Stories tagged biology

Apr
29
2013

Coelacanth: model in the SMM paleo lab. Photo by Mark Ryan.
Coelacanth: model in the SMM paleo lab. Photo by Mark Ryan.Courtesy Fancy Horse (underwater background)
The genome of the coelacanth, the world's best known living fossil, has been sequenced by an international team of researchers and is revealing something scientists already suspected: that the primitive-looking fish has evolved more slowly than most other organisms. The coelacanth is related to the lungfish and several extinct Devonian fish species that are considered precursors to land dwelling tetrapods. Kerstin Lindblad-Toh is senior author of the study which appeared recently in the science journal Nature.

"We often talk about how species have changed over time, but there are still a few places on Earth where organisms don't have to change, and this is one of them," Lindblad-Toh said. "Coelacanths are likely very specialized to such a specific, non-changing, extreme environment -- it is ideally suited to the deep sea just the way it is."

Lindblad-Toh is scientific director of the Broad Institute's vertebrate genome biology group in Cambridge, Massachusetts, which did the genome research. The institute is linked to both MIT and Harvard.

The genetic map, which involved sequencing some 3 billion letters of DNA, also showed (via RNA content) that tetrapods - four-legged land dwelling animals - though related to both coelacanths and lungfish, are more closely related to lungfish and followed that line rather than that of the coelacanth. We humans also branched off that same line. The genome of a lungfish is composed of over 100 billion DNA letters, making it a much more difficult task to sequence, so for the time being, the coelacanth's DNA makes for a reasonable alternative for study.

"This is just the beginning of many analyses on what the coelacanth can teach us about the emergence of land vertebrates, including humans, and, combined with modern empirical approaches, can lend insights into the mechanisms that have contributed to major evolutionary innovations," said professor Chris Amemiya at the University of Washington, and the paper's co-author.

Fossil coelacanth: not much has changed in 350 million years.
Fossil coelacanth: not much has changed in 350 million years.Courtesy photo by Haplochromis via Wikipedia Creative Commons
When Louis Agassiz named the first fossil coelacanth back in 1836, the Swiss paleontologist probably never imagined that a nearly identical descendent of the primitively constructed Devonian-aged fish would one day be found still inhabiting the world's oceans. The coelacanth was thought to have gone extinct along with the non-avian dinosaurs at the end of the Cretaceous period. None have been found in the fossil record after that time, but two extant species are known today. The first specimen Latimeria chalumnae was netted off the coast of South Africa in 1938, near the Chalumnae river and retrieved by East London Museum curator Marjorie Courtenay-Latimer who discovered what she called "the most beautiful fish I'd ever seen" in the catch of local fisherman, Henrik Goosen. Since then several more coelacanths have been caught, including the Indonesian species, Latimeria menadoensis, from the Indian Ocean.

The remarkable prehistoric throw-back, sometimes referred to as "old four legs" because of its leg-like fins, hasn't changed much in its 350 million year history. A member of the clade of lobe-finned fishes called Sarcopterygii, coelacanths retain primitive characteristics such a notochord, a hollow fluid-filled tube made of cartilage that underlies the spine over the length of its body. In all other vertebrates, the notochord is an anatomical structure that appears briefly only during the embryonic stage but not in adults. Not so with the coelacanth. It also possesses, primitive shark-like intestines, a linear heart, and tightly-woven armor-like scales (known as cosmoid) that are only found on extinct species of fish. The coelacanth's brain case contains only 1.5 percent gray matter - the other 98.5 percent of space is filled with fat. The other end of the coelacanth body begins to taper before expanding into a strange, three-lobed tail. Its most notable features are its lobed pectoral and pelvic fins that are structured with bones that look like toes, and move in an alternating tetrapod manner. An electroreceptive rostal organ located in its snout is used to detect prey, and the coelacanth is the only living animal that can unhinge a section of the its cranium to increase the gape of its mouth, enabling it to consume larger prey.

The blue or brown, white-speckled coelacanths prefer deep-water environments, and can reach six and a half feet in length and weigh upwards to 175 pounds. For some reason no living coelacanth has managed to survive more than a single day in captivity. With a dwindling population estimated at only 500-1000 individuals, the coelacanth was declared an endangered species in 1989.

SOURCE and LINKS

Broad Institute news
Coelacanth info at dinofish.com
More coelacanth info
NatGeo article
Take Nova's Coelacanth Quiz

Feb
25
2013

OMG! Can nothing stop them?: According to a new study, mosquitoes, those buzzing, biting, itch-producing flying pests that make life miserable for many of Earth's inhabitants (mainly we humans), can easily adapt to Deet, one of the commonly used ingredients in insect repellents.
OMG! Can nothing stop them?: According to a new study, mosquitoes, those buzzing, biting, itch-producing flying pests that make life miserable for many of Earth's inhabitants (mainly we humans), can easily adapt to Deet, one of the commonly used ingredients in insect repellents.Courtesy Mark Ryan (with photo help from NASA)

We've all seen them, those great B-films where a giant, vicious monster from under the sea, or invaders from outer space arrive to cause mayhem across our cities and generally mess up our way of life. In the end, it seems no matter who or what it was that was attacking us, be it Mothra, Godzilla, or some race of belligerent extra-terrestrials, we could always count on the military to save our collective behind.

Unfortunately, with mosquitoes, that might now be the case anymore.

Scientists are reporting that Deet, one of the most widely used active ingredients in insect repellents, loses its effectiveness against mosquitoes shortly after those ubiquitous, blood-seeking winged vermin are first exposed to it.

Deet - the common name for N,N-diethyl-meta-toluamide - was developed by the US Army after the Second World War to help combat insects during jungle warfare. It was used extensively in the Korean and Vietnam wars, but mosquitoes seem to be able to adapt quickly to it.

"Mosquitoes are very good at evolving very very quickly", said Dr. James Logan of the London School of Hygiene and Tropical Medicine and co-author of the study. "There is something about being exposed to the chemical that first time that changes their olfactory system - changes their sense of smell - and their ability to smell Deet, which makes it less effective."

So what I want to know is where does that leave us here in Minnesota where the mosquito constantly competes with the Common Loon for the title of State Bird? Maybe it's time to start digging the bunker in the backyard.

SOURCE and LINKS
BBC Science news
Original study at Plos One
The Life Cycle of the Mosquito
All about mosquitoes on NatGeo

Turkey censors Darwin and evolution
Turkey censors Darwin and evolutionCourtesy Public domain via Wikipedia
There’s concern in the scientific community as the Republic of Turkey seemingly expands its censorship of evolution. Turkey is one of the more secular Islamic countries, but recent events seem to show a growing trend in the Turkish government's crumbling stance on evolution. In 2008, the country’s Council of Information Technology and Communications (BTK) banned access to evolution websites including www.richarddawkins.com, www.aboutdarwin.com and www.darwin-online.org.uk. (Access to some other previously banned evolution sites was later allowed). The next year, the cover story of a science magazine celebrating the 200th anniversary of Darwin’s birth was removed just before publication but later reinstated after public outcry. In 2011, Turkey’s Council of Information Technology and Communications (BTK) released secure “Child Profile” Internet filters that, along with guarding against access to pornography, blocked sites containing words such as “Darwin” and “evolution”.

Now the Scientific and Technical Research Council of Turkey (TÜBITAK) has stopped publication and sale of all evolution books its archives. The TÜBITAK website has long listed books by such evolution writers as Richard Dawkins, Stephen Jay Gould, and J a m e s W a t son as “out of stock”, but now titles by these and other writers like will no longer be available.

SOURCE and LINKS
Turkey's Hurryiyet Daily News
Telegraph story
Nature editorial
Reason.com

Fewer moose on the loose: Climate change is taking a toll on Minnesota's moose population, putting them in line to be added to the state's species with special concerns list.
Fewer moose on the loose: Climate change is taking a toll on Minnesota's moose population, putting them in line to be added to the state's species with special concerns list.Courtesy USDA Forest Service
While it's been a pretty good 16 years for Minnesota wolves and bald eagles, that's not been the case for moose. The behemoths will likely be moving on to the state's list of species with special concerns, according to the Minnesota Department of Natural Resources. In total, 67 animals and 114 plants are being proposed to be added to the lists while 15 plants and 14 animals – including wolves and bald eagles – have rebounded in numbers to be removed from the designations. Climate change is being credited as the big threat to Minnesota's moose population.

...And these beautiful close-up photos of human eyes by photographer Suren Manvelyan show it. The Smithsonian.com post also includes some of the science behind the human eye.

More of these remarkable photos can be found at Manvelyan's website.

Claude the alligator
Claude the alligatorCourtesy Chris Pederick
Sensory organs dotting the heads of members of the crocodilian family show evidence of being more sensitive to touch than even human finger tips. Some of the literally thousands of minute pigmented bumps, called Integumentary sensory organs ( ISOs) covering the reptiles' tough, armored skin are used to detect surface ripples or water movement for determining prey location. But many of the remaining receptors can detect the slightest touch from potential prey, and cause a croc's or gator's jaws to snap shut with lightning speed. The study was done by researcher Duncan Leitch and biologist Kenneth Catania, and appears in the Journal of Experimental Biology.

MORE INFO
Story at ScienceDaily.com.

Sep
26
2012

Dead zombie bee: Up to 80 percent of bee hives along the West Coast may be impacted by the "zombie bee" phenomenon. Parasite flies plants inside the bees, like this one, that ultimately kill them.
Dead zombie bee: Up to 80 percent of bee hives along the West Coast may be impacted by the "zombie bee" phenomenon. Parasite flies plants inside the bees, like this one, that ultimately kill them.Courtesy wintersixfour
Zombies are all the rage these days, and not just on cable TV shows or at pub crawls.

There's a growing trend in "zombie bees" working its way around the West Coast. Just this week beekeepers in Washington state report finding evidence of "zombification" of their bees.

The impacted bees get their name for their changing behaviors once they host the parasitic flies that cause the trouble. While most bees spend their nights nestled snuggling in a comb, these "zombie bees" actually go out flying in very erratic patterns. Like many other night bugs, the zombie bees fly to light and usually die quite soon.

What's really at play is that the tiny parasitic flies plant eggs into the host bee. Those eggs grow into maggots that eat the inside of the host bee that ultimately cause its demise.

Evidence of zombie bees was first found in 2008 near Sacramento, Calif., and beekeepers around the west coast have seeing the spread of the problem in the years since.

Researchers are trying to figure out if this parasite problem is a factor in the bee population declines that have been going on nationwide. One researcher has set up a website – ZombeeWatch.org – to allow amateur beekeepers to share information about zombie bees they are finding around their hives. It is also looking for people who want to step forward to be "zombee hunters."

There has been one isolated report of zombie bees in South Dakota. So far, two investigations in Minnesota have turned up no evidence of zombie bees.

Sep
10
2012

Sinocalliopteryx gigas: predator or scavenger?
Sinocalliopteryx gigas: predator or scavenger?Courtesy Illustration by Cheung Chungtat via PLoS ONE
The 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.

Jul
13
2012

Evolution timeline from 1882: This caricature of Darwin's theory appeared in the 1882 Punch Almanac. The recent evolution timeline created by Kyrk and Sezen is a bit of an improvement.
Evolution timeline from 1882: This caricature of Darwin's theory appeared in the 1882 Punch Almanac. The recent evolution timeline created by Kyrk and Sezen is a bit of an improvement.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?

SOURCES
Evolution Timeline

Twin Cities Naturalist
Twin Cities NaturalistCourtesy Twin Cities Naturalist
Lilacs are blooming, ospreys are returning to nests, spring continues to delight. Check out this week's Monday Phenology: Nature's Week in Review where professional naturalist Kirk Mona of Twin Cities Naturalist discusses what new nature observations were seen around the Twin Cities area in the past week.

Phenology is the science of the seasons. It looks at how and when nature changes according to seasonal climatic conditions.

View a summary of phenology sightings in the Twin Cities this past week.