February 12, 2009, 6:25 AM CT

Seamounts may serve as refuges for deep-sea animals

Over the last two decades, marine biologists have discovered lush forests of deep-sea corals and sponges growing on seamounts (underwater mountains) offshore of the California coast. It has generally been assumed that a number of of these animals live only on seamounts, and are found nowhere else. However, two new research papers show that most seamount animals can also be found in other deep-sea areas. Seamounts, however, do support especially large, dense clusters of these animals. These findings may help coastal managers protect seamounts from damage by human activities.

Tens of thousands of seamounts dot the world's ocean basins. Eventhough some shallower seamounts have been used as fishing grounds, few seamounts have been studied in detail. Davidson Seamount, about 120 kilometers (75 miles) offshore of the Big Sur coast, is an exception. Since 2000, scientists have spent over 200 hours exploring its slopes and peaks using the remotely operated vehicle (ROV) Tiburon.

Two of the expeditions to Davidson Seamount were led by Andrew DeVogelaere of the Monterey Bay National Marine Sanctuary and were funded by the National Oceanic and Atmospheric Administration's Office of Exploration. Other expeditions were funded by the David and Lucile Packard Foundation (through MBARI) and were led by MBARI biologist James Barry, who studies seafloor animals, and by geologist David Clague, who studies undersea volcanoes......... Posted by: Kelly      Read more         Source

February 11, 2009, 6:21 AM CT

Why those fruits ripen and flowers die

Best known for its effects on fruit ripening and flower fading, the gaseous plant hormone ethylene shortens the shelf life of a number of fruits and plants by putting their physiology on fast-forward. In recent years, researchers learned a lot about the different components that transmit ethylene signals inside cells. But a central regulator of ethylene responses, a protein known as EIN2, resisted all their efforts.

Finally, after more than a decade of constant probing, a team of scientists led by Joseph Ecker, Ph.D., a professor in the Plant Biology laboratory and director of the Salk Institute Genomic Analysis Laboratory, successfully pinned down the elusive protein. Turns out, the presence of ethylene stabilizes the otherwise ephemeral EIN2 allowing it to gather up enough strength to pass on ethylene's message.

Their findings, reported in the Feb. 15, 2009 edition of the journal Genes and Development, are an important step toward defining EIN2's role in growth and development and modifying key processes to improve agriculture, preventing crop losses due to ethylene related processes.

"Ethylene is involved in a wide variety of processes and we knew from genetic experiments that EIN2 is right at the center of ethylene signaling pathway, but for the longest time we were unable to figure out how it is regulated," says Ecker. "Now that we know that EIN2 is negatively regulated by protein degradation, we can begin to understand how it triggers all these different ethylene responses in plants"......... Posted by: Erica      Read more         Source

February 11, 2009, 6:03 AM CT

Stopping the spread of rice virus

Building on plant virus research started more than 20 years ago, a biologist at Washington University in St. Louis and his colleague at the Donald Danforth Plant Science Center in St. Louis have discovered a technology that reduces infection by the virus that causes Rice Tungro Disease, a serious limiting factor for rice production in Asia.

Roger N. Beachy, Ph.D., WUSTL professor of biology in Arts & Sciences and president of the Donald Danforth Plant Science Center, and Danforth Center research scientist Shunhong Dai, Ph.D., demonstrated that transgenic rice plants that overexpress either of two rice proteins are tolerant to infection caused by the rice tungro bacilliform virus (RTVB), which is largely responsible for the symptoms linked to Rice Tungro disease.

The two proteins, RF2a and RF2b, were discovered in Beachy's lab several years ago and are transcription factors known to be important for plant development; the new data suggest that they appears to be involved in regulating defense mechanisms that protect against virus infection. The discovery, reported in the December 22, 2008, issue of the Proceedings of the National Academy of Sciences, may open new avenues in the search for disease resistance genes and pathways in plants and other organisms.

Plant viral diseases cause serious economic losses in agriculture, second only to those caused by fungal diseases. Rice Tungro disease is prevalent primarily in south and southeast Asia and accounts for nearly $1.5 billion annual loss in rice production worldwide. Preventing the occurrence and spread of this virus could result in increased yields ranging from five to 10 percent annually in affected areas......... Posted by: Erica      Read more         Source

February 10, 2009, 6:25 AM CT

No joy in discoveries of new mammal species

In the era of global warming, when a number of researchers say we are experiencing a human-caused mass extinction to rival the one that killed off the dinosaurs, one might believe that the discovery of a host of new species would be cause for joy. Not entirely so, says Paul Ehrlich, co-author of an analysis of the 408 new mammalian species discovered since 1993.

"What this paper really talks about is how little we actually know about our natural capital and how little we know about the services that flow from it," said Paul Ehrlich, the Bing Professor of Population Studies at Stanford.

"I think what most people miss is that the human economy is a wholly owned subsidiary of the economy of nature, which supplies us from our natural capital a steady flow of income that we can't do without," Ehrlich said. "And that income is in the form of what are called 'ecosystem services'-keeping carbon dioxide out of the atmosphere, supplying fresh water, preventing floods, protecting our crops from pests and pollinating a number of of them, recycling the nutrients that are essential to agriculture and forestry, and on and on".

Ehrlich conducted the analysis with Gerardo Ceballos, a professor of biology at the National University of Mexico. They are co-authors of a paper describing the work, scheduled to be published Monday, Feb. 9, in the online early edition of the Proceedings of the National Academy of Sciences........ Posted by: Kelly      Read more         Source

February 10, 2009, 6:23 AM CT

Salamander decline in Central America

The decline of amphibian populations worldwide has been documented primarily in frogs, but salamander populations also appear to have plummeted, as per a newly released study by University of California, Berkeley, biologists.

By comparing tropical salamander populations in Central America today with results of surveys conducted between 1969 and 1978, UC Berkeley scientists have observed that populations of a number of of the commonest salamanders have steeply declined.

On the flanks of the Tajumulco volcano on the west coast of Guatemala, for example, two of the three commonest species 40 years ago have disappeared, while the third was nearly impossible to find.

"There have been hints before people went places and couldn't find salamanders. But this is the first time we've really had, with a very solid, large database, this kind of evidence," said study leader David Wake, professor of integrative biology at UC Berkeley and curator of herpetology in the campus's Museum of Vertebrate Zoology.

Frog declines have been attributed to a variety of causes, ranging from habitat destruction, pesticide use and introduced fish predators to the Chytrid fungus, which causes an often fatal disease, chytridiomycosis.

These do not appear to be responsible for the decline of Central American salamanders, Wake said. Instead, because the missing salamanders tend to be those living in narrow altitude bands, Wake believes that global warming is pushing these salamanders to higher and less hospitable elevations......... Posted by: Kelly      Read more         Source

February 10, 2009, 6:11 AM CT

How an Antarctic worm makes antifreeze

Two BYU scientists who just returned from Antarctica are reporting a hardy worm that withstands its cold climate by cranking out antifreeze. And when its notoriously dry home runs out of water, it just dries itself out and goes into suspended animation until liquid water brings it back to life.

Identifying the genes the worm uses to kick in its antifreeze system can be useful information - similar genes found in other Antarctic organisms are currently being used to engineer frost-resistant crops.

But BYU's Byron Adams, associate professor of molecular biology, and his Ph.D. student Bishwo Adhikari, are carrying on their love affair with microscopic nematode worms for a different reason.

They spent Christmas near the South Pole to help determine how the fate of a half-millimeter worm can actually impact an entire ecosystem, and how that information can serve as an important baseline for understanding climate change's impact on more complex systems, such as a farmer's field in the United States.

Their latest study, published Monday in the journal BMC Genomics, used samples Adams gathered during prior trips to the world's most inhospitable continent. He's lived at McMurdo Station seven times and hitched helicopter rides to gather soil from Antarctica's freezing, bone-dry valleys, where only a handful of microscopic animals can survive. The ones that do make for a convenient laboratory for observing how minor changes in the environment can have a big impact on an ecosystem......... Posted by: Kelly      Read more         Source

February 9, 2009, 6:22 AM CT

Scientists deconstruct cell division

The last step of the cell cycle is the brief but spectacularly dynamic and complicated mitosis phase, which leads to the duplication of one mother cell into two daughter cells. In mitosis, the chromosomes condense and the nucleus breaks down. Fibrous structures called spindles form, which then move the chromosomal material toward opposite ends of a cell and help partition other cell contents. If something goes wrong, diseases such as cancer can arise. Researchers have tried for years to unravel the process of spindle assembly. Now, scientists at Carnegie's Department of Embryology have observed that two proteins dynein and Nudelinvolved in other cell-division functions, are essential to regulate assembly of the spindle matrix.

"The mechanisms that cells use during division to partition both chromosomes and regulatory factors into their daughters are widely recognized as among the most fundamental processes in all of biology. During the last several years no one has done more than Yixian Zheng to broaden our understanding of how dividing cells control these critical events," said Allan Spradling, Department of Embryology director.

"To ensure proper cell division, the mother cell needs to separate its genetic materials, the chromosomes, equally, but also partition its cellular content properly into daughter cells," explained co-author Yixan Zheng. "Cell division allows a fertilized egg to develop into multicellular organisms with different types of cells. It also replenishes adult tissues, such as skin and bones. Forming a spindle requires the assembly of a 'skeleton' from tube-like microtubules and the construction of a poorly defined scaffold called a spindle matrix"......... Posted by: Janet      Read more         Source

February 6, 2009, 6:07 AM CT

Silencing of jumping genes in pollen

Researchers at the Instituto Gulbenkian de Cincia (IGC), in Portugal, are to date the only research group in the world capable of isolating the sperm cells in the pollen grain of the model plant Arabidopsis thaliana This technique was crucial in a study to be reported in the latest issue of the journal Cell, which describes how mobile sequences of DNA (called transposable elements) are silenced in the sperm cells, thus ensuring suppression of the mutagenic effects of these DNA elements.

Jrg Becker, Jos Feij and their team, at the IGC, and Robert Martienssen and his colleagues, at the Cold Spring Harbor Laboratory, CSHL,in the USA, have unveiled a mechanism for controlling transposable elements that may be extensible to other eukaryotes, such as the fruit fly, amoebae and algae.

Transposable elements are very common in all known genomes. In the human genome, for example, they make up 45% of the total genome. They are involved in the evolution of genomes, since when integrated back into the genome they can affect the function and organisation of other genes. However, transposable elements are mutagens, and, therefore, their activation needs to be under tight control, as it appears to be harmful to the cell and the organism. If such harmful mutations occur in sexual cells, they will be transmitted to the progeny and spread in the population......... Posted by: Erica      Read more         Source

February 4, 2009, 11:12 PM CT

Bacteria Jump From Host to Host

All life - plants, animals, people - depends on peaceful coexistence with a swarm of microbial life that performs vital services from helping to convert food to energy to protection from disease.

Now, with the help of a squid that uses a luminescent bacterium to create a predator-fooling light organ and a fish that uses a different strain of the same species of bacteria like a flashlight to illuminate the dark nooks of the reefs where it lives, researchers have observed that gaining a single gene is enough for the microbe to switch host animals.

The finding, reported this week (Feb. 1) in the journal Nature by a team of researchers from UW-Madison, is important not only because it peels back some of the mystery of how bacteria evolved to colonize different animals, but also because it reveals a genetic pressure point that could be manipulated to thwart the germs that make us sick.

"It seems that every animal we know about has microbes linked to it," says Mark J. Mandel, the main author of the study and a postdoctoral fellow in the UW-Madison School of Medicine and Public Health. "We pick up our microbial partners from the environment and they provide us with a raft of services from helping digestion to protection from disease".

In the Pacific, a species of bacteria known as Vibrio fischeri lives in luminescent harmony with two distinct hosts: the diminutive nocturnal bobtail squid and the reef-dwelling pinecone fish. In the squid, which feeds at night near the ocean surface, one strain of the bacterium forms a light organ that mimics moonlight and acts like a cloaking device to shield the squid from hungry predators below. In the pinecone fish, another strain of the bacterium colonizes a light organ within the animal's jaw and helps illuminate the dark reefs in which it forages at night. The fish light organ may also play a role in attracting the zooplankton that make up the pinecone fish's menu......... Posted by: Kelly      Read more         Source

February 4, 2009, 11:09 PM CT

Why Don't More Animals Change Their Sex

Most animals, like humans, have separate sexes - they are born, live out their lives and reproduce as one sex or the other. However, some animals live as one sex in part of their lifetime and then switch to the other sex, a phenomenon called sequential hermaphroditism. What remains a puzzle, as per Yale scientists, is why the phenomenon is so rare, since their analysis shows the biological "costs" of changing sexes rarely outweigh the advantages.

A report by Yale researchers in the recent issue of The American Naturalist says that while this process is evolutionarily favored, its rarity cannot be explained by an analysis of the biological costs vs benefits.

Sequential hermaphroditism naturally occurs in various organisms from plants to fishes. Following four decades of research that established why sex change is advantageous, the question remained why it is rare among animals. In this study, Yale graduate student Erem Kazancioglu and his advisor Suzanne Alonzo, assistant professor of ecology and evolutionary biology, demonstrate that sex change is surprisingly robust against costs.

While the adaptive advantage of sex change is well understood, it is not clear why relatively few animals change sex. As per Alonzo, "An intuitive, yet rarely studied, explanation is that the considerable time or energy it takes to change sex make hermaphroditism unfeasible for most animals"......... Posted by: Kelly      Read more         Source