PHOTO OF THE WEEK: Juvenile emperor angelfish
Doone, who regularly finds truly beautiful photographs of nature, posted a series of photographs of very colorful fish with fantastic patterns. Visit the photographs here. Don’t forget to look at the rest of the photographs of perhaps our most beautiful recurring thread, Beautiful Photographs of Animals and Nature.
ASTRONOMY: Dreams of water on Mars evaporate. The presence of water on the red planet was fiercely debated over the last century and a half, and although nowadays Mars is known to be dry (with the possible exception of some deep groundwater), astrophysicists thought that Mars had a wet past, with ancient lakes and even oceans. But new climate models now assert that Mars was cold and dry since the beginning. According to these new models, in ancient Mars, temperatures were never high enough to allow for liquid water. The famous Martian valley networks, with their iconic channels, were probably formed by the sporadic presence of water, isolated events both geographically and in time, not an indication of a generalized wet climate. The new findings don't definitively rule out the possibility of microbial life in ancient Mars, but instead "moves it" to deeper ground where the conditions were more stable.
NEUROSCIENCE/ANIMAL BEHAVIOR: Baboons can read. Sort of. The pattern recognition abilities that allowed us humans to become readers and writers can already be seen in baboons. Our very distant cousins can be taught to distinguish real English words from garbled letters that form no words. The monkeys are not really reading, but they are using object recognition to distinguish real words from made-up combinations of letters. Six adolescent baboons were shown four-letter strings of words on a computer screen, that formed either real English words or meaningless combinations of letters, such as 'DRAN' or 'TELK' (note that these resemble real words). When they touched the screen over a real word, they got a food reward. Over a month and a half, the primates were subjected to roughly 50,000 tests. The end result: they learned to identify words with an average of 75% accuracy Each of them learned between 81 and 308 words from the 500 real words they were taught, and distinguished them from the >and 7,000 randomly generated "nonwords" that they were shown. Baboons were best at identifying words containing very common English "bigrams" (combinations of two letters). This shows that they were truly learning a pattern and and not just memorizing the words, which would have been nevertheless impressive. Researchers think the baboons probably identified the English words by using orthographic information, meaning the identity and position of the letters within each word. It has been shown by previous studies that humans use similar cues when reading.
EVOLUTION: Tiny fish reveal big clues about adaptive evolution. The lowly stickleback, a tiny spiny armored fish that has freshwater and saltwater populations, has revealed the path of fast adaptive evolution to different environment. the punch line: evolution acts on existing variation, and channels the same genomic regions over and over to achieve the same effect: adapting to a new environment, in this case, freshwater. Sticklebacks are being called "the finches of the fish world" because they provide a beautiful model to study vertebrate evolution. Sticklebacks were originally just saltwater inhabitants. When the last Ice Age ended some 10,000 years ago and glaciers retreated, sticklebacks invade the world’s rivers and lakes, adapting in a very short time (10,000 years is a very short time in evolutionary terms), to freshwater. Their salt tolerance, diets, kidney function, coloration, etc., changed. They shed their armor, because they faced faster but weaker predators than at sea. A population from an Alaskan lake changed from highly armored to weakly armored in just 13 generations! Scientists have now sequenced the entire genome of 21 different populations of saltwater and freshwater sticklebacks, and found that freshwater fish picked up basically the same genetic changes independently in different parts of the world, by tweaking the same genomic regions. Importantly, the researchers found that about 80% of freshwater adaptations happened by changing regulatory DNA, and not by effecting amino acid changes. This is crucial because regulatory changes would speed adaptation by controlling gene expression in multiple tissues, from only one or very few mutations. The study also highlighted that stickleback evolution is accelerated by the use of pre-existing genetic variation, therefore there is no need for new, random mutations to arise. A little fish, a big headache for the creationists.
GENETIC ENGINEERING: Transgenic mosquitos to combat dengue. A program to use genetically modified (GM) mosquitos to combat or even eradicate dengue fever in Brazil is having pretty spectacular results. Male mosquitos were genetically engineered to carry a "poison pill" in their genes: a gene that provokes the death of the progeny before reaching adulthood. Lowering the population of mosquitos will lower the transmission rate of this serious viral disease, since mosquitoes are the insect vector. Over 10 million GM male mosquitoes were released over a 300,000-people Brazilian city, Juazeiro, in Eastern Brazil in the state of Bahia, in a period of one year, and currently, >80% of eggs collected around the area carry the lethal transgene. The GM mosquitos are being tested in the Cayman Islands and in Malaysia too. So, if the gene is lethal, how can you raise large numbers of males carrying the lethal gene? A repressible system has been used to express the lethal gene, and repression can be maintained in the lab by feeding tetracycline (a cheap antibiotic) to the mosquitoes. Once released in the wild, there is no tetracycline around so the lethal gene, a transcriptional activator, is highly expressed, and kills the carriers. The experiments are being closely monitored for unexpected problems with the GM mosquitoes. Males were chosen to carry the lethal gene because they do not bite humans, only females do.
ENTOMOLOGY: Virus controls the minds of parasitic wasps. Nature can really be so fascinating at times. I find parasitic wasps to be terrifying insects: they lay their eggs into caterpillars or maggots that get eaten from the inside out by the wasp progeny. And it turns out that the parasitic wasps themselves are in turn parasitized by a virus that controls their behavior! The parasitic wasp Leptopilina boulardi usually lays only one egg per maggot, and if the maggot has already been "infected by another wasp's egg, they refrain from laying there, because maggots can optimally support only one wasp grub. But when L. boulardii is infected with a virus called LbFV, (L.boulardii filamentous virus), the wasp stops caring whether the maggots are "occupied" or not. the virus benefits because this virus is heritable, it gets transmitted from adult wasp to egg and also from egg to egg! It's a win-win situation for the virus. But there's another twist, L. boulardii competes for maggots with L. heterotoma, a weaker cousin species whose eggs die when they are in the same host with L. boulardii's eggs. But the virus turns the tables for L. heterotoma, allowing both species to co-exist in the same beautiful French countryside area. Because infected L. boulardii wasps "lose their minds" and keep laying eggs in maggots where other L. boulardii has laid eggs before, the eggs die off and there are less L. boulardii wasps top compete with the cousin species. The virus does not infect L. heterotoma, and scientists don't have the faintest idea how the virus manages to control the wasps behavior. I can't wait till they find out!
HIGHLIGHTED DISCUSSION: Camouflage-Spectacular images. Camouflage is an extraordinary adaptation; many of the photographs in this discussion will leave you scratching your head and squinting your eyes, trying to find the hidden animal.
Science bits and news from other sites:
CRAZIEST TITLE OF THE WEEK: "Intelligent Alien Life Could Resemble Earth's Extinct Dinosaurs" --New Research Says. The Daily Galaxy, a supposedly science news site, writes: “New scientific research raises the possibility that advanced versions of T. rex and other dinosaurs — monstrous creatures with the intelligence and cunning of humans — may be the life forms that evolved on other planets in the universe”. Yes, my dear friends, you are reading correctly; and if your first thought is that this is the most absurd baloney you’ve ever heard, well, you’d be right! Dr. Ronald Breslow just published a paper speculating on the origin of the homochirality of amino acids in The Journal of the American Chemical Society. Chirality refers to the orientation of chemical compounds, which can be left-handed or right-handed, just like mirror images of each other. Curiously, amino acids on most life forms on Earth (which the exception of a few bacteria) are found only in the left-handed form, or L-form (thus they are said to be “homochiral”), while sugars are mostly on the D-form (right-handed). Dr. Breslow shows how D-sugars can be derived from L-amino acids in a prebiotic environment, and based on the finding that a meteorite that landed on Earth in the 1960s had only L-amino acids, he speculates that meteorites could have “seeded” these chemical forms, thus giving rise to the common chiral forms that make life on Earth possible, such as the D-sugars that are part of the DNA molecule. Of course, Breslow clarifies that he is speculating, and that if a meteor would be found with D- amino acids, his hypothesis would be falsified. But incredibly, he ends the paper with this: "An implication from this work is that elsewhere in the universe there could be life forms based on D-amino acids and L-sugars. Such life forms could well be advanced versions of dinosaurs, if mammals did not have the good fortune to have the dinosaurs wiped out by an asteroidal collision, as on Earth. We would be better off not meeting them." I kid you not. I copied the sentence verbatim. Of course, nothing in his works implies even remotely that alien life forms could be like intelligent dinosaurs! His research says nothing about alien life forms. The way this sentence is written, I’m willing to bet good money that Dr. Breslow threw that sentence in the article to see how closely the editors and reviewers were paying attention. Obviously they were not. Unfortunately, many unscrupulous or ill-prepared journalists are reporting crazy stuff like “research says there could be intelligent dinosaurs on other planets.” Sigh.
Dark matter has just collided with your body. Dark matter does not absorb or emits electromagnetic radiation, making it virtually impossible or very difficult to detect. Dark matter is made up of weakly interacting but massive particles (WIMPs, for short), which physicists continue to search for. We know it must exist because of the discrepancy between the mass of large astronomical objects determined from their gravitational effects, and their mass calculated from their visible matter (stars, gas and dust). Since dark matter is in theory about five times more abundant than visible matter, and is all over the place, some of it must collide with the human body (or any body, for that matter, no pun intended), the question is how often. Katherine Freese at the University of Michigan in Ann Arbor, and Christopher Savage at Stockholm University in Sweden teamed up to calculate precisely this, and published their results at arxiv.org (arxiv.org/abs/1204.1339). Dark matter does not interact very strongly with regular matter; otherwise physicists would have detected its effects already, and it still remains elusive. Freese and Savage calculated how many times atom nuclei in the average-sized human body (a 70 kg chunk of flesh made of oxygen, hydrogen carbon and nitrogen) collide with dark matter particles. According to them, dark matter is most likely to collide with oxygen and hydrogen nuclei in the body, and based on the latest experimental results, this would happen about 100,000 times a year for each human. Chances are this collision has happened to you a few times while reading my blog. The potential effects on health due to this background collision hit rate are probably negligible, plus we can’t do anything about it, so why worry? But is fun to speculate that it could cause some tissue damage depending on the energy and motion of a nucleus after it had been hit. It’s simply another reminder that our bodies are constantly bombarded by particles, UV radiation, etc., and that these events all result in some degree of tissue damage.
Physicists Create First Long-Distance Quantum Link. Quantum physics-based methods could be used to create communications that in theory cannot be intercepted, and physicists have been trying to develop these methods for over a decade, without much success. A small breakthrough has finally happened this week, when a German announced the first true quantum link using two widely separated atoms. The results were reported online this week in Nature. The important difference is that in the past, networks communicating quantum information had to convert it into classical information at the network switching points. If the key is passed from node to node in a quantum fashion, but is read out and regenerated at each node in the network, it leaves leaving the nodes vulnerable to hacking or eavesdropping. In these recent preliminary experiments, the information remains in quantum form, because the nodes themselves are made out of individual atoms. Stephan Ritter of the Max Planck Institute of Quantum Optics in Garching, Germany, and his team, have entangled two atoms in separate labs across the street. The problem is that a lab full of sophisticated equipment is needed for each quantum node. Each atom sits between two highly reflective mirrors, placed 0.5 mm apart, which is termed an “optical cavity”. When a laser is applied to the first atom, it emits a photon that travels through a 60-meter-long optical fiber to the optical cavity across the street. As the second atom absorbs the photon, becomes entangled with the first atom. This entanglement can be extended to a third atom, to make a third node. It is a very important advance, but a lot of work is needed before the technology is practical. The researchers are planning to start by miniaturizing the components in each node.
Less time separates us from T. rex than T. rex from stegausaurs. Now this is a real dinosaur science story, unlike the loony “intelligent alien dinosaurs” sound bite. It’s impossible to understand life on Earth, biology, evolution, without having a sense of deep time, geological time. This applies to everyone’s favorite extinct beasts, the dinosaurs. But since many of our estimates are in +/- millions of years, paleontologist Brian Switek finds a way to put it all in perspective for us. The Mesozoic Era, also known as the Age of Dinosaurs, lasted from about 250 million to 66 million years ago. But not all dinosaurs lived throughout all of the Mesozoic. Diplodocus, Apatosaurus, Allosaurus, Stegosaurus and their neighbors roamed western North America about 150 million years ago, in the late Jurassic. In contrast, Tyrannosaurus and Triceratops did not appear until the latest Cretaceous scene, 67 million years ago. So 83 million years separated Apatosaurus and Allosaurus from Triceratops and T.rex. The Age of Mammals, which started when dinosaurs (that is, non avian dinosaurs) became extinct, started about 66 million years ago. Therefore, less time separates humans from T. rex than separated T. rex from Stegosaurus. Think about all that happened in these past 66 million years! How is that for perspective?
Changes in monkeys' social status affect their genes. The social status of female rhesus macaques affects the expression of ~ a thousand genes in their white blood cells. And the higher the social status, the healthier the animals were found to be. Incredibly, looking at the pattern of gene expression of individual females can be used to predict their social status with 80 % accuracy. Social status has been previously shown to affect gene expression in insects and fish, this is the first time it’s show to affect a mammal. In the past, scientists have observed that the social environment of primates affect their hormone levels, mortality risk, and the survival of their offspring. Evolutionarily speaking, it pays to be top monkey. In order to study this, the researchers formed new social units at the Yerkes National Primate Research Center at Emory University in Atlanta. Lower-ranking monkeys had lower levels of certain types of T cells and showed signs of chronic stress. These physiological changes could explain the gene expression changes seen in their blood cells. A monkey’s rank in the hierarchy correlated with the presence or absence of methyl groups in their DNA, which contribute to the switching on and off of genes. Gene expression changed in the macaques when their social status changed, and positive effects on the expression of immune system genes were observed when the monkeys increased their social status in a newly formed unit. Their immune systems changed rapidly and formerly low-ranking animals ended up having no gene expression differences with animals that had always been high-ranking. This means that many of the changes aren't permanent and regulating stress can have a beneficial expression on gene expression and consequently, general immune system health. The results could provide insight into how to manage stress caused by social status in humans.
Vomiting caterpillars. Did you like to gross out your friends when you were a little kid, by picking up earthworms or dead rodents? I did. Today I feel like a kid again (must be my new hair cut) so I’m going to tell you about caterpillar puke. It turns out that some caterpillars have developed a great form of defense: when attacked by a bird or another predator, they vomit a green fluid of semi-digested leaves, which smells unpleasant to the predators. But of course, if caterpillars threw up their food all the time, their growth would be impaired by inadequate nutrition, reducing their survival rate. Now a new study published in Ecology Letters shows that a caterpillar is more likely to vomit when it is alone than when there are other caterpillars around. It is a way to evaluate the cost of vomiting. In a group, other caterpillars may end up vomiting and the unpleasant stench will turn the predators off from all the caterpillars on the branch or leave, but if the little caterpillar is by itself, it must protect itself. Also, caterpillars compete with each other for food. Scientists study this vomiting strategy to combat crop pests, such as P. brassicae, that eats cabbage. For example, birds trying to prey on P. brassica have benefits beyond the number of caterpillars they eat, because they put pressure on them, and causing vomiting reduces the fitness and reproductive rate of the pests. And if you’re not grossed out enough already, check out this video of P. brassicae regurgitating green goo.