Genetics Plays Important Role in Age At First Sex and Birth (Biology)

  • Hundreds of genetic drivers affect sexual and reproductive behaviour
  • Combined with social factors, these can affect longevity and health

An Oxford-led team, working with Cambridge and international scholars, has discovered hundreds of genetic markers driving two of life’s most momentous milestones – the age at which people first have sex and become parents.

In a paper published today in Nature Human Behaviour, the team linked 371 specific areas of our DNA, called genetic variants (known locations on chromosomes), 11 of which were sex-specific, to the timing of first sex and birth. These variants interact with environmental factors, such as socioeconomic status and when you were born, and are predictors of longevity and later life disease.

Our study has discovered hundreds additional genetic markers that shape this most fundamental part of our lives and have the potential for deeper understanding of infertility, later life disease and longevity

Professor Melinda Mills

The researchers conducted a Genome-Wide Association Study (GWAS), a search across the entire human genome, to see if there is a relationship between reproductive behaviour and a particular genetic variant.  In the largest genomic study conducted to date, they combined multiple data sources to examine age at first sex (N=387,338) and birth (N=542,901) in men and women. They then calculated a genetic score, with all genetic loci combined explaining around 5-6% of the variability in the average age at sexual debut or having a first child.

Professor Melinda Mills, Director of the Leverhulme Centre for Demographic Science at the University of Oxford and Nuffield College, and the study’s first author says, ‘Our study has discovered hundreds additional genetic markers that shape this most fundamental part of our lives and have the potential for deeper understanding of infertility, later life disease and longevity.’

The genetic signals were driven by social factors and the environment but also by reproductive biology, with findings related to follicle-stimulating hormone, implantation, infertility, and spermatid differentiation.

Professor Mills adds ‘We already knew that childhood socioeconomic circumstances or level of education were important predictors of the timing of reproduction. But we were intrigued to find not only hundreds of new genetic variants, but also uncover a relationship with substance abuse, personality traits such as openness and self-control, ADHD and even predictive of some diseases and longevity .’

We were intrigued to find not only hundreds of new genetic variants, but also uncover a relationship with substance abuse, personality traits such as openness and self-control, ADHD and even predictive of some diseases and longevity…We demonstrated that it is a combination of genetics, social predictors and the environment that drives early or late reproductive onset

Professor Mills says, ‘We demonstrated that it is a combination of genetics, social predictors and the environment that drives early or late reproductive onset. It was incredible to see that the genetics underlying early sex and fertility were related to behavioural dis-inhibition, like ADHD, but also addiction and early smoking. Or those genetically prone to postpone sex or first birth had better later life health outcomes and longevity, related to a higher socioeconomic status in during childhood.’

Genetic factors driving reproductive behaviour are strongly related to  later life diseases such as Type 2 diabetes and cardiovascular disease.

‘It is exciting that the genetics underlying these reproductive behaviours may help us understand later life disease.’

Professor Mills concludes, ‘Starting your sexual journey early is rooted in childhood inequality but also has links with health problems, such as cervical cancer and depression. We found particularly strong links between early sexual debut, ADHD and substance abuse, such as early age at smoking. We hope our findings lead to better understanding of teenage mental and sexual health, infertility, later life disease and treatments to help.’

Featured image: Hundreds of inherited genetic markers have the potential for deeper understanding of infertility, later life disease and longevity. Credit: Shutterstock.


Reference: Mills, M.C., Tropf, F.C., Brazel, D.M. et al. Identification of 371 genetic variants for age at first sex and birth linked to externalising behaviour. Nat Hum Behav (2021). https://doi.org/10.1038/s41562-021-01135-3


Provided by University of Oxford

Researchers Observed A Crystal That Consists Only Of Electrons (Physics)

Researchers at ETH Zurich have succeeded in observing a crystal that consists only of electrons. Such Wigner crystals were already predicted almost ninety years ago but could only now be observed directly in a semiconductor material.

Crys­tals have fas­cin­ated people through the ages. Who hasn’t ad­mired the com­plex pat­terns of a snow­flake at some point, or the per­fectly sym­met­rical sur­faces of a rock crys­tal? The ma­gic doesn’t stop even if one knows that all this res­ults from a simple in­ter­play of at­trac­tion and re­pul­sion between atoms and elec­trons. A team of re­search­ers led by Ataç Im­amoğlu, pro­fessor at the In­sti­tute for Quantum Elec­tron­ics at ETH Zurich, have now pro­duced a very spe­cial crys­tal. Un­like nor­mal crys­tals, it con­sists ex­clus­ively of elec­trons. In do­ing so, they have con­firmed a the­or­et­ical pre­dic­tion that was made al­most ninety years ago and which has since been re­garded as a kind of holy grail of con­densed mat­ter phys­ics. Their res­ults were re­cently pub­lished in the sci­entific journal “Nature”.

A decades-​old pre­dic­tion

“What got us ex­cited about this prob­lem is its sim­pli­city”, says Im­amoğlu. Already in 1934 Eu­gene Wigner, one of the founders of the the­ory of sym­met­ries in quantum mech­an­ics, showed that elec­trons in a ma­ter­ial could the­or­et­ic­ally ar­range them­selves in reg­u­lar, crystal-​like pat­terns be­cause of their mu­tual elec­trical re­pul­sion. The reas­on­ing be­hind this is quite simple: if the en­ergy of the elec­trical re­pul­sion between the elec­trons is lar­ger than their mo­tional en­ergy, they will ar­range them­selves in such a way that their total en­ergy is as small as pos­sible.

For sev­eral dec­ades, how­ever, this pre­dic­tion re­mained purely the­or­et­ical, as those “Wigner crys­tals” can only form un­der ex­treme con­di­tions such as low tem­per­at­ures and a very small num­ber of free elec­trons in the ma­ter­ial. This is in part be­cause elec­trons are many thou­sands of times lighter than atoms, which means that their mo­tional en­ergy in a reg­u­lar ar­range­ment is typ­ic­ally much lar­ger than the elec­tro­static en­ergy due to the in­ter­ac­tion between the elec­trons.

Elec­trons in a plane

To over­come those obstacles, Im­amoğlu and his col­lab­or­at­ors chose a wafer-​thin layer of the semi­con­ductor ma­ter­ial mo­lyb­denum disel­en­ide that is just one atom thick and in which, there­fore, elec­trons can only move in a plane. The re­search­ers could vary the num­ber of free elec­trons by ap­ply­ing a voltage to two trans­par­ent graphene elec­trodes, between which the semi­con­ductor is sand­wiched. Ac­cord­ing to the­or­et­ical con­sid­er­a­tions the elec­trical prop­er­ties of mo­lyb­denum disel­en­ide should fa­vour the form­a­tion of a Wigner crys­tal – provided that the whole ap­par­atus is cooled down to a few de­grees above the ab­so­lute zero of minus 273.15 de­grees Celsius.

How­ever, just pro­du­cing a Wigner crys­tal is not quite enough. “The next prob­lem was to demon­strate that we ac­tu­ally had Wigner crys­tals in our ap­par­atus”, says To­masz Smoleński, who is the lead au­thor of the pub­lic­a­tion and works as a postdoc in Im­amoğlu’s labor­at­ory. The sep­ar­a­tion between the elec­trons was cal­cu­lated to be around 20 nano­metres, or roughly thirty times smal­ler than the wavelength of vis­ible light and hence im­possible to re­solve even with the best mi­cro­scopes.

Electrons in a material usually behave like a disordered liquid (left), but can form a regular Wigner crystal (right) under particular conditions.
Elec­trons in a ma­ter­ial usu­ally be­have like a dis­ordered li­quid (left), but can form a reg­u­lar Wigner crys­tal (right) un­der par­tic­u­lar con­di­tions.   © ETH Zurich

De­tec­tion through ex­citons

Us­ing a trick, the phys­i­cists man­aged to make the reg­u­lar ar­range­ment of the elec­trons vis­ible des­pite that small sep­ar­a­tion in the crys­tal lat­tice. To do so, they used light of a par­tic­u­lar fre­quency to ex­cite so-​called ex­citons in the semi­con­ductor layer. Ex­citons are pairs of elec­trons and “holes” that res­ult from a miss­ing elec­tron in an en­ergy level of the ma­ter­ial. The pre­cise light fre­quency for the cre­ation of such ex­citons and the speed at which they move de­pend both on the prop­er­ties of the ma­ter­ial and on the in­ter­ac­tion with other elec­trons in the ma­ter­ial – with a Wigner crys­tal, for in­stance.

The peri­odic ar­range­ment of the elec­trons in the crys­tal gives rise to an ef­fect that can some­times be seen on tele­vi­sion. When a bi­cycle or a car goes faster and faster, above a cer­tain ve­lo­city the wheels ap­pear to stand still and then to turn in the op­pos­ite dir­ec­tion. This is be­cause the cam­era takes a snap­shot of the wheel every 40 mil­li­seconds. If in that time the reg­u­larly spaced spokes of the wheel have moved by ex­actly the dis­tance between the spokes, the wheel seems not to turn any­more. Sim­il­arly, in the pres­ence of a Wigner crys­tal, mov­ing ex­citons ap­pear sta­tion­ary provided they are mov­ing at a cer­tain ve­lo­city de­term­ined by the sep­ar­a­tion of the elec­trons in the crys­tal lat­tice.

First dir­ect ob­ser­va­tion

“A group of the­or­et­ical phys­i­cists led by Eu­gene Demler of Har­vard Uni­ver­sity, who is mov­ing to ETH this year, had cal­cu­lated the­or­et­ic­ally how that ef­fect should show up in the ob­served ex­cit­a­tion fre­quen­cies of the ex­citons – and that’s ex­actly what we ob­served in the lab”, Im­amoğlu says. In con­trast to pre­vi­ous ex­per­i­ments based on planar semi­con­duct­ors, in which Wigner crys­tals were ob­served in­dir­ectly through cur­rent meas­ure­ments, this is a dir­ect con­firm­a­tion of the reg­u­lar ar­range­ment of the elec­trons in the crys­tal. In the fu­ture, with their new method Im­amoğlu and his col­leagues hope to in­vest­ig­ate ex­actly how Wigner crys­tals form out of a dis­ordered “li­quid” of elec­trons.

Featured image: A Wigner crys­tal of elec­trons (red) in­side a semi­con­ductor ma­ter­ial (blue/grey).© ETH Zurich


Ref­er­ence

Smoleński T, Dol­girev PE, Kuh­len­kamp C et al. Sig­na­tures of Wigner crys­tal of elec­trons in a mono­layer semi­con­ductor. Nature 595, 53–57 (2021) .DOI: 10.1038/s41586-​021-03590-4


Provided by ETH Zurich

The World’s First Digital Model Of A Cancer Cell (Medicine)

The computer model, developed under the lead management of researchers at TU Graz, simulates the cyclical changes in the membrane potential of a cancer cell using the example of human lung adenocarcinoma and opens up completely new avenues in cancer research.

Computer models have been standard tools in basic biomedical research for many years. However, around 70 years after the first publication of an ion current model of a nerve cell by Hodgkin & Huxley in 1952, researchers at Graz University of Technology (TU Graz), in collaboration with the Medical University of Graz and the Memorial Sloan Kettering Cancer Center in New York, have finally succeeded in developing the world’s first cancer cell model, thus launching “an essential tool for modern cancer research and drug development,” reports a delighted Christian Baumgartner. The head of the Institute of Health Care Engineering with European Testing Center of Medical Devices at TU Graz is senior author of the publication in which the digital model is presented in the journal PLoS Computational Biology.

Excitable and non-excitable cells

Digital cell models have so far focused on excitable cells such as nerve or cardiac muscle cells, allowing the simulation of electrophysiological processes not only at the cellular level, but also at the tissue and organ level. These models are already being used to support diagnosis and therapy in everyday clinical practice. The international research team led by Baumgartner focused on the specific electrophysiological properties of non-excitable cancer cells for the first time.

In excitable cells, an electrical stimulus triggers so-called action potentials. This leads to short-term changes in electrical potential lasting milliseconds at the cell membrane that transmit “electrical” information from cell to cell. Through this mechanism, neural networks communicate or the heart muscle is activated, which contracts as a result. It is known from experimental studies that “non-excitable” cells also exhibit characteristic fluctuations of potential at the cell membrane. However, compared to excitable cells, the potential changes occur very slowly and over the entire cell cycle, i.e. over hours and days, and serve as a signal for the transition between the individual cell cycle phases,” explains Christian Baumgartner. Together with the deputy head of the institute, Theresa Rienmüller, and PhD student Sonja Langthaler, Christian Baumgartner was the first to pursue the idea of developing a simulation model of these mechanisms.

Lung tumour example

Pathological changes in cell membrane voltage, particularly during the cell cycle, are fundamental to cancer development and progression. Sonja Langthaler continues in detail: “Ion channels connect the outside to the inside of a cell. They enable the exchange of ions such as potassium, calcium or sodium and thereby regulate the membrane potential. Changes in the composition of ion channels, as well as altered functional behaviour of the same, can result in disruptions in cell division, possibly even affecting cell differentiation and thus transforming a healthy cell into a diseased (carcinogenic) cell.”

For their digital cancer cell model, the team chose the example of the human lung adenocarcinoma cell line A549. The computer model simulates the rhythmic oscillation of the membrane potential during the transition between cell cycle phases and enables prediction of the changes in membrane potential that are caused by drug-induced switching on and off of selected ion channels. “So we get information about the effects of targeted interventions on the cancer cell,” Baumgartner adds.

“Freezing” cancer cells during growth or inducing them to commit suicide

The activity of certain ion channels can also drive the division of diseased cells and thus accelerate tumour growth. If ion channels are now manipulated in a targeted manner, as is the case with new, promising agents and drugs, the cell membrane voltage and thus the entire electrophysiological system can be thrown off track, so to speak. “This could be used to arrest cancer cells at a certain phase in the cell cycle, but also to induce premature cell death (apoptosis). One could “freeze” cancer cells while they are growing or induce them to commit suicide. And it is precisely such mechanisms that can be simulated with the help of models.” Baumgartner and his team see the first digital cancer cell model as the beginning of more comprehensive research. In order to increase the level of detail of the model, plans for further experimental and measurement validations have been made and submitted to the Austrian Science Fund FWF for funding.

Publication details:
“A549 in-silico 1.0: A first computational model to simulate cell cycle dependent ion current modulation in the human lung adenocarcinoma”. Sonja Langthaler, Theresa Rienmüller, Susanne Scheruebel, Brigitte Pelzmann, Niroj Shrestha, Klaus Zorn-Pauly, Wolfgang Schreibmayer, Andrew Koff and Christian Baumgartner. PLoS Compuational Biology, June 2021. https://doi.org/10.1371/journal.pcbi.1009091

This research is anchored in the Field of Expertise “Human & Biotechnology”, one of five strategic research focuses of TU Graz.

Featured image: With the first cancer cell model, researchers at TU Graz were able to launch an essential tool for modern cancer research and drug development. Pictured: a graphical representation of a dividing cancer cell. © peterschreiber.media – AdobeStock


Provided by Tu Graz

Astronomers Proposed A Python Package To Model Asymmetric Light Curves (Astronomy)

When exoplanets pass in front of their stars, they imprint a transit signature on the stellar light curve which to date has been assumed to be symmetric in time, owing to the planet being modelled as a circular area occulting the stellar surface. However, this signature might be asymmetric due to different temperature/pressure and/or chemical compositions in the different terminator regions of the transiting planet. If we could be able to model these asymmetric signatures directly from transit light curves it could give us an unprecedented glimpse into planetary 3-D structure, helping constrain models of atmospheric evolution, structure and composition.

Now, Kathryn Jones and Nestor Espinoza proposed a Python package called “catwoman”, which allows us to model these asymmetric transit lightcurves and calculate them (lightcurves) for any radially symmetric stellar limb darkening law. Their study appeared in Journal of Open Source Software.

In order to obtain the desired light curves, catwoman first calculates many models, with varying widths and geometrically searches for a width that produces an error less than 1% away (and always less than) the specified level. The model then uses this width value to calculate the light curves. A lower specified error, and therefore thinner iso-intensity bands, produces more accurate light curves.

In catwoman, we can model planets as two semi-circles, of different radii, using the integration algorithm. It also allows for φ, the angle of rotation of the semi-circles, to vary as a free parameter, which is something no other model has tried to implement, accounting for the possibility of spin-orbit misalignments of the planet.

It was designed to be used by astronomical researchers. For a realistic light curve with 100 in-transit data points, catwoman takes around 340 seconds to produce 1 million quadratic-limb-darkened light curves on a single 1.3 GHz Intel Core i5 processor. It is used in Espinoza & Jones (in prep.)

It is fast and efficient and open source with full documentation available to view at
https://catwoman.readthedocs.io .

Featured image: Diagram of the geometric configuration during transit of two stacked semi-circles (one of radius Rp,1, and another of radius Rp,2) that model the different limbs of an exoplanet transiting in front of a star. The area of the star has been divided in different sections of radius xi (dashed circles) — between each subsequent section, the star is assumed to have a radially symmetric intensity profile (e.g., blue band between x_i–1 and xi above). In order to obtain the light curve, the challenge is to calculate the sum of the intersectional areas between a given iso-intensity band and the semi-circles, ∆A (blue band with dashed grey lines). Note the stacked semi-circles are inclined by an angle φ with respect to the planetary orbital motion. © Jones et al.


Reference: Jones et al., (2020). catwoman: A transit modelling Python package for asymmetric light curves. Journal of Open Source Software, 5(55), 2382, https://doi.org/10.21105/joss.02382


Note for editors of other websites: To reuse this article fully or partially kindly give credit either to our author/editor S. Aman or provide a link of our article

Using Targeted Therapy to Treat Breast Cancer (Medicine)

Proton therapy is a newer type of radiation therapy that uses energy from positively charged particles called protons. Studies have suggested that proton therapy may cause fewer side effects than traditional radiation, since doctors can better control where the proton beams deposit their energy.

In this Mayo Clinic Minute, Dr. Robert Mutter, a Mayo Clinic radiation oncologist, explains potential long-term advantages of using targeted therapy to treat breast cancer.

Watch: The Mayo Clinic Minute.

Journalists: Broadcast-quality video (1:03) is in the downloads at the end of this post. Please courtesy: “Mayo Clinic News Network.” Read the script.

Unlike traditional X-ray radiation, proton beam therapy can more precisely target tumors, sparing more normal tissue.

“The main advantage is this idea of sparing normal tissues and reducing late side effects of treatment. This is especially important in breast cancer,” says Dr. Mutter.

Dr. Mutter says because the heart sits right behind breast tissue, using protons to target breast cancer tumors can reduce the radiation dose to the heart and lungs, and may offer better outcomes for patients.

“We think that that’s going to lead to less risk of heart disease, and less risk of lung disease or second cancers in the future,” says Dr. Mutter.

In recent years, Dr. Mutter says studies have shown the potential to safely shorten the course of radiation treatment for breast cancer.

“We think that protons may be a way that we can do this even more effectively because protons expose less normal tissues. If we can reduce the number of daily treatments, that means that my patients are able to be back with their families, or back at their work or the things that they love to do, and not coming in for their treatment,” he says.


Provided by Mayo Clinic

Understanding the Role of BRN2 in Melanoma (Medicine)

The initiation of cancer requires both the activation of oncogenes and the loss of tumor suppressor activity. The major oncogenes that drive melanoma, an aggressive skin cancer, are well known and mutations that affect the activity of tumor suppressors such as PTEN have been characterized. But less is known about whether and how the levels of tumor suppressor affect total tumor suppressor activity in this cancer.

A study jointly led by Ludwig Oxford’s Colin Goding and Lionel Larue of the Institut Curie, in France, identified BRN2 as a tumor suppressor that regulates PTEN levels. The researchers report in Nature Communications that BRN2 is a key transcription factor that lies downstream of three melanoma-associated signaling pathways to control gene expression. A role for BRN2 in melanoma migration and invasiveness had previously been established through in vitro and xenograft experiments, but this is the first time that the function of BRN2 in melanoma initiation and proliferation has been demonstrated in an animal model engineered to develop melanoma.

The authors also uncovered a link between BRN2 loss or low levels and worse prognosis for patients with melanoma. Together with previous collaborative observations from the Goding and Larue groups showing BRN2 is linked to a high mutation burden and marks a distinct subpopulation of melanoma cells in tumors, the study reinforces the importance of this factor in the cancer.


Reference: Hamm, M., Sohier, P., Petit, V. et al. BRN2 is a non-canonical melanoma tumor-suppressor. Nat Commun 12, 3707 (2021). https://doi.org/10.1038/s41467-021-23973-5


Provided by Ludwig Cancer Research

Drug Dissolved Net-like Structures in Airways of Severely Ill Covid-19 Patients (Medicine)

When researchers at Lund University in Sweden performed advanced analyses of sputum from the airways of severely ill Covid-19 patients, they found high levels of neutrophil extracellular traps (NETs). It is already a known fact that NETs can contribute to sputum thickness, severe sepsis-like inflammation and thrombosis. After being treated with an already existing drug, the NETs were dissolved and patients improved. The study has now been published in Molecular & Cellular Proteomics.

Using advanced fluorescence microscopy, the researchers examined sputum in the airways of three severely ill Covid-19 patients. The results showed that the samples contained large amounts of one of the immune system’s most important agents against bacteria: neutrophils. Neutrophils can form neutrophil extracellular traps (NETs) to capture and neutralise pathogens – primarily bacteria but also viruses.

“We are aware that NETs contribute to sputum viscosity and severe sepsis-like inflammation as well as increase risk of thrombosis i.e. blood clots. We also see these three clinical findings in severely ill Covid-19 patients”, says Adam Linder, researcher at Lund University and infectious disease physician at Skåne University Hospital.

Patients with cystic fibrosis can also suffer from increased sputum viscosity. In these cases, a DNase drug is sometimes used to degrade DNA, of which NETs are primarily composed. Could the same drug have an effect on severe Covid 19 cases? A pilot study was conducted after the researchers could see in laboratory test tubes that the DNase preparation degraded the NETs. Five severely ill Covid-19 patients, who required high-flow oxygen therapy and were on the verge of needing mechanical ventilation, were treated with the preparation.

“The patients responded very well to the treatment. Dependency on oxygen therapy diminished for all of them, and they no longer needed oxygen therapy at all after four days. None of them needed to be moved to the intensive care unit, and all of them have recovered and been discharged”, says Adam Linder.

Analyses of the patients’ sputum showed that they had high levels of NETs prior to the start of treatment, and that these levels were substantially reduced after treatment (see image).

“We have also examined other inflammation parameters using advanced mass spectrometry. Once the drug treatment started, the proinflammatory signalling diminished, which shows that the inflammation was subsiding. Plasma leakage and the viral load were also reduced”, says Tirthankar Mohanty, researcher at Lund University.

Even if the results are positive, Adam Linder emphasises that the study is small and that additional research is needed. The researchers are consequently carrying out a phase-2, randomised clinical trial at Skåne University Hospital to examine whether aerosolised DNase (Pulmozyme) is an effective treatment for respiratory failure in conjunction with Covid-19.

“Much of what we see in patients with this pathology could be explained by NETs, but the study needs to be repeated, and in a randomised manner. We also need to know more about when the drug should be administered for the best results”, concludes Adam Linder.

Publication:

Link to the article in Molecular & Cellular Proteomics:

Proteome profiling of recombinant DNase therapy in reducing NETs and aiding recovery in COVID-19 patients

Funding:

The research has been made possible by funding from the Swedish Research Council, ALF funding, The Crafoord Foundation, the Alfred Österlund Foundation and the Wenner-Gren Foundations.

Advanced microscopy sheds light on proteins

One of the technologies used by the researchers is mass spectrometry, which is one way to map large amounts of protein. Tirthankar Mohanty performed the analyses and says the technology is a game changer.

“We previously studied one protein at a time, but today we can use mass spectrometry to examine thousands of proteins at once – and at the same time obtain information about how they change in relation to one another. Patients with Covid-19 are at risk of suffering severe oxygen deprivation, in which case the composition of proteins in the blood also changes. This is something we can measure, and we also see how the proteins change when patients are treated and oxygen levels increase”, says Tirthankar Mohanty.

Featured image: The image to the far left is from sputum prior to treatment with the DNase drug. The one in the middle was taken 3.5 days after treatment, and the one to the far right was taken the day the patient was discharged. © Lund University


Provided by Lund University

Why Are Some Fish Warm-blooded When Most Are Not? (Biology)

New research from marine biologists offers answers to a fundamental puzzle that had until now remained unsolved: why are some fish warm-blooded when most are not?

It turns out that while (warm-blooded) fish able to regulate their own body temperatures can swim faster, they do not live in waters spanning a broader range of temperatures.

The research therefore provides some of the first direct evidence as to the evolutionary advantage of being warm-blooded as well as underlining that species in this demographic – such as the infamous white shark and the speedy bluefin tuna – are likely just as vulnerable to changing global ocean temperatures as their cold-blooded relatives.

Lucy Harding, PhD Candidate in Trinity’s School of Natural Sciences, is the first author of the associated research article, which has just been published in the journal, Functional Ecology. She said:

“Scientists have long known that not all fish are cold-blooded. Some have evolved the ability to warm parts of their bodies so that they can stay warmer than the water around them, but it has remained unclear what advantages this ability provided.

“Some believed being warm-blooded allowed them to swim faster, as warmer muscles tend to be more powerful, while others believed it allowed them to live in a broader range of temperatures and therefore be more resilient to the effects of ocean warming as a result of climate change.”

Lucy and her international team of collaborators assessed these two possibilities by collecting data from wild sharks and bony fish, as well as using existing databases.

By attaching biologging devices to the fins of the animals they caught, they were able to collect information such as water temperatures encountered by the fish in their habitats; the speeds at which the fish swam for most of the day; and the depths of water the fish swam in.

The results showed that warm-blooded fishes swim approximately 1.6 times faster than their cold-blooded relatives, but they did not live in broader temperature ranges.

Nick Payne, Assistant Professor in Zoology in Trinity’s School of Natural Sciences, said:

“The faster swimming speeds of the warm-blooded fishes likely gives them competitive advantages when it comes to things like predation and migration. With predation in mind, the hunting abilities of the white shark and bluefin tuna help paint a picture of why this ability might offer a competitive advantage.

“Additionally, and contrary to some previous studies and opinions, our work shows these animals do not live in broader temperature ranges, which implies that they may be equally at risk from the negative impacts of ocean warming. Findings like these – while interesting on their own – are very important as they can aid future conservation efforts for these threatened animals.”

The research was supported by Science Foundation Ireland.

Featured image: A white shark (Carcharodon carcharias) swimming at the surface with a biologging package attached to dorsal fin. This package records temperature, swimming speed, depth, body movement and video footage. Image credit: Andrew Fox.


Provided by Trinity College Dublin

Non-stop Signal Achieved in High-power Er3+-doped Mid-infrared Lasers (Physics)

The Mid-infrared lasers (MIR) with high peak power and high repetition rate operating in the range of 2.7~3 μm have important application in laser surgery and optical parametric oscillator (OPO).

A recent study conducted by SUN Dunlu’s research group at the Hefei Institutes of Physical Science(HFIPS) of the Chinese Academy of Sciences (CAS) achieved high power, high efficiency and quasi-continuous mid-infrared laser in the free running and langasite [La3 Ga5 SiO14 (LGS)] Q-switched modes by using the Er3+ ions-doped YAP crystals as laser gain medium.

Based on their previous research work on laser, the researchers further improved the laser performance of Er:YAP laser crystal by laser-diode (LD) side-pumping method, a Er:YAP crystal rod with concave end-faces was used to compensate the thermal lensing effect. The maximum output powers of 26.75 W were achieved at 250 Hz, and 13.18 W at 1000 Hz, which is the highest working frequency in all the LD side- pumped Er-doped MIR laser so far.

In addition, they demonstrated a LD side-pumped and electro-optical Q-switched Er,Pr:YAP laser with emission at 2.7 μm. A giant pulse laser was obtained with pulse energy of 20.5 mJ, pulse width of 61.4 ns, and peak power of 0.33 MW at the highest working frequency of 150 Hz.

These results indicate that the Er3+-doped YAP crystals are promising candidate for the high power and high frequency mid-infrared laser device, which possess great potential for the application of dental ablation surgery and OPO pump source.

This work was supported by the National Key Research and Development Program of China, the National Natural Science Foundation of China, the Natural Science Foundation of Anhui Province, and the Youth Fund of Advanced Laser Technology Laboratory of Anhui Province.

Fig. Average output power of LD side-pumped Er:YAP laser versus pump power at different working frequencies and pump pulse widths. (Image by QUAN Cong)

Featured image: Schematic of LD side-pumped Er(Pr):YAP laser (Image by QUAN Cong)


References: (1) Cong Quan, Dunlu Sun, Huili Zhang, Jianqiao Luo, Lunzhen Hu, Zhiyuan Han, Kunpeng Dong, Yuwei Chen, and Maojie Cheng, “13-W and 1000-Hz of a 2.7-µm laser on the 968 nm LD side-pumped Er:YAP crystal with concave end-faces,” Opt. Express 29, 21655-21663 (2021). Link to paper (2) Cong Quan et al., “Performance of a 968-nm laser-diode side-pumped, electro-optical Q-switched Er,Pr:YAP laser with emission at 2.7  μm”, Optical Engineering, 60(6), 066112 (2021). https://doi.org/10.1117/1.OE.60.6.066112


Provided by Chinese Academy of Sciences