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Strongest fibre in the world—spider silk

Weight for weight, spider silk is stronger than steel. Indeed it is the strongest fibre in the world—so strong that bullet proof vests, body armour, artificial ligaments, super-strong wound dressings, replacement tendons, parachute cords and many other materials can be made from it.

Darwin’s bark spider found in the jungles of Madagascar produces the largest webs known and its silk is 10 times stronger than Kevlar. Kevlar is a synthetic material which is five times stronger than steel on an equal weight basis. Three different approaches are being explored to make such materials in large quantities. The first is to make synthetic materials resembling natural spider silk. A second approach is to prepare genetically modified silk worms that can produce spider silk in large quantities. An advantage of this approach is that each silk worm can produce about half a mile of silk, and since it is already spun, there is no purification necessary. A third approach is to genetically modify goats so that special milk proteins are produced. These can then be purified and spun into a material resembling spider silk.

Parts of the DNA of spiders were inserted into the DNA of silk worms by US scientists, working at Kraig Biocraft Laboratories Inc. Such ‘transgenic’ silk worms could then produce silk that had many characteristics of spider silk. It is expected that this new type of silk will be commercially available within a year, and find a variety of applications for civil and military use.

http://www.popsci.com/node /48816/?cmpid=enews100710 http://www.wired.com/wiredscience/2010/09/super-strong-spider-silk/

Test tube babies—from a selection

Test tube babies are made by uniting the egg from a woman with the sperm of a man in a lab dish. The egg then starts dividing and the early stage embryo is then transferred into a woman’s uterus to develop. The technique is known as In Vitro Fertilisation (IVF). Some clinics, in order to increase the chance of success, implant more than one embryo into the uterus, resulting in the birth of twins, triplets, quadruplets, etc. These babies are often born early and they can face health problems. Scientists have therefore been searching for methods whereby they could select the best embryos for implantation.

Now Renee Reijo Pera and co-workers at Stanford University have developed a new test that allows the best embryos to be picked up for transplantation. An exclusive license has been acquired by a US company, Auxogyn, to commercialise the findings. In the US alone there are some 500 companies offering IVF services and the total world market is estimated to be several million dollars.

Meanwhile, the Nobel Committee announced on October 4, 2010 that this year’s Nobel Prize for Medicine will go to Bob Edwards, an 85-year-old British scientist who pioneered this method. The researches were carried out at Cambridge University and the first ‘test tube baby’ Louise Brown was born in northwest England by this procedure on July 25 1978. Since then some four million babies have been born by IVF.

Human evolution due to dinosaur extinction

About every 100 million years, our planet is hit by a big asteroid which can change the course of evolution. If we were to be hit by such an asteroid now, most of life as we know it would be wiped out and the few insects, fish and bacteria/viruses that survive would begin the evolutionary process all over again.

About 200 million years ago the lush green earth was inhabited by reptiles, many of which, such as the dinosaurs, were huge in size. This reptilian era lasted some 160 million years. Then 65.5 million years ago a huge asteroid, about 10 kilometres across, slammed into Mexico. The result was a global catastrophe. The blasted rock layers released a huge amount of carbon and sulphur containing gases. Fires raged and darkness descended as the resulting dust blocked sunlight from reaching the earth. Acid rains followed and the earth cooled. Most life was wiped out, including reptiles, birds and plants and only about half of the most resilient mammals survived. The extinction of the dinosaurs and many other life forms changed the course of evolution.

The surviving mammals were generally smaller in size, versatile in their movements, could breed fast, and escape the fires and acid rain that ravaged the earth. There was a new burst of evolutionary creativity in this changed environment some 10 million years later, finally leading to humans, as is evident from the ‘molecular clock’ studies which are based on the reconstruction of the evolutionary tree from the study of the genomes of related species.

We may owe our civilisation to the extinction of the dinosaurs! http://www. newscientist.com/article/mg 20727796.100-cosmic-accidents-killer-asteroid-with-a-silver-lining.html aurahman786@gmail.com