Most bottom-dwelling marine invertebrate animals, such as sponges, coral, worms and oysters, produce small larvae that float in the ocean before attaching to the ocean floor and turning into juveniles. A new study published in Proceedings of the National Academy of Science (PNAS) and the University of Hawaii (UH) at Manoa revealed that a large, complex molecule produced by bacteria, called a lipopolysaccharide, is responsible for inducing the larval marine tubeworm, hydrides elegans, To settle on the ocean floor and begin the complex processes of metamorphosis.
Michael Hadfield, senior author of the paper and emeritus professor in the UH Manoa School of Ocean and Earth Science and Technology, said, “This is a major milestone in understanding the factors that determine where the larvae of invertebrates live below.” settle and metamorphose.” “This is key to understanding how benthic communities are established and maintained on all surfaces, under salt water, that is, on 71% of Earth’s surface.”
Most invertebrate larvae are able to remain in the larval stage for a long time until they find a suitable location. In the study, led by Marnie Frekelton, a postdoctoral researcher at the Kevalo Marine Lab, a unit of the Pacific Biosciences Research Center (PBRC) at SOEST, the research team asked the question: how do the ‘right spots’ make the larvae settle and Transform?
Metamorphosis is a profound change in animal form – from a small swimming larva to an animal with a very different anatomy that is attached to the ocean floor. Although researchers have known that biofilms, thin layers consisting of bacteria, diatoms and small algae that blanket submerged surfaces, induce the metamorphosis of a wide range of marine invertebrate larvae, the mechanism of induction remains poorly understood.
In laboratory experiments with larval tubeworms, the team found that they would not settle on clean surfaces. They needed a cue from a surface biofilm.
“The team isolated a single bacterial species, Cellulophaga lytica, Which, when formed in a surface biofilm, can induce worm larvae to settle, and then we asked: What is it about that particular bacterium that causes the larvae to settle down and metamorphose?” Freckelton said.
With a series of enzyme experiments, the researchers eliminated protein-based bacterial compounds as potential disposal indicators. From there, they examined the various lipid-containing compounds, one by one, and identified the trigger — the lipopolysaccharide, which makes up the outer coat of most marine bacteria.
They studied biofilm-bacterial communities from many different habitats to find out what bacterial species were present and how they compared the communities. They found that, although thousands of bacterial species form biofilms in any given marine habitat, they differ significantly from one location to another.
“In fact, we have different strains of the same bacterial species obtained from Kenohe Bay and Pearl Harbor, and hydrides larvae settle In college In response to the Pearl Harbor one,” said Hadfield, who has been a researcher at the Kewalo Marine Lab at PBRC since 1968. “In addition, we found in our lab that coral larvae Posilopora Demicornis, which is abundant in Keneohe Bay, will only settle in response to the Keneohe Bay strain of the bacterium. This is a breakthrough, because it tells us about the specificity of certain bacteria that guide and maintain the animal community where they occur.”
Recent discoveries may aid in many urgent problems, such as coral-reef restoration; Marine farming of clams, oysters, mussels and possibly shrimp and crabs; and bio-contamination, the accumulation of animals and algae on ship hulls, costing the world’s navies and shipping industry billions of dollars per year.
“Hopefully, we can aid in these efforts by discovering bacterial molecules — potential lipopolysaccharides — that guide the disposal of lab-reared coral in vulnerable reef areas or oyster larvae in places like Pearl Harbor to clean water.” to employ our filtering capabilities, as has already been done in the Chesapeake Bay,” Hadfield said. “Further, our research may contribute directly to the development of ship hull coatings that resist biofouling.”
material provided by University of Hawaii at Manoa, Original written by Marcy Grabowski. Note: Content can be edited for style and length.