Why Some Plants Flower in Spring, Autumn and Some in Summer

A team of researchers from Warwick have isolated a gene responsible for regulating the expression of CONSTANS, an important inducer of flowering, in Arabidopsis.

'Being able to understand and ultimately control seasonal flowering will enable more predictable flowering, better scheduling and reduced wastage of crops', explained Dr Jackson.

Whilst the relationship between CONSTANS and flowering time in response to day length is well established, the mechanism controlling the expression of CONSTANS is still not fully understood.

The scientists present their work at the Society for Experimental Biology Annual Meeting in Prague.

Many plants control when they flower to coincide with particular seasons by responding to the length of the day, a process known as photoperiodism. A flowering mutant of Arabidopsis, which had an altered response to photoperiod, was used in the study led by Dr Stephen Jackson.

In the study funded by the BBSRC, the team identified the defective gene in the mutant plant that caused its abnormal flowering time.

They then cloned a working version of the gene, known as DAY NEUTRAL FLOWERING (DNF), from a normal Arabidopsis plant and introduced it into the mutant plant to restore its normal flowering response to day length.
The role of DNF in normal plant flowering is to regulate the CONSTANS gene. CONSTANS is activated only in the light and the plant is triggered to flower when CONSTANS levels rise above a certain threshold level during the daytime.

In normal plants, DNF represses the levels of CONSTANS until the day length is long enough and conditions are favourable for the survival of their seedlings. In mutant plants without an active DNF gene, CONSTANS is not repressed and they are able to flower earlier in the year, when days are still short.

The presence of the DNF gene has not yet been identified in species other than Arabidopsis but the scientists believe their on-going work may prove to have a wider significance for other species.
Scientists can override complex pathways that control flowering by artificially inducing or inhibiting key flowering genes such as DNF and CONSTANS. This can already be done in the laboratory by spraying an 'inducing agent' onto plants, stimulating them to flower early.

This could be used to extend the length of the harvesting season or to co-ordinate flowering or fruit production to a specific time. Growers already regulate the flowering of a few plants such as Chrysanthemum and Poinsettia, the latter specifically for Christmas and Easter.

Unravelling the complex pathways that control plant flowering will help scientists to understand and influence flowering patterns more effectively and in many different species.

In winter or early spring, Arabidopsis plants without an active DNF gene are already flowering (right). Those with the DNF gene will delay flowering until later in the year when days are longer and conditions are more favorable for survival of their seedlings (left). (Credit: Dr Steve Jackson)

Bacteria Provide Example of One of Nature's First Immune Systems, Research Shows

His findings, which appear in Nature Communications, a multidisciplinary publication dedicated to research in all areas of the biological, physical and chemical sciences, shed light on how bacteria have throughout the course of millions of years developed resistance to antibiotics by co-opting the DNA of their natural enemies -- viruses.

The battle between bacteria and bacteria-eating viruses, Wood explains, has been going on for millions of years, with viruses attempting to replicate themselves by -- in one approach -- invading bacteria cells and integrating themselves into the chromosomes of the bacteria. When this happens a bacterium makes a copy of its chromosome, which includes the virus particle. The virus then can choose at a later time to replicate itself, killing the bacterium -- similar to a ticking time bomb, Wood says.

However, things can go radically wrong for the virus because of random but abundant mutations that occur within the chromosome of the bacterium. Having already integrated itself into the bacterium's chromosome, the virus is subject to mutation as well, and some of these mutations, Wood explains, render the virus unable to replicate and kill the bacterium.

With this new diverse blend of genetic material, Wood says, a bacterium not only overcomes the virus' lethal intentions but also flourishes at a greater rate than similar bacteria that have not incorporated viral DNA.
"Over millions of years, this virus becomes a normal part of the bacterium," Wood says. "It brings in new tricks, new genes, new proteins, new enzymes, new things that it can do. The bacterium learns how to do things from this.
"What we have found is that with this new viral DNA that has been trapped over millions of years in the chromosome, the cell has created a new immune system," Wood notes. "It has developed new proteins that have enabled it to resists antibiotics and other harmful things that attempt to oxidize cells, such as hydrogen peroxide. These cells that have the new viral set of tricks don't die or don't die as rapidly."

Understanding the significance of viral DNA to bacteria required Wood's research team to delete all of the viral DNA on the chromosome of a bacterium, in this case bacteria from a strain of E. coli. Wood's team, led by postdoctoral researcher Xiaoxue Wang, used what in a sense could be described as "enzymatic scissors" to "cut out" the nine viral patches, which amounted to precisely removing 166,000 nucleotides. Once the viral patches were successfully removed, the team examined how the bacterium cell changed. What they found was a dramatically increased sensitivity to antibiotics by the bacterium.

While Wood studied this effect in E. coli bacteria, he says similar processes have taken place on a massive, widespread scale, noting that viral DNA can be found in nearly all bacteria, with some strains possessing as much as 20 percent viral DNA within their chromosome.

"To put this into perspective, for some bacteria, one-fifth of their chromosome came from their enemy, and until our study, people had largely neglected to study that 20 percent of the chromosome," Wood says. "This viral DNA had been believed to be silent and unimportant, not having much impact on the cell.
"Our study is the first to show that we need to look at all bacteria and look at their old viral particles to see how they are affecting the bacteria's current ability to withstand things like antibiotics. If we can figure out how the cells are more resistant to antibiotics because of this additional DNA, we can perhaps make new, effective antibiotics."

Single gram-negative Escherichia coli bacterium. Studying how bacteria incorporate foreign DNA from invading viruses into their own regulatory processes, Thomas Wood, professor in the Artie McFerrin Department of Chemical Engineering at Texas A&M University, is uncovering the secrets of one of nature's most primitive immune systems. (Credit: Janice Haney Carr)

When the Black Hole Was Born: Astronomers Identify the Epoch of the First Fast Growth of Black Holes

Now a team of astronomers from Tel Aviv University, including Prof. Hagai Netzer and his research student Benny Trakhtenbrot, has determined that the era of first fast growth of the most massive black holes occurred when the universe was only about 1.2 billion years old -- not two to four billion years old, as was previously believed -- and they're growing at a very fast rate.

The results will be reported in a new paper soon to appear in The Astrophysical Journal.

The oldest are growing the fastest
The new research is based on observations with some of the largest ground-based telescopes in the world: "Gemini North" on top of Mauna Kea in Hawaii, and the "Very Large Telescope Array" on Cerro Paranal in Chile. The data obtained with the advanced instrumentation on these telescopes show that the black holes that were active when the universe was 1.2 billion years old are about ten times smaller than the most massive black holes that are seen at later times. However, they are growing much faster.

The measured rate of growth allowed the researchers to estimate what happened to these objects at much earlier as well as much later times. The team found that the very first black holes, those that started the entire growth process when the universe was only several hundred million years old, had masses of only 100-1000 times the mass of the sun. Such black holes may be related to the very first stars in the universe. They also found that the subsequent growth period of the observed sources, after the first 1.2 billion years, lasted only 100-200 million years.

The team found that the very first black holes -- those that started growing when the universe was only several hundred million years old -- had masses of only 100-1000 times the mass of the sun. Such black holes may be related to the very first stars in the universe. They also found that the subsequent growth period of these black holes, after the first 1.2 billion years, lasted only 100-200 million years.

The new study is the culmination of a seven year-long project at Tel Aviv University designed to follow the evolution of the most massive black holes and compare them with the evolution of the galaxies in which such objects reside.

Other researchers on the project include Prof. Ohad Shemmer of the University of North Texas, who took part in the earlier stage of the project as a Ph.D student at Tel Aviv University, and Prof. Paulina Lira, from the University of Chile.

Illustration of a black hole and its surrounding disk. (Credit: NASA)

The finding has implications for understanding future climate change because dust plays a significant role in controlling the amount of solar energy in the atmosphere. Depending on their size and other characteristics, some dust particles reflect solar energy and cool the planet, while others trap energy as heat.

"As small as they are, conglomerates of dust particles in soils behave the same way on impact as a glass dropped on a kitchen floor," Kok says. "Knowing this pattern can help us put together a clearer picture of what our future climate will look like."

The study may also improve the accuracy of weather forecasting, especially in dust-prone regions. Dust particles affect clouds and precipitation, as well as temperatures.

The research was supported by the National Science Foundation, which sponsors NCAR.

Shattered soil
Kok's research focused on a type of airborne particle known as mineral dust. These particles are usually emitted when grains of sand are blown into soil, shattering dirt and sending fragments into the air. The fragments can be as large as about 50 microns in diameter, or about the thickness of a fine strand of human hair.

The smallest particles, which are classified as clay and are as tiny as 2 microns in diameter, remain in the atmosphere for about a week, circling much of the globe and exerting a cooling influence by reflecting heat from the Sun back into space. Larger particles, classified as silt, fall out of the atmosphere after a few days. The larger the particle, the more it will tend to have a heating effect on the atmosphere.

Kok's research indicates that the ratio of silt particles to clay particles is two to eight times greater than represented in climate models.

Since climate scientists carefully calibrate the models to simulate the actual number of clay particles in the atmosphere, the paper suggests that models most likely err when it comes to the number of silt particles. Most of these larger particles swirl in the atmosphere within about 1,000 miles of desert regions, so adjusting their quantity in computer models should generate better projections of future climate in desert regions, such as the southwestern United States and northern Africa.

Additional research will be needed to determine whether future temperatures in those regions will increase more or less than currently indicated by computer models.

The study results also suggest that marine ecosystems, which draw down carbon dioxide from the atmosphere, may receive substantially more iron from airborne particles than previously estimated. The iron enhances biological activity, benefiting ocean food chains, including plants that take up carbon during photosynthesis.

In addition to influencing the amount of solar heat in the atmosphere, dust particles also get deposited on mountain snowpacks, where they absorb heat and accelerate melt.

Glass and dust: Common fracture patterns
Physicists have long known that certain brittle objects, such as glass or rocks, and even atomic nuclei, fracture in predictable patterns. The resulting fragments follow a certain range of sizes, with a predictable distribution of small, medium, and large pieces. Scientists refer to this type of pattern as scale invariance or self-similarity.

Physicists have devised mathematical formulas for the process by which cracks propagate in predictable ways as a brittle object breaks. Kok theorized that it would be possible to use these formulas to estimate the range of dust particle sizes. He turned to a 1983 study by Guillaume d'Almeida and Lothar Schüth from the Institute for Meteorology at the University of Mainz in Germany that measured the particle size distribution of arid soil.

By applying the formulas for fracture patterns of brittle objects to the soil measurements, Kok determined the size distribution of emitted dust particles. To his surprise, the formulas described measurements of dust particle sizes almost exactly.

"The idea that all these objects shatter in the same way is a beautiful thing, actually," Kok says. "It's nature's way of creating order in chaos."

Dust particles in the atmosphere range from about 0.1 microns to 50 microns in diameter (microns are also known as micrometers, abbreviated as µm). The size of dust particles determines how they affect climate and weather, influencing the amount of solar energy in the global atmosphere as well as the formation of clouds and precipitation in more dust-prone regions. The NASA satellite image in this illustration shows a 1992 dust storm over the Red Sea and Saudi Arabia. (Credit: Copyright UCAR)

Ever-Sharp Urchin Teeth May Yield Tools That Never Need Honing

The rock-boring behavior is astonishing, scientists agree, but what is truly remarkable is that, despite constant grinding and scraping on stone, urchin teeth never, ever get dull. The secret of their ever-sharp qualities has puzzled scientists for decades, but now a new report by scientists from the University of Wisconsin-Madison and their colleagues has peeled back the toothy mystery.

Writing in the journal Advanced Functional Materials, a team led by UW-Madison professor of physics Pupa Gilbert describes the self-sharpening mechanism used by the California purple sea urchin to keep a razor-sharp edge on its choppers.

The urchin's self-sharpening trick, notes Gilbert, is something that could be mimicked by humans to make tools that never need honing.

"The sea urchin tooth is complicated in its design. It is one of the very few structures in nature that self-sharpen," says Gilbert, explaining that the sea urchin tooth, which is always growing, is a biomineral mosaic composed of calcite crystals with two forms -- plates and fibers -- arranged crosswise and cemented together with super-hard calcite nanocement. Between the crystals are layers of organic materials that are not as sturdy as the calcite crystals.
"The organic layers are the weak links in the chain," Gilbert explains. "There are breaking points at predetermined locations built into the teeth. It is a concept similar to perforated paper in the sense that the material breaks at these predetermined weak spots."

The crystalline nature of sea urchin dentition is, on the surface, different from other crystals found in nature. It lacks the obvious facets characteristic of familiar crystals, but at the very deepest levels the properties of crystals are evident in the orderly arrangement of the atoms that make up the biomineral mosaic teeth of the sea urchin.

To delve into the fundamental nature of the crystals that form sea urchin teeth, Gilbert and her colleagues used a variety of techniques from the materials scientist's toolbox. These include microscopy methods that depend on X-rays to illuminate how nanocrystals are arranged in teeth to make the sea urchins capable of grinding rock. Gilbert and her colleagues used these techniques to deduce how the crystals are organized and melded into a tough and durable biomineral.

Knowing the secret of the ever-sharp sea urchin tooth, says Gilbert, could one day have practical applications for human toolmakers. "Now that we know how it works, the knowledge could be used to develop methods to fabricate tools that could actually sharpen themselves with use," notes Gilbert. "The mechanism used by the urchin is the key. By shaping the object appropriately and using the same strategy the urchin employs, a tool with a self-sharpening edge could, in theory, be created."

The new research was supported by grants from the U.S. Department of Energy and the National Science Foundation. In addition to Gilbert, researchers from the University of California, Berkeley; Argonne National Laboratory; the Weizmann Institute of Science; and the Lawrence Berkeley National Laboratory contributed to the report.

Sea urchin teeth are pictured in situ. New research by Pupa Gilbert, a physics professor at the University of Wisconsin-Madison, and her colleagues reveals how the sea urchin's teeth are always sharp, despite constant grinding and scraping to create the nooks that protect the marine animal from predators and crashing waves. (Credit: Photo courtesy of Pupa Gilbert)

Big Quakes Trigger Small Quakes.

An earthquake in Alaska could trigger one near you, even if you're not in an earthquake-prone area, new research shows. Seismologists are now finding earthquakes in some unexpected places.

City Hall in Park City, Utah, is undergoing a $10 million seismic update. Park City is near the Wasatch Fault, an area overdue for an earthquake, so leaders have been concerned about earthquake-proofing the building for years. "It's something we absolutely expect," said Ron Ivie, a building official in Park City. "The question is, 'What day?'"

While earthquakes along fault lines are expected, seismologist Kris Pankow and her research team recently found slow-moving seismic surface waves, or L waves, from large earthquakes travel along the ground and trigger smaller earthquakes as they go.

"It's sort of like if a tree falls in the forest, does anyone hear it?" said Pankow, assistant director of the University of Utah seismic stations in Salt Lake City. "The same question was here: If the seismic waves go by everywhere, do they generate earthquakes everywhere?"

Unlike the earthquake risk in Park City, Pankow says the risk of these smaller earthquakes is minimal. The team tracked 15 large earthquakes and found 12 of them actually triggered smaller jolts. These are different than aftershocks because they happen miles away and sometimes hours or days later.

The team also found earthquakes in unlikely places like Canada, Australia and western Africa.

Pankow doesn't want to alarm anyone. She says the triggered earthquakes that have been observed have been small. Without a seismograph, you may not even notice them.

Seismologists still don't completely understand why earthquakes happen. Pankow and her team hope their work with these dynamically triggered earthquakes will help lead to an answer.

WHAT CAUSES EARTHQUAKES? An earthquake is the result of a sudden release of stored energy in the Earth's crust triggered by shifting tectonic plates. The Earth's lithosphere is an elaborate network of interconnected plates that move constantly -- far too slow for us to be aware of them, but moving, nonetheless. Occasionally they lock up at the boundaries, and this creates frictional stress. When that strain becomes too large, the rocks give way and break and slide along fault lines. This can give rise to a violent displacement of the Earth's crust, which we feel as vibrations or tremors as the pent-up energy is released. However, only 10% or so of the total energy is released in the seismic waves. However, the rest is converted into heat, used to crush and deform rock, or released as friction.

HOW DO SCIENTISTS RATE EARTHQUAKES? An earthquake's magnitude describes how much the ground moves. The scale is logarithmic, which means that when the magnitude increases by one (say from 3 to 4, or from 4 to 5) the amount of ground motion increases by ten times. That is, a magnitude 3 quake leads to ten times as much ground motion as a magnitude 2 quake, and a magnitude 2 leads to ten times as much motion as a magnitude 1. This means that a magnitude 3 is a hundred times as violent as a magnitude 1, and a hundred times less violent than a magnitude 5.

The magnitude scale also tells us just how much energy an earthquake released. For example, a magnitude 1 earthquake releases the same amount of energy as 30 pounds of TNT exploding. Although a magnitude 2 earthquake makes the ground move ten times as much as a magnitude 1, it releases 32 times as much energy -- or roughly as much as a ton of TNT. A magnitude 5 earthquake packs the punch of a moderate nuclear weapon, and a magnitude 12 quake would be enough to put a crack all the way through the center of the Earth.

System for Detecting Noise Pollution in the Sea and Its Impact on Cetaceans

In 2007, the Applied Bioacoustics Laboratory started work on a project called Listening to the Deep Ocean Environment (LIDO). It set out to record sounds on the seafloor and subsequently assess the extent to which artificial noises (maritime traffic, fishing, offshore facilities, military maneuvers, etc.) affect the quality of life of cetaceans in terms of any disorders they may suffer, or even their deaths.

Under the supervision of Michel André, the Applied Bioacoustics Laboratory (LAB) has now developed algorithms that automatically interpret these sounds, classify them in real time by their biological or anthropogenic origins and, within this division, the species of cetaceans present in the area analyzed are identified. Using the data obtained, it is possible to measure the extent to which noise pollution has an impact on the conservation of ecosystems.

This is the first system of its kind in the world and saves considerable analysis time and human resources in the detection and classification of noise, as these processes are completely automated. Thus, the technology prevents a continuous flow of unanalyzed acoustic data from overloading hard drives at research centers. Before now, this was one of the problems in processing uninterrupted data streams.

Finally, the acoustic signals and the result of the analysis can be listened to and seen live over a website that is available to the international scientific community and to laypersons

The importance of noise in the sea
There has always been natural and biological noise in the sea. However, the recent, uncontrolled introduction of artificial noise in the sea on an unprecedented scale poses an even greater threat to its equilibrium than any other source of pollution in the marine environment.

The sense of hearing is vital to cetaceans, as they use it to find prey, navigate in the sea, migrate and distinguish members of the same species. Therefore, their survival depends on their sense of hearing working properly.

Using a set of 13 hydrophones installed in over 10 underwater platforms located all over the world, the UPC's system detects the presence of cetaceans and enables scientists to study the relationship these animals have with other mammals in their habitat. This innovative system therefore opens unexplored avenues in the biological study of these species. However, the importance of the LIDO project lies in the possibility of better understanding the sensitivity of cetaceans to sources of noise pollution, detect the interaction of these animals with human activity and, more importantly, it will make it possible to take decisions for mitigating noise when the lives of these mammals are threatened.

To date, the increase in beached whales, sperm whales and other cetaceans around the world has been put down to the greater noise levels caused by fishing, sea trade, military maneuvers, and the construction of oilrigs and offshore wind farms. Thanks the technology developed by the UPC's research team, based on the Vilanova i la Geltrú Campus, it will now be possible to accurately ascertain whether there is a direct cause and effect relationship between the two events.

Based in this information, governments, institutions and businesses that operate in the sea will be able to establish response protocols to prevent these species from falling victim to exposure to noise of an anthropogenic origin that may cause damage to their hearing and, therefore, an imbalance in marine ecosystems.

First step for regulating noise pollution in the sea
The LAB has in fact written a manual of good practices for managing noise pollution in the sea at the request of the Ministry of the Environment and Rural and Marine Affairs, within the framework of the eCREM (Effects and Control of Anthropogenic Noise in Marine Ecosystems) project. The manual is the first step for drawing up a draft bill and good practices to regulate noise pollution in the sea in Spain, which is one of the first countries in the EU that intends to introduce regulations to this regard.

It should be taken into account that forecasts show that maritime traffic in the Mediterranean basin will increase significantly over the next few years to mitigate the atmospheric pollution derived from the transport of goods by road. The new EU directive on the sea rules that all member states must comply with a set of indicators for measuring marine noise pollution before 2012. A group of 11 experts from around Europe, one of whom is Michel André, the director of the LAB, are currently working to establish exactly which indicators are to be used.

The LAB has planned to develop alarm technologies in the near future. They are to be installed on various devices, such as autonomous buoys and underwater robots, which would send off warnings that cetaceans are approaching areas with high noise levels and set off response protocols.
The UPC team has devoted 15 years to the study of noise pollution in the sea and to the creation of technological solutions that make it possible to combine human activities and the interests of industry with the conservation of cetaceans and the marine environment.

The LAB is placing particular emphasis on the study of the effects of noise pollution on cetaceans because these marine mammals are at the top of the food chain, and their activities depend on the exchange of acoustic information. Therefore, their reaction to sources of noise pollution helps to determine the general state of marine environments. Cetaceans are considered to be bioindicators of the acoustic balance in oceans.

International network of underwater observatories
The LIDO platform, which records underwater noise in different parts of Europe and North America, is open to the international scientific community.
Noise sources are detected by hydrophones installed on over 10 underwater observatories. Some of the LIDO sensors have been deployed on the European Seafloor Observatory Network (ESONET), one of whose members is the UPC's Expandable Seafloor Observatory (OBSEA) located on the coast of Vilanova i la Geltrú. The LAB has another set of sensors installed in the deep sea infrastructures of the ANTARES project, an international collaboration that focuses on detecting subatomic particles called neutrinos, which move through space without being stopped by matter. Finally, there are another three hydrophones in North America on the seafloor platforms of the NEPTUNE network in Canada.

The LAB is in the final stages of reaching an agreement with Japan to install the technology on 17 platforms designed to detect the risk of earthquakes in the Asian archipelago.

Listening to the Deep Ocean Environment (LIDO) website. (Credit: Image courtesy of Universitat Politècnica de Catalunya)