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Ingham CS, Engl T, Kaltenpoth M. Protection of a defensive symbiont does not constrain the composition of the multifunctional hydrocarbon profile in digger wasps. Biol Lett 2023; 19:20230301. [PMID: 37909057 PMCID: PMC10618855 DOI: 10.1098/rsbl.2023.0301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 10/13/2023] [Indexed: 11/02/2023] Open
Abstract
Hydrocarbons (HCs) fulfil indispensable functions in insects, protecting against desiccation and serving chemical communication. However, the link between composition and function, and the selection pressures shaping HC profiles remain poorly understood. Beewolf digger wasps (Hymenoptera: Crabronidae) use an antennal gland secretion rich in linear unsaturated HCs to form a hydrophobic barrier around their defensive bacterial symbiont, protecting it from brood cell fumigation by toxic egg-produced nitric oxide (NO). Virtually identical HC compositions mediate desiccation protection and prey preservation from moulding in underground beewolf brood cells. It is unknown whether this composition presents an optimized adaptation to all functions, or a compromise due to conflicting selection pressures. Here, we reconstitute the NO barrier with single and binary combinations of synthetic linear saturated and unsaturated HCs, corresponding to HCs found in beewolves. The results show that pure alkanes as well as 3 : 1 mixtures of alkanes and alkenes resembling the composition of beewolf HCs form efficient protective barriers against NO, indicating that protection can be achieved by different mixtures of HCs. Since in vitro assays with symbiont cultures from different beewolf hosts indicate widespread NO sensitivity, HC-mediated protection from NO is likely important across Philanthini wasps. We conclude that HC-mediated protection of the symbiont from NO does not exert a conflicting selection pressure on the multifunctional HC profile of beewolves.
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Affiliation(s)
- Chantal Selina Ingham
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
| | - Tobias Engl
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
- Department of Insect Symbiosis, Max-Planck-Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07745 Jena, Germany
| | - Martin Kaltenpoth
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
- Department of Insect Symbiosis, Max-Planck-Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07745 Jena, Germany
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Ingham CS, Engl T, Matarrita-Carranza B, Vogler P, Huettel B, Wielsch N, Svatoš A, Kaltenpoth M. Host hydrocarbons protect symbiont transmission from a radical host defense. Proc Natl Acad Sci U S A 2023; 120:e2302721120. [PMID: 37487102 PMCID: PMC10400980 DOI: 10.1073/pnas.2302721120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 06/06/2023] [Indexed: 07/26/2023] Open
Abstract
Symbioses with microbes play a pivotal role in the evolutionary success of insects, and can lead to intimate host-symbiont associations. However, how the host maintains a stable symbiosis with its beneficial partners while keeping antagonistic microbes in check remains incompletely understood. Here, we uncover a mechanism by which a host protects its symbiont from the host's own broad-range antimicrobial defense during transmission. Beewolves, a group of solitary digger wasps (Hymenoptera: Crabronidae), provide their brood cells with symbiotic Streptomyces bacteria that are later transferred to the cocoon and protect the offspring from opportunistic pathogens by producing antibiotics. In the brood cell, however, the symbiont-containing secretion is exposed to a toxic burst of nitric oxide (NO) released by the beewolf egg, which effectively kills antagonistic microorganisms. How the symbiont survives this lethal NO burst remained unknown. Here, we report that upon NO exposure in vitro, the symbionts mount a global stress response, but this is insufficient to ensure survival at brood cell-level NO concentrations. Instead, in vivo bioassays demonstrate that the host's antennal gland secretion (AGS) surrounding the symbionts in the brood cell provides an effective diffusion barrier against NO. This physicochemical protection can be reconstituted in vitro by beewolf hydrocarbon extracts and synthetic hydrocarbons, indicating that the host-derived long-chain alkenes and alkanes in the AGS are responsible for shielding the symbionts from NO. Our results reveal how host adaptations can protect a symbiont from host-generated oxidative and nitrosative stress during transmission, thereby efficiently balancing pathogen defense and mutualism maintenance.
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Affiliation(s)
- Chantal Selina Ingham
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University Mainz, Mainz55128, Germany
| | - Tobias Engl
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University Mainz, Mainz55128, Germany
- Department of Insect Symbiosis, Max-Planck-Institute for Chemical Ecology, Jena07745, Germany
| | | | - Paul Vogler
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University Mainz, Mainz55128, Germany
| | - Bruno Huettel
- Max Planck Genome Centre Cologne, Max Planck Institute for Plant Breeding Research, Cologne50829, Germany
| | - Natalie Wielsch
- Research Group Mass Spectrometry/Proteomics, Max-Planck-Institute for Chemical Ecology, Jena07745, Germany
| | - Aleš Svatoš
- Research Group Mass Spectrometry/Proteomics, Max-Planck-Institute for Chemical Ecology, Jena07745, Germany
| | - Martin Kaltenpoth
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University Mainz, Mainz55128, Germany
- Department of Insect Symbiosis, Max-Planck-Institute for Chemical Ecology, Jena07745, Germany
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Pronk LJU, Bakker PAHM, Keel C, Maurhofer M, Flury P. The secret life of plant-beneficial rhizosphere bacteria: insects as alternative hosts. Environ Microbiol 2022; 24:3273-3289. [PMID: 35315557 PMCID: PMC9542179 DOI: 10.1111/1462-2920.15968] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 03/03/2022] [Accepted: 03/04/2022] [Indexed: 12/15/2022]
Abstract
Root-colonizing bacteria have been intensively investigated for their intimate relationship with plants and their manifold plant-beneficial activities. They can inhibit growth and activity of pathogens or induce defence responses. In recent years, evidence has emerged that several plant-beneficial rhizosphere bacteria do not only associate with plants but also with insects. Their relationships with insects range from pathogenic to mutualistic and some rhizobacteria can use insects as vectors for dispersal to new host plants. Thus, the interactions of these bacteria with their environment are even more complex than previously thought and can extend far beyond the rhizosphere. The discovery of this secret life of rhizobacteria represents an exciting new field of research that should link the fields of plant-microbe and insect-microbe interactions. In this review, we provide examples of plant-beneficial rhizosphere bacteria that use insects as alternative hosts, and of potentially rhizosphere-competent insect symbionts. We discuss the bacterial traits that may enable a host-switch between plants and insects and further set the multi-host lifestyle of rhizobacteria into an evolutionary and ecological context. Finally, we identify important open research questions and discuss perspectives on the use of these rhizobacteria in agriculture.
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Affiliation(s)
| | | | - Christoph Keel
- Department of Fundamental MicrobiologyUniversity of LausanneLausanneSwitzerland
| | - Monika Maurhofer
- Plant Pathology, Institute of Integrative BiologyETH ZürichZürichSwitzerland
| | - Pascale Flury
- Crop Protection – Phytopathology, Department of Crop SciencesResearch Institute of Organic Agriculture FiBLFrickSwitzerland
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Goettler W, Kaltenpoth M, McDonald S, Strohm E. Comparative Morphology of the Symbiont Cultivation Glands in the Antennae of Female Digger Wasps of the Genus Philanthus (Hymenoptera: Crabronidae). Front Physiol 2022; 13:815494. [PMID: 35153837 PMCID: PMC8826713 DOI: 10.3389/fphys.2022.815494] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 01/04/2022] [Indexed: 11/13/2022] Open
Abstract
Females of the solitary digger wasp tribe Philanthini, called the beewolves (Hymenoptera, Crabronidae), cultivate strains of symbiotic bacteria that belong to the genus Streptomyces in unique and highly specialized glands in their antennae. The glands consist of large reservoirs that are surrounded by numerous gland cell complexes (class III). The symbionts are cultivated inside the reservoirs and are probably provisioned with nutrients secreted from the surrounding glands and/or sequestered from the hemolymph. The wasp female delivers the bacteria into the subterranean brood cell prior to oviposition. Fully grown larvae take up the bacteria and apply them to their cocoon. There the bacteria produce several antibiotics that protect the wasp offspring against fungus infestation. Hitherto Streptomyces bacteria were detected in the antennae of 38 species of the Philanthini. However, a detailed morphological analysis of the antennal glands is only available for a few species. In order to shed light on the evolutionary history of the association between beewolf wasps and bacteria, we investigated the morphology of the antennal glands of another 14 Philanthus species from the Palearctic, Paleotropic, and Nearctic. We generated 3D-models of the glands based on serial semithin sections and/or micro-CT (μCT). Despite broad similarities in number and structure of antennal glands, the results revealed interspecific differences with regard to overall shape, complexity, and relative size of the reservoirs as well as the number of the surrounding gland cell units. Mapping the morphology of all species studied so far on the phylogeny (that parallels geographical distribution) revealed that related species share similarities in gland morphology, but there are notable differences between lineages. In particular, compared to the North American species the European and African species possess more complex gland structures with a higher number of gland cells. We discuss morphological, ecological, and physiological aspects and provide scenarios for the evolution of the antennal glands of the Philanthini as symbiont cultivation organs.
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Affiliation(s)
- Wolfgang Goettler
- Department of Zoology, University of Regensburg, Regensburg, Germany
| | - Martin Kaltenpoth
- Department of Zoology, University of Regensburg, Regensburg, Germany
- Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Samuel McDonald
- Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland
| | - Erhard Strohm
- Department of Zoology, University of Regensburg, Regensburg, Germany
- *Correspondence: Erhard Strohm,
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Incipient genome erosion and metabolic streamlining for antibiotic production in a defensive symbiont. Proc Natl Acad Sci U S A 2021; 118:2023047118. [PMID: 33883280 PMCID: PMC8092579 DOI: 10.1073/pnas.2023047118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Genome reduction is commonly observed in bacteria of several phyla engaging in obligate nutritional symbioses with insects. In Actinobacteria, however, little is known about the process of genome evolution, despite their importance as prolific producers of antibiotics and their increasingly recognized role as defensive partners of insects and other organisms. Here, we show that “Streptomyces philanthi,” a defensive symbiont of digger wasps, has a G+C-enriched genome in the early stages of erosion, with inactivating mutations in a large proportion of genes, causing dependency on its hosts for certain nutrients, which was validated in axenic symbiont cultures. Additionally, overexpressed catabolic and biosynthetic pathways of the bacteria inside the host indicate host–symbiont metabolic integration for streamlining and control of antibiotic production. Genome erosion is a frequently observed result of relaxed selection in insect nutritional symbionts, but it has rarely been studied in defensive mutualisms. Solitary beewolf wasps harbor an actinobacterial symbiont of the genus Streptomyces that provides protection to the developing offspring against pathogenic microorganisms. Here, we characterized the genomic architecture and functional gene content of this culturable symbiont using genomics, transcriptomics, and proteomics in combination with in vitro assays. Despite retaining a large linear chromosome (7.3 Mb), the wasp symbiont accumulated frameshift mutations in more than a third of its protein-coding genes, indicative of incipient genome erosion. Although many of the frameshifted genes were still expressed, the encoded proteins were not detected, indicating post-transcriptional regulation. Most pseudogenization events affected accessory genes, regulators, and transporters, but “Streptomyces philanthi” also experienced mutations in central metabolic pathways, resulting in auxotrophies for biotin, proline, and arginine that were confirmed experimentally in axenic culture. In contrast to the strong A+T bias in the genomes of most obligate symbionts, we observed a significant G+C enrichment in regions likely experiencing reduced selection. Differential expression analyses revealed that—compared to in vitro symbiont cultures—“S. philanthi” in beewolf antennae showed overexpression of genes for antibiotic biosynthesis, the uptake of host-provided nutrients and the metabolism of building blocks required for antibiotic production. Our results show unusual traits in the early stage of genome erosion in a defensive symbiont and suggest tight integration of host–symbiont metabolic pathways that effectively grants the host control over the antimicrobial activity of its bacterial partner.
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Masson F, Lemaitre B. Growing Ungrowable Bacteria: Overview and Perspectives on Insect Symbiont Culturability. Microbiol Mol Biol Rev 2020; 84:e00089-20. [PMID: 33177190 PMCID: PMC7667007 DOI: 10.1128/mmbr.00089-20] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Insects are often involved in endosymbiosis, that is, the housing of symbiotic microbes within their tissues or within their cells. Endosymbionts are a major driving force in insects' evolution, because they dramatically affect their host physiology and allow them to adapt to new niches, for example, by complementing their diet or by protecting them against pathogens. Endosymbiotic bacteria are, however, fastidious and therefore difficult to manipulate outside of their hosts, especially intracellular species. The coevolution between hosts and endosymbionts leads to alterations in the genomes of endosymbionts, limiting their ability to cope with changing environments. Consequently, few insect endosymbionts are culturable in vitro and genetically tractable, making functional genetics studies impracticable on most endosymbiotic bacteria. However, recently, major progress has been made in manipulating several intracellular endosymbiont species in vitro, leading to astonishing discoveries on their physiology and the way they interact with their host. This review establishes a comprehensive picture of the in vitro tractability of insect endosymbiotic bacteria and addresses the reason why most species are not culturable. By compiling and discussing the latest developments in the design of custom media and genetic manipulation protocols, it aims at providing new leads to expand the range of tractable endosymbionts and foster genetic research on these models.
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Affiliation(s)
- Florent Masson
- Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Bruno Lemaitre
- Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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8
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Herbrík A, Corretto E, Chroňáková A, Langhansová H, Petrásková P, Hrdý J, Čihák M, Krištůfek V, Bobek J, Petříček M, Petříčková K. A Human Lung-Associated Streptomyces sp. TR1341 Produces Various Secondary Metabolites Responsible for Virulence, Cytotoxicity and Modulation of Immune Response. Front Microbiol 2020; 10:3028. [PMID: 32010093 PMCID: PMC6978741 DOI: 10.3389/fmicb.2019.03028] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 12/17/2019] [Indexed: 12/16/2022] Open
Abstract
Streptomycetes, typical soil dwellers, can be detected as common colonizers of human bodies, especially the skin, the respiratory tract, the guts and the genital tract using molecular techniques. However, their clinical manifestations and isolations are rare. Recently they were discussed as possible "coaches" of the human immune system in connection with certain immune disorders and cancer. This work aimed for the characterization and evaluation of genetic adaptations of a human-associated strain Streptomyces sp. TR1341. The strain was isolated from sputum of a senior male patient with a history of lung and kidney TB, recurrent respiratory infections and COPD. It manifested remarkably broad biological activities (antibacterial, antifungal, beta-hemolytic, etc.). We found that, by producing specific secondary metabolites, it is able to modulate host immune responses and the niche itself, which increase its chances for long-term survival in the human tissue. The work shows possible adaptations or predispositions of formerly soil microorganism to survive in human tissue successfully. The strain produces two structural groups of cytotoxic compounds: 28-carbon cytolytic polyenes of the filipin type and actinomycin X2. Additionally, we summarize and present data about streptomycete-related human infections known so far.
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Affiliation(s)
- Andrej Herbrík
- Institute of Immunology and Microbiology, 1st Faculty of Medicine, Charles University, Prague, Czechia
| | - Erika Corretto
- Institute of Soil Biology, Biology Centre Academy of Sciences of the Czech Republic, České Budějovice, Czechia
| | - Alica Chroňáková
- Institute of Soil Biology, Biology Centre Academy of Sciences of the Czech Republic, České Budějovice, Czechia
| | - Helena Langhansová
- Faculty of Science, University of South Bohemia, České Budějovice, Czechia
| | - Petra Petrásková
- Institute of Immunology and Microbiology, 1st Faculty of Medicine, Charles University, Prague, Czechia
| | - Jiří Hrdý
- Institute of Immunology and Microbiology, 1st Faculty of Medicine, Charles University, Prague, Czechia
| | - Matouš Čihák
- Institute of Immunology and Microbiology, 1st Faculty of Medicine, Charles University, Prague, Czechia
| | - Václav Krištůfek
- Institute of Soil Biology, Biology Centre Academy of Sciences of the Czech Republic, České Budějovice, Czechia
| | - Jan Bobek
- Institute of Immunology and Microbiology, 1st Faculty of Medicine, Charles University, Prague, Czechia.,Department of Chemistry, Faculty of Science, Jan Evangelista Purkyně University in Ústí nad Labem, Ústí nad Labem, Czechia
| | - Miroslav Petříček
- Institute of Immunology and Microbiology, 1st Faculty of Medicine, Charles University, Prague, Czechia
| | - Kateřina Petříčková
- Institute of Immunology and Microbiology, 1st Faculty of Medicine, Charles University, Prague, Czechia.,Faculty of Science, University of South Bohemia, České Budějovice, Czechia
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Evolutionary stability of antibiotic protection in a defensive symbiosis. Proc Natl Acad Sci U S A 2018; 115:E2020-E2029. [PMID: 29444867 DOI: 10.1073/pnas.1719797115] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The increasing resistance of human pathogens severely limits the efficacy of antibiotics in medicine, yet many animals, including solitary beewolf wasps, successfully engage in defensive alliances with antibiotic-producing bacteria for millions of years. Here, we report on the in situ production of 49 derivatives belonging to three antibiotic compound classes (45 piericidin derivatives, 3 streptochlorin derivatives, and nigericin) by the symbionts of 25 beewolf host species and subspecies, spanning 68 million years of evolution. Despite a high degree of qualitative stability in the antibiotic mixture, we found consistent quantitative differences between species and across geographic localities, presumably reflecting adaptations to combat local pathogen communities. Antimicrobial bioassays with the three main components and in silico predictions based on the structure and specificity in polyketide synthase domains of the piericidin biosynthesis gene cluster yield insights into the mechanistic basis and ecoevolutionary implications of producing a complex mixture of antimicrobial compounds in a natural setting.
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Hill P, Heberlig GW, Boddy CN. Sampling Terrestrial Environments for Bacterial Polyketides. Molecules 2017; 22:E707. [PMID: 28468277 PMCID: PMC6154731 DOI: 10.3390/molecules22050707] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Revised: 04/14/2017] [Accepted: 04/18/2017] [Indexed: 12/17/2022] Open
Abstract
Bacterial polyketides are highly biologically active molecules that are frequently used as drugs, particularly as antibiotics and anticancer agents, thus the discovery of new polyketides is of major interest. Since the 1980s discovery of polyketides has slowed dramatically due in large part to the repeated rediscovery of known compounds. While recent scientific and technical advances have improved our ability to discover new polyketides, one key area has been under addressed, namely the distribution of polyketide-producing bacteria in the environment. Identifying environments where producing bacteria are abundant and diverse should improve our ability to discover (bioprospect) new polyketides. This review summarizes for the bioprospector the state-of-the-field in terrestrial microbial ecology. It provides insight into the scientific and technical challenges limiting the application of microbial ecology discoveries for bioprospecting and summarizes key developments in the field that will enable more effective bioprospecting. The major recent efforts by researchers to sample new environments for polyketide discovery is also reviewed and key emerging environments such as insect associated bacteria, desert soils, disease suppressive soils, and caves are highlighted. Finally strategies for taking and characterizing terrestrial samples to help maximize discovery efforts are proposed and the inclusion of non-actinomycetal bacteria in any terrestrial discovery strategy is recommended.
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Affiliation(s)
- Patrick Hill
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada.
| | - Graham W Heberlig
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada.
| | - Christopher N Boddy
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada.
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada.
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Chu L, Xu X, Ran Y. Primary cutaneous nocardiosis caused by Nocardia brasiliensis
following a wasp sting. Clin Exp Dermatol 2017; 42:416-419. [PMID: 28397286 DOI: 10.1111/ced.13086] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/02/2016] [Indexed: 02/05/2023]
Affiliation(s)
- L. Chu
- Department of Dermatology; West China Hospital; Sichuan University No. 37 of Guo Xue Xiang; Chengdu Sichuan China
| | - X. Xu
- Department of Dermatology; West China Hospital; Sichuan University No. 37 of Guo Xue Xiang; Chengdu Sichuan China
| | - Y. Ran
- Department of Dermatology; West China Hospital; Sichuan University No. 37 of Guo Xue Xiang; Chengdu Sichuan China
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Hillman K, Goodrich-Blair H. Are you my symbiont? Microbial polymorphic toxins and antimicrobial compounds as honest signals of beneficial symbiotic defensive traits. Curr Opin Microbiol 2016; 31:184-190. [DOI: 10.1016/j.mib.2016.04.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 04/11/2016] [Accepted: 04/13/2016] [Indexed: 11/28/2022]
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Kaltenpoth M, Roeser-Mueller K, Stubblefield JW, Seger J, Strohm E. Biogeography of a defensive symbiosis. Commun Integr Biol 2015; 7:e993265. [PMID: 26479018 PMCID: PMC4594253 DOI: 10.4161/19420889.2014.993265] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 10/27/2014] [Accepted: 10/28/2014] [Indexed: 11/29/2022] Open
Abstract
Mutualistic microorganisms play important roles in nutrition, reproduction and defense of many insects, yet the factors contributing to their maintenance and dispersal remain unknown in most cases. Theory suggests that collaboration can be maintained by repeated interaction of the same partners (partner fidelity) or by selective discrimination against non-cooperative partners (partner choice). In the defensive mutualism between solitary beewolf wasps and their antibiotic-producing Streptomyces bacteria, partner choice by host control of vertical symbiont transmission reinforces partner fidelity and has helped to maintain this highly specific association since it originated in the late Cretaceous. However, co-phylogenetic and biogeographic analyses suggest that there has also been considerable horizontal transmission of the symbionts. While the beewolves clearly have a paleotropic or palearctic origin, with later colonization of the nearctic and neotropics via Beringia and the Aves ridge, respectively, the bacteria show only weak geographical clustering, implying global dispersal or vicariance within the confines of an otherwise apparently exclusive symbiotic relationship. We discuss several hypotheses that may explain these patterns. Future studies investigating the occurrence of beewolf symbionts in the environment could yield broadly applicable insights into the relative impact of animal-vectored and free-living dispersal on the distribution of microorganisms in nature.
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Affiliation(s)
- Martin Kaltenpoth
- Max Planck Institute for Chemical Ecology; Insect Symbiosis Research Group ; Jena, Germany
| | | | | | - Jon Seger
- Department of Biology; University of Utah ; Salt Lake City, UT USA
| | - Erhard Strohm
- University of Regensburg; Department for Zoology ; Regensburg, Germany
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