News / Science & Technology

Scientists Draw First Genetic Roadmap of Amphibian

X. tropicalis (left) and X. laevis (right)
X. tropicalis (left) and X. laevis (right)
Jessica Berman

Scientists have completed the first genetic blueprint of an amphibian, a clawed African frog, which they say is among the last vertebrates to have its DNA sequenced.  Researchers hope the work will shed light on the effects of chemicals called endocrine disruptors on humans and help preserve endangered frog species.  

Xenopus tropicalis, often called the Western clawed frog, is one of 20 frog species native to sub-Saharan Africa.  Its cousin, X. laevis, is now commonly used in laboratories where studies of its large eggs have helped scientists understand the development of fertilized eggs into embryos.

With its genetic sequence now in hand, the smaller tropicalis should help researchers link genetic changes to the developmental milestones in both species as well as in human embryos, which scientists say are more difficult to study.

Uffe Hellsten, with the Department of Energy Joint Genome Institute in Walnut Creek, California, is one of almost 50 scientists worldwide who helped to create the new catalog of the frog's DNA.

Hellsten says the genetic blueprint opens up several other avenues of research by comparing the tropicalis' genes to those of other vertebrates, including humans. "To mention an example, we have found that about 80 percent of all genes that are known to be associated with human disease have a counterpart in frog.  Obviously this opens up the possibility of enhancing our understanding of many of those diseases by studying disease models in frog," he said.

Scientists say tropicalis and humans share 1,700 disease-related genes. They say the frog gives scientists a living laboratory in which to learn how those genes cause illness in people.

Hellsten notes that a  comparison of regions around specific genes in the frog, chicken and human shows that all three genomes are remarkably similar. He says scientists are looking at fragments of an ancient chromosome that belonged to the common ancestor of all mammals, birds and amphibians before they diverged 360 million years ago.

Hellsten says tropicalis has about 20,000 genes compared to 23,000 genes in human.  The frog shares many biological features with humans, including development of nervous, skeletal and immune systems.

In general, frogs are popular research subjects because they take up less room in the lab and have a shorter lifecycle, as little as 4 months, and their eggs are relatively easy to manipulate.

Frogs rose to prominence as prized experimental animals in the 1940's when scientists discovered they could inject the urine of pregnant woman into a frog and it would produce eggs.

Since then, there's been interest in frogs as models for the study of endocrine disruptors. These artificial chemicals - found in industrial products such as agricultural insecticides - often pollute the lakes and streams in which the frogs live.

The endocrine disruptors mimic the frogs' reproductive hormones, causing bizarre deformities in developing amphibians, including the growth of female sex organs in male frogs.  The chemicals are also blamed for causing a major decline in frog populations over the past several decades.

As a result, says Hellsten, scientists are eager to figure out exactly how these chemicals do their damage. "We can hope to actually study the effect of such disruptors at a molecular level and understand better how they interact.  And research like this could hopefully in time not only help humans, because humans are also sensitive to such chemicals, but also help preserve the frog diversity," he said.

The complete genetic road map of the African frog Xenopus tropicalis is published this week in the journal Science.

You May Like

Multimedia US Nurse ‘Cured of Ebola,’ NIH Says

Nina Pham, Texas nurse who treated first Ebola patient in US, received no experimental drugs; WHO expects vaccine surge in 2015 More

Video Islamic State Militants Encroach on Baghdad

Iraqi capital not under ‘imminent threat,’ US military says, amid worries about foothold More

Video Hong Kong Protesters Focus on Holding Volatile Mong Kok

Activists say holding Mong Kok is key to their movement's success, despite confrontations with angry residents and police More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
After Decades of Pressure, Luxembourg Drops Bank Secrecy Rulesi
X
October 21, 2014 12:20 AM
European Union finance ministers have reached a breakthrough agreement that will make it more difficult for tax cheats to hide their money. The new legislation, which had been blocked for years by countries with a reputation as tax havens, was approved last week after Luxembourg and Austria agreed to lift their vetoes. But as Mil Arcega reports, it doesn’t mean tax cheats have run out of places to keep their money hidden.
Video

Video After Decades of Pressure, Luxembourg Drops Bank Secrecy Rules

European Union finance ministers have reached a breakthrough agreement that will make it more difficult for tax cheats to hide their money. The new legislation, which had been blocked for years by countries with a reputation as tax havens, was approved last week after Luxembourg and Austria agreed to lift their vetoes. But as Mil Arcega reports, it doesn’t mean tax cheats have run out of places to keep their money hidden.
Video

Video Kobani Refugees Welcome, Turkey Criticizes, US Airdrop

Residents of Kobani in northern Syria have welcomed the airdrop of weapons, ammunition and medicine to Kurdish militia who are resisting the seizure of their city by Islamic State militants. The Turkish government, however, has criticized the operation. VOA’s Scott Bobb reports from southeastern Turkey, across the border from Kobani.
Video

Video China Political Meeting Seeks to Improve Rule of Law

China’s communist leaders will host a top level political meeting this week, called the Fourth Plenum, and for the first time in the party’s history, rule of law will be a key item on the agenda. Analysts and Chinese media reports say the meetings could see the approval of long-awaited measures aimed at giving courts more independence and include steps to enhance an already aggressive and high-reaching anti-corruption drive. VOA’s Bill Ide has more from Beijing.
Video

Video US ‘Death Cafes’ Put Focus on the Finale

In contemporary America, death usually is a topic to be avoided. But the growing “death café” movement encourages people to discuss their fears and desires about their final moments. VOA’s Jerome Socolovsky reports.
Video

Video Ebola Orphanage Opens in Sierra Leone

Sierra Leone's first Ebola orphanage has opened in the Kailahun district. Hundreds of children orphaned since the beginning of the Ebola outbreak face stigma and rejection with nobody to care for them. Adam Bailes reports for VOA about a new interim care center that's aimed at helping the growing number of children affected by Ebola.
Video

Video Young Nairobi Tech Innovator on 'Track' in Security Business

A 24-year-old technology innovator in Nairobi has invented a tracking device that monitors and secures cars. He has also come up with what he claims is the most robust audio-visual surveillance system yet. As Lenny Ruvaga reports from the Kenyan capital, his innovations are offering alternative security solutions.
Video

Video Latinas Converting to Islam for Identity, Structure

Latinos are one of the fastest growing groups in the Muslim religion. According to the Pew Research Center, about 6 percent of American Muslims are Latino. And a little more than half of new converts are female. VOA’s Carolyn Presutti travelled to Miami, Florida -- where two out of every three residents is Hispanic -- to learn more.
Video

Video Exclusive: American Joins Kurds' Anti-IS Fight

The United States and other Western nations have expressed alarm about their citizens joining Islamic State forces in Syria and Iraq. In a rare counterpoint to the phenomenon, an American has taken up arms with the militants' Syrian Kurdish opponents. Elizabeth Arrott has more in this exclusive profile by VOA Kurdish reporter Zana Omer in Ras al Ayn, Syria.
Video

Video South Korea Confronts Violence Within Military Ranks

Every able-bodied South Korean male between 18 and 35 must serve for 21 to 36 months in the country’s armed forces, depending upon the specific branch. For many, service is a rite of passage to manhood. But there are growing concerns that bullying and violence come along with the tradition. Reporter Jason Strother has more from Seoul.
Video

Video North Carolina Emerges as Key Election Battleground

U.S. congressional midterm elections will be held on November 4th and most political analysts give Republicans an excellent chance to win a majority in the U.S. Senate, which Democrats now control. So what are the issues driving voters in this congressional election year? VOA National Correspondent Jim Malone traveled to North Carolina, one of the most politically competitive states in the country, to find out.
Video

Video Comanche People Maintain Pride in Their Heritage

The Comanche (Indian nation) once were called the “Lords of the Plains,” with an empire that included half the land area of current day Texas, large parts of Oklahoma, New Mexico, Kansas and Colorado.The fierceness and battle prowess of these warriors on horseback delayed the settlement of most of West Texas for four decades. VOA’s Greg Flakus reports from Lawton, Oklahoma, that while their warrior days are over, the 15,000 members of the Comanche Nation remain a proud people.
Video

Video Turkey Campus Attacks Raise Islamic Radicalization Fears

Concerns are growing in Turkey of Islamic radicalization at some universities, after clashes between supporters of the jihadist group Islamic State (IS) or ISIS, and those opposed to the extremists. Pro-jihadist literature is on sale openly on the streets of Istanbul. Critics accuse the government of turning a blind eye to radicalism at home, while Kurds accuse the president of supporting IS - a charge strongly denied. Henry Ridgwell reports from London.

All About America

AppleAndroid