Project description:Chitons are marine molluscs that posses a radula, a tongue like appendage containing many rows of microscopic teeth used for feeding. These teeth are hardened through the incorporation of biominerals. Since the original discovery of iron oxide and magnetite in these teeth, a wealth of chemical and structural knowledge has accumulated. The biomineralization process is known to be matrix mediated with precise control of the deposition of a number of different iron and calcium minerals at readily identifiable stages of tooth development. While much is known about the mechanisms of tooth mineralisation, there have been no studies undertaken to identify the genes that regulate this process. This investigation uses microarray technology to analyse the spatial expression of 493 expressed sequence tags (EST) derived from the radula sac of chiton, Acanthopleura hirtosa. A number of ESTs have been deemed significantly differentially expressed in relation to three designated areas of the radula sac. These spatial sections are defined by the variation in biomineral deposits of the radula, being immature radula which lacks any biomineral incorporation, iron deposition and calcium deposition. Additionally, foot muscle was used as a control to specify whether EST expression was specific to the radula and therefore likely involved biomineralization.
Project description:Chitons are marine molluscs that posses a radula, a tongue like appendage containing many rows of microscopic teeth used for feeding. These teeth are hardened through the incorporation of biominerals. Since the original discovery of iron oxide and magnetite in these teeth, a wealth of chemical and structural knowledge has accumulated. The biomineralization process is known to be matrix mediated with precise control of the deposition of a number of different iron and calcium minerals at readily identifiable stages of tooth development. While much is known about the mechanisms of tooth mineralisation, there have been no studies undertaken to identify the genes that regulate this process. This investigation uses microarray technology to analyse the spatial expression of 493 expressed sequence tags (EST) derived from the radula sac of chiton, Acanthopleura hirtosa. A number of ESTs have been deemed significantly differentially expressed in relation to three designated areas of the radula sac. These spatial sections are defined by the variation in biomineral deposits of the radula, being immature radula which lacks any biomineral incorporation, iron deposition and calcium deposition. Additionally, foot muscle was used as a control to specify whether EST expression was specific to the radula and therefore likely involved biomineralization. A total of twelve A. hirtosa specimens were collected and sacrificed for microarray hybridizations. The radulae were removed from each animal immediately following sacrifice and dissected into three sections based on the biomineralisation development of the radula teeth. These sections are termed immature teeth, iron deposited teeth, and calcium deposited teeth. An additional sample of A. hirtosa foot muscle was taken from each specimen. RNA was extracted individually from these sections. Extracted RNA samples across subjects were pooled equally within sections in order to minimize the impact of biological variation and maximize the number of individual samples included in the study. To this effect, four single channel hybridizations were conducted for each radula and muscle section each representing a pooled biological replicate containing equal proportions of RNA from three A. hirtosa individuals. A total of sixteen microarray hybridizations were conducted in this manner.
Project description:Radula is a unique foraging organ to Mollusca, which is important for their evolution and taxonomic classification. Many radulae are mineralized with metals. Although the remarkable mechanical properties of mineralized radula are well-studied, the formation of mineralization from nonmineralized radula is poorly understood. Taking advantage of the recently sequenced octopus and chiton genome, we were able to identify more species-specific radula proteins by proteomics. Comparing these proteomes enable us to gain insight into the molecular components of nonmineralized and mineralized radula, highlighting that iron mineralization in chiton radula is possibly due to the evolution of ferritins and peroxiredoxins. Through in vitro binding assay, ferritin is shown to be important to iron accumulation into the nonmineralized radula. Moreover, radula proteomes are well adapted to their functionality. Octopus radula has many scaffold modification proteins to suit flexibility while chiton radula has abundant sugar metabolism proteins (e.g. glycosyl hydrolases) to adapt to algae feeding. This study provides a foundation for the understanding of Mollusca radula formation and evolution and may inspire the synthesis of iron nanomaterials.
Project description:Radula is a unique foraging organ to Mollusca, which is important for their evolution and taxonomic classification. Many radulae are mineralized with metals. Although the remarkable mechanical properties of mineralized radula are well-studied, the formation of mineralization from nonmineralized radula is poorly understood. Taking advantage of the recently sequenced octopus and chiton genome, we were able to identify more species-specific radula proteins by proteomics. Comparing these proteomes enable us to gain insight into the molecular components of nonmineralized and mineralized radula, highlighting that iron mineralization in chiton radula is possibly due to the evolution of ferritins and peroxiredoxins. Through in vitro binding assay, ferritin is shown to be important to iron accumulation into the nonmineralized radula. Moreover, radula proteomes are well adapted to their functionality. Octopus radula has many scaffold modification proteins to suit flexibility while chiton radula has abundant sugar metabolism proteins (e.g. glycosyl hydrolases) to adapt to algae feeding. This study provides a foundation for the understanding of Mollusca radula formation and evolution and may inspire the synthesis of iron nanomaterials.
Project description:Radula is a unique foraging organ to Mollusca, which is important for their evolution and taxonomic classification. Many radulae are mineralized with metals. Although the remarkable mechanical properties of mineralized radula are well-studied, the formation of mineralization from nonmineralized radula is poorly understood. Taking advantage of the recently sequenced octopus and chiton genome, we were able to identify more species-specific radula proteins by proteomics. Comparing these proteomes enable us to gain insight into the molecular components of nonmineralized and mineralized radula, highlighting that iron mineralization in chiton radula is possibly due to the evolution of ferritins and peroxiredoxins. Through in vitro binding assay, ferritin is shown to be important to iron accumulation into the nonmineralized radula. Moreover, radula proteomes are well adapted to their functionality. Octopus radula has many scaffold modification proteins to suit flexibility while chiton radula has abundant sugar metabolism proteins (e.g. glycosyl hydrolases) to adapt to algae feeding. This study provides a foundation for the understanding of Mollusca radula formation and evolution and may inspire the synthesis of iron nanomaterials.