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Fruit flies alter their sleep to beat the heat

April 3, 2016 By

Do you have trouble sleeping at night in the summer when it is really hot?

Does a warm sunny day make you want to take a nap?

You are not alone — fruit flies also experience changes in their sleep patterns when ambient temperature is high. In a new paper in Current Biology, research scientist Katherine Parisky and her co-workers from the Griffith lab show that hot temperatures cause animals to sleep more during the day and less at night, and then investigate the mechanisms governing the behavior.

The increase in daytime sleep is caused by a complex interplay between light and the circadian clock. The balance between daytime gains and nighttime losses at high temperatures is also influenced by homeostatic processes that work to keep total daily sleep amounts constant. This study shows how the nervous system deals with changes caused by environmental conditions to maintain normal operations.

Parisky KM, Agosto Rivera JL, Donelson NC, Kotecha S, Griffith LC. Reorganization of Sleep by Temperature in Drosophila Requires Light, the Homeostat, and the Circadian Clock. Curr Biol. 2016.

Filed Under: Biology, Neuroscience Tagged With: , , , , , ,

Sleep and memory are connected by a pair of neurons in Drosophila

January 18, 2015 By

In a recent post on the Fly on the Wall blog, Neuroscience grad student Bethany Christmann talks about recently published research from Leslie Griffith’s lab:

 … [How are sleep and behavior] connected in the brain? Does sleep simply permit memory storage to take place, such that the part of the brain involved in memory just takes advantage of sleep whenever it can? Or are sleep and memory physically connected, and the same mechanism in the brain is involved in both? In a recent study published in eLife, researchers in the Griffith lab may have [uncovered the answer]. They found that a single pair of neurons, known as the DPM neurons, are actively involved in both sleep and memory storage in fruit flies.

Haynes PR, Christmann BL, Griffith LC. A single pair of neurons links sleep to memory consolidation in Drosophila melanogaster. eLife. 2015;4.

Filed Under: Biology, grad students, Neuroscience Tagged With: , , , , , , ,

The “Fly on the Wall” Blog

August 14, 2014 By

fruit_fly_drawingBethany Christmann, a Neuroscience Ph.D. student in Leslie Griffith’s lab at Brandeis University has created a blog titled Fly on the Wall. The blog’s purpose is to introduce fly science to a broader audience of non-fly scientists. Check it out if you want to learn more about fly life, current research and how fruit fly research has already made huge contributions to understanding human biology and will continue to do so in the future.

Learn more about research in the Griffith Lab.

 

Filed Under: Biology, labs Tagged With: , , , , ,

Another way that flies sense temperature

August 31, 2013 By

If you remember your (bio-)physical chemistry, you’ll remember that most proteins are temperature sensitive. But which ones acts as the sensors that drive behavior in higher organisms? The Garrity Lab at Brandeis has been working on thermosensation in Drosophila, and previous work has implicated the channel protein TRPA1 as a key mediator of temperature preference and thermotaxis,  In a new paper in Nature, members of the Garrity lab working in collaboration with the Griffith and Theobald have have identified another protein, GR28B(D), a member of the family of gustatory receptor proteins, as another behaviorally important temperature sensor, involved in rapid avoidance of high temperatures. Authors on the paper include postdocs Lina Ni (lead author) and Peter Bronk, grad students April Lowell (Mol. Cell Biology) and Vincent Panzano (PhD ’13, Neuroscience), undergraduate Juliette Flam ’12, and technician Elaine Chang ’08.

  • Ni L, Bronk P, Chang EC, Lowell AM, Flam JO, Panzano VC, Theobald DL, Griffith LC, Garrity PA. A gustatory receptor paralogue controls rapid warmth avoidance in Drosophila. Nature. 2013.
  • story at BrandeisNOW

 

Filed Under: Biology, grad students, Neuroscience Tagged With: , , , , , , , ,

To Get The Girl, You Have To Listen… No, Smell!

October 3, 2012 By

KC and the Sunshine band were prophetic when they wrote the song Get Down Tonight in ways that they never could have imagined. In the tiny social world of fruit fly courtship, the directive ‘do a little dance, make a little love’ is right on target. And just like in a dance club, what is said and when/how it is said are important to the success of fly hookups.

In ways not that dissimilar to humans, Drosophila melanogaster fruit flies meet at a singles bar commonly known as a fallen piece of overripe fruit. As the prospects congregate, there is a lot of information that is exchanged. Males use their wings to sing at short distances to the ladies milling about, giving persistent shouts of: (1) “Hey!” and (2) “How you doin’?”. When a female slows her pace to one of these calls from the dance floor, the male can then move in and cut out the ‘Hey’ portion of the call, and just use the more intimate “How you doin’?” signal. If she is still receptive, the male will dance a little closer, touching her butt and showing off his best moves until an eventual one-night-stand is awarded for his efforts. This interesting human/fruit fly parallel shows just how universal mating strategies are, even across 500 million years of evolution.

Also in similar fashion, when a miscommunication occurs, males have a much more difficult time obtaining a mate. The recent paper by Trott et al. (PLoS ONE, 2012) shows that the distance and timing of the two signals is critical to male mating success. Female fruit flies give off a chemical signal (like perfume!) to courting males, telling them that they’re interested, and the distance that the female lingers from the male is reinforcement to the male’s advances. Males who are deficient in their ability to smell due to an olfactory mutation also have a difficult time switching to a dominant “How you doin’?” signal. Without a functioning olfactory feedback mechanism, the male is unable to make the proper adjustments to his signal. For the female, it’s kind of like trying to have a one-on-one conversation with a male that is still trying to pick up every other female in the room. Even though the male is handsome/strong/free of parasites, interest from the female quickly wanes when he keeps giving the wrong signal. All the parts of the song are there; he just can’t read the cues.

So next time you’re out busting a move on the dance floor, think of the noble fruit fly passionately conducting it’s own miniature fandango. What is said is just as important as the moves that are made. And being able to read feedback is crucial to success. In a strange homage to Cyrano de Bergerac, it’s the male fruit fly that uses its ‘nose’ to speak sweet nothings that is best able to woo the female.

Trott AR, Donelson NC, Griffith LC, Ejima A (2012) Song Choice Is Modulated by Female Movement in Drosophila Males. PLoS ONE 7(9): e46025. doi:10.1371/journal.pone.0046025

Alexander Trott ’10 and postdocs Nathan Donelson and Aki Ejima worked on Drosophila courtship together with Prof. Leslie Griffith at Brandeis. Aki is now an Assistant Professor at Kyoto University. Alex is currently a graduate student at Harvard Medical School.

Video courtesy of Dr. Aki Ejima

Filed Under: Biology, labs, Neuroscience Tagged With: , , , , , ,

To sleep, perchance to learn?

May 22, 2012 By

Sleep deprivation is ubiquitous in today’s society, and we have all felt the effects of sleep loss on our ability to function optimally, physically and especially mentally. In particular, it has become clear that the brain requires sleep to efficiently establish many forms of long-term memory. However, it is still unknown what sleep deprivation actually does to the brain to impair its function. In a recently published review in the journal Cellular Signalling, authors Christopher G. Vecsey from Brandeis University and Robbert Havekes and Ted Abel from the University of Pennsylvania have tried to capture the current state of our knowledge about the molecular and cellular effects of sleep deprivation that could explain why sleep loss is so detrimental for memory formation. The review focuses primarily on memories for events and places, which are thought to be formed and stored in the area of the brain called the hippocampus.

A key approach to learn about the nitty-gritty effects of sleep deprivation has been research in rodents. Therefore, the authors begin by summarizing how sleep deprivation studies are carried out in rodents, and how sleep deprivation affects memory and several signaling pathways in the brain. Notably, they review the effects of sleep loss on neurotransmitter systems such as acetylcholine, glutamate, and GABA, all of which could potentially modulate learning and memory. The authors also discuss some of the newest and most exciting studies on the topic of sleep loss, including a handful of experiments in which researchers have been able to reverse the effects of sleep deprivation through pharmacological treatments. For example, the authors describe one of their own studies in which sleep deprivation in mice caused memory deficits and reduced signaling through the cAMP pathway, which is known to be crucial for long-term memory. This molecular effect was likely caused by accelerated breakdown of cAMP by phosphodiesterase 4 (PDE4). When mice were treated with a PDE4 inhibitor during the period of sleep deprivation, memory formation remained unaffected. Rescue of memory defects were also obtained in separate studies in which rodents were treated either with nicotine, caffeine, or CPT, an antagonist of the adenosine A1 receptor. Two related studies also found that the effects of sleep deprivation on memory could be ameliorated by prevention of transmitter release from cells in the brain called glia. This was the first indication that brain cells other than neurons are impacted by sleep deprivation and that they contribute to the effects of sleep loss on the ability to remember new information.

As the authors mention, goals for studies in the immediate future will be to identify additional ways that sleep deprivation affects the brain, determine why sleep deprivation targets these molecules, and discover how these targets interact with each other to impair the normal function of the brain. Finally, hopefully our growing knowledge can be used to develop treatments for the cognitive deficits produced by sleep loss in people, especially those who have impaired sleep due to a medical condition, such as insomnia, chronic pain, sleep apnea, or one of the many neurodegenerative or psychiatric disorders associated with disturbed sleep patterns.

Christopher G. Vecsey is a postdoctoral fellow in the Griffith Lab at Brandeis, where he continues to work on interactions between sleep and learning. Chris is supported by a postdoctoral fellowship from the National Institute of Mental Health.

Filed Under: Neuroscience, postdocs Tagged With: , , , , ,

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