Unveiling Scientific Discoveries: From Glowing Humans to Star Lifespans
This week's science news covers fascinating topics, including the discovery of human bioluminescence, the genetic basis of orange cats, the composition of a young star system, a new Alzheimer's treatment direction, and gene editing for a rare disease. Let's dive into the details.
The Secret of Human Bioluminescence
It turns out that humans, along with all living things, emit a faint light. A research team at the University of Calgary discovered that all life forms they tested, including plants and animals, emit light, a phenomenon called Ultraweak Photon Emission (UPE).
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The emitted light's wavelength ranges from ultraviolet to near-infrared, including the visible light spectrum.
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However, the light is very weak, emitting only about 10 to 1000 photons per square centimeter per second, making it almost invisible to the naked eye.
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Scientists captured this light using highly sensitive cameras and found that dead mice emitted less UPE than living mice, even when controlling for temperature.
The researchers believe this light emission is due to the production of reactive oxygen species (ROS) during metabolic reactions. ROS are highly reactive and can cause oxidation reactions in cells, leading to electron excitation. When these excited electrons return to a stable state, they release energy in the form of photons. Furthermore, in plants, UPE intensity increases when exposed to stress, such as high temperatures or chemical substances. Scientists suggest this discovery could lead to new non-invasive methods for monitoring life.
The Mystery of the Orange Cat's Gender
Why are most orange cats male? Scientists have finally cracked the code. Two independent research teams from Kyushu University in Japan and Stanford University in the United States published studies in Current Biology, both pointing to a gene called ARHGAP36 in cat DNA.
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A deletion of about 5.1 kilobases (kb) in the ARHGAP36 gene inhibits its activity.
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This results in a higher expression level, causing hair follicle cells to produce pheomelanin (orange/yellow pigment) instead of eumelanin (black/brown pigment).
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The ARHGAP36 gene is located on the X chromosome.
Male cats with a deletion on their X chromosome will always be orange. Female cats have two X chromosomes, and during development, each cell randomly deactivates one X chromosome. Therefore, if one X chromosome has the deletion and the other doesn't, the coat will be a mix of black and orange, which explain why tortoiseshell or calico cats are almost always female.
Webb Telescope Uncovers "Crystalline" Water Ice
The James Webb Space Telescope has made another groundbreaking discovery: crystalline water ice around the young star system HD 181327, located approximately 155 light-years from Earth.
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Unlike the amorphous ice found in typical freezer, this ice has an ordered structure.
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The formation of crystalline water ice requires specific temperature and energy conditions.
This suggests that the young planetary system was once warmer, allowing for the formation of crystalline ice. The dust disk structure of HD 181327, only 23 million years old, resembles our solar system's Kuiper Belt during its early stages. Studying it can help us understand the origin of water on Earth. Webb Telescope's observations also show frequent collisions in the dust disk, releasing water ice-rich particles detected by the telescope. Scientists estimate the water ice content in the system's outer disk to be over 20%.
A Gene Linked to Alzheimer's Disease
Taiwanese scientists have identified a gene, CLEC5A, that may play a significant role in Alzheimer's disease, potentially opening new avenues for treatment. Researchers from Yang Ming Chiao Tung University and the National Health Research Institutes published their findings in the Journal of Neuroinflammation.
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CLEC5A is known to be activated during viral infections, such as dengue fever and COVID-19, triggering an immune response.
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However, in Alzheimer's disease, excessive CLEC5A activity hinders the brain's cleaning crew, the microglia.
Microglia are responsible for removing brain waste like beta-amyloid plaques. However, overactivated CLEC5A puts microglia into a state of inactivity. This results in the accumulation of brain waste, potentially leading to chronic neuroinflammation and cognitive impairment. To test this, scientists genetically deleted CLEC5A in mice with Alzheimer's disease. The mice without CLEC5A showed improved memory and learning performance compared to those with the gene active. Additionally, they had significantly fewer beta-amyloid deposits in their brains.
Gene Editing for a Rare Disease
In a groundbreaking case, a baby named KJ with a rare genetic disorder called carnitine acylcarnitine translocase deficiency (CACT deficiency) received a personalized CRISPR gene editing therapy and showed positive results. This condition prevents the body from converting toxic ammonia into urea for excretion, leading to severe symptoms and potential brain or liver damage.
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Traditional treatment options are limited, with liver transplantation being a high-risk procedure, especially for infants.
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Scientists developed a personalized CRISPR gene editing therapy for KJ within six months, from diagnosis to treatment.
The therapy involved a direct, in vivo gene editing approach using base editing technology to correct the faulty CPS1 gene in KJ's liver cells. The gene editing tool was delivered via lipid nanoparticles through intravenous injection, without removing cells from the body for manipulation. As of April, KJ had received three doses without significant side effects. He has shown improved tolerance to protein and requires less medication. The gene editing is designed to target somatic cells only and will not be passed on to future generations.
Death of Stars
Astronomers have drastically shortened the estimated lifespans of white dwarf stars. Physicist Heino Falcke and colleagues recently published a new theory in JCAP, estimating white dwarf lifespans at approximately 10^78 years, drastically shorter than previous estimates of 10^1100 years. This new theory is not a doomsday forecast, but a new perspective on theoretical stellar decay.
According to the new model: The quantum vacuum is not empty, but is full of electromagnetic fields, electron fields and energy. It is from here that "virtual pairs" of subatomic particles are temporarily born from the borrowing of a bit of energy from these fields, then quickly disappear. These fields are greatly affected by the gravity of a very dense celestial body, like a white dwarf or a neutron star, and the strong gravitational force bends space-time.
This new theory suggests that the powerful gravity of such objects could separate some of these particle pairs before they can rejoin and return the borrowed energy, effectively creating real particles and leading to mass loss and eventual decay. As celestial bodies become denser, the rate of "evaporation" increases.
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