CENTRAL QUESTION: How can investigations of simple marine sponges provide inroads into the design of advanced materials for high-performance electronic, optical, and biomedical applications?
OBSERVATIONAL FIELD STUDIES
Background. Nature is our oldest and most accomplished teacher, yet we have only begun to exploit its ingenuity. Microbes, plants, and animals are masters of engineering, selecting the best designs through billions of years of evolutionary pressure. Their blueprints are imaginative by necessity – and sustainability is always built into their construction plans.
Biomimicry – the science of imitating nature – is an interdisciplinary field of study that seeks to use the lessons learned from nature to develop new technologies and applications that benefit society. Some familiar examples from the terrestrial world include studying a gecko’s foot to develop improved adhesives, or spider silk for the manufacture of stronger fibers.
As a basis to explore this rapidly emerging and fascinating area of inquiry, students will investigate the biomolecular design strategy used by a local marine sponge to produce its silica-based skeletal structures. Although sponges are among the most ancient and simplest animals on Earth, their skeletons are designed with precision that exceeds the capabilities of modern-day engineering. Lessons learned from sponges may ultimately lead to the manufacture of thinner, stronger optical fibers for telecommunication, better shatterproof glass, safer skyscrapers, more efficient solar panels, and simpler and less expensive ways to build semiconductor devices.
Field Work. The orange puffball sponge (Tethya aurantia), a local scientific celebrity in the field of biomimicry, is among a number of marine sponges that inhabit the waters surrounding California’s northern Channel Islands. During underwater abundance surveys of marine invertebrates, CMB student divers will assist our scientists in the identification and collection of various sponge species, including specimens of Tethya aurantia that will be examined in the laboratory. Students will carefully monitor and record habitat structure, location, depth, and other parameters at each collection site.
EXPERIMENTAL LABORATORY STUDIES
Background. Silicon is widely regarded as Earth’s most important element. Indeed, silicon-based products are used for a diverse array of advanced applications, including semiconductors, telecommunication devices, photovoltaics, and drug delivery systems.
The skeleton of Tethya aurantia contains large quantities of tiny fiberglass needles (spicules) that are composed of silicon and oxygen. Scientists have recently discovered that silicatein alpha, a protein that forms a rod-like filament within the central core of these glass-like structures, is responsible for directing their production. If this strategy can be effectively harnessed, these scientific discoveries hold significant promise for the development of a low temperature and environmentally benign catalytic route to the fabrication of valuable materials, including fiber optic cables. Currently, the production of these materials is expensive and labor-intensive, and requires extreme heat, high vacuums, and the use of caustic chemicals.
Laboratory work. During the laboratory component of this program, students will use fluorescent molecular probes in combination with epifluorescence microscopy to monitor the real-time synthesis of spicules in living sponges. These morphological studies will be followed by a detailed ultrastructural analysis of spicule morphology using scanning electron microscopy.
In a more advanced series of laboratory studies, students will explore the biomolecular strategy utilized by T. aurantia to create its silica-based spicules. Using the deduced amino acid sequence of silicatein alpha, students will apply modern bioinformatics tools to identify homologous proteins from an open-access protein database. The students will then generate interactive, three-dimensional models of silicatein alpha, identify catalytic amino acids within its active site (based on its homology to proteins of known function), and develop a suite of small molecule analogs with specific chemical functionalities that could potentially mimic its active site chemistry. These analogs, along with native silicatein extracted from sponge spicules (using a glycerol-based buffer), will then be tested for their ability to encapsulate recombinant proteins in silica, an important first step toward drug delivery applications.