Marine Biological Laboratory — Biological Discovery in Woods Hole

Squid Studies Illuminate Neural Dysfunction in ALS; Suggest New Route to Therapy

Contact: dkenney@mbl.edu; 508-685-3525

WOODS HOLE, Mass. -- Amyotrophic lateral sclerosis (ALS) is one of the most devastating adult-onset neurodegenerative diseases. Patients, including the late actor/playwright Sam Shepard, become progressively weaker and eventually paralyzed as their motor neurons degenerate and die.

Yuyu Song at the Marine Biological Laboratory.

To find a cure for ALS, which is fatal, scientists need a deeper understanding of how it interrupts motor neuron communication channels. Because motor neurons reach from the brain to the spinal cord, and from the spinal cord to the muscles, when they die, the brain can no longer initiate muscle movement.

Yuyu Song of Harvard Medical School was a Grass Fellow at the Marine Biological Laboratory (MBL) when she took advantage of a powerful research organism in neuroscience, the local squid, to start asking how a mutant protein associated with familial ALS behaves under controlled conditions.

Her study, recently published in eNeuro, clarifies the mechanisms underlying neural dysfunction in ALS, and also suggests a novel approach to restoring the health of motor neurons in patients with the disease.

Restoring neurotransmission

Song focused on how this mutant protein, called G85R-SOD1, affects neurotransmission at the squid “giant synapse,” the junction where neurons transmit chemical signals to muscle fibers, causing the muscle to contract. The squid giant synapse is one of the few mature nervous systems that mimics human neuromuscular junctions, while allowing precise experimental manipulations and live measurements.

Song showed that the presence of misfolded mutant SOD1 inhibits synaptic transmission and diminishes the pool of synaptic vesicles, whose job is to deliver neurotransmitters critical for neuronal connections.

Surprisingly, synaptic function was restored by intermittent, high-frequency stimulation, which suggested aberrant calcium signaling may underlie SOD1 toxicity to normal synaptic transmission. To test this hypothesis, Song used calcium imaging to capture the abnormal calcium influx in the presynaptic terminal and confirmed the protective role of a calcium chelator, which corrected the calcium imbalance without affecting neurotransmission.

This suggests a new approach to therapeutic intervention for ALS, in which chemical or electrical regulation of calcium and its downstream signaling pathways may restore the health of motor neurons.

A catch of the Woods Hole squid, Doryteuthis pealeii, aboard the MBL collecting boat, The Gemma. Credit: Daniel Cojanu

“Altogether, our results not only demonstrated synaptic dysfunction related to ALS and its underlying molecular pathways, but also extended our understanding of fundamental synaptic physiology,” Song says.

Developing a novel disease model - and finding a family

Song, who is an MD-PhD, has spent numerous summers at the MBL using the local squid to unravel the basic pathologies underlying neurodegenerative disease. She started coming regularly in 2007 as a graduate student with Scott Brady, whose lab was developing the squid’s giant axon (nerve fiber) as a system for studying human disease.

“One summer, I chatted with Rodolfo Linas at the MBL, who has been doing synaptic recordings in the squid for many decades,” Song says. “I helped his lab with some electron microscopy on the squid giant synapse together with Jorge Moreira, and Rodolfo challenged/encouraged me to do synaptic studies myself. In the summer of 2013, I decided to establish the squid giant synapse as a disease model for ALS and to learn electrophysiology in this classical preparation.”

That same summer, Song met Whitman Center scientists Steve Zottoli, George Augustine and Len Kaczmarek, who advised her to apply for a Grass Fellowship, in which she could set up an independent research project at MBL. After her productive Grass Lab experience, Song returned to the MBL for several years as a Whitman Center scientist and initiated further collaborations with MBL and University of Chicago scientists.

Song found an enduring family at the MBL, she says. “The 2014 Grass Fellows are still in touch with one another and we share our success and struggle in life and science together,” she says. The Grass Lab’s directors and administrators remain dear friends. And she is quick to acknowledge the essential contribution of the MBL’s collecting operation, which provides a daily catch of squid to her and other MBL scientists in season. “All the crew in the Marine Resources Center feel like family, not just scientific collaborators,” she says.

Currently, Song is an instructor in neurology at Harvard Medical School and Massachusetts General Hospital. And she is waiting – like so many researchers –for the green light to return to Woods Hole!

Citation:

Song, Yuyu (2020) Synaptic Actions of Amyotrophic Lateral Sclerosis-Associated G85R-SOD1 in the Squid Giant Synapse. eNeuro, DOI: 10.1523/ENEURO.0369-19.2020

Homepage image: The longfin inshore squid (Doryteuthis pealeii). Credit: Roger Hanlon

—###—

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.

Little Skates Could Hold the Key to Cartilage Therapy in Humans

Contact: dkenney@mbl.edu; 508-685-3525

By Emily Greenhalgh

A little skate (Leucoraja erinacea) hatchling (left) with a skeletal preparation of a little skate hatchling (right), with cartilage stained blue and mineralized tissues stained pink. Credit: Andrew Gillis

WOODS HOLE, MASS. — Nearly a quarter of Americans suffer from arthritis, most commonly due to the wear and tear of the cartilage that protects the joints. As we age, or get injured, we have no way to grow new cartilage. Unlike humans and other mammals, the skeletons of sharks, skates, and rays are made entirely of cartilage and they continue to grow that cartilage throughout adulthood.

And new research published this week in eLife finds that adult skates go one step further than cartilage growth: They can also spontaneously repair injured cartilage. This is the first known example of adult cartilage repair in a research organism. The team also found that newly healed skate cartilage did not form scar tissue.

“Skates and humans use a lot of the same genes to make cartilage. Conceivably, if skates are able to make cartilage as adults, we should be able to also,” says Andrew Gillis, senior author on the study and a Marine Biological Laboratory Whitman Center Scientist from the University of Cambridge, U.K.

The researchers carried out a series of experiments on little skates (Leucoraja erinacea) and found that adult skates have a specialized type of progenitor cell to create new cartilage. They were able to label these cells, trace their descendants, and show that they give rise to new cartilage in an adult skeleton.

Why is this important? There are few therapies for repairing cartilage in humans and those that exist have severe limitations. As humans develop, almost all of our cartilage eventually turns into bone. The stem cell therapies used in cartilage repair face the same issue—the cells often continue to differentiate until they become bone. They do not stop as cartilage. But in skates, the stem cells do not create cartilage as a steppingstone; it is the end result.

“We’re looking at the genetics of how they make cartilage, not as an intermediate point on the way to bone, but as a final product,” says Gillis.

The research is in its early stages, but Gillis and his team hope that by understanding what genes are active in adult skates during cartilage repair, they could better understand how to stop human stem-cell therapies from differentiating to bone.

Note: There is no scientific evidence that “shark cartilage tablets” currently marketed as supplements confer any health benefits, including relief of joint pain.

Citation: Aleksandra Marconi, Amy Hancock-Ronemus and J. Andrew Gillis (2020) Adult chondrogenesis and spontaneous cartilage repair in the skate, Leucoraja erinacea. eLife, DOI: https://doi.org/10.7554/eLife.53414

—###—

Window to Another World: Life is Bubbling Up to Seafloor with Petroleum from Deep Below

Contact: dkenney@mbl.edu; 508-685-3525

Recovering sediment cores from the Gulf of Mexico on the TDI-Brooks vessel R/V Brooks McCall. Credit: Daniel Brooks

WOODS HOLE, Mass. —The COVID-19 pandemic is a stark reminder that we move through a world shaped by unseen life. Bacteria, viruses, and other microscopic organisms regulate the Earth’s vital functions and resources, from the air we breathe to all our food and most of our energy sources. An estimated one-third of the Earth’s microbes are literally hidden, buried in sediments deep below the ocean floor. Now, scientists have shown that these “deep biosphere” microbes aren’t staying put but are bubbling up to the ocean floor along with fluids from buried petroleum reservoirs. These hitchhikers in petroleum seeps are diversifying the microbial community that thrives at the seafloor, impacting deep-sea processes, such as carbon cycling, that have global implications.

“This study confirms that petroleum seeps are a conduit for transporting life from the deep biosphere to the seafloor,” says co-author Emil Ruff, a scientist at the Marine Biological Laboratory (MBL), Woods Hole. The study, led by Anirban Chakraborty and Casey Hubert of the University of Calgary, is published this week in Proceedings of the National Academy of Sciences.

The team analyzed 172 seafloor sediment samples from the eastern Gulf of Mexico that had been collected as part of a 2011 survey for the oil industry. A fraction of these samples contained migrated gaseous hydrocarbons, the chief components of oil and gas. These petroleum seeps on the ocean floor harbored distinct microbial communities featuring bacteria and archaea that are well-known inhabitants of deep biosphere sediments.

“Whereas sedimentation slowly buries microbial communities into the deep biosphere, these results show that it’s more of a two-way street. The microbes coming back up offer a window to life buried deeper below,” Hubert says. “These relatively accessible surface sediments give us a glimpse into the vast, subsurface realm.”

The study also adds a new dimension to understanding the metabolic diversity of seabed petroleum seep microbial communities. “If it weren’t for the microbes living at hydrocarbon seeps, the oceans would be full of gas and oil,” Chakraborty says.

Co-authors Bernie Bernard and James Brooks of TDI-Brooks International obtained the 172 Gulf of Mexico sediment cores and performed geochemical testing on them, setting the stage for microbiology testing at the University of Calgary.

“One of the strengths of this study is the large number of samples analyzed, allowing robust statistical inferences of the microbes present in the petroleum seeps,” Ruff says. Because the seafloor is so difficult to access, explorations of deep-sea ecosystems are often limited by the number and quality of samples. The team used metagenomic approaches to determine what microbes were present in the sediment samples, and genome sequencing of particularly interesting organisms to indicate what their activity in the subsurface might be.

Citation: Anirban Chakraborty et al (2020) Hydrocarbon seepage in the deep seabed links subsurface and seafloor biospheres. Proc. Natl. Acad. Sci., DOI: 10.1073/pnas.2002289117

Homepage photo:

Hydrocarbon seep in the southern Gulf of Mexico emitting a viscous petroleum, much like asphalt. Hydrocarbons serve as an energy source for microbes and in turn, microbial biomass is a food source for a diverse community of organisms including tube worms, mussels, crabs and shrimp. Credit: Center for Marine Environmental Sciences (MARUM), University of Bremen

—###—

The Evolution of Color: Team Shows How Butterfly Wings Can Shift in Hue

Contact: Diana Kenney
dkenney@mbl.edu; 508-685-3525

WOODS HOLE, Mass. – A selective mating experiment by a curious butterfly breeder has led scientists to a deeper understanding of how butterfly wing color is created and evolves. The study, led by scientists at University of California, Berkeley, and the Marine Biological Laboratory, Woods Hole, is published today in eLife.

When the biologists happened upon the breeder’s buckeye butterflies–which normally are brown–sporting brilliant blue wings through selective mating, they jumped on the chance to explore what caused the change in color of the tiny, overlapping scales that produce the wing’s color pattern. They found that buckeyes and other Junonia species can create a rainbow of structural colors simply by tuning the thickness of the wing scale’s bottom layer (the lamina), which creates iridescent colors in the same way a soap bubble does.

Buckeye butterfly (Junonia coenia) with typical brown wing coloration. Credit: Nipam Patel

Buckeye butterfly (Junonia coenia) selectively bred to shift wing color from brown to blue. Credit: Edith Smith

Structural color, often used in butterflies and other animals to create blue and green, is created by microscopic structures interacting with light to intensify some colors and diminish others. In contrast, pigmentary coloration is created by the absorption of specific colors (wavelengths) of light and is commonly employed to create colors such as yellow, orange, and brown.

“It was a surprise to find that the lamina, a thin sheet that looks very simple and plain, is the most important source of structural color in so many butterfly wing scales,” says first author Rachel Thayer. Previous studies of structural coloration had largely focused on some extreme examples and mostly involved analyzing complex, 3D shapes on the top of the scales.

Magnified view of the wings of two buckeye butterflies. At top, just a few scattered blue scales are within the wing’s eyespot. Below, there is a large increase in the number of blue scales across the wing. This is due to an increase in the thickness of the scale lamina, creating a shift from brown/gold scales to blue scales. Credit: Rachel Thayer

Underside of artificially selected blue buckeye butterfly wing scales, showing their iridescent lamina colors. Credit: Rachel Thayer

First, the team showed that blueness in the selectively bred buckeye wings was, in fact, structural color and was generated largely by the lamina. They then compared these blue scales with wild-type brown scales, and found the same general architecture except the lamina was about 75 percent thicker in the blue scales. Finally, they measured lamina thickness in nine species of Junonia and a tenth species, Precis octavia, and found a consistent relationship with scale color.

“In each Junonia species, structural color came from the lamina. And they are producing a big range of lamina thicknesses that create a rainbow of different colors, everything from gold to magenta to blue to green,” says Thayer. “This helps us understand how structural color has evolved over millions of years.” The color shifts as lamina thickness increases according to Newton’s series, a characteristic color sequence for thin films, the team found.

Scale lamina thickness controls the color of scales. Upper left: wing from a bred blue buckeye; lower left: brown wing of a typical buckeye. Middle panel: Scales removed from these wings, showing the striking blue and gold colors respectively. Right: Scale cross-sections showing the lamina is 75% thicker for blue scales than for gold scales. Credit: Rachel Thayer

Comparison of buckeye wings – wild-type brown (right) and artificially selected blue (left). Credit: Aaron Pomerantz

“The color comes down to a relatively simple change in the scale: the thickness of the lamina,” says senior author Nipam Patel, director of the Marine Biological Laboratory. “We believe that this will be a genetically tractable system that can allow us to identify the genes and developmental mechanisms that can control structural coloration.” They identified one gene, optix, that can regulate lamina structural colors, and are currently searching for other candidates.

It was fortunate that the butterfly farmer, Edith Smith, had chosen buckeyes (Junonia coenia) for her mating experiment. For a variety of reasons, it is an ideal species for scientists to work with. “The buckeye genome is sequenced and other labs are working with it and have developed a number of experimental tools and protocols,” Patel says. “And it grows reasonably well in the lab, which is a big plus because many butterflies can be hard to raise.”

Smith’s bred buckeyes, which displayed “rapid evolution” from brown scales to blue, helped them to understand that the same, simple mechanism of tuning lamina thickness can facilitate evolutionary change that can span just several generations or millions of years.

Video by Emily Greenhalgh, MBL

Citation:

Rachel Thayer, Frances Allen and Nipam Patel (2020) Structural color in Junonia butterflies evolves by tuning scale lamina thickness. eLife, doi: 10.7554/eLife.52187

Homepage photo: Wild-type buckeye butterfly (Junonia coenia, left) compared to a mutant with the optix gene deleted (right). Credit Rachel Thayer

Videos of Blue and Green Buckeyes Bred at Shady Oak Butterfly Farm, Brooker, Florida:

https://www.youtube.com/watch?v=zsz2iBTmY5k
https://www.youtube.com/watch?v=Zh3I0R6sMlE

Rachel Thayer: http://www.patellab.net/portfolio-view/rachel-thayer/
Nipam Patel: http://www.patellab.net/

—###—

MBL Launches Digital Learning Initiative with “MBL SciShoots”

The coronavirus pandemic has everyone adapting and the Marine Biological Laboratory is no exception. With students unable to come to the campus to learn, MBL leadership has launched a new initiative to bring science to the students—virtually.

Watch the video below to learn all about our new educational series—MBL SciShoots—from MBL Director Nipam Patel. Be sure to follow along in the coming weeks to hear directly from MBL scientists and researchers as they share their science and answer your questions.

MBL SciShoots is targeted to the high-school education level. Videos will be posted one to two times per week on Tuesday and/or Thursday afternoons and followed by a comment-based Q&A with the video scientist.

You can find the videos on our YouTube page, by searching the hashtag #MBLSciShoots on social media, or by visiting our Facebook page.

A full list of videos and the scientist Q&As are available at: social.mbl.edu/tag/mblscishoots