Mostrando entradas con la etiqueta Frogs. Mostrar todas las entradas
Mostrando entradas con la etiqueta Frogs. Mostrar todas las entradas

viernes, 7 de febrero de 2014

nsf.gov - National Science Foundation - NSF-funded researchers describe their cutting-edge brain research

Why and how are researchers studying the brains of mice, octopuses, zebra fish, frogs, lizards and cichlid fish?

Partha Mitra is contributing to the construction of the first 3-D map of the mouse brain.
Partha Mitra is contributing to the construction of the first 3-D map of the mouse brain.
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February 6, 2014
Our understanding of the brain is still downright rudimentary compared to our understanding of other organs. To revolutionize brain science, President Obama in April 2013 announced the Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative, which is co-led by the National Science Foundation (NSF).
But even before BRAIN was created, NSF had a long history of funding innovative basic research focused on the brain. NSF's research approaches integrate information, methods and models at scales ranging from the molecular level to the behavioral level; they also draw from multiple scientific, engineering and computational disciplines.
In addition, some NSF-funded scientists are examining how changes in brain structure and activity correlate with different external environments and behavioral changes. These factors, along with genetic analyses, are--in many cases--easier to study in relatively simple organisms than in humans. Also, by identifying features that are similar and different across species, and by studying organisms throughout their lifespans, scientists are advancing their understanding of how nervous systems work.
Featured here are video interviews with selected NSF-funded brain researchers about their cutting-edge, multidisciplinary research on mice, octopuses, zebrafish, frogs, lizards and cichlids. These interviews were recorded at the NSF Workshop on Phylogenetic Principles of Brain Structure and Function at the Howard Hughes Medical Institute's Janelia Farm Research Campus in Ashburn, Va., in October 2013.
Partha Mitra of Cold Spring Harbor Laboratory is currently focused on the Mouse Brain Architecture Project (MAP), which is aimed at creating 3-D maps of the mouse brain at various scales. (The mouse brain is 1/1000 of the volume of the human brain.) MAP is also dedicated to relating brain circuits (groups of neurons) to behavior.
One way that Mitra is contributing to MAP is by mapping the projection patterns of groups of similarly organized neurons across regions of the mouse brain. He is thereby helping to identify how neurons are connected and communicate across regions of the brain.
In addition, Mitra is applying his background in theoretical physics to his studies of the mouse brain. He is doing so by working to identify ways to apply to brain research methods in statistical physics that are used to analyze the macroscopic behavior of large, distributed networks.
Specifically, these methods have been used by engineers to analyze technologically important networks--such as power grids and coordinated formations of vehicles--and to help design such networks with wanted properties. If these methods can be applied to brain research, they may enable researchers to identify and prioritize important aspects of brain networks for study--helping to distinguish microscopic details that play important roles in overall behaviors from those that do not.
Once the map of the mouse brain is completed and analyzed, it will be the first-of-its-kind map of a whole vertebrate brain. MAP's future goals include mapping connectivity patterns in the marmoset monkey brain and ultimately in the human brain.
Information and images from MAP are publically available on MAP's website.
Clifton Ragsdale of the University of Chicago is researching the nervous system of the octopus, which is a successful predator partly because it has excellent eyesight--the best of any invertebrate. The octopus's excellent eyesight enables it to visually zero in and focus on prey.
What's more, each of the octopus's eight agile, boneless arms has about 44 million nerve cells (or almost 10 percent of all of its neurons). These arm neurons are connected to the animal's brain.
When an octopus spots a tasty-looking fish, the information it collects about this prey travels from the animal's eye to its brain. This information then travels through its arm neurons to help these soft-bodied contortionists determine how to snatch the prey.
Conversely, tactile information, such as the feel of a crab's rough shell, travels back through the octopus's arm neurons to its brain's learning and memory centers to help these clever animals improve their hunting skills.
Ragsdale is currently pioneering the use of modern molecular techniques to study how the octopus's unique nervous system processes visual information, and if its processing system significantly differs from those of vertebrates.
Melina Hale of the University of Chicago is studying neuronal circuits in zebrafish that generate startle responses. (Yes, the kinds of startle responses that are produced by sudden sounds or movements.)
Because little is known about how circuits operate in any organism and because startle responses are controlled by relatively simple circuits, an improved understanding of the circuitry of the zebrafish's startle responses is expected to help lay the groundwork for research on more complicated circuits.
The zebrafish--a small common aquarium fish--serves as an excellent fish for laboratory studies because molecular tools are available for experimenting with its neurons. The zebrafish can also be easily maintained and reproduces and develops rapidly. Also, young zebrafish are transparent and so their nervous systems are easily observable.
Walter Wilczynski of Georgia State University is researching how non-mammals signal one another in mating competitions, and how these signals influence the behavior of individual males and females. According to Wilczynski's research, an individual's behavioral responses to such signals and whether it loses or wins a mating competition may modify its brain in ways that may influence its future behavior.
Wilczynski's research is important because a) competition for reproduction is fundamental to all of biology; and b) Wilczynski uses model organisms whose social interactions are, in many ways, simplified versions of human social interactions. These model organisms include frogs, which communicate through vocal calls, and lizards, which communicate through visual displays.
Hans Hofmann of the University of Texas, Austin, is researching the influences of environment and genetics on the brains and behavior of cichlid fish. Cichlids provide excellent model organisms for such studies because thousands of species of cichlids have evolved; many of these species are genetically similar but behaviorally and socially different from one another. Hofmann is using the diversity of cichlid species to help identify which genes regulate various behaviors and evaluate how different social environments affect brain function and behavior.
Mammals and cichlids share many of the same genetic mechanisms that are sensitive to social environments and help govern mating systems (such as monogamous vs. non-monogamous systems) and parental care systems (such as those that involve fatherly caretaking vs. those that don't). Therefore, research on the effect of social environments on cichlid brains, genetics and behavior may ultimately help advance our understanding of differing human mating and parental care systems.
-- Lily Whiteman, NSF (703) 292-8310 lwhitema@nsf.gov
-- Sarah Bates, NSF (703) 292-7738 Sabates@nsf.gov
Investigators Melina Hale
Hans Hofmann
Partha Mitra
Clifton Ragsdale
Walter Wilczynski
Related Institutions/Organizations Harvard University
University of Chicago
Cold Spring Harbor Laboratory
Georgia State University Research Foundation, Inc.
Total Grants $1,634,318
Related WebsitesNSF fact sheet on BRAIN Initiative:
 http://www.nsf.gov/news/news_summ.jsp?cntn_id=128960
NSF article on BRAIN Initiative:
 http://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=128239
Partha Mitra
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Partha Mitra tells why and how he is helping to map the mouse brain.
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Clifton Ragsdale
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Clifton Ragsdale reveals why octopuses are such successful predators.
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Melina Hale
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Melina Hale explains how her research of zebrafish are helping to advance brain research.
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Walter Wilczynski
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Wilczynski discusses research on the responses by non-mammals to signals during mating competitions.
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Hans Hofmann
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Hofmann explains how environment and genetics influence the brains and behavior of cichlid fish.
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The National Science Foundation (NSF).
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
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jueves, 14 de febrero de 2013

nsf.gov - News - Biodiversity Protects Against Disease, Scientists Find

Discovery resulted from study of amphibians in ponds.-

 Image of frogs with deformed limbs in a pond.
Scientists peer into a pond containing amphibians with deformed limbs.
Credit: Dave Herasimtschuk/Freshwaters Illustrated
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 A northern red-legged frog with limb deformities sitting on a leaf

A northern red-legged frog with limb deformities seems to watch researchers at work.
Credit: Dave Herasimtschuk/Freshwaters Illustrated
Download the high-resolution JPG version of the image. (215 KB)  Scientists searching a pond

Scientists search ponds for deformed amphibians.
Credit: Dave Herasimtschuk/Freshwaters Illustrated
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Biologist Pieter Johnson holding snails in his hand
Biologist Piet Johnson collects snails for parasite testing.
Credit: Dave Herasimtschuk/Freshwaters Illustrated
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herons and egrets
Amphibian-eating birds such as herons and egrets are part of the aquatic parasite cycle.
Credit: Dave Herasimtschuk/Freshwaters Illustrated
Download the high-resolution JPG version of the image. (107 KB) 

A northern leopard frog with deformed limbs from a parasite infection.

This northern leopard frog has deformed limbs from a parasite infection.
Credit: Dave Herasimtschuk/Freshwaters Illustrated
Download the high-resolution JPG version of the image. (145 KB)
The richer the assortment of amphibian species in a pond, the more protection that community of frogs, toads and salamanders has against a parasitic infection that can cause severe deformities, including the growth of extra legs.
The findings, published in a paper in this week's issue of the journal Nature, support the idea that greater biodiversity in large-scale ecosystems, such as forests or grasslands, may also provide greater protection against diseases, including those that affect humans.
A larger number of mammal species in an area may curb cases of Lyme disease, while a larger number of bird species may slow the spread of West Nile virus.
"How biodiversity affects the risk of infectious diseases, including those of humans and wildlife, has become an increasingly important question," said Pieter Johnson, an ecologist and evolutionary biologist at the University of Colorado Boulder, and the lead author of the paper.
"But as it turns out, solidly testing these links with realistic experiments has proven very challenging in most systems."
Researchers have struggled to design comprehensive studies that could illuminate the possible connection between disease transmission and the number of species living in complex ecosystems.
Part of the problem is the enormous number of organisms that may need to be sampled, and the vast areas over which those organisms may roam.
This study overcame that problem by studying smaller, easier-to-sample ecosystems, the scientists say.
"The research reaches the surprising conclusion that the entire set of species in a community affects susceptibility to disease," said Doug Levey, program director in the National Science Foundation (NSF)'s Division of Environmental Biology, which funded the research. "Biodiversity matters."
Johnson and colleagues visited hundreds of ponds in California, recording the types of amphibians living there as well as the number of snails infected by the pathogen Ribeiroia ondatrae.
Snails are an intermediate host used by the parasite during part of its life cycle.
"One of the great challenges in studying the diversity-disease link has been collecting data from enough replicate systems to differentiate the influence of diversity from background 'noise,'" Johnson said.
"By collecting data from hundreds of ponds and thousands of amphibian hosts, we were able to provide a rigorous test of this hypothesis, which has relevance to a wide range of disease systems."
The researchers buttressed field observations with laboratory tests designed to measure how prone to infection each amphibian species is, and by creating pond replicas using large plastic tubs stocked with tadpoles that were exposed to a known number of parasites.
All the experiments told the same story.
Greater biodiversity reduced the number of amphibian infections and the number of deformed frogs.
The scientists spent three years sampling 345 wetlands and recording malformations--which include missing, misshapen or extra sets of hind legs--caused by parasitic infections in 24,215 amphibians.
The results showed that ponds with half a dozen amphibian species had a 78 percent reduction in parasite transmission compared to ponds with just one amphibian species.
The reason for the decline in parasitic infections as biodiversity increases is likely related to the fact that ponds add amphibian species in a predictable pattern, with the first species to appear being the most prone to infection and the later species to appear being the least prone.
The researchers found that in a pond with just one type of amphibian, that amphibian was almost always the Pacific chorus frog, a creature that's able to rapidly reproduce and quickly colonize wetland habitats, but which is also especially vulnerable to infection and parasite-induced deformities.
On the other hand, the California tiger salamander was typically one of the last species to be added to a pond community--and also one of the most resistant to parasitic infection.
Therefore, in a pond with greater biodiversity, parasites have a higher chance of encountering an amphibian that is resistant to infection, lowering the overall success rate of transmission between infected snails and amphibians.
This same pattern--of less diverse communities being made up of species that are more susceptible to disease infection--may well play out in more complex ecosystems, Johnson said.
That's because species that disperse quickly across ecosystems appear to trade off the ability to quickly reproduce with the ability to develop disease resistance.
The recent study also reinforces the connection between deformed frogs and parasitic infection.
In the mid-1990s reports of frogs with extra, missing or misshapen legs skyrocketed, attracting widespread attention in the media and motivating scientists to try to figure out the cause.
Johnson was among the researchers who found evidence of a link between infection with Ribeiroia and frog deformities, though the apparent rise in reports of deformations, and its underlying cause, remained controversial.
While the new study has implications beyond parasitic infections in amphibians, it does not mean that an increase in biodiversity always results in a decrease in disease, Johnson said.
Other factors also affect rates of disease transmission.
For example, a large number of mosquitoes hatching in a particular year increases the risk of contracting West Nile virus, even if there has been an increase in the biodiversity of the bird population.
Birds act as "reservoir hosts" for West Nile virus, harboring the pathogen indefinitely with no ill effects, then passing on the pathogen.
"Our results indicate that higher diversity reduces the success of pathogens in moving between hosts," Johnson said.
"But if infection pressure is high, there will still be a significant risk of disease. Biodiversity will simply dampen transmission success."
Co-authors of the paper are Dan Preston and Katie Richgels of the University of Colorado Boulder, and Jason Hoverman of Purdue University.
In addition to NSF, the research was funded by the National Geographic Society and the David and Lucile Packard Foundation.
-NSF-
Media Contacts Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
Laura Snider, University of Colorado Boulder (303) 735-0528 laura.snider@colorado.edu
Related WebsitesNSF Special Report: Ecology and Evolution of Infectious Diseases: http://www.nsf.gov/news/special_reports/ecoinf/index.jsp
The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2012, its budget is $7.0 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives over 50,000 competitive requests for funding, and makes about 11,000 new funding awards. NSF also awards nearly $420 million in professional and service contracts yearly.
Useful NSF Web Sites:
NSF Home Page: http://www.nsf.gov
NSF News: http://www.nsf.gov/news/
For the News Media: http://www.nsf.gov/news/newsroom.jsp
Science and Engineering Statistics: http://www.nsf.gov/statistics/
Awards Searches: http://www.nsf.gov/awardsearch/

 The National Science Foundation (NSF).

 Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com
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