This protistan grazing, which is a key mechanism for carbon transport and recycling in microbial food webs, exerts a higher predation pressure at hydrothermal vent sites than in the surrounding deep-sea environment, a new paper finds.

“Our findings provide a first estimate of protistan grazing pressure within hydrothermal vent food webs, highlighting the important role that diverse deep-sea protistan communities play in deep-sea carbon cycling,” according to the paper, Protistan grazing impacts microbial communities and carbon cycling ad deep-sea hydrothermal vents published in the Proceedings of the National Academy of Sciences (PNAS).

Protists serve as a link between primary producers and higher trophic levels, and their grazing is a key mechanism for carbon transport and recycling in microbial food webs, the paper states.

The research found that protists consume 28-62% of the daily stock of bacteria and archaea biomass within discharging hydrothermal vent fluids from the Gorda Ridge, which is located about 200 kilometers off the coast of southern Oregon. In addition, researchers estimate that protistan grazing could account for consuming or transferring up to 22% or carbon that is fixed by the chemosynthetic population in the discharging vent fluids. Though the fate of all of that carbon is unclear, “protistan grazing will release a portion of the organic carbon into the microbial loop as a result of excretion, egestion, and sloppy feeding,” and some of the carbon will be taken up by larger organisms that consume protistan cells, the paper states.

After collecting vent fluid samples from the Sea Cliff and Apollo hydrothermal vent fields in the Gorda Ridge, researchers conducted grazing experiments, which presented some technical challenges that needed to be overcome. For instance, “prepping a quality meal for these protists is very difficult,” said lead author Sarah Hu, a postdoctoral investigator in the Marine Chemistry and Geochemistry Department at the Woods Hole Oceanographic Institution (WHOI).

“Being able to do this research at a deep-sea vent site was really exciting because the food web there is so fascinating, and it’s powered by what’s happening at this discharging vent fluid,” said Hu, who was onboard the E/V Nautilus during the May-June 2019 cruise. “There is this whole microbial system and community that’s operating there below the euphotic zone outside of the reach of sunlight. I was excited to expand what we know about the microbial communities at these vents.”

Hu and co-author Julie Huber said that quantitative measurements are important to understand how food webs operate at pristine and undisturbed vent sites.

“The ocean provides us with a number of ecosystem services that many people are familiar with, such as seafood and carbon sinks. Yet, when we think about microbial ecosystem services, especially in the deep sea, we just don’t have that much data about how those food webs work,” said Huber, associate scientist in WHOI’s Marine Chemistry and Geochemistry Department.

Obtaining baseline measurements “is increasingly important as these habitats are being looked at for deep-sea mining or carbon sequestration. How might that impact how much carbon is produced, exported, or recycled?” she said.

“We need to understand these habitats and the ecosystems they support,” Huber said. “This research is connecting some new dots that we weren’t able to connect before.”

The research was supported by NASA, the National Oceanic and Atmospheric Administration, Ocean Exploration Trust, the National Science Foundation, and WHOI.

The feat, highlighted on the front cover of the latest issue of Science Advances, demonstrates a promising innovation in the field of soft robotics, which centers on creating new types of flexible, inflatable robots that are powered using water or air rather than electricity. The inherent safety and adaptability of soft robots has sparked interest in their use for applications like prosthetics and biomedical devices. Unfortunately, controlling the fluids that make these soft robots bend and move has been especially difficult — until now.

The key breakthrough by the team, led by University of Maryland assistant professor of mechanical engineering Ryan D. Sochol, was the ability to 3D print fully assembled soft robots with integrated fluidic circuits in a single step.

“Previously, each finger of a soft robotic hand would typically need its own control line, which can limit portability and usefulness,” explains co-first author Joshua Hubbard, who performed the research during his time as an undergraduate researcher in Sochol’s Bioinspired Advanced Manufacturing (BAM) Laboratory at UMD. “But by 3D printing the soft robotic hand with our integrated fluidic transistors, it can play Nintendo based on just one pressure input.”

As a demonstration, the team designed an integrated fluidic circuit that allowed the hand to operate in response to the strength of a single control pressure. For example, applying a low pressure caused only the first finger to press the Nintendo controller to make Mario walk, while a high pressure led to Mario jumping. Guided by a set program that autonomously switched between off, low, medium, and high pressures, the robotic hand was able to press the buttons on the controller to successfully complete the first level of Super Mario Bros. in less than 90 seconds.

“Recently, several groups have tried to harness fluidic circuits to enhance the autonomy of soft robots,” said recent Ph.D. graduate and co-first author of the study Ruben Acevedo, “but the methods for building and integrating those fluidic circuits with the robots can take days to weeks, with a high degree of manual labor and technical skill.”

To overcome these barriers, the team turned to “PolyJet 3D Printing,” which is like using a color printer, but with many layers of multi-material ‘inks’ stacked on top of one another in 3D.

“Within the span of one day and with minor labor, researchers can now go from pressing start on a 3D printer to having complete soft robots — including all of the soft actuators, fluidic circuit elements, and body features — ready to use,” said study co-author Kristen Edwards.

The choice to validate their strategy by beating the first level of Super Mario Bros. in real time was motivated by science just as much as it was by fun. Because the video game’s timing and level make-up are established, and just a single mistake can lead to an immediate game over, playing Mario provided a new means for evaluating soft robot performance that is uniquely challenging in a manner not typically tackled in the field.

In addition to the Nintendo-playing robotic hand, Sochol’s team also reported terrapin turtle-inspired soft robots in their paper. The terrapin happens to be UMD’s official mascot, and all of the team’s soft robots were printed at UMD’s Terrapin Works 3D Printing Hub.

Another important benefit of the team’s strategy is that it’s open source, with the paper open access for anyone to read as well as a link in the supplementary materials to a GitHub with all of the electronic design files from their work.

“We are freely sharing all of our design files so that anyone can readily download, modify on demand, and 3D print — whether with their own printer or through a printing service like us — all of the soft robots and fluidic circuit elements from our work,” said Sochol. “It is our hope that this open-source 3D printing strategy will broaden accessibility, dissemination, reproducibility, and adoption of soft robots with integrated fluidic circuits and, in turn, accelerate advancement in the field.”

At present, the team is exploring the use of their technique for biomedical applications including rehabilitation devices, surgical tools, and customizable prosthetics. As Sochol is a faculty affiliate of the Fischell Department of Bioengineering as well as a member of both the Maryland Robotics Center and the Robert E. Fischell Institute for Biomedical Devices, the team has an exceptional environment to continue advancing their strategy to address pressing challenges in biomedical fields.

“These findings do not support the routine use of azithromycin for outpatient SARS-CoV-2 infection,” said lead author Catherine E. Oldenburg, ScD, MPH, an assistant professor with the UCSF Proctor Foundation. SARS-CoV-2 is the virus that causes COVID-19.

Azithromycin, a broad-spectrum antibiotic, is widely prescribed as a treatment for COVID-19 in the United States and the rest of the world. “The hypothesis is that it has anti-inflammatory properties that may help prevent progression if treated early in the disease,” said Oldenburg. “We did not find this to be the case.”

The study, which was conducted in collaboration with Stanford University, appears July 16, 2021, in the Journal of the American Medical Association.

The study included 263 participants who all tested positive for SARS-CoV-2 within seven days before entering the study. None were hospitalized at the time of enrollment. In a random selection process, 171 participants received a single, 1.2 gram oral dose of azithromycin and 92 received an identical placebo.

At day 14 of the study, 50 percent of the participants remained symptom free in both groups. By day 21, five of the participants who received azithromycin had been hospitalized with severe symptoms of COVID-19 and none of the placebo group had been hospitalized.

The researchers concluded that treatment with a single dose of azithromycin compared to placebo did not result in greater likelihood of being symptom-free.

“Most of the trials done so far with azithromycin have focused on hospitalized patients with pretty severe disease,” said Oldenburg. “Our paper is one of the first placebo-controlled studies showing no role for azithromycin in outpatients.”

Co-authors included Jessica Brogdon, MPH&TM; Cindi Chen, MS; Kevin Ruder; Lina Zhong; Fanice Nyatigo; Catherine A. Cook, MPH; Armin Hinterwirth, PhD; Elodie Lebas, RN; Travis Redd, MD, MPH; Travis C. Porco, PhD, MPH; Thomas M. Lietman, MD; and Benjamin F. Arnold, PhD, MPH, all of UCSF; senior investigator Thuy Doan, MD, PhD, with the UCSF Proctor Foundation, and Benjamin A. Pinsky, MD, PhD, of Stanford University.

The trial was supported by the Bill and Melinda Gates Foundation (INV-017026). Azithromycin and matching placebo were donated by Pfizer, Inc. (New York, NY). Thuy Doan was supported in part by a Research to Prevent Blindness Career Development Award. The authors had no conflicts of interest.

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Materials provided by University of California – San Francisco. Original written by Elizabeth Fernandez. Note: Content may be edited for style and length.

A research team led by Professor Junsuk Rho, Ph.D. candidate Minkyung Kim, and Dr. Dasol Lee of POSTECH’s departments of mechanical engineering and chemical engineering, and a team led by Professor Heon Lee and Soomin of the Department of Materials Science and Engineering at Korea University have together developed a transparent radiative cooler that transmits visible light while reflecting near-infrared light, and radiates heat in the atmospheric window where the wavelength range is between 8 and 13 micrometers (?m). Recognized for its significance, this study was featured as the front cover paper of the latest issue of Advanced Optical Materials.

Radiative cooling is a technology that lowers the temperature of an object by absorbing less energy from the sun and emitting radiant heat. Conventional radiative cooling materials developed so far have been limited to transparent emitters that transmit all light under direct sunlight and opaque radiative coolers that reflect all solar energy. For this, transparency is an important characteristic in practical applications of radiative cooling, but the transmitted sunlight trapped in an inner space is generally the main cause of the increasing temperature.

The joint research team focused on developing a transparent radiative cooler to solve this problem. Taking advantage of the characteristics of light, the researchers proposed a material that can transmit visible light, reflect near-infrared light, and emit mid-infrared rays.

The radiative cooling material developed by the researchers in this study exhibits both transparency and radiative cooling effect by selectively reflecting near-infrared light. In an outdoor rooftop experiment, the researchers found that the interior temperature of the high-absorbing chamber in the cooler box was lowered by 14.4 °C and the temperature of the material itself was lowered by 10.1 °C even when paint was applied.

“The radiative cooler developed this time can be used as a window of a building or an observatory that needs to maintain transparency, or as a window in an amusement ride or a vehicle,” explained Professor Junsuk Rho of POSTECH. “It can even take on color because it retains its cooling effect when paint is applied to it.”

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A pressing question is how these sequestered chloroplasts retains their photosynthetic capability without algal nuclei. Since the genome of the algal nucleus encodes most of the proteins required for photosynthesis, chloroplasts isolated from algal cells instantly lose their photosynthetic capability. Nevertheless, algae-eating sea slugs retain this photosynthetic capability for months. There have been numerous debates about the mechanisms underlying the phenomenon of sequestered chloroplasts retaining photosynthetic capabilities over the long term. A widely accepted hypothesis accounting for kleptoplasty is the horizontal gene transfer of the photosynthesis genes from algae to sea slug.

A team of researchers at the National Institute for Basic Biology (NIBB), in addition to collaborators from seven other Japanese institutions, have published the genome of the sea slug, Plakobranchus ocellatus type black, in eLife. “Since the sea slug is a non-model organism, its genome analysis was very tough in comparison to model organisms such as the mouse and the fruitfly. Furthermore, there was no high-quality genetic information for them. This situation consequently hindered the verification of the hypothesis of algae-derived horizontal gene transfer,” said Shuji Shigenobu, a genome scientist and professor at NIBB who is the corresponding author of the paper, “But we succeeded in accurately revealing the genome information of the sea slug.” Scientists are ready to settle the arguments concerning the horizontal transfer of algal genes to the animal nucleus based on newly unveiled genome data. “We looked at the genome very carefully, but we found no evidence of photosynthetic genes encoded on the sea slug genome, ” he said.

“We are embarking upon a new challenge to answer the question: how does the sea slug retains this function without horizontal gene transfer?,” said Taro Maeda, the first and co-corresponding author of the paper. “Our genome data also provides clues to this. We have found several candidate genes related to the long-term maintenance of photosynthetic activity. These genes related to protein metabolism, oxidative stress tolerance, and innate immunity should be subsequently highlighted in future studies.”

The mechanisms underlying kleptoplasty are still elusive. Further understanding of this phenomenon may lead us to innovative biotechnologies, which, for example, could bestow photosynthetic abilities to other various animal cells in the future.

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While researchers have intensively studied the social structure of hyenas and other animals, it’s only recently that scientists have begun to investigate how this structure arises. A new study led by Penn biologists, which relies upon 27 years of detailed observations of hyena social behavior collected by researchers at Michigan State University, pulls back the curtain on how social order comes to be.

Their findings show that hyenas inherit their mother’s social networks, so their social connections resemble their mother’s. However, offspring of higher-ranking individuals more faithfully replicate their mother’s interactions, winding up with social networks that more closely resemble their mother’s than do offspring of females that rank lower on the clan’s social ladder. The team reported their findings in the journal Science.

“We knew that the social structure of hyenas is based in part on one’s rank in the agonistic hierarchy, which we know is inherited from mothers” says Erol Akçay, a study coauthor and associate professor in Penn’s School of Arts & Sciences. “But what we found, that affiliative, or friendly interactions, are also inherited, hadn’t been shown.”

“This is a very simple process of social inheritance that we show works very, very well,” says Amiyaal Ilany, a senior lecturer at Israel’s Bar-Ilan University. “Individuals that were born to higher rank are more accurate in their inheritance, and they have good reason to do so. It fits well with what is already known about inheritance of rank. There are very strict rules about what place you sit in the hierarchy if you are a hyena.”

The work builds on a theoretical model of social network inheritance Akçay and Ilany developed in 2016. According to that simple framework, animals establish their networks by “social inheritance,” or copying their mother’s behaviors. The model fit well with snapshots of real-world social networks from not only hyenas but also three other social species: bottle-nosed dolphins, rock hyrax, and sleepy lizards.

In the new work, the team aimed to refine their model to better understand the intricacies of social inheritance in hyenas. They were fortunate to have a robust dataset collected by Akçay and Ilany’s coauthor, zoologist Kay Holekamp of Michigan State University, consisting of 27 years of detailed accounting of a clan’s social interactions.

“We realized we could use that dataset to directly test our model, to see if social ties are inherited or not,” Akçay says.

Field biologists from Holekamp’s research group had meticulously tracked how hyenas in a clan interacted, including who spent time with whom as well as the social rank of each member. To do so, researchers spent months getting to know each member of the clan by sight.

“They are there year-round, every day, identifying individuals by their specific spot patterns and other characteristics,” Ilany says.

These observations allowed Akçay, Ilany, and Holekamp to map out hyenas’ social networks based on which individuals spent time close together.

“This use of proximity to track social networks isn’t possible with humans, as two strangers might randomly get into an elevator together,” Ilany says. “But with hyenas, if one individual gets within a few meters of another, that suggests that they have a social connection.”

With this picture of each individual’s social affiliations in hand, the researchers compared the social networks of mothers to their offspring. “We developed a new metric to measure social inheritance, to track how faithfully an offspring’s network reproduces its mother’s network,” Akçay says.

Hyena cubs stick close to their mothers for the first couple years of life, so the networks of mothers and their offsprings were quite similar to start. However, the researchers noticed that even as the young stopped spending so much time in close proximity to their mothers they still sustained quite similar networks, particularly for female offspring, who generally remain members of the clan for life. “We have data in some cases showing that the network similarity between mothers and offspring, especially female offspring, was still very high after six or so years,” says Ilany. “You may not be seeing your mother as often, or she even may have died, but you still have similar friends.”

This pattern was especially strong for the higher-ranking mothers, for whom social inheritance was the strongest in the group.

“That is kind of intuitive because things like that happen in human society as well,” Akçay says. “It happens so much we take it for granted. We inherit social connections, and there’s a lot of social science research that shows that this has a huge influence on people’s life trajectory.”

Offspring of lower-ranking mothers were less likely to reproduce their mother’s social networks, perhaps trying to compensate for their more lowly origins by associating with a greater variety of individuals.

There is no genetic inheritance of rank or close associates in this species, so in Holekamp’s opinion one of the most remarkable things about the phenomenon documented here is that the youngsters’ relationships with their mothers’ close associates are all learned very early in life. One explanation for why inheritance of social networks works better for high- than for low-ranking hyenas may be that low-ranking females tend to go off on their own more often to avoid competition with higher-ranking hyenas, so their cubs have fewer learning opportunities than cubs of high-ranking females.

Mother-offspring pairs with more similar social networks also lived longer, the team found. This effect on survivorship may owe to the fact that offspring who spend more time with their mothers and thus replicate their social networks benefit from the increased care.

Social rank also had an effect on survivorship and reproductive success.

“Rank is super important,” says Akçay. “If you’re born to a lower-ranked mother, you are less likely to survive and to reproduce.”

The researchers note that social network inheritance likely contributes to a group’s stability and also has implications for how behaviors are learned and spread through groups.

The study also underscores how factors other than genetics hold sway in key evolutionary outcomes, including reproductive success and overall survival. “A lot of things that are considered by default to be genetically determined may depend on environmental and social processes,” says Ilany.