Marine Biological Laboratory — Biological Discovery in Woods Hole

Deepening Diversity: First In-Depth Study of Marine Fungi and Their Reproduction Emerges from MBL

Contact: Diana Kenney
dkenney@mbl.edu; 508-289-7139

By Stephanie McPherson

Fungal colonies cultured from samples collected in various Woods Hole marine environments. Credit: Lorna Mitchison-Field

WOODS HOLE, Mass. -- Marine fungi have long been overlooked in the research community, despite their likely contributions to the health of ocean ecosystems. Now, a first deep dive into the diversity of marine fungi and their cell division cycles has been published by a collaborative team at the Marine Biological Laboratory (MBL), opening the door on this oft-neglected branch of the Kingdom Fungi.

“There's hardly anything known about fungi in the marine environment,” says Amy Gladfelter, MBL Fellow from the University of North Carolina at Chapel Hill and senior author on the new study, published in Current Biology. “This was an opportunity to understand who might be there and what they're doing, and also discover some new fungal systems that might display interesting biology.”

The paper describes 35 species of marine fungi collected from various sites around Woods Hole, many of which have never been studied before. The team found plenty of surprises, including unconventional cell division cycles in certain black fungi often found in extreme ocean environments.

“There's a lot of diversity in marine fungi—morphological and species diversity, possibly ecological functional diversity—that we don't know a lot about yet. And it's really worth digging into,” says Lorna Mitchison-Field, first author on the paper.

The research project was borne from Gladfelter’s long-time interest in fungi and their cell biological processes, such as polarity and cell division. She partnered with Christine Field, Lecturer at Harvard University and MBL Whitman Center scientist, and Mitchison-Field, who was an undergraduate at Mount Holyoke College during the bulk of the project and spent their summers at MBL.

Mitchison-Field took advantage of the MBL’s Marine Resources Center to gather samples from local sites.

“We brought back samples from coastal water, marshes, beaches, and other environments and plated them out on different kinds of media with nutrients, hoping to culture fungi,” says Mitchison-Field. “Then I observed the colony growth through a period of usually one to two-and-a-half weeks. As they grew, I would pick specific colonies to isolate and we'd look at those using [time-lapse] differential interference contrast (DIC) microscopy.”

Lorna Mitchison-Field collecting water samples from Buzzards Bay with Scott Bennett of the MBL Marine Resources Center. Credit: Amy S. Gladfelter

A group of black yeast species proved particularly interesting. One species produced multiple buds per cell cycle, rather than the single bud seen in the classical model of fungal reproduction. Another species alternated its methods of reproduction, switching between fission and budding each cell-division cycle.

Being the first study of its kind, their paper is already making waves in cell biology. (See Commentary, here.)

“The reaction that we've gotten from cell biologists…is a sense of wonder,” says Gladfelter. “Like, ‘Wow, there's so much out there still that we don't know.’ We hope this inspires people to keep looking for new biology in this incredibly diverse biosphere that has only barely been studied.”

Because they found so many different types of fungi in such varied locations, the team hopes to study how fungi interact with their environments.

“One future hope is that we can start looking at fungi in the context of different hosts,” says Gladfelter, “taking not just a culture-based approach, but a metagenomics identification of everybody who's there and what sort of genes they're expressing.”

Mitchison-Field has spent many summers in Woods Hole with their parents, Christine Field and Tim Mitchison, longtime MBL Whitman Center scientists from Harvard University. This MBL collaboration with Gladfelter and several other visiting scientists allowed Mitchison-Field, while still an undergraduate, to strengthen field and lab work skills in a real-world setting, resulting in their first paper as a first author.

The black yeast Hortaea werneckii dividing by fission and budding (DIC microscopy).
Credit: Lorna M.Y. Mitchison-Field et al (2019) Current Biology, doi: 10.1016/j.cub.2019.08.050

Citation:

Lorna M.Y. Mitchison-Field et al (2019) Unconventional Cell Division Cycles from Marine-Derived Yeasts. Current Biology, doi: 10.1016/j.cub.2019.08.050

Commentary:

Corey A.H. Allard and James B. Moseley (2019) Cell Biology: Marine Yeasts Deepen the Sea of Diversity. Current Biology, doi: 10.1016/j.cub.2019.09.22

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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.

Embryology Course Image Wins Top Prize in Nikon Small World Contest

Contact: dkenney@mbl.edu; 508-289-7139

By Stephanie McPherson

WOODS HOLE, Mass.—A vibrantly colored image of a turtle embryo taken by two members of the Marine Biological Laboratory (MBL) community has won first place in the 45^th Nikon Small World International Photomicrography Competition. Teresa Zgoda and Teresa Kugler used fluorescence and stereo microscopy during the 2017 MBL Embryology course to capture the winning image in a masterful example of image-stitching. The competition is regarded as the leading forum for showcasing the beauty and complexity of life as seen through the light microscope.

This fluorescent turtle embryo image, captured in the 2017 MBL Embryology course by Teresa Zgoda and Teresa Kugler, has taken the top prize in the 2019 Nikon Small World Photomicrography Competition.

“[The Small World Competition] is a fantastic contest to share beautiful scientific imagery,” says Zgoda. Their turtle image competed against more than 2,000 other submissions to win the top prize.

“We placed the turtle embryo in a petri dish and autofluorescence was photographed using three wavelengths of light. The final image is a composite of hundreds of images, since the embryo was so large,” says Zgoda. They captured the images with a Zeiss Discovery v20 stereo microscope and used a technique called image-stitching to produce the final image.

Another Embryology course image drew the judges' attention: an octopus embryo taken by 2018 course student Martyna Lukoseviciute and MBL's Carrie Albertin landed in 19th place.

Both Zgoda and Kugler are passionate micro-photographers, saying it's a hobby that allows them to explore their dual passions of science and artistic pursuits. Their winning image exemplifies the blend of science and art Nikon Small World aims to bring to the public each year.

When they captured the winning image, Zgoda and Kugler were interns with the imaging company Zeiss, which is stationed at MBL to assist students enrolled in the MBL's Advanced Research Training courses in using Zeiss microscopes.

The partnership between MBL and commercial vendors of laboratory equipment, including powerful microscopes from Nikon, Zeiss and other companies, is critical to the success of these world-renown courses.

“We are honored to have MBL community members recognized by the Nikon International Small World Competition,” says MBL Director Nipam Patel. “MBL has a long history of being at the forefront of developing new approaches in imaging and applying those methods to biological problems and questions. We are grateful to the commercial vendors who help make that possible.”

The MBL’s inherently collaborative nature has long been fertile ground for scientific progress, and the development and use of cutting-edge scientific technology.

“You are exposed to so much wonderful science at the MBL,” says Zgoda. “The courses they run are so in depth and offer a plethora of different subjects to image.”

“Nikon is a leading brand in photography, and it means so much to me that they chose this image for first place," she says.

Zgoda and Kugler’s image will be on display at the MBL next summer as part of the Nikon Small World Exhibit, which is shown throughout North America at selected museums and centers for science. The MBL is the only Massachusetts stop on the exhibit tour.

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Hurricane Nicole Leaves Insight on Deep-Ocean Impacts in Her Wake

Contact: Diana Kenney
dkenney@mbl.edu; 508-289-7139

By Paul McDivitt

Hurricane Nicole bears down on Bermuda on Oct. 12, 2016. Credit: NASA Goddard MODIS Rapid Response Team

WOODS HOLE, Mass. -- In early October 2016, a tropical storm named Nicole formed in the middle of the Atlantic Ocean. It roamed for six days, reaching Category 4 hurricane status with powerful 140 mile-per hour-winds, before hitting the tiny island of Bermuda as a Category 3.

Hurricanes like Nicole can cause significant damage to human structures on land, and often permanently alter terrestrial landscapes. But these powerful storms also affect the ocean.

Scientists have a good understanding of how hurricanes impact the surface layer of the ocean, the sunlit zone, where photosynthesis can occur. Hurricanes’ strong winds churn colder water up from below, bringing nutrients such as nitrogen and phosphorus to the surface and stimulating short-lived algae blooms. However, until recently, we didn’t know much about how hurricanes impact the deep ocean.

A new study of Hurricane Nicole by researchers at the Marine Biological Laboratory (MBL), Woods Hole, and the Bermuda Institute of Ocean Sciences (BIOS) has provided novel insight on those impacts. Nicole had a significant effect on the ocean’s carbon cycle and deep sea ecosystems, the team reports.

Studying the deep ocean

The Oceanic Flux Program (OFP) has been continuously measuring sinking particles, known as marine snow, in the deep Sargasso Sea since 1978. It’s the longest-running time series of its kind.

Before hitting Bermuda, Hurricane Nicole passed right through the OFP site, about 50 miles southeast of Bermuda. This gave the scientists a unique opportunity to study how hurricanes impact the deep ocean.

To study the deep ocean, the OFP strings scientific equipment, including sediment traps, at various depths on a mooring line that extends up from a 2,000-pound anchor situated on the seafloor (2.8 miles below the surface).

Key findings

In the new study, published in Geophysical Research Letters, MBL and BIOS scientists provide the first direct evidence that hurricanes affect the ocean’s biological pump, a process in which living organisms transfer carbon from the surface to the deeper ocean layers and the seafloor.

High-velocity winds associated with Hurricane Nicole generated intense surface-ocean cooling and strong currents and underwater waves, some of which lasted more than two weeks. This significantly accelerated the biological pump, with the currents pushing nutrients into the surface layer, triggering an algae bloom.

At center, scientists Rut Pedrosa Pàmies (of MBL) and Maureen Conte (of MBL and BIOS) and crew of the R/V Atlantic Explorer recover a deep ocean sediment trap on the Oceanic Flux Program mooring in the Sargasso Sea. This sediment trap was attached to the mooring line at 3,200 meters depth and continuously sampled the sinking particle flux during a six-month deployment. A fresh white sample bottle rotates into position under the trap funnel every two weeks to provide a time-resolved record of the flux. (Credit: J.C. Weber)

The supercharged biological pump then rapidly funneled the organic material from the hurricane-induced algae bloom down into the deep ocean. This provided a big boost of food for marine life in the deep ocean where light doesn’t reach.

The scientists found substantial increases in fresh organic materials in sediment traps at 4,900 feet and 10,500 feet below the surface. Algae growth measurements at the OFP site after Hurricane Nicole’s passage were among the highest observed in October over the last 25 years.

"The surface and the deep ocean are really well connected in the aftermath of these powerful storms,” explained Rut Pedrosa Pàmies, a biogeochemist and oceanographer at MBL’s Ecosystems Center and first author of the study. “The material that is reaching those depths is crucial for the deep-ocean ecosystem.”

Long-term implications

Since 1980, seven Category 3 or greater hurricanes have passed within 186 miles of Bermuda. These hurricanes affected a total of more than 32,800 square miles of surface water, an area greater than the state of Maine.

Current climate models indicate that hurricane intensity could increase as human-induced global warming continues. This could expand the area of ocean disturbed by hurricanes, with implications for the ocean’s biogeochemical cycles and deep-ocean ecosystems.

Earth’s last frontier

Due to the extreme conditions of the deep ocean, this remarkable biome has been notoriously difficult for scientists to study. Additionally, due to difficulties of shipboard data collection in extreme weather conditions, the direct impacts of hurricanes are not well understood. Sediment traps like those used by the OFP are crucial to understanding their influence on the deep ocean.

When the OFP began in 1978, scientists were only able to collect a single cup of sinking particles every two months. “Now, we have biweekly sample resolution and sediment traps at three depths,” Pedrosa Pàmies said.

With the proliferation of new equipment and technologies to study the deep ocean, understanding this last frontier is finally within reach.

Citation: R. Pedrosa Pàmies, M.H. Conte, J.C. Weber and R. Johnson (2019) Hurricanes Enhance Labile Carbon Expert to the Deep Ocean. Geophys. Res. Lett. DOI: 10.1029/2019GL083719

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