RUI: Marine Vampire microbiome Project (MVP): Blood-feeding marine invertebrates, and their bacterial accomplices

Occidental College, Los Angeles CA

Investigators

Abstract

Symbiotic partnerships involving two or more species are widespread in nature. One type of symbiosis is between an animal and its microbiome. It is clear that microbes are supremely important to the success of most animals, including humans, and that many dietary strategies would not be possible without these symbiotic bacteria. Blood-feeding marine invertebrates contend with numerous obstacles associated with feeding on the blood of fish and sharks. Blood is a difficult meal to breakdown. It is toxic, and it provides a nutritionally-deficient diet. Bacteria in the digestive systems of nearly all animals examined play critical roles in the exchange of nutrients and digestion of food, and thus contribute to success and survival of the host. However, virtually nothing is known about the role of internal bacteria on the successful survival of blood-feeding marine invertebrates. The research combines a variety of molecular, imaging, and experimental approaches to examine whether internal bacteria positively influence the success of this unusual group of marine parasites. Blood-feeding animals are not only important to study because of their potential symbiotic relationships with microbes, but because of their ability to act as vectors for pathogens, and the harm they cause to fish stocks. Integrated with this project are research opportunities for undergraduates, and the expansion of a college-level course that incorporates active exploration, including contemporary molecular and imaging techniques. The discovery and elucidation of the role of symbiotic microorganisms to animal success is an important area of research. Persistent bacterial presence is believed to play an essential role in host adaptation to specific niches that would otherwise be unavailable, including the exclusive consumption of blood as a source of nutrition by invertebrate parasites. This project will examine the prevalence of bacteria in all categories of known blood-feeding marine invertebrates, the colonization and residence by bacteria of specific animal tissues, and the possible nutritional role fulfilled by the bacteria. Preliminary evidence suggests an association between marine ‘vampires’ and Vibrio bacteria, and a possible evolutionary convergence of this particular marine bacterium as an essential abettor for a diet based solely on blood, by either diet breakdown, nutrient supplementation and/or heme detoxification. Marine blood-feeders will be collected from southern California coastal waters, with subsequent live animal manipulations, high throughput DNA and RNA sequencing analysis combined with fluorescence, electron and laser capture microscopy, to elucidate previously under-appreciated alliances between blood-feeding marine invertebrates and beneficial bacteria. This project will facilitate understanding of the role of internal bacteria on adaptation to specific diets, and will contribute to the growing knowledge base of the field of symbiosis – from cellular biology (symbiotic integration with host cell metabolism) to ecology (interactions between genetically distinct organisms and niche expansion for both). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.