New Worlds: Ocean-floor stardust shows gold and uranium rare in stars

Researchers analyzed core samples collected from the Pacific Ocean floor.

By JUDY SIEGEL-ITZKOVICH
Starry Sky (illustrative). (photo credit: REUTERS)
Starry Sky (illustrative).
(photo credit: REUTERS)
Researchers combing the ocean depths have made a surprising discovery about the frequency with which stars beyond our solar system produce certain rare heavy elements such as gold and uranium. Stellar explosions such as supernovae or star collisions emit extremely bright light and vast amounts of energy and heavy matter. Half of the heavy elements in nature, including gold and uranium, are created during such events, yet their frequency and their very sites in the galaxy remain a mystery.
By analyzing samples from the deep-sea floor that accumulated over millions of years, an international team of researchers that included an Israeli concluded that the frequency of such events is much lower than expected. The findings were published recently in the prestigious journal Nature Communications.
The researchers analyzed core samples collected from the Pacific Ocean floor at about 4,500 meters down. They measured Pu-244, a rare isotope of plutonium that accumulated in the deep sea from the deposition of interstellar particles.
According to study co-author Prof. Michael Paul at the Hebrew University of Jerusalem’s Racah Institute of Physics, “Our analysis of galactic debris that fell to Earth and settled in our oceans shows about 100 times less plutonium than we originally expected.”
According to Paul, “The stellar dust that collects in our oceans provides new information about the far reaches of space as well as our own planet.
Our research challenges current theories about supernovae and compounds the mystery surrounding how our solar system received its share of heavy elements. However it could be consistent with a particular astrophysical scenario, namely collisions or mergers of two neutron stars in the Milky Way galaxy.”
POSTDOC FELLOWSHIPS AT CAMBRIDGE
A benefactor of the University of Cambridge, Leonard Blavatnik, has made a multimillion-pound pledge to provide funding for Israeli scientists of outstanding ability to study on campus. As a leading university, Cambridge said it seeks to bring together the most brilliant minds to freely interact, learn and discover. “Its goal is to encourage and support the best people from around the world to work and study there,” the university said. “The new Blavatnik Family Foundation fellowships offer an important addition in support of this aim.”
The fellowship program, which will run for an initial period of five years, will be administered by the British Council in Israel, “which actively promotes academic and scientific exchange between Israel and the UK and is warmly supportive of the initiative.”
Fellows will receive an annual stipend of £30,000, and fellowships will be tenable for up to two years. It is planned that there will be at least three Fellows appointed each year, although it is anticipated that this number may increase in future years.
The first three fellows will research in the areas of engineering, genetics and physics. Potential fellows are encouraged to apply to the program by the British Council.
Successful applicants are selected by a committee of senior academics.
Cambridge vice chancellor Prof. Leszek Borysiewicz said: “We are committed to enabling the very best people from around the world to come to Cambridge, to drive forward our pioneering research and address new questions.”
Blavatnik, speaking on behalf of the foundation, added: “I am very pleased to strengthen the foundation’s existing links to Cambridge with this important initiative, which will serve the mutual interests of the university, the Israeli scientific community and those selected to be Blavatnik fellows.”
UK ambassador to Israel Matthew Gould said, “The Blavatnik Scholarships will hugely benefit both Britain and Israel and the friendship between them. Britain will have some of the leading young scientists in the world coming to do their research in Cambridge. Israeli scientists will get to work in one of the world’s top universities, and the scheme will strengthen the web of cooperation, friendship and respect between the two scientific communities.”
MOLECULAR BIOLOGY ‘AXIOM’ OVERTURNED
Even though modern biotechnology enables researchers to determine the entire DNA sequence for each individual patient, the major part of such information is currently unusable because the functional significance of over 95 percent of the DNA sequence is not understood. One of the most striking features of genomic DNA is that it contains numerous repetitive sequence patterns of unknown function. But Ben-Gurion University of the Negev researchers and their colleagues from Duke University in North Carolina have identified a possible function of such repetitive DNA patterns and discovered that these enhance the binding of regulatory proteins to DNA.
Genetic information is encoded into a long DNA molecule, containing billions of elementary building blocks called nucleotide bases. There are four types of such nucleotide bases – abbreviated A, T, C and G – and a genomic DNA molecule represents a long double-stranded chain composed of these nucleotides. Changes in the sequence of the DNA, called mutations, are responsible for numerous genetic disorders. Understanding the molecular mechanisms of how regulatory proteins, called transcription factors, recognize their specific binding sites encoded into genomic DNA represents one of the central, long-standing problems of molecular biology. Until now, it has reasonably been assumed that specific base-pair recognition is the only mechanism controlling the specificity of transcription factor-DNA binding.


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