ريتشارد دوكنز's Blog, page 774
February 23, 2015
Bacteria Got Early Fix on Nitrogen
Oxygen and water are crucial to most life on Earth, but what about nitrogen? It’s in every molecule of DNA in your body, and in all your proteins—you literally can’t live without it. But most of Earth’s nitrogen exists as an inert atmospheric gas that organisms can’t use.
Lightning strikes can convert some nitrogen into a bioavailable form. But most of the biosphere’s usable nitrogen is the result of bacteria employing an enzyme called nitrogenase to pull nitrogen out of the air.
Based on genetic evidence, scientists have thought that nitrogenase first evolved around 2 billion years ago. Before that, life on Earth might have been confined to the oceans and been limited by the crucial substance’s inaccessibility.
But researchers at the University of Washington now have evidence for the existence of nitrogenase in bacteria going back some 3.2 billion years. The researchers base their argument on the ratios of light-to-heavy nitrogen isotopes in ancient rocks from Australia. The study is in the journal Nature. [Eva E. Stüeken et al, Isotopic evidence for biological nitrogen fixation by molybdenum-nitrogenase from 3.2 Gyr]
The finding indicates that the biosphere more than three billion years ago was much more complex than previously appreciated, and perhaps had already colonized land. An earlier arrival for nitrogenase also may mean that the enzyme evolves more easily than was previously believed. Which could increase the odds that, sooner or later, astrobiologists will find signs of another robust biosphere on some world far away.
—Lee Billings
(The above text is a transcript of this podcast)
Scientific American is part of the Nature Publishing Group
Why Do Koalas Hug Trees?
As if koalas could be any more adorable, they also tend to spend a lot of their time hugging trees. But why? Quick Questions has the answer!
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Sources:
http://rsbl.royalsocietypublishing.org/content/10/6/20140235
http://www.theguardian.com/environment/2014/jun/04/koalas-have-learned-a-new-trick-to-beat-the-heat-scientists-say
http://www.wired.com/2014/06/science-graphic-of-the-week-adorable-chart-shows-why-koalas-hug-trees/
http://www.australiangeographic.com.au/news/2014/06/koalas-hug-trees-to-keep-cool
Briscoe NJ, Handasyde KA, Griffiths SR, Porter WP, Krockenberger A, Kearney MR. Tree-hugging koalas demonstrate a novel thermoregulatory mechanism for arboreal mammals. Biology Letters 2014; 10. Doi: 10.1098/rsbl.2014.0235
February 22, 2015
Cheap Solar Cells Made From Shrimp Cells
Photo credit:
Queen Mary University of London
Compounds found in the shells of shrimp and other tasty crustaceans have been used to generate electricity in solar cells for the first time.
Crustacean exoskeletons get their structure from a sugary compound called chitin. Chitin and its derivative, chitosan, are much cheaper and more abundant than expensive metals like ruthenium (similar to platinum) that are used to make nanostructured solar cells now.
The History of Philosophy and Suicide
February 21, 2015
Genes Connected to Autism Active During Fetal Development
Photo credit:
vetre/Shutterstock
Autism Spectrum Disorder (ASD) affects about 1 in 68 children. Genetics plays a large role in the onset of ASD, but the exact genes involved are not clearly defined. However, a new paper published in Neuron describes how specific genes known to be connected to ASD are active during fetal brain development. Lilia Iakoucheva of the University of California, San Diego headed up the research.
Black Hole Winds Might Regulate Size of Galaxy
Photo credit:
NASA/JPL-Caltech
Supermassive black holes still hold a great deal of mystery. While they are commonly regarded as giant entities that gobble up all matter that comes too close, it has also been presumed that they kick out a considerable amount of x-ray wind, as well. The presence of this wind has been confirmed for the first time, and astronomers have even been able to decipher the shape of the wind. This discovery was made by the respective groups working for NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and and ESA’s XMM-Newton telescope.
New Brain Map Reveals Unknown Cell Types
MAVEN Spacecraft Takes First Deep Dip
Photo credit:
NASA's Goddard Space Flight Center
NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft arrived at the Red Planet back in September. Its mission is to analyze the martian atmosphere in hopes of learning more about what had happened to it, and why Mars is no longer able to sustain liquid water on the surface. Part of this year-long mission will include five low dips toward the planet’s surface in order to study the lower aspects of the upper atmosphere.
MICHIGAN SUCKS BALLS
Homophobic pediatrician and anti-gay laws in Michigan. ‘Murka.
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Stinky Caterpillar Looks Like a Snake With a Fleshy, Forked Tongue
Photo credit:
The Eastern Tiger Swallowtail (Papilio glaucus) caterpillar with fully everted osmeterium is pictured from Bradford County, Florida / Edith Smith (Shady Oak Butterfly Farm)
Eastern tiger swallowtails, as their name suggests, have vivid orange and black stripes. These showy butterflies are so popular in the eastern U.S., they’re the state insect of five states. But their caterpillars, on the other hand, are fierce-looking stinkers. They’re disguised as stubby snakes with a big, fake green head, markings that look like black and yellow eyes, and (the best part) a forked, fleshy orange tongue.
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