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Agriculture and Food

Hovering Fish Burn Twice the Energy – Study Shocks Scientists

Hovering fish aren’t loafing—they burn twice resting energy to make micro-fin tweaks that counteract a natural tendency to tip, and body shape dictates just how costly the pause is. The discovery flips a long-held assumption about effortless neutral buoyancy and offers fresh blueprints for agile, instability-embracing underwater robots.

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“Fish make hanging motionless in the water column look effortless, and scientists had long assumed that this meant it was a type of rest,” begins the article. However, a new study reveals that fish use nearly twice as much energy when hovering in place compared to resting.

The study, led by scientists at the University of California San Diego’s Scripps Institution of Oceanography, also details the biomechanics of fish hovering, which includes constant, subtle fin movements to prevent tipping, drifting or rolling. This more robust understanding of how fish actively maintain their position could inform the design of underwater robots or drones facing similar challenges.

The findings, published on July 7 in the Proceedings of the National Academy of Sciences, overturn the long-standing assumption in the scientific literature that maintaining a stationary position in water is virtually effortless for fish with swim bladders. The reason for this assumption was that nearly all bony fishes have gas-filled sacs called swim bladders that allow them to achieve neutral buoyancy — neither sinking nor rising to the surface. The presence of a swim bladder and the stillness of hovering fish caused the research community to assume hovering was a form of rest that was easy for fish to maintain.

Prior research from lead study author and Scripps marine biologist Valentina Di Santo found that the energy required for skates to swim at various speeds followed a distinct U-shaped curve, with slow and fast swimming requiring the most energy and intermediate speeds being the most energy-efficient. Based on these findings, Di Santo suspected there might be more to hovering than meets the eye.

To learn more, Di Santo and her co-authors conducted experiments with 13 species of fishes with swim bladders. The team placed each fish in a specialized tank and recorded their oxygen consumption during active hovering and motionless resting (when the fish supports its weight with the bottom of the tank). While the fish were hovering, the researchers filmed them with high-speed cameras to capture their fin movements, tracking how each fin moved and how frequently they beat.

The researchers also took a variety of measurements of each fish’s body size and shape. In particular, the scientists measured the physical separation between the fish’s center of mass, which is determined by weight distribution, and its center of buoyancy, which is related to the shape and location of its swim bladder. All these measurements provided a way to quantify how stable or unstable each fish was.

The study found that, contrary to previous assumptions, hovering burns roughly twice as much energy as resting. “Hovering is a bit like trying to balance on a bicycle that’s not moving,” said Di Santo.

Despite having swim bladders that make them nearly weightless, fish are inherently unstable because their center of mass and center of buoyancy don’t align perfectly. This separation creates a tendency to tip and roll, forcing fish to make continuous adjustments with their fins to maintain position. The study found that species with greater separation between their centers of mass and buoyancy used more energy when hovering. This suggests that counteracting instability is one of the factors driving the energy expended during hovering.

“What struck me was how superbly all these fishes maintain a stable posture, despite their intrinsic instability,” said Di Santo.

A fish’s shape and the position of its pectoral fins also influenced its hovering efficiency. Fish with pectoral fins farther back on their body were generally able to burn less energy while hovering, which Di Santo suggested may be due to improved leverage. Long, slender fish, such as the shell dweller cichlid (Lamprologus ocellatus) and the angelfish (Pterophyllum scalare), were found to be less efficient hoverers compared to more compact species like the guppy (Poecilia reticulata) and the zebrafish (Danio rerio).

The study’s findings have significant implications for the design of underwater robots. “By studying how fish achieve this balance, we can gain powerful design principles for building more efficient, responsive underwater technologies,” said Di Santo.

In particular, the findings could help improve the maneuverability of underwater robots, which could allow them to access and explore complex, hard-to-navigate environments like coral reefs or shipwrecks. According to Di Santo, underwater robots have historically been designed with compact shapes that make them stable. As in fish, shapes with more built-in stability are less maneuverable.

“If you want a robot that can maneuver through tight spaces, you might have to learn from these fishes to design in some instability and then add systems that can dynamically maintain stability when needed,” said Di Santo.

The study was co-authored by Xuewei Qi of Stockholm University, Fidji Berio of Scripps Oceanography, Angela Albi of Stockholm University, the Max Planck Institute of Animal Behavior, and the University of Konstanz, and Otar Akanyeti of Aberystwyth University in Wales. The research was supported by the Swedish Research Council, the European Commission, the Stockholm University Brain Imaging Centre and the Whitman Scientist Program at the Marine Biological Laboratory.

Agriculture and Food

Unearthing Life’s Secrets: Deep Microbes Thrive without Sunlight

Chinese scientists uncovered a powerful energy source for deep Earth microbes: hydrogen and oxidants generated by rock fracturing during earthquakes. The process may also suggest how life could exist on other planets without sunlight.

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The discovery that life can exist and even flourish in environments devoid of sunlight has long been a topic of fascination for scientists. A recent study published in Science Advances by Chinese researchers has shed new light on this phenomenon, revealing how microbes in deep subsurface areas derive energy from chemical reactions driven by crustal faulting. This groundbreaking research challenges the conventional wisdom that “all life depends on sunlight” and offers critical insights into the existence of life deep below Earth’s surface.

Led by Professors Hongping He and Jianxi Zhu from the Guangzhou Institute of Geochemistry, a team of researchers simulated crustal faulting activities to understand how free radicals produced during rock fracturing can decompose water, generating hydrogen and oxidants like hydrogen peroxide. These substances create a distinct redox gradient within fracture systems, which can further react with iron in groundwater and rocks – oxidizing ferrous iron (Fe²⁺) to ferric iron (Fe³⁺) or reducing ferric iron (Fe³⁺) to ferrous iron (Fe²⁺), depending on local redox conditions.

In microbe-rich fractures, the researchers found that hydrogen production driven by earthquake-related faulting was up to 100,000 times greater than that from other known pathways, such as serpentinization and radiolysis. This process effectively drives iron’s redox cycle, influencing geochemical processes of elements like carbon, nitrogen, and sulfur – sustaining microbial metabolism in the deep biosphere.

This study has far-reaching implications for our understanding of life on Earth and beyond. Professors He and Zhu note that fracture systems on other Earth-like planets could potentially provide habitable conditions for extraterrestrial life, offering a new avenue for the search for life beyond Earth. The research was financially supported by various sources, including the National Science Fund for Distinguished Young Scholars and the Strategic Priority Research Program of CAS.

In conclusion, this groundbreaking study has challenged our understanding of life’s dependence on sunlight and revealed a previously unknown source of energy for microbes in deep subsurface areas. As we continue to explore the mysteries of the deep biosphere, we may uncover even more secrets that will rewrite the textbooks on life on Earth and beyond.

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Agriculture and Food

Breaking New Ground: Scientists Develop Groundbreaking Chromosome Editing Technology

A group of Chinese scientists has created powerful new tools that allow them to edit large chunks of DNA with incredible accuracy—and without leaving any trace. Using a mix of advanced protein design, AI, and clever genetic tweaks, they’ve overcome major limitations in older gene editing methods. These tools can flip, remove, or insert massive pieces of genetic code in both plants and animals. To prove it works, they engineered rice that’s resistant to herbicides by flipping a huge section of its DNA—something that was nearly impossible before.

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The field of genetic engineering has taken a significant leap forward with the development of two new genome editing technologies by a team of Chinese researchers led by Prof. Gao Caixia from the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences. These innovations, collectively known as Programmable Chromosome Engineering (PCE) systems, have been published in the prestigious journal Cell.

The PCE system is an upgrade to the well-known Cre-Lox technology, which has long been used for precise chromosomal manipulation. However, this older method had three major limitations that hindered its broader application: low recombination efficiency, reversible recombination activity, and the need for a scar (a small DNA fragment) at the editing site.

The research team tackled each of these challenges by developing novel methods to advance the state of this technology. Firstly, they created a high-throughput platform for rapid recombination site modification and proposed an asymmetric Lox site design that reduces reversible recombination activity by over 10-fold.

Secondly, they utilized their recently developed AiCE model – a protein-directed evolution system integrating general inverse folding models with structural and evolutionary constraints – to develop AiCErec. This approach enabled precise optimization of Cre’s multimerization interface, resulting in an engineered variant with a recombination efficiency 3.5 times that of the wild-type Cre.

Lastly, they designed and refined a scarless editing strategy for recombinases by harnessing the high editing efficiency of prime editors to develop Re-pegRNA, a method that uses specifically designed pegRNAs to perform re-prime editing on residual Lox sites, precisely replacing them with the original genomic sequence.

The integration of these three innovations led to the creation of two programmable platforms, PCE and RePCE. These platforms allow flexible programming of insertion positions and orientations for different Lox sites, enabling precise, scarless manipulation of DNA fragments ranging from kilobase to megabase scale in both plant and animal cells.

Key achievements include targeted integration of large DNA fragments up to 18.8 kb, complete replacement of 5-kb DNA sequences, chromosomal inversions spanning 12 Mb, chromosomal deletions of 4 Mb, and whole-chromosome translocations. As a proof of concept, the researchers used this technology to create herbicide-resistant rice germplasm with a 315-kb precise inversion.

This groundbreaking work not only overcomes the historical limitations of the Cre-Lox system but also opens new avenues for precise genome engineering in various organisms, demonstrating its transformative potential for genetic engineering and crop improvement.

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Agriculture and Food

The Ancient Origins of Potatoes Revealed

About 9 million years ago, a wild interspecies fling between tomato-like plants and potato relatives in South America gave rise to one of the world’s most important crops: the potato. Scientists have now traced its roots to a rare natural hybridization that created the tuber, a storage organ that allowed the plant to survive harsh Andean environments and spread rapidly.

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The mystery of where potatoes came from has been solved by an international research team. Scientists have uncovered that 9 million years ago, a natural interbreeding event occurred between tomato plants and potato-like species from South America, giving rise to the modern-day potato. This ancient evolutionary event triggered the formation of the tuber, the enlarged underground structure that stores nutrients in plants like potatoes, yams, and taros.

The research team analyzed 450 genomes from cultivated potatoes and 56 wild potato species to solve this long-standing mystery. They found that every potato species contained a stable mix of genetic material from both Etuberosum and tomato plants, suggesting an ancient hybridization between the two. The team also traced the origins of the potato’s key tuber-forming genes, which are a combination of genetic material from each parent.

The discovery reveals how a hybridization event can spark the evolution of new traits, allowing even more species to emerge. This is particularly significant in the context of one of the world’s most important crops, the potato. As one of the world’s most widely cultivated foods, potatoes have long puzzled scientists with their seemingly identical appearance to Etuberosum plants but lack of tubers.

To fill this knowledge gap, researchers analyzed 450 genomes from cultivated potatoes and 56 wild potato species. They found that every potato species contained a stable mix of genetic material from both Etuberosum and tomato plants. This suggests an ancient hybridization event occurred between the two, which gave rise to the modern-day potato.

The team’s findings also reveal how this ancient evolutionary innovation coincided with the rapid uplift of the Andes mountains. As new ecological environments emerged, early potatoes were able to quickly adapt and survive in harsh weather conditions using their tubers as a nutrient storage system. This allowed them to rapidly expand and fill diverse ecological niches from mild grasslands to high and cold alpine meadows in Central and South America.

The discovery of the potato’s ancient origins is a significant breakthrough in understanding how new species emerge. It highlights the importance of natural interbreeding events in shaping the evolution of plants and their adaptation to changing environments.

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