Genetic mechanisms of calcareous sponge biomineralization

• Applicant: Dr. Oliver Voigt
• Subject Area: Animal Physiology and Biochemistry ; Evolutionary Cell and Developmental Biology (Zoology) ; Palaeontology
• Term: from 2016 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 319411146

Biomineralization is the biological controlled formation of mineral structures. Many animal groups use biomineralization to form functional structures like skeletons, shells, or teeth. Biominerals are often composite materials of organic and inorganic compounds, which together have different material characteristics than their purely mineral counterparts. It is not well understood for many animals, how the genetic control over the biomineralization process is maintained. With the proposed project we want to study the genetic basis of carbonate biomineralization in calcareous sponges (Phylum Porifera, Class Calcarea). The studies will contribute to open questions of biomineralization of the group and the evolution of genetic biomineralization toolkits within animals in general. Calcareous sponge are the only sponges with the ability to built calcitic spicules. Because this spicules support their soft tissue and provide a large percentage of the animal's body weight, spicule formation can be considered as a key innovation that triggered the radiation of the group. Different types of spicules can be distinguished, and each of them is produced by only two to seven cells in just a few days, making calcareous sponges an optimal model for biomineralization studies. Using a combination of a transcriptomic and proteomic approach, we will identify the genetic biomineralization toolkit of calcareous sponges from both recognized subclasses (Calcaronea and Calcinea). RNA in situ hybridization will be used to document the spatial and temporal expression of key biomineralization genes. Functional studies (in vitro and in vivo experiments) will be used to learn more about the function of these biomineralization proteins, for example their influence on the crystallization process and on spicule shape. Using phylogenetic analyses to reconcile gene trees and species trees, we aim to reconstruct the ancestral set of biomineralization genes for calcareous sponges and compare their biomineralization toolkit to that of other metazoans to gain further insight into the evolution of biomineralization in animals.

• DFG Programme: Research Grants
• Co-Investigators: Dr. Helmut Blum; Professor Dr. Axel Imhof