Pectinaria gouldii and Phragmatopoma lapidosa are marine polychaetes that reside in protective structures built from sand grains bound together using proteinaceous cement secreted from specialized glands. P. gouldii constructs a solitary, ice-cream-cone-like structure. The smaller, gregarious P. lapidosa forms a large, reef-like mound. This study investigates the physical features of these two polychaete biocements, linking structure and function in two marine environments.      The surface structures of hydrated biocement samples were analyzed using atomic force microscopy (AFM), and the surface structures and composition of dehydrated biocement samples were analyzed using scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS). Atomic force analyses indicate that (in their native states) the surface roughness, adhesion, and stiffness of P. gouldii biocement are greater than P. lapidosa biocement. The surface of P. gouldii resembled “cottage cheese,” while the surface of P. lapidosa had smoother features. SEM revealed “popped bubble” features that indicated a solid foam-like material for both biocements. EDS confirmed the presence of calcium, magnesium, and phosphorous in both biocements, with varying amounts of these three elements at different locations on the same sample.

Model systems such as E. coli, yeast, and Xenopus oocytes are frequently used to express and purify heterologous proteins for subsequent biochemical analysis. However, some vertebrate proteins, particularly those that are extensively modified, can be toxic and very difficult to purify from these systems. In this study we used GFP as a reporter to investigate the feasibility of expressing heterologous proteins from secretory tissues of transgenic X. laevis. Transgenic tadpoles were generated by restriction enzyme mediated integration. GFP was cloned under the control of the larval keratin promoter to drive expression in the epidermis and under the control of the XAG‐1 promoter to drive expression in the cement and hatching glands. GFP expression in the appropriate tissues was observed using both promoters. However, the XAG‐1 promoter caused GFP to be expressed much more uniformly and robustly. Next, we cloned a signal sequence onto GFP so that it would be secreted. The secreted GFP was assayed using Western blots and a GFP fluorescence assay. Secreted GFP was readily collected from the buffer housing either set of transgenic animals but we obtained the highest yields using animals secreting GFP from the cement and hatching glands. In conclusion, expressing proteins specifically in secretory tissues of transgenic tadpoles is a viable method to obtain heterologous proteins for subsequent biochemical analysis.