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Beneath the waves, vibrant corals thrive alongside diverse marine life, a delicate ecosystem now being studied through eDNA to uncover the subtle impacts of human activities.Photo courtesy of Chuanqi Gong.

HKU Ecologists Unveil Critical Insights into Marine Biodiversity Dynamics Using Environmental DNA

A study led by the eDNA & eEcology lab at the School of Biological Sciences, The University of Hong Kong (HKU) has harnessed environmental DNA (eDNA) to decode the hidden impacts of human activities on marine biodiversity, offering new tools to monitor and combat ecosystem degradation. The study was led by Professor Mathew SEYMOUR, with key support from Ms Vivy Zhewei SI and collaboration with an international team of marine ecologists and geneticists, including Professor David BAKER, the interim Director of the Swire Institute of Marine Science (SWIMS). Their work underscores HKU’s leadership in marine conservation and its commitment to addressing global biodiversity challenges through innovative scientific approaches. The Silent Crisis in Our Oceans Marine biodiversity is under unprecedented threat from human activities, including coastal development, pollution, aquaculture, and overfishing. While the decline of coral reefs and fisheries has garnered global attention, our understanding of the broader impacts on marine ecosystems is still largely lacking. This is partially due to traditional monitoring methods, which rely on labour-intensive surveys and are often limited in their ability to capture the rapid and complex changes occurring in marine environments. To address this, Prof. Seymour’s team utilised eDNA metabarcoding, which offers relatively continuous, high-resolution snapshots of real-time dynamic changes in marine communities, revealing how human stressors disrupt ecosystems. A Race Against Time The study involved deploying 12 large-scale mesocosms (experimental tanks) seeded with Autonomous Reef Monitoring Structures (ARMS) that were previously colonised from natural reef habitats at SWIMS. Over a seven-month period, the team collected 240 eDNA water samples from the mesocosms to analyse three key eDNA and biological phases: 1) biodiversity accumulation, 2) response to human stressors, and 3) eDNA degradation. Species richness (i.e., the number of unique species) initially surged as ARMS were introduced into the mesocosms, stabilised during exposure to human stressors, and plummeted during the degradation phases after ARMS removal. During the response to human stressors phase, it found that aquaculture waste, particularly fish feed, significantly disrupted community composition, favouring groups like Gastropoda while suppressing algae. Significant changes in families such as Lithodesmiaceae (algae) and Haminoeidae (sea snails) highlight their potential as bioindicators under environmental stress. Additionally, the study highlighted variations in eDNA decay rates among species, with fish DNA degrading the fastest while algae and invertebrates persisted longer—a finding that could inform future monitoring strategies. Twelve large-scale mesocosms were involved in this study at HKU’s Swire Institute of Marine Science (SWIMS). Photo courtesy of Vivy Zhewei Si.   Bridging Gaps in Conservation Coral reefs, vital to marine biodiversity, are declining globally due to sedimentation and pollution. Yet, traditional surveys often miss cryptic species or fail to capture fine-scale changes. “eDNA allows us to see the invisible—tracking entire communities in real-time, not just individual species,” explained lead author Zhewei Si. “For the first time, we’ve quantified how stressors like fish feeding alter ecosystems at a molecular level.” While sedimentation and fertiliser treatments showed limited immediate impacts, the stark effects of fish feed underscore the need for stricter aquaculture regulations. “Even legal activities can destabilise ecosystems,” warned the team. “eDNA isn’t just a tool for science—it’s a lifeline for policymakers to act before species vanish.” “This study is just the beginning,” said Professor Seymour. “As we refine eDNA techniques, we’ll be able to improve local and regional monitoring of marine biodiversity, with extension to the global scale, providing the data needed to protect our oceans for generations to come.” Click here to learn more about the research.  Researchers:    Ms Vivy Zhewei SI   Professor Mathew SEYMOUR    

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HKU Biologists Uncover How a Genetic Player Fuels Liver Cancer by Disrupting Fat Metabolism

Figure 1. Mechanism of how genetic player VPS72 impacts liver cancer. Too much VPS72 in cells activates the cancer-promoting pathway, which increases fat production and helps liver cancer grow. This study shows a new connection between fat buildup and liver cancer, suggesting new treatment possibilities. Image adapted from the respective paper at Advanced Science.   Liver cancer is a lethal disease with limited treatment options for advanced stages. While risk factors such as viral hepatitis, alcohol use, and obesity increase the likelihood of hepatocellular carcinoma (HCC, the progression of liver cancer), scientists are racing to uncover the hidden biological mechanisms that fuel tumour growth. Recent research led by Professor Jiangwen ZHANG of the School of Biological Sciences at The University of Hong Kong (HKU) has uncovered how a key genetic culprit, VPS72, drives the development of liver cancer by disrupting fat metabolism and manipulating gene activity. The team’s findings have been published in Advanced Science. The Fat-Liver Cancer Connection The liver is the body’s metabolic powerhouse, responsible for balancing fat production and breakdown. In healthy individuals, this process is tightly controlled. However, in HCC, liver cells accumulate excessive fat droplets, fuelling tumours to grow uncontrollably. This fat buildup is largely controlled by a key cellular pathway known as mTORC1, a molecular switch that activates fat-producing genes, and by SREBP proteins, which act as master regulators that directly control enzymes involved in fat synthesis. In cancer cells, mTORC1 becomes hyperactive, ramping up fat production and creating a vicious cycle that promotes tumour growth. The Role of Genetic Driver VPS72 in Liver Cancer Development Professor Zhang and his team discovered that VPS72, a gene that modifies how DNA is packaged inside cells, is overactive and abnormally amplified (i.e., present in extra copies) in over 50% of HCC patients. This amplification is linked to poorer survival rates, suggesting that this genetic player plays a central role in cancer progression. Here is how the mechanism works:   DNA Packaging: VPS72 helps attach specific proteins to DNA, which affects whether certain genes are turned on or off. Suppressing Protective Genes: VPS72 adds chemical tags to the promoter of gene ATF3, which normally helps prevent cancer growth. This tagging shuts down the production of ATF3, leading to the overactivity of a cancer-promoting pathway called mTORC1. Increasing Fat Production: When mTORC1 is overactive, it boosts proteins that increase the production of fats. This results in cancer cells being flooded with fats, providing them with energy and materials needed to grow rapidly.   In short, this genetic player acts like a rogue conductor: it silences protective genes, promotes the cancer pathway and forces liver cells to overproduce fat —a perfect storm for cancer. A New Target for Liver Cancer Treatment These findings offer new hope for targeted therapies. One approach is to design drugs that block VPS72's interaction with H2A.Z proteins, potentially stopping the DNA changes that lead to cancer. Another strategy involves using existing drugs that inhibit mTORC1, a pathway already targeted in other cancers, which could be repurposed for liver cancer patients with increased VPS72 activity. By focusing on VPS72 and the pathways it affects, Professor Zhang’s team hopes to stop cancer from progressing. “Our research shows that the gene VPS72 plays two key roles in liver cancer (HCC): it affects both how genes are controlled and how fat metabolism goes wrong. The findings help explain how liver cancer develops and suggest new ways to treat cancers driven by abnormal fat metabolism,” said Professor Jiangwen Zhang, corresponding author of the study.  This research uncovers a critical link between genetic regulation, fat metabolism, and liver cancer. By targeting the genetic player VPS72 and its cancer-promoting pathway, scientists hope to open the door to more precise and effective treatments—potentially turning off a key fuel supply that liver tumours depend on. The full research paper can be accessed at:  https://advanced.onlinelibrary.wiley.com/doi/10.1002/advs.202411368   Figure 2. Professor Jiangwen ZHANG (second from the left) from HKU School of Biological Sciences and his research team.

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Artist’s impression of the nu Octantis system with the planet nu Oct Ab and the white dwarf nu Oct B around the primary subgiant star nu Oct A.Image generated by ChatGPT-4.0 and further modified by Trifon TRIFONOV using the GNU Image Manipulation Program.

HKU Astrophysicists Lead Research Team to Uncover the Role of Binary Star Evolution in the Origin of a Retrograde Planet

Most stars in the Universe exist in binary or multiple star systems, where the presence of close-in companion stars in such systems can adversely influence the formation and orbital stability of planets around one of the stars. An international team of astrophysicists led by Professor Man Hoi LEE from the Department of Earth Sciences and the Department of Physics at The University of Hong Kong (HKU) and Mr Ho Wan CHENG, an MPhil student in his team, has confirmed the existence of a planet in an unprecedented retrograde orbit (moving in the opposite direction to the binary’s orbit) in the nu Octantis binary star system and revealed the role of binary star evolution in the origin of this planet. The findings have been published in the journal Nature. nu Octantis is a tight binary star system comprising a primary subgiant star, nu Oct A, with about 1.6 times the mass of the Sun, and a secondary star, nu Oct B, with about half the mass of the Sun. The two stars orbit each other with a period of 1,050 days. An additional periodic signal in the radial velocity observations (measurements of how a star moves towards or away from us) of this system was first reported by Dr David RAMM, a co-author of this new paper, during his PhD studies at the University of Canterbury, New Zealand, in 2004. This signal was consistent with the presence of a Jovian planet of about twice the mass of Jupiter orbiting around the primary star, nu Oct A, with a period of about 400 days. However, the existence of this planet has been controversial because its orbit would be so wide that it could only remain stable if it were retrograde and moved in the opposite direction to the orbit of the binary. There were no observational precedents for such a planet and strong theoretical grounds against its formation. To settle the debate, the research team obtained new high-precision radial velocity observations using the European Southern Observatory (ESO)’s HARPS spectrograph, which confirmed the existence of the planet signal. ‘We performed an analysis of the new and archival radial velocity data spanning 18 years and found stable fits that require the planetary orbit to be retrograde and nearly in the same plane as the binary orbit,” said Mr Ho Wan CHENG, the first author of the paper. Another key focus of the new study was the determination of the nature of the secondary star nu Oct B. The mass of nu Oct B suggests that it could be either a low-mass main-sequence star or a white dwarf. All stars spend most of their lives on the main sequence, generating energy through nuclear fusion of hydrogen to helium in their core. After a star has exhausted its nuclear fuel, its core collapses into a stellar remnant, which would be a white dwarf if the star’s initial mass is less than several times that of the Sun. A white dwarf has a mass comparable to that of the Sun packed in an Earth-sized volume. To identify which type of star nu Oct B is, the research team used the adaptive optics imaging instrument SPHERE at ESO’s Very Large Telescope to observe the system. The fact that nu Oct B was not detected in these observations indicated that it must be a very faint white dwarf. This suggests that the binary system has evolved significantly since its formation, as nu Oct B has already ejected most of its mass and entered the final stage of its stellar evolution. The research team looked into the possible primordial configurations of the binary — that is, the initial masses of the two stars and the initial orbit of the binary. ‘We found that the system is about 2.9 billion years old and that nu Oct B was initially about 2.4 times the mass of the Sun and evolved to a white dwarf about 2 billion years ago,’ said Cheng. ‘Our analysis showed that the planet could not have formed around nu Oct A at the same time as the stars.’ The discovery that nu Oct B is a white dwarf opens new possibilities for how the retrograde planet may have originated. ‘When nu Oct B evolved into a white dwarf about 2 billion years ago, the planet could have formed in a retrograde disc of material around nu Oct A accreted from the mass ejected by nu Oct B, or it could be captured from a prograde orbit around the binary into a retrograde orbit around nu Oct A,’ explained Professor Man Hoi LEE. ‘We might be witnessing the first compelling case of a second-generation planet; either captured, or formed from material expelled by nu Oct B, which lost more than 75% of its primordial mass to become a white dwarf, ’ added Dr Trifon TRIFONOV of Zentrum für Astronomie der Universität Heidelberg in Germany and Sofia University St. Kliment Ohridski in Bulgaria and a co-author of the paper. ‘The key to this exciting discovery was the use of several complementary methods to characterise the system in its entirety,’ said PD Dr Sabine REFFERT of Zentrum für Astronomie der Universität Heidelberg and another co-author of the paper. As astronomers continue to search for planets in different environments, this study highlights that planets in tight binary systems with evolved stellar components could offer unique insights into the formation and evolution of planets. This research utilises two facilities operated by the European Southern Observatory (ESO), specifically the High Accuracy Radial Velocity Planet Searcher (HARPS) spectrograph at the ESO's 3.6-metre La Silla telescope and the Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE) instrument at the Very Large Telescope. Click here to view the video about the research.  For more details, please refer to the journal paper ‘A retrograde planet in a tight binary star system with a white dwarf’, published in Nature. 

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Beneath the waves, vibrant corals thrive alongside diverse marine life, a delicate ecosystem now being studied through eDNA to uncover the subtle impacts of human activities.Photo courtesy of Chuanqi Gong.

HKU Ecologists Unveil Critical Insights into Marine Biodiversity Dynamics Using Environmental DNA

A study led by the eDNA & eEcology lab at the School of Biological Sciences, The University of Hong Kong (HKU) has harnessed environmental DNA (eDNA) to decode the hidden impacts of human activities on marine biodiversity, offering new tools to monitor and combat ecosystem degradation. The study was led by Professor Mathew SEYMOUR, with key support from Ms Vivy Zhewei SI and collaboration with an international team of marine ecologists and geneticists, including Professor David BAKER, the interim Director of the Swire Institute of Marine Science (SWIMS). Their work underscores HKU’s leadership in marine conservation and its commitment to addressing global biodiversity challenges through innovative scientific approaches. The Silent Crisis in Our Oceans Marine biodiversity is under unprecedented threat from human activities, including coastal development, pollution, aquaculture, and overfishing. While the decline of coral reefs and fisheries has garnered global attention, our understanding of the broader impacts on marine ecosystems is still largely lacking. This is partially due to traditional monitoring methods, which rely on labour-intensive surveys and are often limited in their ability to capture the rapid and complex changes occurring in marine environments. To address this, Prof. Seymour’s team utilised eDNA metabarcoding, which offers relatively continuous, high-resolution snapshots of real-time dynamic changes in marine communities, revealing how human stressors disrupt ecosystems. A Race Against Time The study involved deploying 12 large-scale mesocosms (experimental tanks) seeded with Autonomous Reef Monitoring Structures (ARMS) that were previously colonised from natural reef habitats at SWIMS. Over a seven-month period, the team collected 240 eDNA water samples from the mesocosms to analyse three key eDNA and biological phases: 1) biodiversity accumulation, 2) response to human stressors, and 3) eDNA degradation. Species richness (i.e., the number of unique species) initially surged as ARMS were introduced into the mesocosms, stabilised during exposure to human stressors, and plummeted during the degradation phases after ARMS removal. During the response to human stressors phase, it found that aquaculture waste, particularly fish feed, significantly disrupted community composition, favouring groups like Gastropoda while suppressing algae. Significant changes in families such as Lithodesmiaceae (algae) and Haminoeidae (sea snails) highlight their potential as bioindicators under environmental stress. Additionally, the study highlighted variations in eDNA decay rates among species, with fish DNA degrading the fastest while algae and invertebrates persisted longer—a finding that could inform future monitoring strategies. Twelve large-scale mesocosms were involved in this study at HKU’s Swire Institute of Marine Science (SWIMS). Photo courtesy of Vivy Zhewei Si.   Bridging Gaps in Conservation Coral reefs, vital to marine biodiversity, are declining globally due to sedimentation and pollution. Yet, traditional surveys often miss cryptic species or fail to capture fine-scale changes. “eDNA allows us to see the invisible—tracking entire communities in real-time, not just individual species,” explained lead author Zhewei Si. “For the first time, we’ve quantified how stressors like fish feeding alter ecosystems at a molecular level.” While sedimentation and fertiliser treatments showed limited immediate impacts, the stark effects of fish feed underscore the need for stricter aquaculture regulations. “Even legal activities can destabilise ecosystems,” warned the team. “eDNA isn’t just a tool for science—it’s a lifeline for policymakers to act before species vanish.” “This study is just the beginning,” said Professor Seymour. “As we refine eDNA techniques, we’ll be able to improve local and regional monitoring of marine biodiversity, with extension to the global scale, providing the data needed to protect our oceans for generations to come.” Click here to learn more about the research.  Researchers:    Ms Vivy Zhewei SI   Professor Mathew SEYMOUR    

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Researchers Receive Environment and Conservation Fund to Drive Green Solutions

Our scientists have always been committed to advancing sustainable solutions. In the latest announcement of the Environment and Conservation Fund (ECF) of the HKSAR Government, the Faculty of Science has secured over HK$4.8 million under the ‘Research and Development Projects’ scheme. This achievement enables our researchers to further investigate and develop impactful strategies for environmental protection and conservation of natural resources. A summary of the approved funding is provided below: Projector Coordinator Department/School Project Title Approved Fund Project Duration Prof.  ASHTON Louise Amy Biological Sciences Environment and Conservation Fund Constructing the First DNA Barcode Reference Library of Hong Kong Moths HK$ 1,318,639 36 months Prof. BAKER David Michael Biological Sciences Environment and Conservation Fund Isotopic Methods for Protecting Incense Trees (Aquilaria sinensis) in Hong Kong SAR HK$ 1,513,280 36 months Prof. LEE Seungkyu Chemistry Environment and Conservation Fund Materials Development for Liquid Hydrogen Storage Systems with Reduced Boil-Off Rate HK$ 398,000 20 months Prof. SCHUNTER Celia Marei Biological Sciences Environment and Conservation Fund Unveiling the Hidden Threats in the Global Fish Maw Trade: A Baseline for Species Protection and Regulation HK$ 469,000 20 months Prof. HUGHES Alice Catherine Biological Sciences Environment and Conservation Fund for Species Identification of Ahermatypic Scleractinain Corals in Hong Kong Waters HK$ 486,000 18 months Prof. GAITÁN-ESPITIA Juan Diego Biological Sciences Environment and Conservation Fund Expansion Dynamics and Ecological Impacts of the Invasive Saltmarsh Spartina alterniflora in Hong Kong: Management Implications for Biodiversity and Ecosystem Functioning of Coastal Wetlands HK$ 659,200 24 months

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HKU Biologists Uncover How a Genetic Player Fuels Liver Cancer by Disrupting Fat Metabolism

Figure 1. Mechanism of how genetic player VPS72 impacts liver cancer. Too much VPS72 in cells activates the cancer-promoting pathway, which increases fat production and helps liver cancer grow. This study shows a new connection between fat buildup and liver cancer, suggesting new treatment possibilities. Image adapted from the respective paper at Advanced Science.   Liver cancer is a lethal disease with limited treatment options for advanced stages. While risk factors such as viral hepatitis, alcohol use, and obesity increase the likelihood of hepatocellular carcinoma (HCC, the progression of liver cancer), scientists are racing to uncover the hidden biological mechanisms that fuel tumour growth. Recent research led by Professor Jiangwen ZHANG of the School of Biological Sciences at The University of Hong Kong (HKU) has uncovered how a key genetic culprit, VPS72, drives the development of liver cancer by disrupting fat metabolism and manipulating gene activity. The team’s findings have been published in Advanced Science. The Fat-Liver Cancer Connection The liver is the body’s metabolic powerhouse, responsible for balancing fat production and breakdown. In healthy individuals, this process is tightly controlled. However, in HCC, liver cells accumulate excessive fat droplets, fuelling tumours to grow uncontrollably. This fat buildup is largely controlled by a key cellular pathway known as mTORC1, a molecular switch that activates fat-producing genes, and by SREBP proteins, which act as master regulators that directly control enzymes involved in fat synthesis. In cancer cells, mTORC1 becomes hyperactive, ramping up fat production and creating a vicious cycle that promotes tumour growth. The Role of Genetic Driver VPS72 in Liver Cancer Development Professor Zhang and his team discovered that VPS72, a gene that modifies how DNA is packaged inside cells, is overactive and abnormally amplified (i.e., present in extra copies) in over 50% of HCC patients. This amplification is linked to poorer survival rates, suggesting that this genetic player plays a central role in cancer progression. Here is how the mechanism works:   DNA Packaging: VPS72 helps attach specific proteins to DNA, which affects whether certain genes are turned on or off. Suppressing Protective Genes: VPS72 adds chemical tags to the promoter of gene ATF3, which normally helps prevent cancer growth. This tagging shuts down the production of ATF3, leading to the overactivity of a cancer-promoting pathway called mTORC1. Increasing Fat Production: When mTORC1 is overactive, it boosts proteins that increase the production of fats. This results in cancer cells being flooded with fats, providing them with energy and materials needed to grow rapidly.   In short, this genetic player acts like a rogue conductor: it silences protective genes, promotes the cancer pathway and forces liver cells to overproduce fat —a perfect storm for cancer. A New Target for Liver Cancer Treatment These findings offer new hope for targeted therapies. One approach is to design drugs that block VPS72's interaction with H2A.Z proteins, potentially stopping the DNA changes that lead to cancer. Another strategy involves using existing drugs that inhibit mTORC1, a pathway already targeted in other cancers, which could be repurposed for liver cancer patients with increased VPS72 activity. By focusing on VPS72 and the pathways it affects, Professor Zhang’s team hopes to stop cancer from progressing. “Our research shows that the gene VPS72 plays two key roles in liver cancer (HCC): it affects both how genes are controlled and how fat metabolism goes wrong. The findings help explain how liver cancer develops and suggest new ways to treat cancers driven by abnormal fat metabolism,” said Professor Jiangwen Zhang, corresponding author of the study.  This research uncovers a critical link between genetic regulation, fat metabolism, and liver cancer. By targeting the genetic player VPS72 and its cancer-promoting pathway, scientists hope to open the door to more precise and effective treatments—potentially turning off a key fuel supply that liver tumours depend on. The full research paper can be accessed at:  https://advanced.onlinelibrary.wiley.com/doi/10.1002/advs.202411368   Figure 2. Professor Jiangwen ZHANG (second from the left) from HKU School of Biological Sciences and his research team.

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Artist’s impression of the nu Octantis system with the planet nu Oct Ab and the white dwarf nu Oct B around the primary subgiant star nu Oct A.Image generated by ChatGPT-4.0 and further modified by Trifon TRIFONOV using the GNU Image Manipulation Program.

HKU Astrophysicists Lead Research Team to Uncover the Role of Binary Star Evolution in the Origin of a Retrograde Planet

Most stars in the Universe exist in binary or multiple star systems, where the presence of close-in companion stars in such systems can adversely influence the formation and orbital stability of planets around one of the stars. An international team of astrophysicists led by Professor Man Hoi LEE from the Department of Earth Sciences and the Department of Physics at The University of Hong Kong (HKU) and Mr Ho Wan CHENG, an MPhil student in his team, has confirmed the existence of a planet in an unprecedented retrograde orbit (moving in the opposite direction to the binary’s orbit) in the nu Octantis binary star system and revealed the role of binary star evolution in the origin of this planet. The findings have been published in the journal Nature. nu Octantis is a tight binary star system comprising a primary subgiant star, nu Oct A, with about 1.6 times the mass of the Sun, and a secondary star, nu Oct B, with about half the mass of the Sun. The two stars orbit each other with a period of 1,050 days. An additional periodic signal in the radial velocity observations (measurements of how a star moves towards or away from us) of this system was first reported by Dr David RAMM, a co-author of this new paper, during his PhD studies at the University of Canterbury, New Zealand, in 2004. This signal was consistent with the presence of a Jovian planet of about twice the mass of Jupiter orbiting around the primary star, nu Oct A, with a period of about 400 days. However, the existence of this planet has been controversial because its orbit would be so wide that it could only remain stable if it were retrograde and moved in the opposite direction to the orbit of the binary. There were no observational precedents for such a planet and strong theoretical grounds against its formation. To settle the debate, the research team obtained new high-precision radial velocity observations using the European Southern Observatory (ESO)’s HARPS spectrograph, which confirmed the existence of the planet signal. ‘We performed an analysis of the new and archival radial velocity data spanning 18 years and found stable fits that require the planetary orbit to be retrograde and nearly in the same plane as the binary orbit,” said Mr Ho Wan CHENG, the first author of the paper. Another key focus of the new study was the determination of the nature of the secondary star nu Oct B. The mass of nu Oct B suggests that it could be either a low-mass main-sequence star or a white dwarf. All stars spend most of their lives on the main sequence, generating energy through nuclear fusion of hydrogen to helium in their core. After a star has exhausted its nuclear fuel, its core collapses into a stellar remnant, which would be a white dwarf if the star’s initial mass is less than several times that of the Sun. A white dwarf has a mass comparable to that of the Sun packed in an Earth-sized volume. To identify which type of star nu Oct B is, the research team used the adaptive optics imaging instrument SPHERE at ESO’s Very Large Telescope to observe the system. The fact that nu Oct B was not detected in these observations indicated that it must be a very faint white dwarf. This suggests that the binary system has evolved significantly since its formation, as nu Oct B has already ejected most of its mass and entered the final stage of its stellar evolution. The research team looked into the possible primordial configurations of the binary — that is, the initial masses of the two stars and the initial orbit of the binary. ‘We found that the system is about 2.9 billion years old and that nu Oct B was initially about 2.4 times the mass of the Sun and evolved to a white dwarf about 2 billion years ago,’ said Cheng. ‘Our analysis showed that the planet could not have formed around nu Oct A at the same time as the stars.’ The discovery that nu Oct B is a white dwarf opens new possibilities for how the retrograde planet may have originated. ‘When nu Oct B evolved into a white dwarf about 2 billion years ago, the planet could have formed in a retrograde disc of material around nu Oct A accreted from the mass ejected by nu Oct B, or it could be captured from a prograde orbit around the binary into a retrograde orbit around nu Oct A,’ explained Professor Man Hoi LEE. ‘We might be witnessing the first compelling case of a second-generation planet; either captured, or formed from material expelled by nu Oct B, which lost more than 75% of its primordial mass to become a white dwarf, ’ added Dr Trifon TRIFONOV of Zentrum für Astronomie der Universität Heidelberg in Germany and Sofia University St. Kliment Ohridski in Bulgaria and a co-author of the paper. ‘The key to this exciting discovery was the use of several complementary methods to characterise the system in its entirety,’ said PD Dr Sabine REFFERT of Zentrum für Astronomie der Universität Heidelberg and another co-author of the paper. As astronomers continue to search for planets in different environments, this study highlights that planets in tight binary systems with evolved stellar components could offer unique insights into the formation and evolution of planets. This research utilises two facilities operated by the European Southern Observatory (ESO), specifically the High Accuracy Radial Velocity Planet Searcher (HARPS) spectrograph at the ESO's 3.6-metre La Silla telescope and the Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE) instrument at the Very Large Telescope. Click here to view the video about the research.  For more details, please refer to the journal paper ‘A retrograde planet in a tight binary star system with a white dwarf’, published in Nature. 

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Figure 1. Diagrammatic representation of the isostructural desymmetrisation strategy to transform an achiral catenane into a chiral structure.

HKU Chemists Develop Compact Catenane with Tuneable Mechanical Chirality, Offering New Possibilities for the Design and Application of Mechanically Interlocked Molecules

A team of chemists from The University of Hong Kong (HKU), in collaboration with international scientists, has made significant strides in the field of mechanically interlocked molecules (MIMs). Their work, recently published in the prestigious journal Nature Synthesis, showcases the development of a compact catenane with tuneable mechanical chirality, offering promising applications in areas such as material science, nanotechnology, and pharmaceuticals. The research was a collaborative effort led by the late Nobel Laureate Professor Fraser STODDART, alongside Research Assistant Professors Dr Chun TANG and Dr Ruihua ZHANG from HKU's Department of Chemistry. Contributions also came from researchers at HKU, Northwestern University and other global institutions. Catenanes and Mechanical Chirality Catenanes are unique molecular structures formed by the mechanical interlocking of two or more rings, akin to chain links. Unlike covalent bonds, these rings are held together by mechanical forces. Mechanical chirality refers to the chirality arising from the non-superimposable spatial arrangement of interlocked molecular rings, which can significantly impact their properties and functions. In this study, researchers demonstrated that two achiral rings with specific symmetrical features can create a catenane with mechanical chirality through an innovative isostructural desymmetrisation strategy. This allows the catenane to adopt a compact co-conformation, similar to its achiral counterpart. When interlocked in this compact form, the rings lose their individual symmetry and form chiral structures that cannot overlap with their mirror images, a property known as chirality in chemistry.  Technical Innovation and Methodology The research team has developed a catenane with tuneable chirality, achieved through chiral induction and advanced synthetic techniques. By introducing chiral disulfonate molecules, they can favour one mirror-image form over the other, allowing precise control over the catenane's behaviour in solutions and solid crystals. This tunability, driven by a compact design and strategic molecular geometry adjustments, suggests promising applications in smart materials, and nanotechnology and novel drug design. Computational modelling and experimental validation have enabled the manipulation of chirality by controlling the interaction and mechanical movements of the interlocked rings, allowing transitions between different chiral states. The researchers also revealed that the equilibrium between these enantiomers can be adjusted by introducing certain chiral molecules, inducing chirality and optical activity. Potential Applications In nanotechnology, these catenanes could be used to create molecular machines with specific chiral functionalities that perform tasks such as molecular recognition or targeted drug delivery. In materials science, the tunable properties of these structures could lead to the development of new materials and composites with customisable mechanical and optical characteristics for sensing and other applications. “The ability to create and control mechanical chirality in catenanes opens up new avenues for the development of advanced functional materials and artificial molecular machines,” said Dr Tang. “Our findings highlight the potential of using mechanical bonds to create chirality, which could have important implications for the field of chemistry and materials science.” The Research Team and Collaborators This research not only showcases the innovative capabilities of HKU's Department of Chemistry but also underscores the importance of international collaboration in advancing scientific knowledge. The study was supported by the University Research Committee of HKU, the US Department of Energy, and the Starry Night Science Fund of Zhejiang University Shanghai Institute for Advanced Study. This research is a collaboration among Professor Fraser Stoddart, Research Assistant Professors Chun TANG and Ruihua ZHANG from The University of Hong Kong, Professor Michael R WASIELEWSKI and Professor Evan A SCOTT from Northwestern University in the United States, and Professor Zhi Li from ShanghaiTech University. The international team also includes Drs. Han HAN, Guangcheng WU, and Yong WU, as well as Professor Aspen X-Y CHEN, Paige J BROWN, Ryan M YOUNG, Xueze ZHAO, Arthur H G DAVID, Bo SONG, Alexandre ABHERVE, Yu-Meng YE, Yuanning FENG, and Charlotte L STERN, all of whom made significant contributions to this research project. Professor Fraser STODDART passed away on December 30, 2024. At the time of submission, he was one of the corresponding authors. The journal paper “A Compact Catenane with Tuneable Mechanical Chirality” can be accessed from here: https://www.nature.com/articles/s44160-025-00781-z   The research group and their collaborators

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Figure 1. Diagram illustrating the use of noncoplanar building blocks to construct mesoporous HOFs with aromatic pore chemistry, achieving record-large 3.6 nm pores.

HKU Chemists Develop Breakthrough Material for Clean Energy Storage

A team of chemists at The University of Hong Kong (HKU) has made a breakthrough in materials chemistry that could change the way we store clean energy. Led by the late Nobel Laureate Professor Fraser Stoddart, the team developed RP-H200, a hydrogen-bonded organic framework (HOF) with the largest pores ever recorded in its category. This breakthrough could lead to advancements in clean energy storage, drug delivery, and environmental applications, and their research was recently published in the Journal of the American Chemical Society.   What Makes This Material Special? Creating large pores in molecular crystals without compromising their stability has always been difficult. The HKU team succeeded by developing RP-H200, a unique structure made from noncoplanar organic molecules held together by hydrogen bonds, similar to how Lego works. With pores measuring 3.6 nanometers and a surface area comparable to one-third of a football field per gram, this material is exceptional at storing gases like methane and hydrogen, opening doors to new sustainable technologies. How Was It Done? The team, including Dr. Ruihua Zhang and Dr. Chun Tang, used a new design to create RP-H200. They engineered the molecules to form a double-walled, honeycomb-like structure with aromatic surfaces that improve gas storage. At normal room temperature and pressure, RP-H200 can store more methane than many current materials. It is also very stable in heat, solvents, and humid conditions, making it useful for practical applications. Why Is This Important? The large pores in RP-H200 make it perfect for storing important fuels like methane and hydrogen, which are crucial for clean energy vehicles. It could also help in delivering drugs to specific areas of the body or capturing carbon dioxide to fight climate change. Its ability to be reused and processed easily adds to its potential for sustainable technology.  “This research demonstrates a viable pathway for constructing robust mesoporous molecular crystals with diverse pore chemistries, paving the avenue for future applications,” said Dr Zhang.  Who Was Involved? This milestone highlights the innovative prowess of HKU’s Department of Chemistry and the value of global collaboration. The study was supported by the University Research Committee of HKU, including the URC Seed Fund for Basic Research for New Staff 2024-25 (RIMS Project code: 2401102766).   The project involved an international team, including Professor Fraser Stoddart, Research Assistant Professors Ruihua Zhang and Chun Tang from HKU, Professor Shuliang Yang from Xiamen University, Professor Penghao Li from The University of Mississippi. Additional contributors included Drs. Han Han, Yong Wu, Guangcheng Wu, Xueze Zhao, Bai-Tong Liu, Sheng-Nan Lei, Bohan Tang, Enxu Liu, and Yi-Kang Xing from HKU, Professor Christos D. Malliakas and Charlotte L. Stern from Northwestern University, all of whom played vital roles. The journal article, titled “Double-Walled Mesoporous Hydrogen-Bonded Organic Frameworks with High Methane Storage Capacity,” is available at: https://doi.org/10.1021/jacs.5c02705.  

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