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Project 1

Comparative genomics of insect endosymbionts

PhD position. Supervisors: Siv Andersson (UniUppsala) and Amparo Latorre (with support from Lisa Klasson (UniUppsala). Host: UniUppsala. Secondment internship: to UniValencia.

Rationale

Wolbachia infects 20-75% of insects with a host range that also includes isopods, spiders, mites and filarial nematodes. In insect populations, Wolbachia is maternally inherited and induces reproductive disorders to enhance its own spread. Whereas mutualistic endosymbionts of nematodes lack mobile elements, bacteriophages are present in most Wolbachia strains that are reproductive parasites. Comparative genomics have revealed extraordinarily high recombination frequencies in these populations and even provided examples of bacterial gene transfers to the host nuclear genomes, making them excellent model systems for studies of the diversification and innovation in endosymbionts adapted to insects.

Objectives

To better understand the mechanisms underlying divergence and recombination in insect endosymbiont genomes, the objectives of this PhD project are (i) to sequence the genomes of Wolbachia strains isolated from single-, double-and triple-infected Drosophila lineages; (ii) to compare these genomes with each other and with genomes previously sequenced in our group; (iii) to study the abundance, tissue distribution patterns and gene expression of Wolbachia strains in single, double- and triple-infected Drosophila lineages and correlate the observed characteristics with genomic features; (iv) to sequence Drosophila genomes with potential inserts of Wolbachia genes from strains that have first been cured from their Wolbachia endosymbionts; and (v) to study the molecular evolutionary forces affecting Wolbachia genes inserted into the nuclear genome of their hosts.

Key methods

Cultivation of Drosophila, crosses and analyses of progeny, dissections, purification of bacteria, bacterial DNA, bacterial RNA, whole genome sequence amplification, 454 and Solexa sequencing, whole-genome assembly, gene prediction, annotation, comparative genomics, recombination, phylogenetic inferences, quantitative PCR.