|
|
'Bubblegram'
Imaging: Novel Approach to View Inner Workings of Viruses
Image of virus
and blow-up of inner virus structure. In the background, cryo-electron
micrographs of purified viruses with their inner structure bubbling from
radiation damage. Overlaid, (left) 3D computer reconstruction of a virus's
outer shell and tail in gray, with the inner structure in magenta; (right)
blow-up of the inner viral structure in magenta. (Credit: Image courtesy of
NIH/National Institute of Arthritis and Musculoskeletal and Skin Diseases)
Since the discovery of the microscope, scientists have tried to visualize
smaller and smaller structures to provide insights into the inner workings
of human cells, bacteria and viruses. Now, researchers at the National
Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), part
of the National Institutes of Health, have developed a new way to see
structures within viruses that were not clearly seen before.
Cryo-electron microscopy (cryo-EM) is a technique that allows scientists to
image very small particles, like structures on the surface of viruses. This
method has been useful in helping researchers understand how vaccines work.
But, despite the success of cryo-EM, scientists have been unable to clearly
visualize structures inside of viruses, because radiation is used to image
them. "With lower doses of radiation, it is not possible to see inside the
organism," said lead author Dr. Alasdair Steven of the NIAMS Laboratory of
Structural Biology Research. "However, higher doses of radiation damage the
virus, destroying the very structures that we would like to view."
Working in collaboration with the group of Dr. Lindsay Black at the
University of Maryland Medical School, Baltimore, Steven and his team were
able to turn the problem of radiation damage into an asset. Viruses, one of
the simplest life forms, are made up of nucleic acids (DNA or RNA) and the
proteins encoded by the nucleic acid instruction manual. The researchers
realized that proteins inside the virus are more sensitive to damage than
DNA.
"We first used low doses of radiation and recorded images in which the inner
structure of the virus was invisible," said Steven. "Next, we used high
doses of radiation, and found that the inner structure could be seen as a
cylinder of bubbles." While the inner structure was damaged, the team was
able to superimpose the images, using three-dimensional computer
reconstruction. As a result, they were able to clearly visualize the viral
structure. The investigators call this technique bubblegram imaging.
Moving forward, the team members anticipate many uses of bubblegram imaging.
Ideally, this technique will allow a better understanding of the inner
workings of viruses, providing more opportunities for developing novel
therapies. Beyond studying viral structure, cryo-EM could be used to
visualize interactions of proteins with DNA in human cells. One exciting
prospect lies in using this approach to visualize differences in cancer vs.
non-cancer cells. "This new cryo-EM procedure renders previously invisible
proteins visible and, thus, will provide new understanding of cell biology,"
said Steven.
Story Source:
The above story is reprinted from materials provided by NIH/National
Institute of Arthritis and Musculoskeletal and Skin Diseases.
Journal Reference:
W. Wu, J. A. Thomas, N. Cheng, L. W. Black, A. C. Steven. Bubblegrams Reveal
the Inner Body of Bacteriophage KZ. Science, 2012; 335 (6065): 182 DOI:
10.1126/science.1214120
Toward Twister Forecasting: Scientists Make Progress in Assessing Tornado
Seasons
Approaching
tornado. The small size and complexity of tornadoes makes forecasting
difficult. (Credit: © victor zastol'skiy / Fotolia)
Meteorologists can see a busy hurricane season brewing months ahead, but
until now there has been no such crystal ball for tornadoes, which are much
smaller and more volatile. This information gap took on new urgency after
tornadoes in 2011 killed more than 550 people, more than in the previous 10
years combined, including a devastating outbreak in April that racked up $5
billion in insured losses. Now, a new study of short-term climate trends
offers the first framework for predicting tornado activity up to a month out
with current technology, and possibly further out as climate models improve,
giving communities a chance to plan.
The study may also eventually open a window on the question of whether
tornadoes are growing more frequent due to long-term climate warming.
"Understanding how climate shapes tornado activity makes forecasts and
projections possible and allows us to look into the past and understand what
happened," said lead author Michael Tippett, a climate scientist at Columbia
University's International Research Institute for Climate and Society (IRI).
Packing winds of up to 300 miles per hour, tornadoes descend when warm,
moist air collides with cold, dry air, creating a vortex as the two masses
move around each other. The U.S. Midwest is the twister capital of the
world, where cold air blowing east from the Rockies habitually hits tropical
air moving north from the Gulf of Mexico. Tornadoes appear to be growing
more frequent as climate warms, but it is uncertain whether there is a
connection; they are small and hard to count, and recently improved
reporting may also explain the increase.
Lack of an accurate long-term tornado record makes it hard to know the
truth, and has also hampered scientists' ability to relate tornadoes to
cyclical weather patterns that could aid in forecasting. While individual
hurricanes can be spotted days in advance, tornadoes appear with much less
warning. A tornado watch typically gives only a few hours' notice that
dangerous conditions are brewing, while warning of an actual tornado bearing
down may give people just a few minutes to get out of the way.
Tippett, a seasonal forecasting expert, had already built statistical models
to understand how climate change might affect hurricanes by adding more heat
and moisture to the air. But applying the same methods to something as tiny
and complicated as a twister is trickier, said study coauthor Adam Sobel, an
atmospheric scientist with joint appointments at Columbia's Lamont-Doherty
Earth Observatory and School of Engineering and Applied Science. "A tornado
is not a lot bigger than the house it has just destroyed," he said. "It's a
small thing and short-lived."
Combing through 30 years of data, Tippett and his colleagues began looking
for patterns linking climate and tornadoes. By comparing average atmospheric
conditions with average monthly tornado counts in regions across the United
States, they identified two parameters that seemed closely associated with
monthly tornado activity: rain associated with strong updrafts; and helicity,
which measures the tendency of winds to spin those updrafts.
They then looked to see if they could "predict" the tornado activity of
individual months from 1979 to 2010 from a simple index based on each
month's average wind and rain parameters. The index correlated significantly
with the observed numbers of tornadoes in all months except September and
October. Moreover, the National Oceanic and Atmospheric Administration
(NOAA) system for making seasonal forecasts, known as the Climate Forecast
System (CFS), was able to use the index to forecast monthly tornado activity
with some success up to a month in advance. This success, especially notable
in June, is the first evidence for the predictability of monthly tornado
activity.
Harold Brooks, a NOAA tornado expert not involved in the study said the
forecast technique worked where others have failed because the CFS produced
higher resolution results. "The real breakthrough is that CFS is skillful
enough at the right scale," he said.With greater lead time, communities and
relief agencies could prepare, he said. "It's not like the hurricane problem
where we can tell people to evacuate. But if I'm a state emergency manager I
might be really interested in knowing at the end of March that by the end of
April we could have a big problem. You could be better prepared with
generators and supplies."
Tippett said the next steps are to improve the index's reliability in the
fall; to better understand why the forecasts work; and to apply the index to
projections of future climate. "Before you can use an index to diagnose
future climate, you have to be confident that it explains the observed
variability," he said.
Suzana Camargo, a climate and weather researcher at Lamont-Doherty Earth
Observatory, also coauthored the study, which appears this week in the
journal Geophysical Research Letters.
Story Source:
The above story is reprinted from materials provided by The Earth Institute
at Columbia University.
Journal Reference:
Michael K. Tippett, Adam H. Sobel, Suzana J. Camargo. Association of U.S.
tornado occurrence with monthly environmental parameters. Geophysical
Research Letters, 2012; 39 (2) DOI: 10.1029/2011GL050368
Almost Perfect: Researcher Nears Creation of Superlens
In this
illustration of Durdu Guney's theoretical metamaterial, the colors show
magnetic fields generated by plasmons. The black arrows show the direction
of electrical current in metallic layers, and the numbers indicate current
loops that contribute to negative refraction. (Credit: Image courtesy of
Michigan Technological University)
A superlens would let you see a virus in a drop of blood and open the door
to better and cheaper electronics. It might, says Durdu Guney, make
ultra-high-resolution microscopes as commonplace as cameras in our cell
phones.
No one has yet made a superlens, also known as a perfect lens, though people
are trying. Optical lenses are limited by the nature of light, the so-called
diffraction limit, so even the best won't usually let us see objects smaller
than 200 nanometers across, about the size of the smallest bacterium.
Scanning electron microscopes can capture objects that are much smaller,
about a nanometer wide, but they are expensive, heavy, and, at the size of a
large desk, not very portable.
To build a superlens, you need metamaterials: artificial materials with
properties not seen in nature. Scientists are beginning to fabricate
metamaterials in their quest to make real seemingly magical phenomena like
invisibility cloaks, quantum levitation -- and superlenses.
Now Guney, an assistant professor of electrical and computer engineering at
Michigan Technological University, has taken a major step toward creating
superlens that could use visible light to see objects as small as 100
nanometers across.
The secret lies in plasmons, charge oscillations near the surface of thin
metal films that combine with special nanostructures. When excited by an
electromagnetic field, they gather light waves from an object and refract it
in a way not seen in nature called negative refraction. This lets the lens
overcomes the diffraction limit. And, in the case of Guney's model, it could
allow us to see objects smaller than 1/1,000th the width of a human hair.
Other researchers have also been able to sidestep the diffraction limit, but
not throughout the entire spectrum of visible light. Guney's model showed
how metamaterials might be "stretched" to refract light waves from the
infrared all the way past visible light and into the ultraviolet spectrum.
Making these superlenses would be relatively inexpensive, which is why they
might find their way into cell phones. But there would be other uses as
well, says Guney.
"It could also be applied to lithography," the microfabrication process used
in electronics manufacturing. "The lens determines the feature size you can
make, and by replacing an old lens with this superlens, you could make
smaller features at a lower cost. You could make devices as small as you
like."
Computer chips are made using UV lasers, which are expensive and difficult
to build. "With this superlens, you could use a red laser, like the pointers
everyone uses, and have simple, cheap machines, just by changing the lens."
What excites Guney the most, however, is that a cheap, accessible superlens
could open our collective eyes to worlds previously known only to a very
few.
"The public's access to high-powered microscopes is negligible," he says.
"With superlenses, everybody could be a scientist. People could put their
cells on Facebook. It might just inspire society's scientific soul."
Guney and graduate student Muhammad Aslam published an article on their
work, "Surface Plasmon Diven Scalable Low-Loss Negative-Index Metamaterial
in the visible spectrum," in Physical Review B, volume 84, issue 19.0
Story Source:
The above story is reprinted from materials provided by Michigan
Technological University. The original article was written by Marcia
Goodrich.
Journal Reference:
Muhammad Aslam, Durdu Ö. Güney. Surface plasmon driven scalable low-loss
negative-index metamaterial in the visible spectrum. Physical Review B,
2011; 84 (19) DOI: 10.1103/PhysRevB.84.195465
Harp Seals On Thin Ice After 32 Years of Warming
The breeding
regions of harp seals (Pagophilus groenlandicus) and patterns of the North
Atlantic Oscillation (NAO). Red dots illustrate the general breeding
locations of harp seals and the effects of both positive (+) and negative
(-) phases of the winter NAO on these regions are indicated. (Credit:
Johnston DW, Bowers MT, Friedlaender AS, Lavigne DM. The Effects of Climate
Change on Harp Seals (Pagophilus groenlandicus). PLoS ONE, 7(1): e29158 DOI:
10.1371/journal.pone.0029158)
Warming in the North Atlantic over the last 32 years has significantly
reduced winter sea ice cover in harp seal breeding grounds, resulting in
sharply higher death rates among seal pups in recent years, according to a
new Duke University-led study.
"The kind of mortality we're seeing in eastern Canada is dramatic. Entire
year-classes may be disappearing from the population in low ice years --
essentially all of the pups die," said David W. Johnston, research scientist
at the Duke University Marine Lab. "It calls into question the resilience of
the population."
The study, recently published in the peer-reviewed journal PLoS ONE, is the
first to show that seasonal sea ice cover in all four harp seal breeding
regions in the North Atlantic has declined by up to 6 percent a decade since
1979, when satellite records of ice conditions in the region began.
Harp seals rely on stable winter sea ice as safe places to give birth and
nurse their young until the pups can swim and hunt on their own. Female
seals typically seek out the thickest, oldest ice packs in sub-Arctic waters
each February and March, and have adapted to the spring melt by developing
unusually short, 12-day nursing periods.
"As a species, they're well suited to deal with natural short-term shifts in
climate, but our research suggests they may not be well adapted to absorb
the effects of short-term variability combined with longer-term climate
change and other human influences such as hunting and by-catch," Johnston
said.
To assess the cumulative impacts of these factors, the researchers analyzed
satellite images of winter ice from 1992 to 2010 in the Gulf of St. Lawrence
-- a major breeding region off Canada's east coast -- and compared them to
yearly reports of dead seal pup strandings in the region. They also compared
the stranding rates to recorded measurements of the relative strength of the
North Atlantic Oscillation (NAO), a climate phenomenon that controls the
intensity and track of westerly winds and storms and greatly affects winter
weather and sea ice formation in the region. These analyses revealed that
higher pup mortalities occurred in the Northwest Atlantic harp seal herd in
years with lighter ice cover and when the NAO was weaker.
Analysis of older data revealed that NAO-related changes in seasonal ice
cover may have contributed to major declines in seal populations on the east
coast of Canada from 1950 to 1972, and to a period of steady recovery from
1973 to 2000.
"This clearly shows that harp seal populations across the Atlantic fluctuate
pretty much in synch with NAO trends and associated winter ice conditions,"
Johnston said. "But there's a caveat. Regardless of NAO conditions, our
models show that sea ice cover in all harp seal breeding regions in the
North Atlantic have been declining by as much as 6 percent a decade over the
study period. The losses in bad years outweigh the gains in good years."
A key unanswered question, he added, is whether seals will be able to
respond to the long-term trend by moving to other, more stable ice habitats.
Recent reports that some harp seals are whelping in new breeding grounds off
East Greenland indicate some shifting may be taking place, but thousands
still return each year to traditional breeding grounds in the Gulf of St.
Lawrence or along the Front, off Newfoundland, regardless of ice conditions.
"There's only so much ice out there, and declines in the quantity and
quality of it across the region, coupled with the earlier arrival of spring
ice breakup, is literally leaving these populations on thin ice," Johnston
said. "It may take years of good ice and steady population gains to make up
for the heavy losses sustained during the recent string of bad ice years in
eastern Canada."
Co-authors of the study are doctoral student Matthew T. Bowers and research
scientist Ari S. Friedlaender, both of Duke, and David M. Lavigne, science
advisor at the International Fund for Animal Welfare, which funded the
study.
Story Source:
The above story is reprinted from materials provided by Duke University.
Journal Reference:
Johnston DW, Bowers MT, Friedlaender AS, Lavigne DM. The Effects of Climate
Change on Harp Seals (Pagophilus groenlandicus). PLoS ONE, 7(1): e29158 DOI:
10.1371/journal.pone.0029158
Umbilical Cord
Stem Cells Converted Into Brain Support Cells
James Hickman.
(Credit: Image courtesy of University of Central Florida)
For the first time ever, stem cells from umbilical cords have been converted
into other types of cells, which may eventually lead to new treatment
options for spinal cord injuries and multiple sclerosis, among other nervous
system diseases.
"This is the first time this has been done with non-embryonic stem cells,"
says James Hickman, a University of Central Florida bioengineer and leader
of the research group, whose accomplishment is described in the Jan. 18
issue of the journal ACS Chemical Neuroscience.
"We're very excited about where this could lead because it overcomes many of
the obstacles present with embryonic stem cells."
Stem cells from umbilical cords do not pose an ethical dilemma because the
cells come from a source that would otherwise be discarded. Another major
benefit is that umbilical cells generally have not been found to cause
immune reactions, which would simplify their potential use in medical
treatments.
The pharmaceutical company Geron, based in Menlo Park, Calif., developed a
treatment for spinal cord repair based on embryonic stem cells, but it took
the company 18 months to get approval from the FDA for human trials due in
large part to the ethical and public concerns tied to human embryonic stem
cell research. This and other problems recently led to the company shutting
down its embryonic stem cell division, highlighting the need for other
alternatives.
Sensitive Cells
The main challenge in working with stem cells is figuring out the chemical
or other triggers that will convince them to convert into a desired cell
type. When the new paper's lead author, Hedvika Davis, a postdoctoral
researcher in Hickman's lab, set out to transform umbilical stem cells into
oligodendrocytes -- critical structural cells that insulate nerves in the
brain and spinal cord -- she looked for clues from past research.
Davis learned that other research groups had found components on
oligodendrocytes that bind with the hormone norephinephrine, suggesting the
cells normally interact with this chemical and that it might be one of the
factors that stimulates their production. So, she decided this would be a
good starting point.
In early tests, she found that norepinephrine, along with other stem cell
growth promoters, caused the umbilical stem cells to convert, or
differentiate, into oligodendrocytes. However, that conversion only went so
far. The cells grew but then stopped short of reaching a level similar to
what's found in the human nervous system.
Davis decided that, in addition to chemistry, the physical environment might
be critical.
To more closely approximate the physical restrictions cells face in the
body, Davis set up a more confined, three-dimensional environment, growing
cells on top of a microscope slide, but with a glass slide above them. Only
after making this change, and while still providing the norephinphrine and
other chemicals, would the cells fully mature into oligodendrocytes.
"We realized that the stem cells are very sensitive to environmental
conditions," Davis said.
Medical Potential
This growth of oligodendrocytes, while crucial, is only a first step to
potential medical treatments. There are two main options the group hopes to
pursue through further research. The first is that the cells could be
injected into the body at the point of a spinal cord injury to promote
repair.
Another intriguing possibility for the Hickman team's work relates to
multiple sclerosis and similar conditions. "Multiple sclerosis is one of the
holy grails for this kind of research," said Hickman, whose group is
collaborating with Stephen Lambert at UCF's medical school, another of the
paper's authors.
Oligodendrocytes produce myelin, which insulates nerve cells, making it
possible for them to conduct the electrical signals that guide movement and
other functions. Loss of myelin leads to multiple sclerosis and other
related conditions such as diabetic neuropathy.
The injection of new, healthy oligodendrocytes might improve the condition
of patients suffering from such diseases. The teams are also hoping to
develop the techniques needed to grow oligodendrocytes in the lab to use as
a model system both for better understanding the loss and restoration of
myelin and for testing potential new treatments.
"We want to do both," Hickman said. "We want to use a model system to
understand what's going on and also to look for possible therapies to repair
some of the damage, and we think there is great potential in both
directions."
Besides Hickman and Davis, the other authors on the paper were Xiufang Guo,
Stephen Lambert, and Maria Stancescu, all from the University of Central
Florida.
Story Source:
The above story is reprinted from materials provided by University of
Central Florida.
Journal Reference:
Hedvika Davis, Xiufang Guo, Stephen Lambert, Maria Stancescu, James J.
Hickman. Small Molecule Induction of Human Umbilical Stem Cells into Myelin
Basic Protein Positive Oligodendrocytes in a Defined Three-Dimensional
Environment. ACS Chemical Neuroscience, 2011; 111129100355003 DOI:
10.1021/cn200082q
Unusual 'Tulip' Creature Discovered: Lived in the Ocean More Than 500
Million Years Ago
Cluster of four
specimens of Siphusauctum gregarium. Scale = 10 mm. (Credit: © Royal Ontario
Museum)
A bizarre creature that lived in the ocean more than 500-million years ago
has emerged from the famous Middle Cambrian Burgess Shale in the Canadian
Rockies.
Officially named Siphusauctum gregarium, fossils reveal a tulip-shaped
creature that is about the length of a dinner knife (approximately 20
centimetres) and has a unique filter feeding system.
Siphusauctum has a long stem, with a calyx -- a bulbous cup-like structure
-- near the top that encloses an unusual filter feeding system and a gut.
The animal is thought to have fed by filtering particles from water actively
pumped into its calyx through small holes. The stem ends with a small disc
which anchored the animal to the seafloor. Siphusauctum lived in large
clusters, as indicated by slabs containing over 65 individual specimens.
Lorna O'Brien, a PhD candidate in the Department of Ecology and Evolutionary
Biology at the University of Toronto and her supervisor, adjunct professor
Jean-Bernard Caron, curator of invertebrate palaeontology at the Royal
Ontario Museum, reported on the discovery Jan. 18 in the online science
journal PLoS ONE.
"Most interesting is that this feeding system appears to be unique among
animals. Recent advances have linked many bizarre Burgess Shale animals as
primitive members of many animal groups that are found today, but
Siphusauctum defies this trend. We do not know where it fits in relation to
other organisms," said lead author O'Brien.
"Our description is based on more than 1,100 fossil specimens from a new
Burgess Shale locality that has been nicknamed the Tulip Beds," she added.
Located in Yoho National Park, British Columbia, the Tulip Beds were first
discovered in 1983 by the Royal Ontario Museum. They are located high on
Mount Stephen, overlooking the town of Field. Like the rest of the Burgess
Shale, the beds represent rock layers with exceptional preservation of
mostly soft-bodied organisms.
The Burgess Shale, protected under the larger Rocky Mountain Parks UNESCO
World Heritage site and managed by Parks Canada, preserves fossil evidence
of some of the earliest complex animals that lived in the oceans of our
planet nearly 505 million years ago. The discovery of Siphusauctum expands
the range of animal diversity that existed during this time period.
The research was partially funded by UofT fellowships to O'Brien and a
Natural Sciences and Engineering Research Council of Canada Discovery Grant
awarded to Caron.
Story Source:
The above story is reprinted from materials provided by University of
Toronto. The original article was written by Kim Luke.
Journal Reference:
Lorna J. O'Brien, Jean-Bernard Caron. A New Stalked Filter-Feeder from the
Middle Cambrian Burgess Shale, British Columbia, Canada. PLoS ONE, 2012; 7
(1): e29233 DOI: 10.1371/journal.pone.0029233
How Protein in Teardrops Annihilates Harmful Bacteria: Novel Technology
Reveals Lysozymes Have Jaws
Rendering of lysozyme molecule. (Credit: Image courtesy of University of
California - Irvine)
A disease-fighting protein in our teardrops has been tethered to a tiny
transistor, enabling UC Irvine scientists to discover exactly how it
destroys dangerous bacteria. The research could prove critical to long-term
work aimed at diagnosing cancers and other illnesses in their very early
stages.
Ever since Nobel laureate Alexander Fleming found that human tears contain
antiseptic proteins called lysozymes about a century ago, scientists have
tried to solve the mystery of how they could relentlessly wipe out far
larger bacteria. It turns out that lysozymes have jaws that latch on and
chomp through rows of cell walls like someone hungrily devouring an ear of
corn, according to findings that will be published Jan. 20 in the journal
Science.
"Those jaws chew apart the walls of the bacteria that are trying to get into
your eyes and infect them," said molecular biologist and chemistry professor
Gregory Weiss, who co-led the project with associate professor of physics &
astronomy Philip Collins.
The researchers decoded the protein's behavior by building one of the
world's smallest transistors -- 25 times smaller than similar circuitry in
laptop computers or smartphones. Individual lysozymes were glued to the live
wire, and their eating activities were monitored.
"Our circuits are molecule-sized microphones," Collins said. "It's just like
a stethoscope listening to your heart, except we're listening to a single
molecule of protein."
It took years for the UCI scientists to assemble the transistor and attach
single-molecule teardrop proteins. The scientists hope the same novel
technology can be used to detect cancerous molecules. It could take a decade
to figure out but would be well worth it, said Weiss, who lost his father to
lung cancer.
"If we can detect single molecules associated with cancer, then that means
we'd be able to detect it very, very early," Weiss said. "That would be very
exciting, because we know that if we treat cancer early, it will be much
more successful, patients will be cured much faster, and costs will be much
less."
The project was sponsored by the National Cancer Institute and the National
Science Foundation. Co-authors of the Science paper are Yongki Choi, Issa
Moody, Patrick Sims, Steven Hunt, Brad Corso and Israel Perez.
Story Source:
The above story is reprinted from materials provided by University of
California - Irvine.
Journal Reference:
Y. Choi, I. S. Moody, P. C. Sims, S. R. Hunt, B. L. Corso, I. Perez, G. A.
Weiss, P. G. Collins. Single-Molecule Lysozyme Dynamics Monitored by an
Electronic Circuit. Science, 2012; 335 (6066): 319 DOI:
10.1126/science.1214824
Helix Nebula in New Colors
VISTA’s look at
the Helix Nebula: ESO's Visible and Infrared Survey Telescope for Astronomy
(VISTA) has captured this unusual view of the Helix Nebula (NGC 7293), a
planetary nebula located 700 light-years away. The coloured picture was
created from images taken through Y, J and K infrared filters. While
bringing to light a rich background of stars and galaxies, the telescope's
infrared vision also reveals strands of cold nebular gas that are mostly
obscured in visible images of the Helix. (Credit: ESO/VISTA/J. Emerson.
Acknowledgment: Cambridge Astronomical Survey Unit)
ESO's VISTA telescope, at the Paranal Observatory in Chile, has captured a
striking new image of the Helix Nebula. This picture, taken in infrared
light, reveals strands of cold nebular gas that are invisible in images
taken in visible light, as well as bringing to light a rich background of
stars and galaxies.
The Helix Nebula is one of the closest and most remarkable examples of a
planetary nebula*. It lies in the constellation of Aquarius (The Water
Bearer), about 700 light-years away from Earth. This strange object formed
when a star like the Sun was in the final stages of its life. Unable to hold
onto its outer layers, the star slowly shed shells of gas that became the
nebula. It is evolving to become a white dwarf star and appears as the tiny
blue dot seen at the centre of the image.
The nebula itself is a complex object composed of dust, ionised material as
well as molecular gas, arrayed in a beautiful and intricate flower-like
pattern and glowing in the fierce glare of ultraviolet light from the
central hot star.
The main ring of the Helix is about two light-years across, roughly half the
distance between the Sun and the nearest star. However, material from the
nebula spreads out from the star to at least four light-years. This is
particularly clear in this infrared view since red molecular gas can be seen
across much of the image.
While hard to see visually, the glow from the thinly spread gas is easily
captured by VISTA's special detectors, which are very sensitive to infrared
light. The 4.1-metre telescope is also able to detect an impressive array of
background stars and galaxies.
The powerful vision of ESO's VISTA telescope also reveals fine structure in
the nebula's rings. The infrared light picks out how the cooler, molecular
gas is organised. The material clumps into filaments that radiate out from
the centre and the whole view resembles a celestial firework display.
Even though they look tiny, these strands of molecular hydrogen, known as
cometary knots, are about the size of our Solar System. The molecules in
them are able to survive the high-energy radiation that emanates from the
dying star precisely because they clump into these knots, which in turn are
shielded by dust and molecular gas. It is currently unclear how the cometary
knots may have originated.
Please note that this text was modified on 18 January 2012 to correct some
minor errors.
*Planetary nebulae have nothing to do with planets. This confusing name
arose because many of them show small bright discs when observed visually
and resemble the outer planets in the Solar System, such as Uranus and
Neptune. The Helix Nebula, which also bears the catalogue number NGC 7293,
is unusual as it appears very large, but also very faint, when viewed
through a small telescope.
Story Source:
The above story is reprinted from materials provided by European Southern
Observatory (ESO).
Inventory Lists 19,232 Newly Discovered Species During Latest Count
Invertebrates
account for nearly 75 percent of the 19,232 species newly known to science
in 2009, the most recent calendar year of compilation, according to the 2011
State of Observed Species (SOS) report released Jan. 18, 2012, by the
International Institute for Species Exploration at Arizona State University.
(Credit: International Institute for Species Exploration/Arizona State
University)
More than half of the 19,232 species newly known to science in 2009, the
most recent calendar year of compilation, were insects -- 9,738 or 50.6
percent -- according to the 2011 State of Observed Species (SOS) report
released Jan. 18 by the International Institute for Species Exploration at
Arizona State University.
The second largest group in the 2009 numbers was vascular plants, totaling
2,184 or 11.3 percent. Of the 19,232 in the total count, seven were birds,
41 were mammals and 1,487 were arachnids -- spiders and mites.
And, according to this latest report, there was a 5.6 percent increase in
new living species discovered in 2009, compared to 2008.
The annual SOS report card on the status of human knowledge of Earth's
species summarizes what is known about global flora and fauna. The 19,232
species described as "new" or newly discovered during calendar year 2009
represent about twice as many species as were known in the lifetime of
Carolus Linnaeus, the Swedish botanist who initiated the modern system of
plant and animal names and classifications more than 250 years ago, said the
report's author, Quentin Wheeler, an ASU entomologist and founding director
of the species institute.
"The cumulative knowledge of species since 1758 when Linnaeus was alive is
nearly 2 million, but much remains to be done," Wheeler said. "A reasonable
guess is that 10 million additional plant and animal species await discovery
by scientists and amateur species explorers."
Additionally, recent macrogenomic surveys of DNA from terrestrial and marine
environments have revealed "enormous and previously unsuspected levels of
genetic diversity that corresponds in some not-yet-understood way to species
diversity," explained Wheeler.
"It has been speculated, for example, that marine microbial species alone
could number 20 million," he said.
With those staggering numbers as a backdrop, statistics, or "species bites,"
from the latest report note that:
Almost 24 percent of the new vascular plant species discovered in 2009 were
in the monocot order Asparagales, which includes orchids, hyacinths, irises,
daffodils, amaryllis, allium, aloe and, of course, asparagus.
Year to year, the largest order of newly discovered insects is the beetles,
and, 2009 was no exception. Overall, 3,485 new beetle species (Coleoptera)
were officially described including rove beetles (568), ground beetles
(421), long-horned beetles (369), leaf beetles (356) and scarabs (288).
"As the number of species increases, so too does our understanding of the
biosphere," said Wheeler, a professor in the School of Sustainability and a
Senior Sustainability Scientist in the Global Institute of Sustainability at
ASU. "It is through knowledge of the unique attributes of species that we
illuminate the origin and evolutionary history of life on our planet. As we
find out where species live and how they interact, we increase our ability
to understand the function of ecosystems and make effective, fact-based
decisions regarding conservation."
This is the fourth year for the annual State of Observed Species report
compiled by the International Institute for Species Exploration. In addition
to the 2011 report, the institute is also releasing a Retro SOS -- a decade
of species discovery in review -- 2000-2009. The Retro SOS notes that from
2000 through 2009, there were 176,311 newly discovered species.
"It is particularly instructive to understand the tempo and patterns of
discovery in recent years," said Wheeler, adding, "Given this data, it is
interesting to ponder underlying causes of trends."
The "obvious lesson" from compiling this data, according to Wheeler, is that
all nomenclatural acts, including descriptions of new species, must be
mandatorily registered going forward. "In the animal world it takes about
two years to mine the international literature for evidence of newly named
species. The current lack of registration requirements simply compounds the
problem of an already massive backlog," he said.
The report notes there are increasing calls for more aggressive and
visionary approaches to mapping the species of the biosphere. "The
adaptation of cyberinfrastructure to eliminate bottlenecks in the practice
of taxonomy has created an opportunity to vastly accelerate species
exploration," said Wheeler, who uses the SOS report and the annual naming of
the top 10 new species each May, as ways to draw attention to this mission.
The SOS report and the Retro SOS are filled with statistics and charts,
including a colorful word cloud. Sara Pennak, assistant director for
partnerships and public outreach at the institute, prepared the data
synthesis and analysis for the reports, which are available online at
http://species.asu.edu.
Partners in this effort include: Algae Base. MycoBank, International Journal
of Systematic and Evolutionary Microbiology, World Register of Marine
Species (WoRMS), Thomson Reuters Zoological Record, International Plant
Names Index, UniProt and Taxatoy.
Story Source:
The above story is reprinted from materials provided by Arizona State
University, via Newswise.
Most Distant Dwarf Galaxy Detected
The
gravitational lens B1938+666 as seen in the infrared when observed with the
10-meter Keck II telescope with Adaptive Optics on Mauna Kea, Hawaii. In the
center is a massive red galaxy 9.8 billion light-years from Earth that acts
like a cosmic magnifying glass, distorting the light from an even more
distant galaxy. The result is a spectacular Einstein ring image of the
background galaxy. (Credit: D. Lagattuta / W. M. Keck Observatory)
Scientists have long struggled to detect the dim dwarf galaxies that orbit
our own galaxy. So it came as a surprise on Jan. 18 when a team of
astronomers using Keck II telescope's adaptive optics has announced the
discovery of a dwarf galaxy halfway across the universe.
The new dwarf galaxy found by MIT's Dr. Simona Vegetti and colleagues is a
satellite of an elliptical galaxy almost 10 billion light-years away from
Earth. The team detected it by studying how the massive elliptical galaxy,
called JVAS B1938 + 666, serves as a gravitational lens for light from an
even more distant galaxy directly behind it. Their discovery was published
in the Jan. 18 online edition of the journal Nature.
Like all supermassive elliptical galaxies, JVAS B1938 + 666's gravity can
deflect light passing by it. Often the light from a background galaxy gets
deformed into an arc around the lens galaxy, and sometimes what's called an
Einstein ring. In this case, the ring is formed mainly by two lensed images
of the background galaxy. The size, shape and brightness of the Einstein
ring depends on the distribution of mass throughout the foreground lensing
galaxy.
Vegetti and her team obtained extra sharp near-infrared image of JVAS B1938
+ 666 by using the 10-meter Keck II telescope and its adaptive optics
system, which corrects for the blurring effects of Earth's atmosphere, and
provides stunningly sharp images. With these data, they neatly determined
the mass distribution of JVAS B1938 + 666 as well as the shape and
brightness of the background galaxy.
The researchers used a sophisticated numerical technique to derive a model
of the lens galaxy's mass, as well as to map any excess lens mass that could
not be accounted for by the galaxy. What they found was an excess mass near
the Einstein ring that they attributed to the presence of a satellite, or
"dwarf," galaxy. Vegetti's team also used a separate analytical model to
test the detected excess mass. They found that a satellite galaxy is indeed
required to explain the data.
"This satellite galaxy is exciting because it was detected in the
excess-mass map despite its low mass," commented Robert Schmidt of the
Center for Astronomy at Heidelberg University, in a related Nature article.
"A natural question to ask is whether the satellite galaxy can be observed
directly rather than by its gravitational effect on the shape of a
background object. With current instrumentation, the answer is no. The
object is simply too distant to be imaged directly. But the message here is
that it is possible to spot these elusive objects around distant lens
galaxies without knowing where to look for them."
Galaxies like our own are believed to form over billions of years through
the merging of many smaller galaxies. So it's expected that there should be
many smaller dwarf galaxies buzzing around the Milky Way. However, very few
of these tiny relic galaxies have been observed which has led astronomers to
conclude that many of them must have very few stars or possibly may be made
almost exclusively of dark matter.
Scientists theorize the existence of dark matter to explain observations
that suggest there is far more mass in the universe than can be seen.
However, because the particles that make up dark matter do not absorb or
emit light, they have so far proven impossible to detect and identify.
Computer modeling suggests that the Milky Way should have about 10,000
satellite dwarf galaxies, but only 30 have been observed.
"It could be that many of the satellite galaxies are made of dark matter,
making them elusive to detect, or there may be a problem with the way we
think galaxies form," says Vegetti.
In the new study, Vegetti worked with Prof. Leon Koopmans of the University
of Groningen, Netherlands; Dr. David Lagattuta and Prof. Christopher
Fassnacht of the University of California at Davis; Dr. Matthew Auger of the
University of California at Santa Barbara; and Dr. John McKean of the
Netherlands Institute for Radio Astronomy.
"The existence of this low-mass dark galaxy is just within the bounds we
expect if the Universe is composed of dark matter which has a low
temperature. However, further dark satellites will need to be found to
confirm this conclusion," says Vegetti.
Story Source:
The above story is reprinted from materials provided by W. M. Keck
Observatory.
Journal Reference:
S. Vegetti, D. J. Lagattuta, J. P. McKean, M. W. Auger, C. D. Fassnacht, L.
V. E. Koopmans. Gravitational detection of a low-mass dark satellite galaxy
at cosmological distance. Nature, 2012; 481 (7381): 341 DOI:
10.1038/nature10669
Source:
S.D.Tech
Courtesy:
Researcher |
|
Researcher