neuromorphogenesis:

Fly Over the ‘Brainbow’

Two neural mapping techniques illuminate the delicate architecture of flies’ brains.

Four years ago, Harvard scientists devised a way to make mouse neurons glow in a breathtaking array of colors, a technique dubbed “Brainbow.” This allowed scientists to trace neurons’ long arms, known as the dendrites and axons, through the brain with incredible ease, revealing a map of neuron connections. 

Using a clever trick of genetic engineering, in which genes for three or more different fluorescent proteins were combined like paints to generate different hues, researchers created a system to make each neuron glow one of 100 different colors. The result was that the dendrites and axons of individual neurons, previously almost impossible to pick apart from their neighbors, could be traced through the mouse brain according to their color. 

Now, fruit fly researchers have a similar bonanza on their hands. Last week, two Brainbow-based methods for making fly neurons glow customized colors—called dBrainbow and Flybow—were published in Nature Methods. This is the first time that scientists have converted the technique to work in fruit flies, and because these organisms have a very sophisticated set of existing genetic tools, researchers can exert even greater control over when and where the fluorescent proteins are expressed. 

Because axons and dendrites are so long and fine, it’s hard to tell which neurons they are from. Researchers have traditionally had to stain just one or two neurons in each sample, painstakingly compiling data from many brains to build a map. In contrast, many neurons are easily discernible in this cross-section of a fly’s brain made using dBrainbow. Using dBrainbow images, Julie H. Simpson and colleagues at the Howard Hughes Medical Institute’s Janelia Farm could tell which motor neurons controlled parts of a fly’s proboscis, which it uses to take in food.

Both techniques have reduced the number of color options from the original brainbow—dBrainbow has six and Flybow, developed by Iris Salecker and colleagues at the National Institute for Medical Research in London, has four. This makes it easier to identify neurons. 

In dBrainbow, the color indicates which neurons arose from the same progenitor cell during development: each progenitor “decides” what color it will be, and all of its daughter cells will share that color, which is handy for studying how connections between different lineages of neurons are formed. In this shot of a fly’s head, different progenitors gave rise to the blue olfactory neurons on the right and the red olfactory neurons on the left.

In contrast, Flybow cells can be made to “decide” their color at any point in development, because the enzymatic process that causes them to change colors is activated by applying heat. The cells are engineered so their default color is green. The longer they are heated, the more cells will switch from green to blue, yellow, or red. Heat applied early in development produces an effect similar to dBrainbow, while heat applied later produces individual cells that each glow their own color. Here, the visual system of an adult fruit fly shows individual neurons in four colors.

Using existing genetic techniques, scientists can restrict the activation of the dBrainbow and Flybow genes to specific subsets of cells, so only the neurons relevant to their research are visible. In this dBrainbow image, a group of about 2,000 highly studied neurons thought to underlie male courtship behavior are colored according to different subpopulations.

In a typical study, the red, yellow, and blue neurons in this image of a developing fly’s nerve cord would never be seen together, but would instead be spread across many samples, like the pieces of a jigsaw puzzle, leaving scientists to imagine what they might look like in the intact fly. 

“It is a real revelation to see them actually next to each other, at the same time,” says Salecker. “To see them as they are, with their neighbors—it makes a huge difference.”

(via psycholar)

ucsdhealthsciences:

Listeria monocytogenes,

Killing cancer with radioactive microbes

The war on cancer is waged on many fronts, with many weapons, from chemotherapy and nanoparticles to monoclonal antibodies and targeted ultrasound.

In a new commentary published this week in PNAS, Aladar A. Szalay, PhD, in the Department of Radiation Oncology at UC San Diego Moores Cancer Center, and colleague Jochen Stritzker discuss a new (sort of) approach: Microorganisms carrying radioactive antibodies that infiltrate and kill cancer tumors and cells.

To be completely accurate, the work, described in the May 6 online issue of PNAS by Wilber Quispe-Tintaya and colleagues at Albert Einstein College of Medicine in New York City, is not entirely new. In 2009, Robert Hoffman, PhD, in the Department of Surgery at UC San Diego School of Medicine and colleagues reported on experiments with engineered salmonella bacteria, showing that it can kill mouse cancer cells, including metastases of pancreatic cancer.

But the latest Einstein College research is encouraging. It uses a different microorganism – an attenuated or weakened version of Listeria monocytogenes, a food-borne pathogen responsible for listeriosis - to which scientists attach radiolabeled antibodies, then inject the combination into mice with cancer. The reported results have been notable.

In mice injected with just the live L. monocytogenes, primary tumors were reduced in size by 20 percent and metastatic burden – the presence of cancer cells in the body – dropped by 40 percent. Mice injected with just the antibodies experienced no therapeutic effect. In combination, however, the bacteria-and-antibodies treatment reduced primary tumor size by 60 percent and detectable metastases by more than 90 percent.

Just as important, the approach showed no harmful side effects on healthy tissues or liver function. Szalay and Stritzker say the results should stimulate further experimentation, perhaps expanding to other bacteria and viruses with a particular preference and ability to infect and replicate in cancer cells, such as Escherichia coli.

neuromorphogenesis:

Age-defying: Master key of lifespan found in brain

The brain’s mechanism for controlling ageing has been discovered – and manipulated to shorten and extend the lives of mice. Drugs to slow ageing could follow

Tick tock, tick tock… A mechanism that controls ageing, counting down to inevitable death, has been identified in the hypothalamus – a part of the brain that controls most of the basic functions of life.

By manipulating this mechanism, researchers have both shortened and lengthened the lifespan of mice. The discovery reveals several new drug targets that, if not quite an elixir of youth, may at least delay the onset of age-related disease.

The hypothalamus is an almond-sized puppetmaster in the brain. “It has a global effect,” says Dongsheng Cai at the Albert Einstein College of Medicine in New York. Sitting on top of the brain stem, it is the interface between the brain and the rest of the body, and is involved in, among other things, controlling our automatic response to the world around us, our hormone levels, sleep-wake cycles, immunity and reproduction.

While investigating ageing processes in the brain, Cai and his colleagues noticed that ageing mice produce increasing levels of nuclear factor kB (NF-kB)   – a protein complex that plays a major role in regulating immune responses. NF-kB is barely active in the hypothalamus of 3 to 4-month-old mice but becomes very active in old mice, aged 22 to 24 months.

To see whether it was possible to affect ageing by manipulating levels of this protein complex, Cai’s team tested three groups of middle-aged mice. One group was given gene therapy that inhibits NF-kB, the second had gene therapy to activate NF-kB, while the third was left to age naturally.

This last group lived, as expected, between 600 and 1000 days. Mice with activated NF-kB all died within 900 days, while the animals with NF-kB inhibition lived for up to 1100 days.

Crucially, the mice that lived the longest not only increased their lifespan but also remained mentally and physically fit for longer. Six months after receiving gene therapy, all the mice were given a series of tests involving cognitive and physical ability.

In all of the tests, the mice that subsequently lived the longest outperformed the controls, while the short-lived mice performed the worst.

Post-mortem examinations of muscle and bone in the longest-living rodents also showed that they had many chemical and physical qualities of younger mice.

Further investigation revealed that NF-kB reduces the level of a chemical produced by the hypothalamus called gonadotropin-releasing hormone (GnRH)  – better known for its involvement in the regulation of puberty and fertility, and the production of eggs and sperm.

To see if they could control lifespan using this hormone, the team gave another group of mice  – 20 to 24 months old  – daily subcutaneous injections of GnRH for five to eight weeks. These mice lived longer too, by a length of time similar to that of mice with inhibited NF-kB.

GnRH injections also resulted in new neurons in the brain. What’s more, when injected directly into the hypothalamus, GnRH influenced other brain regions, reversing widespread age-related decline and further supporting the idea that the hypothalamus could be a master controller for many ageing processes.

GnRH injections even delayed ageing in the mice that had been given gene therapy to activate NF-kB and would otherwise have aged more quickly than usual. None of the mice in the study showed serious side effects.

So could regular doses of GnRH keep death at bay? Cai hopes to find out how different doses affect lifespan, but says the hormone is unlikely to prolong life indefinitely since GnRH is only one of many factors at play. “Ageing is the most complicated biological process,” he says.

“There are dozens of pathways that people will look at thanks to this work,” says Richard Miller at the University of Michigan in Ann Arbor. Miller has previously demonstrated that an immunosuppressant drug called rapamycin can also extend life in mice (see “A guide to defying age”).

Since the hypothalamus  – and GnRH in particular  – regulate several major biological processes, it may be possible to influence ageing through related mechanisms, says Miller. He wants to look at possible dietary interventions, such as the indirect effect that spikes in glucose may have on the hypothalamus.

Stuart Maudsley at the National Institute on Aging in Baltimore, Maryland, agrees that the hypothalamus could be the route in for age-controlling drugs. “The body is all one big juicy system,” he says. The ideal drug would hit that system at its centre. “Activate that keystone and everything falls into place,” he says.

Though this is the first time that an explicit role has been found for GnRH in the ageing process, previous studies in humans have hinted at a link between longevity and fertility – in which the hormone is known to play a significant role.

As GnRH levels drop, so too does egg production and fertility. In a study presented this month at the annual meeting of the Population Association of America in New Orleans, Graziella Caselli at the University of Rome, Italy, and colleagues found that mothers in Sardinia who’d had their last child over the age of 45  – so were still fertile at a late age  – were significantly more likely to reach 100 than those who’d had their last child at a younger age. Since late fertility could be linked to higher levels of GnRH, Cai says those findings are a good match for his own. “There is likely to be some kind of biological correlation between ageing and reproduction,” he says.

“There are maybe 10 steps to controlling ageing,” says Miller. “We’ve taken the first two or three.” The first is simply accepting the idea that ageing can be slowed down, he says. “Many think it can’t. They are wrong.”

Maudsley reckons that we could see drugs that slow ageing in the next 20 years. Initially, though, research is likely to focus on delaying the onset of age-related diseases. “That could solve some real problems,” says Cai.

But since the hypothalamus has an effect on every cell in the body, Maudsley warns that interfering with it could lead to unwanted sequences of events. “You’re playing with fire,” he says.

Journal reference: Nature, 10.1038/nature12143

(via neuroticthought)

neurosciencestuff:

Scientists Work To Unravel Mystery Behind Woman Who Doesn’t Grow

Twenty year old Brooke Greenberg hasn’t grown since age five. For the last 15 years mystified doctors have been unable to explain the cause for Brooke’s disorder that has kept her aging in check. At age twenty, she maintains the physical and mental appearance of a toddler.

Eric Shadt wants to solve this most bizarre of medical mysteries. Director of the Icahn Institute for Genomics and Multiscale Biology at the Mount Sinai Medical Center in New York, Shadt is leading research to uncover the genetic cause for Brooke’s condition.

Because hormones control many of the maturation processes, one of the first things the research team looked at was to see if Brooke’s own hormone levels might be abnormal. In a piece he wrote on Katie Couric’s website on whose show he and the Greenberg family recently appeared, Shadt explained that Brooke “has no apparent abnormalities in her endocrine system, no gross chromosomal abnormalities, or any of the other disruptions known to occur in humans that can cause developmental issues.”

The researchers are now painstakingly analyzing Brooke’s entire genome in search of unique mutations. Needless to say, it is a formidable undertaking. “Cracking the code on Brooke’s condition,” Shadt wrote, “is the proverbial searching for a needle in a haystack, since likely there is one or a small number of letters changed in Brooke’s genome that has caused her condition.”

(via neuroticthought)

writeswrongs:

cavetocanvas:

Gordon Parks, Dr. Kenneth B. Clark conducting the Doll Test, Harlem, New York, 1947

In the “doll test,” psychologists Kenneth and Mamie Clark used four plastic, diaper-clad dolls, identical except for color. They showed the dolls to black children between the ages of three and seven and asked them questions to determine racial perception and preference. Almost all of the children readily identified the race of the dolls. However, when asked which they preferred, the majority selected the white doll and attributed positive characteristics to it. The Clarks also gave the children outline drawings of a boy and girl and asked them to color the figures the same color as themselves. Many of the children with dark complexions colored the figures with a white or yellow crayon. The Clarks concluded that “prejudice, discrimination, and segregation” caused black children to develop a sense of inferiority and self-hatred. This photograph was taken by Gordon Parks for a 1947 issue of Ebony magazine. (via)

You want to know what is exceptionally fucked up?

The same study was replicated in 2008.  Dark-skinned children still by far selected the white doll.  Repeatedly. 

(via we-are-star-stuff)

jtotheizzoe:

Norovirus: The Human Pathogen That Turns Your Digestive System Into A Two-Way Firehose of Infection

Behold the humble norovirus. The humbly evil norovirus, one of the most perfect human pathogens. To be fair, viruses can’t be evil or not evil, they just want to reproduce. And how that happens to make their hosts feel is none of their concern. Noroviruses are masters of replication and infection, and they wreak havoc on the human digestive system in order to to their bidding.

That’s right. You know where this is going. Carl Zimmer reports, disgustingly:

 Noroviruses come roaring out of the infected cells in vast numbers. And then they come roaring out of the body. Within a day of infection, noroviruses have rewired our digestive system so that stuff comes flying out from both ends.

How can a virus with just nine protein-coding genes do so much damage to a creature (us) with 20,000? Over a million people have come down with norovirus vomitorrhea in just the UK this winter. 

These wee beasties replicate in the digestive system, waiting for you to “eject” them out of one end of your body. People who come in contact with the remnants of that “ejection”, even after cleaning, on planes or other crowded places, can be infected at alarming rates. Chances are it’s happened to you at some point in your life and you just called it a “stomach bug”.

Such a simple biological entity, refined by centuries upon centuries of molecular evolution, to exploit the digestive system of one class of mammals, reproducing in the safe warm home of our gut, and getting a free bi-directional rocket ride to their next host. Viruses never cease to amaze. And sometimes disgust.

Check out more on this virus from Carl Zimmer at Phenomena: The Loom.

(via we-are-star-stuff)

obitoftheday:

Obit of the Day (Historical): Sacagawea (1812)

Sacagawea, the famed Shoshone interpreter who joined Meriweather Lewis and William Clark on their exploration of the American Midwest and Pacific Coast, died on this date 200 years ago. (Coincidentally, she passed away on the 9th anniversary of the transfer of Louisiana to the United States.)

The two men, sent by President Thomas Jefferson to lay out a route to the West through the newly acquired Louisiana Purchase, found Sacagawea and her husband, Toussaint Charbonneau, living near what is today Bismarck, South Dakota.

Kidnapped by the Hidatsa tribe from the Shoshones when she was 12, Sacagawea (which translates as “bird woman”) was 16 when she met the explorers and had just given birth to a son, Jean Baptist Charbonneau. The teenager was purchased by Toussaint to be his wife - along with another woman known only as “Otter Girl” - from the Hidatsas when she was just thirteen

Sacagawea, her son, and her husband would remain with Lewis & Clark for the remainder of their journey to the Pacific and back. She is often misidentified as the guide but was, in fact, their expedition’s interpreter. More importantly, her presence with the group showed to other tribes that the explorers were not looking for conflict, since Native Americans in the region would not include women in war parties.

History also owes Sacagawea a debt of gratitude for her quick thinking when she rescued Lewis and Clark’s records and journals after their boat overturned on May 14, 1805. In return, William Clark named the Sacagawea River, in what is now Montana, in her honor.

Following the expedition, William Clark encouraged Sacagawea and Charbonneau to move to St. Louis, Missouri. Clark then convinced the couple to give him custody of Jean Baptiste and enrolled the boy in a local school.

Six years later Sacagawea gave birth to a daughter named Lizette. Not long after this on December 20, 1812 Sacagawea passed away from an unknown illness. She was only 24 years old. Clark would later adopt both of Sacagawea’s children.

The last mention of Sacagawea in any record is from Clark’s journals of 1825-1826 when he listed all the members of the western expedition and wrote, “Se car ja we au- Dead.”

Random note 1: Although most everyone agrees that Sacagawea died in 1812 there were rumors that she actually survived as a Comanche bride in Wyoming and lived until 1884. No evidence was ever discovered to support this story.

Random note 2: Sacagawea was given a river and historical recognition for her work (as well as a gold dollar coin beginning in 2000) but at the time it was her husband who received $500.33 and 320 acres of land for his work.

Random note 3: Her son, Jean Baptiste, would become a minor celebrity as the only child to travel with Lewis & Clark. At one point he was taken to Europe where he associated with royalty, learned four languages, married, and had a child. After his son died young, Jean Baptiste returned to the U.S. where he became a guide, a gold prospector, and a hotel clerk. He died in 1866 at the age of 61 looking for gold in Montana. Lizette died in childhood.

Sources: PBS.org (check out their tumblr here) and Wikipedia

(Image of the 1994 Sacagawea stamp is courtesy of Stamp of Approval, which is a sister site of the the United States Postal Service’s tumblr. There were no images of Sacagawea created of her during her lifetime.)

(via timesforgotten)