Tomato's wild ancestor is a genomic reservoir for plant breeders

Humans turned a weedy plant with tiny fruit into the tomato that we know today. That wild ancestor could lead to tomatoes that taste better, are more nutritious and more resilient.

BOYCE THOMPSON INSTITUTE

Research News

 

IMAGE: THE FRUITS OF SOLANUM PIMPINELLIFOLIUM, THE WILD ANCESTOR OF MODERN CULTIVATED TOMATOES, ARE ABOUT THE SIZE OF BLUEBERRIES. view more 

CREDIT: SCOTT PEACOCK AND THE C.M. RICK TOMATO GENETICS RESOURCE CENTER.

ITHACA, NY, December 1, 2020 -- Thousands of years ago, people in South America began domesticating Solanum pimpinellifolium, a weedy plant with small, intensely flavored fruit. Over time, the plant evolved into S. lycopersicum - the modern cultivated tomato.

Although today's tomatoes are larger and easier to farm compared with their wild ancestor, they also are less resistant to disease and environmental stresses like drought and salty soil.

Researchers from Boyce Thompson Institute, led by Zhangjun Fei, created a high-quality reference genome for S. pimpinellifolium and discovered sections of the genome that underlie fruit flavor, size and ripening, stress tolerance and disease resistance. The results were published in Nature Communications on November 16.

"This reference genome will allow researchers and plant breeders to improve traits like fruit quality and stress tolerance in the tomato," said Fei, "for example, by helping them discover new genes in the modern tomato as well as by reintroducing genes from S. pimpinellifolium that were lost over time as S. lycopersicum was domesticated."

Fei is a BTI faculty member and co-corresponding author on the paper, as well as an adjunct professor in Cornell University's School of Integrative Plant Science (SIPS).

Although other groups had previously sequenced S. pimpinellifolium, Fei said this reference genome is more complete and accurate, thanks in part to cutting-edge sequencing technologies that are able to read very long pieces of DNA.

"Older sequencing technologies that read short pieces of DNA can identify mutations at the single-base level," said Shan Wu, a postdoctoral scientist in Fei's lab and co-corresponding author on the paper. "But they aren't good at finding structural variants, like insertions, deletions, inversions or duplications of large chunks of DNA."

"Many known traits of the tomato are caused by structural variants, so that is why we focused on them," Fei said. "Structural variants also are understudied because they are more difficult to identify."

Fei's group compared their S. pimpinellifolium reference genome to that of the cultivated tomato, called Heinz 1706, and found more than 92,000 structural variants.

The researchers then combed the tomato pan-genome, a database with the genomes of more than 725 cultivated and closely related wild tomatoes, and discovered structural variants related to many important traits. For example, the modern cultivated tomato has some genomic deletions that reduce their levels of lycopene, a red pigment with nutritional value, and an insertion that reduces their sucrose content.

Jim Giovannoni, BTI faculty member and co-author of the study, notes that many consumers are disappointed in the quality and flavor of modern production tomatoes because past breeding efforts ignored those traits in favor of performance and yield.

"Identification of the additional genetic diversity captured in the S. pimpinellifolium genome provides breeders with opportunities to bring some of these important features back to store-bought tomatoes," said Giovannoni, who is also an adjunct professor in SIPS and a scientist with the U.S. Department of Agriculture's Agricultural Research Service.

The researchers found many other structural variants that could be of interest to plant breeders, including variants in numerous disease-resistance genes and in genes involved in fruit size, ripening, hormonal regulation, metabolism, and the development of flowers, seeds and leaves.

The group also found structural variants associated with regulating the expression of genes involved in the biosynthesis of lipids in fruit skin, which could help improve the fruit's post-harvest performance.

"So much genetic diversity was lost during tomato domestication," Fei said. "These data could help bring some of that diversity back and result in tomatoes that taste better, are more nutritious and more resilient."

CAPTION

The fruits of Solanum pimpinellifolium, the wild ancestor of modern cultivated tomatoes, are about the size of blueberries.

CREDIT

Scott Peacock and the C.M. Rick Tomato Genetics Resource Center.

Other BTI faculty members who co-authored the paper include Carmen Catalá, who is also an adjunct assistant professor in SIPS, Gregory Martin, who is also a professor in SIPS, and Lukas Mueller, who is also an adjunct professor in SIPS. Susan Strickler, Director of the BTI Computational Biology Center (BCBC), also was a co-author.

The team sequenced the LA2093 accession of S. pimpinellifolium using plant material provided by the C.M. Rick Tomato Genetics Resource Center at the University of California, Davis.

About Boyce Thompson Institute:

Boyce Thompson Institute is a premier life sciences research institution located in Ithaca, New York. BTI scientists conduct investigations into fundamental plant and life sciences research with the goals of increasing food security, improving environmental sustainability in agriculture, and making basic discoveries that will enhance human health. Throughout this work, BTI is committed to inspiring and educating students and to providing advanced training for the next generation of scientists. BTI is an independent nonprofit research institute that is also affiliated with Cornell University. For more information, please visit BTIscience.org

Tweaking carotenoid genes helps 

tomatoes bring their a-game

A research team led by the University of Tsukuba shows that modern gene editing techniques can help tomato breeders introduce diversity and improve the nutrition and environmental impact of tomato crops

UNIVERSITY OF TSUKUBA

Research News

 

IMAGE: TOMATOES USED IN THE EXPERIMENT view more 

CREDIT: UNIVERSITY OF TSUKUBA

Tsukuba, Japan - Cooked, fresh, sun-dried, or juiced, whichever way you prefer them, tomatoes are arguably one of the most versatile fruits on the planet--and yes, despite mainly being used in savory dishes, tomatoes really are a fruit.

The popularity of tomatoes has led to the development of more than 10,000 cultivars of various sizes, shapes, and hues. Interestingly though, there is little genetic diversity among modern tomato varieties. This lack of diversity, coupled with the fact that many traits are controlled by multiple genes, makes improving plant yield and quality a major challenge for tomato breeders.

But in a study published this week in Scientific Reports, researchers led by the University of Tsukuba explain how modern gene editing technology may be able to give tomato breeders a helping hand.

"The tomato was the first genetically modified food to be approved for human consumption," says senior author of the study Professor Hiroshi Ezura. "However, many early transgenic varieties contained genes derived from other species, raising safety concerns among consumers. Therefore, coupled with the fact that most transgenic varieties showed only moderate improvements in quality, tomato breeding has, for the most part, moved away from transgenics."

Unlike traditional genetic modification, modern gene editing techniques leave no trace in the genome and can introduce small changes within a native gene, mimicking natural variation.

Tomatoes contain relatively high levels of carotenoids, the yellow, red, and orange pigments found in many plants. Carotenoids are precursors to vitamin A and demonstrate antioxidant and anti-cancer properties, making them hugely important to human nutrition. Several natural mutations that enhance carotenoid accumulation in tomatoes have been documented, but their introduction into commercial varieties is a complicated and time-consuming prospect.

The University of Tsukuba-led team therefore set about reproducing carotenoid accumulation mutations in tomatoes using gene editing technology.

"Single nucleotide changes in individual tomato genes had previously been achieved using Target-AID gene editing technology," explains Professor Ezura. "However, we designed a system whereby changes were simultaneously introduced into three genes associated with carotenoid accumulation."

Among 12 resulting tomato lines, 10 contained mutations in all three target genes. Further examination of two lines with the dark green fruit and purple roots of natural carotenoid accumulation mutants revealed high levels of carotenoids, particularly lycopene, in the gene-edited plants.

Professor Ezura explains, "This shows that it is possible to improve multigenic plant quality traits using gene editing technology, and opens up a whole range of options for improving the yield, shelf-life, nutrient content, and disease resistance of different crop plants, which has obvious benefits for both human health and the environment."

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Bleach-alternative COVID-19 surface disinfectants may pollute indoor air: USask research

UNIVERSITY OF SASKATCHEWAN

Research News

 

IMAGE: LEFT TO RIGHT, YORK UNIVERSITY CHEMISTRY RESEARCHER CORA YOUNG, USASK CANADA RESEARCH CHAIR TARA KAHAN, SYRACUSE UNIVERSITY POST-DOCTORAL FELLOW SHAN ZHOU MEASURE AIR QUALITY IN A SIMULATED ROOM IN A... view more 

CREDIT: TREVOR VANDENBOER

Cleaning surfaces with hydrogen peroxide-based disinfectants has the potential to pollute the air and pose a health risk, according to research led by University of Saskatchewan (USask).

The research team found that mopping a floor with a commercially available hydrogen peroxide-based disinfectant raised the level of airborne hydrogen peroxide to more than 600 parts per billion--about 60 per cent of the maximum level permitted for exposure over eight hours, and 600 times the level naturally occurring in the air. The results were just published in the journal Environmental Science & Technology.

"When you're washing surfaces, you are also changing the air you are breathing," said USask chemistry researcher Tara Kahan, senior author of the study and Canada Research Chair in Environmental Analytical Chemistry. "Poor indoor air quality is associated with respiratory issues such as asthma."

Too much exposure to hydrogen peroxide could lead to respiratory, skin, and eye irritation, according to the U.S. Centres for Disease Control.

The COVID-19 pandemic has led to increased cleaning and demand for all types of cleaning products, including bleach alternatives that contain hydrogen peroxide.

"At the beginning of the pandemic, we couldn't do research on this topic because hydrogen peroxide solutions were out of stock," Kahan said.

Kahan's team, which also included researchers from Syracuse University, York University (Toronto), and University of York (England), sprayed the vinyl floor in a simulated room environment with 0.88 per cent hydrogen peroxide disinfectant and wiped it dry with paper towel either immediately or after letting it soak in for an hour. The team then tested the air at human head height.

"The real risk is for people who get repeatedly exposed, such as janitors and house cleaners," Kahan said. "We washed the floor and collected measurements at face height--the concentrations will be even stronger at the floor or at the level of a countertop."

Kahan said that the impact on children and pets--those physically closer to the disinfected surfaces--is not yet known.

More than 10 per cent of disinfectants approved by Health Canada that are deemed likely to be effective against SARS-CoV-2 use hydrogen peroxide as the active ingredient. A total of 168 disinfecting products containing hydrogen peroxide as the active ingredient are approved or marketed in Canada.

There are a few ways to reduce risks while disinfecting your home, Kahan says:

• Consider using soap and water instead of a disinfectant--soap and water are known to kill the virus that causes COVID-19.
• Consider opening a window, turning on a range hood, or using your central air system--ventilation can dramatically reduce levels of pollutants circulating in the air and is one of the most effective methods of removing particles that can carry the virus.
• Opt for hydrogen peroxide-based disinfectants over bleach, as Kahan notes "Hydrogen peroxide is still much less potentially harmful than bleach."

Funded by the Canada Research Chairs program and the Alfred P. Sloan Foundation, Kahan's team--mostly women in a discipline which tends to be male-dominated--is currently repeating the experiment in a house and apartment in Saskatoon to determine whether the high numbers occur in a real world environment and to find practical ways to mitigate exposure risks.

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Forearm fractures may signal intimate partner violence

RADIOLOGICAL SOCIETY OF NORTH AMERICA

Research News

 

IMAGE: X-RAY SHOWS FRACTURE TO THE ULNA BONE OF THE FOREARM. view more 

CREDIT: RADIOLOGICAL SOCIETY OF NORTH AMERICA

OAK BROOK, Ill. - Up to one-third of adult women who sustain a non-displaced fracture to the ulna bone of the forearm may be victims of intimate partner violence, according to a study being presented at the annual meeting of the Radiological Society of North America (RSNA). The findings underscore the need to screen for intimate partner violence in women with these types of injuries, researchers said.

Fractures to the ulna, the bone on the pinkie side of the forearm, often occur when people hold up their hands to protect their faces from being struck with an object. These breaks are referred to as "nightstick fractures," because they are frequently seen in people who try to block blows from nightsticks wielded by police officers.

Bharti Khurana, M.D., a radiologist at Brigham and Women's Hospital in Boston and senior author of the study, had observed these fractures in her practice for years, mostly in men. But it was the occasional woman she saw that raised questions.

"I would see these types of injuries in men, but once in a while I would see them in women," Dr. Khurana said. "I never correlated it with intimate partner violence until recently. I shared my thoughts with our orthopedic surgeons and, with their interest and support, decided to pursue the study."

For the study, Dr. Khurana and colleagues searched electronic medical records from six hospitals for isolated ulnar fractures in women ages 18 to 50. They identified 62 patients, average age 31. Of those, 12 were confirmed for intimate partner violence and another eight were suspected of intimate partner violence.

Analysis of the radiographs demonstrated that intimate partner violence was strongly associated with minimally displaced fractures.

"The radiological characteristics we were looking at were the location of the fracture, the pattern of the fracture in terms of how it broke, and the displacement of the fracture," said study lead author David Sing, M.D., an orthopedic surgery resident at Boston Medical Center. "Out of all those things, what we usually saw was a minimally displaced fracture, meaning the bone is broken all the way through but has not shifted significantly."

Confirmed cases were also linked with homelessness and previous visits to the emergency department with musculoskeletal injuries.

Women with ulnar fractures from intimate partner violence who are reluctant to report the crime will often attribute their injuries to a fall, Dr. Khurana said. However, she noted, falls are much more likely to result in a fracture of the radius, the other bone of the forearm.

This observation was supported by the study, as all the patients who were not victims of intimate partner violence had ulnar fractures from motor vehicle accidents or accidental striking, such as from crashing into a tree while skiing. Of the eight patients where intimate partner violence was suspected, four reported a fall.

"It's actually rare to break your ulna in a fall," Dr. Khurana said. "If a radiologist is seeing an ulnar fracture that is non-displaced, and the woman says she had a fall, it's actually quite concerning for intimate partner violence."

The study results suggest that intimate partner violence screening may be underutilized. Formal documentation of intimate partner violence evaluation or screening was completed in only 40% of confirmed/suspected intimate partner violence cases in the study. According to the researchers, radiologists who observe non-displaced ulnar fractures can help close that shortfall by letting the emergency department physician or orthopedic surgeon know that the fracture is often seen in intimate partner violence. The ordering physician can then look at the patient's clinical history to see if there is anything suspicious.

"Careful analysis of previous imaging exams may also help radiologists confirm their suspicion of intimate partner violence," said study co-author Rahul Gujrathi, M.D., a radiology fellow at Brigham and Women's Hospital.

In the study, for instance, historical imaging analysis alone was able to raise suspicion in 75% of clinically confirmed intimate partner violence patients.

"We have resources that we can provide to the patients who are stuck in that situation," Dr. Sing said. "It's especially important during COVID-19, where we've seen the rate of intimate partner violence go up with people trapped at home with their abusers."

Dr. Khurana, who devotes much of her research to identifying radiological signs of intimate partner violence, believes that a more widespread awareness of the association between ulnar fractures and intimate partner violence will help provide earlier detection and intervention.

"The sooner we can address and change the behavior, the better," she said. "Just like radiologists want to diagnose cancer as early as possible, it's the same thing with this. If we diagnose early, we have a better chance to break the cycle of violence."

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This research was partially funded by a Gillian Reny Stepping Strong Innovator Award, Brigham Health. Co-authors are George Dyer, M.D., Mitchel B. Harris, M.D., Camden Bay, Ph.D., Irene Chen, Steven E. Seltzer, M.D., Giles W. Boland M.D., and Paul Tornetta, III, M.D.

For more information and images, visit RSNA.org/press20. Press account required to view embargoed materials.

RSNA is an association of radiologists, radiation oncologists, medical physicists and related scientists promoting excellence in patient care and health care delivery through education, research and technologic innovation. The Society is based in Oak Brook, Illinois. (RSNA.org)

Editor's note: The data in these releases may differ from those in the published abstract and those actually presented at the meeting, as researchers continue to update their data right up until the meeting. To ensure you are using the most up-to-date information, please call the RSNA media relations team at Newsroom at 1-630-590-7762.

For patient-friendly information on emergency radiology, visit RadiologyInfo.org.

Forest fires, cars, power plants join list of risk factors for Alzheimer's disease

Airborne pollution implicated in amyloid plaques, UCSF-led study shows

UNIVERSITY OF CALIFORNIA - SAN FRANCISCO

Research News

 

A new study led by researchers at UC San Francisco has found that among older Americans with cognitive impairment, the greater the air pollution in their neighborhood, the higher the likelihood of amyloid plaques - a hallmark of Alzheimer's disease. The study adds to a body of evidence indicating that pollution from cars, factories, power plants and forest fires joins established dementia risk factors like smoking and diabetes.

In the study, which appears in JAMA Neurology on Nov.30, 2020, the researchers looked at the PET scans of more than 18,000 seniors whose average age was 75. The participants had dementia or mild cognitive impairment and lived in zip codes dotted throughout the nation. The researchers found that those in the most polluted areas had a 10 percent increased probability of a PET scan showing amyloid plaques, compared to those in the least polluted areas.

When applied to the U.S. population, with an estimated 5.8 million people over 65 with Alzheimer's disease, high exposure to microscopic airborne particles may be implicated in tens of thousands of cases.

"This study provides additional evidence to a growing and convergent literature, ranging from animal models to epidemiological studies, that suggests air pollution is a significant risk factor for Alzheimer's disease and dementia," said senior author Gil Rabinovici, MD, of the UCSF Memory and Aging Center, Department of Neurology and the Weill Institute for Neurosciences.

Amyloid Plaques Not Indicative of All Dementias

The 18,178 participants had been recruited for the IDEAS study (Imaging Dementia - Evidence for Amyloid Scanning), which had enrolled Medicare beneficiaries whose mild cognitive impairment or dementia had been diagnosed following comprehensive evaluation. Not all of the participants were later found to have positive PET scans - 40 percent showed no evidence of plaques on the scan, suggesting non-Alzheimer's diagnoses like frontotemporal or vascular dementias, which are not associated with the telltale amyloid plaques.

Air pollution in the neighborhood of each participant was estimated with Environmental Protection Agency data that measured ground-level ozone and PM2.5, atmospheric particulate matter that has a diameter of less than 2.5 micrometers. The researchers also divided locations into quartiles according to the concentration of PM2.5. They found that the probability of a positive PET scan rose progressively as concentrations of pollutants increased, and predicted a difference of 10 percent probability between the least and most polluted areas.

"Exposure in our daily lives to PM2.5, even at levels that would be considered normal, could contribute to induce a chronic inflammatory response," said first author Leonardo Iaccarino, PhD, also of the UCSF Memory and Aging Center, Department of Neurology and the Weill Institute of Neurosciences. "Over time, this could impact brain health in a number of ways, including contributing to an accumulation of amyloid plaques."

Overall concentrations of PM2.5 would not be considered very high for it to have a significant association with amyloid plaques, amounting to annual averages in San Francisco during the study time, added Rabinovici.

"I think it's very appropriate that air pollution has been added to the modifiable risk factors highlighted by the Lancet Commission on dementia," he said, referring to the journal's decision this year to include air pollution, together with excessive alcohol intake and traumatic brain injury, to their list of risk factors.

The study complements previous large-scale studies that tie air pollution to dementia and Parkinson's disease, and adds novel findings by including a cohort with mild cognitive impairment - a frequent precursor to dementia - and using amyloid plaques as a biomarker of disease. Other studies have linked air pollution to adverse effects on cognitive, behavioral and psychomotor development in children, including a UCSF-University of Washington study that looked at its impact on the IQ of the offspring of pregnant women.

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Co-Authors:
Renaud La Joie, PhD, Eunice Lee, PhD, and Isabel Allen, PhD, of UCSF; Orit Lesman-Segev, MD, of UCSF and Sheba Medical Center, Israel; Lucy Hanna and Constantine Gatsonis, PhD, of Brown University School of Public Health; Bruce Hillner, MD, of Virginia Commonwealth University; Barry Siegel, MD, of Washington University School of Medicine; Rachel Whitmer, PhD, of Kaiser Permanente, Oakland, and UC Davis; Maria Carrillo, PhD, of the Alzheimer's Association.

Funding:
The IDEAS study was funded by the Alzheimer's Association, the American College of Radiology, Avid Radiopharmaceuticals, Inc, GE Healthcare and Life Molecular Imaging.

Conflicts of Interest:
Disclosures are listed in the paper in JAMA Neurology.

About UCSF:
The University of California, San Francisco (UCSF) is exclusively focused on the health sciences and is dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. UCSF Health, which serves as UCSF's primary academic medical center, includes top-ranked specialty hospitals and other clinical programs, and has affiliations throughout the Bay Area. Learn more at ucsf.edu, or see our Fact Sheet.

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Astronomical instrument hunts for ancient metal

A new study looks at quasars to explore the origin of the iron in your blood

UNIVERSITY OF TOKYO

Research News

 

IMAGE: THE WINERED SPECTROGRAPH WAS MOUNTED ON THE 3.58-METER NEW TECHNOLOGY TELESCOPE (NTT) AT THE LA SILLA OBSERVATORY IN CHILE. view more 

CREDIT: © 2020 EUROPEAN SOUTHERN OBSERVATORY/B. TAFRESHI

Researchers created a new astronomical instrument that has successfully aided in estimating the abundance of metals in the early universe. The WINERED instrument allows for better observations of astronomical bodies like quasars in the early universe, billions of years ago. Researchers hope this deeper level of exploration could help answer questions about the origins not only of metals in the universe but also of the stars themselves.

Iron is one of the most important elements for life as we know it, and for the technology, both primitive and modern, that has shaped human history. But details of the exact origin of iron and other important metals such as magnesium remain elusive. Exploration of this is important in the field of astronomy as it also connected to the origins of the first stars that would have begun to shine several hundred million years after the Big Bang.

Project Research Associate Hiroaki Sameshima from the Institute of Astronomy at the University of Tokyo and his team decided a new instrument was needed to study these matters. Due to limited instrumentation, previous observations to collect data for the study of metals' origins mainly looked at old stars nearby. But this only gave astronomers information about our own unique galaxy. A new instrument with enhanced sensitivity to near-infrared light could push the boundary and open up observations of distant quasars, ferociously energetic ancient galactic cores that emitted light when the universe was only 2.4 billion years old.

"By mounting the WINERED instrument on a large telescope, we can see further back in time as we can observe bodies more distant, or more ancient, than those from previous studies. We can now see details of quasars over 10 billion years old," said Sameshima. "WINERED is a special kind of spectrograph, which can read the chemical signatures present in the light from distant bodies. It revealed to us the fingerprints of iron and magnesium in the light from these quasars, and this allowed us to calculate the abundance of these elements when the universe was much younger than previous studies allowed."

Now that the researchers have established a new method to directly examine the abundance of metals in the early universe, the challenge becomes one of refining the technique and broadening its scope to collect more data. With improved data, astronomers can build on this study and create theories to explain the origins of metals including the iron in your blood.

CAPTION

The WINERED instrument allows observations of distant quasars from when the universe was only 2.4 billion years old. Previous studies with visible light were limited to astronomical bodies 4 billion years old. The colored lines represent three different possible models for the chemical evolution of the universe.

CREDIT

© 2020 Sameshima et al.

Journal article

Hiroaki Sameshima, Yuzuru Yoshii, Noriyuki Matsunaga, Naoto Kobayashi, Yuji Ikeda, Sohei Kondo, Satoshi Hamano, Misaki Mizumoto, Akira Arai, Chikako Yasui, Kei Fukue, Hideyo Kawakita, Shogo Otsubo, Giuseppe Bono and Ivo Saviane. Mg II and Fe II Fluxes of Luminous Quasars at z ~ 2.7 and Evaluation of the Baldwin Effect in the Flux-to-abundance Conversion Method for Quasars. The Astrophysical Journal.

https://arxiv.org/abs/2010.10548

Funding

The Japan Society for the Promotion of Science KAKENHI (grant numbers: 19K0397, 16684001, 20340042, 21840052). The MEXT Supported Program for the Strategic Research Foundation at Private Universities (grant numbers: S081061, S1411028). Hayakawa Satio Funds in the Astronomical Society of Japan.

Useful links

Institute of Astronomy - http://www.ioa.s.u-tokyo.ac.jp/
La Silla Observatory - https://www.eso.org/public/teles-instr/lasilla/
Graduate School of Science - https://www.s.u-tokyo.ac.jp/en/

Research contact

Hiroaki Sameshima
Institute of Astronomy, Graduate School of Science, The University of Tokyo,
2-21-1 Osawa, Mitaka, Tokyo 181-0015, JAPAN
Tel: +81(0)-422-34-5021
Email: hsameshima@ioa.s.u-tokyo.ac.jp

Press Contact

Mr. Rohan Mehra
Division for Strategic Public Relations, The University of Tokyo
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, JAPAN
Email: press-releases.adm@gs.mail.u-tokyo.ac.jp

About the University of Tokyo

The University of Tokyo is Japan's leading university and one of the world's top research universities. The vast research output of some 6,000 researchers is published in the world's top journals across the arts and sciences. Our vibrant student body of around 15,000 undergraduate and 15,000 graduate students includes over 4,000 international students. Find out more at http://www.u-tokyo.ac.jp/en/ or follow us on Twitter at @UTokyo_News_en.

FASTER PUSSY CAT, KILL, KILL, KILL

Earth faster, closer to black hole in new map of galaxy

NATIONAL INSTITUTES OF NATURAL SCIENCES

Research News

 

IMAGE: ARROWS SHOW POSITION AND VELOCITY DATA FOR THE 224 OBJECTS USED TO MODEL THE MILKY WAY GALAXY. THE SOLID BLACK LINES SHOW THE POSITIONS OF THE GALAXY'S SPIRAL ARMS. THE... view more 

CREDIT: NAOJ

Earth just got 7 km/s faster and about 2000 light-years closer to the supermassive black hole in the center of the Milky Way Galaxy. But don't worry, this doesn't mean that our planet is plunging towards the black hole. Instead the changes are results of a better model of the Milky Way Galaxy based on new observation data, including a catalog of objects observed over the course of more than 15 years by the Japanese radio astronomy project VERA.

VERA (VLBI Exploration of Radio Astrometry, by the way "VLBI" stands for Very Long Baseline Interferometry) started in 2000 to map three-dimensional velocity and spatial structures in the Milky Way. VERA uses a technique known as interferometry to combine data from radio telescopes scattered across the Japanese archipelago in order to achieve the same resolution as a 2300 km diameter telescope would have. Measurement accuracy achieved with this resolution, 10 micro-arcseconds, is sharp enough in theory to resolve a United States penny placed on the surface of the Moon.

Because Earth is located inside the Milky Way Galaxy, we can't step back and see what the Galaxy looks like from the outside. Astrometry, accurate measurement of the positions and motions of objects, is a vital tool to understand the overall structure of the Galaxy and our place in it. This year, the First VERA Astrometry Catalog was published containing data for 99 objects.

Based on the VERA Astrometry Catalog and recent observations by other groups, astronomers constructed a position and velocity map. From this map they calculated the center of the Galaxy, the point that everything revolves around. The map suggests that the center of the Galaxy, and the supermassive black hole which resides there, is located 25800 light-years from Earth. This is closer than the official value of 27700 light-years adopted by the International Astronomical Union in 1985. The velocity component of the map indicates that Earth is travelling at 227 km/s as it orbits around the Galactic Center. This is faster than the official value of 220 km/s.

Now VERA hopes to observe more objects, particularly ones close to the central supermassive black hole, to better characterizes the structure and motion of the Galaxy. As part of these efforts VERA will participate in EAVN (East Asian VLBI Network) comprised of radio telescope located in Japan, South Korea, and China. By increasing the number of telescopes and the maximum separation between telescopes, EAVN can achieve even higher accuracy.

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"The First VERA Astrometry Catalog" by VERA collaboration et al. appeared in Publications of the Astronomical Society of Japan in August 2020.

 

Mystery of Siberian freshwater seal food choice solved

RESEARCH ORGANIZATION OF INFORMATION AND SYSTEMS

Research News

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IMAGE: SKULL AND JAW DEMONSTRATING THE HIGHLY SPECIALIZED, COMB-LIKE TEETH OF THE BAIKAL SEAL THAT ALLOW THEM TO EXPEL WATER WHILE RETAINING PREY DURING HIGH-SPEED HUNTING. THIS TOGETHER WITH THEIR SMALL... view more 

CREDIT: NIPR

Through video tracking and examination of museum specimens, scientists have discovered why Siberia's Lake Baikal seals are thriving when so many other seal populations are suffering from human-caused environmental stresses.

Lake Baikal is the largest and deepest freshwater lake in the world, containing more water than all of North America's Great Lakes combined. Native only to the lake whose name it bears, the Baikal seal is the only exclusively freshwater seal in the world.

Baikal seals are thriving in this location even as populations of many seals elsewhere have been hit by anthropogenic stresses. It appears to quite like chomping on amphipods, extremely tiny crustaceans typically under 10mm long. These are so small that in terms of the energy gained from eating them, it really should not be worth the hassle of hunting them individually. Yet Lake Baikal seals do precisely this, a rare behaviour for seals or toothed whales anywhere else.

It turns out they have highly specialized comb-line teeth that allow them to expel water while retaining prey during high-speed hunting. Their small size, compared to most other seals, also allows them to achieve a net energy gain from these crustaceans that no other aquatic mammals are terribly keen to eat, according to a study published November 16, 2020 in Proceedings of the National Academy of Sciences (PNAS).

While researchers until now had thought Baikal seals primarily stuck to fish, past investigations of stomach contents have shown that Lake Baikal seals also feed on the amphipod Macrohectopus branickii, the world's only freshwater amphipod with a planktonic (floating) lifestyle. But the plankton's tiny size (only a few centimeters long and weighing less than 0.1gram) and the fact that all of its body parts are digestible made it challenging to ascertain just how much plankton these seals ate - and how such tiny prey sustains the seal.

Using animal-borne accelerometers and video cameras, Yuuki Watanabe, a marine biologist with Japan's National Institute of Polar Research, and colleagues recorded Baikal seals' foraging behavior, and found that contrary to the prevailing view that they mainly eat fish, the seals actually hunted the amphipod at extremely high rates.

On average, Baikal seals caught 57 amphipods per dive - not all at once, but hunting them individually, leading to thousands of amphipod catches per day. This represents the highest consumption rate ever recorded of any aquatic mammal that feeds on single prey one at a time rather than scooping up lots of different types of prey all at once. In one case, the research team observed a seal hunting down 154 individual amphipods, meaning that it hunted one every 2.5 seconds.

Everywhere else in the world, amphipods are rarely targeted by aquatic mammals, except for a few baleen whales which are able to do so using baleen, which acts as a great big filter to collect krill, plankton and small fish. But hunting these tiny crustaceans individually would have made gaining an energy surplus almost impossible. Swallowing prey and water together requires extra muscular activity, adding to the energy expenditure, and in turn slowing down foraging rates, further reducing the energy profit.

"Each time the seals open their mouth to try to catch an amphipod, there is this huge drawback," said Watanabe, the paper's first author. "Water is inevitably going to be swallowed too."

To answer this question, the team examined museum specimens of the seal, and found that Baikal seals have the most specialized comb-like post-canine teeth in the subfamily Phocinae (Northern seals). This unique feature allows them to expel water while retaining prey during high-speed foraging.

The small body size of the Baikal seals also plays a role in making individual hunting of tiny amphipods energetically rational. Weighing in at around 50 kilograms, they are some of the smallest seals in the world. The researchers modeled the relationship of predator body size, prey body size, and the number of prey a predator needs to consume per dive to replenish the energy expended during the dive. As predator body mass increases, the number of prey needed to be caught per dive increases rapidly. But the Baikal seal size hits the sweet spot where there is a substantial energy profit.

The final piece of the puzzle of the Baikal seal's unique prey choice, and why it hasn't been threatened by human-caused environmental changes lies in where it lives: Lake Baikal produces very little algae but is abundant in amphipods.

"This apparent paradox can at least partly be resolved by our finding that the seals eat the amphipods instead of just eating the fish that eat the amphipods," said Watanabe.

When an organism from a lower trophic level, or food chain, is consumed by one at a higher level, there is a certain loss of energy. "When the seals eat the prey of the fish directly, they are basically shortcutting this chain, and thus avoiding that energy loss."

The researchers conclude that this evolutionary innovation gives the ecosystem a greater capacity to support apex predators than would otherwise be the case, even given significant levels of human disturbance.

CAPTION

A Baikal seal

About National Institute of Polar Research (NIPR)

The NIPR engages in comprehensive research via observation stations in Arctic and Antarctica. As a member of the Research Organization of Information and Systems (ROIS), the NIPR provides researchers throughout Japan with infrastructure support for Arctic and Antarctic observations, plans and implements Japan's Antarctic observation projects, and conducts Arctic researches of various scientific fields such as the atmosphere, ice sheets, the ecosystem, the upper atmosphere, the aurora and the Earth's magnetic field. In addition to the research projects, the NIPR also organizes the Japanese Antarctic Research Expedition and manages samples and data obtained during such expeditions and projects. As a core institution in researches of the polar regions, the NIPR also offers graduate students with a global perspective on originality through its doctoral program. For more information about the NIPR, please visit: https://http://www.nipr.ac.jp/english/

About the Research Organization of Information and Systems (ROIS)

The Research Organization of Information and Systems (ROIS) is a parent organization of four national institutes (National Institute of Polar Research, National Institute of Informatics, the Institute of Statistical Mathematics and National Institute of Genetics) and the Joint Support-Center for Data Science Research. It is ROIS's mission to promote integrated, cutting-edge research that goes beyond the barriers of these institutions, in addition to facilitating their research activities, as members of inter-university research institutes.