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This synthetic organism survives with less than 500 genes
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This week in Science, researchers led by genome sequencing pioneer Craig Venter report engineering a bacterium to have the smallest genome - and the fewest genes - of any freely living organism. Known as Syn 3.0, the new organism has a genome whittled down to the bare essentials needed to survive and reproduce, just 473 genes. However, the function of 149 of Syn 3.0's 473 genes remain unknown. As Syn 3.0's name suggests, it’s not the first synthetic life made by Venter. In 2010, Venter's team reported that they had synthesized the sole chromosome of Mycoplasma mycoides - a bacterium with a relatively small genome - and transplanted it into a separate mycoplasma called M. capricolum, from which they had previously extracted the DNA. After s ...
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10772 |
duddy |
8 years ago |
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4793 |
duddy |
7 years ago |
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An essential bone lost
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Despite slang terms that imply otherwise, the human penis contains no bones. The same cannot be said for many of our closest evolutionary relatives: Chimpanzees and bonobos both have penis bones (a macaque one is pictured, left), also known as bacula. To find out why some primates have the feature whereas others don’t, researchers traced the bone’s evolutionary history through time. The baculum first evolved between 145 million and 95 million years ago, as reported in the Proceedings of the Royal Society B. That means it was present in the most recent common ancestor of all primates and carnivores. Why some descendants, like humans, lost their bacula appears to be due to differences in mating practices: In primates, the presence of a penis ...
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16664 |
duddy |
7 years ago |
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What causes the rattle in a rattlesnake's tail?
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Rattlesnakes are a group of venomous snakes native to the Americas known for their loud rattling tail. The tip of their tail, known as the rattle (middle), vibrates to deter predators or serves as a warning to passers-by. The rattle is composed of a series of hollow, interlocked segments made of keratin, which are created by modifying the scales that cover the tip of the tail. The contraction of special "shaker" muscles in the tail causes these segments to vibrate against one another, making the rattling noise (which is amplified because the segments are hollow) in a behavior known as tail vibration. The muscles that cause the rattle to shake are some of the fastest known, firing 50 times per second on average, sustained for up to three hour ...
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5983 |
bio_man |
6 years ago |
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Poison dart frog
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The poison dart frog is the common name given to the most poisonous animals on Earth. Native to Central and South America, these species of frogs (family: Dendrobatidae) produce several lethal toxins that are capable of killing a human or other large animal with just 2 micrograms (μg). In other words, one drop of their venom could be powerful enough to kill 8000 people. The most toxic of poison dart frog species is Phyllobates terribilis. Unlike snakes, dart frogs do not synthesize their poisons, but sequester the chemicals they consume from arthropod prey, such as ants, centipedes and mites. This is why in captivity, they produce far less poison than wild frogs due to their change in diet. What makes these frogs immune to their own poison i ...
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1503 |
bio_man |
5 years ago |
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Key energy-producing proteins missing in this plant
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To produce cellular energy, nearly all multicellular organisms use a series of highly specialized proteins embedded in the inner member of the mitochondria to transport and pump electrons, collectively known as the electron transport chain. A new study has revealed that this is not the case in European mistletoes, the traditional Christmas ornament hung to give someone a kiss underneath it. After sequencing the organism's genome, researchers couldn't find any mitochondrial genes for coding the protein subunits that make up the electron transport chain’s first station, called complex I. To find out which parts of the assembly line machinery had disappeared, researchers extracted proteins from mitochondria in the mistletoe's leaves and compar ...
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1478 |
bio_man |
5 years ago |
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Where is our third eyelid?
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Some mammals, such as camels, polar bears, and seals, have full nictitating membranes. That is the transparent or translucent third eyelid that can be drawn across the eye for protection and to moisten it while maintaining visibility. In humans, the plica semilunaris (also known as the semilunar fold) and its associated muscles are thought to be homologous to the nictitating membranes seen in other animals. In most primate species, a plica semilunaris is present, but a fully developed nictitating membranes still exists in lemurs and lorisiform primates. Unlike the upper and lower eyelids, the nictitating membrane moves horizontally across the eyeball (shown below). In some diving animals, such as beavers and manatees, it moves across the e ...
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2578 |
bio_man |
4 years ago |
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Simulating the evolution of aggression
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This video brings to life the evolution of aggresive behavior in a population, and its relation to game theory – the field of mathematics concerned with quantifying strategic behavior and decision-making. The author illustrates what happens in an artificial population of species that exhibit two entirely different strategies as they compete for resources. In the first strategy called ‘dove’, organisms are required to share their food source with the other if both happen to land at the same site after being randomly shuffled. Sharing your food source allows the organism to survive another cycle, but not reproduce, unless they’re fortunate enough to land at a site all by them self. The author shows that if this cooperative strategy is ...
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3678 |
duddy |
2 years ago |
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