Posts tagged neuroscience
Articles and news from the latest research reports.
What Is the Human Genome?
The human genome that researchers sequenced at the turn of the century doesn’t really exist as we know it.
The Human Genome project sequenced “the human genome” and is widely credited with setting in motion the most exciting era of fundamental new scientific discovery since Galileo. That’s remarkable, because in important ways “the human genome” that we have labeled as such doesn’t actually exist.
cosmin4000, istockphoto
Plato essentially asserted that things like chairs and dogs, which we observe in this physical world, and even concepts like virtues, are but imperfect representations or instances of some ideal that exists, but not in the material world. Such a Platonic ideal is “the human genome,” a sequence of about 3 billion nucleotides arrayed across a linear scale of position from the start of chromosome 1 to the end of the sex chromosomes. Whether it was obtained from one person or several has so far been shrouded in secrecy for bioethical reasons, but it makes no real difference. What we call the human genome sequence is really just a reference: it cannot account for all the variability that exists in the species, just like no single dog on earth, real or imagined, can fully incorporate all the variability in the characteristics of dogs.
Nor is the human genome we have a “’normal” genome. What would it mean to be “normal” for the nucleotide at position 1,234,547 on chromosome 11? All we know is that the donor(s) had no identified disease when bled for the cause, but sooner or later some disease will arise. Essentially all available whole genome sequences show potentially disease-producing variants, even including nonfunctional genes, in donors who were unaffected at the time.
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.
MRI of human skull (sagittal view)
Brazilian construction worker has a lucky escape after a 1.8m-long iron bar fell from a building through his head.
A builder is recovering after an operation to remove a 1.8m-long iron bar from his head. The bar fell from the fifth floor of a building under construction, went through Eduardo Leite’s hard hat, pierced the back of his skull and exited between his eyes. Amazingly the 24-year-old survived and when he arrived at hospital he was conscious and able to tell doctors what had happened.
(Source: Guardian)
What is it that makes the human brain so special? Sure it’s big — but it’s far from the biggest brain around. You’ve heard that your brain contains 100 billion neurons — but where does that number really come from, and how does it stack up against other species?
Here are four of neuroscience’s biggest brain myths
Face off: Disney scientists reveal technique to ‘clone’ a human face onto an animatronic head
Disney has revealed its scientists have perfected how to recreate a human face on a robot head.
The team at Disney’s Zurich research lab say the breakthrough could lead to a new generation of digital animatronic characters far more lifelike than those currently seen in its theme parks.
'We propose a complete process for designing, simulating and fabricating synthetic skin for an animatronics character that mimics the face of a given subject and expressions', Disney said in a researcher paper.
HOW IT WORKS:
- The multi-step process begins with a three-dimensional scan to capture every detail of the actor’s face.
- Measurements that catalog minute details such as facial hairs are taken and entered into a virtual rendering of the actor’s face.
- Scientists then take the image from virtual to physical, using a carefully developed synthetic skin made of silicone placed on an animatronic head to complete the model.
- During their experiments, researchers let the completed head sit for seven days at room temperature before installing the complex robotics inside.
The human microbiome: Me, myself, us
Looking at human beings as ecosystems that contain many collaborating and competing species could change the practice of medicine.
A human being is an individual who has grown from a fertilised egg which contained genes from both father and mother. A growing band of biologists, however, think this definition incomplete. They see people not just as individuals, but also as ecosystems. In their view, the descendant of the fertilised egg is merely one component of the system. The others are trillions of bacteria, each equally an individual, which are found in a person’s gut, his mouth, his scalp, his skin and all of the crevices and orifices that subtend from his body’s surface.
A healthy adult human harbours some 100 trillion bacteria in his gut alone. That is ten times as many bacterial cells as he has cells descended from the sperm and egg of his parents. These bugs, moreover, are diverse. Egg and sperm provide about 23,000 different genes. The microbiome, as the body’s commensal bacteria are collectively known, is reckoned to have around 3m. Admittedly, many of those millions are variations on common themes, but equally many are not, and even the number of those that are adds something to the body’s genetic mix.
Scientists have cracked a molecular code that may open the way to destroying or correcting defective gene products, such as those that cause genetic disorders in humans.
The code determines the recognition of RNA molecules by a superfamily of RNA-binding proteins called pentatricopeptide repeat (PPR) proteins.
When a gene is switched on, it is copied into RNA. This RNA is then used to make proteins that are required by the organism for all of its vital functions. If a gene is defective, its RNA copy and the proteins made from this will also be defective. This forms the basis of many terrible genetic disorders in humans.
RNA-binding PPR proteins could revolutionise the way we treat disease. Their secret is their versatility - they can find and bind a specific RNA molecule, and have the capacity to correct it if it is defective, or destroy it if it is detrimental. They can also help ramp up production of proteins required for growth and development.
The new paper in PLOS Genetics describes for the first time how PPR proteins recognise their RNA targets via an easy-to-understand code. This mechanism mimics the simplicity and predictability of the pairing between DNA strands described by Watson and Crick 60 years ago, but at a protein/RNA interface.