Bavestrello Giorgio, Benatti Umberto, Cattaneo-Vietti Riccardo, Cerrano Carlo, Giovine Marco
Dipartimento di Scienze del Mare, Università Politecnica di Ancona, I-60131 Ancona, Italy.
Microsc Res Tech. 2003 Nov 1;62(4):327-35. doi: 10.1002/jemt.10399.
Several sponge species incorporate a wide range of foreign material. Whether such material is actively selected by the sponge is controversial. Here we compare the available suspended matter and the sediment incorporated in the tissue of the demosponge Chondrosia reniformis. Field observations and laboratory experiments indicate that this species selects and incorporates only siliceous materials, in particular quartz particles and opal sponge spicules, avoiding carbonate particles. The reaction of ectosome cells of Chondrosia depends on the forms of silica: after settlement of crystalline quartz particles on the sponge surface, the pinacocytes contract uniformly, giving rise to a ruffled surface that remains throughout the incorporation of foreign material. In contrast, the opal spicules elicit a motile response in pinacocytes, which cover the spicules as a result. After incorporation, while the opal spicules remain unaltered within sponge tissue, the engulfed quartz particles are quickly etched, reduced in size, and released from the sponge. The etching of quartz particles by C. reniformis is produced by ascorbic acid, and is the first evidence of such activity from the animal kingdom. Ascorbic acid has been found to change the quartz surface features, which leads to an increased radical production and a consequent dissolution of quartz. This process does not occur on opal spicules.
几种海绵物种会摄取各种各样的外来物质。海绵是否会主动选择这些物质存在争议。在此，我们比较了可获取的悬浮物质以及包含在肾形软骨海绵组织中的沉积物。野外观察和实验室实验表明，该物种仅选择并摄取硅质材料，特别是石英颗粒和蛋白石海绵骨针，而避开碳酸盐颗粒。肾形软骨海绵的皮层细胞反应取决于二氧化硅的形态：结晶石英颗粒在海绵表面沉降后，扁平细胞会均匀收缩，形成褶皱表面，这种表面在摄取外来物质的整个过程中都存在。相比之下，蛋白石骨针会引发扁平细胞的运动反应，结果是扁平细胞会覆盖骨针。摄取后，蛋白石骨针在海绵组织内保持不变，而被吞噬的石英颗粒会迅速被蚀刻，尺寸减小，并从海绵中释放出来。肾形软骨海绵对石英颗粒的蚀刻是由抗坏血酸引起的，这是动物界此类活动的首个证据。已发现抗坏血酸会改变石英的表面特征，这会导致自由基产生增加，进而使石英溶解。此过程不会发生在蛋白石骨针上。
