March 6, 2006, 11:39 PM CT

The Way To A Bigger Brain

Hatchery-reared steelhead trout show increased growth of some parts of the brain when small stones are scattered on the bottom of their tank, according to a new study by researchers at UC Davis. The brains of those young fish were closer to those of salmon reared in the wild, and the fish also showed behavior closer to wild than to hatchery-reared fish.

"There's an obvious difference between the hatchery and the wild fish," said graduate student Rebecca Kihslinger, who carried out the study with Gabrielle Nevitt, professor of neurobiology, physiology and behavior at UC Davis. "A simple change affected brain growth in a large-scale way".

The results could affect the design of hatcheries for breeding fish to restock wild populations, Kihslinger said. The study is published in the February 2006 issue of the Journal of Experimental Biology.

Wild steelhead lay their eggs in gravel nests on the riverbed. After hatching, the fry, called alevins, stay among the gravel and live off their yolk sac until they emerge as free-swimming fry. In hatcheries, the fish are reared in tanks of clean, well-aerated water, but without environmental features or enrichment.

Earlier work by Nevitt's lab at UC Davis and other labs has shown differences between hatchery-reared and wild fish, Kihslinger said. But most studies have looked at older fish, and have not distinguished between the effects of selective breeding for "domesticated" fish and of the environment in which the fish live.........

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March 4, 2006, 9:49 PM CT

For Bands of Marching Crickets

Group living has its price. At least that's the case for the millions of Mormon crickets that trekked together across the grasslands of southern Idaho last summer.

In observing this massive march, Agricultural Research Service (ARS) ecologist Gregory Sword and his colleagues discovered that while the insects' banding together shielded them from predatory birds and mammals, food deprivation brought on by a competition for certain nutrients led the crickets to cannibalism.

Scientists have long wondered what drives some insects, such as North America's Mormon cricket and Africa's desert locust, to move en masse. The team's finding-that movement is propelled by the nutrient-starved insects themselves, literally nipping at each others' heels out of hunger and out of fear of being eaten-is a completely novel explanation.

In the western United States, Mormon crickets can form up to six-mile-long bands, puzzling residents and pilfering crops and garden plants as they move across the landscape.

To better understand these bewildering and sometimes devastating swarms, Sword-who recently accepted a position with the University of Sydney in Australia-joined fellow scientists Stephen Simpson of the University of Sydney, Patrick Lorch of Kent State University in Ohio and Iain Couzin of the University of Oxford in the UK.........

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March 3, 2006, 7:05 AM CT

Mass Migration Of Mormon Crickets Driven By Hunger And Fear

An international team of researchers, including Kent State University professor Dr. Patrick D. Lorch, have revealed the motivating factors behind the seasonal mass migration of Mormon crickets in western North America.

The researchers report hunger for protein and salt, and a fear of cannibalism, drives the mass migration of Mormon crickets in western North America.

Throughout their seasonal migration, millions of Mormon crickets (relatives of locusts and grasshoppers) cover more than 50 miles of ground, destroying farmland and causing hazardous driving conditions along the way.

The research team, led by Dr. Stephen J. Simpson, conducted field observations and experimentation to determine that two driving forces are behind the migration: a need for protein and a fear of cannibalism.

Their results reveal a different model for collective motion, with the crickets' migration in effect a forced march. The constant threat of cannibalism from the rear appears to push the crickets' movement as much as the need to find protein and salt pulls it, scientists say.

The team's findings could lead to more environmentally friendly tactics for controlling large swarms of insects.........

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March 2, 2006, 8:37 PM CT
A better look at viruses through code
New software developed by Purdue University’s Wen Jiang enables scientists to observe viruses at an unprecedented level of detail. “While before we could only see virus parts that were symmetric, we can now see those that have non-symmetric structures, such as portions of the one our paper focuses on, the Epsilon 15 virus that attacks salmonella......

New software developed by Purdue University’s Wen Jiang enables scientists to observe viruses at an unprecedented level of detail.

“While before we could only see virus parts that were symmetric, we can now see those that have non-symmetric structures, such as portions of the one our paper focuses on, the Epsilon 15 virus that attacks salmonella. . .This software will enable a substantial expansion of what we can see and study. We remain limited to observing those viruses that are identical from one individual viral particle to the next - which, sadly, is still only a small portion of the viral species that are out there. But it is a major step forward toward our goal of seeing them all.”

[press release]

via Medgadget

Source

February 28, 2006, 11:48 PM CT

Art in Crystallography

This watercolor illustration, entitled Blood 2,000,000X, shows a cross-section through the blood, magnified by about two million times. It received first place in a new competition, called Art in Crystallography, sponsored by the American Crystallographic Association (ACA) Newsletter and the ACA Council. It was created by David Goodsell, an artist and crystallographer at the Scripps Research Institute in California.

Blood serum, the clear fluid part of the blood, is shown in the upper half and a red blood cell in the lower half. In the serum, look for Y-shaped antibodies, long thin molecules of fibrinogen (a protein that helps perform coagulation, in light red) and a number of small albumin proteins (the most common types of proteins in the blood). The large UFO-shaped objects are low density lipoprotein (the "bad" type of cholesterol) and the six-armed protein is complement C1, a protein involved in defense against bacterial infection. The red blood cell is filled with hemoglobin, in red.The cell wall, in purple, is braced on the inner surface by a network of structural proteins, with long chains of spectrin connected together by small segments of actin. (Source: ACA's Art in Crystallography website.).

Source: American Institute of Physics........

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February 27, 2006, 8:01 PM CT

Life Leaves Subtle Signature

Mars looks more like Earth the more we see of the red planet's surface, but there's one big difference: complex life forms have existed on Earth for billions of years.

"The meandering stream channels, deltas and alluvial fans of Mars are all familiar to us here," said William Dietrich, a geologist at the University of California at Berkeley. "But we're looking at Mars from a distance. Up close and personal, the view of Earth is a very different one.

"Can we tell from topography alone that life pervades Earth?" wondered Dietrich and colleagues.

They found, to their surprise, no overt signature of life in Earth's landforms, but a more muted signature does exist. The main topographical difference between an Earth teeming with life and one with no life, Dietrich concludes, is that life likely creates more of the rounded hills typical of Earth's vegetated areas, and fewer sharp, rocky ridges.

"It turns out that life creates a more subtle effect on the land," said Richard Lane, program director in the National Science Foundation's (NSF) Division of Earth Sciences. "The absence of life likely would lead to a planet with sharp hill slopes of exposed bedrock, which is not what Earth looks like".

Everywhere you look, "life is causing sediment to move downhill," Dietrich said. "Tree roots, gophers and wombats all dig into the soil and raise it, tearing up the underlying bedrock and turning it into rubble that tumbles downhill and leaves behind more rolling hills".........

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February 23, 2006, 11:43 PM CT

El Nino Events Affect Whale Breeding

New research shows that global climate processes are affecting southern right whales (Eubalaena australis) in the South Atlantic. A thirty-year study by an international team of researchers found a strong relationship between breeding success of whales in the South Atlantic and El Nino in the western Pacific. The results are published this week in the On-line journal Biology Letters.

Southern right whales migrate from the South Atlantic to the Southern Ocean to feed. Researchers know from other studies that following El Nino, changes in sea temperatures affect the availability of krill, a shrimp-like crustacean, which is the main diet of these whales. It is known that these changes affect penguins and seals in the Antarctic, but this is the first time the link has been made with whales as they return to their calving grounds in the South Atlantic.

Keith Reid from British Antarctic Survey (BAS) said, "These results help us to understand processes in three connected oceans and are crucial to predicting the consequences of climate change on the whales."

Southern right whales have been internationally protected since 1935. Their populations are showing signs of recovery, however, sea surface temperatures in parts of the Southern Ocean have increased by 1 degree C over the last 50 years and if they continue to rise this could threaten their recovery.........

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February 22, 2006, 10:47 PM CT

Ancient Origin Of Vertebrate Skeleton

University of Florida researchers have found that people have an ancient skeleton in their closets - a skeleton personified today by a jawless, eel-like fish.

It turns out lampreys, long thought to have taken a different evolutionary road than almost all other backboned animals, may not be so different after all, particularly in terms of the genetics that govern their skeletal development, as per findings would be published online this week in the Proceedings of the National Academy of Sciences.

UF researchers found the same essential protein that builds cartilage in this odd animal - it spends the first five years of its development in the larval stage before it finally morphs into a boneless fish - is none other than collagen. This vital structural molecule is found in all vertebrates with backbones and jaws, including humans.

"It was thought collagen was a relatively recent invention in vertebrate evolution that unites us with reptiles, amphibians, sharks and bony fishes, while the lamprey skeleton was based on quite different proteins," said Martin Cohn, Ph.D., a developmental biologist and associate professor with the UF departments of zoology and anatomy and cell biology. "Knowing that lampreys also use collagen to build their skeletons makes sense. Lampreys and jawed vertebrates inherited the same genetic program for skeletal development from our common ancestor."........

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February 21, 2006, 9:03 PM CT

Monitoring Baleen Whales

Like robots of the deep, autonomous underwater vehicles, or AUVs, are growing in number and use in the oceans to perform scientific missions ranging from monitoring climate change to mapping the deep sea floor and surveying ancient shipwrecks. Another use for these versatile platforms has now been found: monitoring the lives of whales.

Marine mammals are major predators in the ocean, but little is known about many of them and how changing ocean conditions affect their distribution. Traditional ship or aerial surveys rely on human observers to detect marine mammals, but these observations are limited to daylight hours and periods of calm seas and good visibility. As a result, these surveys are time-consuming, inefficient, and expensive. Marine mammals can also be detected by passively listening for their vocalizations. Passive acoustic monitoring of marine mammals is unaffected by weather, but most applications to date have involved moored or fixed recorders that can assess only when marine mammals appear in a single location.

Scientists at the Woods Hole Oceanographic Institution (WHOI) have reported the first use of passive acoustic recorders in an ocean glider, a type of AUV that looks like a large model airplane and can work in water depths to 1,000 meters (about 3,300 feet) or more.........

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February 20, 2006, 10:20 PM CT

Listening for the Fish

Rosenstiel School fisheries scientists will embark on state-of-the-art research at the end of February to track black and red grouper in the Dry Tortugas National Park to develop a better understanding of species' movement and habitat require-ments, so they can help more efficiently design and assess future marine-protected areas. Through funding from the National Park Service and transportation support from Yankee Fleet Ferry Service, researchers will be able to conduct this high-tech observation that involves surgically implanted transmitters for approximately a year.

The researchers have designed a field study that uses acoustic telemetry technology to track continuously the movements and habitat use of red and black grouper in the Dry Tortugas National Park, the 46-square-nautical-mile marine reserve. The groupers will be fitted with transmitters or "pingers" that emit unique acoustic codes underwater approximately every 20 seconds. Passive listening stations or receivers will be placed in a submersed array that can detect the transmitters. Receivers will record an acoustic tag's presence when it is within range, commonly 250-1,000 meters, depending on the oceanographic conditions. And, because the tags each emit unique identification numbers and time stamps, individual receivers could potentially detect up to 4,000 different fish at any given time.........

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