Darwin 200

Happy anniversary Charles Robert Darwin. This year, 2009, celebrates 200 years since his birth and 150 years since he published his revolutionary book: On the Origin of Species by Means of Natural Selection.
There are hundreds of websites that celebrate the life and work of Charles Darwin. Some of the best include:
The Natural History Museum's Darwin 200 website.
The journal Science has a cool blog about Darwin and evolution.
And the complete works of Charles Darwin is accessible online here.

Snowflakes

Every schoolchild learns that no two snowflakes are identical. But how do you see snowflakes up close? It's not as easy as you might think. The first problem to overcome is capturing your flakes, or harder still, making your own. Then you have to light and magnify them without any melting, and finally take a photo without your lens misting up.

Luckily, there are some handy tutorials on the web and probably the best place to visit is this one from physics professor and snowflake photography expert Kenneth Libbrecht at the California Institute of Technology.

The key thing, apart from a good camera-microscope setup, is to work fast, before the flake melts, and to work cold. Dr Libbrecht recommends a working temperature of around-15 degrees C...yes that's minus 15!

The result is a series of photographs that reveal the miniature beauty of the snowflake.

But even if you manage to capture, magnify and photograph snowflakes successfully, you will still have to wade through hundreds, if not thousands of flakes as most flakes are misshapen and unsymmetrical in shape. 

Professor Libbrecht's snowflakes website offers more tips on how to make your own crystals and, amazingly, how to preserve them as snowflake fossils. 

Nature's Most Extreme Animal

It may not be the most exciting looking animal in the world, but tardigrades, or the water bear as it is commonly known, is a fascinating creature that exhibits some truly remarkable abilities.
These tiny animals, closely related to arthropods (insects, spiders and crustaceans) measure between 0.1 - 1.0 millimetres in length and live in oceans, ponds, lakes, puddles, just about anywhere that accumulates water. One of the amazing things it can do is withstand drought by transforming itself into a dehydrated capsule, a state known as cryptobiosis. During this state, all the creature’s metabolic processes reduce to a tiny trickle and a sugar, trehalose, replaces lost water. In all effects, the creature is practically dead. But, upon rehydration on contact with water, tardigrades carries on about its business as normal.
One report claims to have revived a tardigrades that had been in a dormant state for over 120 years, although this is largely discredited. Most evidence suggest they can remain in this state for up to ten years in some species.
Tardigrades can also survive exposure to extreme temperature (from –200 degrees C up to 151 degrees C). A recent experiment taking tardigrades into space, showed that they can withstand the cosmic radiation and vacuum of space travel. Although many did suffer UV radiation.

A truly amazing animal.

Circle of Confusion

It is always fun to present images that make the viewer scratch their heads and take a second look. The picture above could resemble mosaic tiles on a bathroom wall, or the close-up pixels of a digital photo. In actual fact the image is on a completely different scale. These are meadows and fields as seen by the Landsat-7 satellite, orbiting 705 kilometres above Earth.
What appear to be tiny circular dots in the image, are actually fields of crops. The circular plots contain crop plants that are irrigated by a long metal sprinkler, often 400 metres in length, that is anchored at the centre, and pivots around the entire field. The result for an aerial photographer or satellite is a distinctive pattern of dots, typical to farming areas such as Kansas and Idaho in the USA. The Landsat-7 satellite can see the Earth using a wide spectrum of visible light and non-visible light sensors. For example, its infrared sensor can detect areas with high moisture content, which reflects infrared radiation. In the Landsat image above, red dots represent infrared reflecting areas and correspond to plots that are actively being irrigated. Brownish circles are fields left to fallow and green circles are meadows and pastures.

Nature's Deadly Machines

Most viruses are so small that visible light waves are not fine enough to capture their image, so scientists use electron microscopes, x-rays and other methods that have a much finer resolution than light microscopes. Recent advances in computer power and software technology have enabled scientists to combine computing power with the large amounts of data generated by these high resolution microscopes. The results are impressively visual three dimensional computer models of viruses. These models can be coloured, magnified, rotated and dissected in a myriad of combinations. By understanding the structure of viruses, scientists are hoping the knowledge will lead to new drugs and therapies for the diseases that viruses cause.

The image shown here is of the bacteriophage known as P22. It was created by Gabriel Lander from the Scripps Research Institute, using a technique known as cryo-electron microscopy, a technique that involves preserving the virus at extremely cold temperatures while electrons are fired all around it to obtain 3-D data. The outer shell that coats the P22 phage has been removed to reveal the tightly coiled DNA within (green). At the base, is a miniature molecular motor (red and purple) known as a portal. This portal powers the injection of virus DNA into its host.

Body Scanning

This image was produced using a multi-slice CT (computed tomography) scanner, which uses a thin X-ray beam to scan around the patient collecting data from different angles to form digital 'slices' of the body. A computer reconstructs the slices into coloured three-dimensional images of bones and soft tissue. A contrast agent injected into the bloodstream allows blood vessels to be detected. This image was created with OsiriX medical imaging software which allows surgeons to navigate around the body using fly-through animations of the data. Recent machines built by Philips and Toshiba are set to produce scans with even finer detail and resolution, with faster scanning times and smaller x-ray dosage for patients.

The Genetic Timebomb

The image here, produced by the excellent Hybrid Medical Animation, shows a chromosome with highlighted telomeres – the region of DNA found at the end of a chromosome. Telomeres act as a buffer and protect the cell from dividing too many times. Every time the cell divides, the telomeres shorten until they reach certain point when they instruct the cell to cease further cell division. In red blood cells for example, we start off with roughly 8,000 base pairs at birth, to 3,000 base pairs as we age, ending with a figure as low as 1,500 in elderly people.
If the telomeres did not do their job, cells would continue to divide causing genetic damage, cancer and other diseases. The chemical responsible for building telomeres is an enzyme called telomerase. During normal cell division, telomerase dwindles, each time building less telomere material. In many types of cancer, telomerase does not dwindle, it keeps instructing the cell to rebuild the telomeres and hence continually divide, effectively making the cell immortal. Scientists are hoping to target this mechanism in the hope that it will lead to a new therapy to treat cancer. Telomere length is also suspected by some to be involved in the ageing process. Some even believe that measuring telomere length could predict mortality.

One theory even states that telomere lengths shorten with each generation, eventually leading to species extinction. The so-called genetic timebomb.