Courtesy Striving to a goalSomewhere, deep in the recesses of animal evolution, a mass of molecules known as opsin mutated from a run-of-the-mill protein into a detector protein with great vision. Not vision in the figurative way, but vision in the literal way. Opsin is the protein in the photopigments of your eye that interacts with light, and allows you to see all the wonderful things visible in the universe. If you’re reading this post, you have the opsins in your eyes to thank.
Here’s how it works. When a particle or wave of light (a photon) enters your eye, the light sensitive opsin traps it using a small chromophore molecule in it architecture called retinal. Normally, retinal’s tail is all twisted and bent, tensed up, and waiting for something to happen. That’s just the way retinal is when it’s chilling out. But when a photon hits it, the light particle interrupts retinal’s naptime, and the molecule reacts by straightening out its tail. The tail’s movement starts a chain reaction of sorts activating the opsin, which in turn, activates a nearby nerve that shoots out a signal that your brain perceives as light.
Three types of opsin can exist in the eye: R-opsins (rhabdomeric), C-opsins (ciliary, and Go/RGR-opsins (Go-coupled/retinal G protein-coupled receptor). The R and C opsins, depending what type of animal you are (e.g. vertebrate or jellyfish), are used for detecting light. Go/RGR-opsins don’t detect light but are used instead to help regenerate retinal cells and regulate an animal’s inner clock or biological rhythms. Scientists have known about opsins since the 19th century, but haven’t known much on how they evolved, or how they became designated light detectors.
In a recent study published in the journal PNAS, Roberto Feuda of the Department of Biology, National University of Ireland Maynooth, and colleagues reported on their detailed examination of the genetic trail of opsins in all kinds of animal life, from sponges and jellyfish to reptiles, birds and mammals. And while their results warrant further study, they did add new knowledge to our understanding how the eye evolved.
The study negated a long-held idea among scientists that only certain light-designated opsins were present in certain animal types. Generally, C-opsins were thought to be present only in vertebrates, and R-opsins only in invertebrates. But the study showed otherwise. It postulated that all three forms of opsins probably existed in the earliest common ancestor right from the beginning. Later, somewhere along their respective evolutionary lines each group designated the C or R opsins for light detection. The leftover opsins (whether C or R) were used for other non-visual purposes such as setting biological rhythms.
It also pushed the origins of light-sensitive organs back a couple hundred million years from about half a billion years ago to three-quarters of a billion years ago, a time not long after sponges had diverged from other animals and before they split into Bilateria and Cnidaria. Within that evolutionary timeline opsins were found in the gene sequence of the tiny and transparent shape-shifting microorganisms called placozoa. However, because the genome lacks a critical retinal-binding amino acid - lysine 296– it’s unlikely these opsins were able to detect light. (It should be noted that placozoan phylogeny is still under debate). But somewhere along the evolutionary line, these non-visual opsins mutated into a light sensing protein. After just two more gene duplications the three opsins, R, C, and Go/RGR we find in our eye’s photopigments today, were already present in the genome.
Why or when opsins developed into part of the eye’s photopigment is anyone’s guess. This research doesn’t solve all the mysteries surrounding them, particularly their non-visual functions but it does fill in some of the gaps in our understanding of key components of vision evolution.
Courtesy Mark RyanI don’t have a clue who or what entity officially proclaimed October as International Dinosaur Month (and there doesn’t seem to be any official site online), but whoever it was, it’s a great idea! This means not only do we get to celebrate Earth Science Week (October 14-20), and National Fossil Day (October 17*) this month but we also get to celebrate everyone’s favorite prehistoric beasts! A quick Internet search brought up a couple teacher sites here, here and here each offering some interesting ideas on how to celebrate the great Mesozoic monsters this month. There's also this International Dinosaur Month site on Pinterest , and another Pinterest site (mine) featuring dinosaur postcards. Or you could go view some dinosaurs at a local or nearby museum. Below, I’ve included a few museum links to dinosaur-related exhibits, and a site that lists dinosaur exhibitions around the world. If you or your classes are celebrating dinosaurs this month or have other suggestions on how to do so, please let us know.
*The Science Museum of Minnesota will celebrate National Fossil Day on Saturday, October 20 this year.
Courtesy Photo and sculpting by Tyler Keillor via ZookeysA fossil found in South Africa over 50 years ago has finally come to light as a new species of heterodontosaurid dinosaur and named Pegomastax africanus, or "thick jaw from Africa". No larger than a house cat, Pegamstax lived about 200 million years ago near the very beginning of the Jurassic period. The bizarre, two-legged herbivore had a beak like a parrot but also large, sharp vampire-like fangs that were backed up by a couple of equally nasty bottom teeth. Although unusual for a plant-eater, the sharp teeth would have been useful in nipping off leaves, twigs, and other tasty plant morsels, or for defending itself against predators or mating rivals. It may have also sported some nasty porcupine-like quills for further protection against predation.
Paleontologist Paul Sereno of the University of Chicago first laid eyes on the fossil while a graduate student at a Harvard University laboratory back in 1983. Other projects, however, diverted his attention from the rare specimen until recently when he finally found time to analyze it and publish his conclusions in the journal Zookeys.
News of the mini-dino “vampire" couldn’t have come at a better time, and all you little rug-rats out there who haven’t decided yet what to be for Halloween should find comfort in the announcement. A prickly Pegomastax costume would make for one scary night creature, and probably guarantee you bagfuls of delicious, (and perhaps, ironically) fang-rotting candy.
Courtesy NASA / JPL-Caltech / Dr. Philip Bart, LSURecent investigations into microfossils show that Antarctica hasn’t been quite the icebox scientists have imagined it to be over the past 34 million years. Pollen and leaf wax samples from Miocene-aged sediments indicate the continent has experienced some periods of warming since the beginning of the most recent glacial period. The core samples studied came from ocean sediments collected near Antarctica, and particulates found in the samples indicate more rain fell on the ice-covered continent during the Middle Miocene epoch (15.5 – 20 million years ago) than previously thought, enough rain to spur the growth of forests of small, stunted trees.
Paleoclimatologist and organic geochemist Sarah Feakins of the University of Southern California and her colleagues analyzed core samples taken from between 144 and 1,100 meters beneath the ocean floor – levels dating back to the Middle Miocene. Spikes of concentrated amounts of pollens and leaf wax appeared in two periods – one about 16.4 million years ago, and another about 15.7 million years ago. The warm periods were relatively short, each lasting less than 30,000 years.
In a previous study, palynologist Sophie Warny of Louisiana State University had first described the pollen and leaf wax spikes found in the core samples, and she and Feakins eventually teamed up for the recent study. The team determined the particle spikes didn’t arise from the leaf wax and pollen blowing in from elsewhere but rather came from two species of trees that once lined the shores of Antarctica. The two species, podocarp conifer and southern beech wouldn’t have grown very tall – maybe knee-high – and neither spreads their pollen over wide areas. Had the pollens blown in from elsewhere - say South America or New Zealand - there were would have been more species in the mix.
Using a mass spectrometer, Feakins and NASA researchers analyzed the ratio of hydrogen to deuterium atoms in the wax molecules which indicated the temperature at the Antarctica location during the two warm periods was about 7 degrees Celsius during the summer. Today, summer temperatures in the same region are about –4 °C. The average global temperature at the time was about 3 °C higher than it is today. As the overall global temperature changes a relatively greater change in polar temperature isn't unexpected due to a process called polar amplification.
The data from Feakins and Warny’s study, which appeared in Nature Geoscience, adds to growing concerns over the sensitivity of Earth’s climatic and hydrological systems. At the moment, no trees line the shores of Antarctica, but current levels of carbon dioxide (393 parts per million) are not far off those thought to have existed during the Middle Miocene’s warm periods (400-600 parts per million) when forests did exist on the margins of the icy continent. This could indicate that even small changes in carbon dioxide levels can are capable of creating big changes in climate.
Courtesy Illustration by Cheung Chungtat via PLoS ONEThe stomach contents of two carnivorous dinosaur skeletons discovered in China show evidence of both bird and dinosaur remains, raising questions about the carnivores' behaviors in acquiring the meals. The two predators, both species of Sinocalliopteryx (and larger cousins of Compsognathus) came from the Early Cretaceous-aged Jianshangou Beds of the lower Yixian Formation in Liaoning province.
The holotype of Sinocalliopteryx gigas included the skull and skeleton, and also signs of “long filamentous integument”, i.e. feathery fuzz. Inside its gut researchers detected the remains of a dromeosaurid (Sinornithosaurus?). The abdomen of the second, recently discovered specimen contains the remains of not one but two primitive birds of the species Confuciusornis sanctus. It also contains the bones of a possible ornithischian dinosaur.
The researchers, led by paleontologist Lida Xing of the University of Alberta, can’t say for certain how the second Sinocallioptyryx acquired the two birds, but several hypotheses have been made. One is that S. gigas was a stealthy hunter with the prowess of a modern day cat, able to stalk and pounce on the unsuspecting early avians. Another possibility is that Sinocalliopteryx scavenged the Confuciusornis meals. But because the remains of the two primitive birds are in the same proximity in the Sinocallioptyryx gut, and show similar levels of being digested, this latter hypothesis opens the question of what would have been the possibility of two C. sanctus dying (or being killed by something else) in such close proximity to each other. The cat-like behavior seems more likely. It could also be possible that the two primitive birds were fledglings that fell out of their nest, or just weren’t as agile as modern birds are in taking flight to avoid predatory attacks.
The remarkable Sinocalliopteryx fossils have also revealed new information about how the digestive systems of some dinosaurs operated. The dinosaur bone found in S. gigas gut is degraded and heavily corroded by stomach acid. Whatever kind of dinosaur it was, it seems to have been consumed first, followed later by the two Confuciusornis. Similar corrosion isn’t evident in the two confuciusornines specimens suggesting S. gigas was still digesting the ornithischian meal when it caught and ate the two avians in fairly rapid succession. This also points to S. gigas having a high rate of metabolism, unlike most reptiles and more like that of modern birds.
Most modern birds egress (vomit) up bone material and don’t try to digest it, while alligators and some vultures living today are able to break down bone material with strong stomach acid in a foregut. A cold-blooded alligator would need about 13 days of digestion to reach the apparent level of bone corrosion seen in the gut of the S. gigas, while warm-blooded birds would need only about 12 hours.
So what kind of scenario does all this intestinal evidence present? Was Sinocalliopteryx gigas a catlike predator that actively hunted, killed, and consumed its own meals, or was it just an opportunistic scavenger of leftovers and road kill? I tend to favor the stalk and pounce method but further evidence would be necessary to say for certain. In the meantime, you can read all about this recent study online in the open access journal PloS ONE.
Courtesy Mark RyanIt’s that time of the year again when hawks, eagles, and other raptors head south for the winter. That means lots of folks will be migrating to Hawk Ridge Nature Reserve on the western tip of Lake Superior to view the annual event.
Because the birds don’t like crossing wide expanses of water, tens of thousands of them funnel into the port city of Duluth, Minnesota from regions north to get past Lake Superior.
I was in Duluth this past weekend, and official bird counters were already at the main overlook tracking and recording birds that have already begun their migration south. But don’t worry, if you’re a birder (or just someone who enjoys one of the best urban views of Lake Superior), there's still plenty of opportunity to participate in the annual aerial stampede.
According to the Hawk Ridge Bird Observatory website, the best viewing times depend on the weather and wind direction.
"Birds and the weather are both unpredictable, but here are a few tips for predicting the flight: Northwest or west winds are best, and the more in a row, the better. North and southwest winds are okay. South, southeast, and east winds are not good. The day before or a couple of days after a strong front usually produces more birds. The flight essentially shuts down in the rain, and if they move in fog, we can't see them!“
Although the migration continues into November, mid-September seems to be the peak time to see the most birds. And if you really want to get in the thick of it, plan to be at Hawk Ridge in a few weeks for the big Hawk Weekend Festival on September 14, 15, and 16. The event includes presentations, field trips and, as expected, lots of bird-watching. If past years are any indication, flocks of bird-lovers and naturalists will be there, too. At minimum, you should at least bring a decent pair of binoculars.
Courtesy Mark RyanThe birds flying in like to catch rising columns of air known as thermals and ride them over the ridge. When I was there, a kettle of turkey vultures (Cathartes aura) was doing just that. It makes for some extended observation time and somewhat easier photography than if they were just doing a flyby.
If you plan to go, just know that last weekend the east entrance to Hawk Ridge (Seven Bridges Road) was still closed from last June’s flooding. The best remaining access to the ridge is from Glenwood Avenue. One way to get there from downtown (and the easiest to explain) is to take Superior Street east to 45th Avenue East and then north (left) to Glenwood Avenue. Another left takes you up about a half-mile to the crest of the hill where the entrance to Hawk Ridge is located. The entrance is marked with a large sign and is a rather sharp-angled right turn so be prepared for that.
Courtesy wattpublishingI don’t know if you are following the recent news about a new flu strain or not but it looks like the strain (H3N2v) is now in MN. Pigs can spread this virus to other pigs and humans through airborne droplets (coughs and sneezes). If you are a meat eater, don’t worry you can’t catch it by eating pork.
Will you be visiting the pig barns at the Minnesota State fair this year?
One case of the new swine flu (H3N2v) has been confirmed in MN. For information about this new strain see the fact sheet posted at flu.gov . I’ve heard 3 different reports on how concerned we should be about the situation:
Do you think Dr. Osterholm is being alarmist or is the threat real? Will you be visiting the swine barn at the fair? What questions do you have about the situation? Do you need more information? I'd love to hear your thoughts!
Courtesy titanium22The Minnesota State Fair starts next week and as you prepare to go, you just might want to assess your flu risk in the swine barn.
Researchers at the University of Minnesota have just announced the results of a study they conducted at the 2009 fair, testing pigs for the H1N1 flu virus that was spreading widely across the nation at that time.
Their findings showed that 19 percent of the pigs they tested at the fair that year had the virus. Some appeared to be perfectly healthy, exhibiting no flu symptoms. Two pig exhibitors from that year's fair from the same family came down with the flu from pigs they were showing, researchers added.
Adding some urgency to the announcement of the study is a new nationwide outbreak of a different strain of swine flu this year: H3N2v. More than 150 people across the country have come down with symptoms of this new flu.
So does this mean you should stay away from the pig barn? Not entirely, fair officials say. Veterinarians will be conducting extensive testing of all pigs coming to the fair this year. And the fair has issued this guidelines to help people decide how much time, if any, they should spend with the pigs.
• Avoid eating in the barns
• Use hand-washing stations after visiting
• Skip the barn if you feel ill
People who are at high risk for flu should also consider avoiding the swine exhibit entirely – including children younger than 5, pregnant women, people 65 and older and those with chronic conditions.
You may now resume eating your pork chop on a stick, but first share with Science Buzz readers your thoughts about visiting the pig barn at this year's fair.
Courtesy Public domain via Wikipedia This cool evolution timeline is really fascinating and fun to mess around with. I'm guessing Charles Darwin would agree it's a vast improvement over the one that appeared in Punch Almanac in1882 when he was still alive (see image at right). This new one was created by John Kyrk, a biology-trained artist in San Francisco in collaboration with Dr. Uzay Sezen, a plant biologist from the University of Georgia. The timeline is available in several languages and would be very useful in a classroom setting when studying evolution and paleontology.
The site is interactive and follows the evolution of our universe from the Big Bang to the present. You start it by clicking and sliding the red pyramid on the right. As you scroll across the timeline, various events in the history of the Universe, Solar System and ultimately, the Earth show up on the screen. All along, links also appear that either explain concepts or show examples of them. In the upper left hand corner is a menu linking you to several corollary Flash animations by Kyrk explaining cell biology and how RNA, DNA, cells, water, and other basic elements of life (including viruses) operate. Kyrk thinks animated illustrations are very useful in teaching and remembering ideas and concepts.
All the phases of Earth’s formation and development are covered in the evolution timeline, including the Late Heavy Bombardment, Snowball Earth, Cambrian Explosion, stromatolites, photosynthesis and iron formation. Once life begins to rise up, your computer screen will run amok with Earth’s diverse species populations from the one-celled animals, trilobites and fish to amphibians, reptiles, dinosaurs and mammals – the whole shooting match. All the major extinction events are shown, too.
The site also contains a link to this YouTube video version of someone else working the timeline so you can just sit back and watch how it happens, But I recommend working the interactive page yourself. A lot more happens and is available than the video allows you to see. Note that you’ll need Flash for it to run on your computer.
I wonder how Darwin would have reacted if he were able to see his theory illustrated in this way?
Courtesy Warner Nature Center
Courtesy Warner Nature CenterApril 30 our nature center had a visit from a black bear. Apparently after 5 years of ignoring our bird seed storage under our stairs the bear decided it was time to eat.
We set up 2 cameras to see if the bear would come back. Did he ever. Both May 1 and 2 he showed up. After tearing half the door the first night the bear was back and rolled out a can of seed. The metal lid was peeled back as if it were aluminum foil.
The squirrels and raccoons took full advantage of the seed being strewn around. Piles of bear and raccoon scat were found on site the next day, sweet.
Four more days of setting out the cams showed that 3 days of bird seed was enough.