PMID:23549919

Citation	Heath-Heckman, EA, Peyer, SM, Whistler, CA, Apicella, MA, Goldman, WE and McFall-Ngai, MJ (2013) Bacterial bioluminescence regulates expression of a host cryptochrome gene in the squid-Vibrio symbiosis. MBio 4
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.
Links	PubMed PMC3622930 Online version:10.1128/mBio.00167-13
Keywords	Aliivibrio fischeri/metabolism; Aliivibrio fischeri/physiology; Animals; Cryptochromes/biosynthesis; Decapodiformes/enzymology; Decapodiformes/genetics; Decapodiformes/microbiology; Gene Expression Regulation/radiation effects; Luminescence; Symbiosis
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
VIBF1:Q5E6P1		GO:0006355: regulation of transcription, DNA-dependent	ECO:0000315:		P		Figure 7a shows the effects of fur on a number of transcriptional factors.	complete CACAO 8668
VIBF1:Q5E6P1		GO:0003677: DNA binding	ECO:0000247:	PMID:16109747	F		Figure 6 shows integration points into target genome by fur.	complete CACAO 8669

References

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