The latter examples are so-called “regional endotherms” and are all fast swimming, apex predators at the top of the food chain. Scientists have long reasoned that their ability to keep warm helped with this athletic predatory lifestyle, and that evolution had shaped their physiology to match their requirements.

However, an international team of researchers led by those from Trinity College Dublin, has now shown that gentle, plankton-feeding basking sharks are also regional endotherms despite having very different lifestyles to white sharks and tunas.

This surprising discovery has implications for conservation, as well as raising a plethora of ecological and evolutionary questions.

Haley Dolton, PhD Candidate in Trinity’s School of Natural Sciences, was lead author of the study that has just been published in international journal, Endangered Species Research. She said:

“The basking shark is a shining example of how little we know about shark species in general. That we still have lots to uncover about the second biggest fish in the world — such a huge, charismatic animal that most people would recognise it — just highlights the challenge facing researchers to gather what they can about species to aid in effective conservation strategies.

Basking sharks gained legal protection in Irish waters just last year, with the species having undergone significant population declines throughout the NE Atlantic in the last century. But they still face many challenges in the future.

Haley Doltonadded: “Regional endotherms are thought to use more energy, and possibly respond differently to ocean warming than other fish species. So lots more work will need to be done to work out how these new findings regarding an endangered species might change previous assumptions about their metabolism or potential distribution shifts during our climate crisis, which is something marine biologists are focusing on as our planet and its seas continue to warm.

“Hopefully this kind of research will continue the momentum needed to effectively protect these incredible animals in Irish waters and further afield.”

To make the discovery, the research team (including scientists from University of Pretoria, Marine Biological Association, Queen’s University Belfast, Zoological Society of London, University of Southampton, and Manx Basking Shark Watch) first undertook dissections of dead basking sharks that washed up in Ireland and the UK.

They found that the sharks have cruise-swimming muscles located deep inside their bodies as seen in white sharks and tunas; in most fish this “red” muscle is instead found toward the outside of the animals.

They also discovered basking sharks have strong muscular hearts that probably help generate high blood pressures and flows. Most fish species have relatively “spongy” hearts, whereas basking shark hearts are more typical of the regional endotherm species.

Next, the team designed a new low-impact tagging method to record body temperature of free-swimming basking sharks off the coast of Co Cork, Ireland. Researchers were able get close enough to 8 m basking sharks to safely deploy the tags, which recorded muscle temperature just under the skin for up to 12 hours before they automatically detached from the animals and were collected by the researchers.

These tags revealed that basking shark muscles are consistently elevated above water temperatures, and to almost exactly the same extent as their regionally-endothermic predatory cousins.

Nicholas Payne, Assistant Professor in Trinity’s School of Natural Sciences, was senior author of the study. He said:

“These results cast an interesting new light on our perception of form versus function in fishes because until now we thought regional endothermy was only found in apex predatory species living at high positions in the marine food web.

“Now we have found a species that grazes on tiny plankton but also shares those rather uncommon regional endotherm features, so we might have to adjust our assumptions about the advantages of such physiological innovations for these animals.

“It’s a bit like suddenly finding that cows have wings.”

“The motivation of this project was really to try and understand how these post-reproductive females are helping their offspring,” says first author Charli Grimes, an animal-behavior scientist at the University of Exeter. “Our results highlight a new pathway by which menopause is adaptive in killer whales.”

The research team studied southern resident orcas, a group of orcas that live off the Pacific Northwest coast. These killer whales live in matriarchal social units that consist of a mother, her offspring, and the offspring of her daughters. Although male orcas will outbreed with whales from other pods, both males and females stay in their unit of birth, with their mother, for life.

Using data from the Center for Whale Research’s annual photographic census of the orca population, the researchers looked for evidence of scarring on each catalogued whale’s skin. Killer whales have no natural predators other than humans, so a tooth mark that is able to puncture an orca’s skin was most likely inflicted by another orca.

The study found that, if a given male’s mother was still alive and no longer reproducing, that male would have fewer tooth marks than his motherless peers or his peers with a mother who was still reproducing.

“It was striking to see how directed the social support was,” says senior author Darren Croft, an animal-behavior scientist at the University of Exeter. “If you have a post-reproductive mother who’s not your mother within the social group, there’s no benefit. It’s not that these females are performing a general policing role. These post-reproductive mothers are targeting the support they are giving to their sons.”

The researchers still can’t say for certain what kinds of social conflicts are leading to tooth marks or how older females are protecting their sons against them. They do note that post-menopause females have the lowest incidence of tooth marks in the entire social unit, suggesting that they do not physically intervene in a conflict. If older orca females play a similar role to that of older women in human societies, they might be acting as mediators, preventing conflict from occurring in the first place. To explore this further, the researchers plan on completing an additional study by using drone footage to observe whale behavior from above.

“It’s possible that with age comes advanced social knowledge. Over time, they might have a better understanding of other social groups,” says Grimes. “Given these close mother-son associations, it could also be that she is present in a situation of conflict so she can signal to her sons to avoid the risky behavior they might be participating in.”

“We’ve got hypotheses, but we need to test them by seeing what’s happening under water when these different groups interact,” says Croft. “We’ve learned so much from this population, but we’ve still got so much to learn from them.”

The object could be an ultra-long period magnetar, a rare type of star with extremely strong magnetic fields that can produce powerful bursts of energy.

Until recently, all known magnetars released energy at intervals ranging from a few seconds to a few minutes. The newly discovered object emits radio waves every 22 minutes, making it the longest period magnetar ever detected.

The research was published today in the journal Nature.

Astronomers discovered the object using the Murchison Widefield Array (MWA), a radio telescope on Wajarri Yamaji Country in outback Western Australia.

Lead author Dr Natasha Hurley-Walker said the magnetar, named GPM J1839-10, is 15,000 light-years away from Earth in the Scutum constellation.

“This remarkable object challenges our understanding of neutron stars and magnetars, which are some of the most exotic and extreme objects in the Universe,” she said.

The stellar object is only the second of its kind ever detected after the first was discovered by Curtin University undergraduate research student Tyrone O’Doherty.

Initially, scientists could not explain what they had found.

They published a paper in Nature in January 2022 describing an enigmatic transient object that would intermittently appear and disappear, emitting powerful beams of energy three times per hour.

Dr Hurley-Walker — O’Doherty’s honours supervisor — said the first object took us by surprise.

“We were stumped,” she said. “So we started searching for similar objects to find out if it was an isolated event or just the tip of the iceberg.”

Between July and September 2022, the team scanned the skies using the MWA telescope.

They soon found what they were looking for in GPM J1839-10.

It emits bursts of energy that last up to five minutes — five times longer than the first object.

Other telescopes followed up to confirm the discovery and learn more about the object’s unique characteristics.

These included three CSIRO radio telescopes in Australia, the MeerKAT radio telescope in South Africa, the Grantecan (GTC) 10m telescope, and the XMM-Newton space telescope.

Armed with GPM J1839-10’s celestial coordinates and characteristics, the team also began searching the observational archives of the world’s premier radio telescopes.

“It showed up in observations by the Giant Metrewave Radio Telescope (GMRT) in India, and the Very Large Array (VLA) in the USA had observations dating as far back as 1988,” she said.

“That was quite an incredible moment for me. I was five years old when our telescopes first recorded pulses from this object, but no one noticed it, and it stayed hidden in the data for 33 years.

“They missed it because they hadn’t expected to find anything like it.”

Not all magnetars produce radio waves. Some exist below the ‘death line’, a critical threshold where a star’s magnetic field becomes too weak to generate high-energy emissions.

“The object we’ve discovered is spinning way too slowly to produce radio waves — it’s below the death line,” Dr Hurley-Walker said.

“Assuming it’s a magnetar, it shouldn’t be possible for this object to produce radio waves. But we’re seeing them.

“And we’re not just talking about a little blip of radio emission.

“Every 22 minutes, it emits a five-minute pulse of radio wavelength energy, and it’s been doing that for at least 33 years.

“Whatever mechanism is behind this is extraordinary.”

The discovery has important implications for our understanding of the physics of neutron stars and the behaviour of magnetic fields in extreme environments.

It also raises new questions about the formation and evolution of magnetars and could shed light on the origin of mysterious phenomena such as fast radio bursts.

The research team plans to conduct further observations of the magnetar to learn more about its properties and behaviour.

They also hope to discover more of these enigmatic objects in the future, to determine whether they are indeed ultra-long period magnetars, or something even more phenomenal.

“Two decades ago it was predicted in theory that pairs of planets of similar mass may share the same orbit around their star, the so-called Trojan or co-orbital planets. For the first time, we have found evidence in favour of that idea,” says Olga Balsalobre-Ruza, a student at the Centre for Astrobiology in Madrid, Spain who led the paper published today in Astronomy & Astrophysics.

Trojans, rocky bodies in the same orbit as a planet, are common in our own Solar System [1], the most famous example being the Trojan asteroids of Jupiter — more than 12,000 rocky bodies that are in the same orbit around the Sun as the gas giant. Astronomers have predicted that Trojans, in particular Trojan planets, could also exist around a star other than our Sun, but evidence for them is scant. “Exotrojans [Trojan planets outside the Solar System] have so far been like unicorns: they are allowed to exist by theory but no one has ever detected them,” says co-author Jorge Lillo-Box, a senior researcher at the Centre for Astrobiology.

Now, an international team of scientists have used ALMA, in which ESO is a partner, to find the strongest observational evidence yet that Trojan planets could exist — in the PDS 70 system. This young star is known to host two giant, Jupiter-like planets, PDS 70b and PDS 70c. By analysing archival ALMA observations of this system, the team spotted a cloud of debris at the location in PDS 70b’s orbit where Trojans are expected to exist.

Trojans occupy the so-called Lagrangian zones, two extended regions in a planet’s orbit where the combined gravitational pull of the star and the planet can trap material. Studying these two regions of PDS 70b’s orbit, astronomers detected a faint signal from one of them, indicating that a cloud of debris with a mass up to roughly two times that of our Moon might reside there.

The team believes this cloud of debris could point to an existing Trojan world in this system, or a planet in the process of forming. “Who could imagine two worlds that share the duration of the year and the habitability conditions? Our work is the first evidence that this kind of world could exist,” says Balsalobre-Ruza. “We can imagine that a planet can share its orbit with thousands of asteroids as in the case of Jupiter, but it is mind blowing to me that planets could share the same orbit.”

“Our research is a first step to look for co-orbital planets very early in their formation,” says co-author Nuria Huélamo, a senior researcher at the Centre for Astrobiology. “It opens up new questions on the formation of Trojans, how they evolve and how frequent they are in different planetary systems,” adds Itziar De Gregorio-Monsalvo, ESO Head of the Office for Science in Chile, who also contributed to this research.

To fully confirm their detection, the team will need to wait until after 2026, when they will aim to use ALMA to see if both PDS 70b and its sibling cloud of debris move significantly along their orbit together around the star. “This would be a breakthrough in the exoplanetary field,” says Balsalobre-Ruza.

“The future of this topic is very exciting and we look forward to the extended ALMA capabilities, planned for 2030, which will dramatically improve the array’s ability to characterise Trojans in many other stars,” concludes De Gregorio-Monsalvo.

Notes

[1] When asteroids in Jupiter’s orbit were first discovered, they were named after heroes of the Trojan war, giving rise to the name Trojans to refer to these objects.

The paper, published July, 19, 2023 in Nature, offers the first evidence that there is a genetic basis for asymptomatic SARS-CoV-2. The research helps to solve the mystery of why some people can be infected without ever getting sick from COVID-19. 

The secret lies with the human leukocyte antigen (HLA), or protein markers that signal the immune system. A mutation in one of the genes coding for HLA appears to help virus-killing T cells identify SARS-CoV-2 and launch a lighting attack. The T cells of some people who carry this variant can identify the novel coronavirus, even if they have never encountered it before, thanks to its resemblance to the seasonal cold viruses they already know. The discovery points to new targets for drugs and vaccines.

“If you have an army that’s able to recognize the enemy early, that’s a huge advantage,” explained the study’s lead researcher, Jill Hollenbach, PhD, MPH, professor of neurology, as well as epidemiology and biostatistics, and a member of the Weill Institute for Neurosciences at UCSF. “It’s like having soldiers that are prepared for battle and already know what to look for, and that these are the bad guys.” 

The mutation — HLA-B*15:01 — is quite common, carried by about 10% of the study’s population. It doesn’t prevent the virus from infecting cells but, rather, prevents people from developing any symptoms. That includes a runny nose or even a barely noticeable sore throat. 

UCSF researchers found that 20% of people in the study who remained asymptomatic after infection carried at least one copy of the HLA-B*15:01 variant, compared to 9% of those who reported symptoms. Those who carried two copies of the variant were far more likely — more than eight times — to avoid feeling sick.

Leveraging a national marrow donor database

Researchers suspected early on that HLA was involved, and fortunately a national registry existed that contained the data they were looking for. The National Marrow Donor Program/Be The Match, the largest registry of HLA-typed volunteer donors in the U.S., matches donors with people who need bone marrow transplants.

But they still needed to know how the donors fared against COVID-19. So, they turned to a mobile app developed at UCSF, called the COVID-19 Citizen Science Study. They recruited nearly 30,000 people who were also in the bone marrow registry and tracked through the first year of the pandemic. At that time, vaccines were not yet available, and many people were undergoing routine COVID testing for work or whenever they were potentially exposed.

“We did not set out to study genetics, but we were thrilled to see this result come from our multidisciplinary collaboration with Dr. Hollenbach and the National Marrow Donor Program,” said Mark Pletcher, MD, MPH, a professor of epidemiology and biostatistics at UCSF.

The primary study group was limited to those who self-identified as white because the final set of study respondents did not have enough people in it from other ethnic and racial groups to analyze.

Researchers identified 1,428 unvaccinated donors who tested positive between February 2020 and the end of April 2021, before the vaccines were widely available and when it still took many days to get back test results.

Of these, 136 individuals remained asymptomatic for at least two weeks before and after testing positive. Only one of the HLA variants — HLA-B*15:01 — had a strong association with asymptomatic COVID-19 infection, and this was reproduced in two independent cohorts. Risk factors for severe COVID-19, like being older, overweight and having chronic diseases like diabetes did not appear to play a role in who remained asymptomatic.   

“We are proud to partner on research that has the potential to leverage a long-term public investment in building the national registry to help cure diseases and improve our ability to avoid future pandemics,” said Martin Maiers, vice president of research at the National Marrow Donor Program/Be The Match.

To figure out how HLA-B15 managed to quash the virus, Hollenbach’s team collaborated with researchers from La Trobe University in Australia. They homed in on the concept of T-cell memory, which is how the immune system remembers previous infections. 

The researchers looked at T cells from people who carried HLA-B15 but had never been exposed to the SARS-CoV-2 virus, and found these cells still responded to a part of the novel coronavirus called the NQK-Q8 peptide. They concluded that exposure to some seasonal coronaviruses, which have a very similar peptide, called NQK-A8, enabled T cells in these individuals to quickly recognize SARS-CoV-2 and mount a faster, more effective immune response. 

“By studying their immune response, this might enable us to identify new ways of promoting immune protection against SARS-CoV-2 that could be used in future development of vaccine or drugs,” said Stephanie Gras, a professor and laboratory head at La Trobe University.