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- 검색키워드
- 저자 : Montell, Craig (검색결과 9 건)
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<i>Drosophila</i> TRPA1 Functions in Temperature Control of Circadian Rhythm in Pacemaker Neurons
Lee, Youngseok,Montell, Craig Society for Neuroscience 2013 The Journal of neuroscience Vol.33 No.16
<P>Most animals from flies to humans count on circadian clocks to synchronize their physiology and behaviors. Daily light cycles are well known environmental cues for setting circadian rhythms. Warmer and cooler temperatures that mimic day and night are also effective in entraining circadian activity in most animals. Even vertebrate organisms can be induced to show circadian responses through exposure to temperature cycles. In poikilothermic animals such as <I>Drosophila</I>, temperature differences of only 2–3°C are sufficient to synchronize locomotor rhythms. However, the molecular sensors that participate in temperature regulation of circadian activity in fruit flies or other animals are enigmatic. It is also unclear whether such detectors are limited to the periphery or may be in the central brain. Here, we showed that <I>Drosophila</I> TRPA1 (transient receptor potential cation channel A1) was necessary for normal activity patterns during temperature cycles. The <I>trpA1</I> gene was expressed in a subset of pacemaker neurons in the central brain. In response to temperature entrainment, loss of <I>trpA1</I> impaired activity, and altered expression of the circadian clock protein period (Per) in a subset of pacemaker neurons. These findings underscore a role for a thermoTRP in temperature regulation that extends beyond avoidance of noxious or suboptimal temperatures.</P>
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Multiple gustatory receptors required for the caffeine response in Drosophila.
Lee, Youngseok,Moon, Seok Jun,Montell, Craig National Academy of Sciences 2009 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.106 No.11
<P>The ability of insects to detect and avoid ingesting naturally occurring repellents and insecticides is essential for their survival. Nevertheless, the gustatory receptors enabling them to sense toxic botanical compounds are largely unknown. The only insect gustatory receptor shown to be required for avoiding noxious compounds is the Drosophila caffeine receptor, Gr66a. However, this receptor is not sufficient for the caffeine response, suggesting that Gr66a may be a subunit of a larger receptor. Here, we report that mutations in the gene encoding the gustatory receptor, Gr93a, result in a phenotype identical to that caused by mutations in Gr66a. This includes an inability to avoid caffeine or the related methylxanthine present in tea, theophylline. Caffeine-induced action potentials were also eliminated in Gr93a-mutant animals, while the flies displayed normal responses to other aversive compounds or to sugars. The Gr93a protein was coexpressed with Gr66a in avoidance-gustatory receptor neurons (GRNs), and functioned in the same GRNs as Gr66a. However, misexpression of both receptors in GRNs that normally do not express either Gr93a or Gr66a does not confer caffeine sensitivity to these GRNs. Because Gr93a- and Gr66a-mutant animals exhibit the identical phenotypes and function in the same cells, we propose that they may be caffeine coreceptors. In contrast to mammalian and Drosophila olfactory receptors and mammalian taste receptors, which are monomeric or dimeric receptors, we propose that Drosophila taste receptors that function in avoidance of bitter compounds are more complex and require additional subunits that remain to be identified.</P>
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Moon, Seok Jun,Lee, Youngseok,Jiao, Yuchen,Montell, Craig Elsevier 2009 Current biology Vol.19 No.19
<P><B>Summary</B></P><P>Contact chemosensation is required for several behaviors that promote insect survival. These include evasive behaviors such as suppression of feeding on repellent compounds, known as antifeedants, and inhibition of male-to-male courtship. However, the gustatory receptors (GRs) required for responding to nonvolatile avoidance chemicals are largely unknown. Exceptions include <I>Drosophila</I> GR66a and GR93a, which are required to prevent ingestion of caffeine <ce:cross-refs refid='bib1 bib2'>[1, 2]</ce:cross-refs>, and GR32a, which is necessary for inhibiting male-to-male courtship <ce:cross-ref refid='bib3'>[3]</ce:cross-ref>. However, GR32a is dispensable for normal taste. Thus, distinct GRs may function in sensing avoidance pheromones and antifeedants. Here, we describe the requirements for GR33a, which is expressed widely in gustatory receptor neurons (GRNs) that respond to aversive chemicals. <I>Gr33a</I> mutant flies were impaired in avoiding all nonvolatile repellents tested, ranging from quinine to denatonium, lobeline, and caffeine. <I>Gr33a</I> mutant males also displayed increased male-to-male courtship, implying that it functioned in the detection of a repulsive male pheromone. In contrast to the broadly required olfactory receptor (OR) OR83b, which is essential for trafficking other ORs <ce:cross-ref refid='bib4'>[4]</ce:cross-ref>, GR66a and GR93a are localized normally in <I>Gr33a</I> mutant GRNs. Thus, rather than regulating GR trafficking, GR33a may be a coreceptor required for sensing all nonvolatile repulsive chemicals, including tastants and pheromones.</P>
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A Drosophila Gustatory Receptor Required for Strychnine Sensation
Lee, Youngseok,Moon, Seok Jun,Wang, Yijin,Montell, Craig Oxford University Press 2015 Chemical senses Vol.40 No.7
<P>Strychnine is a potent, naturally occurring neurotoxin that effectively protects plants from animal pests by deterring feeding behavior. In insects, such as the fruit fly, <I>Drosophila melanogaster</I>, bitter-tasting aversive compounds are detected primarily through a family of gustatory receptors (GRs), which are expressed in gustatory receptor neurons. We previously described multiple GRs that eliminate the behavioral avoidance to all bitter compounds tested, with the exception of strychnine. Here, we report the identity of a strychnine receptor, referred to as GR47a. We generated a mutation in <I>Gr47a</I> and found that it eliminated strychnine repulsion and strychnine-induced action potentials. GR47a was narrowly tuned, as the responses to other avoidance compounds were unaffected in the mutant animals. This analysis supports an emerging model that Drosophila GRs fall broadly into two specificity classes—one class is comprised of core receptors that are broadly required, whereas the other class, which includes GR47a, consists of narrowly tuned receptors that define chemical specificity.</P>
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An Odorant-Binding Protein Required for Suppression of Sweet Taste by Bitter Chemicals
Jeong, Y.,Shim, J.,Oh, S.,Yoon, H.,Kim, C.,Moon, S.,Montell, C. Cell Press 2013 Neuron Vol.79 No.4
Animals often must decide whether or not to consume a diet that contains competing attractive and aversive compounds. Here, using the fruit fly, Drosophila melanogaster, we describe a mechanism that influences this decision. Addition of bitter compounds to sucrose suppressed feeding behavior, and this inhibition depended on an odorant-binding protein (OBP) termed OBP49a. In wild-type flies, bitter compounds suppressed sucrose-induced action potentials, and the inhibition was impaired in Obp49a mutants. However, loss of OBP49a did not affect action potentials in sugar- or bitter-activated gustatory receptor neurons (GRNs) when the GRNs were presented with just one type of tastant. OBP49a was expressed in accessory cells and acted non-cell-autonomously to attenuate nerve firings in sugar-activated GRNs when bitter compounds were combined with sucrose. These findings demonstrate an unexpected role for an OBP in taste and identify a molecular player involved in the integration of opposing attractive and aversive gustatory inputs.
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Calcium Taste Avoidance in <i>Drosophila</i>
Lee, Youngseok,Poudel, Seeta,Kim, Yunjung,Thakur, Dhananjay,Montell, Craig Cell Press 2018 Neuron Vol.97 No.1
<P><B>Summary</B></P> <P>Many animals, ranging from vinegar flies to humans, discriminate a wide range of tastants, including sugars, bitter compounds, NaCl, and sour. However, the taste of Ca<SUP>2+</SUP> is poorly understood, and it is unclear whether animals such as <I>Drosophila melanogaster</I> are endowed with this sense. Here, we examined Ca<SUP>2+</SUP> taste in <I>Drosophila</I> and showed that high levels of Ca<SUP>2+</SUP> are aversive. The repulsion was mediated by two mechanisms—activation of a specific class of gustatory receptor neurons (GRNs), which suppresses feeding and inhibition of sugar-activated GRNs, which normally stimulates feeding. The distaste for Ca<SUP>2+</SUP>, and Ca<SUP>2+</SUP>-activated action potentials required several members of the variant ionotropic receptor (IR) family (IR25a, IR62a, and IR76b). Consistent with the Ca<SUP>2+</SUP> rejection, we found that high concentrations of Ca<SUP>2+</SUP> decreased survival. We conclude that gustatory detection of Ca<SUP>2+</SUP> represents an additional sense of taste in <I>Drosophila</I> and is required for avoiding toxic levels of this mineral.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Vinegar flies taste Ca<SUP>2+</SUP> and reject foods that contain high levels </LI> <LI> Ca<SUP>2+</SUP> suppresses feeding through opposing effects on two classes of taste neurons </LI> <LI> Members of the ionotropic receptor (IR) family are required for sensing Ca<SUP>2+</SUP> in food </LI> <LI> Flies taste and avoid foods with high levels of Ca<SUP>2+</SUP> to avoid Ca<SUP>2+</SUP> toxicity </LI> </UL> </P>
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Y. Ladner,D. Liu,J. Montels,J. Morel,C. Perrin 한국바이오칩학회 2022 BioChip Journal Vol.16 No.3
The present work is a proof-of-concept study that nanodroplet microfluidics technology is a tool for the quality control of monoclonal antibodies (mAb). The aqueous nanodroplets mixing on-demand inside the microfluidic channel permits to perform enzymatic reactions in an automated and controlled manner. First of all, nanodroplets generation and mixing were optimized regarding the choice of organic solvent and pressures applied on inlet ports. This optimization phase permits to perfectly control the amount of each reactant mixed in each nanodroplet. Then, in-line degradation of fluorescein isocyanate (FITC) in presence of the Horseradish peroxidase (HRP) enzyme was realized in a microchannel to show the ability of nanodroplet microfluidics technology to generate biochemical reactions. Enzymatic reactions involving trypsin and a monoclonal antibody (trastuzumab) (bottom-up approach) were also realized at a different enzyme to substrate (E/S) ratio by controlling the nanodroplets volume mixed inside microchannels. The determination of the amount of HRP grafted on the active binding sites of mAb surfaces (labeled molecule used in analytical biochemistry assay) was also realized. Successful and repeatable reactions were obtained demonstrating the power of the proposed methodology.
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