manzanomaa88@univie.ac.at

If you are interested in cloacal swabs, bacterial culturing, and/or antimicrobial resistance, we’ve got you covered! In this collaborative venture published in Ecology and Evolution, isolated bacteria from Yellow-legged gull chicks were sequenced and screened for antimicrobial resistance genes. We found antimicrobial resistance genes in many Escherichia, Enterobacter, Citrobacter, Hafnia, Klebsiella, and Proteus. Importantly, this study revealed an increase in the diversity of resistant enterobacteria over time (hatching to fledging) in chicks. This increase in diversity was accompanied by an increase in the proportion of individuals carrying bacteria with antimicrobial resistance genes. There are three possible explanations for this observation: 1) food supply change, 2) parents, through time, might forage in different areas, and/or 3) an increasing number of exchanges with other chicks.

Definitely a rough year: further lockdowns, difficulties doing field work, and a lab move. Nonetheless, some good things actually managed to happen during this time.

Back in September, Kevin (a former co-directed master student from the Royal Ontario Museum) joined me at DoME. Kevin will be working with me to explore the ins and outs of bacterial symbioses across strict blood-feeding leeches. In addition, Luka Močivnik from the University of Ljubljana joined me at DoME for one month to work on a pipeline for the phylogenomics of Niphargus, the largest genus of freshwater amphipods (Stay tuned!). Lastly, and despite complications and some deaths, all the leech populations have been successfully moved to the new building.

On the publication side of things, a total of two works were completed in this year. The first has been published in Evolution, and was the result of a recurring collaboration with Jan Oettler and Eva Schultner. In this work we explored the Wolbachia-induced reproductive manipulation between two populations of the ant species Cardiocondyla obscurior infected by two distinct Wolbachia strains. Crosses of infected queens of a Brazilian population with infected male individuals from a Japanese population, resulted in male-biased offspring and reduced lifespan and fecundity of Brazilian queens. This work shows the role of Wolbachia-induced cytoplasmatic incompatibility in creating reproductive isolation between populations of a widely-distributed ant species.

The second work has been published in The ISME Journal, and resulted from a collaboration with current and former members of my new workplace. We performed whole-genome sequencing to analyse the co-obligate symbiotic system of the adelgid Adelges laricis/tardus. We found that both endosymbionts, Profftia and Vallotia (now Mycetohabitans vallotii), show characteristics of evolutionary “young” endosymbionts. On the other hand, they show strong metabolic complementarity in production of essential amino acids and B vitamins. Despite the genome reduction observed in M. vallotii, synteny is well conserved when compared to other Mycetohabitans, with the chromosome + plasmid organisation of its genome maintained. Most notably, we show that M. vallotii likely derived from a fungus-associated endosymbiont, a hitherto unusual evolutionary trajectory for a nutritional insect-associated endosymbiont.

This work was the result of a many many months of exhausting genome assembly, annotation, comparative genomics, and phylogenetics. In this work, we analysed the genome of a newly described co-obligate endosymbiont, Ca. Erwinia haradaeae, of a particular group of aphids within the Cinara genus (Manzano-Marín et. al. 2020). We found that Ca. Erwinia haradaeae, similarly to Buchnera, underwent an early genomic reduction and settled as a co-obligate endosymbiont early before the diversification of the group, likely replacing a pre-existing co-obligate Serratia symbiotica. As expected, they complement Buchnera in key nutritional pathways (riboflavin and biotin) to supply the aphid host with these vitamins. Most significantly, we found these most relevant genes have been horizontally acquired form a Sodalis-like bacterium, highlighting the important role horizontal transfer of genes can play in the establishment and maintenance of beneficial host-microbe associations.

This second work, was the product of a really cool collaboration (I played a very small part) with the Oliver lab and co. (Patel et. al. 2019). Briefly, a facultative Ca. Fukatsuia symbiotica from the pea aphid was cultured in lepidopteran cells and isolated for whole genome sequencing (cool). Full genome analyses and comparative genomics against a co-obligate strain of the same species from a Cinara aphid was performed, and they were not that different. Finally, while Ca. Fukatsuia symbiotica and Ca. Hamiltonella defensa have a strong tendency to co-occur, metabolic complementarity (inferred from available genomes) does not seem to be the basis for this observed characteristic.