'Living fossil' coelacanth genome sequenced

Researchers sequenced the genome of the coelacanth: a deep-sea fish that closely resembles its ancestors, which lived at least 300 million years ago.

The study found that some of the animal's genes evolved very slowly, giving it its primitive appearance.

The work also shed light on how the fish was related to the first land-based animals.

The coelacanth has four large, fleshy fins, which some scientists believe could have been the predecessors of limbs.

It had been suggested that this fish was closely related to early tetrapods - the first creatures to drag themselves out of the ocean, giving rise to life on land.

But the study, published in the journal Nature, suggested that another fish called the lungfish, which also has four limbs, had more genes in common with land-based animals.

The coelacanth can reach up to 2m-long and is found lurking in caves deep beneath the waves.

It was thought to have been extinct for millions of years, until it turned up in a trawlerman's net off the coast of Africa in 1938.

Its ancient appearance has earned it the title "living fossil" - but it is so elusive, that it has been hard to study.

To find out more, an international team of researchers sequenced the coelacanth's genome, which contained nearly three billion DNA bases,according to the BBC.

Professor Kerstin Lindblad-Toh, from the University of Uppsala in Sweden and the Broad Institute of MIT and Harvard in the US, said: "What we can see is that while the genome as whole changes, the protein-coding genes - that make the living fish - are much more stable and much more unchanging.

"And if you think about it, this might be correlated to the fact that the coelacanth lives in a rather extreme and stable environment.

"It lives several hundred metres down in the ocean, and it may also be in an environment where it doesn't have a lot of competitors. So maybe it adapted to that environment a long time ago and it doesn't have a huge need for change."

The researchers also used the study to try and solve the long-standing question of whether the first tetrapods were more closely related to the coelacanth or the lungfish.

 

They compared DNA profiles of both of these fish with modern land-based animals, including mammals, birds and lizards.

"We selected 251 genes that were very similar in all these genomes so we could build this picture of how closely related these species were," Prof Lindblad-Toh explained.

This study is not the only one attempting to understand the coelacanth.

Since the fish was rediscovered in the 1930s, only a few hundred have ever been found, many of these dead caught up in trawls.

Scientists from the French organisation Andromede Oceanology are working with the Natural History Museum in Paris to attach acoustic tracking devices to the fish in order to study their behavior and capture 3D moving images of their fins as they swim.

R.Sawas

1st Phase of Integrated Environmental Management Project of al -Abrash River Reviewed

DAMASCUS, (ST) - A meeting was held here recently between the Ministry of State for Environmental Affairs and the General Commission for Remote Sensing. Participants reviewed the final results of the first phase of the monitoring project and integrated environmental management of al- Abrash River, which involved a general study of the project area and research materials, its methods and its stages.

Project supervisor from the General Commission for Remote Sensing, Dr. Ahmad Yaghi, pointed out to the recommendations and proposals that were made to address the environmental problems that al -Abrash River was afflicted, according to the Memorandum of Cooperation between the Ministry of State for Environmental Affairs and the Commission for Remote Sensing which includes scientific and technical cooperation in the fiel of environmental work at the national level.

Minister of State for Environmental Affairs, Dr. NaziraSarkis, confirmed importance of the participatory action among all national bodies in order to reach the desired outcomes that contribute to improving environmental work, indicating that the project aims to identify environmental problems that afflict al- Abrash River in Tartous and take the necessary actions to solve them in addition to benefiting from the National expertise to reduce pollutants in all its forms.

The minister pointed out that the work is in progress and the Ministry of the Environment is following up all issues and environmental problems and that the ministry continues to work in spite of all the hard circumstances in Syria.

For his part, Director General of the General Commission for Remote Sensing, Dr. Osama Ammar, underlined the integrity of the work and true partnership with the Ministry of Environment through the exchange of experiences between the two parties to improve the environmental situation, calling for appropriate action to reduce pollution at al –Abrash River.

It is worthy noted that the Ministry of Environment and the General Commission for Remote Sensing are carrying out many environmental projects and studies, including the Environmental National a Observatory and Integrated Environmental Management Project of the Northern and the Southern Great Rivers and an environmental integrated study of land use in some governorates as well as training of personnel in the Directorates  of Environment to establish an environmental databank and other projects.

Sh. Kh.

Deadly Effects of Certain Kinds of Household Air Pollution

Almost four million people die each year from household air pollution (HAP) caused by exposure to the combustion of biomass fuels (wood, charcoal, crop residues, and dung), kerosene, or coal. These individuals are among the tens of millions who rely on such products to cook their meals, heat their rooms, and light their homes. Those in lower and middle income countries are among the hardest hit by the effects of HAP exposure, which also causes childhood respiratory infection, chronic lung disease, and cardiovascular disease. Exposure to biomass fuel is associated with low birth weight, asthma, and tuberculosis.

Given these effects, the large populations at risk, and a growing global interest in lower-cost energy sources, researchers from three continents have published a comprehensive overview of the current approaches to HAP assessments, the aims of biomarker development, and the state of development of tests which have the potential for rapid transition from the lab bench to field use. The effort is being led by William J. Martin II, MD, Associate Director for Disease Prevention and Health Promotion, and health institutions, their findings are addressed in the article, "Household air pollution: a call for studies into biomarkers of exposure and predictors of respiratory disease," which is published online by the American Journal of Physiology-Lung Cellular and Molecular Physiology.

Current approaches to HAP assessment, challenges

The researchers found that current HAP assessment tools include direct quantitative measurement of products of incomplete combustion, as well as qualitative methods (including use of questionnaires or the categorization of HAP exposure by type). However, direct exposure assessments via personal monitoring are problematic due to the size, portability and recording capacity of equipment, and acceptability to the user.

Despite the new devices currently being field tested and scaled up for commercial use to address these concerns, specific particulate measurement alone cannot differentiate between the multiple sources of pollution such as mixtures of HAP, tobacco smoke, and outdoor pollution. "The grand challenge to the research community is to produce simple and validated tests that better identify populations that are at risk from HAP, and individual responses to exposure reduction strategies," according to Dr. Martin.

The researchers also found that current HAP exposure measurement methods are expensive, technically challenging, difficult to use with large population studies, and have substantial limitations, making an urgent case for the development of biomarkers of both exposure and health effects. These findings have led to their call for studies into biomarkers of exposure and predictors of respiratory disease.

Martin and his colleagues note that further development of biomarkers of susceptibility and effect could facilitate large scale studies examining the impact of HAP on health and disease in human populations. In the end, new biomarkers would: (a) improve epidemiological accuracy in association studies with health effect; (b) reduce the cost and complexity of monitoring intervention studies; (c) provide data for educating the public and policymakers about risk; and (d) inform clinicians and the public health community about human environmental exposures that are not well characterized.

Source: sciencedaily

B.N

How much gold is there in the world?

Imagine if you were a super-villain who had taken control of all the world's gold, and had decided to melt it down to make a cube. How big would it be? Hundreds of metres cubed, thousands even?

Actually, it's unlikely to be anything like that size.

Warren Buffet, one of the world's richest investors, says the total amount of gold in the world - the gold above ground, that is - could fit into a cube with sides of just 20m (67ft).

But is that all there is? And if so, how do we know?

A figure that is widely used by investors comes from Thompson Reuters GFMS, which produces an annual gold survey.

Their latest figure for all the gold in the world is 171,300 tonnes - which is almost exactly the same as the amount in our super-villain's imaginary cube.

A cube made of 171,300 tonnes would be about 20.7m (68ft) on each side. Or to put it another way, it would reach to 9.8m above ground level if exactly covering Wimbledon Centre Court.

But not everyone agrees with the GFMS figures.

Estimates range from 155,244 tonnes, marginally less than the GFMS figure, to about 16 times that amount - 2.5 million tonnes.

That bigger figure would make a cube of sides 50m (166ft) long, or a column of gold towering 143m above Wimbledon centre court.

Part of the reason is that gold has been mined for a very long time - more than 6,000 years, according to gold historian Timothy Green.

Continue reading the main story          

 All the gold that has been mined throughout history is still in existence ”

The first gold coins were minted in about 550 BC under King Croesus of Lydia - a province in modern-day Turkey - and quickly became accepted payment for merchants and mercenary soldiers around the Mediterranean.

Up until 1492, the year Columbus sailed to America, GFMS estimates that 12,780 tonnes had been extracted.

But one investor who looked at the research done in this area, James Turk, the founder of Gold Money, discovered what he regarded as a series of over-estimates.

 

He believes that the primitive mining techniques used up to the Middle Ages mean that this figure is much too high, and that a more realistic total is just 297 tonnes.

His figure for the overall amount of gold in the world is 155,244 tonnes - 16,056 tonnes, or 10% less, than the assessment by Thompson Reuters GFMS. A relatively small disparity, perhaps, but one that at today's prices comes to more than $950bn.

His conclusions are accepted by some investors but such is the feeling between rival analysts that one competitor described Turk's figures as an alternative to the GFMS's "in the same way that Jedi is an alternative to Christianity".

But there are others who think both sets of figures are too low.

One of Tutenkhamen's sarcophagi

"In Tutankhamen's tomb alone they found that his coffin was made from 1.5 tonnes of gold, so imagine the gold that was found in the other tombs that were ransacked before records were taken of them," says Jan Skoyles of gold investment firm The Real Asset Company.

While James Turk makes only minor adjustments to the GFMS figure for the amount of gold mined after 1492, Skoyles points out that even today China is "not particularly open" about how much gold it is mining.

And in some countries, such as Colombia, "there's a lot of illegal mining going on", she says.

She doesn't have an exact figure to offer, but one organisation that has tried to do some maths is the Gold Standard Institute.

Gold mine in Bunia There is much gold still in the ground, like here in Democratic Republic of Congo

Its experts believe that if we emptied our bank vaults and jewellery boxes, we'd find no less than 2.5 million tonnes of gold - though they admit that the evidence is somewhat sparse and the figure is a bit speculative.

In the end, all these numbers are made up of estimates added to estimates added to yet more estimates. Maybe they're all way off.

The good news is that we are not likely to run out of gold any time soon. The US Geological Survey estimates there are 52,000 tonnes of minable gold still in the ground and more is likely to be discovered.

"All the gold that has been mined throughout history is still in existence in the above-ground stock. That means that if you have a gold watch, some of the gold in that watch could have been mined by the Romans 2,000 years ago," says James Turk.

The way gold is being used in the technology industry, however, is different.

 

The British Geological Survey states that about 12% of current world gold production finds its way to this sector, where it is often used in such small quantities, in each individual product, that it may no longer be economical to recycle it.

In short, gold may be being "consumed" for the first time.

Source:BBC

R.Sawas

First Migration from Africa Less Than 95,000 Years Ago

Recent measurements of the rate at which children show DNA changes not seen in their parents -- the "mutation rate" -- have challenged views about major dates in human evolution.

In particular these measurements have made geneticists think again about key dates in human evolution, like when modern non-Africans split from modern Africans. The recent measurements push back the best estimates of these dates by up to a factor of two. Now, however an international team led by researchers at the University of Tübingen and the Max Planck Institute for Evolutionary Anthropology in Leipzig, present results that point again to the more recent dates. The new study is published in Current Biology.

The team, led by Johannes Krause from Tübingen University, was able to reconstruct more than ten mitochondrial genomes (mtDNAs) from modern humans from Eurasia that span 40,000 years of prehistory. The samples include some of the oldest modern human fossils from Europe such as the triple burial from Dolni Vestonice in the Czech Republic, as well as the oldest modern human skeletons found in Germany from the site of Oberkassel close to Bonn.

The researchers show that pre-ice age hunter-gatherers from Europe carry mtDNA that is related to that seen in post-ice age modern humans such as the Oberkassel fossils. This suggests that there was population continuity throughout the last major glaciation event in Europe around 20,000 years ago. Two of the Dolni Vestonice hunter-gatherers also carry identical mtDNAs, suggesting a close maternal relationship among these individuals who were buried together.

The researchers also used the radiocarbon age of the fossils to estimate human mutation rates over tens of thousands of year back in time. This was done by calculating the number of mutations in modern groups that are absent in the ancient groups, since they had not yet existed in the ancient population. The mutation rate was estimated by counting the number of mutations accumulated along descendent lineages since the radiocarbon dated fossils.

Using those novel mutation rates -- capitalizing on information from ancient DNA -- the authors cal-culate the last common ancestor for human mitochondrial lineages to around 160,000 years ago. In other words, all present-day humans have as one of their ancestors a single woman who lived around that time.

The authors also estimate the time since the most recent common ancestor of Africans and non-Africans to between 62,000-95,000 years ago, providing a maximum date for the mass migration of modern humans out of Africa. Those results are in agreement with previous mitochondrial dates based on archaeological and anthropological work but are at the extreme low end of the dates sug-gested from de-novo studies that suggest a split of non-Africans from Africans about thirty thousand years earlier.

 

"The results from modern family studies and our ancient human DNA studies are in conflict" says Krause. "One possibility is that mutations were missed in the modern family studies, which could lead to underestimated mutation rates." The authors argue that nuclear genomes from ancient modern humans may help to explain the discrepancies.

Source: Science Daily

M.Wassouf