Posts tagged science
Articles and news from the latest research reports.
Biologists try to engineer life that can survive on Mars and aid colonisation
With Nasa’s Curiosity Rover safely on Mars and ready to search for signs of life, back on Earth attempts are underway to engineer bacteria that could thrive on the Red Planet.
A team of undergraduates from Stanford and Brown Universities are busy applying synthetic biology to space exploration, outfitting microbes to survive extreme Martian conditions and produce resources needed to sustain a human colony.
Though Mars is potentially a place where life may have survived at some point, it is not an especially friendly environment, and thriving there will not be easy — for humans or microbes. The average surface temperature of Mars is minus 80 degrees Fahrenheit, and the almost-nonexistent atmosphere is 95 percent carbon dioxide. Although water exists in Mars’ ice caps and there’s some evidence that giant oceans once covered the planet, today it’s essentially a deep-frozen desert. Colonising Mars would be challenging and pricey.
'Selfish' DNA in animal mitochondria offers possible tool to study aging
Researchers at Oregon State University have discovered, for the first time in any animal species, a type of “selfish” mitochondrial DNA that is actually hurting the organism and lessening its chance to survive – and bears a strong similarity to some damage done to human cells as they age.
Such selfish mitochondrial DNA has been found before in plants, but not animals. In this case, the discovery was made almost by accident during some genetic research being done on a nematode, Caenorhabditis briggsae – a type of small roundworm.
“We weren’t even looking for this when we found it, at first we thought it must be a laboratory error,” said Dee Denver, an OSU associate professor of zoology. “Selfish DNA is not supposed to be found in animals. But it could turn out to be fairly important as a new genetic model to study the type of mitochondrial decay that is associated with human aging.”
Hormone in Fruit Flies Sheds Light On Diabetes Cure, Weight-Loss Drug for Humans
ScienceDaily (Aug. 9, 2012) — Manipulating a group of hormone-producing cells in the brain can control blood sugar levels in the body — a discovery that has dramatic potential for research into weight-loss drugs and diabetes treatment.
Erik Johnson uses the fruit fly, Drosophila, to look at an enzyme called AMP-activated kinase and its role in signaling the hormone that elevates the level of sugar in the blood. (Credit: Image courtesy of Wake Forest University)
In a paper published in the October issue of Genetics and available online now, neurobiologists at Wake Forest University examine how fruit flies (Drosophila) react when confronted with a decreased diet.
Reduced diet or starvation normally leads to hyperactivity in fruit flies — a hungry fly buzzes around feverishly, looking for more food. That happens because an enzyme called AMP-activated kinase stimulates the secretion of the adipokinetic hormone, which is the functional equivalent of glucagon. This hormone acts opposite of insulin, as it tells the body to release the sugar, or food, needed to fuel that hyperactivity. The body uses up its energy stores until it finds food.
But when Wake Forest’s Erik Johnson, an associate professor of biology, and his research team turned off AMP-activated kinase, the cells decreased sugar release and the hyperactive response stopped almost completely — even in the face of starvation.
"Since fruit flies and humans share 30 percent of the same genes and our brains are essentially wired the same way, it suggests that this discovery could inform metabolic research in general and diabetes research specifically," said Johnson, the study’s principal investigator. "The basic biophysical, biochemical makeup is the same. The difference in complexity is in the number of cells. Why flies are so simple is that they have approximately 100,000 neurons versus the approximately 11 billion in humans."
Medical advances as a result of this research might include:
• Diabetes research: Adipokinetic hormone is the insect equivalent to the hormone glucagon in the human pancreas. Glucagon raises blood sugar levels; insulin reduces them. However, it is difficult to study glucagon systems because the pancreatic cells are hard to pull apart. Studying how this similar system works in the fruit fly could pave the way to a drug that targets the cells that cause glucagon to tell the body to release sugar into the blood — thus reducing the need for insulin shots in diabetics.
• Weight-loss drugs: An “exercise drug” would turn on all AMP-activated kinase in the body and trick the body into thinking it was exercising. “Exercise stimulates AMP-activated kinase, so manipulation of this molecule may lead to getting the benefits of exercise without exercising,” Johnson said. In previous research published in the online journal PLoS ONE, Johnson and his colleagues found that, when you turn off AMP-activated kinase, you get fruit flies that “eat a lot more than normal flies, move around a lot less, and end up fatter.”
Source: Science Daily
Tracking Fruit Flies to Understand the Function of the Nervous System
Researchers at the Freie Universität Berlin, Germany and the Center for Genomic Regulation (CRG) in Barcelona, Spain have designed open source software that allows tracking the position of Drosophila fruit flies as well as their larvae during behavioral experiments.
Dr. Matthieu Louis, the head of the Spanish team explains: “Until we developed these tools, many researchers relied on expensive commercial hardware and software to study the behavior of larvae and adult flies. Now, virtually anybody can do this kind of research. The value of the software we are proposing is that they are written in a simple programming language, which facilitates their adaptation to new experimental paradigms” Inexpensive, ubiquitous digital cameras, such as webcams are sufficient to capture the movements of the animals and the open source software packages both for the evaluation the video feeds for tracking as well as for later data analysis are available for free (http://buridan.sourceforge.net).
"Apart from ruining your glass of expensive red wine, Drosophila is a central model organism to study, amongst other problems, how brains work. By carefully watching whether flies turn left or right, we aim at understanding how humans make decisions” explained Dr. Alejandro Gomez-Marin, first author in the Spanish team.
Electrical Brain Stimulation Curbs Epileptic Seizures in Rats
THURSDAY, Aug. 9 (HealthDay News) — Researchers report that they have created a device able to short-circuit epileptic seizures in rats.
Similar in design to an implantable defibrillator, the device is placed in the brain and reacts only when a seizure starts to occur, essentially aborting the seizure’s electrical activity.
The self-adjusting device electrically stimulates the brain at the beginning of a short but frequent type of seizure in rats, and then automatically shuts itself off. The research was published in the Aug. 10 issue of the journal Science.
"It works like a ping-pong game," explained study author Dr. Gyorgy Buzsaki, a professor of neural science at New York University. "Every time a ball is coming your way, you apply an interfering pattern to whack it away."
Epilepsy is a brain disorder in which a person has repeated seizures over time. It affects nearly 3 million Americans, according to the Epilepsy Foundation, making it the third most common neurological disorder in the United States, after Alzheimer’s and stroke.
People with epilepsy can suffer from two different kinds of seizures: petit mal seizures, which last for just a few seconds but can occur frequently, and grand mal seizures, which are rare but involve violent muscle contractions and a loss of consciousness.
Seizures are episodes of disturbed brain activity that cause changes in attention or behavior. Brain cells keep firing instead of acting in an organized way. The malfunctioning electrical system of the brain causes surges of energy that can cause unconsciousness and muscle contractions.
The researchers tested the new device against petit mal seizures in rats because this type of seizure occurs hundreds of times a day. The sheer volume of the seizures allowed the scientists to effectively test the system they designed. People with petit mal seizures are typically treated effectively with drugs, so the device would not be used to treat that type of seizure.
In what Buzsaki describes as a simple, closed-loop system, the firing of brain neurons creates a spike in neurological activity that is followed by a wave and detected by the device, which fires back only when necessary. The system, called transcranial electrical stimulation, leaves other aspects of brain function unaffected. “The system doesn’t prevent seizures, it just treats them right away,” said Buzsaki. The stimulation reduced the length of a seizure by about 60 percent.
In humans, two plates about the size of a pocket watch could be placed in the skull in a position designed to target the affected area of the brain. The electrodes would be powered by ultralight electrical circuits implanted in the skull, Buzsaki explained.
The goal is to apply the system that worked in rats to people with complex partial seizures — epileptic seizures that affect both sides of the brain and cause a loss of consciousness, Buzsaki said. Although the device worked in rats, the results may not translate to humans.
This type of seizure also can occur with head injuries, brain infection and stroke. The cause is typically unknown.
In 20 percent to 40 percent of people who have complex partial seizures, drugs are ineffective and there are no remedies, Buzsaki said. “It’s not clear what kind of stimulation to deliver and where exactly in the brain the stimulation should go,” he explained.
Dr. Orrin Devinsky, director of the epilepsy program at New York University, said the research has enormous potential for treating epilepsy and other neurological problems. “What’s unique about this technique is that it’s a sophisticated way to identify the rhythmicity of the seizure itself and interrupt the cycle with precision,” he said. “Existing [deep brain stimulation] devices don’t finesse the timing this way.”
Devinsky, who was not associated with the study, said the research could potentially be applicable to people with tremors, Parkinson’s disease and even those with serious depression and other psychological disorders.
Source: HealthDay
![Blood Test for Alzheimer’s Gaining Ground
Hu and his collaborators at the University of Pennsylvania and Washington University, St. Louis, measured the levels of 190 proteins in the blood of 600 study participants at those institutions. Study participants included healthy volunteers and those who had been diagnosed with Alzheimer’s disease or mild cognitive impairment (MCI). MCI, often considered a harbinger for Alzheimer’s disease, causes a slight but measurable decline in cognitive abilities.
A subset of the 190 protein levels (17) were significantly different in people with MCI or Alzheimer’s. When those markers were checked against data from 566 people participating in the multicenter Alzheimer’s Disease Neuroimaging Initiative, only four markers remained: apolipoprotein E, B-type natriuretic peptide, C-reactive protein and pancreatic polypeptide.
Changes in levels of these four proteins in blood also correlated with measurements from the same patients of the levels of proteins [beta-amyloid] in cerebrospinal fluid that previously have been connected with Alzheimer’s. The analysis grouped together people with MCI, who are at high risk of developing Alzheimer’s, and full Alzheimer’s.
“We were looking for a sensitive signal,” says Hu. “MCI has been hypothesized to be an early phase of AD, and sensitive markers that capture the physiological changes in both MCI and AD would be most helpful clinically.”](http://36.media.tumblr.com/tumblr_m8iugkqjaX1rog5d1o1_500.jpg)
Blood Test for Alzheimer’s Gaining Ground
Hu and his collaborators at the University of Pennsylvania and Washington University, St. Louis, measured the levels of 190 proteins in the blood of 600 study participants at those institutions. Study participants included healthy volunteers and those who had been diagnosed with Alzheimer’s disease or mild cognitive impairment (MCI). MCI, often considered a harbinger for Alzheimer’s disease, causes a slight but measurable decline in cognitive abilities.
A subset of the 190 protein levels (17) were significantly different in people with MCI or Alzheimer’s. When those markers were checked against data from 566 people participating in the multicenter Alzheimer’s Disease Neuroimaging Initiative, only four markers remained: apolipoprotein E, B-type natriuretic peptide, C-reactive protein and pancreatic polypeptide.
Changes in levels of these four proteins in blood also correlated with measurements from the same patients of the levels of proteins [beta-amyloid] in cerebrospinal fluid that previously have been connected with Alzheimer’s. The analysis grouped together people with MCI, who are at high risk of developing Alzheimer’s, and full Alzheimer’s.
“We were looking for a sensitive signal,” says Hu. “MCI has been hypothesized to be an early phase of AD, and sensitive markers that capture the physiological changes in both MCI and AD would be most helpful clinically.”
Mother loses 20 years of memory after fall
Kay Delaney, 55, slipped over at work and hit her head last year, suffering a minor traumatic brain injury which caused retrograde amnesia.
She is now convinced she is 34 years old, with her last memory being putting her young son and daughter to bed in the early 1990s.
Former home manager Kay said she is surprised every time she looks in the mirror at her aged face, and has no concept of the last two decades.
Saying she feels an “almost unbearable” sense of guilt after failing to remember the birth of her youngest son, now 20, she added she “cannot even begin to describe the pain and sense of loss” at being left “without a sense of motherhood”.
Mother-of-three Kay struggles to recognise mobile phones and computers, or even make a cup of tea because she repeatedly forgets to boil the kettle.
The sought-after equanimity of “living in the moment” may be impossible, according to neuroscientists who’ve pinpointed a brain area responsible for using past decisions and outcomes to guide future behavior. The study is the first of its kind to analyze signals associated with metacognition—a person’s ability to monitor and control cognition (a term cleverly described by researchers as “thinking about thinking.”
Why aren’t our thoughts independent of each other? Why don’t we just live in the moment? For a healthy person, it’s impossible to live in the moment. It’s a nice thing to say in terms of seizing the day and enjoying life, but our inner lives and experiences are much richer than that. With schizophrenia and Alzheimer’s disease, there is a fracturing of the thought process. It is constantly disrupted, and despite trying to keep a thought going, one is distracted very easily. Patients with these disorders have trouble sustaining a memory of past decisions to guide later behavior, suggesting a problem with metacognition. -Marc Sommer
Source: University of Pittsburgh
Thinking about others is not child’s play
August 9, 2012
MIT study reveals changes in brain activity as children learn to read other people’s behavior.
When you try to read other people’s thoughts, or guess why they are behaving a certain way, you employ a skill known as theory of mind. This skill, as measured by false-belief tests, takes time to develop: In children, it doesn’t start appearing until the age of 4 or 5.
Several years ago, MIT neuroscientist Rebecca Saxe showed that in adults, theory of mind is seated in a specific brain region known as the right temporo-parietal junction (TPJ). Saxe and colleagues at MIT have now shown how brain activity in the TPJ changes as children learn to reason about others’ thoughts and feelings.
The findings suggest that the right TPJ becomes more specific to theory of mind as children age, taking on adult patterns of activity over time. The researchers also showed that the more selectively the right TPJ is activated when children listen to stories about other people’s thoughts, the better those children perform in tasks that require theory of mind.
The paper, published in the July 31 online edition of the journal Child Development, lays the groundwork for exploring theory-of-mind impairments in autistic children, says Hyowon Gweon, a graduate student in Saxe’s lab and lead author of the paper.
“Given that we know this is what typically developing kids show, the next question to ask is how it compares to autistic children who exhibit marked impairments in their ability to think about other people’s minds,” Gweon says. “Do they show differences from typically developing kids in their neural activity?”
Saxe, an associate professor of brain and cognitive sciences and associate member of MIT’s McGovern Institute for Brain Research, is senior author of the Child Development paper. Other authors are Marina Bedny, a postdoc in Saxe’s lab, and David Dodell-Feder, a graduate student at Harvard University.
Scientists find the stem cells that drive our creativity
A newly-discovered type of stem cell could be the key to higher thinking in humans, research suggests. Scientists have identified a family of stem cells that may give birth to neurons responsible for abstract thought and creativity. The cells were found in embryonic mice, where they formed the upper layers of the brain’s cerebral cortex.
In humans, the same brain region allows abstract thinking, planning for the future and solving problems. Previously it was thought that all cortical neurons - upper and lower layers - arose from the same stem cells, called radial glial cells (RGCs). The new research shows that the upper layer neurons develop from a distinct population of diverse stem cells.
Dr Santos Franco, a member of the US team from the Scripps Research Institute in La Jolla, California, said:
Advanced functions like consciousness, thought and creativity require quite a lot of different neuronal cell types and a central question has been how all this diversity is produced in the cortex. Our study shows this diversity already exists in the progenitor cells.
In mammals, the cerebral cortex is built in onion-like layers of varying thickness. The thinner inside layers host neurons that connect to the brain stem and spinal cord to regulate essential functions such as breathing and movement. The larger upper layers, close to the brain’s outer surface, contain neurons that integrate information from the senses and connect across the two halves of the brain.
Higher thinking functions are seated in the upper layers, which in evolutionary terms are the “newest” parts of the brain. The new research is reported today in the journal Science. Growing the stem cells in the laboratory could pave the way to better treatments for brain disorders such as schizophrenia and autism.