FEATURED IMAGE: Strange alignment of two distant galaxies
This image, taken by the Hubble telescope, shows two galaxies, NGC 3314A and NGC 3314B, which appear to be crashing into each other. The blue galaxy in the foreground (facing the viewer) is ~ 117 million light-years away from Earth, while the background galaxy is 23 million light-years farther away. Galaxies have crashed into each other occasionally, and our own Milky Way galaxy will hit the neighboring Andromeda galaxy 4 billion years in the future.
And while we are on the subject of telescopes, a new, privately built X ray telescope has been launched into orbit from an airplane! Good news, private space exploration is actually happening. Our technology fan, Michel, reports:
Privately designed, built and launched, this school bus-length X-ra... is put in orbit from an airplane! This past week the NuSTAR X-ray observatory was successfully put in orbit with a Pegasus rocket launched from a modified L-1011 airliner. This is amazing on many levels: 1- The project was designed and executed in the private sector. Orbital Sciences designed, manufactured, integrated and tested the Nuclear Spectroscopic Telescope Array (NuSTAR) scientific satellite under a contract from the California Institute of Technology and the Jet Propulsion Laboratory; 2- The satellite was launched using a Pegasus rocket, a smaller vehicle that is literally dropped from an airplane and blasts away into space. This method saves a huge amount of fuel by starting the rocket a few kilometers above the ground; 3- X-ray observatories like Chandra, XMM-Newton, and NuSTAR require very long cylindrical mirrors to focus the high energy photons. However, to fit on the diminutive Pegasus rocket, NuSTAR has to be only 2 meters long. Engineers solved this length problem in a very cool way: an extendable boom, like an accordion, that expands after launch and lengthens the spacecraft to over 10 meters! At one end of the extended mast are the mirrors, and at the other end are the detectors; and 4- When the instrument is turned on it will be the first focusing high energy X-ray satellite in orbit, providing more than two orders of magnitude improvement in sensitivity as compared to previous high energy missions. The primary science goals of NuSTAR are broad, and include: conducting a survey of black holes, mapping young supernovae explosions, studying nature's most powerful cosmic accelerators, identifying high energy sources in our Galaxy and studying the Sun's coronal mass ejections.
This week I feel like starting the biology portion of the Fix with rodents. Rodents are the mammalian group that contains the most species. They range from the lowly but ubiquitous mouse, to the huge capybara (a favorite of doone’s, and a native species to my birthplace, Uruguay). And because Father’s Day is coming up, let’s start with a beautiful story regarding an exemplary father with very big, continuously growing teeth. I did not come up with the title, but I wish I did:
Single parent beaver dad gives a dam. I had no idea that beavers mate for life, and that beaver fathers are among the best in the animal kingdom. This story is about a beaver dad who lost his long time mate to a deadly infection. The couple had successful raised 12 kits previously, in a colony in Martinez, California. The poor male was left all alone with three very young kits. Beaver dad duties include building new dams, repairing the existing home, and gathering food. Researchers worried that this beaver dad would not be able to raise the three babies by himself. But not fazed by the circumstances, beaver dad kept up with all his tasks and somehow managed to teach the young ones how to dive. He even selected tender shoots to feed his offspring. In addition to tackling care-giving basics, he gave the kits beaver-back rides and taught them how to dive. He brought them gourmet tender new shoots for dinner. All three kits survived to adulthood and still live with their dad. Beavers usually leave the home where they grew up by 2-3 years of age.
To see a bunch of pictures from the world’s most devoted animal dads, see here. The dedicated fathers include marmosets, bat-eared foxes, penguins, ostriches, and even frogs and waterbugs!
Beavers and capybaras are big and astonishing, but perhaps the most radical rodent out there is the naked mole rat.
Naked mole rats as supermodel organism. The cute-but-ugly little beasties made the cover of The Scientist. The main article features loads of fascinating information about these creatures, and how they can help us understand cancer, pain, and aging. These underground rodents are as big as a mouse, yet like 10 times longer than mice; unlike mice, they never get cancer and they have a high tolerance for pain and toxins. These unusual features made them an ideal model to study a whole variety of biological processes. If we understand what makes them so tough and long-lived, we could be closer to understanding how to deal with cancer and aging. And for those of you who think their secret is that they live in groups with a queen who mates with multiple males, until her old age, well, that's not the secret to their long, healthy life. The naked mole rat genome has just been sequenced and some clues have emerged: they repair DNA unusually well, and they control cell proliferation very tightly; they are very good at cleaning up cells from misfolded proteins, and they are very good at detoxifying. Please read the whole article to get all the details; they are fascinating creatures. Plus one of the authors of the article is a good friend of mine; I have been lucky enough to visit her stupendous naked mole rat colony and I have seen and touched the little beauties.
We cannot have a Science Fix without highlighting the wonder of adaptations and of co-evolution. Next we will see how a plant forces a little desert mouse to spit out its seeds instead of eating them
Plant uses chemical weapons to make mice spit out its seeds. Seeds are highly nutritious so it’s no surprise that rodents really like them. But an a Israeli desert plant called Ochradenus baccatus has found a strategy to transform a seed eater into a seed disperser. The plant produces sweet white berries, which attract desert mice. But inside the berries, tiny black seeds are plotting against the mouses’ bite. The seeds contain an enzyme called myrosinase, which converts compounds in the sweet pulp into the pungent compounds that give mustard and wasabi their distinctive “kick”. When a mouse biters into the seed, it releases the myrosinase and all of a sudden, it gets hit with a mustard techno party in its mouth. The mouse consequently spits the seeds, becoming a vehicle for its dispersal. To confirm the hypothesis, Israeli scientists fed desert mice with treated seeds, with deactivated myrosinase: the mice ate 80% of them. When they were fed regular berries, the little creatures spat out over 2/3 of the seeds.
And speaking of mice, bats are often mistaken for flying rodents, but they are not related to rodents? Did you know there are >1200 species of bats? Even if you didn’t know that, you do know that some bats live on blood, right?
Do not kill the vampire bats: they become nastier. Vampire bats are responsible for the majority of the cases of rabies in Latin America. This includes not only human victims but also livestock; it is estimated that they cause more than $30 million worth of damage to livestock each year. Governments have tried to curtail rabies transmission by killing the bats, but for unknown reasons, the strategy has backfired. Daniel Streicker, a postdoctoral ecologist at the University of Georgia in Athens, has been collecting blood samples from bats at 20 Peruvian sites for 3 years. Interestingly, the bat colonies that were periodically culled had higher rates of exposure than those were bats were never killed (12% compared to 7%). A possible explanation has to do with the killing method. When bats are captured, they are coated with an anticoagulant paste. Bats groom each other, so when these bats return to the colony, other bats eat the paste and die of internal bleeding. The problem is that only adult bats groom other bats, and many adults have acquired resistance to rabies so they don’t spread it. But juveniles are not resistant to rabies, they do not groom other bats, hence the number of juveniles who are susceptible to rabies and can transmit it, increases. Moral of the story: host-pathogen interactions are very complex and you better have a good understanding of the ecology of these interactions before intervening. Perhaps vaccinating the bats is a better strategy than killing them.
From nasty blood-sucking mammals to peaceful, vegetarian mammals, the genome of the genome has been sequenced. It was the last of the great apes to have its genome fully sequenced:
Bonobo genome: bonobos as close to humans as chimpanzees. The completion of the entire genomic sequence of the bonobo (Pan paniscus) put an old debate to rest: that we are more related to chimps (Pan troglodytes) than to bonobos. It turns out that bonobos as 98.7% similar in DNA sequence to humans, the same as chimpanzees. The two species are 99.6% similar to each other; their last common ancestor was ~ 1 million years ago; the two groups probably got separated by the Congo river and gave rise to the two species; there is no evidence, genetic or of other type, that they have interbred ever since. The last time we shared a common ancestor with chimps and bonobos was >5 million years ago. Interestingly, there is 3 % of our genome that is more closely related to bonobos than to chimps, and 3% that .is more related to chimps than bonobos. The explanation: when the ancestral population split, the different groups retained different subsets of sequences from the common ancestor. Interestingly, Another bonobos and humans, but not chimps, have the same version of a protein found in urine, that in mice functions to detect scent differences used as social clues. Only one bonobo genome has been sequenced so far, that of an 18-year-old female living in a German zoo; we will need to sequence the DNA of more bonobos in order to start figuring out what the DNA differences mean in terms of behavior, for example.
From one of our closest extant relatives to our very close, extinct human cousins:
Red dot is oldest cave art: was it Neanderthals? A new method of dating cave art called "U-series" has pushed the date of the oldest cave art, a single red dot in a Spanish cave, to a minimum of 40,800 years ago. U-series dating is based on the fact that calcite (calcium carbonate found in stalactites and stalagmites) contains trace amounts of uranium-238, which decays to thorium-230. The ratio of thorium-230 to uranium-238 can provide a date for when the calcite was laid down. An English team of dating experts took samples from the calcite overlaying cave art in 11 caves in northern Spain; since the calcite was laid on the paintings, its age can be used to deduce that minimum age for the painting. Since 40,000 years ago, Neanderthals inhabited Europe, and Homo sapiens was just arriving, the finding raises the possibility that Neanderthals painted the red dot. The red dot was found among other cave art, mostly handprints. But the date falls a bit short of a confirmation that Neanderthals were cave artists.
We have certainly come a long way since those beautiful handprints were painted: we can now imagine and achieve creating new organs in the lab to replace diseased ones:
Human eye precursor grown in the lab from stem cells. Stem cells have the potential to be used to generate organs in vitro. And now Japanese scientists at the RIKEN Center for Developmental Biology in Kobe, Japan, have succeeded in growing the precursor of a human eye in the lab. The eye precursor is a small structure, 550 micrometers in diameter, called an optic cup. The structure is formed of layers of retinal cells that include photoreceptors. The coolest thing is that the structure built itself: the cues to form the cup come from within the stem cells themselves. Retinal precursor cells spontaneously formed a ball of epithelial tissue cells and then bulged outwards to form a bubble. The bubble folded back on itself to form a pouch, with an outer wall and an inner wall containing the photoreceptors (the two layers can be seen in the image). This finding settles a long debate as to whether the development of optic cups occurs by external cues or internal cues. Scientists hope that these structures can one day be transplanted and integrated into the tissue to restore eye function.