The Largest Bio-Silica Structure on Earth: The Giant Basal Spicule from the Deep-Sea Glass Sponge Monorhaphis chuni
Figure 7
NanoSIMS images taken from a sublamella of the GBS. (A) Polished cross section through a GBS showing the three morphological regions within a spicule, the central axial canal (ac), the surrounding axial cylinder (cy), and the lamellar region (la). Light microscopic image. (B) Schematic illustration of the cross section through the GBS outlining the growth of the spicules with emphasis on the outlining the axial cylinder (cy) of which lamellae have been “biosintered”. The measurements have been performed in the boxed area. The axial cylinder surrounds the axial filament (af). (C) NanoSIMS analyses. (C-a) Image taken simultaneously with the NanoSIMS by secondary electrons; the sublamella is marked (sla) and has a thickness of 5 μm. (C-b to C-e) NanoSIMS mapping to determine the distributions of 12C, 28Si, 18O, and 32S. (C-b) The pseudocolor image reflects the changes of the 12C/28Si-ratio along the indicated line field. Below: the 12C concentrations are calculated based on the 12C/28Si-ratio and applying the relative sensitivity factors. (C-c) 16O/28Si-ratio shows the homogeneity of the “biological glass” within the lamellae. The absolute ratio is caused by the difference of the ionization probability of silicon and oxygen in this matrix. Mapping of (C-d) silicon; the total counts of 28Si are given, and of (C-e) sulfur and silicon; the 32S/28Si ratios are computed. Either (absolute) concentrations or the ratio of concentrations are given as pseudocolor images. Different colors correspond to different intensities of signal or ratio, increasing from black to red. Below the color images the corresponding line-scan data are given. In (C-a), (C-b), and (C-c), the hierarchical composition of one 5 μm sublamella (sla; double-headed arrow; bordered by red arrows) from three slats (s; framed by green arrows), displaying widths of about 1.5 to 1.8 mm each, is indicated. (D) and (E) Light and SEM microscopical images showing the location of the axial cylinder (cy).
