Tag Archives: chemical

ALMA has observed stars like the Sun at a very early stage in their formation and found traces of methyl isocyanate — a chemical building block of life. This is the first ever detection of this prebiotic molecule towards a solar-type protostar, the sort from which our Solar System evolved. The discovery could help astronomers understand how life arose on Earth.

This image shows the spectacular region of star formation where methyl isocyanate was found. The insert shows the molecular structure of this chemical.

Credit:
ESO/Digitized Sky Survey 2/L. Calçada

ALMA Finds Ingredient of Life Around Infant Sun-like Stars

ALMA has observed stars like the Sun at a very early stage in their formation and found traces of methyl isocyanate — a chemical building block of life. This is the first ever detection of this prebiotic molecule towards solar-type protostars, the sort from which our Solar System evolved. The discovery could help astronomers understand how life arose on Earth.

Two teams of astronomers have harnessed the power of the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to detect the prebiotic complex organic molecule methyl isocyanate [1] in the multiple star system IRAS 16293-2422. One team was co-led by Rafael Martín-Doménech at the Centro de Astrobiología in Madrid, Spain, and Víctor M. Rivilla, at the INAF-Osservatorio Astrofisico di Arcetri in Florence, Italy; and the other by Niels Ligterink at the Leiden Observatory in the Netherlands and Audrey Coutens at University College London, United Kingdom.

ALMA has observed stars like the Sun at a very early stage in their formation and found traces of methyl isocyanate — a chemical building block of life. This is the first ever detection of this prebiotic molecule towards a solar-type protostar, the sort from which our Solar System evolved. The discovery could help astronomers understand how life arose on Earth. This image shows the spectacular region of star formation where methyl isocyanate was found. The insert shows the molecular structure of this chemical. Credit: ESO/Digitized Sky Survey 2/L. Calçada
ALMA has observed stars like the Sun at a very early stage in their formation and found traces of methyl isocyanate — a chemical building block of life. This is the first ever detection of this prebiotic molecule towards a solar-type protostar, the sort from which our Solar System evolved. The discovery could help astronomers understand how life arose on Earth.
This image shows the spectacular region of star formation where methyl isocyanate was found. The insert shows the molecular structure of this chemical.
Credit:
ESO/Digitized Sky Survey 2/L. Calçada

“This star system seems to keep on giving! Following the discovery of sugars, we’ve now found methyl isocyanate. This family of organic molecules is involved in the synthesis of peptides and amino acids, which, in the form of proteins, are the biological basis for life as we know it,” explain Niels Ligterink and Audrey Coutens [2].

ALMA’s capabilities allowed both teams to observe the molecule at several different and characteristic wavelengths across the radio spectrum [3]. They found the unique chemical fingerprints located in the warm, dense inner regions of the cocoon of dust and gas surrounding young stars in their earliest stages of evolution. Each team identified and isolated the signatures of the complex organic molecule methyl isocyanate [4]. They then followed this up with computer chemical modelling and laboratory experiments to refine our understanding of the molecule’s origin [5].

IRAS 16293-2422 is a multiple system of very young stars, around 400 light-years away in a large star-forming region called Rho Ophiuchi in the constellation of Ophiuchus (The Serpent Bearer). The new results from ALMA show that methyl isocyanate gas surrounds each of these young stars.

Earth and the other planets in our Solar System formed from the material left over after the formation of the Sun. Studying solar-type protostars can therefore open a window to the past for astronomers and allow them to observe conditions similar to those that led to the formation of our Solar System over 4.5 billion years ago.

Rafael Martín-Doménech and Víctor M. Rivilla, lead authors of one of the papers, comment: “We are particularly excited about the result because these protostars are very similar to the Sun at the beginning of its lifetime, with the sort of conditions that are well suited for Earth-sized planets to form. By finding prebiotic molecules in this study, we may now have another piece of the puzzle in understanding how life came about on our planet.”

Niels Ligterink is delighted with the supporting laboratory results: “Besides detecting molecules we also want to understand how they are formed. Our laboratory experiments show that methyl isocyanate can indeed be produced on icy particles under very cold conditions that are similar to those in interstellar space This implies that this molecule — and thus the basis for peptide bonds — is indeed likely to be present near most new young solar-type stars.”

Notes
[1] A complex organic molecule is defined in astrochemistry as consisting of six or more atoms, where at least one of the atoms is carbon. Methyl isocyanate contains carbon, hydrogen, nitrogen and oxygen atoms in the chemical configuration CH3NCO. This very toxic substance was the main cause of death following the tragic Bhopal industrial accident in 1984.

[2] The system was previously studied by ALMA in 2012 and found to contain molecules of the simple sugar glycolaldehyde, another ingredient for life.

[3] The team led by Rafael Martín-Doménech used new and archive data of the protostar taken across a large range of wavelengths across ALMA’s receiver Bands 3, 4 and 6. Niels Ligterink and his colleagues used data from the ALMA Protostellar Interferometric Line Survey (PILS), which aims to chart the chemical complexity of IRAS 16293-2422 by imaging the full wavelength range covered by ALMA’s Band 7 on very small scales, equivalent to the size of our Solar System.

[4] The teams carried out spectrographic analysis of the protostar’s light to determine the chemical constituents. The amount of methyl isocyanate they detected — the abundance — with respect to molecular hydrogen and other tracers is comparable to previous detections around two high-mass protostars (i.e. within the massive hot molecular cores of Orion KL and Sagittarius B2 North).

[5] Martín-Doménech’s team chemically modelled gas-grain formation of methyl isocyanate. The observed amount of the molecule could be explained by chemistry on the surface of dust grains in space, followed by chemical reactions in the gas phase. Moreover, Ligterink’s team demonstrated that the molecule can be formed at extremely cold interstellar temperatures, down to 15 Kelvin (–258 degrees Celsius), using cryogenic ultra-high-vacuum experiments in their laboratory in Leiden.

More information
This research was presented in two papers: “First Detection of Methyl Isocyanate (CH3NCO) in a solar-type Protostar” by R. Martín-Doménech et al. and “The ALMA-PILS survey: Detection of CH3NCO toward the low-mass protostar IRAS 16293-2422 and laboratory constraints on its formation”, by N. F. W. Ligterink et al.. Both papers will appear in the same issue of the Monthly Notices of the Royal Astronomical Society.

One team is composed of: R. Martín-Doménech (Centro de Astrobiología, Spain), V. M. Rivilla (INAF-Osservatorio Astrofisico di Arcetri, Italy), I. Jiménez-Serra (Queen Mary University of London, UK), D. Quénard (Queen Mary University of London, UK), L. Testi (INAF-Osservatorio Astrofisico di Arcetri, Italy; ESO, Garching, Germany; Excellence Cluster “Universe”, Germany) and J. Martín-Pintado (Centro de Astrobiología, Spain).

The other team is composed of: N. F. W. Ligterink (Sackler Laboratory for Astrophysics, Leiden Observatory, the Netherlands), A. Coutens (University College London, UK), V. Kofman (Sackler Laboratory for Astrophysics, The Netherlands), H. S. P. Müller (Universität zu Köln, Germany), R. T. Garrod (University of Virginia, USA), H. Calcutt (Niels Bohr Institute & Natural History Museum, Denmark), S. F. Wampfler (Center for Space and Habitability, Switzerland), J. K. Jørgensen (Niels Bohr Institute & Natural History Museum, Denmark), H. Linnartz (Sackler Laboratory for Astrophysics, The Netherlands) and E. F. van Dishoeck (Leiden Observatory, The Netherlands; Max-Planck-Institut für Extraterrestrische Physik, Germany).

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.

Source: ESO

The harlequin filefish can disguise its smell. Image: Tane Sinclair-Taylor

You are what you eat – if you’re a coral reef fish

In a world first study researchers have found a coral-eating fish that disguises its smell to hide from predators.

“For many animals vision is less important than their sense of smell,” says study lead author Dr Rohan Brooker from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University.

“Because predators often rely on odors to find their prey, even visually camouflaged animals may stick out like a sore thumb if they smell strongly of ‘food’.” Dr Brooker says.

The research, published in the journal Proceedings of the Royal Society B, found that the harlequin filefish changed its smell to match the coral it ate.

“By feeding on corals, the harlequin filefish ends up smelling enough like its food that predators have a hard time distinguishing it from the surrounding coral habitat,” Dr Brooker says.

The harlequin filefish can disguise its smell. Image: Tane Sinclair-Taylor
The harlequin filefish can disguise its smell. Image: Tane Sinclair-Taylor

Study co-author, Professor Philip Munday from the Coral CoE says the ability to chemically camouflage itself is a great advantage for the fish.

“The harlequin filefish shelters among the branches of coral colonies at night, where not only does it look like a coral branch, it also smells like one, enabling it to remain undetected by nocturnal predators.”

Professor Doug Chivers from the University of Saskatchewan, who is also a co-author, agrees.

“A finely-tuned combination of visual and chemical camouflage may be an effective anti-predator strategy that helps the fish to avoid being eaten,” Professor Chivers says.
Not only does the filefish confuse its predators, it matches the odour of the coral so closely that small crabs, which lived on coral branches, couldn’t distinguish it from coral.

Professor Munday says it’s a remarkable example of how closely animals can be adapted to their habitats.

“However, the filefishes’ cover is blown if it shelters in a different species of coral than the one it has been eating. Then, the predators can distinguish it presence and track it down,” Professor Munday says.

The ability to chemically ‘blend in’ occurs in some plant-eating invertebrates, but this is the first time this type of camouflage has been found in higher order animals, such as fish.

“This is very exciting because it opens the possibility of a wide range of different animals also using similar mechanisms, right under our noses,” Dr Brooker says.

Paper

You are what you eat: diet-induced chemical crypsis in a coral-feeding fish by Rohan Brooker, Philip Munday, Doug Chivers and Geoffrey Jones is published in the journal Proceedings of the Royal Society B.

Source : ARC Centre of Excellence Coral Reef Studies

Microscopic “walkers” find their way across cell surfaces

Technology could provide a way to deliver probes or drugs to cell structures without outside guidance.

By David Chandler


 

CAMBRIDGE, Mass–Nature has developed a wide variety of methods for guiding particular cells, enzymes, and molecules to specific structures inside the body: White blood cells can find their way to the site of an infection, while scar-forming cells migrate to the site of a wound. But finding ways of guiding artificial materials within the body has proven more difficult.

Now a team of researchers at MIT led by Alfredo Alexander-Katz, the Walter Henry Gale Associate Professor of Materials Science and Engineering, has demonstrated a new target-finding mechanism. The new system allows microscopic devices to autonomously find their way to areas of a cell surface, for example, just by detecting an increase in surface friction in places where more cell receptors are concentrated.

The finding is described this week in a paper in the journal Physical Review Letters, written by Alexander-Katz, graduate student Joshua Steimel, and postdoc Juan Aragones.

“The idea was to find out if we could create a synthetic, active system that could sense gradients in biological receptors,” Alexander-Katz explains. “Currently, we don’t know of anything that can do that.”

Cells have a way of locating areas that bear a specific kind of chemical signature — a process called chemotaxis. That’s the method used by white blood cells, for example, to locate regions where pathogens are attacking body cells.

“Our system is very simple,” Alexander-Katz says — similar to the way in which bacteria locate nutrients they need. The system, without guidance, samples areas on a surface and migrates toward those where friction is greater — which also correspond to areas where receptors are concentrated.

The system uses a pair of linked particles with magnetic properties. In the presence of a magnetic field, the paired particles begin to tumble across a surface, with first one particle and then the other making contact — in effect, “walking” across the surface.

So far, the work has been carried out on a model cell surface, on a functionalized microscope slide, but the effect should work similarly with living cells, Alexander-Katz says. The team’s goal now is to demonstrate the ability of the microscopic walkers to find their way toward concentrations of receptors in actual living tissue.

The method could potentially have a variety of applications, Alexander-Katz says. For example, it could be developed as a method of locating tumor cells within the body by identifying their surface texture, perhaps in combination with other characteristics.

Such magnetic microwalkers, he adds, could be unleashed to locate areas of interest on various kinds of surfaces, based solely on differences in friction. The particles naturally migrate toward high-friction regions, where they could then be induced to interact with a surface by active molecules attached to them.

“It’s a very versatile system,” Alexander-Katz says, that can be functionalized by attaching other kinds of receptors or binding agents to affect or monitor the target area in different ways.

The next step is to test the approach in more complex settings. The initial work was done with flat surfaces; the team now aims to conduct studies in complex 3-D settings to make sure the process works effectively in situations that more closely resemble a real cellular environment.

The research was supported by the U.S. Department of Energy, the MIT Energy Initiative, and the Chang family.

Engineering new bone growth

Coated tissue scaffolds help the body grow new bone to repair injuries or congenital defects.

By Anne Trafton


 

CAMBRIDGE, MA — MIT chemical engineers have devised a new implantable tissue scaffold coated with bone growth factors that are released slowly over a few weeks. When applied to bone injuries or defects, this coated scaffold induces the body to rapidly form new bone that looks and behaves just like the original tissue.

This type of coated scaffold could offer a dramatic improvement over the current standard for treating bone injuries, which involves transplanting bone from another part of the patient’s body — a painful process that does not always supply enough bone. Patients with severe bone injuries, such as soldiers wounded in battle; people who suffer from congenital bone defects, such as craniomaxillofacial disorders; and patients in need of bone augmentation prior to insertion of dental implants could benefit from the new tissue scaffold, the researchers say.

“It’s been a truly challenging medical problem, and we have tried to provide one way to address that problem,” says Nisarg Shah, a recent PhD recipient and lead author of the paper, which appears in the Proceedings of the National Academy of Sciences this week.

Paula Hammond, the David H. Koch Professor in Engineering and a member of MIT’s Koch Institute for Integrative Cancer Research and Department of Chemical Engineering, is the paper’s senior author. Other authors are postdocs M. Nasim Hyder and Mohiuddin Quadir, graduate student Noémie-Manuelle Dorval Courchesne, Howard Seeherman of Restituo, Myron Nevins of the Harvard School of Dental Medicine, and Myron Spector of Brigham and Women’s Hospital.

Stimulating bone growth

Two of the most important bone growth factors are platelet-derived growth factor (PDGF) and bone morphogenetic protein 2 (BMP-2). As part of the natural wound-healing cascade, PDGF is one of the first factors released immediately following a bone injury, such as a fracture. After PDGF appears, other factors, including BMP-2, help to create the right environment for bone regeneration by recruiting cells that can produce bone and forming a supportive structure, including blood vessels.

Efforts to treat bone injury with these growth factors have been hindered by the inability to effectively deliver them in a controlled manner. When very large quantities of growth factors are delivered too quickly, they are rapidly cleared from the treatment site — so they have reduced impact on tissue repair, and can also induce unwanted side effects.

“You want the growth factor to be released very slowly and with nanogram or microgram quantities, not milligram quantities,” Hammond says. “You want to recruit these native adult stem cells we have in our bone marrow to go to the site of injury and then generate bone around the scaffold, and you want to generate a vascular system to go with it.”

This process takes time, so ideally the growth factors would be released slowly over several days or weeks. To achieve this, the MIT team created a very thin, porous scaffold sheet coated with layers of PDGF and BMP. Using a technique called layer-by-layer assembly, they first coated the sheet with about 40 layers of BMP-2; on top of that are another 40 layers of PDGF. This allowed PDGF to be released more quickly, along with a more sustained BMP-2 release, mimicking aspects of natural healing.

The scaffold sheet is about 0.1 millimeter thick; once the growth-factor coatings are applied, scaffolds can be cut from the sheet on demand, and in the appropriate size for implantation into a bone injury or defect.

Effective repair

The researchers tested the scaffold in rats with a skull defect large enough — 8 millimeters in diameter — that it could not heal on its own. After the scaffold was implanted, growth factors were released at different rates. PDGF, released during the first few days after implantation, helped initiate the wound-healing cascade and mobilize different precursor cells to the site of the wound. These cells are responsible for forming new tissue, including blood vessels, supportive vascular structures, and bone.

BMP, released more slowly, then induced some of these immature cells to become osteoblasts, which produce bone. When both growth factors were used together, these cells generated a layer of bone, as soon as two weeks after surgery, that was indistinguishable from natural bone in its appearance and mechanical properties, the researchers say.

“Using this combination allows us to not only have accelerated proliferation first, but also facilitates laying down some vascular tissue, which provides a route for both the stem cells and the precursor osteoblasts and other players to get in and do their jobs. You end up with a very uniform healed system,” Hammond says.

Another advantage of this approach is that the scaffold is biodegradable and breaks down inside the body within a few weeks. The scaffold material, a polymer called PLGA, is widely used in medical treatment and can be tuned to disintegrate at a specific rate so the researchers can design it to last only as long as needed.

Hammond’s team has filed a patent based on this work and now aims to begin testing the system in larger animals in hopes of eventually moving it into clinical trials.

This study was funded by the National Institutes of Health.

Source: MIT News Office

The largest interstellar dust track found in the Stardust aerogel collectors was this 35 micron-long hole produced by a 3 picogram speck of dust that was probably traveling so fast that it vaporized upon impact. The other two likely interstellar dust grains were traveling more slowly and remained in
Image Credit: UC Berkeley/Andrew Westphal.

Stardust Team Reports Discovery of First Potential Interstellar Space Particles

Seven rare, microscopic interstellar dust particles that date to the beginnings of the solar system are among the samples collected by scientists who have been studying the payload from NASA’s Stardust spacecraft since its return to Earth in 2006. If confirmed, these particles would be the first samples of contemporary interstellar dust.

A team of scientists has been combing through the spacecraft’s aerogel and aluminum foil dust collectors since Stardust returned in 2006.The seven particles probably came from outside our solar system, perhaps created in a supernova explosion millions of years ago and altered by exposure to the extreme space environment.

The largest interstellar dust track found in the Stardust aerogel collectors was this 35 micron-long hole produced by a 3 picogram mote that was probably traveling so fast that it vaporized upon impact. The other two likely interstellar dust grains were traveling more slowly and remained intact after a soft landing in the aerogel. Image Credit: Andrew Westphal, UC Berkeley
The largest interstellar dust track found in the Stardust aerogel collectors was this 35 micron-long hole produced by a 3 picogram mote that was probably traveling so fast that it vaporized upon impact. The other two likely interstellar dust grains were traveling more slowly and remained intact after a soft landing in the aerogel.
Image Credit: Andrew Westphal, UC Berkeley

The research report appears in the Aug. 15 issue of the journal Science. Twelve other papers about the particles will appear next week in the journal Meteoritics & Planetary Science.

“These are the most challenging objects we will ever have in the lab for study, and it is a triumph that we have made as much progress in their analysis as we have,” said Michael Zolensky, curator of the Stardust laboratory at NASA’s Johnson Space Center in Houston and coauthor of the Science paper.

Stardust was launched in 1999 and returned to Earth on Jan. 15, 2006, at the Utah Test and Training Range, 80 miles west of Salt Lake City. The Stardust Sample Return Canister was transported to a curatorial facility at Johnson where the Stardust collectors remain preserved and protected for scientific study.

Inside the canister, a tennis racket-like sample collector tray captured the particles in silica aerogel as the spacecraft flew within 149 miles of a comet in January 2004. An opposite side of the tray holds interstellar dust particles captured by the spacecraft during its seven-year, three-billion-mile journey.

Scientists caution that additional tests must be done before they can say definitively that these are pieces of debris from interstellar space. But if they are, the particles could help explain the origin and evolution of interstellar dust.

The particles are much more diverse in terms of chemical composition and structure than scientists expected. The smaller particles differ greatly from the larger ones and appear to have varying histories. Many of the larger particles have been described as having a fluffy structure, similar to a snowflake.

The largest interstellar dust track found in the Stardust aerogel collectors was this 35 micron-long hole produced by a 3 picogram speck of dust that was probably traveling so fast that it vaporized upon impact. The other two likely interstellar dust grains were traveling more slowly and remained in Image Credit: UC Berkeley/Andrew Westphal.
The largest interstellar dust track found in the Stardust aerogel collectors was this 35 micron-long hole produced by a 3 picogram speck of dust that was probably traveling so fast that it vaporized upon impact. The other two likely interstellar dust grains were traveling more slowly and remained in
Image Credit: UC Berkeley/Andrew Westphal.

Two particles, each only about two microns (thousandths of a millimeter) in diameter, were isolated after their tracks were discovered by a group of citizen scientists. These volunteers, who call themselves “Dusters,” scanned more than a million images as part of a University of California, Berkeley, citizen-science project, which proved critical to finding these needles in a haystack.

A third track, following the direction of the wind during flight, was left by a particle that apparently was moving so fast — more than 10 miles per second (15 kilometers per second) — that it vaporized. Volunteers identified tracks left by another 29 particles that were determined to have been kicked out of the spacecraft into the collectors.

Four of the particles reported in Science were found in aluminum foils between tiles on the collector tray. Although the foils were not originally planned as dust collection surfaces, an international team led by physicist Rhonda Stroud of the Naval Research Laboratory searched the foils and identified four pits lined with material composed of elements that fit the profile of interstellar dust particles.

Three of these four particles, just a few tenths of a micron across, contained sulfur compounds, which some astronomers have argued do not occur in interstellar dust. A preliminary examination team plans to continue analysis of the remaining 95 percent of the foils to possibly find enough particles to understand the variety and origins of interstellar dust.

Supernovas, red giants and other evolved stars produce interstellar dust and generate heavy elements like carbon, nitrogen and oxygen necessary for life. Two particles, dubbed Orion and Hylabrook, will undergo further tests to determine their oxygen isotope quantities, which could provide even stronger evidence for their extrasolar origin.

Scientists at Johnson have scanned half the panels at various depths and turned these scans into movies, which were then posted online, where the Dusters could access the footage to search for particle tracks.

Once several Dusters tag a likely track, Andrew Westphal, lead author of the Science article, and his team verify the identifications. In the one million frames scanned so far, each a half-millimeter square, Dusters have found 69 tracks, while Westphal has found two. Thirty-one of these were extracted along with surrounding aerogel by scientists at Johnson and shipped to UC Berkeley to be analyzed.

NASA’s Jet Propulsion Laboratory, Pasadena, California, manages the Stardust mission for NASA’s Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, developed and operated the spacecraft.