New evolutionary insights into the early development of songbirds

DECEMBER 2, 2019

by Uppsala University

An international team led by Alexander Suh at Uppsala University has sequenced a chromosome in zebra finches called the germline-restricted chromosome (GRC). This chromosome is only found in germline cells, the cells that hold genetic information which is passed on to the next generation. The researchers found that the GRC is tens of millions of years old and plays a key role in songbird biology, having collected genes used for embryonic development.

The ability to reproduce is a fundamental trait of all life. How reproduction has evolved and how it functions on a genetic level is therefore of great interest to evolutionary biologists. During the early development of an animal embryo, cells are divided into two major types, germline and somatic cells. Germline cells are present in the reproductive organs and hold genetic information which is passed on to the next generation, whereas somatic cells are the cells which make up the rest of the organism. Biologists have discovered that in some organisms, certain genes and repetitive DNA-sequences are eliminated when cells become either somatic or germline, which means that not all cells in an organism contain the same genome.

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Songbirds sing species-specific songs

NOVEMBER 12, 2019

The generation of species-specific singing in songbirds is associated with species-specific patterns of gene activity in brain regions called song nuclei, according to a study published November 12 in the open-access journal PLOS Biology by Kazuhiro Wada of Hokkaido University in Japan, and colleagues. According to the authors, the findings could be a promising step toward a better understanding of the contribution of multiple genes to the evolution of behaviors.

Learning of most complex motor skills, such as birdsong and human speech, is constrained in a manner that is characteristic of each species, but the mechanisms underlying species-specific learned behaviors remain poorly understood. Songbirds acquire species-specific songs through learning, which is also thought to depend on species-specific patterns of gene activity in song nuclei—brain regions known to be specialized for vocal learning and production.

In the new study, Wada and colleagues made use of two closely related songbird species—the zebra finch (Taeniopygia guttata) and the owl finch (Taeniopygia bichenovii)—and also the hybrid offspring of matings between these two species. This allowed them to examine the relationship between inter-species differences in gene expression and the production of species-specific song patterns.

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Researchers Implant Memories in Zebra Finch Brains

Juvenile birds learn the length of the sounds in a song from a false memory introduced via optogenetics, instead of from real interactions with a tutor bird.

Oct 3, 2019
ABBY OLENA

Animals learn by imitating behaviors, such as when a baby mimics her mother’s speaking voice or a young male zebra finch copies the mating song of an older male tutor, often his father. In a study published today in Science, researchers identified the neural circuit that a finch uses to learn the duration of the syllables of a song and then manipulated this pathway with optogenetics to create a false memory that juvenile birds used to develop their courtship song.

“In order to learn from observation, you have to create a memory of someone doing something right and then use this sensory information to guide your motor system to learn to perform the behavior. We really don’t know where and how these memories are formed,” says Dina Lipkind, a biologist at York College who did not participate in the study. The authors “addressed the first step of the process, which is how you form the memory that will later guide [you] towards performing this behavior.”

“Our original goals were actually much more modest,” says Todd Roberts, a neuroscientist at UT Southwestern Medical Center. Initially, Wenchan Zhao, a graduate student in his lab, set out to test whether or not disrupting neural activity while a young finch interacted with a tutor could block the bird’s ability to form a memory of the interchange. She used light to manipulate cells genetically engineered to be sensitive to illumination in a brain circuit previously implicated in song learning in juvenile birds.

Zhao turned the cells on by shining a light into the birds’ brains while they spent time with their tutors and, as a control experiment, when the birds were alone. Then she noticed that the songs that the so-called control birds developed were unusual—different from the songs of birds that had never met a tutor but also unlike the songs of those that interacted with an older bird.




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Rapid response for inflammation control in songbirds' brains could lead to therapies in humans

Date: March 14, 2016

Source: American University

A biological process in the brains of zebra finches shows that the songbirds respond quickly to trauma and are capable of controlling the natural inflammation that occurs to protect the brain from injury.

Understanding the process well enough could lead to therapies in humans to control inflammation and hasten recovery from brain injury such as stroke, said American University Prof. Colin Saldanha, whose study "Centrally Synthesized Estradiol is a Potent Anti-Inflammatory in the Injured Zebra Finch Brain" has published in Endocrinology here. Through experiments, Saldanha and his colleagues found that estrogen-producing glial cells play a role in the rapid response.

"The most surprising thing to me is that the inflammation control is happening within hours, and that estrogen is made in the brain around an injury site in response to an injury," Saldanha said. "These animals have evolved a mechanism to protect their brains from injury very quickly."

Preserving brain function

Inflammation is a normal part of the body's immune response. It affects the brain differently compared with other parts of the body. In the brain, too much inflammation can cause degenerative effects, or in the worst case scenario, death. Chronic inflammation causes cell damage and the loss of important neurons that regulate memory, mood and movement. Being able to control and limit inflammation in an injured brain may preserve vital brain function.

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Roots of Language in Human and Bird Biology: Genes Activated for Human Speech Similar to Ones Used by Singing Songbirds

Feb. 14, 2013 — The genes activated for human speech are similar to the ones used by singing songbirds, new experiments suggest.

These results, which are not yet published, show that gene products produced for speech in the cortical and basal ganglia regions of the human brain correspond to similar molecules in the vocal communication areas of the brains of zebra finches and budgerigars. But these molecules aren't found in the brains of doves and quails -- vocal birds that do not learn their sounds.

Zebra finch (Wikipedia)

"The results suggest that similar behavior and neural connectivity for a convergent complex trait like speech and song are associated with many similar genetic changes," said Duke neurobiologist Erich Jarvis, a Howard Hughes Medical Institute investigator.

Jarvis studies the molecular pathways that songbirds use while learning to sing. In past experiments, he and his collaborators found that songbirds have a connection between the front part of their brain and nerves in the brainstem that control movement in muscles that make songs in birds. They've seen this circuit in a more primitive form related to ultrasonic mating calls in mice. Humans also have this motor learning pathway for speech.

Continued:  http://www.sciencedaily.com/releases/2013/02/130214111604.htm