Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

One gene provides fruit fly both antenna and color vision

06.04.2006
Brilliant reception

A team of researchers that includes biologists from Washington University in St. Louis has discovered that a gene involved in the development and function of the fruit fly antenna also gives the organism its color vision.


Pretty fly - for a fruit fly. The areas stained blue are regions in the fruit fly where the spineless gene is expressed. WUSTL biologists Ian and Dianne Duncan have spent years making discoveries of how the gene is involved in making the fruit fly antenna. Now they are part of a team that has found that spineless plays a key role in the organism’s color vision.

Claude Desplan, Ph.D., professor of biology at New York University, and his students made the discovery and provided the data. Ian Duncan, Washington University professor of biology, and his wife, research assistant Dianne Duncan, provided the Desplan laboratory fruit fly (Drosophila) clones and mutants and technical assistance that helped locate where the gene, called spineless, is expressed in the retina.

The Duncans have a long history with the spineless gene. Their interest has been in the role spineless plays in directing development of the antenna, Drosophila’s primary olfactory organ. Years ago, they deleted the spineless gene and found that the mutants then produced a leg instead of an antenna.

"Spineless plays a key role in the antenna and maxillary palp, the two major olfactory organs of the fly," said Ian Duncan. "It’s also important in mechanosensory bristles and in the taste receptors of the legs, wings, and mouth parts. There has been a sensory theme to the gene, and now we learn from Claude’s work that it plays a key role in color vision."

In humans the closest known homolog (counterpart) is the arylhydrocarbon (’dioxin’) receptor, a key protein in human health that senses a wide variety of synthetic compounds and then activates expression of detoxification genes. The dioxin receptor is studied closely in cancer biology and toxicology.

Recently, the Duncans had found a relationship between spineless and a gene called homothorax. Desplan’s group had shown that homothorax plays an important role in the Drosophila eye, and after hearing Ian Duncan make a presentation on the homothorax-spineless relationship in the antenna, the Desplan laboratory decided to study spineless in the eye.

The collaborators published their results in the March 9, 2006 issue of Nature.

Random pattern

The Drosophila retina is comprised of clusters of photosensitive cells called ommatidia. Two types of ommatidia are present: one is sensitive to long-wave light and the other to short-wave light. This difference is due to the expression of different light-sensitive pigments (rhodopsins) in the two central photoreceptor cells (R7 and R8) of each ommatidial cluster. Spineless determines the long-wave type by activating expression of rhodopsin-4 in R7 cells. In ommatidia where spineless is not expressed, R7 expresses the short-wave sensitive rhodopsin-3.

"The fascinating thing in this work is that the longer wave length sensitive ommatidia are randomly positioned," said Duncan. "About 70 percent of the ommatidia sense longer wavelength and 30 percent sense short-wave length. It’s been a mystery how you generate a random pattern like that and still have that ratio."

Using the tools that the Duncan laboratory provided, Desplan’s group mapped the regulatory region in the spineless gene that drives the random pattern mechanism.

"Nobody knew what controlled this random pattern," said Dianne Duncan. "Now we know it’s spineless. We’ve known for a while that spineless has several sensory functions and we thought it might be a bit underrated in developmental biology. Now we add color vision to its duties."

Spineless also appears to control communication between the R7 and R8 photoreceptors. "It has been known for some time that the expression of rhodopsin genes in R7 and R8 is coupled with the particular genes expressed in R8 being determined by the adjacent R7 cells," said Ian Duncan.

"An additional important finding in the paper is that spineless controls this signaling between R7 and R8."

Link to human odor perception

The Duncans will continue to look for other genes that spineless controls in making an antenna. They have shown that spineless acts together with two other factors, Homothorax and Distalless, and identified downstream target genes by virtue of their having clustered binding sites for these factors. And they are looking into similarities between spineless and the mammalian dioxin receptor. In a collaboration with a University of Wisconsin researcher, they have put the mammalian dioxin receptor gene into Drosophila, where, surprisingly, it specifies the making of an antenna.

"When you think about it, the antenna is quite special," Dianne Duncan said. "It contains many proteins not expressed anywhere else in the fly. These include many odor receptor proteins that are expressed in subsets of cells within the antenna. Our hope is that by unraveling how development of the Drosophila antenna is controlled, we will gain important insights into how human odor perception works."

Tony Fitzpatrick | EurekAlert!
Further information:
http://www.wustl.edu

More articles from Life Sciences:

nachricht Ambush in a petri dish
24.11.2017 | Friedrich-Schiller-Universität Jena

nachricht Meadows beat out shrubs when it comes to storing carbon
23.11.2017 | Norwegian University of Science and Technology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New proton record: Researchers measure magnetic moment with greatest possible precision

High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons

The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

IceCube experiment finds Earth can block high-energy particles from nuclear reactions

24.11.2017 | Physics and Astronomy

A 'half-hearted' solution to one-sided heart failure

24.11.2017 | Health and Medicine

Heidelberg Researchers Study Unique Underwater Stalactites

24.11.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>