Researchers have solved a 60-year genetic mystery by pinpointing the change that makes cats orange: a ~5 kilobase deletion in a non-protein-coding region upstream of the gene Arhgap36. Skin cells that produce orange fur show about 13 times more Arhgap36 RNA than non-orange cells, and the deletion was found in every orange cat in a 188-cat dataset (145 orange, 6 calico/tortoiseshell, 37 non-orange). Two independent teams, led by Greg Barsh and Hidehiro Toh, showed that increased Arhgap36 expression in melanocytes suppresses genes for dark eumelanin and shifts pigment production toward reddish-yellow pheomelanin, explaining the fiery hues.
Because the mutation sits on the X chromosome, inheritance follows classic sex-linked patterns: males with the mutant X are uniformly orange, while females with one mutant and one normal X become mosaics due to random X inactivation, producing tortoiseshell or, with an additional white-spotting mutation that limits melanocyte survival, calico patterns. The change appears localized to pigment cells with no clear adverse health or cognitive effects reported. The work, published in Current Biology, reconciles long-observed coat-color patterns with a concrete genomic mechanism.
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A 1,000-mile-long cloud forms and disappears daily on Mars, exhibiting exotic physics not seen on Earth. This phenomenon provides new insights into Martian atmospheric processes. (livescience.com)
Stochastic solar mass loss can lead to the terminal instability of the solar system, potentially causing its eventual disintegration. Researchers suggest that random variations in the Sun's mass may trigger long-term dynamical chaos among the planets. (iopscience.iop.org)
Mary Tsingou, a mathematician, waited 50 years to receive proper recognition for her work on the Manhattan Project. She passed away before her contributions were fully acknowledged, highlighting the long delay in crediting her achievements. (nytimes.com)
Navier-Stokes equations are fundamental in fluid dynamics and describe the motion of viscous fluids. Vi Hart's post explores their mathematical properties and significance in understanding fluid behavior. (patreon.com)
Swordfish washing up on British Columbia's coast indicates changes in ocean conditions and ecosystems. Scientists study these events to understand broader impacts of climate change on marine life. (phys.org)
Delegates will soon vote on whether to eliminate the leap second, which has been added irregularly to keep atomic clocks aligned with Earth's rotation. If approved, a leap hour could be observed in the distant future to replace the leap second. (abc.net.au)
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