Oh Yeah, Developmental Biology!

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Posts tagged with "Evolution"

Dinosaurs, Fruit Flies, and Us

lcresearchcenter:

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July 26th, 2013

There have been revolutionary advances in our knowledge of genetics in the past 30 years. This is particularly true in a field of endeavor called developmental genetics, which strives to understand how genes work to put us together. To make a baby that grows and eventually makes its own babies.

We have found that genes which coordinate development in the fruit fly are similar in structure, function, expression, and genomic organization to genes in human beings (i.e., how they are arranged on chromosomes, what regulates them and how they interact with each other). Yet fruit flies are not like us: among other obvious differences they have wings and we don’t (even if we wish we did!).

The formation of wings or legs or a segmented abdomen or hundreds of other steps are all part of a genetically specified developmental program leading to a body plan, a process which is called pattern formation. The revolution in part is the understanding of the degree of conservation of the genes responsible across huge phylogenetic chasms. In other words the degree to which the genes are the same even though we evolved into different animals almost a hundred million years ago.

Read More

What the smallest infectious agents reveal about evolution

on-the-origin-of-species:

Impressive proof of evolution and a summary of what evolution is, whether in the short or long term. A great read.

Top 10: Dinosaur Myths

jtotheizzoe:

Belief is for ghost stories and R. Kelly songs about flying.
We go for testable hypotheses followed by careful observation, data collection and refinement of said hypothesis based on our current level of ignorance/knowledge on the subject at hand around these here parts. Now let’s talk about that grammar and use of two different fonts …
(source unknown)

jtotheizzoe:

Belief is for ghost stories and R. Kelly songs about flying.

We go for testable hypotheses followed by careful observation, data collection and refinement of said hypothesis based on our current level of ignorance/knowledge on the subject at hand around these here parts. Now let’s talk about that grammar and use of two different fonts …

(source unknown)

Research Suggests How Fins Became Legs

sciencebriefs:

Vertebrates’ transition to living on land, instead of only in water, represented a major event in the history of life. Now, researchers provide new evidence that the development of hands and feet occurred through the gain of new DNA elements that activate particular genes.

In order to understand how fins may have evolved into limbs, researchers led by José Luis Gómez-Skarmeta and Fernando Casares introduced extra Hoxd13, a gene known to play a role in distinguishing body parts, at the tip of a zebrafish embryo’s fin. Surprisingly, this led to the generation of new cartilage tissue and the reduction of fin tissue – changes that strikingly recapitulate key aspects of land-animal limb development. The researchers wondered whether novel Hoxd13 control elements may have increased Hoxd13 gene expression in the past to cause similar effects during limb evolution. They turned to a DNA control element that is known to regulate the activation of Hoxd13 in mouse embryonic limbs and that is absent in fish.

“We found that in the zebrafish, the mouse Hoxd13 control element was capable of driving gene expression in the distal fin rudiment. This result indicates that molecular machinery capable of activating this control element was also present in the last common ancestor of finned and legged animals and is proven by its remnants in zebrafish,” Casares said.

More:

Fins to limbs with flip of genetic switch
They came from the sea: the gene behind limb evolution
Zebrafish made to grow pre-hands instead of fins
Turning Fins Into Hands

Turing model for embryonic development of fingers and toes confirmed

sciencebriefs:

Scientists have identified the mechanism responsible for generating our fingers and toes, and revealed the importance of gene regulation in the transition of fins to limbs during evolution. By combining genetic studies with mathematical modeling, the scientists provided experimental evidence supporting a theoretical model for pattern formation known as the Turing mechanism. In 1952, mathematician Alan Turing proposed mathematical equations for pattern formation, which describes how two uniformly-distributed substances, an activator and a repressor, trigger the formation of complex shapes and structures from initially-equivalent cells.

“The Turing model for pattern formation has long been debated, mostly due to the lack of experimental data supporting it,” explained Rushikesh Sheth, co-first author of the study. “By studying the role of Hox genes during limb development, we were able to show, for the first time, that the patterning process that generates our fingers and toes relies on a Turing-like mechanism.”

In humans, as in other mammals, the embryo’s development is controlled, in part, by Hox genes. These genes are essential to the proper positioning of the body’s architecture, and define the nature and function of cells that form organs and skeletal elements.

“Our genetic study suggested that Hox genes act as modulators of a Turing-like mechanism, which was further supported by mathematical tests,” added Marie Kmita, one of the team leaders. “Moreover, we showed that drastically reducing the dose of Hox genes in mice transforms fingers into structures reminiscent of the extremities of fish fins. These findings further support the key role of Hox genes in the transition of fins to limbs during evolution, one of the most important anatomical innovations associated with the transition from aquatic to terrestrial life.”

I have a special place in my heart for all things Turing as he was the subject of my final year dissertation. 

neurosciencestuff:

Paddlefish’s doubled genome may question theories on limb evolution
The American paddlefish — known for its bizarre, protruding snout and eggs harvested for caviar — duplicated its entire genome about 42 million years ago, according to a new study published in the journal Genome Biology and Evolution. This finding may add a new twist to the way scientists study how fins evolved into limbs since the paddlefish is often used as a proxy for a more representative ancestor shared by humans and fishes.
“We found that paddlefish have had their own genome duplication,” said Karen Crow, assistant professor of biology at San Francisco State University. “This creates extra genetic material that adds complexity to comparative studies. It may change the way we interpret studies on limb development.”
In order to study how human limbs develop, scientists compare the limb-building genes found in mice with fin-building genes found in fishes. Previous research on paddlefish has suggested that fishes possessed the genetic toolkit required to grow limbs long before the evolution of the four-limbed creatures (tetrapods) that developed into reptiles, birds, amphibians and mammals.
In the last decade, paddlefish have become a useful benchmark in evolutionary studies because their position on the evolutionary tree makes them a reasonably good proxy for the ancestor of the bony fishes that evolved into tetrapods such as humans. However, the fact that paddlefish underwent a genome duplication could complicate what its genes tell us about the fin-to-limb transition, says Crow.

neurosciencestuff:

Paddlefish’s doubled genome may question theories on limb evolution

The American paddlefish — known for its bizarre, protruding snout and eggs harvested for caviar — duplicated its entire genome about 42 million years ago, according to a new study published in the journal Genome Biology and Evolution. This finding may add a new twist to the way scientists study how fins evolved into limbs since the paddlefish is often used as a proxy for a more representative ancestor shared by humans and fishes.

“We found that paddlefish have had their own genome duplication,” said Karen Crow, assistant professor of biology at San Francisco State University. “This creates extra genetic material that adds complexity to comparative studies. It may change the way we interpret studies on limb development.”

In order to study how human limbs develop, scientists compare the limb-building genes found in mice with fin-building genes found in fishes. Previous research on paddlefish has suggested that fishes possessed the genetic toolkit required to grow limbs long before the evolution of the four-limbed creatures (tetrapods) that developed into reptiles, birds, amphibians and mammals.

In the last decade, paddlefish have become a useful benchmark in evolutionary studies because their position on the evolutionary tree makes them a reasonably good proxy for the ancestor of the bony fishes that evolved into tetrapods such as humans. However, the fact that paddlefish underwent a genome duplication could complicate what its genes tell us about the fin-to-limb transition, says Crow.

More sophisticated wiring, not just a bigger brain, helped humans evolve beyond chimps

fuckyeahneuroscience:

from UCLA Newsroom:

Human and chimp brains look anatomically similar because both evolved from the same ancestor millions of years ago. But where does the chimp brain end and the human brain begin? 
A new UCLA study pinpoints uniquely human patterns of gene activity in the brain that could shed light on how we evolved differently than our closest relative. The identification of these genes could improve understanding of human brain diseases like autism and schizophrenia, as well as learning disorders and addictions.
The research appears Aug. 22 in the advance online edition of the journal Neuron.
“Scientists usually describe evolution in terms of the human brain growing bigger and adding new regions,” said principal investigator Dr. Daniel Geschwind, the Gordon and Virginia MacDonald Distinguished Professor of Human Genetics and a professor of neurology at the David Geffen School of Medicine at UCLA. “Our research suggests that it’s not only size but the rising complexity within brain centers that led humans to evolve into their own species.”
Full paper in Neuron here. For free, if I’m not mistaken!
Feb 5

Clint Eastwood helps reveal secrets of brain evolution

Clint Eastwood might sound like an unlikely candidate to help investigate the evolution of the brain, but he has lent a helping hand to researchers doing just that. It turns out that brain regions that do the same job in monkeys and humans aren’t always found in the same part of the skull.

Previous studies comparing brains across species tended to assume that human brains were just blown-up versions of monkey brains and that functions are carried out by anatomically similar areas.

To test this idea, Wim Vanduffel of Harvard Medical School in Boston and the Catholic University of Leuven (KUL) in Belgium, and colleagues scanned the brains of 24 people and four rhesus monkeys while they watched The Good, The Bad and The Ugly. They compared the brain responses of each individual to the same sensory stimulation, and identified which brain areas had similar functions.

The majority of the human and monkey brain maps lined up, but some areas with a similar function were in completely different places.

The team say the discovery is crucial to building more accurate models of our evolution. “You can’t assume that because A and B are close together in the monkey brain, they need to be close together in the human brain,” Vanduffel says.

Feb 3
allthingsentropy:

Common ancestors

allthingsentropy:

Common ancestors