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Mazorra-Alonso M, Peralta-Sánchez JM, Martín-Vivaldi M, Martínez-Bueno M, Gómez RN, Soler JJ. Volatiles of symbiotic bacterial origin explain ectoparasitism and fledging success of hoopoes. Anim Microbiome 2024; 6:26. [PMID: 38725090 PMCID: PMC11084096 DOI: 10.1186/s42523-024-00312-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Accepted: 04/19/2024] [Indexed: 05/12/2024] Open
Abstract
BACKGROUND Some parasites use olfactory cues to detect their hosts and, since bacterial symbionts are partially responsible for animal odours, they could influence host parasitism. By autoclaving nest materials of hoopoe (Upupa epops) nests before reproduction started, we explored the hypothetical links between host-associated bacteria, volatiles and parasitism. During the nestling stage, we (i) estimated the level of ectoparasitism by chewing lice (Suborder Mallophaga) in adult hoopoe females and by Carnus haemapterus flies in nestlings, and (ii) characterized microbial communities and volatile profiles of nest environments (nest material and nest cavity, respectively) and uropygial secretions. RESULTS Experimental nests had less diverse bacterial communities and more diverse volatile profiles than control nests, while occupants experienced lower intensity of parasitism in experimental than in control nests. The experiment also affected beta diversity of the microbial communities of nest material and of the volatiles of the nestling uropygial secretions. Moreover, microbial communities of uropygial secretions and of nest materials covaried with their volatile profiles, while the volatile profile of the bird secretions explained nest volatile profile. Finally, a subset of the volatiles and bacteria detected in the nest material and uropygial secretions were associated with the ectoparasitism intensity of both adult females and nestlings, and with fledging success. CONCLUSIONS These results show that a component of animal odours is linked with the microbial communities of the host and its reproductive environment, and emphasize that the associations between bacteria, ectoparasitism and reproductive success are partially mediated by volatiles of bacterial origin. Future work should focus on mechanisms underlying the detected patterns.
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Affiliation(s)
- Mónica Mazorra-Alonso
- Departamento de Ecología Funcional y Evolutiva, Estación Experimental de Zonas Áridas (CSIC), Almería, Spain
| | | | - Manuel Martín-Vivaldi
- Departamento de Zoología, Universidad de Granada, Granada, Spain
- Unidad Asociada (CSIC): Coevolución: Cucos, Hospedadores y Bacterias Simbiontes. Universidad de Granada, Granada, Spain
| | - Manuel Martínez-Bueno
- Departamento de Microbiología, Universidad de Granada, Granada, Spain
- Unidad Asociada (CSIC): Coevolución: Cucos, Hospedadores y Bacterias Simbiontes. Universidad de Granada, Granada, Spain
| | - Rafael Núñez Gómez
- Servicio de Instrumentación Científica, Estación Experimental del Zaidín (CSIC), Granada, Spain
| | - Juan José Soler
- Departamento de Ecología Funcional y Evolutiva, Estación Experimental de Zonas Áridas (CSIC), Almería, Spain.
- Unidad Asociada (CSIC): Coevolución: Cucos, Hospedadores y Bacterias Simbiontes. Universidad de Granada, Granada, Spain.
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Tebbe J, Havenstein K, Forcada J, Tiedemann R, Caspers B, Hoffman JI. No evidence for a role of MHC class II genotype in the chemical encoding of heterozygosity and relatedness in Antarctic fur seals. Proc Biol Sci 2024; 291:20232519. [PMID: 38503331 PMCID: PMC10950461 DOI: 10.1098/rspb.2023.2519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 02/22/2024] [Indexed: 03/21/2024] Open
Abstract
Despite decades of research, surprisingly little is known about the mechanism(s) by which an individual's genotype is encoded in odour. Many studies have focused on the role of the major histocompatibility complex (MHC) owing to its importance for survival and mate choice. However, the salience of MHC-mediated odours compared to chemicals influenced by the rest of the genome remains unclear, especially in wild populations where it is challenging to quantify and control for the effects of the genomic background. We addressed this issue in Antarctic fur seals by analysing skin swabs together with full-length MHC DQB II exon 2 sequences and data from 41 genome-wide distributed microsatellites. We did not find any effects of MHC relatedness on chemical similarity and there was also no relationship between MHC heterozygosity and chemical diversity. However, multilocus heterozygosity showed a significant positive association with chemical diversity, even after controlling for MHC heterozygosity. Our results appear to rule out a dominant role of the MHC in the chemical encoding of genetic information in a wild vertebrate population and highlight the need for genome-wide approaches to elucidate the mechanism(s) and specific genes underlying genotype-odour associations.
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Affiliation(s)
- Jonas Tebbe
- Department of Evolutionary Population Genetics, Faculty of Biology, Bielefeld University, 33615 Bielefeld, Germany
- Department of Behavioural Ecology, Bielefeld University, 33501 Bielefeld, Germany
- Department of Animal Behaviour, Bielefeld University, 33501 Bielefeld, Germany
| | - Katja Havenstein
- Unit of Evolutionary Biology / Systematic Zoology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
| | - Jaume Forcada
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 OET, UK
| | - Ralph Tiedemann
- Unit of Evolutionary Biology / Systematic Zoology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
| | - Barbara Caspers
- Department of Behavioural Ecology, Bielefeld University, 33501 Bielefeld, Germany
- Joint Institute for Individualisation in a Changing Environment (JICE), Bielefeld University and University of Münster, Bielefeld, Germany
| | - Joseph I. Hoffman
- Department of Evolutionary Population Genetics, Faculty of Biology, Bielefeld University, 33615 Bielefeld, Germany
- Department of Animal Behaviour, Bielefeld University, 33501 Bielefeld, Germany
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 OET, UK
- Joint Institute for Individualisation in a Changing Environment (JICE), Bielefeld University and University of Münster, Bielefeld, Germany
- Center for Biotechnology (CeBiTec), Faculty of Biology, Bielefeld University, 33615 Bielefeld, Germany
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Rojas CA, Marks SL, Borras E, Lesea H, McCartney MM, Coil D, Davis CE, Eisen JA. Characterization of the microbiome and volatile compounds in anal gland secretions from domestic cats (Felis catus) using metagenomics and metabolomics. RESEARCH SQUARE 2023:rs.3.rs-2883555. [PMID: 37214811 PMCID: PMC10197813 DOI: 10.21203/rs.3.rs-2883555/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Animals rely on volatile chemical compounds for their communication and behavior. Many of these compounds are sequestered in endocrine and exocrine glands and are synthesized by anaerobic microbes. While the volatile organic compound (VOC) or microbiome composition of glandular secretions has been investigated in several mammalian species, few have linked specific bacterial taxa to the production of volatiles or to specific microbial gene pathways. Here, we use metagenomic sequencing, mass-spectrometry based metabolomics, and culturing to profile the microbial and volatile chemical constituents of anal gland secretions in twenty-three domestic cats (Felis catus), in attempts to identify organisms potentially involved in host odor production. We found that the anal gland microbiome was dominated by bacteria in the genera Corynebacterium, Bacteroides, Proteus, Lactobacillus, and Streptococcus, and showed striking variation among individual cats. Microbiome profiles also varied with host age and obesity. Metabolites such as fatty-acids, ketones, aldehydes and alcohols were detected in glandular secretions. Overall, microbiome and metabolome profiles were modestly correlated (r=0.17), indicating that a relationship exists between the bacteria in the gland and the metabolites produced in the gland. Functional analyses revealed the presence of genes predicted to code for enzymes involved in VOC metabolism such as dehydrogenases, reductases, and decarboxylases. From metagenomic data, we generated 85 high-quality metagenome assembled genomes (MAGs). Of these, four were inferred to have high relative abundance in metagenome profiles and had close relatives that were recovered as cultured isolates. These four MAGs were classified as Corynebacterium frankenforstense, Proteus mirabilis, Lactobacillus johnsonii, and Bacteroides fragilis. They represent strong candidates for further investigation of the mechanisms of volatile synthesis and scent production in the mammalian anal gland.
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Grieves LA, Bottini CLJ, Gloor GB, MacDougall-Shackleton EA. Uropygial gland microbiota differ between free-living and captive songbirds. Sci Rep 2022; 12:18283. [PMID: 36316352 PMCID: PMC9622905 DOI: 10.1038/s41598-022-22425-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 10/14/2022] [Indexed: 11/05/2022] Open
Abstract
Symbiotic microbes can affect host behavior and fitness. Gut microbiota have received the most study, with less attention to other important microbial communities like those of scent-producing glands such as mammalian anal glands and the avian uropygial gland. However, mounting evidence suggests that microbes inhabiting scent-producing glands play an important role in animal behavior by contributing to variation in chemical signals. Free-living and captive conditions typically differ in social environment, food diversity and availability, disease exposure, and other factors-all of which can translate into differences in gut microbiota. However, whether extrinsic factors such as captivity alter microbial communities in scent glands remains an open question. We compared the uropygial gland microbiota of free-living and captive song sparrows (Melospiza melodia) and tested for an effect of dietary manipulations on the gland microbiota of captive birds. As predicted, the uropygial gland microbiota was significantly different between free-living and captive birds. Surprisingly, microbial diversity was higher in captive than free-living birds, and we found no effect of dietary treatments on captive bird microbiota. Identifying the specific factors responsible for microbial differences among groups and determining whether changes in symbiotic microbiota alter behavior and fitness are important next steps in this field.
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Affiliation(s)
- L. A. Grieves
- grid.39381.300000 0004 1936 8884Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON N6A 5B7 Canada ,grid.25073.330000 0004 1936 8227Present Address: Department of Biology, McMaster University, 1280 Main St. W, Hamilton, ON L8S 3L8 Canada
| | - C. L. J. Bottini
- grid.39381.300000 0004 1936 8884Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON N6A 5B7 Canada
| | - G. B. Gloor
- grid.39381.300000 0004 1936 8884Department of Biochemistry, The University of Western Ontario, 1151 Richmond St., London, ON N6A 5C1 Canada
| | - E. A. MacDougall-Shackleton
- grid.39381.300000 0004 1936 8884Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON N6A 5B7 Canada
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A Review of Suggested Mechanisms of MHC Odor Signaling. BIOLOGY 2022; 11:biology11081187. [PMID: 36009814 PMCID: PMC9405088 DOI: 10.3390/biology11081187] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/26/2022] [Accepted: 08/04/2022] [Indexed: 11/23/2022]
Abstract
Simple Summary Immune genes of the vertebrate MHC vary among individuals. Each individual collection is optimally diverse to provide resistance against some infectious diseases but not too diverse to cause autoimmune diseases. MHC-dependent mate choice aims for optimally complementary MHC alleles. Each potential partner signals through body odor his/her MHC alleles. Identifying the signal molecules was a long-lasting puzzle solved only recently after many deviations as described. Commensal microbiota which are controlled by the individual MHC genes differ among individuals. They were suspected repeatedly to provide the signal, though mice raised germ-free could still smell MHC genes. Carrier hypotheses came in various versions, centered around the specificity of each MHC molecule for binding peptides from diseases, shown to T lymphocytes to induce the immune response. Volatiles of various origins were suggested to fill the place of the peptide and thus reflect the identity of the MHC molecule. Finally, the bound peptides themselves were identified as the sought info-chemicals. Synthesized peptides affect mate choice as predicted. Specific olfactory neurons were shown to react to these peptides but only to the anchors that define the binding specificity. Even eggs choose sperm to produce offspring with optimal MHC, though the signaling pathway needs further research. Abstract Although an individual’s mix of MHC immune genes determines its resistance, finding MHC-dependent mate choice occurred by accident in inbred mice. Inbred mice prefer MHC dissimilar mates, even when the choice was restricted to urine. It took decades to find the info-chemicals, which have to be as polymorphic as the MHC. Microbiota were suggested repeatedly as the origin of the odor signal though germ-free mice maintained normal preference. Different versions of the ‘carrier hypothesis’ suggested MHC molecules carry volatiles after the bound peptide is released. Theory predicted an optimal individual MHC diversity to maximize resistance. The optimally complementary mate should be and is preferred as several studies show. Thus, the odor signal needs to transmit the exact information of the sender’s MHC alleles, as do MHC ligand peptides but not microbiota. The ‘MHC peptide hypothesis’ assumes that olfactory perception of the peptide ligand provides information about the MHC protein in a key-lock fashion. Olfactory neurons react only to the anchors of synthesized MHC peptides, which reflect the binding MHC molecule’s identity. Synthesized peptides supplemented to a male’s signal affect choice in the predicted way, however, not when anchors are mutated. Also, the human brain detects smelled synthesized self-peptides as such. After mate choice, the lottery of meiosis of randomly paired oocyte and sperm haplotypes would often produce MHC non-optimal offspring. In sticklebacks, eggs select MHC-compatible sperm, thus prefer the best combination close to the population optimum.
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Jennings SL, Hoover BA, Wa Sin SY, Ebeler SE. Feather chemicals contain information about the major histocompatibility complex in a highly scented seabird. Proc Biol Sci 2022; 289:20220567. [PMID: 35611538 PMCID: PMC9130785 DOI: 10.1098/rspb.2022.0567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Mate choice informed by the immune genes of the major histocompatibility complex (MHC) may provide fitness benefits including offspring with increased immunocompetence. Olfactory cues are considered the primary mechanism organisms use to evaluate the MHC of potential mates, yet this idea has received limited attention in birds. Motivated by a finding of MHC-dependent mate choice in the Leach's storm-petrel (Oceanodroma leucorhoa), we examined whether the chemical profiles of this highly scented seabird contain information about MHC genes. Whereas previous studies in birds examined non-volatile compounds, we used gas chromatography-mass spectrometry to measure the volatile compounds emitted from feathers that potentially serve as olfactory infochemicals about MHC and coupled this with locus-specific genotyping of MHC IIB genes. We found that feather chemicals reflected individual MHC diversity through interactions with sex and breeding status. Furthermore, similarity in MHC genotype was correlated with similarity in chemical profiles within female-female and male-female dyads. We provide the first evidence that volatile chemicals from bird feathers can encode information about the MHC. Our findings suggest that olfaction likely aids MHC-based mate choice in this species and highlight a role for chemicals in mediating genetic mate choice in birds where this mode of communication has been largely overlooked.
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Affiliation(s)
- Sarah L. Jennings
- Graduate Group in Ecology, University of California Davis, Davis CA 95616, USA
| | - Brian A. Hoover
- Graduate Group in Ecology, University of California Davis, Davis CA 95616, USA,Schmid College of Science and Technology, Chapman University, Orange, CA 92886, USA
| | - Simon Yung Wa Sin
- School of Biological Sciences, The University of Hong Kong, Pok Fu Lam Road, Hong Kong SAR
| | - Susan E. Ebeler
- Graduate Group in Ecology, University of California Davis, Davis CA 95616, USA,Department of Viticulture and Enology, University of California Davis, Davis CA 95616, USA
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