Relaxation of selective constraints shapes variation of toll-like receptors in a colonial waterbird, the black-headed gull

Nonspecific innate immune response is activated by toll-like receptors (TLRs), which recognize conserved molecular motifs characteristic for a broad spectrum of pathogens. In this study, we examined nucleotide substitution patterns and allelic diversity at five TLR genes in a wild nonpasserine bird,...

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Published in:Immunogenetics
Main Authors: Podlaszczuk, Patrycja, Indykiewicz, Piotr, Markowski, Janusz, Minias, Piotr
Format: Text
Language:English
Published: Springer Berlin Heidelberg 2020
Subjects:
Online Access:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7182547/
http://www.ncbi.nlm.nih.gov/pubmed/31996941
https://doi.org/10.1007/s00251-020-01156-8
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spelling ftpubmed:oai:pubmedcentral.nih.gov:7182547 2023-05-15T18:49:32+02:00 Relaxation of selective constraints shapes variation of toll-like receptors in a colonial waterbird, the black-headed gull Podlaszczuk, Patrycja Indykiewicz, Piotr Markowski, Janusz Minias, Piotr 2020-01-30 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7182547/ http://www.ncbi.nlm.nih.gov/pubmed/31996941 https://doi.org/10.1007/s00251-020-01156-8 en eng Springer Berlin Heidelberg http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7182547/ http://www.ncbi.nlm.nih.gov/pubmed/31996941 http://dx.doi.org/10.1007/s00251-020-01156-8 © The Author(s) 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. CC-BY Original Article Text 2020 ftpubmed https://doi.org/10.1007/s00251-020-01156-8 2020-05-03T00:43:30Z Nonspecific innate immune response is activated by toll-like receptors (TLRs), which recognize conserved molecular motifs characteristic for a broad spectrum of pathogens. In this study, we examined nucleotide substitution patterns and allelic diversity at five TLR genes in a wild nonpasserine bird, the black-headed gull Chroicocephalus ridibundus. We hypothesized that balancing selection can maintain high allelic diversity of TLR genes in the black-headed gull because of its ecological characteristics, coloniality, and migratoriness, which are associated with increased exposure and transmission of pathogens. Although we found moderately high levels of sequence polymorphism (8–49 haplotypes retrieved per locus within a sample of 60 individuals), most of these haplotypes were recorded at low frequencies within our study population. At the same time, we found no convincing evidence for the role of balancing selection in the maintenance of this variation (Tajima’s D < 0.5), and sites with a significant excess of nonsynonymous mutations (dN/dS > 1) were recorded only at two loci (TLR5 and TLR7). This pattern is consistent with relaxation of selective constraints, where most mutations are slightly deleterious and usually removed by purifying selection. No differences in the diversity and nucleotide substitution rates were found between endosomal loci responsible for viral RNA sensing and loci responsible for the recognition of extracellular pathogens. Our study provides the first information on evolutionary mechanisms shaping polymorphism of TLRs in a species from Lari suborder (gulls and allies) and suggests that TLR genes may be poorly responsive to ecological and life-history characteristics of hosts. Text Black-headed Gull Chroicocephalus ridibundus PubMed Central (PMC) Immunogenetics 72 4 251 262
institution Open Polar
collection PubMed Central (PMC)
op_collection_id ftpubmed
language English
topic Original Article
spellingShingle Original Article
Podlaszczuk, Patrycja
Indykiewicz, Piotr
Markowski, Janusz
Minias, Piotr
Relaxation of selective constraints shapes variation of toll-like receptors in a colonial waterbird, the black-headed gull
topic_facet Original Article
description Nonspecific innate immune response is activated by toll-like receptors (TLRs), which recognize conserved molecular motifs characteristic for a broad spectrum of pathogens. In this study, we examined nucleotide substitution patterns and allelic diversity at five TLR genes in a wild nonpasserine bird, the black-headed gull Chroicocephalus ridibundus. We hypothesized that balancing selection can maintain high allelic diversity of TLR genes in the black-headed gull because of its ecological characteristics, coloniality, and migratoriness, which are associated with increased exposure and transmission of pathogens. Although we found moderately high levels of sequence polymorphism (8–49 haplotypes retrieved per locus within a sample of 60 individuals), most of these haplotypes were recorded at low frequencies within our study population. At the same time, we found no convincing evidence for the role of balancing selection in the maintenance of this variation (Tajima’s D < 0.5), and sites with a significant excess of nonsynonymous mutations (dN/dS > 1) were recorded only at two loci (TLR5 and TLR7). This pattern is consistent with relaxation of selective constraints, where most mutations are slightly deleterious and usually removed by purifying selection. No differences in the diversity and nucleotide substitution rates were found between endosomal loci responsible for viral RNA sensing and loci responsible for the recognition of extracellular pathogens. Our study provides the first information on evolutionary mechanisms shaping polymorphism of TLRs in a species from Lari suborder (gulls and allies) and suggests that TLR genes may be poorly responsive to ecological and life-history characteristics of hosts.
format Text
author Podlaszczuk, Patrycja
Indykiewicz, Piotr
Markowski, Janusz
Minias, Piotr
author_facet Podlaszczuk, Patrycja
Indykiewicz, Piotr
Markowski, Janusz
Minias, Piotr
author_sort Podlaszczuk, Patrycja
title Relaxation of selective constraints shapes variation of toll-like receptors in a colonial waterbird, the black-headed gull
title_short Relaxation of selective constraints shapes variation of toll-like receptors in a colonial waterbird, the black-headed gull
title_full Relaxation of selective constraints shapes variation of toll-like receptors in a colonial waterbird, the black-headed gull
title_fullStr Relaxation of selective constraints shapes variation of toll-like receptors in a colonial waterbird, the black-headed gull
title_full_unstemmed Relaxation of selective constraints shapes variation of toll-like receptors in a colonial waterbird, the black-headed gull
title_sort relaxation of selective constraints shapes variation of toll-like receptors in a colonial waterbird, the black-headed gull
publisher Springer Berlin Heidelberg
publishDate 2020
url http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7182547/
http://www.ncbi.nlm.nih.gov/pubmed/31996941
https://doi.org/10.1007/s00251-020-01156-8
genre Black-headed Gull
Chroicocephalus ridibundus
genre_facet Black-headed Gull
Chroicocephalus ridibundus
op_relation http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7182547/
http://www.ncbi.nlm.nih.gov/pubmed/31996941
http://dx.doi.org/10.1007/s00251-020-01156-8
op_rights © The Author(s) 2020
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
op_rightsnorm CC-BY
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