Found a great post on the Flickr Blog this morning. Some guys in Oklahoma sent a Pentax camera into space on a balloon. Over 104,000 feet straight up, photographing all the way up and back down. They wrote software to model balloon flight dynamics and used weather data to predict where the balloon would travel; the camera and related gear landed about twelve miles from its launch point.
Tuesday, July 29, 2008
These videos are simultaneously so awesome and so campy that it hurts. You've been warned.
Large Haldron Rap
Daniel discovered these gems, but he didn't post them (?). He has totally been scooped!
Monday, July 28, 2008
What a great reaction! So when I received a similar reaction to Giardia lamblia this evening I knew it was time to blog.
See more images of giardia. (The scientific diagrams are especially cute looking.)
Giardia lamblia is a single celled organism. What we perceive as eyes are actually twin nuclei (spherical compartments that contain DNA) and the "mouth" is a parabasal body (don't ask).
This notably cute protozoan is responsible for giardiasis (better known as beaver fever and backpacker's diarrhea) and symptoms include "loss of appetite, lethargy, fever, explosive diarrhea, hematuria (blood in urine), loose or watery stool, stomach cramps, upset stomach, projectile vomiting (uncommon), bloating, flatulence, and burping (often sulphurous)." [Wikipedia] Giardia lamblia lives in the small intestine and spreads when infected fecal particles are able to contact food or water that will be ingested.
Friday, July 25, 2008
Tuesday, July 22, 2008
Nobody seems to know where this health myth originates, but it is not based on scientific evidence. For most people, having a drink when thirsty is enough to meet daily liquid requirements. Pushing oneself to drink additional water is not only unecessary, but can be damaging to your health. Water intoxication occurs in extreme cases and can result in altered mental states and death.
- Woman dies after taking part in "Hold Your Wee for a Wii" competition (a water drinking competition).
Monday, July 21, 2008
This is another of the illustrations I did for Don Prothero's book,"Evolution, What the Fossils Say and Why It Matters". The caption in the book reads... "The transformation from primitive synapsids like Ophiacodon and the fin-backed Dimetrodon to the predatory gorgonopsians to the weasel-like Thrinaxodon and finally to true mammals is one of the best transitional series in the entire fossil record."
The fossils of these animals were found and this transition took place from the early Permian period through the Paleozoic/Mesozoic extinctions to the Triassic.
Thylacine Dingo Comparison
Although we talk all the time of the incredible diversity of life on our planet, that diversity is really an amazing amount of variation on a relatively very few themes.
Here we have a recently extinct, marsupial Thylacine (3.) and its ecological equivalent (and replacement in Australia), the Dingo, a placental canine carnivore. These mammals have had separate evolutionary histories since at least the early Cretaceous. Both are the descendants of little insectivorous creatures that lived in the shadow of the dinosaurs. So are aardvarks and elephants, but in this case both these creatures evolved to do the same ecological task. And apparently the best functional form for a cursorial mammalian predator is “doggish”.
Seems that Carl doesn't have a change to update much, but he keeps a fabulous blog called "Dealing with the Beasts" under the pen name Olduvai George. Don't miss his flickr photostream.
- Found Carl via Visualizing Evolution.
Sunday, July 20, 2008
The fruit (also called pitaya) grow on long slender branches of the cactus around a woody trunk.
I have been growing this plant from seeds taken from the last dragon fruit that I ate. Most (if not all) of the seeds planted germinated, and this happened very fast. Keeping them moist, they continue to grow surprisingly quick.
What amuses me about these seedlings are their two cotyledons (seed leaves). Being a cactus of it's particular sort, these are the only leaves this plant will ever have - a nod to it's heritage as a dicot (one of the two major groups of flowering plants) much like our embryonic gill slits are a nod to ours.
It will be several years before these cacti are ready to produce large night-blooming flowers, and bear fruit.
Monday, July 14, 2008
Dr. David Goodsell makes exquisitely detailed to-scale watercolour and digital paintings of cells and the molecules of life.
The molecule featured in the image above is myosin, which was discussed a few posts back in "How Rigor Mortis Works".
His webpage is a little difficult to navigate, but worth your time for all the fantastic and colourful illustrations viewable there.
Saturday, July 12, 2008
Giant Golden Book of Biology - Illustrations by Charles Harper, originally uploaded by Grain Edit.com.
This beautiful little book from 1961 was designed to introduce children to biology. I just love the cute and stylish illustrations, which touch on the major concepts of a first year biology class.
In this image you can see a cnidarian, a pterophyte, a dinoflagellate and a member of hemiptera... to name a few!
Click to view more images of these great illustrations by Charley Harper.
Wouldn't it be grand to own a copy?
Friday, July 11, 2008
Smell plays an important role in who a fruit fly chooses for a mate. That's because fruit flies rely on smell to tell them the sex (male or female) of the other Drosophila they encounter.
Typically, when a male fly smells a female he will engage in sexual behaviour and approach her. She will reciprocate by engaging in correspondent female sexual behaviours. Why do they do this? Let's explore the genetic basis of sexual behaviour in Drosophila.
Fruit flies have a gene called the fruitless gene. The fruitless gene produces a protein called Fru. The Fru protein is expressed (that means that it's working in and on) areas of the antennal lobe, in particular - Fru works on brain cells (mAL neurons) located there. The fruitless gene is only expressed in male fruit flies. A fruit fly smells through it's antennal lobe.
Catch all that? The fruitless gene in fruit flies affects cells that process smell in Drosophila, but only in males. Smell is very important in mate selection and sexual behaviour.
So what exactly does fruitless do?
Early in development both males and females have the same number of mAL neurons in their antennal lobe. As both sexes develop, mAL neurons die. Mature females typically have 5 mAL neurons remaining and these have a female-specific shape. Mature males on the other hand, have 30 mAL neurons remaining and these have a male-specific-shape. Only male mAL neurons grow extensions that connect to the subesophageal ganglion, an area of Drosophila's brain that processes smell and initiates male sexual behaviour. These male differences are all due to the work of Fru.
In other words, the fruitless gene causes brain cells that process smell to connect to more brain cells that initiate male sexual behaviour in a fly.
So, what do you think will happen if the fruitless gene is turned on in a female fly? What do you think will happen if the fruitless gene mutates so that fru is not expressed in male flies?
- In the first case, the expression of fru will cause the female to develop mAL neurons like a typical male, and she will exhibit male sexual behaviour when she smells another female.
- In the second case, the lack of fru expression will cause the male to develop mAL neurons like a typical female, and he will exhibit female sexual behaviour when he meets up with another male.
I hope you guessed the correct answer! Fru may be expressed atypically in nature, as well as in the lab.
At this point you may be wondering what happens to the male sexual area of the subesophageal ganglion in female flies. It becomes a vestigial area. You may be surprised to learn that many female animals have vestigial brain areas that control male sexual behaviour, including most mammals. Hmmn!
So, we've learned that a single gene can control what sort of sexual behaviour a fruit fly exhibits - male typical or female typical. Isn't that neat?
Of course, human sexuality is far more complicated than Drosophila's! (And even Drosophila's is more complicated than described here. Other genes and mechanisms have important roles to play, as do environmental factors.) Experts agree (based on quite a lot of good evidence) that when it comes to humans, both biological and environmental factors play an important role in sexual preference. And the role these factors play in sexual orientation varies considerably between individuals.
All the same, it's not unlikely that similar mechanisms are at work in creating human sexual behaviour and researchers are on the hunt for our own copy of the Fruitless gene.
Fruitless gene - A gene studied in fruit flies that produces the protein Fru.
Fru - A protein that alters the development of mAL neurons in the antennal lobes of Drosophila.
Antennal lobe - For Drosophila, this is the first stop in processing smells. It is the rough equivalent of the olfactory bulb in humans.
Neuron - Cells of the nervous system are called neurons. When people talk about brain cells they usually mean neurons.
Subesophageal ganglion - An area of the fruit fly brain, part of which controls male sexual behaviour.
- Seattle Times: Born gay? How biology may drive sexual orientation.
- Nelson's "An Introduction to Behavioral Endocrinology" 3rd ed. p.209-213
Fruitless specifies sexually dimorphic neural circuitry in the Drosophila brain
Written for Homosecular Gaytheist in response to some comments on Reed's post on homosexuality in penguins. Unfortunately, some folks hope homosexuality is simply a product of lonliness, while others think that it's about aggression (and irresponsibly enough, feel quite confident asserting that scientists do too). Questions are welcome.
Wednesday, July 9, 2008
There's an incredible story to hear here, and the more you learn the weirder, scarier and more incredible it gets.
You may already know that this religion was founded by a science fiction writer, and that high ranked members believe that the insane souls of aliens cause all human suffering.
You may have already seen Tom Cruise in a cape.
But you may not know that this story includes:
- an internal secret service agency and a secret navy
- high suicide rates and high pressure abortions
- attempts to destroy critics through harassment, litigations and framing
- destroyed families and abandoned children
- 100,000,000 year labour contracts
- salvation that costs 350,000$
... rolled in with a historically unique fight with Anonymous - a group of unorganized geeks who read the same websites and who are raising awareness about Scientology, originally provoked by attacks from the church designed to shut down popular websites and destroy the lives of contributing critics.
The Church's Official Website
Scientology's Religious Freedom Watch Web Site (Warning: Intense, litigious and very bizarre.)
A former Scientologist Tory Christman's YouTube channel.
Xenu TV on YouTube
CNN interview with Scientologist Tommy Davis
Annonymous: Call to Action
Footage from a meeting of Scientologists, including Miscavige and Cruise
Tuesday, July 8, 2008
Spotted hyenas have a reputation for gross behaviour. No surprise since:
- They have a bone crushing bite which helps them to break up the skeletons of their prey, which they eat.
- They are an aggressive species. It is not unusual for new cubs to kill their siblings within hours of birth.
- recognizing trustworthiness
But Corcuta crocuta is most famous for it's unusual sex role and appearance reversals.
- Women rule. Females are larger and more aggressive. Even the lowest ranked female in the dominance hierarchy comes before the highest ranked male.
- Females have masculinized external genitalia that closely resembles the male genitalia and is capable of producing erections. This structure allows them to choose absolutely who they will and will not mate with. Amazingly, they even deliver young through this pseudopenis.
Males are less aggressive and more submissive, but in adulthood have higher levels of circulating androgens than female hyenas. Androgens are male hormones that are associated with aggression and dominance behaviour in mammals, including humans. We don't understand why females develop masculinized genitalia.
Some background: In most mammals (again, including humans) a fetus exposed to high androgen concentrations will develop male reproductive structures. Human women with congenital adrenal hyperplasia may have moderately to severely masculinized genetalia. Alternately, genetic males with faulty androgen receptors (AIS) can develop completely as females.
With this in mind, you might expect that female spotted hyenas are exposed to unusually high concentrations of androgens while in the womb and you would be correct. However, steps taken to block the effects of androgens on the developing fetus have no effect on the development of masculinized genitalia. For scientists, this is quite surprising and weird!
Just sayin' ...
The Paradoxical Predator
Who's Laughing Now?
Spotted Hyena @ Wikipedia
"All wings are airfoils, including those of planes." - Biology: Concepts & Connections
via Street Anatomy
ps. This guy's other art isn't sciencey, but it is pretty cool and view-worthy.
Monday, July 7, 2008
As Echinoderms, they are family of Starfish and Urchins. However they have their mouth on the upside, unlike their family members.
Crinoids are suspension feeders. With tiny tube feet on their arms they catch plankton and detritus, to be directed trough a central channel towards the mouth.
Over 500 distinct species are described. The earliest traces of those animals go back almost 500 million years!
Very generally, a muscle consists of bundles of muscle fibers and the nerves that excite them. Muscle fibers are very long cells that contain bundles of myofibrils. And myofibrils consist of repeating units called sarcomeres. Sarcomeres can contract, and when many sarcomeres contract simultaneously their muscle does too.
So, our nested units from largest to smallest are:
muscle > muscle fiber > myofibril > sarcomere
The contracile mechanism of a sarcomere consists of thin filaments and thick filaments. Thin filaments are made of a protein called actin and extend lengthwise into the sarcomere from either end. Thick filaments are made of a second protein, called myosin which also extends lengthwise in the space between the thin filaments.
This diagram will help you visualize the arrangement of the thin and thick filaments within a sarcomere. Thick filaments also have regions called "heads" depicted as circles in the diagram.
ATP is a high energy mollecule and is the molecular currency of energy transfer within a cell. When ATP interacts with a thick filament head it loses a phosphate group and energy is transferred from the ATP mollecule to the head, causing the head to extend into what is called it's "high energy position". The head will stay in it's "high energy position" until a message is send to the sarcomere telling it to contract. The message comes in the form of calcium ions.
When a nerve excites a muscle fiber a cascade sequence of events occur that lead to the release of calcium from compartments made of fatty membrane that surround myofibrils. Released calcium ions enter sacromeres and attach to the thin filaments causing them to change shape so that docking sites for the for the thick filament heads appear. The cascade continues as thick filament heads bind to these docking sites and undergo a change in shape that pulls on the thin filament bringing it closer to the center of the sarcomere. This act effectively shortens or contracts the muscle on a molecular level, and (as stated earlier) when many sarcomeres contract simultaneously their muscle does too.
The thick filament head is now in it's "low energy position" and will stay attached to the thin filament docking site until another ATP mollecule interacts with it, releasing it back into it's "high energy position". ATP also powers pumps that remove calcium ions from the sarcomere and place it back inside it's membrane bound compartment.
Two more pieces of background. 1. ATP is produced within a cell for use by that cell. 2. When a person dies ATP production comes to a halt, and cellular supplies are rapidly depleted.
From "Biology: Concepts and Connections"
If you haven't been bamboozled by all the new science jargon then you may have already guessed how this anatomical set-up results in the post-mortem condition known as rigor mortis (from Latin, meaning "stiff death").
Remember that in a relaxed muscle, thick filament heads are in their "high energy position" and are not bound to the thin filament. Unlike other molecules that expend the energy gained from ATP right away, the heads are waiting for calcium to arrive and unlock their docking sites.
Have you guessed now?
The membrane compartment that surrounds the myofibril decomposes before the sarcomeres that make up the myofibril do. No longer contained in it's membrane compartment, calcium ions may enter sarcomeres and unveil the docking sites for thick filament heads. The heads expend the energy that they acquired prior to death by binding to the thin filaments and sliding them towards the center of the sarcomere, contracting the sarcomere...
... and when many sarcomeres contract simultaneously their muscle does too, resulting in the disturbing twitches and gruesome postures of rigor mortis. Eventually the sarcomeres decompose too, muscles relax and rigor mortis comes to an end.
Muscle fiber - A muscle is a bundle of muscle fibers which are long, multinucleate cells that contains bundles of myofibrils.
Myofibril - Myofibrils are strands of repeating sarcomere units surrounded by a modified endoplasmic retriculum called the sarcoplasmic retriculum which acts as a calcium sequestering compartment.
Sarcomere - Are the fundamental contractile units of muscles consisting of thin and thick filaments. The thick filaments have heads that pull the thin filament to the center of the sarcomere, contracting it.
ATP - Adenosine triphosphate, the molecular energy currency of cells. When it loses a phosphate group and becomes ADP (adenosine diphosphate) energy is transferred.
Protein - Proteins are long chains of amino acids which form a diverse group of mollecules. Proteins carry out a wide array of functions and can be thought of as the mollecular machinery of cells.
Thick filament - Made of myosin, the thick filament has portions called "heads" which can attach to the thin filament and pull it towards the center of a sarcomere.
Thin filament - Made of actin, the thin filament protrudes from either end of the sarcomere. When calcium binds to the thin filament docking sites for the thick filament heads are revelealed which they may bind to causing contraction.
Friday, July 4, 2008
The carnivorous aquatic plant Utricularia produces those curious organs which are bags it uses to trap small animals and digest them...
Ultricularia (aka bladderwort) on Wikipedia