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Unravelling the mechanisms that allow endosymbionts to make themselves at home within hosts, from transfer to transit.

Periodic Reporting for period 1 - Host Sweet Home (Unravelling the mechanisms that allow endosymbionts to make themselves at home within hosts, from transfer to transit.)

Reporting period: 2018-10-01 to 2020-09-30

Endosymbiotic bacteria are usually not infectious, they have been thought to exclusively transfer vertically from the host mother to her offspring. However, recent evidences, including from my own research, indicate that the horizontal transfers (HT) of endosymbiotic bacterial strains between host species is taking place, but also that not all strains seem to transfer at the same rate.

Such results led me to hypothesise that endosymbiotic strains not transferring horizontally may have lost the ability to do so and to establish into naïve hosts, contrasting to strains found in divergent host species. Instead of transferring, these strains would transit from a generalist state, able to jump and establish into naïve hosts, towards a more specialist state, and found in one to few host species.

The novelty of this project lies into solving the dilemma associated to the endosymbiotic lifestyle: to maintain the mechanisms allowing transfer between hosts or to transit towards a specialised relationship with one host. ‘Host Sweet Home’ aims to unravel the evolutionary history, and the constraints and outcomes of endosymbiosis. I will produce a large amount of genetic data, which analysis will result in highly significant research in the field of symbiosis, and beyond the field of Evolutionary Ecology. To reach this goal, I use insect hosts-Wolbachia symbionts systems, and take an interdisciplinary approach combining phylogenetic and genomic tools with phenotypic assays.
Two articles were published during the first year of the project, and early termination of the funding:
About the diversity of Wolbachia strains in endemic Malagasi dung beetles, and their implication in species divergence in this species rich clade.
1) Miraldo A, and Duplouy A (2019) High Wolbachia strain diversity in a clade of dung beetles endemic to Madagascar. Frontiers in Ecology and Evolution 7:157.

About the CI phenotype induced by Wolbachia in many insect species, the genetic basis of the phenotype and the potential processes involved in the induction of the phenotype:
2) Shropshire JD, Leigh B, Bordenstein SR, Duplouy A, Riegler M, Brownlie JC, and Bordenstein SR (2019) Models and nomenclature for cytoplasmic incompatibility: caution over premature conclusions - A response to Beckmann et al. 2019. Trends in Genetics.



One article was submitted and can be found open access as a preprint in BioRxiv:
About the effect of a wolbachia strain on teh behavior of its parasitoid wasp host:
3) Abroon P, Ashori A, Duplouy A, and Kishani Farahani H (PrePrint) Wolbachia manipulates host pre-imaginal learning in a parasitoid wasp. BioRxiv doi:10.1101/825455.


Four additional articles are in preparation for submission:
4) About horizontal transfer of Wolbachia strains between 20 species of African butterflies
5) About the Lateral gene transfer of Wolbachia DNA into its host genome
6) About the effect of the Microbiota on the life-history of an insect model organism
7) About the Biogeography of a Wolbachia strain in a European species of damselfly (in collaboration with Prof. Erik Svensson for the Evolutionary Biology unit at Lund University)


Additionally:
I supervised : one Bachelor thesis, two Master thesis and three internships at the Lund University. All students will be co-authors on some of the yet unpublished manuscripts described above
I organized several outreach events which were really well received by both the public, school children and scientists involved (See attached image).
I applied to six (2018) and three (2019) higher Academic positions. I was listed in the top five for at least one of them. The results for the last two positions are yet to be known.
I applied for several grant applications: was granted three (a five year fellowship from the Academy of Finland, a three year fellowship from teh swedish funding scheme FORMAS, and a travel support grant for teaching in Cameroon).
I participated in four meetings (Phylogenetic symposium in Lund Sweden, Gordon conference in Boston USA, genomic workshop in Turkku Finland, Biodiversity meeting in Lund Sweden)
I was invited to four European Universities to present my research: Lund University Sweden, Aarhus University Denmark, Zurich and Basel Universities in Switzerland.

Skills acquired:
I improved my understanding of phylogenetics and phylogenomics in contact with Prof. N. Wahlberg's group, and similarly acquired skills to build my own phylogenetic studies.
I learned new molecular techniques for whole genome library preparations
I acquired skills to analyse metabolomic datasets
My group is well integrated in the Biodiversity unit at the Lund University. I and my master students have presented our research on endosymbionts in insects to our peers during a variety of events (Seminar, invited seminars, conferences, and course seminar). We have also reached to teh general public by organizing or taking part into outreach events.

My group has produced a large genomic dataset, including both hosts and symbionts DNA sequences for a total of 40 insect species and 40 Wolbachia strains. I am collaborating with researcher s from the University of HElsinki to produce additional genomes, and analyzing both teh symbiont DNA material and the host DNA material. We are also developing a protocol for efficiently screen such dataset for endosymbiont DNA ready for whole genome analysis and evolutionary studies of host-symbiont interactions.

Once the protocol and the analyses of the genomes will be published, the genomic material will be made available to the whole scientific community using database such as LepBase or NCBI repository. This material is especially interesting as it will represent one of the largest dataset on endosymbionts from African species.
Melitaea cinxia