Meeting Abstract
Like most molluscs, chitons (Polyplacophora) have a toothed tongue-like organ called a radula, which they use to feed by rasping food from hard substrates. The teeth of the radula form within an organic matrix of chitin and protein and develop a core of apatite. Unlike most other molluscs, chiton teeth are further hardened with a coating of iron in the form of magnetite. These remarkably strong teeth have an incredible abrasion resistance comparable to that of tank armor and thus are of great interest to researchers in fields ranging from evolutionary biology to biomechanics, but the genomic basis of iron biomineralization in chitons is unknown. To elucidate this process, we are sequencing a draft genome for Acanthopleura granulata, which will join fewer than ten currently sequenced molluscan genomes and represent the first aculiferan. Leveraging a high-quality chiton genome, we will identify candidate gene families involved in iron biomineralization and reconstruct their evolutionary history. Further, we will investigate the genomic basis of chiton radula biomineralization by examining differences in gene expression among four regions of the Acanthopleura radula: the anterior-most segment with fully mineralized but also abraded teeth, a second segment with teeth mineralized with iron, a transitional segment in which iron is first deposited, and a posterior segment comprised of clear teeth with no iron present. A chiton genome will inform all studies of molluscan evolutionary biology, while comparative transcriptomic work on the radula will link phenotypes of interest in material science to corresponding genotypes. Taken together, this work will offer insight into an understudied group of molluscs and their unique physiology.
