Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Clockwork in the eye of a fly

03.04.2013
The blue-light pigment cryptochrome is important in regulating the circadian clock of many organisms. Scientists have now discovered that in the fruit fly Drosophila it also intervenes in the visual process. The central experiments involved were conducted at the University of Würzburg’s Biocenter.
Timing is everything in the life of all organisms: plants sprout when spring is coming, bees know what flowers are open at what time of year, people tire in the evening and wake up again in the morning, and even single-celled organisms possess a circadian clock. The fruit fly Drosophila melanogaster also has a series of so-called clock genes that dictate its behavior.

With regard to the timing mechanism of the fruit fly, scientists from the universities of Padua, Ferrara, and Würzburg have now discovered a surprising detail: “We have been able to show that the blue-light pigment cryptochrome in the eye of the fly interacts with an important component of the phototransduction cascade, the protein complex InaD,” says Professor Charlotte Förster. The researchers present their work in the current issue of the scientific journal PNAS.

Charlotte Förster has been a professor at the University of Würzburg since September 2009 and chairs its Department of Neurobiology and Genetics. Chronobiology, the temporal order of all living organisms, is this biologist’s specialty. She is also a spokesperson for the Collaborative Research Center “Insect timing: mechanisms, plasticity and interactions”, which began its work at the start of this year. It too addresses the question of how circadian clocks work in the animal kingdom.

Intervention in the visual process

The fact that cryptochrome intervenes in the visual process, is news to the science world. “Until now, cryptochrome was regarded as an important photoreceptor in the circadian clock of the fly,” says Förster. In special nerve cells known as clock neurons, cryptochrome interacts with the clock protein Timeless upon exposure to light and ensures that this protein is degraded. It was not previously known that cryptochrome had any effect on the visual process and therefore on the membranes of photoreceptor cells.

These molecular processes were uncovered by scientists from Italy involved in the publication. Charlotte Förster’s team was responsible for the corresponding behavioral experiments that made it possible to prove on a living object that cryptochrome does indeed influence the visual process.

The experiments

“The light sensitivity of the eyes is modulated in all animals by the circadian clock,” explains Charlotte Förster. Eyes are generally more sensitive at night than during the day. In flies, the easiest way to test light sensitivity is with behavioral experiments. For this purpose, the scientists measured the tendency of the insects to approach a light source or to follow a stripe pattern rotating around them. “Both responses are stronger at night, when the photoreceptor cells of the eye are more sensitive, than during the day,” says the biologist. In fact, Förster’s colleague, Matthias Schlichting, revealed in his experiments that flies lacking the gene for cryptochrome do not exhibit this rhythm. Their response permanently remains at the minimum level that is measurable during daytime.

Measurement on the retina

Since these measurable behavioral responses are “at the end of the whole visual process”, so to speak, and can be altered by numerous external and internal influences, the scientists also measured the light sensitivity of the eye using direct means. This was the responsibility of Rudi Grebler, another member of Förster’s department. Grebler measured, among other things, the response of the cells in the retina of flies when presented with a flash of light. This revealed that in this case, too, the light sensitivity of the eye of flies lacking the gene for cryptochrome was altered in the same way as in the behavioral experiments: there was no circadian modulation, and the photoreceptor cells of the eye no longer demonstrated maximal sensitivity.

The scientists therefore drew the following conclusion: “Cryptochrome seems to be an important mediator between the circadian clock and the light sensitivity of the eye. This appears to happen through interaction
with the protein InaD.”

“Fly cryptochrome and the visual system”. Gabriella Mazzotta, Alessandro Rossi, Emanuela Leonardi, Moyra Mason, Cristiano Bertolucci, Laura Caccin, Barbara Spolaore, Alberto J. M. Martin, Matthias Schlichting, Rudi Grebler, Charlotte Helfrich-Förster, Stefano Mammi, Rodolfo Costa and Silvio C. E. Tosatto. PNAS Online Early Edition, March 25, 2013. www.pnas.org/cgi/doi/10.1073/pnas.1212317110

Contact
Prof. Dr. Charlotte Förster, +49 (0)931 31-88823, charlotte.foerster@biozentrum.uni-wuerzburg.de

Gunnar Bartsch | idw
Further information:
http://www.uni-wuerzburg.de

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Supersensitive through quantum entanglement

28.06.2017 | Physics and Astronomy

X-ray photoelectron spectroscopy under real ambient pressure conditions

28.06.2017 | Physics and Astronomy

Mice provide insight into genetics of autism spectrum disorders

28.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>