Bacteria that cannot be grown in pure cultures make up a large part of the biomass and genetic diversity on earth and play an important role in many system, for example in the many symbiotic associations with eukaryotes.
My research focuses on symbiotic bacteria that cannot live outside of a eukaryotic host cell. My main interests are in finding out how these tight associations affect genome evolution, determining genetic factors involved in host interactions and exploring the diversity of symbiotic bacteria in nature. I mostly use genome sequencing and comparative genomics to try to answer these questions.
Wolbachia is a bacterial genus consisting of only one recognized species, Wolbachia pipientis, with several divergent supergroups. All members are intracellular endosymbionts of invertebrates, and it has been estimated that as many as 15-70% of all insect species on earth are infected by Wolbachia. The infection is transferred maternally from mother to offspring and Wolbachia has evolved at least four different ways to manipulate the host reproduction in order to increase the number of infected females in a population. The most commonly expressed phenotype is cytoplasmic incompatibility (CI) that results in embryonic death in crosses between uninfected females and infected males. The infected females hereby achieve a reproductive advantage over the uninfected females in a population and CI can thus result in spread of the Wolbachia infection throughout a population that was previously uninfected. Additionally, bidirectional CI can occur if the male and female are infected with different Wolbachia strains and has been implicated as a cause of host speciation and is also being exploited as a method for biocontrol of insect disease vectors. As of yet, the underlying molecular mechanism of CI and the genetic factors of Wolbachia that are involved are unknown.
I am currently involved in several genome sequencing projects of Wolbachia strains infecting different Drosophila species with the aim of determining the evolutionary mechanisms involved inshaping their genomes and determining the genetic factors in phenotypic expression. I am also working on the effect of Wolbachia on the host gene expression by using RNAseq.
Diversity of Insect Endosymbionts
Arthropoda is the most species rich of all eukaryotic phylum’s and part of the explanation for their success comes from the ability to exploit new niches, by adapting to unusual and nutrient low dietary regimes, such as vertebrate blood and plant sap. In order to do so, many insect species have developed very tight symbiotic relationships with microorganisms such as bacteria and fungi that provide them with the nutrients that are lacking in their diet. Apart from these nutritional interactions, many insects carry additional symbiotic bacteria of which we currently know quite little, but that in some insects have been shown to provide adaptation for specific conditions.
I have a workflow where we go from collecting single insects to genome sequencing of their bacterial symbionts, using simple lab methods and whole genome amplification. This method allows us to go out and sample the endosymbiotic diversity from many different insect species and from rare or dissected material. The overall goal is to study the diversity and genome evolution of symbionts, and if possible, get an understanding for what they are doing.
For this purpose, I am looking for collaborators who have either interesting symbionts they want to sequence, or who would like to collect insects for screening and sequencing.