September 26, 2007, 8:17 PM CT

Emphasizing the 'precision' in precision agriculture

New protocol and software developments are helping farmers put the precision back in precision agriculture by making it easier for growers to use previously ineffectual soil and environmental data to manage their crops.

Historically, gaps between scientists and producers, as well as lack of capacity to transform data into relevant decisions, have all contributed to data languishing on hard drives rather than being used to inform growing decisions.

Using software available online, scientists from the Australian Centre for Precision Agriculture (ACPA) at the University of Sydney have developed a simplified protocol to teach growers how to convert complex yield and soil data into pertinent information. The resulting data and maps, when interpreted with local agronomic knowledge, can be used to make class-specific management decisions.

The protocol provides [growers] with the ability to experiment on their fields with different combinations of temporal data layers to improve their understanding of how their fields respond, said James Taylor and his team of scientists who worked with a range of growers to develop the methodology.

The scientists article in the September/October 2007 Agronomy Journal details their work in advancing field management, in particular their efforts to move away from treating all zones uniformly to more site-specific management. After receiving protocol training on how to analyze and apply field data, Australian growers were able to utilize the protocol and software to develop better field management, including implementing site-specific nutrient and pest management therapys......... Posted by: Erica      Read more         Source

September 26, 2007, 8:10 PM CT

Nutrient Pollution Drives Frog Deformities

High levels of nutrients used in farming and ranching activities fuel parasite infections that have caused highly publicized frog deformities in ponds and lakes across North America, as per a new study led by the University of Colorado at Boulder.

The study showed increased levels of nitrogen and phosphorus cause sharp hikes in the abundance and reproduction of a snail species that hosts microscopic parasites known as trematodes, said Pieter Johnson of the University of Colorado, Boulder. The nutrients stimulate algae growth, increasing snail populations and the number of infectious parasites released by snails into ponds and lakes. The parasites subsequently form cysts in the developing limbs of tadpoles causing missing limbs, extra limbs and other severe malformations, Johnson said.

"This is the first study to show that nutrient enrichment drives the abundance of these parasites, increasing levels of amphibian infection and subsequent malformations," said Johnson. "The research has implications for both worldwide amphibian declines and for a wide array of diseases potentially associated with nutrient pollution, including cholera, malaria, West Nile virus and diseases affecting coral reefs".

Johnson is the lead author of a study on the subject published online the week of Sept. 24 in the Proceedings of the National Academy of Sciences. The National Science Foundation funded the work......... Posted by: Kelly      Read more         Source

September 26, 2007, 8:09 PM CT

Interbreeding Between Invasive and Native Salamander Species

Interbreeding between the California Tiger Salamander--which is a native, endangered species--and the invasive Barred Tiger Salamander has produced a swarm of hybrid salamanders that is more likely to survive than either parent species, as per a new study.

Found in Salinas, California, the swarm of hybridized salamanders may comprise the first population of sustainable hybrids created by an interbreeding involving an endangered species, and is among the first known sustainable populations of a hybrid animal.

The conservation issues raised by the discovery of the salamander hybrid may "serve as a model" for those issues to be raised by future discoveries of hybrids created by interbreeding between an endangered species and an invasive species, says Brad Shaffer of the University of California, who is a co-author of the study. Because of advances in genetic analyses and because of increases in invasive species, Shaffer expects increasing numbers of hybrids to be discovered in the future.

The study of the hybridization of the California Tiger Salamander and the invasive Barred Tiger Salamander, which was introduced to the study area about 50 years ago as fishing bait, is described in the September 17 issue of The Proceedings of the National Academy of Sciences. This research was partially funded by the National Science Foundation (NSF)......... Posted by: Kelly      Read more         Source

September 26, 2007, 8:04 PM CT

Hybrid Salamanders Contradict Common Wisdom

A new UC Davis study not only has important findings for the future of California tiger salamanders, but also contradicts prevailing scientific thought about what happens when animal species interbreed.

The study, by former UC Davis doctoral student Benjamin Fitzpatrick (now on the faculty of University of Tennessee, Knoxville) and professor Bradley Shaffer, was published recently in the Proceedings of the National Academy of Sciences' online edition.

The salamander experts studied the survival rates and genetic makeup of three types of salamanders: native California tiger salamanders (Ambystoma californiense), which are protected under the U.S. Endangered Species Act; barred tiger salamanders that were introduced in California from Texas in the 1950s (Ambystoma tigrinum mavortium); and the hybrid offspring born when the two species mated.

They observed that more of the hybrid young survived in the wild than did young of the native or the introduced species -- quite a surprise, since animal hybrids are commonly less fit than their parents ("hybrid vigor" is largely limited to plant crosses).

That raises difficult questions for managing endangered native salamander populations, Shaffer said. Some conservationists might say that hybrids are an acceptable change, since they are favored by natural selection, and "improve" the original species. Others might consider hybrids to be genetically impure and regard them as threats to the native salamanders, their competitors and their prey......... Posted by: Kelly      Read more         Source

September 26, 2007, 8:01 PM CT

Keeping a Diverse Planet

Variation in plants and animals gives us a rich and robust assemblage of foods, medicines, industrial materials and recreation activities. But human activities are eliminating biological diversity at an unprecedented rate.

A new UC Davis study offers clues to how these losses relate to one another -- information that is essential as researchers and land managers strive to protect the remaining natural variation.

Sharon Strauss, a professor of evolution and ecology, and former doctoral student Richard Lankau (now a post-doctoral researcher at the University of Missouri-St. Louis and the University of Illinois), studied competition among genetically varied plants of one species (black mustard, Brassica nigra), and among black mustard and plants of other species.

"This is one of the first studies to show that genetic diversity and species diversity depend on each other," Lankau said. "Diversity within a species is necessary to maintain diversity among species, and at the same time, diversity among species is necessary to maintain diversity within a species.

"And if any one type is removed from the system, the cycle can break down, and the community becomes dominated by a single species".

The research was funded by the National Science Foundation. The paper, titled "Mutual feedbacks maintain both genetic and species diversity in a plant community," was reported in the Sept. 14 issue of the journal Science......... Posted by: Janet      Read more         Source

September 26, 2007, 7:53 PM CT

Working to save microscopic threatened species

The Smithsonians National Zoo recently acquired 12,000 new animalsmicroscopic Elkhorn coral larvae harvested by National Zoo researchers in Puerto Ricoas part of an international collaborative program to raise the threatened species. National Zoo researchers hope to one day return the animals, once they are grown, to their wild ocean habitat.

In August, Zoo Reproductive Scientist Dr. Mary Hagedorn and Invertebrates Keeper Mike Henley traveled to Puerto Rico with marine researchers involved with SECORE (SExual COral REproduction) to collect and artificially inseminate coral. Hagedorn is pioneering the cyropreservation (freezing, storing and thawing) of coral sperm and eggs. Working in collaboration with SECORE, she is trying to create a genome resource bank, which will help preserve the genetic diversity of coral.

Hagedorn, Henley and the team captured spawning coral gametes in nets during night dives and transferred them back to their laboratory on the beach for research and artificial inseminationoften working until 3 a.m. Using 75 feet of specially designed flexible PVC piping that could be bent around the coral so as not to harm it, the team created a water-flow system that allowed water from the ocean to continuously flow in and out of the coral larvae enclosure located in the beachfront laboratory. Keeping the water fresh and at a constant temperature is essential for corals that flourish in stable environments......... Posted by: Kelly      Read more         Source

September 26, 2007, 7:46 PM CT

How and why people respond differently to drugs

While prescription medications work successfully to cure an ailment in some people, in others the same dose of the same drug can cause an adverse reaction or no response at all.

As per a research team led by Sean Cutler, an assistant professor of plant cell biology at UC Riverside, such variation in drug responses can be analyzed by studying much simpler organisms like plants.

The genetics behind variable drug responses is not peculiar to humans but exists also in other branches on the tree of life, Cutler said. We can harness simple organisms to understand more about the genetics and biochemistry of variable drug responses, which could help uncover new factors that contribute to variable drug responses in humans.

Study results appear in the Sept. 23 online publication of Nature Chemical Biology

Focusing on Arabidopsis thaliana, a weedy plant in the mustard family, Cutlers lab discovered a key protein in the plant that creates drug resistance. Called UGT (UDP-glycosyltransferase), the protein is a member of a family of proteins that also affect drug sensitivity in humans.

Similar biochemical processes are affecting drug sensitivity in both plants and animals, said Cutler, who joined UCRs Department of Botany and Plant Sciences and the Center for Plant Cell Biology in January 2007. These similarities suggest that plants can be useful for studying problems of human interest like drug responses......... Posted by: Erica      Read more         Source

September 25, 2007, 10:00 PM CT

How The Zebrafish Gets His Stripe

Researchers have discovered how the zebrafish (Danio rerio) develops one of its four stripes of pigment cells.

Their findings add to the growing list of tasks carried out by an important molecule that is involved in the arrangement of everything from nerve cells to reproductive cells in the developing embryo.

The research focused on a particular zebrafish mutant known as choker, which is distinctive because one of the four stripes running down its side is missing, and it has a dark collar around its neck instead.

Dark spots and stripes in fish, amphibians and reptiles are commonly caused by a type of cell, known as a melanophore, which contains high quantities of the pigment melanin.

Using time-lapse photography, the team put together movies showing how the melanophores migrate in developing embryos of both the wild-type (naturally occurring) zebrafish and the choker mutant.

At first, cells migrate through the neck region in both wild-type and choker mutant fish to generate two stripes. Then, whilst cell migration ceases in the neck region of the wild-type embryo, melanophores in the choker mutant exit from the two stripes and busily cluster around the collar region of the developing fish.

"It is as though someone has put up 'keep off the grass' signs in the wild-type zebrafish to keep the melanophores in separate paths (stripes)," said Dr Robert Kelsh from the University of Bath who led the study which was reported in the journal Development......... Posted by: Kelly      Read more         Source

September 25, 2007, 9:47 PM CT

Spatial patterns in tropical forests

The high biodiversity in tropical forests has both fascinated and puzzled ecologists for more than half a century. In the hopes of finding an answer to this puzzle, ecologists have turned their attention to the spatial patterns of such communities and mapped the location of each tree with a stem larger than a pencil in plots covering 25 to 52ha of tropical forest around the world. As per a research findings published in The American Naturalist a German - Sri Lankan research team has now undertaken thousands of spatial pattern analyses to paint an overall picture of the association between tree species in one of these plots in Sri Lanka.

"The problem of studying spatial association between species is that habitat association confounds the effect of plant-plant interactions" says Dr Wiegand, senior scientist at the Helmholtz Centre for Environmental Research in Leipzig, Gera number of. The breakthrough in their analysis is that it allowed them to disentangle these two effects and to look in a new way at their data. "From prior studies we knew that growth and survival of trees depends quite strongly on their neighbors" say Savitri Gunatilleke and her husband Nimal, both professors at the University of Peradeniya, "we had therefore expected to find strong signatures of positive or negative interactions between species in our data". "However, the fact that not more than 5 percent of the 2070 species pairs we have analyzed showed significant associations is quite remarkable." A conclusion of their study is that neighborhood-dependent processes may equilibrate, thereby producing neutral association patterns in the spatial distribution of trees. "This is certainly not the last word in this debate," says Wiegand "but it is a step towards an understanding of the complexities of the origin and maintenance of species richness in tropical forests"......... Posted by: Erica      Read more         Source

September 25, 2007, 9:12 PM CT

City birds better than rural species in coping

Birds that hang out in large urban areas seem to have a marked advantage over their rural cousins they are adaptable enough to survive in a much larger range of conditions.

In fact, new research from the University of Washington suggests that the adaptability of a number of urban bird species means they don't just survive but actually thrive in what might be considered to be a very challenging environment.

"The urban habitat is commonly more severe than the habitats these birds historically occupied. Urban habitats aren't easy, so the birds have to have developed coping mechanisms," said John Wingfield, a UW biology professor involved in the research.

The study was led by Frances Bonier, a postdoctoral researcher in biology at Virginia Polytechnic Institute, who did the work as a UW doctoral student before moving to Virginia Tech. Co-author Paul Martin, now an assistant professor of biology at Queens University in Kingston, Ontario, also took part in the research as a UW doctoral student.

Ornithologists, biologists and birdwatchers around the world were sent questionnaires that asked them to list 10 common native breeding birds found in their cities. The responses produced data on 217 urban bird species from 73 of the world's largest cities and 247 rural species. To be considered "rural," a species could not be described as breeding in human-disturbed habitats such as towns and cities, and its natural breeding distribution must overlap at least one of the large cities, implying that at one time the species occupied the area where the city is now......... Posted by: Kelly      Read more         Source