 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
| . |  |
. |
How Monarch Butterflies Are Wired For Navigation
In their extraordinary annual migration from North America to Mexico, monarch butterflies are known to use the angle of polarized sunlight as a celestial guide to help them keep to a straight and true path southward. But details of their navigational machinery have remained a mystery. Now, researchers, led by Steven Reppert of University of Massachusetts Medical School, Ivo Sauman of the Czech Academy of Sciences and Adriana Briscoe of the University of California at Irvine, have explored the infinitesimal butterfly brain to uncover new insights into that machinery. Their findings show that the same ultraviolet light that has become an anathema to cancer-wary humans is critical for butterfly navigation. Also, the researchers were surprised to discover a key wiring connection between the light-detecting navigation sensors in the butterfly's eye and the creature's circadian clock - a critical link if the butterflies are to compensate for the time of day in using their "sun compass." The researchers' techniques include molecular analysis of butterfly brain proteins, as well as flight tests in which the scientists manipulated the light reaching their insect subjects and measured the navigational response. In their studies, the researchers discovered that ultraviolet photoreceptors dominated in the region of the butterfly visual system known to specialize in polarized light detection. To confirm that the butterflies, indeed, required ultraviolet polarized light to navigate, the researchers tested the insects in a "flight simulator," in which they could control the light polarization and thus influence the butterflies' direction of flight. The researchers found that when they placed a UV-interference filter over the polarized light source, the butterflies lost their orientation response. The researchers also pinpointed the location of the circadian clock in the butterfly brain. Such circadian clocks govern the approximately 24 hour activity and metabolic cycles of animals from the simplest insects to humans. Reppert and his colleagues found that key genes responsible for the clock's molecular "ticks" were expressed in a brain region called the dorsolateral protocerebrum. Using tracer molecules, they were surprised to discover tiny neural fibers containing a key clock protein that connected with the polarization photoreceptors in the butterfly eye. "This pathway has not been described in any other insect, and it may be a hallmark feature of butterflies that use a time-compensated sun compass," wrote the researchers. They also speculated that another such clock-related pathway of fibers they detected between two regions of the butterfly brain may play a role in regulating the insects' hormonal system, to induce the longevity that enables the butterfly to extend its survival in its overwintering grounds in Mexico. The researchers include Ivo Sauman of the Czech Academy of Sciences; Adriana D. Briscoe of the University of California, Irvine; Haisun Zhu, Dingding Shi, Quan Yuan, Amy Casselman, and Steven M. Reppert of the University of Massachusetts Medical School; Oren Froy of the University of Massachusetts Medical School (Current Address: The Hebrew University of Jerusalem); and Julia Stalleicken of the University of California, Irvine (Current address: University of Oldenburg). This work was supported in part by grants from the NIH, GAAVCR, NSF and German Academy Exchange Service Grant, as well as the Volkswagenstiftung. Related Links Czech Academy of Sciences University of California at Irvine University of Massachusetts Medical School TerraDaily Search TerraDaily Subscribe To TerraDaily Express 
In Search Hints Of Habitability On Mars
Moffett Field CA (SPX) May 05, 2005There are a number of exoplanets which have been detected around other stars, and they are all giant planets like Jupiter. The question is, "Are there any habitable worlds similar to ours?" To answer this, it's crucial to see if there are other habitable planets in our solar system. And so we look at Mars.
|
|
| |||||||||
| The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service. |
