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

    How Aleppo Rebels Plan to Withstand Assad's Siege

    Rebels in Aleppo are laying plans to withstand a siege by Syrian President Bashar al-Assad’s forces in likelihood the regime cuts a final main supply line running west of city

    Probe Targeting China's Statistic Head Sparks Concern

    Economists now asking what prompted government to launch an investigation only months after Wang Baoan had been vetted for crucial job

    HRW: Both Sides in Ukraine Conflict Targeted, Used Schools

    Rights group documents how both sides in Ukraine conflict carried out attacks on schools and used them for military purposes

    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.
    Russia's Car Sales Shrink Overall, But Luxury and Economy Models See Growthi
    X
    February 10, 2016 5:54 AM
    Car sales in Russia dropped by more than a third in 2015 because of the country's economic woes. But, at the extreme ends of the car market, luxury vehicles and some economy brands are actually experiencing growth. VOA's Daniel Schearf reports from Moscow.
    Video

    Video Russia's Car Sales Shrink Overall, But Luxury and Economy Models See Growth

    Car sales in Russia dropped by more than a third in 2015 because of the country's economic woes. But, at the extreme ends of the car market, luxury vehicles and some economy brands are actually experiencing growth. VOA's Daniel Schearf reports from Moscow.
    Video

    Video Civil Rights Pioneer Remembers Struggle for Voting Rights

    February is Black History Month in the United States. The annual, month-long national observance pays tribute to important people and events that shaped the history of African Americans. VOA's Chris Simkins reports how one man fought against discrimination to help millions of blacks obtain the right to vote
    Video

    Video Jordanian Theater Group Stages Anti-Terrorism Message

    The lure of the self-styled “Islamic State” has many parents worried about their children who may be susceptible to the organization’s online propaganda. Dozens of Muslim communities in the Middle East are fighting back -- giving young adults alternatives to violence. One group in Jordan is using dramatic expression a send a family message. Mideast Broadcasting Network correspondent Haider Al Abdali shared this report with VOA. It’s narrated by Bronwyn Benito
    Video

    Video Migrant Crisis Fuels Debate Over Britain’s Future in EU

    The migrant crisis in Europe is fueling the debate in Britain ahead of a referendum on staying in the European Union that may be held this year. Prime Minister David Cameron warns that leaving the EU could lead to thousands more migrants arriving in the country. Meanwhile, tension is rising in Calais, France, where thousands of migrants are living in squalid camps. VOA's Henry Ridgwell reports.
    Video

    Video Valentine's Day Stinks for Lebanese Clowns

    This weekend, on Valentine's Day in Lebanon, love is not the only thing in the air. More than half a year after the country's trash crisis began, the stink of uncollected garbage remains on the streets. Step forward "Clown Me In," a group of clowns who use their skills for activism. Before the most romantic day of the year the clowns have released their unusual take on love in Lebanon -- in a bid to keep the pressure up and get the trash off the streets. John Owens reports from Beirut.
    Video

    Video Families Flee Aleppo for Kurdish Regions in Syria

    Not all who flee the fighting in Aleppo are trying to cross the border into Turkey. A VOA reporter caught up with several families heading for Kurdish-held areas of northern Syria.
    Video

    Video Rocky Year Ahead for Nigeria Amid Oil Price Crash

    The global fall in the price of oil has rattled the economies of many petroleum exporters, and Africa’s oil king Nigeria is no exception. As Chris Stein reports from Lagos, analysts are predicting a rough year ahead for the continent’s top producer of crude.
    Video

    Video 'No Means No' Program Targets Sexual Violence in Kenya

    The organizers of an initiative to reduce and stop rape in the informal settlements around Kenya's capital say their program is having marked success. Girls are taking self-defense classes while the boys are learning how to protect the girls and respect them. Lenny Ruvaga reports from Nairobi.
    Video

    Video Chocolate Lovers Get a Sweet History Lesson

    Observed in many countries around the world, Valentine’s Day is sometimes celebrated with chocolate festivals. But at a festival near Washington, the visitors experience a bit more than a sugar rush. They go on a sweet journey through history. VOA’s June Soh takes us to the festival.
    Video

    Video 'Smart' Bandages Could Heal Wounds More Quickly

    Simple bandages are usually seen as the first line of attack in healing small to moderate wounds and burns. But scientists say new synthetic materials with embedded microsensors could turn bandages into a much more valuable tool for emergency physicians. VOA’s George Putic reports.
    Video

    Video Researchers Use 3-D Printer to Produce Transplantable Body Parts

    Human organ transplants have become fairly common around the world in the past few decades. Researchers at various universities are coordinating their efforts to find solutions -- including teams at the University of Pennsylvania and Rice University in Houston that are experimenting with a 3-D printer -- to make blood vessels and other structures for implant. As VOA’s Greg Flakus reports from Houston, they are also using these artificial body parts to seek ways of defeating cancerous tumors.
    Video

    Video Helping the Blind 'See' Great Art

    There are 285 million blind and visually impaired people in the world who are unable to enjoy visual art at a museum. One New York photographer is trying to fix this situation by making tangible copies of the world’s masterpieces. VOA correspondent Victoria Kupchinetsky was there as visually impaired people got a feel for great art. Joy Wagner narrates her report.
    Video

    Video German Artists to Memorialize Refugees With Life Jacket Exhibit

    Sold in every kind of shop in some Turkish port towns, life jackets have become a symbol of the refugee crisis that brought a million people to Europe in 2015.  On the shores of Lesbos, Greece, German artists collect discarded life jackets as they prepare an art installation they plan to display in Germany.  For VOA, Hamada Elrasam has this report from Lesbos, Greece.
    Video

    Video E-readers Help Ease Africa's Book Shortage

    Millions of people in Africa can't read, and there's a chronic shortage of books. A non-profit organization called Worldreader is trying to help change all that one e-reader at a time. VOA’s Deborah Block tells us about a girls' school in Nairobi, Kenya where Worldreader is making a difference.