Beneficial relationships between vertebrates and bacteria have been the subject of intense study, and it is now well established that bacterial communities (microbiomes) of the skin, mouth and digestive system play critical roles in host metabolism and overall health. However, in perhaps the most unique and yet understudied vertebrate-bacteria relationship, evidence suggests that bacteria reside within the blood and organs of healthy sharks, skates and stingrays (elasmobranch fishes). To our knowledge the widespread presence of bacteria within the tissues and organs of a healthy vertebrate is unprecedented, and therefore characterizing the elasmobranch microbiome will provide valuable insight into the evolution of vertebrate immunity and microbial symbioses. This project will provide multidisciplinary graduate student training in elasmobranch biology, bioinformatics and cutting-edge molecular techniques at both the University of Southern Mississippi and the J. Craig Venter Institute.
While previous studies were limited to the identification of bacterial species that could be cultured, this project will use 16S rRNA gene sequencing to identify bacteria present in the blood, kidney and liver of two common species of elasmobranch, the Atlantic stingray and the Atlantic sharpnose shark. The investigators will also validate for the first time the existence and specific locations of these bacteria within tissues using molecular methods as well as transmission electron microscopy. The amplified 16S rRNA genes will allow rRNA gene library construction and bridge amplification. Sequencing will be completed using the MiSEQ platform by Illumina. Analysis and estimation of phylogenetic diversity of 16S rDNA sequence data will be accomplished with clustered high quality trimmed sequences. It is expected that results will verify the presence, location and identity of bacteria within elasmobranch tissues, establishing a new and paradigm-shifting model for the study of vertebrate-bacteria relationships including host metabolism, self-recognition, and immune system function.
