Maluenda Elodie

PhD Student





Symbiosis is a driver of evolution and biodiversity. For example, all eukaryotic organisms live in symbiosis with mitochondria and chloroplasts that are derived from prokaryotic organisms. Symbionts often provide nutritional benefits but can also protect their hosts against pathogens and stress.
The vertically-transmitted symbionts of arthropods depend on the reproductive success of their hosts. In contrast, horizontally-transmitted pathogens and parasites increase their fitness at the expense of host reproduction. Symbionts and pathogens are therefore in conflict over limited host resources. There is currently much interest in how this conflict is resolved.
Ticks are blood-feeding arthropods that are important for public health because they transmit a variety of infectious pathogens. Hard ticks (genus Ixodes) vector spirochete bacteria (genus Borrelia) that cause Lyme disease. Recent studies have shown that many Ixodes ticks are full of microbes with high prevalence (~100%) and vertical transmission. The function of these putative symbionts and their effects on tick fitness and pathogen transmission remain largely unknown.
My research project will study the relationship between the tick, I. ricinus, and these putative symbionts. In addition, we will investigate the interactions between vertically transmitted symbionts and horizontally transmitted pathogens, such as B. afzelii, one of the most common causes of Lyme disease in Europe.

Experimental approach:
I will use antibiotics to manipulate the microbial community in immature ticks. Artificially ‘cleaned’ and control ticks will be fed on B. afzelii-infected or control mice to create ticks carrying different symbiont/pathogen communities. We will measure a variety of tick fitness traits such as molting success, body mass, fat content, and female fecundity. The bacterial communities will be identified using next generation sequencing. The ultimate goal is to understand how symbionts and pathogens interact to influence the fitness of their tick vector.

Teaching Responsabilities 
Teaching practical course in embryology (first year Bachelor students in medical science)