The time is ripe! An innovative contactless method for the timely harvest of soft fruits

Scientists develop convenient technique to measure ripeness using laser-induced plasma shockwaves and the ensuing vibrations on the fruit's surface

SHIBAURA INSTITUTE OF TECHNOLOGY

Research News

 

IMAGE: A PULSED LASER IS FOCUSED BY A LENS ONTO A POINT CLOSE TO THE SURFACE OF THE FRUIT. THE LASER-INDUCED PLASMA CREATES A SHOCKWAVE THAT EXCITES RAYLEIGH WAVES ON THE... view more 

CREDIT: SHIBAURA INSTITUTE OF TECHNOLOGY

Most people are probably familiar with the unpleasant feeling of eating overripe or underripe fruit. Those who work in agriculture are tasked with ensuring a timely harvest so that ripeness is at an optimal point when the fruit is sold, both to minimize the amount of fruit that goes to waste and maximize the quality of the final product. To this end, a number of techniques to assess fruit ripeness have been developed, each with their respective advantages and disadvantages depending on the type of produce.

Although biochemical and optical methods exist, mechanical techniques are the most widely used. They indirectly assess ripeness based on the fruit's firmness. In turn, firmness is quantified by observing the vibrations that occur on the fruit when mechanical energy is accurately delivered through devices such as hammers, pendulums, or speakers. Unfortunately, these approaches fall short for softer fruits, which are more readily damaged by the contact devices used.

In a recent study published in Foods, a team of scientists from Shibaura Institute of Technology (SIT), Japan, addressed this issue through an innovative method for measuring the firmness of soft fruits using laser-induced plasma (LIP). This work is a sort of follow-up of a previous study in which LIP was used to quantify the firmness of harder fruits.

But what is LIP and how is it used? Plasma is a state of matter similar to the gaseous state but in which most particles have an electric charge. This energetic state can be produced in normal air by focusing a high-intensity laser beam onto a small volume. Because the generated plasma "bubble" is unstable, it immediately expands, sending out shockwaves at ultrasonic speeds. Professor Naoki Hosoya and colleagues at SIT had successfully used LIP shockwaves generated close to the surface of apples to excite a type of vibration called 0S2 mode, colloquially referred to as "football mode vibration" because of how the resulting deformation looks on spherical bodies. They then verified that the frequency of the 0S2 mode vibrations was correlated with the firmness of the fruit.

However, soft fruits do not exhibit 0S2 mode vibrations, so the team had to analyze an alternative type of oscillation: Rayleigh waves. These are waves that occur exclusively on the surface of bodies without penetrating far into the interior. Using Kent mangoes, a setup for generating LIP, and commercially available laser-based vibrometers, the scientists verified that the velocity at which Rayleigh waves propagate is directly related to the firmness of the mangoes. Because the propagation velocity markedly decreases with storage time, it provides a reliable way to indirectly assess ripeness.

The team went further and looked for the best position on the mangoes' surface to determine the velocity of Rayleigh waves. Mangoes, as well as other soft fruits, have large seeds inside, which can alter the propagation of surface waves in ways that are detrimental to measurements. "The results of our experiments indicate that Rayleigh waves along the 'equator' of the mango are better for firmness assessment compared to those along the 'prime meridian'," explains Hosoya. The experiments also revealed that cavities within the fruit's flesh or decay can greatly affect the results of the measurements. Thus, as Hosoya adds, they will keep investigating which is the best area to measure firmness in mangoes using their novel approach.

In short, the team at SIT has engineered an innovative strategy to assess the ripeness of soft fruits from outside. "Our system," remarks Hosoya, "is suitable for non-contact and non-destructive firmness assessment in mangoes and potentially other soft fruits that do not exhibit the usual 0S2 mode vibrations." Further refinement of such firmness assessment methods will hopefully make them more reliable and accessible for the agricultural industry. With any luck, their widespread adoption will ensure that fruits reach your plate only when the time is ripe!

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Reference

Title of original paper: Soft Mango Firmness Assessment Based on Rayleigh Waves Generated by a Laser-Induced Plasma Shock Wave Technique
Journal: Foods
DOI: 10.3390/foods10020323

About Shibaura Institute of Technology (SIT), Japan

Shibaura Institute of Technology (SIT) is a private university with campuses in Tokyo and Saitama. Since the establishment of its predecessor, Tokyo Higher School of Industry and Commerce, in 1927, it has maintained "learning through practice" as its philosophy in the education of engineers. SIT was the only private science and engineering university selected for the Top Global University Project sponsored by the Ministry of Education, Culture, Sports, Science and Technology and will receive support from the ministry for 10 years starting from the 2014 academic year. Its motto, "Nurturing engineers who learn from society and contribute to society," reflects its mission of fostering scientists and engineers who can contribute to the sustainable growth of the world by exposing their over 8,000 students to culturally diverse environments, where they learn to cope, collaborate, and relate with fellow students from around the world.

Website: https://www.shibaura-it.ac.jp/en/

About Professor Naoki Hosoya from SIT, Japan

Dr. Naoki Hosoya currently leads the Mechanical Dynamics Laboratory at SIT, where he performs research on various topics within the field of mechanical engineering, including vibration analysis and engineering, structural dynamics, soft actuators, non-destructive tests, and acoustic and modal analysis. He has authored over 140 published papers, some of which have been among the top 10 most read in their respective journals.

Funding Information

This study was partly supported by the Tojuro Iijima Foundation for Food Science and

Technology, grant number 25, and the Japan Society for the Promotion of Science for their support under Grants-in-Aid for Scientific Research Programs (Grants-in-Aid for Scientific Research (B), Project No. JP 19H02088).

Disclaimer: AAAS and EurekAlert! are not res

Reinforced by policies, charters segregate schools

CORNELL UNIVERSITY

Research News

 

ITHACA, N.Y. - The expansion of charter schools in the 2000s led to an increase in school segregation and a slight decline in residential segregation, according to new research from Cornell University providing the first national estimates of the diverging trends.

According to the study, the average district to expand charter school enrollment between 2000 and 2010 experienced a 12% increase in white-Black school segregation and a 2% decrease in white-Black residential segregation.

The patterns moved in opposite directions, the research found, because charter schools - which receive public funds but operate independently - weaken the traditional link between neighborhood and school assignment, allowing families to choose more racially homogenous schools regardless of where they live.

The findings highlight education policy's influence beyond schools and offer a "cautionary lesson" about continued charter expansion without efforts to limit racial sorting by families, according to lead author Peter Rich.

Understanding charter schools' effects on segregation is critical, because they represent an increasingly popular educational reform, the researchers said. Charter school enrollment has quadrupled since 2000, serving nearly 6% of students in 2015-2016, and is expected to continue growing and gaining influence.

The researchers analyzed more than 1,500 metropolitan school districts to examine what happened when school choice decoupled neighborhood and school options, using data from the census and the National Center for Education Statistics' Common Core of Data.

The researchers said their findings reveal school and residential segregation as "more like eddies in a stream, circling and reinforcing each other via policies and preferences."

The analysis did not find that charter school affected white-Hispanic segregation in schools, because Hispanic students on average attend more diverse charter schools. White-Hispanic segregation did fall as charter enrollment grew.

Though the reductions in residential segregation were "nontrivial," the researchers said, policy makers should not see school choice as a tool for achieving resident diversity, given how it exacerbated school segregation.

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The study, "Segregated Neighborhoods, Segregated Schools: Do Charters Break a Stubborn Link?" published March 1 in the journal Demography.

For additional information, see this Cornell Chronicle story.

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Natural product isolated from sea sponge tested against cancer cells

FAR EASTERN FEDERAL UNIVERSITY

Research News 

IMAGE: FEFU LAB FOR DNA DIAGNOSTICS, EQUIPMENT view more 

CREDIT: FEFU PRESS OFFICE

Scientists from Far Eastern Federal University (FEFU) together with Russian and German colleagues, continue studying antitumor compounds synthesized based on bioactive molecules isolated from a sea sponge. One of them fights cancer cells resistant to standard chemotherapy, and at the same time has an interesting dual mechanism of action. A related article appears in Marine Drugs.

Scientists have tested the biological effect of the marine alkaloid 3,10-dibromofascaplysin on various prostate cancer cells, including those resistant to standard docetaxel-based chemotherapy. The compound was first isolated from the sea sponge Fascaplysinopsis reticulata and subsequently chemically synthesized in FEFU. The substance forces tumor cells to die via a programmed cell death mechanism. This process is called "apoptosis" and is considered the most favorable mode of action of anticancer drugs.

"The examined compound, while killing cancer cells, even ones resistant to standard chemotherapy, simultaneously activates an enzyme (so-called «kinase») protecting these tumor cells. However, it can't be considered as a "good" or "bad" effect. This is just a mechanism of action, an understanding of which suggests us to apply 3,10-dibromofascaplysin together with inhibitors of these enzymes," says Dr. Sergey Dyshlovoy, from the Laboratory of biologically active substances of FEFU School of Natural Sciences, senior researcher in the laboratory of the pharmacology of National Scientific Centre of Marine Biology (Vladivostok, Russia).

According to the scientist, the synthesized compound in addition to its own activity, works well in combination with several already approved anticancer drugs, enhancing their antitumor effect.

Next, scientists are planning to examine how 3,10-dibromofascaplysin affects non-cancer cells. They already run a related project supported by the Russian Foundation for Basic Research, aiming to report the outcomes during 2021.

"Fascaplysins are rather toxic to non-cancer cells. In our laboratory, we are trying to modify the structure of these compounds in order to reduce their cytotoxic effect on normal cells, while maintaining the necessary antitumor effect. The goal is to create a substance for targeted therapy, with a minimum of side effects for healthy cells of the body," says Dr. Maxim Zhidkov, Head of Department of Organic Chemistry, FEFU School of Natural Sciences.

Commented on the time needed for the development of the on-the-shelf drug, scientists speak about the horizon of 10-15 years, given the necessity for long preliminary and further clinical trials.

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In the study took part specialists from the Far Eastern Federal University, A.V. Zhirmunsky National Scientific Center of Marine Biology (RAS, Vladivostok), Martini Clinic (Germany), University Medical Center Hamburg-Eppendorf (Germany), V.N. Orekhovich Research Institute of Biomedical Chemistry (Russian Academy of Sciences), V.A. Engelhardt Institute of Molecular Biology (RAS, Moscow).

The World Ocean is one of the priority research run in the FEFU. University scientists conduct research on bioactive molecules of marine origin, develop engineering solutions for Arctic ice platforms (exploration and production of minerals), underwater robotics, under-ice communications, etc.

On calm days, sunlight warms the ocean surface and drives turbulence

OREGON STATE UNIVERSITY

Research News

 

IMAGE: CLOUDS FORM OVER THE INDIAN OCEAN AS THE SUN SETS. A NEW STUDY HAS FOUND THAT IN TROPICAL OCEANS, A COMBINATION OF SUNLIGHT AND WEAK WINDS DRIVES UP SURFACE TEMPERATURES... view more 

CREDIT: DEREK COFFMAN, NOAA.

CORVALLIS, Ore. - In tropical oceans, a combination of sunlight and weak winds drives up surface temperatures in the afternoon, increasing atmospheric turbulence, unprecedented new observational data collected by an Oregon State University researcher shows.

The new findings could have important implications for weather forecasting and climate modeling, said Simon de Szoeke, a professor in OSU's College of Earth, Ocean, and Atmospheric Sciences and the lead author of the study.

"The ocean warms in the afternoon by just a degree or two, but it is an effect that has largely been ignored," said de Szoeke. "We would like to know more accurately how often this is occurring and what role it may play in global weather patterns."

The findings were just published in the journal Geophysical Research Letters. Co-authors are Tobias Marke and W. Alan Brewer of the NOAA Chemical Sciences Laboratory in Boulder, Colorado.

Over land, afternoon warming can lead to atmospheric convection and turbulence and often produces thunderstorms. Over the ocean, the afternoon convection also draws water vapor from the ocean surface to moisten the atmosphere and form clouds. The warming over the ocean is more subtle and gets stronger when the wind is weak, said de Szoeke.

De Szoeke's study of ocean warming began during a research trip in the Indian Ocean several years ago. The research vessel was equipped with Doppler lidar, a remote sensing technology similar to radar that uses a laser pulse to measure air velocity. That allowed researchers to collect measurements of the height and strength of the turbulence generated by the afternoon warming for the first time.

Previous observations of the turbulence over the ocean had been made only by aircraft, de Szoeke said.

"With lidar, we have the ability to profile the turbulence 24 hours a day, which allowed us to capture how these small shifts in temperature lead to air turbulence," he said. "No one has done this kind of measurement over the ocean before."

Researchers gathered data from the lidar around the clock for about two months. At one point, surface temperatures warmed each afternoon for four straight days with calm wind speeds, giving researchers the right conditions to observe a profile of the turbulence created in this type of sea surface warming event.

It took a "perfect storm" of conditions, including round-the-clock sampling by the lidar and a long ocean deployment, to capture these unprecedented observations, de Szoeke said.

Sunlight warms the ocean surface in the afternoon, surface temperatures go up by a degree Celsius or more. This warming occurs during roughly 5% of days in the world's tropical oceans. Those oceans represent about 2% of the Earth's surface, about the equivalent of the size of the United States.

The calm wind and warming air conditions occur in different parts of the ocean in response to weather conditions, including monsoons and Madden-Julian Oscillation, or MJO, events, which are ocean-scale atmospheric disturbances that occur regularly in the tropics.

To determine the role these changing temperatures play in weather conditions in the tropics, weather models need to include the effects of surface warming, de Szoeke said.

"There are a lot of subtle effects that people are trying to get right in climate modeling," de Szoeke said. "This research gives us a more precise understanding of what happens when winds are low."

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The research was supported by NOAA and the Office of Naval Research.

Socioeconomic status plays a major role in cognitive outcomes

Childhood cancer and its treatment can result in cognitive struggles. St. Jude scientists are studying the risk factors.

ST. JUDE CHILDREN'S RESEARCH HOSPITAL

Research News

IMAGE: HEATHER CONKLIN, PHD, OF ST. JUDE PSYCHOLOGY, CONTRIBUTED TO RESEARCH THAT STUDIED RISK FACTORS OF CERTAIN CANCER TREATMENTS IN CHILDREN. view more 

CREDIT: ST. JUDE CHILDREN'S RESEARCH HOSPITAL

Childhood cancer and its treatment can result in cognitive struggles. Scientists atSt. Jude Children's Research Hospital are studying the risk factors. They looked at social and economic issues in children with brain tumors treated with radiation.

These patients have the greatest risk of cognitive problems. Scientists followed a group of St. Jude patients for 10 years. The children all had conformal radiation therapy.

For each patient, researchers looked at certain factors. These included the parent's job, education level, and whether it was a single parent home. The children were from different backgrounds.

The findings show social and economic status is linked to IQ, academics, attention and self-care skills before treatment. The study also shows that this gap widens over time.

"What was most surprising was that for some measures, the contribution of socioeconomic status was even greater than age at treatment, which has typically been the biggest risk factor," said Heather Conklin, PhD, of St. Jude Psychology.

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Neuro-Oncology published a report on this work

Black Americans report high levels of vaccine hesitancy

Hesitancy also high among Black health Care workers

RAND CORPORATION

Research News

Black Americans have a high level of vaccine hesitancy and mistrust of COVID-19 vaccines, including among Black health care workers, according to a new RAND Corporation survey.

Those who expressed vaccine hesitancy also showed high levels of overall mistrust in the vaccine, concerns about potential harm and side effects, and lack of confidence in vaccine effectiveness and safety.

Participants in the RAND survey reported higher trust in COVID-19 information from health care providers and public health officials than from elected local and federal officials.

The findings are based on a survey of 207 Black Americans who are participants in the RAND American Life Panel, a nationally representative internet panel. Participants were surveyed during November and December 2020.

"Public health messages and communication strategies to address vaccine hesitancy should be tailored through authentic community engagement," said Laura M. Bogart, the study's lead author and a senior behavioral scientist at RAND, a nonprofit research organization. "Messaging about COVID-19 vaccines should first acknowledge systemic racism as a justifiable reason for mistrust before providing transparent information about the vaccine, including specific information about efficacy and safety."

The survey found that mistrust of the government's motives and transparency around COVID-19, as well as beliefs about racism in health care, appear to be contributing to mistrust of the vaccine. In addition, the more participants believed that people close to them would want them to get vaccinated, the more likely they were to say that they would get vaccinated themselves.

Black Americans attribute their medical mistrust, in general and specific to COVID-19 vaccines, to systemic racism, including discrimination and mistreatment in health care, as well as by the government.

Overall, more than one-third of all survey participants agreed or strongly agreed that they would not get a COVID-19 vaccine, and an additional 25% said they "don't know" if they would become vaccinated. Only 40% indicated that they planned to get vaccinated.

Participants in health care fields, including health care practitioners and those in technical and support occupations, showed higher vaccine hesitancy. Specifically, 48% of participants in health care fields indicated that they would not get vaccinated, compared with 32% of participants who were not in health care-related occupations.

When asked about which sources they trusted for information about COVID-19, nearly two-thirds of all respondents said that they trusted health care professionals such as doctors and nurses. Health care providers were trusted by higher percentages of participants who said that they would get the vaccine (72%) than those who said that they would not (56%).

Participants said that public health campaigns should involve trusted, known community members and trusted local organizations. Some participants suggested partnerships with Black celebrities such as hip-hop artists to encourage vaccination.

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The study, "What Contributes to COVID-19 Vaccine Hesitancy in Black Communities, and How Can It Be Addressed?," is available at http://www.rand.org.

Other authors of the study are Lu Dong, Priya Gandhi, Samantha Ryan, Terry L. Smith, David J. Klein, Luckie Alexander Fuller and Bisola O. Ojikutu.

RAND Health Care promotes healthier societies by improving health care systems in the United States and other countries.

Deep dive into bioarchaeological data reveals Mediterranean migration trends over 8,000 years

FLORIDA STATE UNIVERSITY

Research News

IMAGE: THOMAS LEPPARD IS AN ASSISTANT PROFESSOR OF ANTHROPOLOGY AT FLORIDA STATE UNIVERSITY. view more 

CREDIT: FSU PHOTOGRAPHY SERVICES

A team of international researchers led by a Florida State University assistant professor has analyzed reams of data from the Neolithic to Late Roman period looking at migration patterns across the Mediterranean and found that despite evidence of cultural connections, there's little evidence of massive migration across the region.

"Because of the prevailing scholarly attitude of the 'connected' Mediterranean -- one with high degrees of mobility and migration that drive the archaeological patterns we see -- we'd imagined we'd see comparatively high levels of migration reflected in the strontium isotope data," said Thomas Leppard, assistant professor of anthropology at Florida State. "That instead we saw low levels of migration, and that these in fact decreased over time, was very surprising."

Leppard and his colleagues found that from about 7,500 BC to AD 500, migration rates ranged from about 6% to 9% of the population within the dataset. These rates seem to have decreased over time.

The research is published in the Journal of Mediterranean Archaeology.

Many historians and archaeologists consider the Mediterranean basin to have been interconnected for much of its history. However, that theory is largely built on material culture that suggests such connections - for example, Greek-looking pots in Sicily in the Late Bronze Age, Arabic coins in Medieval Sardinia, or Roman-style dining sets in 2nd century AD Portugal.

Leppard wondered if the same pattern would be obvious if they brought human biochemistry into the mix.

For several years, scientists have been able to understand individual life histories by analyzing the chemistry of human remains. In humans, bodily tissues, including most bones, remake themselves constantly so that their chemical composition reflects their current environment. However, dental enamel and a small skull bone called the petrous portion are extremely hard and don't remodel, so once a human reaches adulthood, the isotope ratios in those two areas of the body don't change.

"As a result, if you spend childhood somewhere, and then move as an adult to a different place with different underlying chemistry, we can see a difference in the chemistry - and critically in the ratios of different strontium isotopes - between your dental enamel and your other bones," Leppard said. "If, however, you grew up and died in the same location, the ratios will be the same. That means we can start to quantify percentages of locals, and percentages of nonlocals in a given area."

Archaeologists have employed this technique for a while in the Mediterranean, but the sample sizes are generally very small because the experiments are expensive and there often aren't many samples of human remains. Leppard and his colleagues compiled all the data from many smaller experiments capturing a large time frame and re-analyzed it.

He cautioned that this is a starting place to assess the migration patterns of this region.

"It's important to say that migration is only one aspect of human mobility; we can't access seasonal or habitual mobility with this method, for example," Leppard said. "That said, we thought this would be a powerful method for assessing large-scale trends in Mediterranean migration across time. That these trends don't really match the current scholarship should generate productive debate and prompt new research."

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Leppard's co-authors are Carmen Esposito, a doctoral student at Queen's University in Belfast; and Massimiliano Esposito, a former doctoral student from Imperial College London.

A research group proposes six guidelines for managing the impacts of invasive species

Researchers in Brazil, Argentina, Chile, and the UK are participating in the initiative; results are published in the journal BioScience

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO

Research News

 

IMAGE: PHOTOGRAPHS SHOWING A NON-INVADED AREA [LEFT] AND AN AREA INVADED BY UROCHLOA BRIZANTHA [PALISADE GRASS, RIGHT] / GABRIELLA DAMASCENO) view more 

CREDIT: GABRIELLA DAMASCENO

 Invasive alien species, defined as animals and plants that breed and disperse in a landscape beyond their native range, have negative environmental, social, and economic impacts. One example among many is the forage grass genus Brachiaria, originally African and introduced to Brazil to form cattle pasture. It has become a major threat to the survival of native species and biodiversity at several spatial scales. 

Complete eradication of invasive species is often impracticable. Attempts to do so have had undesirable consequences and even been damaging because merely withdrawing an invasive species does not restore the original environment, as in the areas of Cerrado (Brazilian savanna) invaded by pines. Instead of eradication, therefore, the goal should be continuous management, according to many experts. This is the line taken by researchers from Brazil, Argentina, Chile, and the United Kingdom, who have agreed on a strategic approach focusing on impact mitigation rather than elimination.

They call their project CONTAIN Latam. The name refers to the impossibility of eradicating invasive non-native species and the need for containment of their growth and impacts. 

The project resulted from a 2018 call for proposals issued under the aegis of a cooperation agreement involving FAPESP, the UK Natural Environment Research Council (NERC), UK Research and Innovation (UKRI), the Newton Fund, Argentina's National Scientific and Technical Research Council (CONICET), Chile's National Commission for Scientific and Technological Research (CONICYT), and Peru's National Council for Science, Technology and Technological Innovation (CONCYTEC).

The initiative aims at developing management tools to optimize the control of invasive species in the medium to long term. The Brazilian members of the group are affiliated with São Paulo State University (UNESP) and coordinated by Alessandra Fidelis, a professor in UNESP's Rio Claro Institute of Biosciences.

A study by the CONTAIN group is the subject of an article published recently in the journal BioScience. The study was supported by FAPESP via a research project for which Fidelis is principal investigator in Brazil.

"Our study set out not just to analyze invasive species but also to put forward guidelines for interaction with managers with the aim of containing proliferation of these species and mitigating their impacts," Fidelis told Agência FAPESP.

The full definition stated early on in the article is that invasive species "successfully transition the three initial invasion stages (transport, introduction, and establishment) and subsequently establish multiple self-sustaining populations composed of individuals that breed, survive and disperse in a landscape beyond their native range", and that a "subset" of invasive species produces an array of "negative environmental, social, and economic impacts at various spatial scales". 

In this vast subset, the project focuses on the following: in Brazil, Brachiaria spp., Urochloa spp. and other grasses of African origin introduced as forage crops for cattle pasture, and pines (Pinus spp.) introduced from the northern hemisphere for reforestation and to produce pulp and resin; in Argentina, American mink (Neovison vison)  introduced for fur production, pines, and privet (Ligustrum spp.), of Asian origin and introduced here as a street tree, hedge or ornamental plant; in Chile, pines, mink, and the Yellowjacket or German wasp (Vespula germanica) whose origin is hitherto unknown.

"We propose six criteria for planning to mitigate their impacts. The first three comprise a detailed survey of the situation: mapping their presence and spatial distribution, finding out how long each invasive species has been present and compiling the available data on their impacts," Fidelis said. "The next three relate to the recommended responses to the situation: the kinds of intervention that are technically, socially, and economically feasible, the potential negative consequences of these interventions, and a cost-benefit analysis of the interventions and their consequences."

The COVID-19 pandemic has shone a bright light on the risks of degrading the natural environment and the urgent need to implement science-based policies for controlling and mitigating these risks. "In the case of the species on which our study focused, there's a very strong additional reason for implementing such policies, as mink have been found to be transmitters of the novel coronavirus," Fidelis said.

All this will evidently be ineffectual unless the knowledge produced by universities and research institutions can cross over from academia to society in general, and especially to those responsible for managing public and private affairs.

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About São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at http://www.fapesp.br/en and visit FAPESP news agency at http://www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.

Stressed-out young oysters may grow less meat on their shells

Early exposure to heat and low oxygen makes oysters more vulnerable to same stressors later on

SMITHSONIAN

NEWS RELEASE 1-MAR-2021

Research News

 

IMAGE: EASTERN OYSTER (CRASSOSTREA VIRGINICA) TAKEN FROM THE CHOPTANK RIVER ON MARYLAND'S EASTERN SHORE. view more 

CREDIT: SARAH DONELAN

Early exposure to tough conditions--particularly warmer waters and nightly swings of low oxygen--could leave lasting scars on oysters' ability to grow meaty tissue. A team of biologists at the Smithsonian Environmental Research Center (SERC) reported the discovery in a new study, published online Feb. 26 in the journal Ecological Applications.

Eastern oysters in Chesapeake Bay live mostly in shallow tributaries. It's a rough environment for shellfish that can't move. During hotter months, oxygen levels can swing drastically, from perfectly healthy levels in the day to near zero at night. To save energy, some oysters react by focusing more on shell growth than tissue growth. That could pose a problem for anyone involved in the seafood industry.

"What we all of course want to eat at the raw bar is the oyster tissue," said Sarah Donelan, a SERC postdoctoral fellow and lead author of the new report. "Customers and restaurants might be less pleased if there's less tissue in what looks to be a large oyster."

Total oyster growth suffered most when oysters experienced low oxygen alone. But early exposure left marks that were far easier to miss. There, researchers discovered a sharp drop in how fast oysters grow tissue versus shell. Oysters invested more in growing their shells--and less in the succulent, slurpable tissue inside--when exposed to the double punch of low oxygen and warmer waters both early and later in life.

Scars That Lie Dormant

For this study, Donelan teamed up with SERC senior scientists Matt Ogburn and Denise Breitburg. Ogburn studies conservation of oysters and other fishery species in Chesapeake Bay. Breitburg specializes in how fish and shellfish cope with the many environmental dangers that can coexist in the Chesapeake.

"Low oxygen and warming waters are a real double whammy for marine organisms," Breitburg said. "Warmer water holds less oxygen and causes oxygen to decline faster. At the same time, cold-blooded animals like oysters and finfish require more oxygen at warmer temperatures."

Donelan, an evolutionary biologist, wanted to find out if exposure to threats when very young could shape oysters later in life. Nightly swings of low oxygen put a special brand of pressure on the shellfish.

"If it's always bad, they can evolve over time to cope with those poor conditions," Donelan said. "But especially for [immobile] organisms like oysters, these fluctuations can be very stressful."

Donelan ran her experiment in a small lab SERC scientists affectionately call "The Room of DOOM" (the acronym stands for "Dissolved Oxygen Oyster Mortality"). It is a cramped, dark room filled with aquaria where biologists mimic conditions in shallow Chesapeake waters. Donelan took 3,600 young oysters, each about 3 months old, and exposed them to four possible scenarios. Some oysters experienced hotter water temps, some experienced nightly swings of low oxygen, some received both, and some got neither. After 18 days, Donelan gave the oysters a rest.

At first the oysters did not look any worse for wear. All oysters were roughly the same size regardless of whether they had been in hot water, oxygen-starved water or perfectly normal water. When Donelan estimated each oyster's shell and tissue size, she did not find any significant differences either.

But the effects of stress may simply have lain dormant. After a two-month break, Donelan put half the oysters back into experimental tanks. When faced with the same rough conditions again, oysters that had suffered from both low oxygen and hotter waters in Phase One started showing signs of strain.

The oysters managed to grow to a respectable size. But Donelan noticed something odd: Compared to more pampered oysters, oysters that suffered both stressors twice grew their shells more than their tissue. Their tissue-versus-shell growth ratio was merely half that of oysters that escaped the early double exposure.

It was a troubling find, because for oysters and oyster farmers alike, the meaty tissue is what really matters.

CAPTION

In experimental tanks like this, Sarah Donelan simulated the effects of warmer water and low oxygen in Chesapeake Bay on Eastern oysters.

CREDIT

Sarah Donelan/Smithsonian Environmental Research Center

Ensuring A Safe Start

This raised a question for the biologists: Why would early exposure not toughen up the oysters instead? Donelan has spent her career watching animals adapt, and she's seen it work both ways. In this case, she suspects the combination of warming and low oxygen leaves a scar that does not easily heal.

"I think that there's likely a physiological change that's irreversible," Donelan said.

Perhaps a critical gene turned off--or turned on. Perhaps something in the oyster's microbiome shifted, making them less efficient at processing oxygen. Whatever went on behind the scenes, it pushed the oysters to grow their shells more than the tissue they need to survive and spawn more oysters.

Fortunately, oyster farmers have some options for protecting their stock. This could involve tracking oxygen levels in the water, to see which areas are vulnerable to low-oxygen swings. It could mean bubbling extra oxygen into oxygen-starved zones. For farmers with indoor systems, keeping young oysters in tanks and out of the field longer could offer more protection.

"Of course it's more of a time investment to have to move oysters around or look at dissolved oxygen profiles on your farm, but it could be worth it," Donelan said.

The key, she said, is to protect oysters while they are still young. Oysters that were not exposed to the warm water-low oxygen combo early in life fared much better when they faced the same combo later.

Meanwhile, oysters are not the only creatures that suffer these "carryover effects" from stress. They contain a telling message for conservationists: What other dangers could be headed off by protecting organisms while they are young?

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The study, titled "Context-dependent carryover effects of hypoxia and warming in a coastal ecosystem engineer," is available at https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/eap.2315. For images, a full copy of the report or to speak with the authors, contact Kristen Minogue at minoguek@si.edu or (314) 605-4315.

Supertest evaluates performance of engineering students in Russia, the United States, India, China

A test developed jointly by HSE University Moscow and Stanford University assessed student performance in mathematics, physics, critical thinking

NATIONAL RESEARCH UNIVERSITY HIGHER SCHOOL OF ECONOMICS

Research News

 

IMAGE: IGOR CHIRIKOV, AFFILIATED RESEARCHER AT THE HSE INSTITUTE OF EDUCATION view more 

CREDIT: IGOR CHIRIKOV

A group of researchers representing four countries summed up the results of the Supertest, a large-scale study of the academic performance of engineering students in Russia, China, India, and the United States. It is the first study to track the progress of students in computer science and electrical engineering over the course of their studies with regard to their abilities in physics, mathematics, and critical thinking and compare the results among four countries. The article about study in Nature Human Behavior.

The HSE Institute of Education played a key role not only in collecting and analyzing data from Russia, but also in developing uniform assessment tools in mathematics and physics for all countries. The Institute conducted a full range of psychometric studies in addition to substantiating the quality of the measurements and the comparability of results across different countries.

The Supertest was initiated by Stanford University, HSE University Moscow, the Educational Testing Service (ETS), and partner universities in China and India. The study authors include Prashant Loyalka, an Associate Professor at Stanford University and a leading researcher at the HSE International Laboratory for Evaluating Practices and Innovations in Education; Igor Chirikov a senior researcher at the Center for Studies in Higher Education at UC Berkeley and an affiliated researcher of the HSE Institute of Education; and Elena Kardanova and Denis Federyakin , leading researchers at the Centre for Psychometrics and Measurements in Education at the HSE.

More than 30,000 undergraduate students participated in the study. The researchers collected a sample of students from elite and large universities, roughly equal in number for each country. In Russia, the sample included students from six Project 5-100 universities and 28 other universities. Their skill development was measured three times: upon entering university, at the end of their second year, and at the end of their studies.

The task of the specialists of the HSE Centre for Psychometrics and Measurements in Education was to develop tests that had questions that would be neutral for students of different countries and would yield adequately comparable results across different countries. 'Over the course of analyzing the test results, we have proven that we were able to achieve both tasks,' said Centre Director Elena Kardanova. 'Testing in different countries was conducted in accordance with the same rules, with the assistance of specially trained examiners. All students were offered the same incentives to participate. We additionally tested the sensitivity of the results to possible differences in student motivation.'

The Supertest showed that at the start of their studies, Russian students perform lower than Chinese students in mathematics and physics, but higher than students from India in mathematics. After two years of study, the gap between Russian and Chinese students narrows, while Indian students catch up with Russian students in mathematics.

One finding of the study that is cause for concern relates to engineering students' critical thinking skills. Initially, upon entering university, Russian engineering students outperform Indian students while performing lower than Chinese students. In terms of developing these skills over the course of their studies, students of all three countries perform lower than students in the United States. 'We found that, as the students progress in their studies, their critical thinking skills remain approximately the same in Russia and India, but significantly decrease in China. On the contrary, American students show improvement,' said Igor Chirikov. This is a serious problem, the researchers note, because technologies change rapidly, and in order to be able to master new ones, you need not only a firm grasp of the subject area, but, above all, skills of the 21st century.

Another unexpected result was the gradual decline of academic skills among engineering students in China. 'Students at Chinese universities have an extremely high level of skills upon enrollment, but over the course of their university studies this level decreases: this applies to physics, mathematics, and critical thinking. We observe this at both elite and large universities, albeit to different extents,' said Igor Chirikov. 'A possible explanation lies in the way undergraduate education is organized in China, where institutions put emphasis on lectures, and instructors are not as demanding as in Russia and India. As a result, students have less motivation to learn and are not held accountable for developing skills.'

The results of the Supertest provide insight into how graduates perform in the globally competitive market of future computer science and electronic engineering professionals. Each represented country is renowned for its engineering expertise, and it is the Chinese, American, Russian and Indian specialists who migrate to different countries that largely determine the technological progress around the world. The balance of power in this sphere of education can play a decisive role in who will win the technology race tomorrow.