Bacterial Bioluminescence Regulates Expression of a Host Cryptochrome Gene in the Squid-Vibrio Symbiosis

ABSTRACT The symbiosis between the squid Euprymna scolopes and its luminous symbiont, Vibrio fischeri, is characterized by daily transcriptional rhythms in both partners and daily fluctuations in symbiont luminescence. In this study, we sought to determine whether symbionts affect host transcription...

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Autores principales:	Elizabeth A. C. Heath-Heckman, Suzanne M. Peyer, Cheryl A. Whistler, Michael A. Apicella, William E. Goldman, Margaret J. McFall-Ngai
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2013
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/06d3b535e9cc4b8783ca39bd0e011090
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spelling	oai:doaj.org-article:06d3b535e9cc4b8783ca39bd0e0110902021-11-15T15:40:27ZBacterial Bioluminescence Regulates Expression of a Host Cryptochrome Gene in the Squid-Vibrio Symbiosis10.1128/mBio.00167-132150-7511https://doaj.org/article/06d3b535e9cc4b8783ca39bd0e0110902013-05-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00167-13https://doaj.org/toc/2150-7511ABSTRACT The symbiosis between the squid Euprymna scolopes and its luminous symbiont, Vibrio fischeri, is characterized by daily transcriptional rhythms in both partners and daily fluctuations in symbiont luminescence. In this study, we sought to determine whether symbionts affect host transcriptional rhythms. We identified two transcripts in host tissues (E. scolopes cry1 [escry1] and escry2) that encode cryptochromes, proteins that influence circadian rhythms in other systems. Both genes cycled daily in the head of the squid, with a pattern similar to that of other animals, in which expression of certain cry genes is entrained by environmental light. In contrast, escry1 expression cycled in the symbiont-colonized light organ with 8-fold upregulation coincident with the rhythms of bacterial luminescence, which are offset from the day/night light regime. Colonization of the juvenile light organ by symbionts was required for induction of escry1 cycling. Further, analysis with a mutant strain defective in light production showed that symbiont luminescence is essential for cycling of escry1; this defect could be complemented by presentation of exogenous blue light. However, blue-light exposure alone did not induce cycling in nonsymbiotic animals, but addition of molecules of the symbiont cell envelope to light-exposed animals did recover significant cycling activity, showing that light acts in synergy with other symbiont features to induce cycling. While symbiont luminescence may be a character specific to rhythms of the squid-vibrio association, resident microbial partners could similarly influence well-documented daily rhythms in other systems, such as the mammalian gut. IMPORTANCE In mammals, biological rhythms of the intestinal epithelium and the associated mucosal immune system regulate such diverse processes as lipid trafficking and the immune response to pathogens. While these same processes are affected by the diverse resident microbiota, the extent to which these microbial communities control or are controlled by these rhythms has not been addressed. This study provides evidence that the presentation of three bacterial products (lipid A, peptidoglycan monomer, and blue light) is required for cyclic expression of a cryptochrome gene in the symbiotic organ. The finding that bacteria can directly influence the transcription of a gene encoding a protein implicated in the entrainment of circadian rhythms provides the first evidence for the role of bacterial symbionts in influencing, and perhaps driving, peripheral circadian oscillators in the host.Elizabeth A. C. Heath-HeckmanSuzanne M. PeyerCheryl A. WhistlerMichael A. ApicellaWilliam E. GoldmanMargaret J. McFall-NgaiAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 4, Iss 2 (2013)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Elizabeth A. C. Heath-Heckman Suzanne M. Peyer Cheryl A. Whistler Michael A. Apicella William E. Goldman Margaret J. McFall-Ngai Bacterial Bioluminescence Regulates Expression of a Host Cryptochrome Gene in the Squid-Vibrio Symbiosis
description	ABSTRACT The symbiosis between the squid Euprymna scolopes and its luminous symbiont, Vibrio fischeri, is characterized by daily transcriptional rhythms in both partners and daily fluctuations in symbiont luminescence. In this study, we sought to determine whether symbionts affect host transcriptional rhythms. We identified two transcripts in host tissues (E. scolopes cry1 [escry1] and escry2) that encode cryptochromes, proteins that influence circadian rhythms in other systems. Both genes cycled daily in the head of the squid, with a pattern similar to that of other animals, in which expression of certain cry genes is entrained by environmental light. In contrast, escry1 expression cycled in the symbiont-colonized light organ with 8-fold upregulation coincident with the rhythms of bacterial luminescence, which are offset from the day/night light regime. Colonization of the juvenile light organ by symbionts was required for induction of escry1 cycling. Further, analysis with a mutant strain defective in light production showed that symbiont luminescence is essential for cycling of escry1; this defect could be complemented by presentation of exogenous blue light. However, blue-light exposure alone did not induce cycling in nonsymbiotic animals, but addition of molecules of the symbiont cell envelope to light-exposed animals did recover significant cycling activity, showing that light acts in synergy with other symbiont features to induce cycling. While symbiont luminescence may be a character specific to rhythms of the squid-vibrio association, resident microbial partners could similarly influence well-documented daily rhythms in other systems, such as the mammalian gut. IMPORTANCE In mammals, biological rhythms of the intestinal epithelium and the associated mucosal immune system regulate such diverse processes as lipid trafficking and the immune response to pathogens. While these same processes are affected by the diverse resident microbiota, the extent to which these microbial communities control or are controlled by these rhythms has not been addressed. This study provides evidence that the presentation of three bacterial products (lipid A, peptidoglycan monomer, and blue light) is required for cyclic expression of a cryptochrome gene in the symbiotic organ. The finding that bacteria can directly influence the transcription of a gene encoding a protein implicated in the entrainment of circadian rhythms provides the first evidence for the role of bacterial symbionts in influencing, and perhaps driving, peripheral circadian oscillators in the host.
format	article
author	Elizabeth A. C. Heath-Heckman Suzanne M. Peyer Cheryl A. Whistler Michael A. Apicella William E. Goldman Margaret J. McFall-Ngai
author_facet	Elizabeth A. C. Heath-Heckman Suzanne M. Peyer Cheryl A. Whistler Michael A. Apicella William E. Goldman Margaret J. McFall-Ngai
author_sort	Elizabeth A. C. Heath-Heckman
title	Bacterial Bioluminescence Regulates Expression of a Host Cryptochrome Gene in the Squid-Vibrio Symbiosis
title_short	Bacterial Bioluminescence Regulates Expression of a Host Cryptochrome Gene in the Squid-Vibrio Symbiosis
title_full	Bacterial Bioluminescence Regulates Expression of a Host Cryptochrome Gene in the Squid-Vibrio Symbiosis
title_fullStr	Bacterial Bioluminescence Regulates Expression of a Host Cryptochrome Gene in the Squid-Vibrio Symbiosis
title_full_unstemmed	Bacterial Bioluminescence Regulates Expression of a Host Cryptochrome Gene in the Squid-Vibrio Symbiosis
title_sort	bacterial bioluminescence regulates expression of a host cryptochrome gene in the squid-vibrio symbiosis
publisher	American Society for Microbiology
publishDate	2013
url	https://doaj.org/article/06d3b535e9cc4b8783ca39bd0e011090
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Bacterial Bioluminescence Regulates Expression of a Host Cryptochrome Gene in the Squid-Vibrio Symbiosis

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