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14th Nov 2023

Hybrid seminar, @FCG-IGC and online. SymbNET / IGC Tuesday Seminar

Maria Zimmermann-Kogadeeva

Affiliation: Multi-omics-based modelling of microbial ecosystems Lab, EMBL, Germany

Title: Quantifying metabolic interactions between the gut microbiota and the host

Abstract: Human gut microbiota, the community of microorganisms residing in our gastrointestinal tract, is implicated in different aspects of host health and disease. One of the mechanisms of how gut microbes can interact with the host is through metabolites, or small molecules that can be exchanged between the organisms. To quantify these microbiota–host metabolic interactions, we develop mathematical models that describe the underlying molecular exchange processes based on time-resolved or static metabolomic measurements. Combining in vitro and in vivo experimental data with such models has revealed that gut bacteria can substantially contribute to the host metabolism of medical drugs. With these models at hand, we investigate different scenarios of host–microbiota interactions and predict how perturbations (e.g. nutrients, antibiotics, medical interventions) change microbiota contributions to host metabolism. We are further expanding these approaches to improve our understanding of how dietary and neuroactive compounds affect microbes and their interactions with the host

 

14th July 2023

Hybrid seminar, @FCG-IGC and online. SymbNET / IGC Friday Seminar

Paul Schultze-Lefert 

Affiliation: MPI for plant breeding research, Cologne, Germany

Title: Plant innate immunity and cell death mediated by intracellular NLR immune receptors

Abstract: Animal and plant immune systems use intracellular nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) to detect pathogens, resulting in the activation of immune responses that are often associated with localized host cell death. Whereas vertebrate NLRs detect evolutionarily conserved molecular patterns and have undergone comparatively little copy number expansion, plant NLRs detect virulence factors that have often diversified in plant pathogen populations, and thus plant NLRs have been subject to parallel diversification. Plant NLRs sense the presence of virulence factors with enzymatic virulence activity often indirectly through their modification of host target proteins. By contrast, phytopathogenic virulence factors without enzymatic activity are usually recognized by NLRs directly by their structure. Recent structural and biochemical analyses have shown that both indirect and direct recognition of plant pathogens trigger the oligomerization of plant NLRs into signaling active heterocomplexes. Assembly into three-layered ring-like structures has emerged as a common principle of NLR activation in plants and animals, but with distinct amino-terminal domains initiating different signaling pathways. I will discuss recent advances in understanding initiation of plant immune signaling triggered by activation of two major classes plant NLRs, containing either a N-terminal Toll/Interleukin 1 receptor (TIR) or a coiled-coil (CC) domain. I will discuss recent advances in understanding the initiation of plant immune signaling triggered by activation of two major classes of plant NLRs containing either an N-terminal Toll/Interleukin 1 receptor (TIR) or a coiled-coil domain (CC).

 

7th July 2023

Hybrid seminar, @FCG-IGC and online. SymbNET / IGC Friday Seminar

Nancy Moran

Affiliation: University of Texas at Austin, Austin, USA

Title: Investigating bacterial gut symbionts of bees

Abstract: The social corbiculate bees include honey bees, bumble bees, and stingless bees. Besides sharing the trait of eusociality, corbiculate bees share similar gut bacterial communities, containing several bacterial species that have co-diversified with their hosts and that live only in bees. These bacteria were recognized relatively recently, and have been characterized in the last decade. Results of lab and field experiments, mostly on honey bees, support a role of this gut community in defense against pathogens, stimulation of the immune system, digestion of dietary plant polysaccharides, and regulation of metabolism, development and behavior. Besides affecting host biology, the members of the bacterial community have many antagonistic interactions among themselves, mediated by different secreted effectors. This talk will give a brief overview of the approaches used for studying bee gut communities, and of some major findings to date.

 

15th Jun 2023

Online

Flora Vincent

Affiliation: Symbiosis in Marine Unicelular Eukaryotes (EMBL Heidelberg, Germany) 

Title: Symbiosis in marine unicellular eukaryotes 

Abstract: Unicellular eukaryotes in the ocean, known as protists, represent as much biomass as all marine animals taken together, and play a major role in our ecosystem. In particular, eukaryotic phytoplankton are photosynthetic microbes responsible for over 25% of annual primary production on Earth. Those microalgae do not live in isolation and instead establish intimate symbiotic interactions from mutualism to parasitism that largely affect their metabolism, development, evolution but also ecosystem dynamics. From viral infection to host-associated microbiomes, we combine laboratory studies using model species and field expeditions in natura to understand the diversity, role and impact of phytoplankton interactions across biological scales.

Raquel Sá-Leão

Affiliation: Molecular Microbiology of Human Pathogens (ITQB NOVA, Oeiras, Portugal)

Title: Shaping the Streptococcus pneumoniae population through the use of vaccines

Abstract: Streptococcus pneumoniae (or pneumococcus) is the main cause of bacterial pneumonia worldwide being associated with significant morbidity and mortality. Colonization of the human upper respiratory tract is a fundamental prerequisite for transmission and disease. Pneumococci are often shielded by a polysaccharide capsule which hinders phagocytosis and is considered its main virulence factor. Over 100 capsular types have been described to date and these are the basis of current pneumococcal vaccines. In 2000, the first pneumococcal conjugate vaccine, targeting seven capsular types (7-valent), became available. Since then, vaccines with expanded valency (up to 20-valent) have been introduced worldwide. In this seminar I will use data from pneumococcal colonization studies conducted in Portugal to show how these vaccines, together with antibiotics, are shaping the pneumococcal population. I will also discuss whether the pneumococcal population might be evolving towards commensality.

Moderation: Samuel Acheampong (FCG-IGC) 

 

20th April 2023

Hybrid seminar, @FCG-IGC and online

Kiran Patil

Affiliation: MRC Toxicology Unit (University of Cambridge, UK)

Title: What drugs and pollutants do to our bugs

Abstract: The microbiota, with mass comparable with vital organs and genetic diversity surpassing that of the host, can modify drugs and other xenobiotics, which can in turn impact microbiome structure and function. Impaired xenobiotics-microbiome-host links can affect various physiological processes ranging from immune to neuronal responses. Yet, microbiota interactions remain unknown for many drugs and other xenobiotics that we are exposed to (e.g., environmental pollutants). I will present results from studies showing extensive chemical-microbiome interactions and discuss implications for One Health.

Mariana Pinho

Affiliation: Bacterial Cell Biology Lab (ITQB NOVA, Oeiras, Portugal)

Title: Mechanisms for regulation of cell cycle progression in the pathogen Staphylococcus aureus. 

Abstract: Unregulated cell cycle progression may have lethal consequences and therefore bacteria have various mechanisms in place for the precise spatiotemporal control of cell cycle events. We have uncovered a new link between chromosome replication/segregation and splitting of the division septum. We found that the divisome protein FtsK, with a DNA translocase domain, regulates cellular levels of a peptidoglycan hydrolase, Sle1, involved in cell separation in the bacterial pathogen Staphylococcus aureus. Upon DNA damage or impaired DNA replication/segregation, Sle1 levels are reduced, halting premature septum splitting and avoiding exposure of an immature cell surface. 

 

24th February 2023

Hybrid seminar, @FCG-IGC and online. SymbNET / IGC Friday Seminar

Pascale Cossart

Affiliation: Institut Pasteur, Paris France; Visiting scientist at EMBL Heidelberg, Germany

Title: How we raised Listeria to the rank of a model system

Abstract: During more than three decades, to investigate the molecular and cellular basis of infections by intracellular bacteria, we have studied the infection by the intracellular bacterium Listeria monocytogenes. This food-borne pathogen disseminates from the gut to the brain and the placenta providing an interesting model to address  a variety of questions such as how bacteria cross barriers, and survive in different niches of the body and how cells react when invaded by a bacterium.  We have used a variety of approaches. Our investigations have led to new concepts not only in infection biology but also in cell biology and epigenetics and in fundamental microbiology (e.g. novel RNA-mediated regulations, and a never described mechanism of antibiotic resistance). More recently our team has discovered that Listeria encodes genes for bacteriocins which play a key role in bacterial interactions with the microbiome, paving the way to understand the role of some intestinal commensals in infection. The talk will highlights some of the most striking results which have raised Listeria to the rank of a model system. For a recent review: Radoshevich L. and P. Cossart. Listeria monocytogenes : towards a complete picture of its physiology and its virulence. Nature Microbiology 2018, 16 : 32- 46

 

16th February 2023

Hybrid seminar, @FCG-IGC and online

Maria Mota

Affiliation: Biology & Physiology of Malaria (IMM, Lisbon, Portugal)

Title: Host-Plasmodium interaction: a tale of symbiosis and pathogenesis

Abstract: Despite renewed eradication efforts from the international community, malaria still exerts an enormous disease burden, with nearly half the planet’s population at risk of infection. Within the human host, the disease-causing Plasmodium parasites pass through two distinct lifecycle stages, each in a different cellular environment. During the liver stage, a single Plasmodium sporozoite will invade a hepatocyte, and while sheltered there, supposedly undetected by the host, gives rise to thousands of new parasites, which will go on to initiate the subsequent blood stage of infection. While only 10-20 new parasites will be generated inside an erythrocyte, consecutive cycles of cell lysis and reinfection causing a potent host response, as well as the symptoms of malaria. The host contribution to infection outcome, on both the cellular and organismal levels has recently moved to center stage. We have identified hepatocyte molecules that modulate the success of liver stage infection, and showed that distinct host factors, not just the parasite itself, drive the onset and severity of diverse malaria syndromes. Our ongoing work indicates that the web of host-Plasmodium interactions is densely woven, with liver stage-mediated innate immune system activation, host nutritional status, and an antagonistic relationship between the two parasite stages themselves all working to modulate the balance between parasite replication and human health

 

26th January 2023 

Hybrid seminar @FCG-IGC and online

Ramya Ganesan

Affiliation: Symbiosis Dept. MPI for Chemical Ecology, Jena Germany

Title: Dynamics and mechanisms of colonization in a beetle associated bacterial symbiont

Abstract: Many animals are associated with symbionts that provide nutrition, defend against pathogens or help detoxify harmful compounds. Among these, extracellular symbionts usually colonize each host generation anew and likely endure physiological and immunological challenges and/or competition from other microbes during this process. We know that microbial traits like motility, adhesion, and stress response factors facilitate colonization in pathogens. However, our knowledge on symbiont colonization factors in beneficial symbionts is limited to a few well-studied systems. We work with Lagria beetles and their defensive Burkholderia symbionts to gain more knowledge on this aspect. An adult female Lagria villosa beetle hosts multiple Burkholderia strains in specialized glands that are accessory to the reproductive system and the bacteria are smeared onto the egg surface during oviposition. On eggs and in early larvae, symbionts protect the host from fungal pathogens by producing anti-fungal compounds. We investigated how a culturable Burkholderia strain colonizes symbiotic structures on the dorsal surface cuticle of larvae, and using the Tn-seq method we identified a number of potential colonization factors. A comparison of genomic capabilities between two coexisting Burkholderia strains leads us to speculate that mechanisms of colonization differ among strains associated with the same host. Thus the Lagria-Burkholderia symbiosis gives us the opportunity to compare colonization strategies among closely related bacteria.

Luís Graça

Affiliation: Lymphocyte Regulation Lab. Instituto de Medicina Molecular João Lobo Antunes (IMM), Lisbon, Portugal

Title: Regulation of antibody production by specialized T follicular substes

 

18th Nov 2022 (Fr)

Hybrid seminar @FCG-IGC and online

Hassan Salem

Affiliation: Mutualisms Research Group, Max Planck Institute for Biology, Tübingen, Germany

Title Beetle-microbe symbioses: Endless forms most functional

Abstract We are interested in the evolutionary processes that shape mutualisms, with emphasis on why they form and how they facilitate adaptation in insects. Using leaf beetles (Coleoptera: Chrysomelidae) as a model, my talk will outline the mechanisms by which these insects house and transmit their obligate bacterial and fungal symbionts, and the consequences of coevolution between microbe and host. Leveraging data from genomic and transcriptomic sequencing, microscopy, and bioassays in both laboratory and field, I will address (i) the metabolic factors defining symbioses within the Chrysomelidae, (ii) how variation in these factors shapes the nutritional physiology and defensive biochemistry of the insect host, (iii) the trade-offs governing symbiont localisation and transmission, and, finally, (iv) the dual symbiotic roles that microbes can, and often do, fulfill. Collectively, my aim is to highlight the key role of symbiosis in facilitating herbivory across Earth’s most speciose animal order, the beetles.

 

10th Nov 2022 (Th)

Hybrid seminar @FCG-IGC and online

Pascale Vonaesch

Affiliation: Microbiota-targeted interventions Lab, DMF-UNIL, Switzerland 

Title: The gut ecosystem in childhood undernutrition

Abstract: Environmental enteric dysfunction (EED) is an inflammatory disease postulated to contribute to stunted child growth and to be associated with intestinal dysbiosis and nutrient malabsorption. Yet, the microbial contribution to EED remains little studied. In the work I will present, we assess for changes in the proximal and distal intestinal microbiota in the context of stunting and EED. To this purpose, we recruited children aged 2-5 years in Bangui, Central African Republic and Antananarivo, Madagascar from December 2016—May 2018 (Afribiota project). We analyzed gastric, duodenal and fecal samples from 627 children using a metabarcoding approach targeting the V4 hypervariable region of the 16S and 18S rRNA gene (bacteria, microeukaryotes) and the full ITS2 region (fungi) and tested for associations with clinical factors such as anaemia, intestinal inflammation, chronic undernutrition and age. We also assessed for asymptomatic pathogen carriage as well as changes induced to the immune system. Last, we investigated the role of bacterial isolates from these children in the pathophysiology underlying stunted child growth. I will end the presentation with some recent follow-up work aimed at developing microbiota-targeting interventions to correct for the observed dysbiosis and re-equilibrate the microbiota for better health.

 

22nd Sep 2022 (Th)

Hybrid seminar @FCG-IGC and online

Ute Hentschel Humeida

Affiliation: Marine Symbioses Unit, GEOMAR - Helmholtz Centre for Ocean Research Kiel, Germany

Title: A Symbiont phage protein aids in eukaryote immune evasion

Abstract: Phages are increasingly recognized as important members of host-associated microbiomes. While recent studies have revealed vast genomic diversity in the virosphere, the new frontier is to understand how phages may affect higher order processes, such as in the context of host-microbe interactions. Here, we combine viral metagenomics with functional assays to investigate the interplay between phages, bacterial symbionts and marine sponges. We find that sponges, although massively filtering seawater, harbour species-specific and even individually unique viral signatures that are taxonomically distinct from other environments. We further discover a symbiont phage-encoded ankyrin domain-containing protein which is widely spread in phages of many host-associated contexts including human. The ankyrin protein (ANKp) modulates the eukaryotic immune response against bacteria as confirmed in macrophage infection assays. We predict that the role of ANKp in nature is to facilitate co-existence in the tripartite interplay between phages, symbionts, and sponges and possibly many other host-microbe associations.

Jahn MT, Arkhipova K, Markert SM, Stigloher C, Lachnit T, Pita L, Kupczok A, Ribes M, Stengel ST, Rosenstiel P, Dutilh BE, Hentschel U (2019). A phage protein aids bacterial symbionts in eukaryote immune evasion. Cell Host & Microbe 26(4):542-550.e5. doi: 10.1016/j.chom.2019.08.019.

Luísa Figueiredo

Affiliation: Biology of Parasitism, Instituto de Medicina Molecular João Lobo Antunes (IMM), Portugal

Title: Antigenic variation in African trypanosomes: small RNA modifications, big impact

Abstract: RNA modifications are important regulators of gene expression. In Trypanosoma brucei, transcription is polycistronic and thus most regulation happens post-transcriptionally. N6-methyladenosine (m6A) has been detected in this parasite, but its function remained unknown. Recently we found that m6A is enriched in 342 transcripts using RNA immunoprecipitation, with an enrichment in transcripts encoding variant surface glycoproteins (VSGs). Approximately 50% of the m6A is located in the poly(A) tail of the actively expressed VSG transcripts. m6A residues are removed from the VSG poly(A) tail before deadenylation and mRNA degradation. Computational analysis revealed an association between m6A in the poly(A) tail and a 16-mer motif in the 3' untranslated region of VSG genes. Using genetic tools, we show that the 16-mer motif acts as a cis-acting motif that is required for inclusion of m6A in the poly(A) tail. Removal of this motif from the 3' untranslated region of VSG genes results in poly(A) tails lacking m6A, rapid deadenylation and mRNA degradation. To our knowledge, this is the first identification of an RNA modification in the poly(A) tail of any eukaryote, uncovering a post-transcriptional mechanism of gene regulation.

 

15th July 2022 (Fr)

Hybrid seminar @FCG-IGC and online

Philipp Engel

Affiliation: Department of Fundamental Microbiology | University of Lausanne (UNIL), Lausanne, Switzerland

Title: Specialized gut microbiota-host interactions in social bees

Abstract: Social animals often harbor specialized microbial communities in their gut. Social interactions facilitate the transmission of gut symbionts from one generation to the next resulting in host-restricted microbial evolution, diversification, and adaptation to distinct ecological niches in the gut. However, the complex nature of gut microbial communities is a formidable challenge to study these eco-evolutionary processes. Moreover, whether gut symbionts can modulate the social behavior of the host, and thereby possibly influence their transmission, is currently unknown. Social bees offer fantastic opportunities to study such aspects of microbiota-host interactions. Honey bees, bumble bees, and stingless bees harbor relatively simple, yet specialized gut bacterial communities that are experimentally tractable. In my talk, I will present recent findings from genomics and experimental approaches showing how bee gut symbionts partition the available ecological niches in the honey bee gut. This includes examples of closely related species that have diversified by adapting to different dietary resources as well as bacteria that feed on host-derived nutrients. I will further present results from automated behavioral tracking of honey bee sub-colonies which revealed that the microbiota increases the rate and specialization of social interactions among hosts. These findings demonstrate that the gut microbiota can modulate emergent group-level behaviors of animals. Such microbiota effects on social behavior may reinforce the evolution of specialized microbiota-host interactions.

 

8th July 2022 (Fr)

Hybrid seminar @FCG-IGC and online

Nicole Dubilier 

Affiliation: Department of Symbiosis | Max Plack Institute for Marine Microbiology, Bremen, Germany

Title: Eating your microbiome: Nutritional symbioses between marine invertebrates and chemosynthetic bacteria. 

Abstract: Symbioses between chemosynthetic bacteria and marine invertebrates were first discovered at hydrothermal vents in the deep sea but are now known to occur in a wide range of habitats including coral reef sediments, seagrass beds, cold seeps and sunken whale carcasses. In these nutritional associations, the bacterial symbionts use chemical energy sources such as hydrogen sulfide to fix CO2 into organic compounds and feed their hosts. Chemosynthetic symbioses have evolved multiple times in convergent evolution from numerous bacterial lineages, and occur in at least nine protist and animal groups such as ciliates, flatworms, mussels, clams, snails, annelids, and nematodes.  In my talk, I will describe how our toolkit of methods ranging from in situ experiments to meta’omic’ and imaging analyses of chemosynthetic symbioses have revealed the biological, ecological and evolutionary processes that drive these host-microbe associations.

 

23rd June 2022

Online

Mikhail Savitski 

Affiliation: Stability Proteomics for assessing the state of the Proteome; Proteomics Core Facility | EMBL, Heidelberg, Germany

Title: Deciphering cellular phenotypes using biophysical proteomics.

Abstract: Thermal stability of proteins can be measured in living cells on a proteome-wide scale using thermal proteome profiling, TPP. While the technology was initially developed to identify drug targets, the improvements in sensitivity now make it possible to detect thermal stability changes which result from modulation of protein-protein, protein-metabolite, protein-DNA interactions etc. Thus TPP has the ability to phenotype cellular states and capture functionally relevant changes not accessible to expression proteomics. Recently we combined TPP with reverse genetics to map the functional landscape of the model organism E. coli. This study will be presented in the talk and will provide an outlook on how this is applicable to the much less well characterized gut microbiome species.

Élio Sucena

Affiliation: Evolution and Development Lab | Instituto Gulbenkian de Ciência (FCG-IGC), Oeiras, Portugal

Title: How the larva got its fly: the co-option of immune mechanisms in the evolution of metamorphosis.

Abstract: Recent years have witnessed the rise of the so-called integrative biology, which fundamentally consists on the dilution of discipline borders to move the explanatory level towards organism-based mechanisms. The evolution of insect metamorphosis has required the establishment of new cross-talks between multiple organ systems and processes, thus constituting a privileged stage for such integrative questions. 
In this work, we unveil a mechanistic link between hormones and immunity in the metamorphosis developmental programme of Drosophila melanogaster by establishing that:
1. There is a peak of antimicrobial peptides (AMP) expression at the onset of metamorphosis which involves three main players: drosomycin, drosomycin-like 2 and drosomycin-like 5;
2. This peak is dependent on the ecdysone peak that induces metamorphic moult;
3. This peak of AMP expression is independent of bacteria presence and canonical immune pathways;
4. This peak of AMPs influences the persistence of bacteria throughout metamorphosis.
Furthermore, we show that this immune response acts both locally and systemically deploying specific AMPs in each of these contexts, through ecdysone signalling in a Broad-dependent manner.
This endocrine regulation of immunity effectors at the onset of metamorphosis increases the success of this developmentally critical period and, by extension, that of the holometabolan programme. We speculate that this co-option of immunity by the metamorphosis programme may constitute an anticipatory response that has evolved to face the strong selective pressure imposed by the inherent risk of infection this novel transition entails.

Catarina Nunes [1], Takashi Koyama [1][2], Élio Sucena [1][3]: [1] Instituto Gulbenkian de Ciência, Oeiras, Portugal; [2] Department of Biology University of Copenhagen, Copenhagen, Denmark; [3] Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal

 

6th June 2022 (Mo) 

Hybrid seminar @FCG-IGC and online

Nassos Typas

Affiliation: Systems Microbiology Lab | EMBL, Heidelberg, Germany

Title: Probing the interface of drugs and the human gut microbiome.

Abstract: Drugs both impact the human gut microbiota and their bioavailability is modified by gut microbes. Here, I will be presenting recent highlights from coordinated efforts at EMBL to systematically map this drug-microbiome interface, to understand its impact on the gut microbiota and on drug efficacy, to address whether communities have emergent behaviours against drugs, and to discover ways to mitigate the collateral damage of drugs, and especially of antibiotics, on gut microbes.

 

19th May 2022

Online

Jan Van der Meer

Affiliation: Environmental and Evolutionary Microbiology Lab | University of Lausanne (UNIL), Switzerland

Title: Culturing and managing complex soil microbiomes.

Abstract: Soils harbour among the most species-complex known microbial communities, which are thought to be key for plant health and ecosystem services like element cycling, carbon storage, or water purification. How soil communities form or how their equilibria maintain is largely unknown. In order to better understand intricacies of soil community growth, we focus on developing methodologies to reproducibly culture communities, measure interspecific interactions and provide management strategies to introduce specific metabolic functionalities.   

Tina Keller Costa

Affiliation: Institute for Bioengineering and Biosciences | Instituto Superior Técnico (IST), Portugal

Title: The Microbiome of Octocorals: Community structure, Function, and possible Metabolic Interactions

Abstract: Octocorals (Octocorallia, Cnidaria) are an integral part of benthic marine ecosystems. They increase habitat complexity and biodiversity and play key roles in coastal food chains, helping to regulate primary and secondary production. They are found in association with various microorganisms, including micro-eukaryotes, prokaryotes, and viruses. However, the role of their microbial symbionts is still poorly understood. In this talk, I will present our research on the microbiomes of temperate octocoral species using cultivation-dependent and -independent, metagenomics approaches. I will identify functional features that collectively may contribute to the stabilization of symbiosis, and that suggest niche partitioning and metabolic specialization among symbionts which could contribute to the plasticity and adaptability of the octocoral holobiont in changing marine environments.

 

21st April 2022

Online

Nils Raedecker 

Affiliation: Laboratory for Biological Geochemistry | EPFL-UNIL, Switzerland

Title: Resource competition regulates the cnidarian-algal symbiosis

Abstract: The evolutionary success of the cnidarian-algal symbiosis has given rise to the formation of coral reef ecosystems. Yet, climate change and other anthropogenic impacts are disrupting this symbiosis at increasing frequencies and scales. Understanding the collapse of this symbiosis will not be possible without considering its ecological foundation: the nutrient exchange between coral host and algal symbiont. Combining physiological, Omics, and NanoSIMS imaging approaches, our work focuses on metabolic regulation of symbiotic interactions in the onset, maintenance, and breakdown of the cnidarian-algal symbiosis. Our findings suggest that stable mutualistic nutrient exchange in the symbiosis can passively arise from competition for inorganic nutrients between the host and its symbionts. A breakdown of this resource competition during heat stress, in turn, destabilizes nutrient cycling and thus the symbiosis itself. Taken together, we conclude that the functioning of this symbiosis is a direct consequence of the coupling of heterotrophic and phototrophic metabolisms. While this passive regulation has underpinned the evolutionary success of coral holobionts for millions of years, it also renders these organisms highly vulnerable to the rapid environmental change of the Anthropocene. 

Ricardo Henriques 

Affiliation: Optical Cell Biology Lab | Instituto Gulbenkian de Ciência (FCG-IGC), Oeiras, Portugal

Title: Open technologies for Super-Resolution and Machine Learning in BioImaging

Abstract: Super-resolution microscopy has become essential for the study of nanoscale biological processes. This type of imaging often requires specialised methods to collect and process a large volume of recorded data and extract quantitative information. In recent years, our team and collaborators have built an open-source ecosystem of computational, biochemical and optical approaches for live-cell super-resolution microscopy, designed to combine high performance and ease of use. This talk will present some of these approaches such as SRRF, SQUIRREL, VirusMapper, Super-Beacons, ZeroCostDL4Mic and vLume, showcasing their application in the study of biological processes such as viral infection. 

Moderation: Tânia Paulo (FCG-IGC) 

 

17th March 2022

Online

Jordi Van Gestel

Affiliation: University California, San Francisco (UCSF)

Title: Short-range quorum sensing controls horizontal gene transfer at micron scale in bacterial communities.

Abstract: In bacterial communities, cells often communicate by the release and detection of small diffusible molecules, a process termed quorum-sensing. Signal molecules are thought to broadly diffuse in space; however, they often regulate traits such as conjugative transfer that strictly depend on the local community composition. This raises the question how nearby cells within the community can be detected. Here, we compare the range of communication of different quorum-sensing systems. While some systems support long-range communication, we show that others support a form of highly localized communication. In these systems, signal molecules propagate no more than a few microns away from signaling cells, due to the irreversible uptake of the signal molecules from the environment. This enables cells to accurately detect micron scale changes in the community composition. Several mobile genetic elements, including conjugative elements and phages, employ short-range communication to assess the fraction of susceptible host cells in their vicinity and adaptively trigger horizontal gene transfer in response. Our results underscore the complex spatial biology of bacteria, which can communicate and interact at widely different spatial scales.

Jonathan Howard 

Affiliation: Host-Pathogen Co-evolution Lab | Instituto Gulbenkian de Ciência (FCG-IGC), Oeiras, Portugal

Title: The maintenance of avirulence in Toxoplasma gondii.

Abstract: The transmission of  T. gondii is dependent on avirulence, guaranteeing lifelong parasitism. The selective cost of infection to the host is not balanced by any competing advantage; the optimum strategy for the host is to defeat the parasite. Thus the avirulent state has to defend itself against the Scylla of rapid elimination by host immunity and the Charybdis of virulence resulting in acute death of the host. I will discuss a novel aspect of this phenomenon, in which host and parasite conspire to limit the intensity of the initial immune attack, allowing the parasite to escape and encyst in the brain.

Moderation: Catarina Carmo (FCG-IGC) 

 

17th February 2022

Online

Maria Zimmermann-Kogadeva

Affiliation: Multi-omics-based modelling of microbial ecosystems Lab | EMBL, Heidelberg, Germany

Title: Quantifying gut microbiota contribution to the host metabolism of medical drugs and dietary compounds.

Abstract: The gut microbiota plays an essential role in host health, helping to catabolize indigestible nutrients and engaging in host metabolism. However, quantifying microbial contribution to the host metabolism remains challenging due to the complexity of host-microbiota relationships and the fact that most metabolites are indistinguishable between organisms. To disentangle diet, host and microbiome contributions to the host metabolism of medical drugs and dietary compounds, we combine controlled gnotobiotic mouse experiments and multiomics data integration with mathematical modelling and metabolic network analysis. We colonize germ-free mice with single bacterial species or synthetic communities, and compare drug metabolism or diet response in the colonized mice against germ-free mice. We collect large-scale metabolomic data across mouse tissues, and develop dynamic and steady-state metabolic models to quantify microbiota contribution to metabolite profiles. To identify bacterial players and their pathways responsible for the microbiota-associated metabolism, we collect metagenomic and metatranscriptomic data and integrate them into genome-scale metabolic networks. This combination of experimental and computational approaches unravels mechanistic links between drugs, diet, microbiota and the host, and provides insights into how compositional shifts and metabolic adaptation of single bacteria might affect community metabolism.

Waldan Kwong

Affiliation: Microbial Genomics and Symbiosis Lab | Instituto Gulbenkian de Ciência (FCG-IGC), Oeiras, Portugal

Title: Bees & Corals: Microbial insights from diverse model systems

Abstract: Microorganisms have developed numerous ways of interacting with each other and with eukaryotic hosts, but most of these evolutionary innovations remain unknown and uncharacterized. Here, I present work in two systems – social bees and corals – where the combined use of genomic sequencing and environmental surveys have helped unravel the identity and function of their respective microbial communities. I show that, even from these well-studied animal hosts, novel insights into microbial cell biology, evolution, and symbiosis can be gleaned. As technological capabilities in sequencing and cultivation improve, the study of diverse model systems will become more accessible and rewarding, by opening up a previously untapped world of microbial diversity.

Moderation: Nelson Frazão (FCG-IGC) 

 

20th January 2022

Online

Philip Rosenstiel 

Affiliation: Systems Immunology Group | IKMB, Kiel University (CAU), Kiel, Germany

Title: Dietary factors license host-microbe interactions at the intestinal barrier

Adriano Henriques 

Affiliation: Microbial Development Lab | ITQB NOVA, Oeiras, Portugal

Title: Structure and assembly of the Clostridiodes difficile spore surface layers

Moderation: Vitor Cabral (FCG-IGC) 

 

16th December 2021

Online

Nassos Typas 

Affiliation: Systems Microbiology Lab | EMBL, Heidelberg, Germany

Title: A tripartite toxin-antitoxin system sensing and defending phage.

Abstract: Retrons are genetic retroelements, commonly found in bacterial genomes and recently repurposed as genome editing tools. Their encoded reverse transcriptase (RT) produces a multi-copy single-stranded DNA (msDNA). Despite our understanding of their complex biosynthesis, the function of msDNAs and therefore, the physiological role of retrons has remained elusive. We have recently established that the Retron-Sen2 in Salmonella Typhimurium encodes a novel family of tripartite toxin/antitoxin systems, which is activated during phage infection to protect against phages through abortive infection.

Luís Moita 

Affiliation: Innate Immunity and inflammation | Instituto Gulbenkian de Ciência (FCG-IGC), Oeiras, Portugal

Title: Induction of immune responses by surveillance of homeostasis perturbations.

Abstract: Several classes of antibiotics have long been known to have beneficial effects that cannot be explained strictly on the basis of their capacity to control the infectious agent. We found that tetracycline antibiotics, which target the mitoribosome, protected against sepsis, without affecting the pathogen load. Mechanistically, we demonstrate that mitochondrial inhibition of protein synthesis perturbed the electron transfer chain (ETC) decreasing tissue damage in the lung and increasing fatty acid oxidation and glucocorticoid sensitivity in the liver. Using a liver-specific partial and acute deletion of Crif1, a critical mitoribosomal component for protein synthesis, we found that mice were protected against sepsis, an observation which was phenocopied by the transient inhibition of complex I of the ETC by phenformin. Together, we demonstrate that mitoribosome-targeting antibiotics are beneficial beyond their antibacterial activity and that mitochondrial protein synthesis inhibition leading to ETC perturbation is a mechanism for the induction of disease tolerance.

Moderation: Carina Galhofa (FCG-IGC) 

 

26th November 2021

SymbNET @IGC Friday Seminar, Online

Eduardo Rocha 

Affiliation: Microbial Evolutionary Genomics Lab | Institut Pasteur, Paris, France 

Title: Bacteria and their mobile elements: how networks of shifting interactions drive genome evolution

Abstract: Horizontal gene transfer driven by self-mobilizable genetic elements allows the acquisition of complex adaptive traits and their transmission to subsequent generations. Transfer speeds up evolutionary processes as exemplified by the acquisition of virulence traits in emerging infectious agents and by antibiotic resistance in many human pathogens. Transfer is also costly because the vectors of horizontal transfer compete within genomes, have their own mobile elements and are often deadly. As a result, genomes are repositories of multiple immune systems from hosts and from mobile elements that interact in complex ways to drive gene flow in communities. The combination of evolutionary genomics and sequence analysis is now opening up these processes to show how they bring into the genome a constant flux of novel genes that favor the establishment and the invention of novel functions.

 

25th November 2021

Online

Julijana Ivanisevic 

Affiliation: Metabolomics Unit | University of Lausanne (UNIL), Switzerland 

Title: Metabolomics: Assessing the small molecule component of metabolism  

Abstract: Metabolomics, including lipidomics, is emerging as a quantitative biology approach for the assessment of energy metabolism and information flow through metabolic signaling. Thereby, omic-scale metabolite analysis can provide novel insights into metabolism and its regulation, in different physiological conditions, from diverse model system to human populations. When combined with orthogonal molecular biology approaches, the findings can lead to novel mechanistic insights to enhance the functional understanding of a studied biological system. In this presentation, I will provide an overview on the role of metabolomics in this postgenomic era of biochemistry and its application to investigate metabolite role and (bio)activity, from model systems to human population studies. I will present the challenges inherent to this analytical science, and approaches and modes of analysis that are used to resolve, characterize and measure the infinite chemical diversity contained in the metabolome (along with lipidome) of complex biological matrices.

Sarela Garcia-Santamarina 

Affiliation: Human Microbiota - Xenobiotics Interactions | ITQB NOVA, Oeiras, Portugal 

Title: Microbe – Xenobiotics interactions: from single species to communities 

Abstract: In this Symbnet seminar, I will first talk about how responses to commonly used medications compare between bacteria grown in isolation and bacteria grown in a complex community. We found that new interactions emerge in the community setting in a quarter of the tested conditions, including cross-protection of drug-sensitive strains and cross-sensitization of drug-resistant strains. Cross-protection mechanisms were more frequent, indicating that communities are more resilient to stress than individual bacteria. However, community resilience is compromised when drug concentrations increase. We evidence that drug metabolism and drug bioaccumulation contribute to a large fraction of the community behaviors. Finally, by following up on a specific case of communal protection, we established how cross-protection mechanisms are transferred from monoculture to community. In the second part of my talk, I will introduce my vision of the new laboratory that I am establishing at ITQB, in which I intend to study the effects of transition metals on the human gut microbiota, at various levels: gene, strain, community and interaction with the host.

Moderation: Maria Montya (FCG-IGC) 

 

21st October 2021

Online

Michael Zimmermann

Affiliation: Metabolic host-microbiome interactions Lab | EMBL, Heidelberg, Germany 

Title: Identify microbiota contributions to xenobiotic metabolism and toxicity

Abstract: Individuals vary widely in their drug responses, which can be dangerous and expensive due to significant treatment delays and adverse effects. Growing evidence implicates the gut microbiome in this variability, however the molecular mechanisms remain mostly unknown. To systematically map the drug metabolizing capacity of the gut microbiota and to assess its potential contribution to drug metabolism, we measured the ability of 76 diverse human gut bacteria to metabolize each of 271 oral drugs. We found that two thirds of these drugs are chemically modified by at least one of the tested microbes. Through combination of high-throughput bacterial genetics with mass spectrometry, we systematically identified drug-metabolizing microbial enzymes. Further, we developed experimental and computational approaches to separate host and gut microbiota contributions to drug metabolism in vivo. These allowed us to quantify and predict microbiota contributions to drug metabolism and toxicity. These causal links between microbiota gene content and metabolic activities connect inter-individual microbiome variability to interpersonal differences in the metabolism of drugs and other xenobiotics. 

Miguel Soares 

Affiliation: Inflammation Lab | Instituto Gulbenkian de Ciência (FCG-IGC), Oeiras, Portugal

Title: On How The Loss Of a Glycan Shaped Primate Evolution

Abstract: Most mammals express a functional GGTA1 gene encoding the N-acetyllactosaminidea-1,3-galactosyl-transferase enzyme, which synthesizes Gal-alpha1-3Gal-beta1-4GlcNAc (alpha-gal) and are thus tolerant to this self-ex-pressed glycan. Old World primates including humans, however, carry loss-of-function mutations in GGTA1 and lack alpha-gal. Presumably, fixation of such mutations was propelled by natural selection, favoring the emergence of alpha-gal-specific immunity, conferring resistance to alpha-gal-expressing pathogens. Here, I will discuss the findings from Sumnima Singh PhD Thesis at the Instituto Gulbenkian de Ciência, showing that loss of Ggta1 function in mice shapes the bacterial composition of the gut microbiota and enhances resistance to bacterial sepsis, irrespectively of alpha-Gal-specific immunity. Rather, the absence of alpha-gal from IgG-associated glycans increases IgG effector function via a mechanism associated with enhanced IgG-Fc gamma receptor (FcgR) binding. The ensuing survival advantage against bacterial sepsis comes alongside a cost of accelerated reproductive senescence in Ggta1-deleted mice. Mathematical modeling of this trade-off suggests that high exposure to virulent pathogens exerts sufficient selective pressure to fix GGTA1 loss-of-function mutations, as likely occurred during the evolution of primates toward humans.

Moderation: André Pimentel (FCG-IGC) 

 

30th September 2021

Online

Sara Mitri 

Affiliation: Evolutionary Ecology of Microbial Communities | University of Lausanne (UNIL), Switzerland 

Title: Eco-evolutionary dynamics in a small bacterial community

Abstract: Microbial communities in soil or the mammalian gut typically contains tens to hundreds of microbial species. These ecosystems are constantly changing, as the community first assembles and as species adapt to each other and to their environment. Because studying such dynamics in a natural system is extremely challenging, in my lab we adress this question using small bacterial communities as model systems. I will first talk about a study where we show how the interactions between four bacterial species depend on their environment: the harsher the environment, the more likely it is for species to interact positively. We then ask how these interactions evolve over time, and find that interactions do not become competitive, but some positive interactions are lost depending on the ability of the species to survive alone. These results provide an intuition on how microbial species in more natural environments may adapt to one another over evolutionary time-scales.

Maria João Amorim 

Affiliation: Cell Biology of Viral Infection Lab | Instituto Gulbenkian de Ciência (FCG-IGC), Oeiras, Portugal

Title: New paradigms in influenza A virus research

Abstract: Viruses thrive on specific hosts where they may cause disease and thus are highly relevant for ecosystems, health and agriculture. Due to the small size of their genomes, they are highly dependent and adapted to the host they infect. Many viral life cycles, including influenza A virus (IAV), form specialized compartments which promote immune evasion, and progeny virion production. My laboratory showed that upon IAV infection, specialized compartments called viral inclusions are formed in the cytosol of infected cells. These are enriched in progeny RNA and constitute sites to assemble IAV genomic complex - that is composed of 8 (and no more than 8) different RNA segments. We showed that these inclusions are membraneless and adopt the hallmarks of classical biomolecular condensates. In this seminar, I will show that IAV liquid inclusions display liquid-liquid phase separation (LLPS) traits whose formation is regulated by concentration and maintained by weak interactions between the components in inclusions. In addition, we provide evidence for the need to maintain IAV inclusions fluid and show that phase transitions are possible and reduce viral production.

Moderation: Miguel Landum (FCG-IGC) 

 

26th August 2021

Online

Vladimir Benes 

Affiliation: Genomics Core Facility | EMBL, Heidelberg, Germany 

Title: A new way to analyse DNA methylation: move over bisulfite  

Abstract: For us in GeneCore, an opportunity to use the new EM-seq system launched recently by NEB has been a true game changer. In addition to its attractive features, such as user-friendliness and cleanliness of the process, for example, we have realized that it enables us to determine in precise and DNA sparing way the cytosine methylation status even at low integrity DNA. If bisulfite conversion were the only approach to apply, we would definitely fail to generate relevant results. The cool, biochemical approach the system is utilizing also opens new opportunities to analysis of cytosine methylation across the whole spectrum of DNA fragments: from very short cfDNA to intact long DNA fragments.

Ricardo Leite 

Affiliation: Genomics Unit | Instituto Gulbenkian de Ciência (FCG-IGC), Oeiras, Portugal 

Title: Unveiling new niches for Legionella spp.

Abstract: Legionella is an emerging environmental pathogen of an increasing concern to human health. This genus includes L. pneumophila and other species that cause the acute pneumonia Legionnaires disease, on the rise worldwide. Using a metagenomic approach, we discovered Legionella spp. in an extremely acidic and heavy-metal rich mining lake in Spain. Combined data from different genomic approaches (metagenomics, RNA-Seq and Nanopore long reads) yielded an unanticipated array of genes associated with pH homeostasis, metal tolerance, virulence and motility, providing important clues to the varied niches Legionella occupies in this extreme environment.

Moderation: Nelson Martins (FCG-IGC) 

 

22nd July 2021

Online

Tal Dagan 

Affiliation: Genomic Microbiology | Kiel University (CAU), Kiel, Germany

Title: The Darwinian fitness of extrachromosomal genetic elements  

Abstract: Plasmids are an important source of raw material for microbial genome evolution outside the mainstream of bacterial chromosomes. Nonetheless, many plasmids found in nature are lacking a clear trait that is advantageous to their host; the determinants of plasmid evolutionary success in the absence of plasmid benefit to the host remain understudied. Borrowing terminology from evolutionary biology of cellular living forms, we hypothesize that Darwinian fitness is key for the plasmid evolutionary success. In the seminar I will present recent results from my group on the determinants of plasmid fitness, and how plasmid fitness might change depending on the environmental conditions. Finally, I will discuss how plasmid-centric view can help us to find general principles for the evolution of host-microbe interactions.

Isabel Gordo 

Affiliation: Evolutionary Biology | Instituto Gulbenkian de Ciência (FCG-IGC), Oeiras, Portugal

Title: Evolution in the mammalian gut

Abstract: Bacteria are known to adapt very rapidly to different selective pressure when grown in simple laboratory environments. However, we still understand little about their adaptive dynamics in natural ecosystems. Given their large population sizes when colonising the intestine, commensals have a tremendous potential for rapid evolutionary change in short time scales. By performing experimental evolution in vivo, we find that the successful colonisation of a newcomer Escherichia coli strain to the gut depends on the level of microbiota diversity in this ecosystem, and its mode of evolution on the presence of a closely related resident strain. Tracking the emergence of de novo mutations and their trajectories reveals two distinct modes of E. coli adaptation to the gut: one characterised by the coexistence of emerging ecotypes, another by recurrent selective sweeps and horizontal gene transfer events. Our results show that genes, phages and plasmids can be gained and lost on time scales of hundreds of generations. They further show the readiness with which strains of E. coli can retain and domesticate newly arriving mobile genetic elements, which can carry simultaneous benefits and costs. The observed pattern of metabolic evolution lends support to the hypothesis that the gut is a crowded restaurant, where genomes evolve to rapidly pick an available dish and co-evolve by shuffling genes from other strains. 

Moderation: Jessica Thompson (FCG-IGC) 

 

16th July 2021

SymbNET @IGC Friday Seminar, Online

Thomas Bosch (CAU)

Affiliation: Cell and Developmental Biology Lab | Kiel University (CAU), Kiel, Germany

Title: Spontaneous body wall contraction shape and stabilize the symbiotic microbiota in Hydra

Abstract: Rhythmic spontaneous contractions of body walls, such as those of the gastrointestinal tract, are a ubiquitous phenomenon in the animal kingdom. Studies in mice and humans have implied that intestinal dysmotility is associated with a disturbed microbiota, but the causal relationship has been unclear. Here, by applying experimental and theoretical approaches in the model Hydra, we provide functional evidence that reducing the frequency of spontaneous body wall contractions alters the fluid microenvironment near the tissue surface and thereby modifies the composition of the colonizing microbiota. Our findings suggest that spontaneous contractions of body walls enhance the transport of chemical compounds from and to the tissue surface where the bacteria reside, thus shaping and stabilizing the host-microbe associations.

 

17th June 2021

Online

Rob Finn (EMBL-EBI)

Affiliation: Microbiome Informatics | EMBL-EBI, Cambridge, UK

Title: Broadening our genomic knowledge of the human microbiomes.

Abstract: The human body is host to trillions of microbes, collectively referred to as the human microbiome, which have adapted to a range of body sites, such as the gut, oral cavity and skin. A variety of factors can affect microbial imbalance, which has a close relationship with human health and disease. Metagenomics, the analysis of the sum of genetic material from a sample, is shedding light on the huge diversity of microbe that occupy these different environments provided by the human host. We have recently published the Unified Human Gastrointestinal Genome (UHGG) catalog, an unprecedented collection of nearly 5,000 gut species found in the the gut microbiome, with 70% yet to be cultured. We have also commenced efforts to recover genomes from the human skin microbiome, which not only harbours a very distinct microbial composition compared to the gut, but also carries additional challenges such as low DNA yield. For both microbiomes, we have started investigating the microbiota beyond bacteria, to reveal the complexity of the entire microbiota.

Jingtao Lilue (FCG-IGC)

Affiliation: Bioinformatics Unit | Instituto Gulbenkian de Ciência (FCG-IGC), Oeiras, Portugal

Title: Searching for the reason of virus susceptibility from Cotton rat genome

Abstract: The cotton rat (Sigmodon hispidus), a rodent species native to the Americas, has served as a valuable laboratory model for infections by numerous viral pathogens in humans, including poliovirus and respiratory syncytial virus. We have finished the reference assembly of the cotton rat genome at a chromosomal level. From this data we suggest specific genetic innovations unique to this species, involved in viral defence. Compared with other sequenced species, we found these immune related loci are also highly dynamic in other rodent species.

Moderation: Tanja Dapa (FCG-IGC) 

 

20th May 2021

Online

Hinrich Schulenburg

Affiliation: Evolution Ecology and Genetics | Kiel University (CAU) and Max-Planck Institute for Evolutionary Biology Ploen, Germany

Title: Evolution of C. elegans - microbe interactions

Abstract: Microbial interactors are key determinants of the biology of any organism. The model nematode C. elegans provides an ideal host system to study these interactions, because of the large variety of tools and the enormous biological database available for this worm. I here provide an overview of our current understanding of the worm’s interaction with naturally associated microbes. I will focus on the worm’s native microbiome and the evolutionary interactions between C. elegans and some of the bacteria. Our work revealed an influence of the microbes on metabolism, developmental processes, reproduction, and especially immune defense. We further identified the bacterial traits and underlying genes, which are essential for the bacteria’s adaptation to the host environment. Our findings provide new insights into the evolution of host-microbe associations and highlight the nematode C. elegans as a tractable model system to dissect the genetics and dynamics of these interactions.

Karina Xavier

Affiliation: Bacterial Signalling | Instituto Gulbenkian de Ciência (FCG-IGC), Oeiras, Portugal

Title: Manipulation of Bacterial Quorum Sensing in the Mammalian Gut Microbiota.

Abstract: The mammalian gastrointestinal tract harbours a diverse and complex resident bacterial community composed of hundreds of species, which interact with each other and the host, and which can influence many processes required for optimal host health. We asked if bacterial cell-cell communication, mediated by quorum sensing, could shape the species interactions occurring in the highly dense and competitive gut environment. Quorum sensing is a cell-cell signalling process used by many different bacteria to regulate bacterial group behaviours. We have established a mouse model to manipulate quorum sensing mediated by the signal AI-2, directly in the mouse gut. Our work provided the first evidence that the quorum sensing signal AI-2, which foster inters-species communication, can influence the species composition of the major bacteria phyla of the gut microbiota. Moreover, our results indicate that forcing the microbiota to committee to quorum sensing during antibiotic-induced microbiota imbalances (dysbiosis) can promote recovery of gut homeostasis. To identify the molecular basis of AI-2 regulated microbiota responses, we used an ecological based mathematical model to model microbiota dynamics during dysbiosis and infer AI-2-mediated species interactions, which were then tested with gene expression studies. Our results indicate that AI-2 inhibits the expansion of Bacteroides vulgatus, the major pathobiont in antibiotic induced dysbiosis. Our working model predicts that AI-2 inhibits pathobiont expansion by inhibiting a nutrient sharing network between B. vulgatus and the closely related microbiota member Bacteroides ovatus.

Moderation: Migla Miskynite (FCG-IGC) 

 

22nd April 2021

Online

Philipp Engel

Affiliation: Department of Fundamental Microbiology | University of Lausanne (UNIL), Lausanne, Switzerland

Title: Understanding microbiomes - Insights from bees and their gut symbionts

Abstract: Specialized bacterial communities colonize the animal gut and impact health and disease of the host in manifold ways. However, the complex composition of these communities presents a veritable challenge for disentangling gut microbiota functions, to assess their diversity, or to understand the ecology and evolution of individual community members. In my lab, we study the gut microbiota of social bees. Honey bees, bumble bees, and stingless bees harbor simple, yet highly specialized, bacterial communities in their guts. These bacteria are experimentally amenable and gnotobiotic bee models have been established, which makes bees great models for addressing current questions of gut microbiota research. We combine experimental and genomic approaches to assess how diversity has evolved and is maintained in these communities, and which functions are carried out by which community member. In my talk, I will give an overview on bee microbiome research and summarize recent projects we have carried out in our lab.

Luís Teixeira 

Affiliation:  Host-Microorganism Interactions | Instituto Gulbenkian de Ciência (FCG-IGC), Oeiras, Portugal

Title: Functional genomics of the endosymbiont Wolbachia

Abstract: Wolbachia is an intracellular, maternally transmitted bacterium that is present in approximately 40% of terrestrial arthropod species. This endosymbiont is often a reproductive parasite but can also provide fitness benefits to its hosts. For instance, the Wolbachia in Drosophila melanogaster, wMel, provides protection against viruses.  This protective effect is currently being applied to fight arboviruses transmission by releasing Wolbachia-transinfected mosquitoes. Titre regulation is a crucial aspect of Wolbachia biology. Higher titres can lead to stronger phenotypes and fidelity of transmission but can have a cost to the host. Since Wolbachia is maternally transmitted, its fitness depends on host fitness, and, therefore, its cost to the host needs to be controlled. Understanding this and other aspects of Wolbachia biology has been hampered by the lack of genetic tools. Here we developed a new forward genetic screen to identify Wolbachia over-proliferative mutant variants. We characterized in detail the phenotype of these two new mutants, wMelPop2 and wMelOctoless. Through genome sequencing we identified the genetic bases of these phenotypes, and expand on the understanding of the role of the Octomom genomic region in the control of Wolbachia proliferation.  Altogether, we demonstrate the feasibility of a novel and unbiased experimental approach to study Wolbachia biology, which can be further adapted to characterize other genetically intractable bacterial endosymbionts.

Moderation: Hugo Barreto (FCG-IGC) 

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