Does Dinosaur DNA still exist? - Part II

Iron saved soft tissue in Dinosaur fossils?

The iron nanoparticles, however, may be doing more than just preserving tissues.

Despite what happens in the science fiction world of “Jurassic Park”, no dinosaur DNA has yet been found. The reason for this is that DNA is thought to have a half-life of 521 years, so what could be left after the 65 million years or so that stand between humanity and dinosaurs? But could the iron-based preservation process might allow DNA to bypass its typical half-life and last a lot longer.

To find that out, Dr Schweitzer and the team used an iron-removal compound to delicately pull iron away from the dinosaur tissues without damaging them. They then added four different stains that react only with either DNA itself, or with proteins closely associated with it in organisms other than microbes. Remarkably, in all cases, these specific stains lit up inside the ancient cells in the tissue samples. This hints that something chemically very similar to DNA can remain in a fossil and might yet be hidden precisely where it had resided during life.

As to whether any DNA strands can ever be read remains to be determined because of the complex knots that they have been tied into by the iron. But Dr Schweitzer and Dr Goodwin plan to try. Many things other than iron tie proteins into knots. One is sugar which, when exposed to tissues in high enough concentrations, can also cause abnormal bonds to form. This process damages tissues in diabetics. Some doctors suspect the process might be reversible by using drugs, like N-phenacylthiazolium bromide, that selectively cleave abnormal bonds while leaving normal ones alone. With this in mind, the researchers are considering trying some of these drugs on their dinosaur proteins to see if they can untangle them.

In the end, such tactics will not be quite as poetic as Hollywood’s notion of collecting dinosaur DNA from bloodsucking mosquitoes preserved in tree sap. But if it results in sequencing even part of the genes of a T. rex to determine more about these and other prehistoric animals, then no one is going to mind.

Source: The Economist

Does Dinosaur DNA still exist? -Part I

Iron from haemoglobin saved soft tissue in Dinosaur fossils?

As you know, fossils are actually a replica of the tissue once buried. So how can it be that scientist now find traces of soft tissue in the fossils?

When most animals die, nature likes to tidy up by making their bodies disappear. Very occasionally, though, the destructive processes get disrupted. This usually happens when the corpse is quickly buried by sediment deposited by a river or blown in by the wind. Then begins a slow process in which minerals precipitate from groundwater into the encased organic material, eventually replacing it with a stony replica: a fossil.

In recent years traces of soft tissue, such as blood vessels and bone cells, have been found in some dinosaur fossils. Now researchers have come up with an explanation for how these tissues were preserved for millions of years, which just might make it possible to extract some elements of prehistoric DNA.

 

 

In 2005 Mary Schweitzer, a palaeobiologist at North Carolina State University, found something unusual from a fossilised piece of Tyrannosaurus rex bone. Left behind were some fibrous tissue, transparent blood vessels and cells. Many argued that this material must have come from modern bacteria and not a T. rex, since nothing organic could possibly survive the 68 million years since the creature had walked the Earth.

 

 
In 2012, however, Dr Schweitzer and her colleagues went a step further, revealing the presence of proteins in a dinosaur fossil that had been freshly dug up and carefully protected from any potential contamination.

 

Moreover, one of the proteins the researchers identified could be found only in birds. Since dinosaurs were the ancestors of modern birds, the discovery made it hard to argue that soft-tissue material in the fossil could have come from bacterial contamination. Still, many scientists wondered how such a thing was possible.

 

Dr Schweitzer and her colleagues collaborated with a team led by Mark Goodwin, at the University of California, Berkeley, to seek an explanation. When sudiyng organic material from dinosaur with micro x-ray absorption spectroscopy, they notice something remarkable. The organic material in the samples was thickly laced with iron nanoparticles. In animals, iron is most commonly found in blood and this led the researchers to wonder if the iron had come from blood cells that had once flowed through their dinosaur’s veins.

 

Could this iron have played a part in the preservation of the tissues?

 

The researchers designed an experiment using freshly slaughtered ostriches which seemed to be a reasonable modern equivalent to dinosaurs. They extracted blood vessels from the bones of the birds and soaked them in a haemoglobin solution obtained from ruptured ostrich blood cells for 24 hours.

The samples were then placed in both a saline solution and sterile distilled water. As a control, some of the blood vessels were put straight into saline solution or water without being pre-soaked in blood.

 

As expected, the ostrich tissues that went directly into the water and the saline solution fell apart rapidly and were entirely consumed by bacteria or heavily degraded in just three days. The same thing happened to the tissue soaked in haemoglobin and placed in water.

But the treated sample in the saline solution remained intact and has stayed that way for two years now, with no signs of bacterial growth.

 

Dr Schweitzer and Dr Goodwin believe that highly reactive ions known as free radicals, produced by iron as it is released from the haemoglobin, interact with the organic tissue causing abnormal chemical bonds to form. These bonds effectively tie proteins in knots at the molecular level, much as the preservative formaldehyde does. This knot-tying makes the proteins unrecognisable to the sorts of bacteria that would normally consume them. This, they theorise, is how the soft tissues manage to survive for millions of years without rotting away.

 

Stratification threatens the Arctic Ocean's recycling system

Stratification threatens the Arctic Ocean recycling system by suppressing the vertical movement of water. And global warming encourages stratification because it turns the ice into a layer of fresh water that sits on the surface. (You can read more about it in my older posts covering the strength of the Gulf Stream) .

The Arctic Ocean’s ice sheet covers in 2012 half the Area it used to cover in 1979. This is causing alarms among the environmental organisations and hope for those who want to gain access to new natural resources and new sea routes. Some people hope for a fishing bonanza, but they may be disappointed.
 

The waters around the Arctic account for a fifth of the world’s catch. The ice melt might lead to too much change to the eco systems and decrease productivity. But how can this be? As the ice melts, more light can reach the water, and that means more photosynthesis by marine algae supporting, directly or indirectly, the fish and mammals that live in the Arctic Ocean.

The most important reason why the ice melt might decrease productivity in the Ocean is that global warming may increase ocean stratification. Stratification is the tendency of seawater to separate into layers, because fresh water is lighter than salt and cold water heavier than warm. The more stratified water is, the less nutrients in it move around.

Most free-swimming sea creatures are pelagic. When they die, all these organisms sink to the bottom, where they become food for benthic creatures. Once they have been consumed their component molecules, including nutrients such as nitrates, phosphates and iron, are stuck in Davy Jones’s locker. For the surface to be productive, the locker must be opened and the nutrients lifted back up, so that they can feed the growth of phytoplankton.

One of the most important ways this happens is by upwellings of water from the bottom—great churning columns caused by the collision of cold and temperate waters. Two of the most important are in the Arctic: south of Greenland on the Atlantic side and south of the Bering Strait on the Pacific side. Nitrates are abundant at the surface in both places, which is why they are among the world’s richest fishing grounds. There are few upwellings in the tropics, which are thus nutrient-poor.

Stratification threatens this recycling system by suppressing the vertical movement of water. And global warming encourages stratification because it turns the ice into a layer of fresh water that sits on the surface.

Parts of the Arctic seem to be getting badly stratified. In winter, there is almost no density difference in the North Atlantic and the Barents Sea—as you would expect given the upwelling there. But in summer, the northern part of the Barents Sea is even more stratified than the tropical Atlantic and Pacific. And the Beaufort Sea’s stratification is high in both summer and winter.

A warming Arctic will not, in other words, be full of fish. It will simply be an ice-free version of the desert it already is

Source: The Economist

If the whole World had U.S average weight

If every country in the world had the same weight distribution as in the U.S., it would mean an increase in biomass of 20%. Or expressed more simple If the whole world had the same weight distribution as in the U.S., it would mean a body mass equivalent to an additional 1 billion people with a normal BMI.

Large parts of the world is moving in the same direction as the United States. If it becomes real, we will erode hard on the earth's food and nutrition resources, although the total amount of people possibly will decrease.


Source: BMC Public Health

10 ways to become tired and fat - 10

10. Avoid physical activity.

When you move you body, glucose and fatty acids are released as fuel and hunger signals are attenuated. Increased body temperature leads to reduced appetite. By not moving your body you help the body to store fat.