Media contact: dkenney@mbl.edu

WOODS HOLE, Mass. -- Stationary marine organisms that don’t ply the ocean, but spend their lives rooted in one spot, have evolved impressive ways to capture prey. The sea anemone Nematostella, for instance, burrows into salt marsh sediments and stays there for life. And it has specialized ‘stinging cells’ that hurl toxins into passing prey, immobilizing the morsel 'til the anemone can snatch it with its tentacles.

New research from the Marine Biological Laboratory (MBL), however, finds that Nematostella’s growth, development, and feeding ability are drastically impacted by present levels of common pollutants - including plasticizers - found in one of its native habitats, the U.S. East Coast.

Native to the U.S. East Coast, Nematostella vectensis is an important research organism for fundamental studies in developmental, regenerative, and evolutionary biology. This is the first study to look at the impact of marsh pollutants on Nematostella’s growth, development, and microbiome. Credit: Marine Biological Laboratory/BioQuest Studios

“The numbers of Nematostella in the wild have been dramatically decreasing over time,” said senior author Karen Echeverri, associate scientist in the MBL’s Bell Center for Regenerative Biology and Tissue Engineering. This study pinpoints factors that threaten the species, which is already under protection in the United Kingdom.

The MBL team focused on phthalates (plasticizers), chemicals that are widely used in plastic packaging and other consumer products that wash into the ocean; and potassium nitrate, which enters marshes through runoff from lawn fertilizers.

When Nematostella embryos were exposed to phthalate and nitrate concentrations commonly found in coastal environments (1-20 µM), they showed a gross decrease in body size two weeks after exposure. The animals also had fewer tentacles, and the tentacles that did grow were misshapen or uneven in length or number. In addition, the pollutant-exposed animals had a severely reduced number of stinging cells (cnidocytes), which they use as a defense mechanism and to capture food.

Nematostella has specialized stinging cells on its skin and tentacles that it uses for self-defense and predation. After exposure to common marsh pollutants, Nematostella embryos exhibit severe developmental defects, including decreased body size, missing or misshapen tentacles, and reduced numbers of stinging cells. Credit: Marine Biological Laboratory/BioQuest Studios

“At a certain point, the animals just die, because they can’t defend themselves or feed themselves properly,” said Echeverri.

Because Nematostella is sessile (stationary), it must constantly acclimate to environmental changes, such as temperature and salinity. “They have what we call adaptive plasticity; they are resilient to change,” Echeverri said. “But we think there is a limit to that resilience. And as you bring in more pollution, they reach that limit of resilience much faster.”

The study is unusual in that it integrates assessment of the pollutants’ impact on Nematostella’s microbiome. Led by MBL scientists Mitchell Sogin and Emil Ruff, the team sequenced the microbiomes of animals after 10 days of pollutant exposure.

“Certain classes of microbes became much more dominant after exposure,” said Echeverri. “How this affects the physiology of the animal, we don’t completely know yet.”

Nemostella adults in Karen Echeverri’s lab at the Marine Biological Laboratory. Credit: Karen Echeverri

Shifts in the microbiome can serve as sentinels of change in the health of the host, as shown by prior studies in other animals, including corals and humans.

“A next step is to link changes in the Nematostella microbiome to changes in the animal’s development,” Echeverri said.

Other studies of the effects of phthalates on embryonic development in vertebrates, including frogs and zebrafish, identified defects in body growth similar to what was found in Nematostella. These include slower body growth and defects of cells in the ectodermal lineage (such as the cnidocytes). Impacts on the endocrine system and on fertility have also been documented in other species.

Citation:

Sylvia Klein, Victoria Frazier, Timothy Readdean, Emily Lucas, Erica P. Diaz-Jimenez, Mitchell Sogin, Emil S. Ruff and Karen Echeverri (2021) Common Environmental Pollutants Negatively Affect Development and Regeneration in the Sea Anemone Nematostella vectensis Holobiont. Front. Ecol. Evol. DOI: 10.3389/fevo.2021.786037

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The Marine Biological Laboratory (MBL) is dedicated to scientific discovery – exploring fundamental biology, understanding marine biodiversity and the environment, and informing the human condition through research and education. Founded in Woods Hole, Massachusetts in 1888, the MBL is a private, nonprofit institution and an affiliate of the University of Chicago.

University of Chicago neurobiologists William Green (left) and Okunola Jeyifous in the university’s Light Microcopy Imaging Core, Biological Sciences Division. Photo courtesy of W. Green.

The neural pathways in our brains aren’t set in stone: They physically change when we store knowledge or memories, or with addiction or neural disease. A recent study helps illuminate the changes that nerve cells undergo as neural circuits form and are reshaped by experience.

The study was conducted partly at the Marine Biological Laboratory (MBL), where co-authors William (Bill) Green, professor of Neurobiology at University of Chicago, interacted with Jennifer Lippincott-Schwartz, senior group leader at HHMI’s Janelia Research Campus. Lead author Okunola Jeyifous, research assistant professor at UChicago, also conducted some of the research at MBL.

The team discovered that excitation of neurons leads to remarkable changes in the secretory pathway where certain proteins, called glycoproteins, are processed for export to the neuron’s surface. In particular, an important organelle in the secretory pathway, the Golgi apparatus, dissolves from being a unified structure into scattered elements, called Golgi satellites.

The Golgi satellites arise in the neuron’s dendrites – the long, thin nerve processes that receive signals from adjacent neurons. The satellites function as local micro-secretory systems, processing glycoproteins at a good distance from the neuron's cell body, where the Golgi apparatus resides.

The study grew out of longstanding work in Green’s lab on nicotine addiction. Using cultured neurons from the rat brain, they found that nicotine exposure triggered Golgi dispersal within the cell body and dendrites, and subsequently showed that exposure to other excitatory stimuli did as well.

“This finding helps us understand how addiction hijacks the secretory system and then changes the circuitry in the brain,” Green says. “But it also tells as something really important about the basic workings of the brain -- how neural circuits form.”

Green spends most summers conducting research in the MBL Whitman Center. Lippincott-Schwartz, an expert in the Golgi apparatus as well as microscopy, is a faculty member and former co-director of the MBL Physiology course.

The team acknowledges microscopy support for this study from Louis Kerr, director of Imaging Services and staff scientist at MBL; Abhishek Kumar, CZI imaging scientist at MBL; and Hari Shroff, MBL fellow from the National Institute of Biomedical Imaging and Bioengineering.

Cultured rat CNS neurons treated with nicotine (right panel) vs. untreated neurons (left panel) expressing fluorescently tagged sialyltransferase3 (St3), a marker for Golgi satellites and the Golgi apparatus. The larger structure in the cell body (soma) is the Golgi apparatus and the smaller puncta are Golgi satellites. Nicotine exposure increases Golgi satellite number throughout the soma and neuronal processes only for neurons expressing the α4β2-type of nicotinic receptors. In the absence of nicotinic receptors, increases in synaptic activity result in similar increases in Golgi satellite number (see Govind et al., 2021). Credit: Okunola Jeyifous

Citation:

Anitha P. Govind et al (2021) Activity-dependent Golgi satellite formation in dendrites reshapes the neuronal surface glycoproteome. eLife, DOI: 10.7554/eLife.68910.sa2

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The Marine Biological Laboratory (MBL) is dedicated to scientific discovery – exploring fundamental biology, understanding marine biodiversity and the environment, and informing the human condition through research and education. Founded in Woods Hole, Massachusetts in 1888, the MBL is a private, nonprofit institution and an affiliate of the University of Chicago.

By Stephanie M. McPherson

MBL Hibbitt Fellow B. Duygu Özpolat. Credit: Daniel Cojanu

Duygu Özpolat at the Marine Biological Laboratory (MBL) is tracing the lineage of regenerated reproductive cells—also called the germline—to determine the cellular programming that allows for their resurgence.

“We are trying to understand where the cells that regenerate the germline come from,” says Özpolat. “Once we know that, we may be able to understand why some organisms can regenerate them and some can’t.” Özpolat is a Hibbitt Fellow in the MBL’s Bell Center for Regenerative Biology and Tissue Engineering.

Now, Özpolat and her colleagues are a step closer to this goal. A recent study reveals that their research organism, the marine worm Platynereis dumerilii, must develop a certain number of body segments before it starts forming its original reproductive cells.

“If you're going to study the regeneration of a structure in an organism, you need to know how that original structure formed first,” says Özpolat. “And before this study, we didn't have a good understanding of when that happens.”

The paper, published in the Journal of Experimental Zoology Part B: Molecular and Development Evolution, shows that progenitor reproductive cells develop in P. dumerilii when the worms reach between 35 and 40 segments. Before this discovery, researchers working with P. dumerilii would have to conduct time-consuming assays to determine if the worm had enough original reproductive cells to begin experimentation.

Led by Özpolat and first author Emily Kuehn, a research assistant in Özpolat’s lab, the researchers used a technique called in situ hybridization to locate the germline cells in the worm’s body and track their development as segments were added. They studied hundreds of the two-centimeter worms, carried out different interventions, and generated a wealth of data that led them to their remarkably consistent conclusion.
 

The Özpolat lab’s research organism, Platynereis dumerilii. Credit Ryan Null

The team also published a first-of-kind algorithm to facilitate the use of a fluorescent in situ hybridization method in this type of experiment.

This research builds on years of work from the Özpolat lab. For example, the worms were cultured using a streamlined, scalable system developed in the lab and published in 2019. A standardized culturing system is key to understanding genetic cause and effect. If worms grow in different environments with different feeding schedules, it is nearly impossible to determine if variations observed in experiments are due to the scientists’ interventions or to growth conditions.

Özpolat and team will follow this research with investigations into what happens when germline cells are forced to regenerate. They will amputate 90 percent of the worms’ length and watch as the germlines reemerge. They will then track the function of those regenerated cells and their effect on the health of the next generation, versus control worms who reproduce without being forced to regenerate germline cells.
 

Fixed sample of the marine worm (P. dumerilii) processed for in situ hybridization to detect vasa gene expression. She is filled with oocytes, and she no longer has any internal organs. This is a part of the sexual metamorphosis process, when the worms lose their internal organs, and become mere carriers of gametes. Credit: Kuehn et al JEZ-B 2021

Understanding the cellular and molecular pathways involved in regeneration could help Özpolat and her team understand how to make it happen in humans.

“Way down the line, this could inform infertility treatments,” says Özpolat. “Our job in fundamental science is to learn how these worms do cellular reprogramming. And if they keep the mutations at the low level, how they do that? Then maybe we can apply that to human therapies for regenerating cells or reprogramming cell types from different body parts.”

Citation:

Emily Kuehn, David S. Clausen, Ryan W. Null, Bria M. Metzger, Amy D. Willis, B. Duygu Özpolat (2021) Segment number threshold determines juvenile onset of germline cluster expansion in Platynereis dumerilii. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution, DOI: 10.1002/jez.b.23100

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The Marine Biological Laboratory (MBL) is dedicated to scientific discovery – exploring fundamental biology, understanding marine biodiversity and the environment, and informing the human condition through research and education. Founded in Woods Hole, Massachusetts in 1888, the MBL is a private, nonprofit institution and an affiliate of the University of Chicago.

WOODS HOLE, Mass. — For generations, scientists have relied on a handful of organisms to study the fundamentals of biology. The usual suspects—fruit flies, zebrafish, and mice, among others—all have short lifespans, small body size, can be bred through multiple generations in the laboratory, and have been developed for genetic investigations. These research organisms leave out a whole swath of biological diversity and scientists have lacked access to a cultured octopus laboratory organism—until now. Introducing the pygmy zebra octopus (O. chierchiae).

In a new paper published in the journal Frontiers in Marine Science, researchers from the Marine Biological Laboratory (MBL) introduce scientists to successful culturing methods for O. chierchiae that were developed at the MBL.

O. chierchiae adult in a shell looking at a snail. Credit: Tim Briggs

“The pygmy zebra octopus has certain biological features that make them attractive and more appropriate for laboratory research, compared to other octopuses,” says Bret Grasse, MBL’s manager of Cephalopod Operations and co-author on the paper.

Also known as the “lesser Pacific striped octopus,” the pygmy zebra octopus shares many useful similarities with other research organisms—such as small adult body size—but it also has unique features that distinguish it from other cephalopods (the group of animals that include octopus, squid, and cuttlefish).

“The majority of octopuses are ‘live fast, die young.’ They breed once and then immediately start to senesce and age and then die relatively quickly,” says Anik Grearson, former MBL intern and co-lead author on the paper. Unlike other octopus species, a female O. chierchiae lays several clutches of 30-90 eggs over her reproductive period.

“We can mate them and know exactly when they’ll lay their eggs. We know exactly how long they’ll incubate and we can raise offspring at a relatively high survivorship rate compared to other octopuses,” says Grasse. Add that to its small size, sexual dimorphism, and predictable breeding schedule and it’s easy to see why O. chierchiae is an ideal candidate for further exploration and research.

A pygmy zebra octopus hatchling in the MBL Cephalopod Mariculture Lab. These octopuses are about the size of a grain of rice when they hatch. They reach full size (about the size of a table grape) within six months. Credit: Tim Briggs.

Anik Grearson, co-lead author on the paper, leans over a tank in the MBL Cephalopod Mariculture Lab. She was an intern at the MBL during 2019 while she was getting her bachelor’s degree from McMaster University. She is currently in a master’s degree program at Northeastern University.

The MBL’s Cephalopod Mariculture team successfully bred O. chierchiae through multiple generations in 2019 — a global first. Breeding multiple generations in the lab is known as “closing the life cycle” and it is critical in biological research. It lets scientists study gene function and mutational effects from one generation to the next.

Being able to successfully breed octopuses in a laboratory opens up “novel science that hasn’t been possible before,” says Grasse.

Scientists at the MBL and around the world study cephalopods to learn about everything from camouflage and limb dexterity to regeneration and neurobiology. The majority of U.S. scientists studying octopuses use the California two-spot octopus (O. bimaculoides), which is local to the waters off of California. But those octopuses have yet to be successfully bred in the laboratory through multiple generations, so most scientists study wild-caught animals shipped to their labs from California.

Octopuses are also territorial, and each organism must be housed individually. An adult two-spot octopus is about the size of a softball, whereas an adult pygmy zebra octopus is only the size of a table grape, making the smaller-size species ideal for space-conscious laboratories.

“We now have this octopus species that’s really small and that can be bred regularly,” says Grearson. “The sky’s the limit for what people want to do.”

Reference:

Grearson A.G., Dugan A., Sakmar T., Sivitilli D.M., Gire D.H., Caldwell R.L., Niell C.M., Dölen G., Wang Z.Y. and Grasse B. (2021) The Lesser Pacific Striped Octopus, Octopus chierchiae: An Emerging Laboratory Model. Frontiers in Marine Science. Doi: 10.3389/fmars.2021.753483

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The Marine Biological Laboratory (MBL) is dedicated to scientific discovery – exploring fundamental biology, understanding marine biodiversity and the environment, and informing the human condition through research and education. Founded in Woods Hole, Massachusetts in 1888, the MBL is a private, nonprofit institution and an affiliate of the University of Chicago.

By Bill O’Neill

We know that sharks are voracious eaters, but what do we know about the source of its microbiome? To date, not much. But a recent study from the University of Chicago and the Marine Biological Laboratory (MBL) fills a gap in understanding the microbiome associated with a close relative in the Chondrichthyes, a class of fish that includes sharks, rays and skates.

Postdoctoral Scholar Katelyn Mika and Alexander Okamoto, then an undergraduate at UChicago, were inspired to discover how the microbiome originates in the little skate in 2018, while spending the summer at MBL with UChicago Professor Neil Shubin. Also guiding them in the research was MBL Senior Scientist David Mark Welch.

“There’s a new understanding that microbiomes are very important for all multicellular organisms,” said Mark Welch, senior author on the paper. “We're essentially taking what we’ve learned from the NIH Human Microbiome Project, including the central role the microbiome plays in human health, and recognizing that microbiomes play a role in a wide variety of organisms, particularly marine organisms.”

Alexander Okamoto holds a skate egg case (Leucoraja erinacea) in the MBL Marine Resources Center. Credit: Marine Biological Laboratory

Among the ocean dwellers, corals and certain fish have had their microbiomes analyzed, but “there are huge gaps [in knowledge], and one of them has been the microbiomes of non-bony fish – sharks, rays, skates and other cartilaginous fish,” Mark Welch said.

An animal can acquire its microbiome in three different ways, the team’s study explains. First, the parent can transmit all or part of its microbiome to its offspring. Second, the animal can acquire it during social or sexual interactions with other members of its species. And third, animals can recruit microbes from their environment through contact with fluids, habitat, or diet. Humans acquire their microbiome in all three ways.

The little skate’s embryo develops in the contained environment of an egg case, commonly called a devil’s purse.

“The skate egg case is a very interesting place to study microbiome development because the egg is separate from the outside world up until a certain stage of development, when little apertures open in the egg case and there starts to be an exchange with seawater,” said Mark Welch. “So, you can ask the question more easily than in other organisms, is there vertical transmission of the microbiome? Namely, does the mother pass on part of her microbiome to the offspring?”

An adult little skate (Leucoraja erinacea) in the MBL Marine Resources Center. Credit: Andres Pruna

A little skate embryo in its case, commonly called a devil’s purse. Credit: Laurel Hamers

Mika and Okamoto got on the trail of this question when they heard a talk by Andrew Gillis, who is joining the MBL next year as an associate scientist. Gillis’s description of the skate egg case opening to the environment about two-thirds of the way through development caught their attention.

“We began wondering what happens with the microbiome, given the egg’s fairly dramatic life history changes,” said Okamoto.  “It’s basically dumped on the bottom of the ocean, abandoned by its parent for many months, and then it opens up suddenly and seawater rushes in.”

“Alexander and I looked at each other and said, ‘That's weird,’ because most eggs are fully sealed until the time of hatching, and these are not,” said Mika.

They conducted the research during the summer of 2019, while Okamoto was working as a research assistant in MBL Director Nipam Patel’s lab. Using next-generation sequencing to characterize the microbial community at six points in the skate’s embryonic development, their efforts yielded the first evidence of vertical transmission of the microbiome from parent to offspring in the Chondrichthyes.

Katelyn Mika and Alexander Okamoto by the Rachel Carson statue in MBL’s Waterfront Park. Credit: Alexander Okamoto

“This was the first microbiome study Alexander and I had ever done,” said Mika. “I'm a geneticist and he's worked on evolutionary and organismal biology, so we were both a bit out of our depth. We had to learn as we went.”

Their findings are a useful step in the study of microbiomes, which can be indicators of how well an organism is doing in its environment, said Mark Welch.

“We know that a lot of marine species are under stress because of anthropogenic changes, global warming,” he said. “One of our broader goals is to be able to study the microbiomes of these organisms and determine very quickly, how healthy are they?”

There’s plenty of room for more research on animal microbiomes, said Mika – including on sharks.

“There's a chain catshark at the MBL whose eggs look incredibly similar to the skates' eggs,” she said. “They go through the same sort of development where they're in that egg case for the first two thirds, then they have slits that open, and then they finish developing with that open waterflow through the eggs. I'm desperate to know if their microbiomes are similar to the skates' or if they're totally different.” Sounds like a good reason to come back to the MBL!

This research was funded by a grant from the Microbiome Center, a collaboration between University of Chicago, Marine Biological Laboratory, and Argonne National Laboratory; and by a National Science Foundation Graduate Research Fellowship to Alexander Okamoto.

Citation:

Katelyn Mika, Alexander Okamoto, Neil Shubin and David Mark Welch (2021) Bacterial community dynamics during embryonic development of the little skate (Leucoraja erinacea). Animal Microbiome, DOI: 10.1186/s42523-021-00136-x

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The Marine Biological Laboratory (MBL) is dedicated to scientific discovery – exploring fundamental biology, understanding marine biodiversity and the environment, and informing the human condition through research and education. Founded in Woods Hole, Massachusetts in 1888, the MBL is a private, nonprofit institution and an affiliate of the University of Chicago.