Chiral blastomere arrangement dictates zygotic left–right asymmetry pathway in snails

Most animals display internal and/or external left–right asymmetry. Several mechanisms for left–right asymmetry determination have been proposed for vertebrates^{1, 2, 3, 4, 5, 6, 7, 8, 9, 10} and invertebrates^{1, 2, 4, 9, 11, 12, 13, 14} but they are still not well characterized, particularly at the early developmental stage. The gastropods Lymnaea stagnalis and the closely related Lymnaea peregra have both the sinistral (recessive) and the dextral (dominant) snails within a species and the chirality is hereditary, determined by a single locus that functions maternally^{15, 16, 17, 18}. Intriguingly, the handedness-determining gene(s) and the mechanisms are not yet identified. Here we show that in L. stagnalis, the chiral blastomere arrangement at the eight-cell stage (but not the two- or four-cell stage) determines the left–right asymmetry throughout the developmental programme, and acts upstream of the Nodal signalling pathway. Thus, we could demonstrate that mechanical micromanipulation of the third cleavage chirality (from the four- to the eight-cell stage) leads to reversal of embryonic handedness. These manipulated embryos grew to 'dextralized' sinistral and 'sinistralized' dextral snails—that is, normal healthy fertile organisms with all the usual left–right asymmetries reversed to that encoded by the mothers' genetic information. Moreover, manipulation reversed the embryonic nodal expression patterns. Using backcrossed F₇ congenic animals, we could demonstrate a strong genetic linkage between the handedness-determining gene(s) and the chiral cytoskeletal dynamics at the third cleavage that promotes the dominant-type blastomere arrangement. These results establish the crucial importance of the maternally determined blastomere arrangement at the eight-cell stage in dictating zygotic signalling pathways in the organismal chiromorphogenesis. Similar chiral blastomere configuration mechanisms may also operate upstream of the Nodal pathway in left–right patterning of deuterostomes/vertebrates.

ational design of a structural and functional nitric oxide reductase

Protein design provides a rigorous test of our knowledge about proteins and allows the creation of novel enzymes for biotechnological applications. Whereas progress has been made in designing proteins that mimic native proteins structurally^{1, 2, 3}, it is more difficult to design functional proteins^{4, 5, 6, 7, 8}. In comparison to recent successes in designing non-metalloproteins^{4, 6, 7, 9, 10}, it is even more challenging to rationally design metalloproteins that reproduce both the structure and function of native metalloenzymes^{5, 8, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20}. This is because protein metal-binding sites are much more varied than non-metal-containing sites, in terms of different metal ion oxidation states, preferred geometry and metal ion ligand donor sets. Because of their variability, it has been difficult to predict metal-binding site properties in silico, as many of the parameters, such as force fields, are ill-defined. Therefore, the successful design of a structural and functional metalloprotein would greatly advance the field of protein design and our understanding of enzymes. Here we report a successful, rational design of a structural and functional model of a metalloprotein, nitric oxide reductase (NOR), by introducing three histidines and one glutamate, predicted as ligands in the active site of NOR, into the distal pocket of myoglobin. A crystal structure of the designed protein confirms that the minimized computer model contains a haem/non-haem Fe_B centre that is remarkably similar to that in the crystal structure. This designed protein also exhibits NO reduction activity, and so models both the structure and function of NOR, offering insight that the active site glutamate is required for both iron binding and activity. These results show that structural and functional metalloproteins can be rationally designed in silico.

Cancer-associated IDH1 mutations produce 2-hydroxyglutarate

Mutations in the enzyme cytosolic isocitrate dehydrogenase 1 (IDH1) are a common feature of a major subset of primary human brain cancers. These mutations occur at a single amino acid residue of the IDH1 active site, resulting in loss of the enzyme's ability to catalyse conversion of isocitrate to -ketoglutarate. However, only a single copy of the gene is mutated in tumours, raising the possibility that the mutations do not result in a simple loss of function. Here we show that cancer-associated IDH1 mutations result in a new ability of the enzyme to catalyse the NADPH-dependent reduction of -ketoglutarate to R(-)-2-hydroxyglutarate (2HG). Structural studies demonstrate that when arginine 132 is mutated to histidine, residues in the active site are shifted to produce structural changes consistent with reduced oxidative decarboxylation of isocitrate and acquisition of the ability to convert -ketoglutarate to 2HG. Excess accumulation of 2HG has been shown to lead to an elevated risk of malignant brain tumours in patients with inborn errors of 2HG metabolism. Similarly, in human malignant gliomas harbouring IDH1 mutations, we find markedly elevated levels of 2HG. These data demonstrate that the IDH1 mutations result in production of the onco-metabolite 2HG, and indicate that the excess 2HG which accumulates in vivo contributes to the formation and malignant progression of gliomas.

Coral Cove Park and the Blowing Rocks Preserve: The Little Sur

The Experience

It's 3:30 a.m. and I wake to the sound of my cell phone's alarm. The smell of the freshly brewed coffee is the start of a day that I have been looking forward to for a while. Today, I visit the Blowing Rocks!

I dread making the phone call to my shooting buddy, Paul, who is definitely not a morning person, but he wants to go anyway. After a couple of rings, a comatose voice answers, "Huh?"

I yell out on the phone, "I'm on my way, get up!"

I kiss my wife good-bye and I'm gone. The excitement that I feel almost makes the coffee unnecessary, yet the 2 hours on the road have me thinking that teleportation would be an awesome creation. Suddenly, the annoying voice of my GPS alerts me that I am nearing my destination. Yes! After the long, dark, boring ride, we're finally here!

As we unload the gear from the car, we hear a thunderous rumble. Then we hear another... and another. We can't help but think that the thunderstorms will probably block our sunrise. But we're here, and we might as well make the best of it. As we make our way over the dunes, we are welcomed by perfect conditions. The first bit of twilight just barely lets us make out the perfectly placed clouds. The thunderous sounds we heard were actually waves crashing violently against the largest rock formations I had ever seen on any Florida coast. At the same time, I also knew that this was not the Blowing Rocks Preserve. These rocks are much smaller. This was, in fact, Coral Cove Park and it was so interesting that we decided to do our shooting here. It just seemed like a sure thing.

Daylight was coming and the sun, although still below the horizon, blessed the sky with shades of magenta, pink, orange and blue. The color of the clouds almost perfectly matches the colors of the rocks. The crashing waves make for a nice fog over the surface of the water in our photos, as we experiment with long exposures. Setting up a tripod can be pretty tricky as the rocks are pitted by hundreds, even thousands of years of erosion. The smooth, reddish-colored rock formations seem to have somewhat of a sandstone appearance, but it is actually anastasia limestone. The waves splash large volumes of water up onto the rocks and as the water recedes, they make an abundance of tiny "waterfalls" which also add a bit of interest to the images we capture. The salt mist creates a natural Orton effect on my ND grad filter, though after a while, it can prove to be a bit too much. All of the crevices, boulders, miniature canyons, blowholes and seashells provide a photographer with so many compositions that it can almost be overwhelming. It's such a great place that it's difficult to stay in just one spot. If only the sun could slow it's ascent, then I could take the time I need to make all these images work. Those are the little things that have me looking forward to my next few trips, though. No two sunrises are ever the same and each trip is a new lesson and a new experience.

The Real Blowing Rocks

On the next trip, we shot sunrise at Coral Cove Park again. It's a summer day with another great sky and the fantastic breeze made it feel like we were still in March. Wispy clouds colored up in a reddish tone and though the waves were still crashing, the tide was lower and the seas were slightly calmer than our last visit. The low tide left behind pools in the craters of the rocks. As I set up the tripod for my next composition, I noticed that one of these pools had trapped a hatchling loggerhead sea turtle. He appeared exhausted, so I took him out of the hole. Paul and I fired off a few shots of the hatchling as he rested. When he seemed to gain enough energy to make his way back toward the ocean, we took him to an area without rocks and set him free at the shoreline. I sure hope he made it.

The sun finally made its way over the horizon, and after wiping down our camera gear with rags dampened with fresh water, we decided to take the 1.25-mile hike up the beach to the Blowing Rocks Preserve. This hike looks much easier than it is. Loosely packed sand and heavy camera gear make the short hike feel like it was over 3 miles uphill. With our calves aching and my lower back in a knot, we finally make it. The preserve has a much easier way to get in, a front door, but they don't open until 9:30 a.m. and we were still an hour away from that time. The tide was not high, but not low either. Though the light was a bit too harsh for my taste, I took the time to scan and photograph the area to scout for possible compositions in the future. At the top of the cliffs, where less erosion takes place, the limestone is a lot more like jagged limestone should be. Walking barefoot was almost worse than the pinnacle rock that I often encounter on my Everglades ventures. Just a little tip: Don't leave your shoes behind!

This area is beautiful! The condominiums that line the coast suddenly cease and for a good stretch of the beach, we are now surrounded by nature. Over the next couple of high-tide visits, I witness the spectacle that gives the area its descriptive name. Strong winds and big waves send water gushing up 40 to 50 feet in the air. Air and water rushing through some of the narrower holes make a barking sound that had me looking for a dog along the beach. Photographer and NPN editor, Richard Bernabe pointed out that the blowholes were working in a sequence as the waves roll in at a slight angle. That was a real show in itself. Although it may be difficult to emphasize this sequence in a photo, the new HD video capable DSLRs would be a great tool to show this off.

Low tide may also present fantastic photo opportunities. A lower tide exposes smaller rocks that would normally be submerged while allowing photographers to shoot from below, showing off the height of the 2 story cliffs in their images. The early morning glow lights up these cliff walls beautifully and this low angle may provide depth to your images. Don't risk it though. If the low tide is not exposing sand, stay away from the cliffs. Rogue waves are common here and they can send you crashing up against the rocks, costing you your gear and possibly your life.

The History

Blowing Rocks is a part of Jupiter Island, which separates the Atlantic Ocean from the Indian River Lagoon. The Blowing Rocks Preserve is now owned and managed by The Nature Conservancy. Although development has taken up much of Jupiter Island, it was actually the island's residents who decided that the area was so beautiful and unique, that it needed protection. They purchased the land and donated it to The Nature Conservancy in 1969. The Nature Conservancy is now working on restoring the 73-acre area of its native plants and protecting this fragile ecosystem.

Residents and visitors both literally and metaphorically walk on eggshells when it comes to coexisting with nature here. This stretch of coast is a very important nest area for three species of sea turtles. Loggerhead, Atlantic Green and the largest of all, the Leatherback sea turtles use this coast for nesting as they have for millennia. During summer months, the sea turtles' struggle for survival is obvious. Hatchlings race toward the water as sea gulls, pelicans, osprey and other native birds try to pick them off. Once in the water, in addition to the birds, all sorts of marine animals now become a threat to the hatchlings. Sometimes the eggs themselves aren't safe. Take a walk down the beach and look for small craters in the sand. You may notice that the craters are surrounded with raccoon prints. Upon closer inspection, you may also notice that some of the broken eggshells still have baby turtles in them that would have otherwise been many days away from hatching. It's a sad situation, but it's nature. This is why sea turtles lay so many eggs. Only one in every hundred makes it through their first year. Humans could make matters worse, but fortunately in this case, the folks at The Nature Conservancy and the caring residents are there to help.

Photography at the Blowing Rocks

This is a fantastic place to get some very unique images, but there are concerns for photographers as well. We are nothing without our photography equipment. Don't let the hazardous conditions have you packing up and leaving early.

Salt water is a killer when it comes to electronics. Crashing waves can wet your gear, causing it to act funny. Even weather-resistant cameras can short out or otherwise malfunction. Make sure you take plenty of lens cloths and rags with you. Keep one handy and make sure the others are kept dry in your camera bag. You will have to change them pretty often. Play it safe and don't give the saltwater a chance to seep into any openings in your electronic gear. Check your lens often as well. Make sure you have no drops on it, which could be a pain in the neck to clone out later.

A tripod is absolutely necessary. Just make sure to rinse it in freshwater when you are done. Coral Cove Park has freshwater showers available near the restroom and playground area.

Do you prefer using ND grads, or blending two to three exposures? I do both, depending on the situation. When shooting at Blowing Rocks Preserve or Coral Cove Park, I find it easier to use a grad. They allow you to catch the action in the water and waves without having to deal with the cumbersome blending process. Blending the images can be tricky with the water movement and splashing waves, especially when using shutter speeds from 1/4 sec. to 2 seconds. Long exposures will completely blur the water, giving it a misty or foggy appearance. Because most of the texture in the water is lost, blending together two long exposures is relatively easy.

Is the weather not what you expected? Make the best of it! Sunrise isn't your only option. If the clouds give way to the sun on the west, with clouds on the east, the colors can be spectacular as sunset approaches. Even if the opposite occurs, look out for a display of anti-crepuscular rays on the east. Even thunderstorms can provide you with a really dramatic sky. With slow enough shutter speeds and a little bit of luck, maybe you'll get some lightning in the image as well.

On your next visit to South Florida, this may be a place of interest to you. It's not what you may expect from the Florida coast, but that's what makes it worthwhile photo shoot. And while it might lack some of the drama of California�s Big Sur, it�s a beautiful place nonetheless. Think of it as �Little Sur!�

Blowing Rocks Preserve is located about half an hour north of West Palm Beach at 574 South Beach Road, Hobe Sound, Florida. The preserve can be contacted at (561) 744-6668.

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Overfishing linked to algal blooms

Depletion of large predatory fish disrupts food chain.

Matt Kaplan

Predatory pike can ultimately help to control algal blooms.Photolibrary

Nitrogenous fertilizers and detergents have long been known to cause algal blooms that block sunlight and strangle ecosystems, but a study now reveals that overfishing of large predatory fish is also playing a key part.

Britas Klemens Eriksson at the University of Groningen in the Netherlands noticed that populations of predatory fish in the Baltic Sea seemed to be declining in areas where algal blooms subsequently tended to form. Curious as to whether there was a connection, Eriksson and a team of colleagues from the Swedish Board of Fisheries in Öregrund set up an investigation.

The team reviewed a year's worth of field data on predatory pike (Esox lucius) and perch (Perca fluviatilis) populations from nine areas covering 700 kilometres of coastline in the Baltic Sea. They then compared this information with information collected during the same period on smaller fish and algal populations in the region. They found some intriguing patterns.

"In areas where there were strong declines in perch and pike there were massive increases in smaller fish and large blooms of algae," comments Eriksson. Where perch and pike populations were intact, the surrounding waters had a 10% chance of experiencing an algal bloom; in areas where their populations had been substantially reduced, the chances of an algal bloom were 50%.

Intrigued by these trends, the researchers ran small-scale field experiments for 2 years in unpolluted waters to investigate the forces responsible for controlling algal growth. They manipulated the environmental conditions in these experiments by: sometimes excluding large predatory fish through the use of cages; sometimes adding nitrogenous fertilizer pellets; sometimes applying both techniques; and sometimes leaving areas as untouched controls.

As expected, the nitrogenous pellets increased algal growth. But surprisingly, when predatory fish were prevented from accessing a given area, algae in that area became much more prevalent. The effect even proved to be true when nitrogenous pellets were not added to the system.

"This is the first study to show that top predators are linked to the formation of macroalgal blooms," says marine biologist Heike Lotze, at Dalhousie University in Nova Scotia, Canada.

In tiers

Eriksson speculates that the effect results from the disruption in the food chain caused by excluding the large predator fish. Top-predatory fish feed on mid-level predatory fish, which in turn feed on invertebrate herbivores such as snails and crustaceans. These are the animals that control the algal community. Knock out the top predators, and mid-level predators develop huge populations which, in turn, reduce the numbers of algal-eating species, allowing blooms to grow unchecked, explains Eriksson.

The team report in Ecological Applications¹ that, on the basis of their findings, fighting algal blooms by more tightly controlling nitrogenous materials in waste water and agricultural run-off is not the best approach. "If we want to manage algal blooms effectively, we need to start by taking an ecosystem perspective … we have to restore depleted fish communities," says Eriksson.

"That they are showing effects over four trophic [feeding] levels is really impressive," says Lotze. "We've tried to experimentally explore these sorts of interactions before, but with so many levels there is often too much noise to see trends. That they've managed to get clear results is exciting."

Yet even with these results, nitrogenous material must not be ignored. "When we added nitrogen and removed predators we saw blooms that were two times larger than those created by predator depletion alone. The two certainly appear to be connected," says Eriksson.

This is an important finding, because environmental management programmes currently handle fish population conservation and algal-bloom control as separate entities. "Environmental practice has to change based upon these results," says experimental ecologist Birte Matthiessen at the Leibniz Institute of Marine Sciences in Kiel, Germany. "Eutrophication and fisheries management need to be combined."

Technology transfer on the table

Climate summit will seek ways to help developing nations build a low-carbon energy infrastructure.

Jeff Tollefson

To tackle climate change, poor countries may need green technologies, such as these wind turbines in India.A. Dave/Reuters

Cutting global carbon emissions and slowing climate change will require a massive dissemination of clean-energy technology from rich nations to the developing world. And although negotiators remain deadlocked over goals for cutting emissions (see page 550), they are converging on a framework for speeding up the spread of the necessary technologies.

Several proposals for this will be on the table when delegates from 192 countries gather in Copenhagen for the climate summit next week, but two elements seem to be gathering momentum in the run-up discussions. The first is the idea of a centralized technology-transfer body under the United Nations climate convention. The second is a network of regional centres, or some kind of technology corps, to help poor nations implement sustainable-development plans.

Both proposals sidestep the issue of access to patented technology, the focus of a long-running dispute between rich and poor nations. Instead, they would help poor countries address an array of mundane but in many ways more pernicious issues, such as energy infrastructure, government policy and workforce development, that hinder their ability to absorb new technologies. Blueprints for a solar thermal power station, for instance, aren't much use without qualified engineers to build and run it and power lines to carry the electricity — challenges even for industrialized nations.

"You have to come back to the basic question about how technology is flowing to the developing world, and it's primarily flowing through transactions within the business community," says Björn Stigson, president of the World Business Council for Sustainable Development in Geneva, Switzerland. Government policies, local economics and workforce issues can all affect those deals, he says. "The biggest bottleneck is availability of human resources."

Exactly how this new framework would function, what kind of authority it would have and how much money it would command remain to be worked out. But poor and rich countries alike support the general idea, says Kunihiko Shimada, a Japanese delegate who has stepped aside as a negotiator in order to co-chair the technology-transfer group at the UN climate talks.

“We need a proliferation of efforts and institutions, because we don’t know what is going to work.”

Shimada acknowledges that negotiators in Copenhagen could still get bogged down in the debate over access to the patented technologies found in everything from the latest solar panels to low-emission coal-plant prototypes. Developing countries have to varying degrees called for compulsory licensing, which would force companies to put certain patents in the public domain, or for a fund to purchase patented technologies, which would then be put in the public sphere. Industrialized countries are resisting such proposals, declaring that intellectual property is crucial to driving innovation.

In fact, little is known about how patents affect technological diffusion in the energy industry, when any given 'technology', such as a wind turbine or a clean coal plant, might contain dozens or hundreds of patents, many of which originated in other industries. "We are flying blind," says Bernice Lee, a researcher who has been studying the issue at Chatham House, a think tank in London.

Lee recently headed a Chatham House analysis of nearly 57,000 patents in six energy sectors, which found that the 30 most-cited patents in each sector took two to three decades to hit the mass market. That lag time will need to be halved by 2025 if the world is to meet its climate goals, according to the report. In order to disperse crucial technologies more quickly and widely, Chatham House recommends expanding global demonstration programmes for high-risk sectors such as carbon capture and storage, coordinating technology standards, and accelerating international collaboration on research and development.

All of these functions could be promoted through a technology-transfer body under the UN climate convention, although few think that will be enough to get the job done. "We need a proliferation of efforts and institutions, because we don't know what is going to work," says Michael Levi, a climate expert at the Council on Foreign Relations in New York City. "What we can't afford is to focus on a single mechanism and then find out over the course of a decade that it doesn't work very well."

The developing world, for its part, can't simply wait for the rich countries to equip it for a low-carbon future, says Shane Tomlinson, a researcher with the London-based advocacy group E3G, which promotes sustainable development. One proposal under discussion would require countries to create their own sustainable-development strategies, perhaps in concert with plans for adapting to climate change, to be eligible for international aid. "It's a balanced approach between top–down strategic prioritization and bottom–up low-carbon development plans that is really key to getting the marketplace right," Tomlinson says. "We really do need both."

Reuters

Climate analysts are praising China's promise to slash the country's emissions — even as they wonder if the target is achievable or ambitious enough.

Last week, China's State Council announced that the country will cut its carbon intensity — carbon emissions per unit of gross domestic product (GDP) — by 40–45% from 2005 levels by 2020. "It is a very welcome decision," says Fatih Birol, chief economist at the International Energy Agency in Paris. "If the target is met, it would have significant implications for China and the rest of the world."

Yet some think that the target is not far-reaching enough given China's booming economy and its track record of improving energy efficiency. The country reduced its energy intensity — energy consumption per unit of GDP — by 47% between 1990 and 2005, and looks likely to cut it by another 20% from 2005 levels by the end of next year. Carbon intensity can drop faster than energy intensity if clean-energy sources are brought into the mix.

Online collection

Xie Zhenhua, deputy director of China's National Development and Reform Commission, says that China has picked low-hanging fruit by closing energy-inefficient factories and power plants. In China, industry accounts for an unusually large share — 50% — of energy consumption. "The further we go, the more challenging and costly it will get," he says.

If China sticks to current policies, it will reduce its carbon intensity by about 30% by 2020, says Zou Ji, an environmental economist at Renmin University in Beijing. "To get extra mileage and reach the 40–45% target, China will have to instigate substantial social and economic reforms across the board," he says.

Indeed, the China Council for International Cooperation on Environment and Development (CCICED), a joint Chinese and international advisory board to the state government, recently laid out a road map to a low-carbon economy. It includes recommendations in such wide-ranging areas as energy pricing, industrial development, technological innovation, tax systems, land use and urban planning. "The daunting challenge that China faces cannot be underestimated," says Zou. "The concern is not only whether China is willing to make that step forward but whether its development state will allow a smooth economic transition."

Emissions peak

The new pledge will be included in China's next five-year plan along with policies to help it shift towards a low-carbon economy.

The target puts China on a path for emissions to peak around 2030, says Knut Alfsen, head of research at the Center for International Climate and Environmental Research in Oslo, and an author on the CCICED report. That peak, he says, "will take place at a level where emissions per capita are only half of what we have in the developed world today".

China's announcement came the day after US President Barack Obama pledged to cut his country's emissions by 17% from 2005 levels by 2020. It is the first time that the world's top two emitters have offered specific targets at the same time for controlling their emissions.

"It's very important for the two countries to put numbers on the table," says Jim Watson, a policy researcher at the University of Sussex in Brighton, UK.

In recent weeks other developing countries have made ambitious pledges. South Korea has promised a 30% cut below a business-as-usual scenario, and Brazil at least a 36% cut by 2020. Both would be modest cuts compared with 2005 emissions.

India followed China's announcement by saying it would "be willing to sign on to an ambitious global target for emissions reductions or limiting temperature increase" — but with the catch that "this must be accompanied by an equitable burden-sharing paradigm". China and India, along with Brazil, South Africa and Sudan, last weekend reiterated developing countries' insistence that developed nations help bear the cost of climate change, including facilitating technology transfer (see page 555).

So far, the European Union has pledged the most aggressive emissions cuts in the developed world, of 20% from 1990 levels by 2020, to be increased to 30% below if rich non-EU nations follow suit. The US target announced last week would be equivalent to a 3% reduction from 1990 levels.

Obama must also work with the Democrat-­dominated Congress to pass climate legislation that would make its targets binding. The 17% cut he announced last week is in agreement with a bill passed by the House of Representatives earlier this year. The Senate is expected to vote on its own version of climate legislation early in 2010. The Environmental Protection Agency has the authority to regulate carbon dioxide emissions if Congress does not act.