August 26, 2010, 11:16 PM CT

Ants use multiple antibiotics as weed killers

Research led by Dr Matt Hutchings and published recently in the journal BMC Biology shows that ants use the antibiotics to inhibit the growth of unwanted fungi and bacteria in their fungus cultures which they use to feed their larvae and queen.

These antibiotics are produced by actinomycete bacteria that live on the ants in a mutual symbiosis.

Eventhough these ants have been studied for more than 100 years this is the first demonstration that a single ant colony uses multiple antibiotics and is reminiscent of the use of multidrug treatment to treat infections in humans.

The work, which was funded by the UK Medical Research Council, has also identified a new antibiotic that could be used to treat fungal infections.

Fungiculture in the insect world is practiced by ants, termites, beetles and gall midges.

Dr Hutchings' research investigates the Acromyrmex octospinosus leaf cutter ant, endemic in South and Central America and the southern US. These ants form the largest and most complex animal societies on earth with colonies of up to several million individuals. The garden worker ants researched were collected from three colonies in Trinidad and Tobago.

Dr Hutchings said: "This was really a fun project which started with a PhD student, Joerg Barke, streaking leaf-cutting ants onto agar plates to isolate antibiotic producing bacteria. Joerg, with his colleagues Ryan Seipke and Sabine Gruschow, really pushed this project forwards and made these major discoveries. They really deserve most of the credit for this work"......... Posted by: Kelly      Read more         Source

August 26, 2010, 11:06 PM CT

Genome Comparison of Ants

By comparing two species of ants, Shelley Berger, PhD, the Daniel S. Och University Professor at the University of Pennsylvania, and his colleagues Danny Reinberg, PhD, New York University, and Juergen Liebig, PhD, Arizona State University, have established an important new avenue of research for epigenetics -- the study of how the expression or suppression of particular genes affects an organism's characteristics, development, and even behavior.

Ants, the new model system used in this study, organize themselves into caste-based societies in which most of the individuals are sterile females, limited to highly specialized roles such as workers and soldiers. Only one queen and the relatively small contingent of male ants are fertile and able to reproduce. Yet despite such extreme differences in behavior and physical form, all females within the colony appear to be genetically identical.

Berger, who directs Penn's Epigenetics program, and his colleagues think that epigenetic mechanisms - chemical modifications to DNA and its supporting proteins that affect gene expression - appears to be critical in establishing such broad variations in behavior and morphology that arise in individuals, despite having the same genome.

As per a research findings published in Science this week, Berger, her Penn colleagues, and a diverse international team of collaborators including ant biologists, geneticists, and biochemists from Arizona State, NYU, Howard Hughes Medical Institute, and the Chinese Academy of Sciences, showed how differences in gene expression between two ant species, the Florida carpenter ant (Camponotus floridanus) and Jerdon's jumping ant (Harpegnathos saltator), correlate with separate castes in each......... Posted by: Kelly      Read more         Source

August 25, 2010, 7:08 AM CT

Make Way for Ducklings

Parent birds know best when it comes to taking care of their babies. But, when food gets scarce and they are forced to fly longer distances to grab a bite, "egg sitting" time drops off. What impact does this have on their brood?

"I guess everybody, from a human health perspective, knows that what a mother does during pregnancy can have all sorts of effects on her babies," says Bill Hopkins, an associate professor in the Department of Fisheries and Wildlife Sciences at Virginia Tech. He is holding a duckling in his hand. It's one of a number of he and his team are studying. "We study how these little guys can be affected by the things that mom does".

A member of his research team, Sarah DuRant, examines an egg. "If you look really closely," she says, "you can see the embryo moving".

With the support of the National Science Foundation (NSF), ecologists Hopkins and DuRant are studying wood ducks to better understand the impact of mom's nesting behavior on her ducklings and their ability to survive.

"How much time a female spends on her nest is going to influence the temperature that the nest is at," notes DuRant. The scientists incubate eggs at different temperatures to simulate warmer and cooler nesting conditions. "What we're interested in are very, very subtle changes in temperature, maybe a degree Celsius at most," adds Hopkins......... Posted by: Kelly      Read more         Source

August 25, 2010, 7:06 AM CT

Glue That Holds Oyster

Oyster reefs are on the decline, with over-harvesting and pollution reducing some stocks as much as 98 percent over the last two centuries.

With a growing awareness of oysters' critical roles filtering water, preventing erosion, guarding coasts from storm damage, and providing habitat for other organisms, scientists have been investigating how oyster reefs form in order to better understand the organisms and offer potential guidance to oyster re-introduction projects.

At the same time, scientists have been studying marine animals' various adhesives, uncovering fundamental properties that could yield new innovations from replacements for medical sutures to surface coatings that keep waterborne craft from picking up marine hitchhikers.

Now, scientists from Purdue University and the University of South Carolina have shown that oysters produce a unique adhesive material for affixing themselves to each other, a cement that differs from the glues used by other marine organisms.

The scientists are presenting their findings at the 2010 Annual Meeting of the American Chemical Society in Boston, Mass., on Aug. 24, and will publish their results in the Sept. 15, 2010, issue of the Journal of the American Chemical Society. (The article is available online now.)......... Posted by: Kelly      Read more         Source

August 10, 2010, 6:33 AM CT

Fluorescence Shed New Light

A lot has changed about the way researchers study sexual selection and reproduction. Some of it has to do with new tools; some of it has to do with new attitudes. There is a lot more going on than just "sperm meets egg".

"It was simply thought of as "this army of sperm competing," so it functioned as a raffle; the more tickets you bought, the more sperm you transferred, the more likely you were to win out in that competition," explains Scott Pitnick, a professor of biology at Syracuse University. "Females were perceived as these passive vessels in which this competition played out--that females didn't play an active role. That's really not the case."

With help from the National Science Foundation (NSF), Pitnick studies reproduction and sexual selection in fruit flies.

"A sea change came in the mid-'90s in earnest when people started paying attention to the female side of things, and sperm-female interactions, and it turns out that's really where all the action is," he continues. "There has been a real male bias in this field, as in most fields of science. And now, in the sperm competition field, there are as a number of female as male [scientists], and it really has changed the focus considerably and in a very positive way".

For example, modern DNA technology that can confirm paternity opened scientists' eyes to the reality that monogamy is more the exception than the rule in most species......... Posted by: Kelly      Read more         Source

July 23, 2010, 6:50 AM CT

Ancient "stress hormone" in pre-historic fish

A University of British Columbia zoologist has discovered a new corticosteroid hormone in the sea lamprey, an eel-like fish and one of the earliest vertebrates dating back 500 million years. These findings have shed light on the evolution of steroid hormones and may help conservation and management efforts for lampreys.

"This new discovery has significant scientific implications and application for lamprey conservation," says principal investigator and main author David Close, an assistant professor in the UBC Department of Zoology and director of the Aboriginal Fisheries Research Unit at UBC's Fisheries Centre.

Close and his colleagues at Michigan State University identified a corticosteroid hormone - called 11-deoxycortisol - in the sea lamprey that plays dual roles in balancing ions and regulating stresses, similar to aldosterone and cortisol in humans. The findings are published online this week in the Proceedings of National Academy of Sciences Early Edition.

Native to the Pacific Coast of North America and Asia, Pacific lampreys are an important ceremonial and subsistence food for Aboriginal peoples in the Columbia River basin. They are born in freshwater, swim out to the ocean as adults and return to freshwater to reproduce in similar habitats to Pacific salmon and trout. Adult lampreys can grow to approximately 75 cm long and use their sucker-like mouth to attach to other fish while in the ocean......... Posted by: Kelly      Read more         Source

July 12, 2010, 7:17 AM CT

New virus may pose risk to wild salmon

Farmed fish are an increasingly important food source, with a global harvest now at 110 million tons and growing at more than 8 percent a year. But epidemics of infectious disease threaten this vital industry, including one of its most popular products: farmed Atlantic salmon. Perhaps even more worrisome: these infections can spread to wild fish coming in close proximity to marine pens and fish escaping from them.

Heart and skeletal muscle inflammation (HSMI), an often fatal disease, was first detected in salmon on a farm in Norway in 1999, and has now been reported in 417 fish farms in Norway as well as in the United Kingdom. The disease destroys heart and muscle tissue and kills up to 20 percent of infected fish. Eventhough studies have indicated an infectious basis, recent efforts to identify the pathogen causing the disease have been unsuccessful. Now, using cutting-edge molecular techniques, an international team led by W. Ian Lipkin, MD, the John Snow Professor of Epidemiology and director of the Center for Infection and Immunity at Columbia University's Mailman School of Public Health, has found evidence that the disease appears to be caused by a previously unknown virus. The newly identified virus is related but distinct from previously known reoviruses, which are double-stranded RNA viruses that infect a wide range of vertebrates......... Posted by: Kelly      Read more         Source

July 12, 2010, 7:10 AM CT

Mexican salamander and mysteries of stem cells

Dr Andrew Johnson is speaking today (12 July) at the UK National Stem Cell Network annual conference. He and his team from the University of Nottingham have been using a Mexican aquatic salamander called an axolotl to study the evolution and genetics of stem cells - research that supports the development of regenerative medicine to treat the consequences of disease and injury using stem cell therapies. This team has observed that there are extraordinary similarities in the development of axolotls and mammals that provide unique opportunities to study the properties of embryonic stem cells and germ cells. These findings are underpinned by a novel theory of evolution that unifies the diversity of mechanisms in animal developmental into a single conceptual framework.

Dr Johnson said "We've produced evidence that pluripotency the ability of an embryonic stem cell to become absolutely any kind of cell is actually very ancient in evolutionary terms. Even though received wisdom is that it evolved with mammals, our research suggests that it was there all along, just not in a number of of the species that people use in the lab. In fact, pluripotent cells probably exist in the embryos of the simple animals from which amphibians evolved.

"Axolotls, unlike a number of of the frogs, fish, flies and worms that are used in the lab, have pluripotent cells in their embryos that are the equivalent to those found in embryos from mammals, in that they can produce germ cells, in addition to somatic cells, a property known as ground-state pluripotency. And from a practical perspective, axolotl embryos will provide a very useful tool for understanding how to manipulate embryonic stem cells for modern regenerative medicine"......... Posted by: Kelly      Read more         Source

July 7, 2010, 7:06 AM CT

Deworming lambs

Deworming lambs can be minimized with rotational grazing and checking the animals' eye color, as per an Agricultural Research Service (ARS) study.

Animal scientist Joan Burke at the ARS Dale Bumpers Small Farms Research Center in Booneville, Ark., and his colleagues made this finding as part of a continuing collaboration with scientists, veterinarians, and extension agents from the Southern Consortium for Small Ruminant Parasite Control.

The consortium was formed in response to the threats posed by worms resistant to parasiticides. Unnecessary de-worming speeds development of resistant worms. Reducing the use of conventional parasiticides fits well into organic and grass-fed management systems and meets consumer preferences of minimizing chemical residues in meat.

The blood-sucking worm, Haemonchus contortus, can cause severe anemia in animals. It is called the barber pole worm for the spiraling of its white, egg-filled ovaries around blood-filled intestines. Worldwide, they cost farmers and ranchers millions of dollars in losses. Animals shed worm eggs with their manure, and the larvae that hatch can be eaten by other livestock.

Burke and his colleagues observed that gel capsules filled with copper oxide wire particles eliminated the need for conventional dewormers in all but one case. And lambs that also rotated pastures needed fewer dewormings with the copper oxide pills......... Posted by: Kelly      Read more         Source

July 7, 2010, 6:59 AM CT

Lone whales shout to overcome noise

noise increases; and just like humans, at a certain point, it appears to become too costly to continue to shout, as per marine and acoustic scientists.

"The impacts of increases in ocean noise from human activities are a concern for the conservation of marine animals like right whales," said Susan Parks, assistant professor of acoustics and research associate, Applied Research Laboratory, Penn State. "The ability to change vocalizations to compensate for environmental noise is critical for successful communication in an increasingly noisy ocean".

Right whales are large baleen whales that often approach close to shore. They may have been given the name because they were the right whales to hunt as they are rich in blubber, slow swimming and remain afloat after death. Consequently, whalers nearly hunted these whales to extinction. Currently right whales are monitored to determine the health and size of the population. The northern and southern right whales are on the endangered species list.

"Right whale upcalls are used extensively for passive acoustic monitoring in conservation efforts to protect this endangered species," said Parks.

Whales produce upcalls, sometimes called contact calls, when they are alone or in the process of joining with other whales. An upcall begins low and rises in pitch. It is the most frequent call produced by right whales......... Posted by: Kelly      Read more         Source