Project 2
Bringing light into the dark – function of genetic dark matter in insect symbioses
Supervisors:
Tobias Engl (main supervisor)
Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Jena
Martin Kaltenpoth (co-supervisor)
Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Jena
Background:
Nutritional symbioses are widespread in insects, allowing them to exploit otherwise inaccessible ecological niches. The intimate, long-term association comes with isolation from environmental microbes, genetic drift, strong population bottlenecks but also intra-strain competition for the bacterial partner which results in extremely eroded genomes, retaining only functionally relevant genes in the symbiont genome. The hosts evolved specialized organs (bacteriomes) that provide a cellular and metabolic environment that is optimized to harbor their specific bacterial partners. Both, symbiont genomes, and bacteriome expression profiles contain multiple genes of unknown function. Recent advances of in silico approaches allow to identify putative protein structures and functions, whereas progress in molecular techniques permits testing these functions experimentally.
Project description:
This project focusses on different species of grain beetles that convergently evolved symbioses with similar ecological functions, but different flavors of the functional contribution of their symbionts. Based on comparative symbiont genomics and differential gene expression analyses of host tissues, relevant genes with unknown molecular functions for the host-symbiont interaction can be readily identified. Predictions of protein structure and interaction partners can generate hypotheses of molecular functions and extended functional relevance for the interaction and fitness of both partners.
The aim of this project is to experimentally test these predictions. This includes the localization of effector proteins on an (ultra-)structural level, test for interaction partners in heterologous expression systems, but also manipulation of their gene expression and quantifying impact on symbiosis-relevant traits.
The project will be integrated in the larger group of scientists working on the metabolic interplay and molecular control, as well as eco-evolutionary context of cuticle-supplementing symbioses in beetles. The focus of the project is expected to be co-developed by the successful applicant with an open focus on the best candidate and insect system. The range of applied methods will include refined in silico analyses of existing datasets, silencing of gene expression via RNAi or PNAs, ex vivo cultivation of symbiotic organs, heterologous expression of proteins in insect cell culture or yeast, microscopic techniques incl. live and high-resolution imaging, possibly metabolic analyses and monitoring of phenotypic and fitness related insect traits.
Candidate profile:
• a deep interest in the cellular biology and/or evolutionary ecology of insect-microbe interactions
• a strong background in insect or molecular biology, insect or microbe physiology, microscopy or cell culture
• a steady hand and patience for handling minute structures
• critical scientific thinking skills
• curiosity, creativity, and ambition
• excellent time management and organizational skills
• the ability and willingness to interact with other scientists in the group
• very good communication skills
• proficiency in written and spoken English
Reading:
Anbutsu, H. et al. Small genome symbiont underlies cuticle hardness in beetles. Proc. Natl. Acad. Sci. 114, E8382–E8391 (2017).
Bhattacharrya, S. et. al. Regulation of beneficial intracellular symbionts in insects Current Opinion in Insect Science, 77, 101566
Fiori, C, et. al. Probing metabolic integration in obligate, intracellular symbioses, Current Opinion in Insect Science, 77, 101541
Bublitz, D. C., et al. Peptidoglycan Production by an Insect-Bacterial Mosaic. Cell 179, 703-712 (2019).
Engl, T. et al. Ancient symbiosis confers desiccation resistance to stored grain pest beetles. Mol. Ecol. 27, 2095–2108 (2018).
Kiefer, J. et al. Inhibition of a nutritional endosymbiont by glyphosate abolishes mutualistic benefit on cuticle synthesis in Oryzaephilus surinamensis. Commun. Biol. 4, 554 (2021)
Kiefer, J. et al. Cuticle supplementation and nitrogen recycling by a dual bacterial symbiosis in a family of xylophagous beetles. The ISME J., 17, 1029-1039 (2023)