tree derived from Bayesian inference of discrete morphological characters supporting expected taxonomic relationships at the genus level and the identification of five ESUs. However, phylogenies inferred from the ITS2 marker revealed multiple sequence clusters, some of which were characterised by distinct morphological features and specific geographic ranges. Our results are discussed in light of taxonomic incongruences within this study, hidden sponge diversity and the role of vicariant events in influencing present day distribution patterns.

The biogeography and phylogeny of unicellular cyanobacterial symbionts in sponges from Australia and the Mediterranean.

The distribution, host associations, and phylogenetic relationships of the unicellular cyanobacterial symbionts of selected marine sponges were investigated with direct 16s rDNA sequencing. The results indicate that the symbionts of the marine sponges Aplysina aerophoba, Ircinia variabilis, and Petrosia ficiformis from the Mediterranean, four Chondrilla species from Australia and the Mediterranean, and Haliclona sp. from Australia support a diversity of symbionts comprising at least four closely related species of Synechococcus. These include the symbionts presently described as Aphanocapsa feldmannii from P. ficiformis and Chondrilla nucula. A fifth symbiont from Cymbastela marshae in Australia is an undescribed symbiont of sponges, related to Oscillatoria rosea. One symbiont, Candidatus Synechococcus spongiarum, was found in diverse sponge genera in the Mediterranean Sea and the Indian, Pacific, and Southern oceans, whereas others were apparently more restricted in host association and distribution. These results are discussed in terms of the biodiversity and biogeographic distributions of cyanobacterial symbionts.

Control of Vascular Sap pH by the Vessel-Associated Cells in Woody Species (Physiological and Immunological Studies).

In Robinia wood, the vessel-associated cells form a continuous sleeve around the vessels. Variations in pH of the solution perfused through the vessels during the annual cycle and the opposing effects of carbonyl cyanide-m-chlorophenylhydrazone and fusicoccin on this pH value indicate that some living cells of the wood are involved in the control of vascular sap pH and that this control fluctuates with the seasons. The immunolocalization of the plasma membrane HT+-ATPase in Robinia wood was studied by the immunogold-silver-staining technique using an antibody raised against a conserved stretch of the cytoplasmic domain of the H+-ATPase. The immunostaining is much stronger in vessel-associated cells than in other living cell types (ray and axial parenchyma elements) of the secondary xylem. Our data show an efficient involvement of this cell type in the control of vascular sap pH.

Immunolocalization of the Plasma Membrane H+ -ATPase in Minor Veins of Vicia faba in Relation to Phloem Loading.

The immunolocalization of the plasma membrane H+ -ATPase, which generates a proton motive force energizing the uptake of inorganic and organic solutes, was studied by electron microscopy. The cells studied were in minor veins of Vicia faba L. exporting leaves, where photosynthates are supposed to be absorbed from the apoplast by phloem transfer cells. Immunologically detectable H+ -ATPase varied among the different cell types and was considerably denser in the transfer cells than in the other cell types, particularly in the sieve tube. Moreover, the distribution of the H+ -ATPase was not homogeneous in transfer cells, that pump being more concentrated in the region adjacent to the bundle sheath, phloem parenchyma, and xylem vessels than along the smooth part of the wall bordering the sieve tube. These results show that the plasma membrane infoldings of transfer cells possess the proton-pumping machinery required to energize an efficient uptake of photosynthates from the phloem apoplast and an efficient retrieval of nitrogenous compounds from the vascular sap.