Immune protein orchestrates daily rhythm of squid-bacteria symbiotic relationship

Date:
October 19, 2020
Source:
University of Hawaii at Manoa
Summary:
New research has revealed that, in the mutually beneficial
relationship between with the Hawaiian bobtail squid and the
luminescent bacterium, Vibrio fischeri, an immune protein called
'macrophage migration inhibitory factor' is the maestro of daily
rhythms.



FULL STORY ========================================================================== Nearly every organism hosts a collection of symbiotic microbes --
a microbiome.

It is now recognized that microbiomes are major drivers of health in
all animals, including humans, and that these symbiotic systems often
exhibit strong daily rhythms.


==========================================================================
New research led by University of Hawai'i at Manoa scientists revealed
that, in the mutually beneficial relationship between with the Hawaiian
bobtail squid, Euprymna scolopes, and the luminescent bacterium, Vibrio fischeri, an immune protein called "macrophage migration inhibitory
factor" or "MIF," is the maestro of daily rhythms. This finding, published
in the Proceedings of the National Academy of Sciences, could provide
important clues on factors affecting human microbiome rhythms, as the
MIF protein is also found in abundance in mammalian symbiotic tissues.

To survive, the nocturnal Hawaiian bobtail squid depends on V. fischeri,
which gives it the ability to mimic moonlight on the surface of the ocean
and deceive monk seals and other predators, as it forages for food. The symbiotic bacteria also require nutrition, especially at night when they
are more numerous and their light is required for the squid's camouflage.

The research team, led by Eric Koch, who was a graduate researcher at
the Pacific Biosciences Research Center (PBRC) in the UH Manoa School of
Ocean and Earth Science and Technology (SOEST) at the time of the study, determined the squid regulates production of MIF as a way to control the movement of specialized immune cells, called hemocytes, which provide
chitin for bacteria to feed on.

At night, when the team found MIF was low in the squid's light organ,
hemocytes were allowed into the regions where the bacteria reside and
chitin was delivered. During the day, MIF was very high, which inhibits
the hemocytes from coming into the symbiotic tissues and dumping their
chitin at the wrong time.

This cycling of nutrients has cascading effects on all of the other
rhythms associated with the symbiotic system -- perhaps affecting overall health, development or reproduction.

For nearly three decades, professors Margaret McFall-Ngai and Edward Ruby
at PBRC have used the squid-bacterial symbiosis system to characterize
animal microbiomes.

"We had recognized daily rhythms in the squid-vibrio symbiosis since 1996,
but how the rhythm is controlled was not known," said McFall-Ngai. "This
study brought the whole thing into sharp focus, allowing us to understand
how the rhythm works and how it matures in the animal." Such discoveries
can pave the way for understanding how microbiomes function - - what
they do and how they do it -- in other organisms and environments.

"A recent study of the mammalian, and human, gut microbiome has shown
that MIF is present at high levels and controls the interactions of
the microbes with the host cell," said McFall-Ngai. "As has happened
with other phenomena, such a developmental inducers, the simplicity of
the squid-vibrio system has provided a window into the mechanisms of
symbiosis. Because these mechanisms appear to be highly conserved among
all animals, including humans, understanding how they function promises
to give us the tools to foster healthy people and resilient ecosystems."

========================================================================== Story Source: Materials provided
by University_of_Hawaii_at_Manoa. Original written by Marcie
Grabowski. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Eric J. Koch, Clotilde Bongrand, Brittany D. Bennett, Susannah
Lawhorn,
Silvia Moriano-Gutierrez, Marko Pende, Karim Vadiwala, Hans-Ulrich
Dodt, Florian Raible, William Goldman, Edward G. Ruby, Margaret
McFall-Ngai.

The cytokine MIF controls daily rhythms of symbiont nutrition
in an animal-bacterial association. Proceedings of the National
Academy of Sciences, 2020; 202016864 DOI: 10.1073/pnas.2016864117 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201019155918.htm

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