Sunday 17 April 2016

Archaeopteryx- a Bird like no other.



Archaeopteryx lithographica is a fossil originally unearthed in Germany in 1861, before being donated to the Natural History museum of London where it remains to this day. During the period of its discovery, the scientific thinkers of the time with the great fortune to be allowed access to such as specimen were baffled as to what exactly it was; which is very understandable as it is a very strange fossil indeed. 

“We know, on the authority of professor Owen, that a strange bird, the Archeopteryx, with a long lizard-like tail, bearing a pair of feathers on each joint, and with its wings furnished with two free claws, has been discovered in the oolitic slates of Solnhofen. Hardly any recent discovery shows more forcibly than this how little we as yet know of the former inhabitants of the world.” 

-Charles Darwin in "On the Origin of Species"

On the face of it, it appears to be some kind of bird. Close examination shows it to have impressions of feathers on its limbs, hollow bones that create a light body useful for bird flight, a furcula (wish bone), and finger bones that have been reduced and fused much like what is seen in the limbs of birds today. However, other characteristics are also seen that are definitely not common place among modern avian fauna. Teeth for example are visible in Archaeopteryx's mouth, rather than the avian keratinised beak. It had claws jutting out of its wings, and had no keeled sternum; the thick extension of bone on a birds chest that anchors muscles for flight.  A pygostyle was also missing from the fossil (fused, shortened tail bone), replaced with a long extended tailbone much like what is seen in dinosaurs. It has also been shown to have had scaled skin, again like dinosaurs. 

Since this initial discovery of an almost complete archaeopteryx fossil, many more have been discovered in geological strata around the world, providing greater insights into what exactly this fossil animal is, and what it was like as a living organism. What has been shown, and has now been widely accepted by the majority of the scientific community, is that this organism is an ancient ancestor of modern birds descended from reptiles, existed during the jurassic period 150 million years ago, and looked much like this (left); a dinosaur with feathers. Its feathers, although smothering the body, probably did not enable flight, but rather the ability to glide from great heights. These feathers were also likely used for camouflage from predators, as well as for display when mating. 

The archaeopteryx fossil is considered one of the most important paleontological discoveries of all time, as it provides a fantastic example of a transitional form; an ancient organism evolving from one particular type of animal to another, from dinosaur to bird. In the scientific community this is considered truly ground-breaking, however in creationist circles it is ridiculed, mocked, and made out to be a lie due to the fact that its existence goes against the unproven hypothesis that God created everything in its modern form. However, as has been proven again and again over the centuries through education, logical thought, the testing of ideas through experimentation, and the peer review of said ideas through the approach known as the scientific method, it is clear that this is not how life works in the slightest. And the discovery of a growing number of these fossils have come a long way in proving this fact.

-Thomas Glen
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Tuesday 5 April 2016

CRISPR - A brand new technology that could change the world.


Crispr (Clustered regularly-interspaced short palindromic repeats) is a revolutionary new biotechnology that allows particular segments of DNA to be modified or removed entirely, in an apparently cheap, fast, and easy way; especially in comparison to gene editing technologies that have existed before it.




How does it work?

Crispr technology is based on the evolutionary defence strategies of a bacterium known as Streptococcus Pyogenes. This bacterium, as a way to defending itself against viruses that attempt to use it as a host for its own DNA to reproduce, is able to attach itself to the viruses own DNA (using RNA as a guide to specific areas of its genetic code), and cleave or cut the DNA with the use of cas9 endonuclease (an enzyme molecule that breaks apart DNA strands).

Because of this bacterium, researchers are able to incorporate Cas9 endonuclease, and RNA into a living cell; the cell now able to be guided to a specific area of a gene, and cut, remove, and/or modify a particular segment. It could also replace a cut piece of DNA with an entirely new DNA replacement.

Why is this important?



The ability to modify or remove/add genes to DNA strands can have major connotations in the field of gene therapy. You could for example remove a gene in a persons DNA that would have later on developed into a form of cancer, or neurodegenerative disease. Or add a gene to the DNA where one is missing due to a birth defect. 

Of course this technology is very new, and due to ethical concerns may not be used in the field of human treatments for years to come. But looking at the incredible results it is achieving so far (link below on HIV treatment with crispr) it could develop into a very important technology indeed.

-Thomas Glen

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Images: Not my own