Evolutionary genomics of endosymbiotic bacteria
Beneficial associations between insects and intracellular bacteria are common in nature. These bacterial species are often referred as primary or secondary endosymbionts depending of their role (essential or not) on insect growth and development. Obligate endosymbionts are exclusively vertically transmitted from the mother to the offspring of their respective insect hosts and, during the adaptative process to intracellular life, these bacteria suffer drastic changes in their genomes.
Our goal is to explain the nature of the processes that allow the symbiotic integration of these bacteria in their host insect. We analyze the rhythm, the mode and the consequences of the process of genome reduction that has lead to several of these species to present some of the smallest bacterial genomes known to date. In recent years we have sequenced and analyzed the complete genomes of two Buchnera aphidicola strains (endosymbionts of galling aphid Baizongia pistaceae and cedar aphids, respectively) and Blochmannia floridanus (endosymbionts of carpenter ants). At present we are working on the genomes of two flavobacteria that are primary endosymbionts of the coackroaches Blattela germanica and Blatta orientalis, the primary endosymbiont of rice weevil (SOPE) and a second endosymbiont present in the cedar aphid (Serratia symbiotica BCc).
Our analyses on these reduced genomes have been the start point to a new project focused on the theoretical study of the composition and evolution of hypothetical minimal genomes for autotrophic and heterotrophic bacteria, as well as the properties of the metabolic networks deduced from their genome content.
Genetic studies of aphids: Taxonomy and reproductive polyphenism
Systematics and taxonomy of the aphids are controversial, with several alternative proposals. Our research group intends to disentangle the evolutionary relationships both among the different aphid subfamilies and within particular groups of lower rank taxonomic levels. Our proposal for a basality for the subfamily Lachninae has challenged the traditional view in which Eriosomatinae where the sister group of all other aphid subfamilies. Additionally, we are currently investigating in detail the life-cycle and phylogenetic relationships within Fordini (Eriosomatinae).
Aphids reproduce by cyclic parthenogenesis. Their life cycle is controlled by the length of photoperiod and temperature, with short days typical of autumn and winter promoting sexuality and long days of spring and summer promoting parthenogenesis. However, the molecular basis of how the photoperiodic signal is translated into one or other reproduction mode are completely unknown. We are interested in identifying the genes and routes governing the mode of reproduction in aphids (parthenogenesis vs. sexuality). As there is evidence in other organisms suggesting an involvement of the genes governing the daily rhythms (clock genes) in the control of seasonal rhythms, we are at present characterising the circadian genes in aphids and investigating their role (if any) in seasonality.
Research topics at the FISABIO-Salud Pública
- Genomics of microorganisms
- Metagenomics of microbial communities
- Molecular epidemiology and evolution of microorganisms
- Bioinformatics and biostatistics
