Showing posts with label chytrid fungus. Show all posts
Showing posts with label chytrid fungus. Show all posts

Monday, November 14, 2011

Research team explores how microbial diversity on frogs defends against disease

Research team explores how microbial diversity on frogs defends against disease (Yes, Timing Of Release with Article #2 is Weird)
Press Release 11/8/11, Life Sciences Institute at Virginia Tech.

Amphibians are among the most threatened creatures on earth, with some 40 percent of amphibian species threatened or endangered. One of their primary threats is a rapidly spreading disease that attacks the skin cells of amphibians. "Chytridiomycosis, a fungal disease, has been a key factor in the extinctions of many species of frogs around the world," said Lisa Belden, associate professor of biological sciences in the College of Science at Virginia Tech.

Belden is leading a team of researchers from Tech, James Madison University, Villanova University, and the Smithsonian Institution who will study the microbial communities living on the skins of frogs that are surviving the fungal scourge. The effort is one of 11 new Dimensions of Biodiversity projects funded by the National Science Foundation (NSF) with the aim of transforming, by 2020, "how scientists describe and understand the scope and role of life on earth," according to an NSF news release.

For Belden's team, the lofty goals will be achieved through hands on work in Panama, where the spread of chytrid fungus has been extensively documented. Researchers will swab the skin of frogs in areas with and without chytrid to collect samples of the microbes that live there. They will then release the frogs and assess the microbial community, both in terms of what microbes are there and what they are doing functionally on the skin. To see what microbes are there, researchers will examine their DNA. To see what the microbes are doing, researchers will examine how well they inhibit the growth of the chytrid fungus, and also assess what chemical metabolites are being produced by the microbes. "We expect that in the presence of chytrid fungus, there will be strong selection for the bacteria to produce anti- chytrid fungus metabolites, regardless of what bacterial species are present on the skin," said Belden.

It is all about appreciating the diverse roles of microbes, Belden said. "We are used to equating microbes with germs that make us sick, but, in fact, many microbes are critical to health. Healthy humans, for instance, carry around about 3 pounds of microbes, largely in our guts. These microbes help us absorb our food, break down toxins, and prevent pathogens from gaining a foothold."

Belden's team is interested in whether microbial communities on the skin of frogs have a role in disease resistance, in particular to the devastating chytrid fungus. And if there is such immunity, does it rely on the same mechanism from one frog to another, on different species of frogs, and in different locations?
"Our long-term goal is to try to develop probiotics" - to share the biochemistry employed by beneficial microbes with frogs who need it, she said.

To advance that goal, Belden's team is working with Brian Gratwicke, a research biologist at the Smithsonian Conservation Biology Institute, and Roberto Ibáñez, a scientist at the Smithsonian Tropical Research Institute. As leaders of the Panama Amphibian Rescue and Conservation Project, they are maintaining captive colonies of endangered Panamanian frogs that are highly susceptible to the chytrid fungus. The hope is that the use of probiotics will someday allow release some of these species back into nature.

Members of the $2 million research project led by Belden are Virginia Tech colleagues Leanna House, assistant professor of statistics, and Roderick Jensen, professor of biological sciences; Reid Harris, professor of biology at James Madison University; Kevin Minbiole, assistant professor of organic and natural products chemistry at Villanova University; and the Smithsonian Institute scientists, Gratwicke and Ibáñez.

Jensen will guide the synthesis of the large amount of DNA sequence data that will be produced by the project, and House will develop new statistical methods to capture and analyze information from the DNA and metabolite datasets. "The bioinformatics and statistical analysis portions of the work are critical and provide the framework for advancing our knowledge in this system and also applying our findings to our systems," said Belden.

Minbiole has identified key antifungal metabolites from amphibians' skin bacteria. He will be doing the research on the metabolites the new project identifies. Harris, an ecologist, conducted the original experiments showing that amphibians' skin microbes are important in resisting chytrid fungus and will be involved with ecological surveys and experimental manipulations of the Panamanian frogs' microbes.
Contact: Susan Trulove
strulove@vt.edu
540-231-5646
Virginia Tech

Sunday, November 13, 2011

Frog-killer disease was born in trade (Via Herp Digest)

Frog-killer disease was born in trade - The global amphibian trade spread the lethal chytrid fungus, which is decimating frogs around the planet, and it now looks like it may have created the disease in the first place.
November 7, 2011 by Michael Marshall, New Scientist

The team behind this finding are calling for an amphibian quarantine to help slow the disease's spread. Rhys Farrer of Imperial College London and colleagues sequenced the genomes of 20 samples of the offending fungus, Batrachochytrium dendrobatidis (Bd), collected in Europe, Africa, North and South America and Australia.

They found that 16 of the 20 samples were genetically identical, belonging to a single strain called BdGPL that had spread to all five continents. Tests on tadpoles also revealed that the strain was extremely virulent.

BdGPL's genome showed that it had formed when two strains mated, some time in the past 100 years. The best and simplest explanation is that 20th-century trade, which shipped amphibians all over the world, enabled the mating, says Farrer's supervisor Matthew Fisher.

"We've got to restrict trade, or at least make sure that amphibians are not contaminated," says Fisher.

One approach would be for countries to quarantine all imported amphibians and only allow them to stay if they are uninfected.

When it emerged that trade was spreading chytrid, the World Organisation for Animal Health made the disease notifiable, meaning that countries must report whether they have it or not. But that doesn't stop it spreading.

The two places in most urgent need of protection are Madagascar and south-east Asia, says Fisher: "They're the last redoubts of uninfected amphibian species." Both are hotspots of amphibian diversity, and are clear of BdGPL. Madagascar remains uninfected despite rampant BdGPL in Africa, and a recent survey shows that Asian chytrid strains are not very virulent (PLoS One, DOI: 10.1371/journal.pone.0023179).

If BdGPL reaches these places, it could quickly devastate their frogs. Within months of it reaching Montserrat, in the West Indies, in early 2009, conservationists had to fly giant ditch frogs - also known as mountain chickens - out of the country to save them from extinction.

Countries that already have BdGPL should also institute quarantine, says Peter Daszak, president of EcoHealth Alliance in New York. "This research shows that recombination can occur and give rise to new virulent strains," he says. "Blocking introduction of new strains will cut down on this."

Daszak adds: "It will be hard to stop the spread of new lineages of Bd, but if we look at the devastation that this pathogen has already caused, we desperately need to try."

Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1111915108

Tuesday, April 26, 2011

Mitigating Amphibian Disease: Strategies to maintain wild populations and control chytridiomycosis (Via HerpDigest)

Mitigating Amphibian Disease: Strategies to maintain wild populations and control chytridiomycosis

7th Space Interactive, 2/14/11

Rescuing amphibian diversity is an achievable conservation challenge. Disease mitigation is one essential component of population management.

Here we assess existing disease mitigation strategies, some in early experimental stages, which focus on the globally emerging chytrid fungus Batrachochytrium dendrobatidis. We discuss the precedent for each strategy in systems ranging from agriculture to human medicine, and the outlook for each strategy in terms of research needs and long-term potential.

Results: We find that the effects of exposure to Batrachochytrium dendrobatidis occur on a spectrum from transient commensal to lethal pathogen.

Management priorities are divided between (1) halting pathogen spread and developing survival assurance colonies, and (2) prophylactic or remedial disease treatment. Epidemiological models of chytridiomycosis suggest that mitigation strategies can control disease without eliminating the pathogen.

Ecological ethics guide wildlife disease research, but several ethical questions remain for managing disease in the field.

Conclusions: Because sustainable conservation of amphibians in nature is dependent on long-term population persistence and co-evolution with potentially lethal pathogens, we suggest that disease mitigation not focus exclusively on the elimination or containment of the pathogen, or on the captive breeding of amphibian hosts. Rather, successful disease mitigation must be context specific with epidemiologically informed strategies to manage already infected populations by decreasing pathogenicity and host susceptibility.

We propose population level treatments based on three steps: first, identify mechanisms of disease suppression; second, parameterize epizootiological models of disease and population dynamics for testing under semi-natural conditions; and third, begin a process of adaptive management in field trials with natural populations.

Author: Douglas WoodhamsJaime BoschCheryl BriggsScott CashinsLeyla DavisAntje LauerErin MuthsRobert PuschendorfBenedikt SchmidtBrandon SheaforJamie Voyles
Credits/Source: Frontiers in Zoology 2011, 8:8

Friday, February 4, 2011

Bd Invades Everywhere (Via HerpDigest)

Bd Invades Everywhere
Smithsonoanian Tropical Research Inst. 1/31/10

Bd is a waterborne pathogen, and until recently, was thought to be limited by temperature, but the extent to which it persists and causes disease in amphibians at lower elevations in the neotropics is not known


A group of scientists led by Vanessa L. Kilburn of McGill University and including Roberto Ibáñez, director of STRI´s Amphibian Rescue and Conservation Center in Panama, Oris Sanjur and Eldredge Bermingham, also from STRI, Justin P. Suraci of Simon Frazer University and David M. Green of McGill, has just published an article in EcoHealth on the "Ubiquity of the pathogenic chytrid fungus, Batrachochytrium dendrobatidis, in anuran communities in Panama."

Batrachochytrium dendrobatidis (Bd) has been implicated as the main driver of many enigmatic amphibian declines in neotropical sites at high elevations.

Bd is a waterborne pathogen, and until recently, was thought to be limited by temperature, but the extent to which it persists and causes disease in amphibians at lower elevations in the neotropics is not known. It also is unclear by what mechanisms Bd emerged as a pathogenic organism; there is debate as to whether it is endemic to the region and for some reason its pathogenicity increased, or if it is a new pathogen to the region.

In this research, conducted in western Panama in 2006, several study sites were established along the epidemic gradient caused by Bd, including sites where the epidemic had not yet arrived, places right in the middle of the epidemic and others two and 10 years after the epidemic. Other sites were also established along an altitude gradient between 45 and 1,215 meters above sea level. 

After analyzing samples obtained from the skin of the frogs using quantitative PCR analyses to detect the fungus, the scientists found that there were infected frogs everywhere, including sites where the fungus arrived years ago, as well as lowland sites.

When comparing lowland frog abundance with previous years, the scientists also noticed a decline in frog diversity and abundance.

It is very difficult to know if Bd is an endemic organism or a new, recent arrival. However, based on the results of this study and current knowledge, the scientists maintain the idea that chytridiomycosis is new and invasive and that it is spreading all over the world.

Sunday, September 26, 2010

Service Seeks Information on Petition To Halt Spread of Amphibian Disease-Chytrid Fungus (Via Herp Digest)

Service Seeks Information on Petition To Halt Spread of Amphibian Disease-Chytrid Fungus (Batrachochytrium dendrobatidis or Bd) as "Injurious Wildlife" Under The Lacey Act

9/17/10 The U.S. Fish and Wildlife Service today announced it has posted a notice in the Federal Register seeking information concerning the possible designation of all live amphibians or their eggs that are infected with
chytrid fungus (Batrachochytrium dendrobatidis or Bd) as "injurious wildlife" under the Lacey Act.

The fungus causes chytridiomycosis, a disease deadly to amphibians, and has been identified as a primary factor leading to the listing of a number of amphibian species as threatened or endangered. If finalized, the designation as injurious would require a health certification that live amphibians or their eggs are not infected with chytrid fungus prior to import or transportation across state lines.

The Notice of Inquiry will publish in the Federal Register on September 17, 2010, and explains the chytrid fungus issue and asks the public to provide information on the subject. The submissions will be reviewed and a decision made whether to proceed with a proposed rule or to take no further action.

"The worldwide decline of amphibians is of great concern to us. Chytrid is attributed as a major cause of this amphibian mortality. We understand that halting the spread of the fungus or eradicating it will take more than just regulating importation and transportation of infected amphibians, but it is a major step in the right direction," said Acting Director Rowan Gould.

The petition and the Notice of Inquiry are available at: http://www.regulations.gov under Docket No. FWS-R9-FHC-2009-0093. The public will have until December 16, 2010, to provide information on the
subject of the petition.

Under the Lacey Act, the Department of the Interior is authorized to regulate the importation and interstate transport of wildlife species determined to be injurious to humans; the interests of agriculture, horticulture or forestry; or the welfare and survival of wildlife resources of the United States. Current regulations prohibit the release into the wild of all species of live amphibians or their eggs, except as authorized. A listing under the Lacey Act would not affect a person or institution that currently owns an amphibian and does not transport it to
another state or U.S. territory.

For information on injurious wildlife and how to send comments, as well as links to partner agencies, visit:
http://www.fws.gov/fisheries/ans/ANSInjurious.cfm. Contact: Valerie Fellows 703/358 2285
Valerie_Fellows@fws.gov

Service Seeks Information on Petition To Halt Spread of Amphibian Disease-Chytrid Fungus (Via Herp Digest)

Service Seeks Information on Petition To Halt Spread of Amphibian Disease-Chytrid Fungus (Batrachochytrium dendrobatidis or Bd) as "Injurious Wildlife" Under The Lacey Act

9/17/10 The U.S. Fish and Wildlife Service today announced it has posted a notice in the Federal Register seeking information concerning the possible designation of all live amphibians or their eggs that are infected with
chytrid fungus (Batrachochytrium dendrobatidis or Bd) as "injurious wildlife" under the Lacey Act.

The fungus causes chytridiomycosis, a disease deadly to amphibians, and has been identified as a primary factor leading to the listing of a number of amphibian species as threatened or endangered. If finalized, the designation as injurious would require a health certification that live amphibians or their eggs are not infected with chytrid fungus prior to import or transportation across state lines.

The Notice of Inquiry will publish in the Federal Register on September 17, 2010, and explains the chytrid fungus issue and asks the public to provide information on the subject. The submissions will be reviewed and a decision made whether to proceed with a proposed rule or to take no further action.

"The worldwide decline of amphibians is of great concern to us. Chytrid is attributed as a major cause of this amphibian mortality. We understand that halting the spread of the fungus or eradicating it will take more than just regulating importation and transportation of infected amphibians, but it is a major step in the right direction," said Acting Director Rowan Gould.

The petition and the Notice of Inquiry are available at: http://www.regulations.gov under Docket No. FWS-R9-FHC-2009-0093. The public will have until December 16, 2010, to provide information on the
subject of the petition.

Under the Lacey Act, the Department of the Interior is authorized to regulate the importation and interstate transport of wildlife species determined to be injurious to humans; the interests of agriculture, horticulture or forestry; or the welfare and survival of wildlife resources of the United States. Current regulations prohibit the release into the wild of all species of live amphibians or their eggs, except as authorized. A listing under the Lacey Act would not affect a person or institution that currently owns an amphibian and does not transport it to
another state or U.S. territory.

For information on injurious wildlife and how to send comments, as well as links to partner agencies, visit:
http://www.fws.gov/fisheries/ans/ANSInjurious.cfm. Contact: Valerie Fellows 703/358 2285
Valerie_Fellows@fws.gov