Sensory Neurons Identified as Critical to Sense of Touch

While studying the sense of touch, scientists at Duke Medicine have pinpointed specific neurons that appear to regulate perception. The sensory neurons are characterized by thin spikes, and based on their volume, these protrusions determine the cells’ sensitivity to force.

The findings in fruit fly larvae, which appear in online Oct. 25, 2012, in the journal Current Biology, demonstrate the first known function for the sensory neurons and provide insights that could broaden the understanding of chronic pain syndromes in humans.

"On a molecular level, touch is the most poorly understood of the senses," said W. Daniel Tracey, PhD, associate professor of anesthesiology at Duke University Medical Center and study author. "While there are many types of touch sensor neurons, we still don’t know how these neurons respond to force."

Fruit flies’ eyes shrink a little to see

I spy, with my mechanical eye. It seems a simple mechanical change plays a role in sensory perception in fruit flies, and possibly in many other animals, including humans.

The eyes of the common fruit fly (Drosophila melanogaster) contain clusters of light-sensitive cells organised into rods. When light strikes one of these cells, it triggers a series of chemical reactions. These cause a protein called a transient receptor potential (TRP) ion channel to open. When it’s open, the TRP allows charged particles to flow into the cell, causing the cell to send a signal to the fly’s brain.

TRP channels play a part in sensory perception in many animals, from nematodes to humans. But nobody knew how the chemical signals make the TRP channel open.

Obesity-Related Hormone Discovered in Fruit Flies

Researchers have discovered in fruit flies a key metabolic hormone thought to be the exclusive property of vertebrates. The hormone, leptin, is a nutrient sensor, regulating energy intake and output and ultimately controlling appetite. As such, it is of keen interest to researchers investigating obesity and diabetes on the molecular level. But until now, complex mammals such as mice have been the only models for investigating the mechanisms of this critical hormone. These new findings suggest that fruit flies can provide significant insights into the molecular underpinnings of fat sensing.

“Leptin is very complex,” said Akhila Rajan, first author on the paper and a postdoctoral researcher in the lab of Norbert Perrimon, James Stillman Professor of Developmental Biology at Harvard Medical School. “These types of hormones acquire more and more complex function as they evolve. Here in the fly we’re seeing leptin in its most likely primitive form.”

NYU Biologists Uncover Dynamic Between Biological Clock and Neuronal Activity

Biologists at New York University have uncovered one way that biological clocks control neuronal activity—a discovery that sheds new light on sleep-wake cycles and offers potential new directions for research into therapies to address sleep disorders and jetlag.

“The findings answer a significant question—how biological clocks drive the activity of clock neurons, which, in turn, regulate behavioral rhythms,” explained Justin Blau, an associate professor in NYU’s Department of Biology and the study’s senior author.

Their findings appear in the Journal of Biological Rhythms

Fly neurons could reveal the root of Alzheimer’s disease, says a TAU researcher

Ya’ara Saad, a PhD candidate in the lab of Prof. Amir Ayali at TAU’s Department of Zoology and the Sagol School of Neurosciences. is exploring how neural networks develop one neuron at a time. In the lab, the researchers break the fly’s nervous system down into single cells, separate these cells, then place them at a distance from each other in a Petri dish. After a few days, the neurons begin to grow towards one another and establish connections, and then migrate to form clusters of cells. Finally, they re-organize themselves to form a sophisticated network, says Saad. Because these experiments uniquely allow researchers to concentrate on individual neurons, they can perform specific measurements of proteins, note electrical activity, watch synapses develop, and see how physical changes take shape.

Saad and her fellow researchers are using this technique to observe how neurodegenerative diseases take over the neurons and to potentially test various medicinal interventions. In their experiments, one group of flies is genetically modified so that it expresses a peptide called Amyloid Beta, found in protein-based plaques of human Alzheimer’s disease patients. The results of these studies are then compared to those of a non-modified control group. Both strains of flies are provided by Prof. Daniel Segal of TAU’s Department of Molecular Microbiology and Biotechnology.

Previous studies performed on flies expressing Amyloid Beta showed that they demonstrate Alzheimer’s-like symptoms such as motor problems, impaired learning capabilities, and shorter lifespans. While this peptide has been researched for quite some time, scientists still do not know how it functions. Saad says her work may help unlock the mystery of this function. “Now I can really get into the molecular operation of Amyloid Beta inside the cell. I can watch the dysfunction in the synapses, monitor the proteins involved, and record electrical activity in a much more accessible way,” she says.

The genetic code of the fruit fly Drosophila has been hacked into, allowing it to make proteins with properties that don’t exist in the natural world. The advance could ultimately lead to the creation of new or “improved” life forms in the burgeoning field of synthetic biology.

The four letters of the genetic code, A, C, T and G, are read in triplets, called codons, by the cell’s protein-making machinery. Each codon gives an instruction for the type of amino acid that gets added next in a protein chain, or tells the machinery to stop.

Complex proposition

As a proof of principle, Chin’s team has engineered fruit flies that incorporated three new amino acids into proteins in the cells of their ovaries.

The flies were engineered using bacteria that had been modified to insert the genetic code for the unnatural amino acid into the fly DNA. There was no apparent impact on the flies’ health, and they even produced healthy offspring that also made the new protein chains.

Bulletproof flies

None of the amino acids were particularly remarkable, but the fact that engineering the flies had no obvious impact on their health suggests that many more useful amino acids could be similarly incorporated.

For example, work in bacterial cells has shown that it is possible to incorporate unnatural amino acids that cross-link to each other or turn an enzyme’s activity on or off when a light is shone on them. Doing this in a complex organism like a fly could shed new light on how proteins interact within cells, or how rapidly turning an enzyme on or off affects the cell’s function.

The technique could even be used to create animals with new or improved properties, although that is probably some years off.

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.

Fruit Flies On Methamphetamine Die Largely as a Result of Anorexia

The abuse of methamphetamine can have significant harmful side effects in humans. It burdens the body with toxic metabolic byproducts and weakens the heart, muscles and bones. It alters energy metabolism in the brain and kills brain cells.

Previous studies have shown that the fruit fly Drosophila melanogaster is a good model organism for studying the effects of methamphetamine on the body and brain. Researchers have found that meth exposure has similar toxicological effects in fruit flies and in humans and other mammals.

In the insect brain, dopamine-releasing nerve cells are crucial to the formation of both punished and rewarded memories.

Hiromu Tanimoto and his colleagues at the Max Planck Institute of Neurobiology recently localised and identified the most important types of nerve cells involved in forming positive and negative memories of a fruit fly. All four nerve cell types they discovered use dopamine to communicate with other nerve cells. The dopamine signals released by these cells are received in the mushroom body, a prominent brain structure in insect brains. “It is really surprising that similar dopamine-releasing nerve cells can play such different roles,” says Tanimoto.

Read more: Dopamine – A substance with many messages