Population Fears
Scientists now predict that by the year 2050 the population will be doubled what is today. The fact remains that the rate of food production fell behind population growth in many of developing countries. The annual fish catch already exceeds what the world ‘s oceans can successfully sustain. If we go on using our natural recourses at today’s rates, we will have used up the intire reserves of cooper, natural gas and oil by the year 2054.
But the problem ahead lie not so much in what we use but in what we waste. What faces us is not so much a recourse crisis as a pollution crisis. The only solution is to try to change the areas of consumption, technology and population. Changes in technology must be baked by slower population growth. And it can be achieved by education in health and women’s rights. And there is a little hope of reducing consumption over the next half century.
(Source: http://www. popsci.com)
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TEXT 9. IMMIGRANT FOX ALTERS PLANT LIFE ON ALASKA ISLANDS
Foxes may not graze, but a new scientific study describes how their arrival on Aleutian islands destroyed rich grasslands and left only sparse tundra. The authors of the report say this transformation shows how an entire ecosystem may decline if just one new top carnivore shows up.
The inadvertent experiment began in the late 1700's and continued into the early 20th century as fur traders looking to expand the supply released nonnative arctic foxes and, in some cases, red foxes on more than 400 Alaskan islands.
The new habitats included much of the Aleutian archipelago that curves west toward Asia. Except for the occasional polar bear rafting on winter ice, the windswept islands had few predators before.
The botanical impoverishment that has resulted is the reverse of what usually happens when a new meat-eater comes along. "Traditionally, the predator eats the grazer; the grazer no longer eats the green stuff; and the habitat gets more green," said Dr. Donald Croll, a professor of biology at the University of California.
An example of the more usual routine is in Yellowstone National Park in the western United States, where returning wolves, preying on sapling-browsing elk and confining the wary survivors to areas where they can see wolves coming, have touched off a resurgence of willow, aspen and other vegetation.
The contrary effect in the Aleutians has a simple explanation. The grazers on these islands were grass- and seed-eating Aleutian geese. The foxes drove the geese near extinction, which would have been a boon for grasses except that the foxes also feasted on the eggs and hatchlings of puffins, auklets and other ocean-feeding seabirds they found brooding almost everywhere.
Some islands lost almost all birds except for cliff-nesting species. And as ground-nesting birds faded, so did their nutrient-rich excrement, or guano, which had been a natural fertilizer.
Without the regular subsidy of nitrogen and potassium-rich nutrients brought in from the sea, grasses lost their competitive edge over tundra shrubs and herbaceous plants.
Vernon Byrd, a Fish and Wildlife Service biologist, has been paying attention to one ecosystem for decades. Despite foxes, the islands remain home to more than 10 million sea-birds of 29 species. Mr. Byrd is an avid birder. For several years, Mr. Byrd and others in the refuge have been eradicating foxes with traps.
One of the cleanest islands is called Rat, which brings up another twist in a never-ending battle against alien, bird-eating Aleutian predators. Shipwrecks are not uncommon. When a vessel runs ashore, Fish and Wildlife personnel work as hard to protect the land as they do to protect the sea from their contents. Rodents can run amok in seabird colonies too or, as Mr. Byrd put it, "rat spills are a lot worse than oil spills in the long term".
(Source: http://www. popsci.com)
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TEXT 10. AFTER ROBOT-ASSISTED REHAB AND A DOSE OF CHEMICALS, PARALYZED RATS WALK AGAIN
Walking Again After neurorehabilitation with a combination of a robotic harness and electrical-chemical stimulation, a paralyzed rat takes its first steps up the stairs.
With careful training using a robotic harness, and a special chemical cocktail designed to stimulate brain cells, rats with spinal cord injuries were able to re-learn how to walk. Scientists in Switzerland say the tests suggest humans with paralysis due to spinal cord injuries may regain some nerve activity.
The therapy takes advantage of the nervous system’s inherent plasticity, in which neural networks can be rewired to take on different tasks. Areas of the motor cortex were able to establish new connections to the rats’ hind limbs, which had been paralyzed due to spinal cord injuries in a manner similar to spinal cord paralysis in people.
Despite the nervous system’s ability to reroute itself, half of human spinal cord injuries lead to paralysis, according to researchers led by Grégoire Courtine at the Swiss Federal Institute of Technology. But with a neural prosthesis, in this case an electrochemical treatment, and a robotic assistance device, even the most debilitating injury can be re-routed. The trick was rousing the dormant spinal column, the researchers say.
This is different from other robotically mediated paralysis therapy we saw recently involving brain-derived motor control. In that study, human patients wore a cranial device that tapped into their thoughts to control a robotic arm. In this case, the treatment is physiological, inducing dormant neurons to forge new connections and move limbs directly.
First, Courtine and colleagues injected the rats with a chemical cocktail that binds to dopamine, adrenaline and serotonin receptors on the spinal cord’s neurons. This replaced the neurotransmitters that would normally be released in healthy spinal pathways. A few minutes after priming the neurons, the team stimulated the rats' spinal cords through electrodes implanted into the spinal canal. This sent electrical signals to the roused neurons. Then the rats needed to be trained to use their limbs again. Within a week of their injuries, the rats were on treadmills, forging new neural connections.
Courtine and colleagues built a little rat vest that supported the animals as they stood on the treadmill. The vest stood them up on their hind legs, basically forcing them to use their paralyzed hind legs to walk upright. The rats tried to move toward a piece of chocolate on the other end, and gradually this “willpower-based training” built up new nerve fibers, the researchers say.
After two weeks of training, the rats took their first voluntary steps on their paralyzed legs. Within five or six weeks, all the rats in the study were able to walk bipedally, on their hind legs, for extended periods, Courtine et al. say.
“This is the world-cup of neurorehabilitation,” Courtine said in an EPFL news release. “Our rats have become athletes when just weeks before they were completely paralyzed. I am talking about 100 percent recuperation of voluntary movement.”
This is still a long way from working in humans, however. But human clinical trials are already on the horizon, set to start within two years in Zurich, according to EPFL.
(Source: http://www. popsci.com)
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TEXT 11. TOMATO GENOME DECODED, WILL SEED DEVELOPMENT OF TASTIER, FLESHIER FRUITS
A relatively small cluster of genetic information, some of it dating to 60 million years ago, endows the staple fruit of summer with its taste and texture. The secrets of the tomato, star of summer gardens, salads and gazpacho, is now laid out for plant breeders and horticulturists in exacting detail.
Adding to a growing list of plant gene maps, the Tomato Genome Consortium today published genome sequences for two tomatoes: The “Heinz 1706” varietal, an inbred cultivar that serves as a model for the domesticated tomato, and its closest wild counterpart, Solanum pimpinellifolium. The nine-year effort provides the closest glimpse yet of the 35,000 genes and 12 chromosomes of tomatoes, and by extension the rest of their extended plant family. The two sequences also tell the story of tomato domestication, notably its initial cultivation in the Americas and the introduction of “pomo d’oro” to the Old World in the 16th century.
The sequences provide new insight into the genes responsible for tomatoes’ characteristic color, flavor and texture, and could give plant biologists a wealth of new genetic information to manipulate, either through breeding or otherwise. Tomatoes represent a $2 billion market in the United States, according to Cornell.
“Tomato genetics underlies the potential for improved taste every home gardener knows and every supermarket shopper desires,” says James Giovannoni, a scientist at the Boyce Thompson Institute for Plant Research, located on the campus of Cornell University, who led the U.S. sequencing team. “The genome sequence will help solve this and many other issues in tomato production and quality.”
Just last week, plant biotechnologists cracked the code of tomato taste, using statistical analysis of taste tests to isolate two dozen flavor compounds controlling sweetness and intensity. “We now know exactly what we need to do to fix the broken tomato,” said Harry Klee of the University of Florida.
Today, that’s truer than ever. The two tomato gene sequences suggest there’s not much difference between delicious, sumptuously sweet garden varieties and the sandy-fleshed red blobs found at the supermarket. The varieties have just 0.6% nucleotide divergence, or 5.4 million single nucleotide polymorphisms, differentiating them - so breeding desirable qualities back into domesticated cultivars may not require many revisions.
As an example, around 50 genes are involved in the construction of tomato cell walls during fruit development, a trait which has a major impact on the fruit’s texture. The several million SNPs could have boundless potential, serving as a new reservoir of tomato traits.
Beyond just improving the tomato, the new genome sequences provide scientists with a new system for studying its closest relatives in the night-shade family. So many of our food crops are direct tomato relatives, including the potato, pepper, petunia, tobacco and even coffee. The Tomato Consortium obtained some data from the Potato Genome Sequencing Consortium and compared the two plants, which are genetically only 8 percent different. And other fleshy fruits could benefit, too - melons, apples, strawberries and many more share characteristics with tomatoes. A tomato gene framework will allow for easier comparison of common and divergent plant gene sequences.
It will also be much easier for other scientists - and seed companies and plant breeders - to sequence different tomato varietals, by building on this genome scaffold.
“Now we can start asking a lot more interesting questions about fruit biology, disease resistance, root development and nutritional qualities,” Giovannoni said in a statement.
(Source: http://www. popsci.com)
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TEXT
12. WHERE
ARE HENRY DAVID THOREAU'S PLANTS NOW?
It is astonishing how soon and unexpectedly flowers appear, when the fields are scarcely tinged with green. Yesterday, for instance, you observed only the radical leaves of some plants; to-day you pluck a flower. - Henry David Thoreau
In science as in anything else, history and tradition can be powerful teachers. So here’s a vivid lesson: Today, flowers and trees are awakening much earlier than they did 150 years ago, and there's proof in the journals of Henry David Thoreau.
Thoreau, best known for authoring “Walden,” was a prolific chronicler and admirer of nature. He kept detailed logs describing the first days when a plant or a tree flowered, which are now being used to document the changing face of Concord, Mass., as the earth grows warmer. Boston University botanist Richard Primack and National Park Service scientist Abe Miller-Rushing have spent a decade comparing Thoreau’s observations with their own.
“It was common at the time, particularly in Europe, for people to go around and write down when plants flowered, or when birds arrived, when frogs called,” said Miller-Rushing, Primack’s former grad student and now science coordinator for the Schoodic Education and Research Center at Maine’s Acadia National Park. “It was probably unusual to do it as diligently as Thoreau did, for 600-odd species of plants - that was not the norm.”
His journals offer an unparalleled phenological record - that is, a log of the timing of events, like a first flower or leaf growth. Looking back through Thoreau’s logs, as well as those of later botanists, Primack and Miller-Rushing found the first flowering date for 43 of the most common species has moved up by an average of 10 days.
Plants flower and grow leaves three our four days earlier for every 1 degree Celsius change in temperature, Primack said. As the temperature has changed by 2.5 C in Boston, that means plants are now flowering and leafing out one to two weeks earlier than they did in the past, depending on the species, he said. Those changes are related to sometimes drastic shifts in plant abundance - take for example the purple loosestrife, seen here.
Purple loosestrife is an invasive species in Concord, and it leafs out earlier in warm years, Primack said. Its expeditious blooming helps it beat native species for the most pollinators, and it is increasingly crowding them out. In other locations, temperature changes are drying wetlands, harming some native species and helping invaders.
“In Thoreau’s time, there were relatively few non-native, invasive species in Concord. But in the last 150 years, one of the most striking phenomena is the decline of large numbers of native wildflower species. Many species which used to be common in Concord, like the Canada lily, are very rare, and some species that weren’t present 150 years ago are extremely common,” Primack said.
Many plants’ growing seasons are also getting longer, Miller-Rushing said. This may have major impacts for pollinating insects, many of which have evolved to match the distinct flowering times of different species. These impacts are just beginning to be studied.
Miller-Rushing believes Thoreau’s records can make climate change real, in a way computer models or temperature predictions never could. “It’s one thing to say it is 3 degrees warmer now than it was however many years ago,” he said, “but it’s another thing to say that this plant, say blueberries, are flowering three weeks earlier than they used to.”
Thoreau himself probably said it best: “The question is not what you look at, but what you see.”
(Source: http://www. popsci.com)
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