Lasers Zap Heads of Flies to Expose Brains
Ticks resemble little bumps on skin, but a closer look reveals the barbed mouthpart (hypostome) that's inserted in human flesh and can't easily slip out. Dania Richter of the Technical University of Braunschweig watched, under very high magnification, ticks using other mouthparts to pierce skin, generating “a toehold,” before a breaststroke-like action pulled in the barbed hypostome. The study is published in the latest Proceedings of the Royal Society B.
S. Turner, UC Riverside
This scanning electron micrograph image of a southern house mosquito (foreground) makes evident the straw-like mouthpart used to suck human -- and other -- blood. The red and black additions highlight smelling activity. It’s believed that a mosquito can smell a person from 100 feet away.
Spiders in the genus Loxosceles, including the brown recluse, are among the few common spiders whose bites can seriously hurt people. Greta Binford, an associate professor of biology at Lewis and Clark College, recently studied the spiders, including the one shown here from South America. The spider bites can cause our skin to die. "Our bodies are basically committing tissue suicide," she explained. "That can be very minor to pretty major, like losing a big chunk of skin. The only treatment in that case is usually to have a skin graft done by a plastic surgeon."
Older workers within a rainforest termite species,
, have built-in “explosive backpacks” that become bigger and more deadly over time. The blue in this image -- showing several workers and a soldier termite -- is actually a sack of toxic blue liquid. Jan Šobotnik at Academy of Sciences of the Czech Republic in Prague found that worker termites could explode this toxin onto enemies during suicide missions that help their colonies.
Entomologist Michael Caterina and his team studied clown beetles, which munch on fly larvae found in decomposing bodies He snapped this shot, which shows one such beetle’s mandibles. It’s apparently a bug-eat-bug world, even in the remains of the deceased.
Slimy slugs are the bane of gardeners, but a recently discovered slug species makes others seem tame. The ‘ghost slug,’ found in Cardiff, Wales, lives on land, is carnivorous and possesses blade-like teeth. It’s out all year round -- not just on Halloween.
Sam Droege, Flickr
This fly was photographed after it became stuck in a glob of hand sanitizer, so it was likely frozen in this image seconds before its demise. The photo reveals the fly’s compound eyes, which have the fastest visual responses in the animal kingdom. The tongue-like proboscis is also sticking out.
Leeches are predominantly bloodsuckers that feed on blood from humans and other animals. When leeches bite into a victim, their saliva prevents blood from clotting, causing victims to bleed from the wound for hours. The good news is that this effect has beneficial microsurgery applications, such as helping doctors reattach tiny veins.
David Hughes, Penn State University
The zombie-ant fungus invades an ant’s brain, causing the insect to march to its death at a mass grave near the ant colony. The fungus winds up the winner, since it then erupts via spores that come out of the ant’s head. A parasitic fungus, however -- the white and yellow material in this image -- can castrate the zombie-ant fungus, allowing the ant to live.
Linda Tanner, Flickr
Photographer Linda Tanner spotted this black widow spider in an old, dark barn, heading for a front porch. Black widows are very common, and are often found in garage door slats, hiding in dark corners, under woodpiles and in other places in and around homes. Usually they mind their own business, focusing on their insect prey, but their venom can cause human victims to experience nausea, muscle aches and paralysis of the diaphragm, which can lead to breathing difficulties.
Using lasers, scientists can now surgically blast holes thinner than a human hair in the heads of live fruit flies, allowing researchers to see how the flies' brains work.
The researchers also successfully tested this technique on worms, ants and mice.
Microscopically peering into living animals can help scientists learn more about key details of these animals' biology. For instance, tiny glass windows surgically implanted into the sides of living mice can help researchers study how cancers develop in real time and evaluate the effectiveness of potential medicines.
Surgically preparing small live animals for such "intravital microscopy" is often time-consuming and requires considerable skill and dexterity. Now, Supriyo Sinha, a systems engineer at Stanford University in California, and his colleagues have developed a way to prepare live animals for such microscopy that is both fast -- taking less than a second -- and largely automated.
To conduct this procedure, scientists first cooled fruit flies to anesthetize them. Then, the researchers carefully picked up the insects with tweezers and glued them to the tops of glass fibers in order to immobilize the flies' bodies and heads. Then, using a high-energy pulsed ultraviolet laser, the researchers blasted holes measuring 12 to 350 microns wide in the flies' heads. (In comparison, the average human hair is about 100 microns wide.) They then applied a saline solution to exposed tissue to help keep the fly brains healthy. (See Experiment Video).
The scientists then microscopically analyzed brain activity in the fruit flies. The insects in the experiment were genetically modified to generate a protein that emits a green glow in the presence of calcium ions, the flow of which is key to neural activity. By looking through these "windows" into the fruit flies' heads, the researchers successfully monitored calcium-ion-based activity in neurons in response to different smells.
Using lasers enabled the researchers to create these "windows" up to 100 times faster than they could be created manually. Moreover, these laser-cut windows were apparently substantially gentler on fly health than ones created by conventional surgery -- the researchers could image brain activity for longer than they could using the conventional method, up to 18 hours, about five to 20 times longer than prior microscopy studies of living, hand-dissected flies.
"The induced trauma to the fly is minimized, and the fly can remain alive longer," Sinha told LiveScience. "Learning and memory experiments in which the brain is imaged before and after training is possible."
Prior research had tried using laser surgery to open holes in animals for intravital microscopy before. Compared to past work that used infrared, visible or larger-wavelength ultraviolet lasers, this new technique can remove tissue more quickly or cause less collateral damage in the brain.
Sinha and his colleagues also successfully tested their technique on anesthetized and immobilized ants, nematode worms and mice. "Our main motivation is to better understand neural circuits, and faster screening and imaging could better help us reverse-engineer these circuits," Sinha said.
From one to 100
The scientists are also developing a way to automatically capture, mount and align the insects for laser surgery. Their short-term goal is to build a system that can hold a dozen flies.
"We are trying to streamline the procedure such that the experimentalist only has to press one button to have the system pick and mount and align 12 flies; a second button that would surgically remove the cuticle and apply saline to the 12 flies; and a third button to start imaging the 12 flies under predetermined stimulation," Sinha said.
Ultimately the researchers would like to simultaneously image the brains of about 100 awake fruit flies with a push of a few buttons, Sinha added.
"Our goal is to have this arrayed imaging technology adopted by a few other labs in the world," Sinha said. "These imaging centers could be used by fly biologists all over the world to conduct new classes of experiments that would not be possible or would be too impractical using traditional techniques."
The scientists detailed their findings online Oct. 28 in the journal Proceedings of the National Academy of Sciences.
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