Researchers have found there is a bacterial protein “key” that allows the Hawaiian bobtail squid to develop a healthy body and its bioluminescent “glow.” While researchers have long known the squid recruits Vibrio fischeri from the ocean to provide bioluminescent camouflage, a University of Hawaiʻi
at Mānoa revealed that the benefit of the partnership extends far beyond light-production: the bacteria were found to play a vital role in the healthy development of the squid.

“Our recent work revealed that in order to develop properly, the squid host requires a protein provided by its bacterial symbiont,” said Jill (Kuwabara) Smith, lead author of the study, who was a postdoctoral researcher at the (PBRC) in the 糖心Vlog官方 Mānoa (SOEST) at the time of this research. “This was very surprising, but given that the work we do with this symbiosis model is always pioneering, just about every new finding is a surprise!”

Most bacteria release tiny, protein-filled “delivery packets” from their surfaces. Researchers previously knew that the Vibrio fischeri bacteria used a specific protein in these packets, called SypC, to start its relationship with the squid.

“Once the bacteria and its vesicles are inside the squid host, the new research found that the SypC assumes a new function—it prompts development of the light-organ itself,” Smith shared.

Tracking a rare but important protein

To test this, the team tracked SypC by making it glow under a microscope. They found that without this single bacterial protein, the squid鈥檚 body did not develop correctly. Interestingly, the squid’s own immune cells—which usually kill germs—actually helped pick up these bacterial packets and carry them to the exact spot where the light organ needed to grow. Without SypC, the expression of 138 different genes in the squid was altered.

“In addition to contributing light-production capabilities, Vibrio fischeri are prompting the squid鈥檚 development of organs and healthy expression of genes that are involved in a wide range of functions,” said Smith.

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Luminescent bacteria that live harmoniously inside the Hawaiian bobtail squid’s light organ actually change the gene expression in other organs of their squid host. That startling finding was revealed in a new study published in by researchers in the (SOEST) at the .

Bacteria have been driving animal biology since the origin of animals, and most animal-bacteria associations benefit the lives of their host organism in a relationship called symbiosis. Understanding the interdependence of microbes and other organisms, including humans, is the frontier of medicine and environmental health.

The Hawaiian bobtail squid is active at night in the shallow waters of the Hawaiian archipelago. It emits from its body the light produced by its bacterial partner to camouflage against moonlight and starlight. The animal modulates the bioluminescence output of its microbes in response to variations in environmental light, such as from cloud cover. This behavior is believed to be controlled through feedback between the eye and light organ.

How far does the microbes’ influence go?

For nearly three decades, the laboratories of director Margaret McFall-Ngai and researcher Edward Ruby at the (PBRC) in SOEST have used the Hawaiian bobtail squid and its light-producing symbiont, Vibrio fischeri, as a model biological system to unravel the details of this mysterious and vital relationship.

• Related: More 糖心Vlog官方 News stories on the Hawaiian bobtail squid research

Silvia Moriano-Gutierrez, graduate student in PBRC with McFall-Ngai, asked the question: Does Vibriocolonization of the Hawaiian bobtail squid light organ influence gene expression in other parts of the squid’s body?

“My first surprise was that the most significant driver of gene expression in the light organ is not the presence of the bacteria themselves, but rather the presence of bacteria that make light,” said Moriano-Gutierrez. “In other words, light production by the symbionts was a more significant driver of host gene expression.”

Doing their job of producing bioluminescence

The fact that the gene expression responds more to light production than to bacterial presence underscores the importance to the animal of the bacteria doing their job of producing bioluminescence.

Next, the researchers assessed how the varying conditions affected tissues remote from the symbionts, that is, the eye and gill. Both of these organs responded to these conditions with their own unique gene expression signature. The gills responded similarly to the presence of both wild-type and dark mutants.

“However, the next big surprise was that, while the eye responded with robust changes in the expression of dozens of genes when the light organ is colonized by wild-type, when colonized by the dark mutant, no genes changed their regulation in the eye,” said Ruby. “The data support the idea that coordination between eye and light organ is important for the use of light in the animal’s behavior.”

With future research, the team will address which other possible features of the symbiont trigger such responses in host tissues, and how those signals get to remote tissues, in an effort to understand the mechanism underlying the complexity of host-microbe communication.

For the , see the SOEST website.

—By Marcie Grabowski

, professor and director of the (PBRC) in the at the , has been selected to receive a MERIT award of more than $5 million from the National Institutes of Health (NIH).

MERIT or Method to Extend Research In Time awards have been offered since 1986 to “distinctly superior” investigators who have demonstrated high levels of competence and productivity in previous research efforts and “who are highly likely to continue to perform in an outstanding manner.” The awards, which can be extended for up to 10 years via a non-competitive renewal process after the first five years, are designed to give scientists long-term support, without the burden of constantly devoting time and staff resources to applying for new grants to fund their research.

For nearly three decades, McFall-Ngai and PBRC Researcher have used the Hawaiian bobtail squid and its single bacterial symbiont, Vibrio fischeri, as a model biological system to characterize animal microbiomes. They have investigated the process by which an appropriate symbiont species is recruited into a host animal’s microbiome at the exclusion of all other bacteria, and discovered bacteria affecting animal development and bacterial partners driving circadian (daily) rhythms of their host.

“With this new award, Ned, who is the co-investigator on the grant, and I will continue to use marine animals to define the ‘rules’ that govern the molecular and biochemical ‘conversation’ that mediates the establishment and maintenance of an animal symbiosis with gram-negative bacteria (a classification of bacteria that can cause many types of infections),” said McFall-Ngai.

Award-winning investigation of bacteria

Humans, as with all other animals, have many symbiotic, or friendly, bacteria living inside and on our bodies. These associations typically involve trillions of bacteria.

“Deciphering the molecular language between the host-symbiont partners is very challenging,” said McFall-Ngai. “The marine animal with which we work has a binary association, that is, one bacterial species living with a single host animal. As such, it’s like dropping into a conversation with two people, rather than dropping into a celebration that has millions of people.”

Since bacteria have been driving animal biology since the origin of animals, it is not surprising that the basis of interactions of animals with bacteria is conserved across the evolutionary trajectory of animals, making this research relevant to human biology, as well.

McFall-Ngai and Ruby were the first to show that bacteria can drive animal development and they do so by signaling with their surface molecules. A few years later mammalian biologists built on this finding to determine that gram-negative bacteria drive maturation of the gut-associated lymphoid tissue, using the exact same bacterial molecules.

“Our goal is to define the basic cell, biochemical and molecular underpinnings and provide insights for human biologists,” said McFall-Ngai.

More on MERIT awards

MERIT awardees are nominated by the funding NIH institute from a large pool of competing award recipients and then endorsed by an institutes’ advisory council. Less than 5 percent of NIH-funded investigators are selected to receive MERIT awards.

• More about McFall-Ngai: Microbiology expert wins $1M, plans to transform biology education,
  December 13, 2017
• 糖心Vlog官方鈥檚 only female NAS member reveals how animals select good microbes, August 28, 2017
• Native squid and its bacterium may help human and environmental health, February 5, 2017

“This prestigious MERIT award is NIH‘s acknowledgement of research excellence being sustained by Margaret and Ned over the years. It is one of the highest forms of recognition by a federal funding agency,” said School of Ocean and Earth Science and Technology Dean .

“There is something wonderful about not having to stress over a renewal in 5 years,” said McFall-Ngai. “As long as we are as productive as we have been, the grant will continue without having to submit a competitive renewal. We have been contributing all of our careers to this area and we are gratified that NIH has recognized our work in this way.”

McFall-Ngai’s award will run until January 31, 2028.

—By Marcie Grabowski

, professor and director of the , is the only woman at the University of Hawaiʻi who is a member of the . In her , commemorating her induction into one of the country鈥檚 most distinguished scientific groups, she and a team of researchers reveal a newly discovered mechanism by which organisms select beneficial microbes and reject harmful ones.

The internal microbial communities, or consortia, of mammals, such as humans, are complex in that they require many bacterial types for healthy function. Tissues in the respiratory system, the Fallopian tubes, and the Eustachian tubes are lined with cilia—microscopic hair-like structures that extend out from the surface of many animal cells. A central role attributed to these ciliated tissues is to effectively clear out toxic molecules and undesirable microbes; in work performed largely by Janna Nawroth (now at Emulate, Inc., Boston) and co-led by McFall-Ngai and Eva Kanso, a mathematical modeler at the University of Southern California, these ciliated tissues are shown to also selectively recruit beneficial microbes, called symbionts.

“A few years ago, when the biomedical community discovered that all of these surfaces of mammals have a rich co-evolved microbial consortium, a microbiome, that promotes the health of those systems, the question became: how do they do it—that is, by what mechanisms do they select the good microbes and reject the harmful ones?” explained McFall-Ngai.

Model system offers window into microscopic world

The ciliated tissues of most animals are inaccessible to observation and study. Using the Hawaiian bobtail squid and its single bacterial symbiont, Vibrio fischeri, as a model biological system, the collaborative research team—comprised of a biomechanicist/bioengineer, an applied physicist, mathematicians, an imager, a microbiologist and McFall-Ngai, a developmental biologist and biochemist—investigated the process by which an appropriate symbiont species is recruited into a host animal鈥檚 microbiome at the exclusion of all other bacteria. 

This model system provides a special window into such complex problems because the squid partners up with only one symbiont species, which it selects using the activity of a complex ciliated surface. In addition, the body plan of this animal is such that researchers can use microscopy to watch the process happen along this highly accessible tissue surface.

“We were surprised to find two different cilia behaviors,” said McFall-Ngai. “One behavior is typical of long cilia—very organized, with waves of cilia groups beating together. These fields of cilia serve to concentrate the bacterial partner into the areas where colonization will occur. We also found fields of short cilia that were beating, but each independently. The mathematical modeling and visualization showed that these shorter cilia serve to mix the chemical signals of the host cell so as to attract the partnering bacteria.”

From micro- to macro-scale

Because the structure and function of cilia are conserved throughout the evolution of animals, this study provides insight into the very basic function of ciliated surfaces.

“With this starting point, we can begin to determine how the whole system, host cells, their secretions and their bacterial partners, work to dissuade the colonization of these tissues by deadly pathogens, such as those that cause whooping cough, strep throat/ rheumatic fever, and two different types of pneumonia,” said McFall-Ngai. “This information may also aid development of ways to foster the acquisition and growth of beneficial bacterial partners along human respiratory, reproductive, and excretory tracts.”

For nearly three decades, McFall-Ngai and researcher at the 糖心Vlog官方 M膩noa School of Ocean and Earth Science and Technology’s Pacific Biosciences Research Center, have used the squid bacterial symbiosis system to characterize animal microbiomes. They discovered bacteria affecting animal development and bacterial partners driving circadian (daily) rhythms of their host.

• Related 糖心Vlog官方 News story and video: , February 5, 2017

These and other insights have contributed to expanding the once narrow view of the microbial world. Based on her distinguished and continuing achievements in original research, McFall-Ngai, was elected to the National Academy of Sciences in 2015. Election to the academy is one of the highest honors in the field of science.

The work was funded by the National Science Foundation INSPIRE (Integrated NSF Support Promoting Interdisciplinary Research and Education) grant to Eva Kanso; and National Institutes of Health grants to McFall-Ngai and Ruby.

—By Marcie Grabowski

The humble Hawaiian bobtail squid is helping to build the University of Hawaiʻi’s capacity in the hot field of microbiome research. A microbiome is a community of microorganisms. Researchers at 糖心Vlog官方 Mānoa’s are studying the simple squid and its interactions with a single bioluminescent bacterium (vibrio fisheri) that grows inside of it to shed light on the incredibly more complex human microbiome.

“We use the squid-vibrio system as a very simple model and the bacteria, this particular luminous bacterium that makes light for the squid associates with the animal cells in exactly the same way as our bacteria associate with our cells,” explains , director of the 糖心Vlog官方 Mānoa’s .

Pacific Biosciences Research Center Researcher adds, “And we hope that by understanding how it works in a simple model system like ours or like several others that are being studied out there, we’ll be able to understand how to maintain health of humans and how they maintain their beneficial associations.”

Microbiome research is so important that the White House announced a National Microbiome Initiative in 2016 to understand, protect and restore healthy microbiome function, with specific implications for human health, environmental sustainability and energy and food production.

• Related 糖心Vlog官方 News story: , May 26, 2016

“Not only is the diversity of the biosphere principally microbial, but the health of every single corner of the biosphere relies on the interactions that corner of the biosphere has with the microbial world,” says McFall-Ngai. “It’s huge and deep.”

With more than a dozen researchers, led by three members of the , including McFall-Ngai, 糖心Vlog官方 is a veritable microbiome powerhouse. McFall-Ngai says with the isolation and landscape of the Hawaiian Islands, the university is also uniquely positioned to study the interactions between environmental microbial communities and the human microbiome, and refers to it as “total virgin frontier.”

As she sees it, with expertise across multiple disciplines, the University of Hawaiʻi is poised at the vanguard of environmental microbiome research.

—By Kelli Trifonovitch

The small but charismatic Hawaiian bobtail squid is known for its predator-fooling light organ. To survive, the nocturnal cephalopod depends on a mutually beneficial relationship with the luminescent bacterium, Vibrio fischeri, which gives it the ability to mimic moonlight on the surface of the ocean, and deceive monk seals and other predators that would happily make a meal of the small creature.

by , professor at the University of Hawaiʻi at Mānoa’s and colleagues from the revealed that Vibrio fischeri has a novel type of receptors that sense the presence and concentration of fatty acids, a building block of all cell membranes. This class of receptors allows a bacterium to migrate toward short-chain fatty acids—a phenomenon referred to as chemotaxis.

“This is the first example of a receptor for this class of compounds, and this receptor appears to have evolved in, and be restricted to, the Vibrionaceae family of marine bacteria,” said Ruby.

The language of bacteria

Sending and receiving chemical signals allow bacteria to communicate with other organisms, gather information about their environment and determine with whom to create a mutually beneficial partnership— a symbiosis. For example, the Hawaiian bobtail squid hatchlings aren’t born with Vibrio fischeri. They attract it, and only it, from the surrounding seawater using chemoattractants, and capture it in their light organs.

Mysterious function

However, the newly discovered fatty-acid sensors are not required for the bacterium to initiate symbiosis with the squid. Thus, the ability to migrate towards fatty acids appears to play a critical role in some other aspect of the bacterium’s life history.

“Interestingly, in Vibrio fischeri the gene encoding the receptor has duplicated, so that the cell has two copies of similar, and apparently functionally identical, genes. Such genetic investment in this receptor suggests that the ability to sense and migrate toward fatty acids may be important in the pathogenicity of other Vibrio species like Vibrio cholera [which causes cholera], Vibrio vulnificus [which causes necrotizing skin infections and gastroenteritis] and others,” said Ruby.

A chemical attraction

All organisms, even humans, use chemotaxis to attract beneficial microbes to specific tissues. For example, as human infants are exposed to bacteria in their environment, they must attract desirable species to particular tissues—gut, skin, teeth, reproductive tract—that must be colonized by these bacteria.

In the future, Ruby and colleagues will continue to try and discover the attractants that allow Vibrio fischeri to be the only bacterial species that can colonize the light organ of the squid. With only one species to track, it is easier to study the colonization process than when there are dozens or hundreds of bacterial species that are needed to colonize the tissue (like the gut).

Understanding how this colonization takes place will lead to greater understanding of how Earth’s many microbiomes become constructed and, thus allow us to better construct and manage them.

—By Marcie Grabowski