Navigation Links
How Fruitflies Know It's Time for Lunch

To control what you eat and when, your nervous system must coordinate a laundry list of signals: internal signals contain information about energy level, food preferences, and metabolic need, while external signals relay information about the quality of available food, determined by its smell and taste.

Scientists studying the fruitfly Drosophila have traced the path of olfactory signals beginning with chemical receptors in the mouth, which set off neurons that signal the antennal lobe of the central nervous system. From here, the electrical stimulation zooms toward the so-called mushroom body, a mushroom-shaped cluster of neurons involved in olfactory processing. Less is known about the gustatory signals, which begin both in the mouth and in the pharynx and aim toward the subesophageal ganglion region of the fly's brain. How olfactory and gustatory signals influence feeding patterns remains murky.

In a new study, Michael Pankratz and Christoph Melcher used genetic analysis to gain insight into the adult and larval neural networks that use taste information to regulate eating. Specifically, they found that several types of neurons responsible for coordinating taste signals express the gene hugin (hug), a gene linked to abnormal eating activity and expressed in only the subesophageal ganglion. By altering hug expression, the researchers uncovered the gene's behavioral influence: hug-expressing neurons influence a fly's decision to sample new food sources. The researchers also proposed that hug proteins play a role in hormone-triggered growth, an important consequence of adequate feeding.

To begin their investigation, Melcher and Pankratz analyzed the DNA from flies with abnormal eating behavior. One group of these flies shared a mutant klumpfuss (klu) gene, normally responsible for encoding a protein transcription factor. Because neural transcription factors control production levels of other neural proteins, the researchers used DNA microarray s to compare gene expression in normal flies to that in klu mutants. Any klu-controlled genes expressed at different levels in klu mutants might contain clues about the neural circuitry modulating feeding behavior.

Using microarrays, Melcher and Pankratz discovered that mutant fly larvae overexpress the hug gene, which is known to encode at least two neural proteins related to growth signaling. The researchers then investigated which signals influence hug expression by exposing larvae to either high or low food levels. Because both starved and sugar-fed flies express little hug, the researchers inferred that hug levels do not solely signal internal energy requirements but respond to internal and external signals carrying information about the quality of food. The researchers also noted that the finicky pumpless (ppl) mutants, which have a feeding defect similar to klu, overexpress hug.

Behavioral studies confirmed that too much hug reduces food intake and leads to stunted growth, while too little stimulates eating. Melcher and Pankratz selected a group of flies and blocked the synapses of their hug neurons to inhibit the neurons' activity. In contrast to control flies, which start feeding on a novel food source only after an evaluation phase (they wait a while before initiating feeding), the experimental flies started eating new food right away. These hug neurons may help flies decide whether or not to eat a new food source.

Larvae express hug in only about 20 neurons, all located in the subesophageal ganglion. The axons of some of these hug neurons extend into the ring gland, a crucial metabolism and growth organ in flies. Other axons contact the protocerebrum, a structure close to brain centers for learning and remembering odors. A third set of these axons extend to throat muscles—which is surprising because most subesophageal ganglion neurons have no connection to motor function. All together, these few hug neurons can signal structures co ntrolling growth, feeding, and learning and memory.

Besides linking hug neurons to brain centers that regulate taste-related feeding behavior, the study also raises questions about how the nervous system prioritizes internal and external signals. How hungry must flies be to overcome taste aversion? How do the competing neural networks of taste and hunger signals decide whether the fly will eat? Future studies pairing behavioral and genetic analysis may begin to reveal answers to these open questions.


'"/>

Source:PLoS Biology


Related biology news :

1. Quantum Dots Research Leads to New Knowledge about Protein Binding in Plants
2. Plants, animals share molecular growth mechanisms
3. Plants respond similarly to signals from friends, enemies
4. Affymetrix Unveils Plans to Double Plant and Animal Genome Microarray Offering
5. Plant hemoglobins: Oxygen handlers critical for nitrogen fixation
6. Plants defy Mendels inheritance laws, may prompt textbook changes
7. Whats really making you sick? Plant pathologists offer the science behind Sick Building Syndrome
8. Plant Sacrifices Cells to Fight Invaders
9. Breakthrough System for Understanding Ocean Plant Life Announced
10. Plant pathologists evaluate eco-friendly alternatives to methyl bromide
11. Study: Plants use dual defense system to fight pathogens
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:11/21/2016)... Lithuania , Nov. 21, 2016   ... and object recognition technologies, today announced that the ... smart cards was submitted for the NIST ... successfully passed all the mandatory steps of the ... evaluation is a continuing test of fingerprint templates ...
(Date:11/15/2016)... Md. , Nov. 15, 2016  Synthetic ... company developing therapeutics focused on the gut microbiome, ... offering of 25,000,000 shares of its common stock ... common stock at a price to the public ... proceeds to Synthetic Biologics from the offering, excluding ...
(Date:6/22/2016)... , June 22, 2016  The American College of ... Trade Show Executive Magazine as one of the fastest-growing ... May 25-27 at the Bellagio in Las Vegas ... the highest percentage of growth in each of the following ... exhibiting companies and number of attendees. The 2015 ACMG Annual ...
Breaking Biology News(10 mins):
(Date:12/7/2016)... (PRWEB) , ... December 07, ... ... is opening applications to an early access program for SmartBiome -- a ... deep-sequencing with the simultaneous specific enrichment and detection of hundreds of different ...
(Date:12/6/2016)... The American Botanical Council (ABC) recognizes ... ( Arnica montana ) through ABC,s Adopt-an-Herb program. ... database, a comprehensive, interactive online tool that ... data on the uses and health effects of ... a wellness company with healing arts centers, skin ...
(Date:12/6/2016)... PA (PRWEB) , ... December ... ... part of the Almac Group, the world’s largest privately-held contract pharmaceutical development ... with inVentiv Health, a leading biopharma outsourcing company combining a leading CRO ...
(Date:12/6/2016)... ... December 06, 2016 , ... Discovering new clues to natural treatments that ... what’s happening in our brains. And searching for keys to our immune systems by ... honored with the 2017 Edith and Peter O’Donnell Awards by The ...
Breaking Biology Technology: