(Press-News.org) (Santa Barbara, Calif.) — Next time you see a fruit fly in your kitchen, don't swat it. That fly could have a major impact on our progress in deciphering sensory biology and animal behavior, including someday providing a better understanding of the human brain.
UC Santa Barbara researchers in the Department of Molecular, Cellular, and Developmental Biology (MCDB) and the Neuroscience Research Institute (NRI) have been studying the mechanisms underlying salt taste coding of Drosophila (fruit flies). And they have made some rather remarkable discoveries. Their findings appear today in the journal Science.
The work done by Craig Montell, Duggan Professor of MCDB and Neuroscience, and his team not only explains the fundamental question of how an animal chooses low salt over high salt, but also unravels the mechanism for how gustatory receptor neurons (GRNs) are activated by salt, an essential nutrient for all animals, including humans.
The fact that animals are attracted to low-salt foods and reject food with high salt is well known. However, it remains unclear how low-salt and high-salt taste perceptions are differentially encoded in gustatory receptor cells, and how they induce distinct behavioral responses. The researchers' findings solve this mystery.
Fruit flies use two distinct types of salt GRNs to respond to different concentrations of salt. One type is activated maximally by low salt and induces attractive feeding behavior. The other class, activated primarily by high salt, leads to aversive feeding behavior. Montell and his colleagues found that these two types of neurons compete with each other to regulate the animal's behavioral outputs. The net outcome of the salt behavioral response is determined by the relative strength of salt-attractive GRNs and salt-aversive GRNs. The identification of the mechanism underlying the coding of salt taste in GRNs represents a conceptual breakthrough.
"Ultimately, what we want to understand is behavior, which depends on sensory input and an animal's genetic makeup," said Montell. "Once you have this information and the neuronal wiring, you can predict the behavior of a population of animals.
By focusing on behavior and perception in fruit flies, it may be just a few years before we have a rather impressive understanding about how sensory perceptions translate into behavior. That's why there's so much attention paid to model organisms like flies."
The paper also demonstrates that a member of the newly discovered ionotropic receptor (IR) family, IR76b, is required for low-salt sensation. Moreover, IR76b codes for a previously unrecognized class of GRNs separate from those that respond to sweet or bitter foods. Loss of IR76b selectively impaired the attractive low-salt pathway, causing low salt to become aversive to the mutant animals.
"The demonstration that IR76b is a Na+ leak channel suggests an unusual mechanism for activating a sensory neuron," said Montell. "We describe a mechanism for neuronal depolarization that is mediated by a change in the concentration of an extracellular ion (Na+), rather than activation of a receptor or ion channel by a specific agonist, leading to opening of a channel gate."
These findings provide compelling genetic evidence supporting the concept that the opposing behavioral responses to low and high salt are determined largely by competition between two newly identified types of salt-responsive GRNs.
"Not only does this comment on how salt perception may occur in many animals throughout the animal kingdom," Montell said, "but if we can fully understand how aversive and attractive sensory signals work in fruit flies, there may be future potential for controlling insect pests. Fruit flies provide a model for insects that spread disease, so one day we may be able to use thermosensory and chemosensory receptors to provide new strategies to control such pests."
INFORMATION: END
Scientists at the University of Liverpool have shed new light on how diving mammals, such as the sperm whale, have evolved to survive for long periods underwater without breathing.
The team identified a distinctive molecular signature of the oxygen-binding protein myoglobin in the sperm whale and other diving mammals, which allowed them to trace the evolution of the muscle oxygen stores in more than 100 mammalian species, including their fossil ancestors.
Myoglobin, which gives meat its red colour, is present in high concentrations in elite mammalian divers, so high ...
Staph infections in hospitals are a serious concern, so much so that the term Methicillin-resistant Staphylococcus aureus (MRSA) is as commonly known as MRI. Far less known is that in many of these cases, patients are infecting themselves.
In heart surgeries and knee and joint-replacement procedures, up to 85 percent of staph infections after surgery come from patients' own bacteria, according to a 2002 study in the New England Journal of Medicine.
Despite the threat that staph bacteria pose to patients, there is no uniformly accepted procedure to reduce surgical-site ...
CHICAGO --- In a surprising new finding, a Northwestern Medicine® study has found a common molecular vulnerability in autism and fetal alcohol spectrum disorder. Both disorders have symptoms of social impairment and originate during brain development in utero.
This the first research to explore a common mechanism for these disorders and link their molecular vulnerabilities.
The study found male offspring of rat mothers who were given alcohol during pregnancy have social impairment and altered levels of autism-related genes found in humans. Female offspring were ...
Why was there a sudden drop in the incidence of leprosy at the end of the Middle Ages? To answer this question, biologists and archeologists reconstructed the genomes of medieval strains of the pathogen responsible for the disease, which they exhumed from centuries old human graves. Their results, published in the journal Science, shed light on this obscure historical period and introduce new methods for understanding epidemics.
In Medieval Europe, leprosy was a common disease. The specter of the leper remains firmly entrenched in our collective memory: a person wrapped ...
Frontiers in Microbiology
Insights into fungal communities in composts revealed by 454-pyrosequencing: Implications for human health and safety
Composting is a process for converting waste into materials beneficial for plant growth through the action of microbes, especially of fungi which can break down large molecules. But fungi involved in composting are not always harmless. Vidya De Gannes and colleagues show that composts can contain more fungi that are potentially harmful to humans than was previously realized. Using intensive DNA-sequencing to analyze fungal ...
Irvine, Calif., June 10, 2013 – New satellite imagery reveals that several areas across the United States are all but certain to suffer water-related catastrophes, including extreme flooding, drought and groundwater depletion.
The paper, to be published in Science this Friday, June 14, underscores the urgent need to address these current and rapidly emerging water issues at the national scale.
"We don't recognize the dire water situation that we face here in the United States," said lead author Jay Famiglietti, a professor of Earth System Science at the University of ...
Sponsors and researchers will be given one year to act before independent scientists begin publishing the results themselves using previously confidential trial documents.
The BMJ and PLOS Medicine have already endorsed the proposal and committed to publishing restorative clinical trial submissions - and will discuss it in more detail at a meeting in London on Friday 14 June 2013.
Unpublished and misreported studies make it difficult to determine the true value of a treatment. Around half of all clinical trials for the medicines we use today have never been published ...
However, the authors stress that the overall risk of severe problems is small and the results are significant only for women who have previously given birth – not for first-time mums.
The relative safety of planned home births is a topic of continuous debate, but studies have so far been too small to compare severe maternal complications between planned home and planned hospital birth among low risk women.
Of all Western countries, the Netherlands has the highest percentage of home births, assisted by a primary care midwife.
So a team of Dutch researchers decided ...
Grenoble, 12 June 2013: Swedish, Australian and French researchers present for the first time miraculously preserved musculature of 380 million year old armoured fish discovered in north-west Australia. This research will help scientists to better understand how neck and abdominal muscles evolved during the transition from jawless to jawed vertebrates. The scientific paper describing the discovery is published today in the journal Science.
The team of scientists who studied the fossilised fish was jointly directed by Prof. Kate Trinajstic, Curtin University, Perth, Australia ...
PITTSBURGH, June 13, 2013 – Allowing all employees access to paid sick days would reduce influenza infections in the workplace, according to a first-of-its-kind analysis by University of Pittsburgh Graduate School of Public Health modeling experts.
The researchers simulated an influenza epidemic in Pittsburgh and surrounding Allegheny County and found that universal access to paid sick days would reduce flu cases in the workplace by nearly 6 percent and estimated it to be more effective for small, compared to large, workplaces. The results are reported in the online version ...