Songbird’s DNA may shed light on human speech. The zebra finch, a chatty little songbird that learns his speech from his father and passes it on to his offspring, has long been a model for scientists studying human speech disorders. Now an international team of researchers has sequenced the zebra finch’s entire genome, hoping the secrets of the Australian bird’s genes will lead to advances in understanding human speech and learning disorders in problems as varied as autism, strokes, the late stages of Parkinson’s disease and even stuttering. After five years of laborious analysis, the full assortment of the finch’s genes is reported today in the journal Nature by scientists who say they have decoded 800 genes involved in the finch’s ability to learn his father’s songs. Allison J. Doupe, who is a psychiatrist and a neuroscientist at UCSF, said sequencing the genome of the finch opens up new opportunities to study human disorders involving the nervous system because many of the finch’s genes are apparently identical to those in humans. “Once you know that whole genome, you have a list of the parts in the brain concerned with vocal learning,” said Doupe, who was not a member of the sequencing team. “It’s amazing how many of the finch’s behavioral patterns are like humans, and how many of their genes are also found in the human genome.” Only 4 inches long and weighing less than half an ounce, the zebra finch has a stubby, bright
orange beak, black-and-white-striped feathers on its throat and an orange and white mottled breast. Only the males sing. Like many birds, male and female zebra finches mate for life. But the zebra finches are unique because they seem to merely babble when they’re very young. It’s only as they grow that they learn their songs note by note from their fathers. As adults, they pass those same songs on to their male offspring, with only minor variations. And so it goes, from generation to generation. The sequencing team of more than 80 scientists was led by Wesley C. Warren of Washington University in St. Louis and David F. Clayton of the University of Illinois. “We hope that the zebra finch will be a model for us to study what’s going on at the molecular level in the brain,” Clayton said in an interview. The bird’s entire genome holds roughly a billion units of DNA that carry the code for making proteins – about half the number in the human genome. But one surprise in analyzing its genes, Clayton said, was that the team also discovered large numbers of “noncoding” RNA molecules that apparently influence hundreds of genes to turn on or off as the birds learn to sing. “It’s an unexpected finding that we still don’t fully understand,” he said. news from sfgate.com ~ The Zebra Finch, Taeniopygia guttata, is the most common and familiar estrildid finch of Central Australia and ranges over most of the continent, avoiding only the cool moist south and the tropical far north. It also can be found natively in Indonesia and Timor-Leste. The bird has been introduced to Puerto Rico, Portugal and the U.S..The ground-dwelling Zebra Finch grows to a size of about 10 centimetres (3.9 in)
long and prefers to eat grass seeds.This species’ vocalizations consist mostly of chattering trills and calls. Zebra Finches inhabit a wide range of grasslands and forests, usually close to water.They are typically found in open steppes with scattered bushes and trees, but have adapted to human disturbances, taking advantage of human-made watering holes and large patches of deforested land. Zebra Finches — including many human-bred variants to the species — are widely kept by genetic researchers, breeding hobbyists and pet owners.The Zebra Finch breeds after substantial rains in its native habitat, which can occur at any time of the year. Birds in captivity are ready to breed year-round. Wild birds are adaptable and varied in their nesting habits, with nests being found in cavities, scrub, low trees, bushes, on the ground, in termite hills, rabbit burrows, nests of other birds, and in the cracks, crevices, and ledges of human structures. Outside of the breeding time, brood nests are constructed for sleeping in. The life expectancy of a Zebra Finch is highly variable because of genetic and environmental factors. The Zebra Finch may reach up to 15 years in its natural environment, averaging 5 to 10 years in captivity.The greatest threat to the survival of the species are cats and loss of natural food. Zebra Finches are loud and boisterous singers. Their call can be a loud “beep”, “meep”, “oi!” or “a-ha!”, sounding something like a toy trumpet or the buttons on a phone being pushed. Their song is a few small beeps, leading up to a rhythmic song of varying complexity in males. Each male’s song is different, although birds of the same bloodline will exhibit similarities, and all finches will overlay their own uniqueness onto a common rhythmic framework. Fathers pass on their songs to their sons
with little variation. Songs may change during puberty, but afterwards they are locked in for the life of the bird.Scientific research at Japan’s RIKEN institute has suggested that singing to females is an emotionally rewarding experience for male Zebra Finches. Male Zebra Finches begin to sing at puberty while females lack a singing ability.This is due to a developmental difference, where in the embryo, the male Zebra Finch produces estrogen, which is transformed into a testosterone-like hormone in the brain, which in turn leads to the nervous development of a song system. Their song begins as a few disjointed sounds, but as they experiment and match what they sing to the memory of the father’s song, it rapidly matures into a full-fledged song. During these formative times, they will incorporate sounds from their surroundings into their song, also using the songs of other nearby males for inspiration. Male finches use their song, in part, as a mating call. The mating act is usually accompanied by a high pitched whining sound. They will also exhibit a hissing sound when they are protecting their territory. Because Zebra Finch males learn their songs, they are often used as avian model organisms to investigate the neural bases of learning, memory, and sensorimotor integration. The Zebra Finch genome was the second bird genome to be sequenced, in 2008, after chicken. Their popularity as model organisms is also related to their prolific breeding, an adaptation to their usually dry environment. This ability also makes them popular as pet songbirds. ~ GoodNews International Edition
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