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Penguin hemoglobin evolved to meet oxygen demands of diving: Experiments on ancient proteins reveal evolution of better oxygen capture, release

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Penguin hemoglobin evolved to meet oxygen demands of diving: Experiments on ancient proteins reveal evolution of better oxygen capture, release

Call it the evolutionary march of the penguins.

More than 50 million years ago, the lovable tuxedoed birds began leaving their avian relatives at the shoreline by waddling to the water’s edge and taking a dive in the pursuit of seafood.Webbed feet, flipper-like wings and unique feathers all helped penguins adapt to their underwater excursions. But new research from the University of Nebraska-Lincoln has shown that the evolution of diving is also in their blood, which optimized its capture and release of oxygen to ensure that penguins wouldn’t waste their breath while holding it.

Relative to land-dwelling birds, penguin blood is known to contain more hemoglobin: the protein that picks up oxygen from the lungs and transports it through the bloodstream before dropping it off at various tissues. That abundance could partly explain the underwater proficiency of, say, the emperor penguin, which dives deeper than any bird and has been documented holding its breath for more than 30 minutes while preying on krill, fish and squid.

Still, the particulars of their hemoglobin — and how much it actually evolved to help penguins become fish-gobbling torpedoes that spend up to half of their lives underwater — remained open questions. So Nebraska biologists Jay Storz and Anthony Signore, who often study the hemoglobin of birds that survive miles above sea level, decided to investigate the birds most adept at diving beneath it.

“There just wasn’t a lot of comparative work on blood-oxygen transport as it relates to diving physiology in penguins and their non-diving relatives,” said Signore, a postdoctoral researcher in Storz’s lab.Answering those questions meant sketching in the genetic blueprints of two ancient hemoglobins. One belonged to the common ancestor of all penguin species, which began branching from that ancestor about 20 million years ago. The other, dating back roughly 60 million years, resided in the common ancestor of penguins and their closest non-diving relatives — albatrosses, shearwaters and other flying seabirds. The thinking was simple: Because one hemoglobin originated before the emergence of diving in the lineage, and the other after, any major differences between the two would implicate them as important to the evolution of diving in penguins.

Actually comparing the two was less simple. To start, the researchers literally resurrected both proteins by relying on models that factored in the gene sequences of modern hemoglobins to estimate the sequences of their two ancient counterparts. Signore spliced those resulting sequences into E. coli bacteria, which churned out the two ancient proteins. The researchers then ran experiments to evaluate the performance of each.

They found that the hemoglobin from the common ancestor of penguins captured oxygen more readily than did the version present in the blood of the older, non-diving ancestor. That stronger affinity for oxygen would mean less chance of leaving behind traces in the lungs, an especially vital issue among semi-aquatic birds needing to make the most of a single breath while hunting or traveling underwater.

Unfortunately, the very strength of that affinity can present difficulties when hemoglobin arrives at tissues starved for the oxygen it’s carrying.

“Having a greater hemoglobin-oxygen affinity sort of acts like a stronger magnet to pull more oxygen from the lungs,” Signore said. “It’s great in that context. But then you’re at a loss when it’s time to let go.”

Any breath-holding benefits gained by picking up extra oxygen, in other words, can be undone if the hemoglobin struggles to relax its iron-clad grip and release its prized cargo. The probability that it will is dictated in part by acidity and carbon dioxide in the blood. Higher levels of either make hemoglobins more likely to loosen upAs Storz and Signore expected, the hemoglobin of the recent penguin ancestor was more sensitive to its surrounding pH, with its biochemical grip on oxygen loosening more in response to elevated acidity. And that, Signore said, made the hemoglobin more biochemically attuned to the exertion and oxygen needs of the tissues it served.

“It really is a beautiful system, because tissues that are working hard are becoming acidic,” he said. “They need more oxygen, and hemoglobin’s oxygen affinity is able to shift in response to that acidity to provide more oxygen.

“If pH drops by, say, 0.2 units, the oxygen affinity of penguin hemoglobin is going to decrease by more than would the hemoglobin of their non-diving relatives.”

Together, the findings indicate that as penguins took to the seas, their hemoglobin evolved to maximize both the pick-up and drop-off of available oxygen — especially when it was last inhaled five, or 10, or even 20 minutes earlier. They also illustrate the value of resurrecting proteins that last existed 20, or 40, or even 60 million years ago.

“”These results demonstrate how the experimental analysis of ancestral proteins can reveal the mechanisms of biochemical adaptation,” Storz said, “and also shed light on how organismal physiology evolved in response to new environmental challenges.””

The researchers received support from the National Institutes of Health and the National Science Foundation.

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Inherited predisposition for higher muscle strength may protect against common morbidities

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Penguin hemoglobin evolved to meet oxygen demands of diving: Experiments on ancient proteins reveal evolution of better oxygen capture, release


A study conducted at the Faculty of Sport and Health Sciences at the University of Jyväskylä showed that a genetic predisposition for higher muscle strength predicts a longer lifespan and a lower risk for developing common diseases. This is the most comprehensive international study to date on hereditary muscle strength and its relationship to morbidity. The genome and health data of more than 340,000 Finns was used in the research.

Muscle strength, especially hand grip strength, can indicate an individual’s physiological resources to protect against age-related diseases and disabilities, as well as their ability to cope with them. Age-related loss of muscle strength is individual and influenced not only by lifestyle but also by genetics.

The study revealed that individuals with a genetic predisposition for higher muscle strength have a slightly lower risk for common noncommunicable diseases and premature mortality. However, it did not predict better survival after acute adverse health events compared to the time before illness onset.

“It seems that a genetic predisposition for higher muscle strength reflects more on an individual’s intrinsic ability to resist and protect oneself against pathological changes that occur during aging than the ability to recover or completely bounce back after severe adversity,” says doctoral researcher Päivi Herranen from the Faculty of Sport and Health Sciences.

The research utilized a unique study population

Muscle strength is a multifactorial trait influenced by lifestyle and environmental factors but also by numerous genetic variants, each with a very small effect on muscle strength. In this study, the genetic predisposition for muscle strength was defined by constructing a polygenic score for muscle strength, which summarizes the effects of hundreds of thousands of genetic variants into a single score. The polygenic score makes it possible to compare participants with an exceptionally high or low genetic predisposition for muscle strength, and to investigate associations with inherited muscle strength and other phenotypes, in this case, common diseases.

“In this study, we were able to utilize both genetic information and health outcomes from over 340,000 Finnish men and women,” Herranen explains.

“To our knowledge, this is the first study to investigate the association between a genetic predisposition for muscle strength and various diseases on this scale.”

Further research on the effects of lifestyles is still needed

Information about the genetic predisposition for muscle strength could be used alongside traditional risk assessment in identifying individuals who are at particularly high risk of common diseases and health adversities. However, further research on the topic is still needed.

“Based on these results, we cannot say how lifestyle factors, such as physical activity, modify an individual’s intrinsic ability to resist diseases and whether their impact on health differs among individuals due to genetics,” Herranen notes.

The study utilized the internationally unique FinnGen dataset, compiled through the collaboration of Finnish biobanks. The dataset consisted of 342,443 Finns who had given their consent and provided a biobank sample. The participants were aged 40 to 108 years, and 53% of them were women. The diagnoses selected for the study were based on the leading causes of death and the most significant noncommunicable diseases in Finland. Selected diagnoses included the most common cardiometabolic and pulmonary diseases, musculoskeletal and connective tissue diseases, falls and fractures, mental health and cognitive disorders, cancers, as well as overall mortality and mortality from cardiovascular diseases.

The study is the second publication of Päivi Herranen’s doctoral thesis, which investigates how genetics and environmental factors affect biological aging, particularly the weakening of muscle strength and functional capacity with age. The research is part of the GenActive project, funded by the Research Council of Finland and the Juho Vainio and Päivikki and Sakari Sohlberg foundations. The project is led by Assistant Professor and Academy Research Fellow Elina Sillanpää. The research was conducted in collaboration with the Gerontology Research Center (GEREC), the Institute for Molecular Medicine Finland (FIMM), and the FinnGen research project.



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Brightest gamma-ray burst of all time came from the collapse of a massive star

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Penguin hemoglobin evolved to meet oxygen demands of diving: Experiments on ancient proteins reveal evolution of better oxygen capture, release


In October 2022, an international team of researchers, including Northwestern University astrophysicists, observed the brightest gamma-ray burst (GRB) ever recorded, GRB 221009A.

Now, a Northwestern-led team has confirmed that the phenomenon responsible for the historic burst — dubbed the B.O.A.T. (“brightest of all time”) — is the collapse and subsequent explosion of a massive star. The team discovered the explosion, or supernova, using NASA’s James Webb Space Telescope (JWST).

While this discovery solves one mystery, another mystery deepens.

The researchers speculated that evidence of heavy elements, such as platinum and gold, might reside within the newly uncovered supernova. The extensive search, however, did not find the signature that accompanies such elements. The origin of heavy elements in the universe continues to remain as one of astronomy’s biggest open questions.

The research will be published on Friday (April 12) in the journal Nature Astronomy.

“When we confirmed that the GRB was generated by the collapse of a massive star, that gave us the opportunity to test a hypothesis for how some of the heaviest elements in the universe are formed,” said Northwestern’s Peter Blanchard, who led the study. “We did not see signatures of these heavy elements, suggesting that extremely energetic GRBs like the B.O.A.T. do not produce these elements. That doesn’t mean that all GRBs do not produce them, but it’s a key piece of information as we continue to understand where these heavy elements come from. Future observations with JWST will determine if the B.O.A.T.’s ‘normal’ cousins produce these elements.”

Blanchard is a postdoctoral fellow at Northwestern’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), where he studies superluminous supernovae and GRBs. The study includes co-authors from the Center for Astrophysics | Harvard & Smithsonian; University of Utah; Penn State; University of California, Berkeley; Radbound University in the Netherlands; Space Telescope Science Institute; University of Arizona/Steward Observatory; University of California, Santa Barbara; Columbia University; Flatiron Institute; University of Greifswald and the University of Guelph.

Birth of the B.O.A.T.

When its light washed over Earth on Oct. 9, 2022, the B.O.A.T. was so bright that it saturated most of the world’s gamma-ray detectors. The powerful explosion occurred approximately 2.4 billion light-years away from Earth, in the direction of the constellation Sagitta and lasted a few hundred seconds in duration. As astronomers scrambled to observe the origin of this incredibly bright phenomenon, they were immediately hit with a sense of awe.

“As long as we have been able to detect GRBs, there is no question that this GRB is the brightest we have ever witnessed by a factor of 10 or more,” Wen-fai Fong, an associate professor of physics and astronomy at Northwestern’s Weinberg College of Arts and Sciences and member of CIERA, said at the time.

“The event produced some of the highest-energy photons ever recorded by satellites designed to detect gamma rays,” Blanchard said. “This was an event that Earth sees only once every 10,000 years. We are fortunate to live in a time when we have the technology to detect these bursts happening across the universe. It’s so exciting to observe such a rare astronomical phenomenon as the B.O.A.T. and work to understand the physics behind this exceptional event.”

A ‘normal’ supernova

Rather than observe the event immediately, Blanchard, his close collaborator Ashley Villar of Harvard University and their team wanted to view the GRB during its later phases. About six months after the GRB was initially detected, Blanchard used the JWST to examine its aftermath.

“The GRB was so bright that it obscured any potential supernova signature in the first weeks and months after the burst,” Blanchard said. “At these times, the so-called afterglow of the GRB was like the headlights of a car coming straight at you, preventing you from seeing the car itself. So, we had to wait for it to fade significantly to give us a chance of seeing the supernova.”

Blanchard used the JWST’s Near Infrared Spectrograph to observe the object’s light at infrared wavelengths. That’s when he saw the characteristic signature of elements like calcium and oxygen typically found within a supernova. Surprisingly, it wasn’t exceptionally bright — like the incredibly bright GRB that it accompanied.

“It’s not any brighter than previous supernovae,” Blanchard said. “It looks fairly normal in the context of other supernovae associated with less energetic GRBs. You might expect that the same collapsing star producing a very energetic and bright GRB would also produce a very energetic and bright supernova. But it turns out that’s not the case. We have this extremely luminous GRB, but a normal supernova.”

Missing: Heavy elements

After confirming — for the first time — the presence of the supernova, Blanchard and his collaborators then searched for evidence of heavy elements within it. Currently, astrophysicists have an incomplete picture of all the mechanisms in the universe that can produce elements heavier than iron.

The primary mechanism for producing heavy elements, the rapid neutron capture process, requires a high concentration of neutrons. So far, astrophysicists have only confirmed the production of heavy elements via this process in the merger of two neutron stars, a collision detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2017. But scientists say there must be other ways to produce these elusive materials. There are simply too many heavy elements in the universe and too few neutron-star mergers.

“There is likely another source,” Blanchard said. “It takes a very long time for binary neutron stars to merge. Two stars in a binary system first have to explode to leave behind neutron stars. Then, it can take billions and billions of years for the two neutron stars to slowly get closer and closer and finally merge. But observations of very old stars indicate that parts of the universe were enriched with heavy metals before most binary neutron stars would have had time to merge. That’s pointing us to an alternative channel.”

Astrophysicists have hypothesized that heavy elements also might be produced by the collapse of a rapidly spinning, massive star — the exact type of star that generated the B.O.A.T. Using the infrared spectrum obtained by the JWST, Blanchard studied the inner layers of the supernova, where the heavy elements should be formed.

“The exploded material of the star is opaque at early times, so you can only see the outer layers,” Blanchard said. “But once it expands and cools, it becomes transparent. Then you can see the photons coming from the inner layer of the supernova.”

“Moreover, different elements absorb and emit photons at different wavelengths, depending on their atomic structure, giving each element a unique spectral signature,” Blanchard explained. “Therefore, looking at an object’s spectrum can tell us what elements are present. Upon examining the B.O.A.T.’s spectrum, we did not see any signature of heavy elements, suggesting extreme events like GRB 221009A are not primary sources. This is crucial information as we continue to try to pin down where the heaviest elements are formed.”

Why so bright?

To tease apart the light of the supernova from that of the bright afterglow that came before it, the researchers paired the JWST data with observations from the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile.

“Even several months after the burst was discovered, the afterglow was bright enough to contribute a lot of light in the JWST spectra,” said Tanmoy Laskar, an assistant professor of physics and astronomy at the University of Utah and a co-author on the study. “Combining data from the two telescopes helped us measure exactly how bright the afterglow was at the time of our JWST observations and allow us to carefully extract the spectrum of the supernova.”

Although astrophysicists have yet to uncover how a “normal” supernova and a record-breaking GRB were produced by the same collapsed star, Laskar said it might be related to the shape and structure of the relativistic jets. When rapidly spinning, massive stars collapse into black holes, they produce jets of material that launch at rates close to the speed of light. If these jets are narrow, they produce a more focused — and brighter — beam of light.

“It’s like focusing a flashlight’s beam into a narrow column, as opposed to a broad beam that washes across a whole wall,” Laskar said. “In fact, this was one of the narrowest jets seen for a gamma-ray burst so far, which gives us a hint as to why the afterglow appeared as bright as it did. There may be other factors responsible as well, a question that researchers will be studying for years to come.”

Additional clues also may come from future studies of the galaxy in which the B.O.A.T. occurred. “In addition to a spectrum of the B.O.A.T. itself, we also obtained a spectrum of its ‘host’ galaxy,” Blanchard said. “The spectrum shows signs of intense star formation, hinting that the birth environment of the original star may be different than previous events.”

Team member Yijia Li, a graduate student at Penn State, modeled the spectrum of the galaxy, finding that the B.O.A.T.’s host galaxy has the lowest metallicity, a measure of the abundance of elements heavier than hydrogen and helium, of all previous GRB host galaxies. “This is another unique aspect of the B.O.A.T. that may help explain its properties,” Li said.

The study, “JWST detection of a supernova associated with GRB 221009A without an r-process signature,” was supported by NASA (award number JWST-GO-2784) and the National Science Foundation (award numbers AST-2108676 and AST-2002577). This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope.



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Stellar winds of three sun-like stars detected for the first time

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Penguin hemoglobin evolved to meet oxygen demands of diving: Experiments on ancient proteins reveal evolution of better oxygen capture, release


An international research team led by a researcher from the University of Vienna has for the first time directly detected stellar winds from three Sun-like stars by recording the X-ray emission from their astrospheres, and placed constraints on the mass loss rate of the stars via their stellar winds. The study is currently published in Nature Astronomy.

Astrospheres, stellar analogues of the heliosphere that surrounds our solar system, are very hot plasma bubbles blown by stellar winds into the interstellar medium, a space filled with gas and dust. The study of the stellar winds of low-mass stars similar to the Sun allows us to understand stellar and planetary evolution, and ultimately the history and future of our own star and solar system. Stellar winds drive many processes that evaporate planetary atmospheres into space and therefore lead to atmospheric mass loss.

Although escape rates of planets over an hour or even a year are tiny, they operate over long geological periods. The losses accumulate and can be a decisive factor for a planet evolving into a habitable world or an airless rock. Despite their importance for the evolution of both stars and planets, winds of Sun-like stars are notoriously difficult to constrain. Mainly composed of protons and electrons, they also contain a small quantity of heavier highly charged ions (e.g. oxygen, carbon). It is these ions which, by capturing electrons from the neutrals of the interstellar medium around the star, emit X-rays.

X-ray emission from astropheres detected

An international research team led by Kristina Kislyakova, Senior Scientist at the Department of Astrophysics of the University of Vienna, has detected for the first time the X-ray emission from the astrospheres around three sun-like stars, so called main sequence stars which are stars in the prime of their life, and has thus recorded such winds for the first time directly, allowing them to place constraints on the mass loss rate of the stars via their stellar winds.

These results, based on observations with the XMM-Newton space telescope, are currently published in Nature Astronomy. The researchers observed the spectral fingerprints (so-called spectral lines) of the oxygen ions with XMM-Newton and were able to determine the quantity of oxygen and ultimately the total mass of stellar wind emitted by the stars. For the three stars with detected astrospheres, named 70 Ophiuchi, epsilon Eridani, and 61 Cygni, the researchers estimated their mass loss rates to be 66.5±11.1, 15.6±4.4, and 9.6±4.1 times the solar mass loss rate, respectively. This means that the winds from these stars are much stronger than the solar wind, which might be explained by stronger magnetic activity of these stars.

“In the solar system, solar wind charge exchange emission has been observed from planets, comets, and the heliosphere and provides a natural laboratory to study the solar wind’s composition,” explains the lead author of the study, Kristina Kislyakova. “Observing this emission from distant stars is much more tricky due to the faintness of the signal. In addition to that, the distance to the stars makes it very difficult to disentangle the signal emitted by the astrosphere from the actual X-ray emission of the star itself, part of which is “spread” over the field-of-view of the telescope due to instrumental effects. We have developed a new algorithm to disentangle the stellar and the astrospheric contributions to the emission and detected charge exchange signals originating from stellar wind oxygen ions and the surrounding neutral interstellar medium of three main-sequence stars. This has been the first time X-ray charge exchange emission from astrospheres of such stars has been detected. Our estimated mass loss rates can be used as a benchmark for stellar wind models and expand our limited observational evidence for the winds of Sun-like stars.”

Co-author Manuel Güdel, also of the University of Vienna, adds, “there have been world-wide efforts over three decades to substantiate the presence of winds around Sun-like stars and measure their strengths, but so far only indirect evidence based on their secondary effects on the star or its environment alluded to the existence of such winds; our group previously tried to detect radio emission from the winds but could only place upper limits to the wind strengths while not detecting the winds themselves. Our new X-ray based results pave the way to finding and even imaging these winds directly and studying their interactions with surrounding planets.”

“In the future, this method of direct detection of stellar winds in X-rays will be facilitated thanks to future high resolution instruments, like the X-IFU spectrometer of the European Athena mission. The high spectral resolution of X-IFU will resolve the finer structure and emission ratio of the oxygen lines (as well as other fainter lines), that are hard to distinguish with XMM’s CCD resolution, and provide additional constraints on the emission mechanism; thermal emission from the stars, or non-thermal charge exchange from the astrospheres.” — explains CNRS researcher Dimitra Koutroumpa, a co-author of the study.



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