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Source: American College of Gastroenterology
Date: October 15, 2007

Consumption Of Raw Fish Raises Potential Health Concerns For Consumers

Science Daily — Two case studies from Japan presented at the 72nd Annual Meeting of the American College of Gastroenterology point to a potential health problem in the United States, as more Americans consume raw fish in the form of sushi and sashimi. Anisakiasis (round worm) is a human parasitic infection caused by the consumption of raw or undercooked seafood containing Anisakis larvae.


Consumers should be aware that while larvae for the parasitic worm Anisakis cannot survive in a human host, the ingested larvae can produce severe intestinal problems warranting a visit to the emergency room.

When ingested by humans, the larvae attach themselves to the tissues lining the stomach and intestines, resulting in sudden abdominal pain, nausea, vomiting, and diarrhea. Since the larvae cannot survive in humans and eventually die, intestinal anisakiasis usually resolves on its own.

Researchers in Japan examined two cases of intestinal anisakiasis presenting as an obstruction of the small intestine. In each case, both patients, ages 64 and 70, were rushed to the emergency room with sudden abdominal pain and vomiting after eating raw sardines as sashimi two days earlier. The diagnosis of anisakiasis in the stomach can easily be confirmed by endoscopy.

However, small intestinal anisakiasis is difficult to diagnose. Both patients had abdominal X-rays showed air-fluid levels suggesting a small intestinal obstruction. Using a multidetector-row computed tomography (MDCT), doctors obtained high quality images of the small bowel, and found the intestinal blockage was caused by the presence of Anisakis larvae. Fluid replacement and resting immediately relieved the patients' symptoms.

Because the symptoms of anisakiasis can mimic other gastrointestinal diseases, it might potentially be misdiagnosed as appendicitis, acute abdomen (peritonitis) or stomach ulcers. According to Mashahiro Matshushita, MD of Haibara General Hospital, "Anisakiasis should be considered in the differential diagnosis of small intestinal obstruction."

Note: This story has been adapted from material provided by American College of Gastroenterology.

Source: University of Delaware
Date: October 15, 2007

Invasive Plant Secretes Acid To Kill Nearby Plants And Spread

Science Daily — Scientists at the University of Delaware have uncovered a hidden weapon that one of the most invasive wetland plants in the United States uses to silently and efficiently “bump off” its neighbors.



The invasive strain of Phragmites australis, or common reed, believed to have originated in Eurasia, exudes from its roots an acid so toxic that the substance literally disintegrates the structural protein in the roots of neighboring plants, thus toppling the competition.

“Phragmites is taking over the marsh world,” said UD plant biologist Harsh Bais. “It's a horticultural disaster.”

In Delaware alone, the tall, tasseled grass has overtaken tens of thousands of acres of wetlands, decreasing biodiversity, reducing the food and habitat available to wildlife, and altering wetland hydrology, transforming marshes once dissected by tidal creeks and open pools into much drier systems with dense monocultures of the plant.

Bais, who led the project, is an assistant professor of plant and soil sciences in UD's College of Agriculture and Natural Resources and holds an appointment at the Delaware Biotechnology Institute. His collaborators included postdoctoral researcher Thimmaraju Rudrappa, undergraduate student Justin Bonstall, and marine botanists John Gallagher and Denise Seliskar, who co-direct the Halophyte Biotechnology Center in UD's College of Marine and Earth Studies.

The results of the research are reported in the Journal of Chemical Ecology.

Bais is an expert on allelopathy, in which one plant produces a chemical to inhibit the growth of another plant. He refers to these plants with the capability to wage chemical warfare as “natural killers.”

Walnut trees, pine trees, ferns and sunflowers are among the plants that release harmful chemicals to prevent other plants from growing too close to them.

However, Phragmites uses this strategy not so much to keep other plants away, but to aggressively conquer them and invade new territory.

“We've seen this capability in a number of invasive plants that have come from Eurasia, such as garlic mustard,” Bais said. “The roots exude a toxin that kills native plants.”

In laboratory analyses at the Delaware Biotechnology Institute, Rudrappa and Bais used activated charcoal, the material in aquarium filters, to sequester secretions from both invasive and native Phragmites plants. The charcoal attracts and traps organic chemicals.

The scientists identified the toxin produced by Phragmites as 3,4,5-trihydroxybenzoic acid. Also known as gallic acid, it is used for tanning leather, to formulating astringents.

“It's nasty stuff,” Bais said. “If you get some of it on your skin, you definitely know it.”

The toxin works, Bais said, by targeting tubulin, the structural protein that helps plant roots to maintain their cellular integrity and grow straight in the soil. Within 10 minutes of exposure to the toxin in the lab, the tubulin of a marsh plant under siege starts to disintegrate. Within 20 minutes, the structural material is completely gone.

“When the roots collapse from the acid, the plant loses its integrity and dies,” Bais noted. “It's like having a building with no foundation--it's on its way to self-destruction.”

The native Phragmites also secretes the toxin, but the exotic strain releases much higher concentrations, which could be a key to its dominance, Bais said.

Today in Delaware, stands of native Phragmites are few and far between. Bais credits Gallagher and Seliskar, who have conducted extensive research on the plant, for growing sterile cultures of the native and exotic strains for his lab tests.

“This research reveals another weapon in the arsenal that Phragmites uses to overtake marshland,” Seliskar said.

“Screening large numbers of marsh plants to identify those that are naturally resistant to invasive Phragmites may be one avenue for preserving the native strain, as well as controlling the invasive's spread,” Bais noted.

With the current discovery in hand, Bais said he hopes to pursue further research to pinpoint exactly how the invasive Phragmites has become such a “super weed.” Such information could help scientists and environmental managers gain a foothold in halting Phragmites' rapid advance across the United States.

“We now know this plant secretes a toxin underground, but could it have a partner in crime?” Bais asks. “Could there be some kind of microbe, a deleterious pathogen, that is associated with this plant? And does this plant use changing environmental systems to its advantage? We just don't know the answers yet, but we'd like to find out.”

The research was sponsored by the Experimental Program to Stimulate Competitive Research (EPSCoR), a partnership of the National Science Foundation, the state of Delaware and Delaware's institutions of higher education. The program is managed by UD's Delaware Biotechnology Institute.

Note: This story has been adapted from material provided by University of Delaware.

ource: Carnegie Institution
Date: October 12, 2007

Green Algae: The Nexus Of Plant-Animal Ancestry

Science Daily — Genes of a tiny, single-celled green alga called Chlamydomonas reinhardtii may contain scores more data about the common ancestry of plants and animals than the richest paleontological dig. This work is described in an article in Science.


A group of researchers*, including Arthur Grossman of the Carnegie Institution, report on the results of a major effort to obtain the full library of genes, or the genome sequence, of Chamydomonas and to compare its ~15,000 genes to those of plants and animals, including humans. The research shows that this alga has maintained many genes that were lost during the evolution of land plants, has others that are associated with functions in humans, and has numerous genes of unknown function, but which are associated with critical metabolic processes.

"Although Chlamydomonas is certainly more plant than animal, there are clear similarities between this photosynthetic organism and animals that would surprise the average person on the street," comments Grossman. "Just twenty years ago no one would have guessed that an alga would have retained many of the functions we associate with humans and would be useful for developing a basic understanding of certain human diseases."

Chlamydomonas, affectionately called Chlamy, is an alga of 10 micrometres in size that is present in soil and freshwater environments. It performs photosynthesis like plants, but it diverged evolutionarily from flowering land plants about 1 billion years ago. It is even more distantly related to animals (the split between animals and plants was ~1.6 billion years ago). Chlamy moves using two anterior, hair-like flagella that were lost by its cousins, the flowering land plants, after the evolutionary split of the two lineages. The flagella are equivalent to the cilia and centrioles in animal cells. Centrioles are structures involved in cell division; they form a spindle apparatus, which helps separate genetic material into two new cells during mitosis. Cilia are important to many animal functions.

The study identified many new proteins that are likely associated with the flagella, and has distinguished those proteins of the flagella that are critical for movement and those that are associated with sensory functions (feeling the conditions in the environment). The analysis has also generated new insights about human diseases associated with ciliary dysfunction in humans, including those of the kidney and the eye.

The researchers also performed a comparative gene analysis across species to explore the evolutionary history of Chlamy, and the relationship of this alga to other organisms. Of the 6,968 protein families that have so-called homologs --proteins that have similar amino acid sequences, often reflecting a similar or related function among the species -- they found that Chlamy shared 35% (2,489/6,968) with both flowering plants and humans, and an additional 10% (706/6,968) with humans but not with flowering plants.

In addition, there are numerous proteins in Chlamy that make it suited to live in soil environments, including large families of specific transporters--proteins that help move material across cell membranes-- that enable it to scavenge nutrients from the soil. While some of these transporters have an affiliation with transporters in plants, others are more closely related to those in animals. Moreover, the Chlamy genome encodes many families of regulatory elements, including one that contains over 50 guanylyl/adenylyl cyclases-- enzymes probably involved in distinct developmental processes including mating and sexual signaling. There are also numerous genes and gene families that relate to making sugars and polysaccharides, to use the sugars and polysaccharides to produce energy and to build a highly structured and efficient chloroplast, the factory where the cell harnesses the energy of sunlight.

Indeed, many great insights from the genome analysis have come in the area of photosynthesis, the process of the chloroplast by which plants convert carbon dioxide, water and the energy of sunlight into oxygen and sugars. In a comparative genomic analysis, the scientists identified protein families that are shared by Chlamy, flowering plants, other algae, but are not present in nonphotosynthetic organisms. This exercise led them to identify photosynthesis-related proteins conserved across the plant kingdom, with many even conserved in the ancient cyanobacteria. (Cyanobacteria have been on the planet for ~3 billion years.) The majority of the identified proteins have unknown functions, but are probably critical since they have been exclusively maintained in photosynthetic organisms over nearly the entire period that life has inhabited the Earth.

As Grossman states, "The work has generated a clear roadmap for exploring the roles of numerous genes in photosynthetic function, for defining the structure and dynamic aspects of flagellar function and for understanding how the soil environment, with its large fluctuations in nutrients, has molded the functionality of organisms through evolutionary time."

Source: US Department of Agriculture
Date: October 14, 2007

Switchgrass: Bridging Bioenergy And Conservation

Science Daily — An important part of the answer to the country's energy woes could be blowing in the prairie wind, according to Agricultural Research Service (ARS) plant geneticist Michael Casler. He has spent the past 10 years breeding switchgrass, an eight-foot-plus native plant that was an integral part of the tall grass prairies that once dominated America's Midwest.


As a breeder, Casler is mostly concerned with the plant's bioenergy-friendly attributes, including its ability to accumulate large amounts of biomass and tolerate environmental stress. Casler works at the agency's U.S. Dairy Forage Research Center in Madison, Wis.

Recently, he began looking at switchgrass from another standpoint—as a restorer of once-pristine prairies. Historically, a sprawling seas of grasses once stretched from Montana and the Dakotas down to Texas, with pockets of prairie as far east as New York. Now, with much of this land fragmented or altered, only a patchwork of remnant prairies remains.

Numerous federal, state and private conservation efforts are examining how best to revive these vestigial prairies. But a question of genealogy always arises: Which switchgrass varieties should be planted that will be in keeping with a site's genetic legacy?

Some conservationists insist on using only long-established, local varieties of switchgrass. Others argue that modern-day cultivars can appropriately be used.

Along with ARS scientist Kenneth Vogel in Lincoln, Neb., Casler set out to bring clarity to this debate and, hopefully, ease the task of grassland restoration.

After two summers spent trekking native Midwestern prairies, plucking samples and sending them back to his laboratory, Casler discovered that today's agronomically important switchgrass cultivars are nearly identical genetically to their grassy ancestors.

The study's findings are good news for prairie restorers, who can confidently tap a wider pool of switchgrass cultivars and local varieties for conservation projects. And switchgrass growers can take satisfaction knowing their fields still are, in many ways, symbolic of the country's rich grassy past.

Note: This story has been adapted from material provided by US Department of Agriculture.

Source: Oxford University
Date: October 10, 2007

Tiny Crow Camera Spies On Clever Birds

Science Daily — A new technique developed by Oxford University
Bird Control


The scientists developed miniaturised video cameras with integrated radio-tags that can be carried by wild, free-flying birds. Using this new ‘video-tracking’ technology, they spied on the behaviour of New Caledonian crows, a species renowned for its sophisticated use of tools, recording behaviours never seen before.

Observing New Caledonian crows in the wild is extremely difficult because they are easily disturbed and live in densely forested, mountainous terrain. ‘Video-tracking’ enabled the Oxford scientists to obtain particularly intimate observations of crow behaviour.

‘Everyone thought that New Caledonian crows use tools mainly to probe into holes and cracks in rotting wood and tree crowns, but we now discovered that they use tools even on the ground,’ said Dr Christian Rutz, from the Behavioural Ecology Research Group at Oxford’s Department of Zoology.

One crow was seen probing leaf litter with grass-like stems – a mode of tool use, and a tool material, that decades of observation with conventional techniques had missed. ‘This discovery highlights the power of our new video-tracking technology’ said Dr Rutz, who leads the group’s field research. ‘This is the first time that wild birds have been tracked in this way, and it has already changed our understanding of New Caledonian crow behaviour.’

For the study, 18 crows were fitted with ‘tailcams’ with each unit weighing about 14 grams – only slightly heavier than a conventional radio-tag. The units were attached to two tail feathers with strips of adhesive tape, and were designed so that they did not adversely affect the bird’s movements, and could be removed by the crows themselves or would detach after a few weeks with the birds’ natural moulting process.

‘Observing wild birds this closely in their natural habitat has been one of the final frontiers of ornithological field research,’ said Dr Rutz. ‘Whilst video footage has been taken before using tame, trained birds, it is only now that we have been able to design cameras that are small and light enough to travel with wild birds and let them behave naturally. Potentially, this new video technology could help us to answer some long-standing questions about the ecology and behaviour of many other bird species that are otherwise difficult to study.’

A report of the research, entitled ‘Video Cameras on Wild Birds’ was published in Science Express on Thursday 4 October 2007. The research was undertaken by Dr Christian Rutz, Lucas Bluff, Dr Alex Weir and Professor Alex Kacelnik from the Behavioural Ecology Research Group at the Department of Zoology and was funded by the Biotechnology and Biological Sciences Research Council (BBSRC).

Note: This story has been adapted from material provided by Oxford University.