scholarly journals The ion channel ppk301 controls freshwater egg-laying in the mosquito Aedes aegypti

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Benjamin J Matthews ◽  
Meg A Younger ◽  
Leslie B Vosshall
Keyword(s):  
Aedes Aegypti ◽  
Ion Channel ◽  
Sensory Neurons ◽  
Calcium Imaging ◽  
High Salinity ◽  
Egg Laying ◽  
Low Salt ◽  
Human Habitation ◽  
Chemosensory Systems ◽  
Water Purity

Female Aedes aegypti mosquitoes are deadly vectors of arboviral pathogens and breed in containers of freshwater associated with human habitation. Because high salinity is lethal to offspring, correctly evaluating water purity is a crucial parenting decision. We found that the DEG/ENaC channel ppk301 and sensory neurons expressing ppk301 control egg-laying initiation and choice in Ae. aegypti. Using calcium imaging, we found that ppk301-expressing cells show ppk301-dependent responses to water but, unexpectedly, also respond to salt in a ppk301-independent fashion. This suggests that ppk301 is instructive for egg-laying at low-salt concentrations, but that a ppk301-independent pathway is responsible for inhibiting egg-laying at high-salt concentrations. Water is a key resource for insect survival and understanding how mosquitoes interact with water to control different behaviors is an opportunity to study the evolution of chemosensory systems.

scholarly journals The ion channel ppk301 controls freshwater egg-laying in the mosquito Aedes aegypti

2018 ◽  
Author(s):  
Benjamin J. Matthews ◽  
Meg A. Younger ◽  
Leslie B. Vosshall
Keyword(s):  
Aedes Aegypti ◽  
Disease Transmission ◽  
Egg Laying ◽  
Genetic Tools ◽  
Low Salt ◽  
Close Range ◽  
Human Habitation ◽  
In Vivo Calcium Imaging ◽  
Chemosensory Systems

Aedes aegypti mosquitoes are deadly vectors of arboviral pathogens including Zika, dengue, and yellow fever, and breed in containers of freshwater associated with human habitation1,2. Female Ae. aegypti lay eggs near freshwater because larval and pupal stages are aquatic3. They use volatile cues to locate water at a distance4, while at close-range they contact water to evaluate its suitability for egg-laying4–7. High salinity is lethal to mosquito offspring and therefore correctly laying eggs in freshwater is a crucial parenting decision made by female mosquitoes. Here we show that the DEG/ENaC channel8–10ppk301 is required for mosquitoes to exploit freshwater egg-laying substrates. When ppk301 mutant females contact water, they do not lay eggs as readily as wild-type animals and are more likely to make aberrant decisions between freshwater and saltwater at concentrations that impair offspring survival. We used a CRISPR-Cas9-based genetic knock-in strategy combined with the Q-binary transactivator system11 to build genetic tools for labelling and imaging neurons in the mosquito. We found that ppk301 is expressed in sensory neurons in legs and proboscis, appendages that directly contact water, and that ppk301-expressing neurons project to central taste centres. Using in vivo calcium imaging with the genetically-encoded calcium sensor GCaMP6s12, we found that ppk301-expressing cells respond to water but, unexpectedly, also to salt. This suggests that ppk301 is instructive for egg-laying at low salt concentrations but that a ppk301-independent pathway is responsible for inhibiting egg-laying at high salt concentrations. Water is a key resource for insect survival and understanding how mosquitoes interact with water to control different behaviours is an opportunity to study the evolution of chemosensory systems. The new genetic tools described here will enable direct study of not only egg-laying, but also other behaviours in mosquitoes that influence disease transmission and enable comparative studies of insect biology more broadly.

Human inducible pluripotent stem cell-derived sensory neurons express multiple functional ion channels and GPCRs

2013 ◽  
Vol 4 (4) ◽  
pp. 260
Author(s):  
M. Saarnilehto ◽  
M. Pekkanen-Mattila ◽  
K. Aalto-Setälä ◽  
O. Silvennoinen ◽  
A. Koivisto
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Ion Channels ◽  
Ion Channel ◽  
Intracellular Calcium ◽  
Single Cell ◽  
Sensory Neurons ◽  
Pluripotent Stem Cells ◽  
Calcium Imaging ◽  
Pluripotent Stem Cell

AbstractAimsAim of the study was to characterize functional ion channel and GPCR responses by using selective pharmacological tools and intracellular calcium imaging from human inducible pluripotent stem cell-derived sensory neurons.MethodsSensory neurons were generated from human keratinocytes that were reprogrammed to inducible pluripotent stem cells by using standard Yamanaka factors. Inducible pluripotent stem cells were differentiated into sensory neurons by using 2 differentiation protocols (small molecule and PA6 co-culture). Sensory neurons were loaded with intracellular calcium dye Fluo-4. Single-cell calcium imaging was performed with Photometrics Evolve EM-CCD camera at physiological temperature. Cells were perfused with a Ringer solution at 2–3 ml/min into which pharmacological compounds were dissolved. Data was analyzed with Till Photonics Offline Analysis program.ResultsMost of the results were obtained from PA6 differentiated neurons. 50 s application of 50 mM KCl solution was used as diagnostic tool to activate voltage-gated calcium channels and thereby evoke intracellular calcium elevation. Functional ASIC, NMDA, kainate and TRPA1 ion channels were present in a subset of sensory neurons. Majority of sensory neurons showed robust responses to purinergic stimulation with ATP and histaminergic stimulation with histamine, but not to subtype selective histamine H1, H2 or H4 stimulation suggesting the presence of H3 receptor subtype All cells responded strongly to protease-activated receptor stimulation with a low dose of trypsin. Interestingly, at single-cell level notable heterogeneity of ion channel and GPCR responses was observed.ConclusionsOur results suggest that iPS-derived sensory neurons will be valuable in further pharmacological studies as well as sensory neuropathy disease modeling.

scholarly journals Widespread inhibition, antagonism, and synergy in mouse olfactory sensory neurons in vivo

2019 ◽  
Author(s):  
Shigenori Inagaki ◽  
Ryo Iwata ◽  
Masakazu Iwamoto ◽  
Takeshi Imai
Keyword(s):  
Sensory Neurons ◽  
Calcium Imaging ◽  
Odorant Receptor ◽  
Sensory Information ◽  
Olfactory Sensory Neurons ◽  
Axon Terminals ◽  
Two Photon ◽  
Odor Mixtures ◽  
The Brain

SUMMARYSensory information is selectively or non-selectively inhibited and enhanced in the brain, but it remains unclear whether this occurs commonly at the peripheral stage. Here, we performed two-photon calcium imaging of mouse olfactory sensory neurons (OSNs) in vivo and found that odors produce not only excitatory but also inhibitory responses at their axon terminals. The inhibitory responses remained in mutant mice, in which all possible sources of presynaptic lateral inhibition were eliminated. Direct imaging of the olfactory epithelium revealed widespread inhibitory responses at OSN somata. The inhibition was in part due to inverse agonism toward the odorant receptor. We also found that responses to odor mixtures are often suppressed or enhanced in OSNs: Antagonism was dominant at higher odor concentrations, whereas synergy was more prominent at lower odor concentrations. Thus, odor responses are extensively tuned by inhibition, antagonism, and synergy, at the early peripheral stage, contributing to robust odor representations.

The Global Expansion of Dengue: How Aedes aegypti Mosquitoes Enabled the First Pandemic Arbovirus

2020 ◽  
Vol 65 (1) ◽  
pp. 191-208 ◽  
Author(s):  
Oliver J. Brady ◽  
Simon I. Hay
Keyword(s):  
Invasive Species ◽  
Aedes Aegypti ◽  
Infectious Diseases ◽  
Control Strategies ◽  
Viral Disease ◽  
Rapid Rise ◽  
Disease Vector ◽  
Research Priority ◽  
Global Spread ◽  
Human Habitation

Dengue is an emerging viral disease principally transmitted by the Aedes ( Stegomyia) aegypti mosquito. It is one of the fastest-growing global infectious diseases, with 100–400 million new infections a year, and is now entrenched in a growing number of tropical megacities. Behind this rapid rise is the simple adaptation of Ae. aegypti to a new entomological niche carved out by human habitation. This review describes the expansion of dengue and explores how key changes in the ecology of Ae. aegypti allowed it to become a successful invasive species and highly efficient disease vector. We argue that characterizing geographic heterogeneity in mosquito bionomics will be a key research priority that will enable us to better understand future dengue risk and design control strategies to reverse its global spread.

scholarly journals Facial Injections of Pruritogens and Algogens Excite Partly Overlapping Populations of Primary and Second-Order Trigeminal Neurons in Mice

2010 ◽  
Vol 104 (5) ◽  
pp. 2442-2450 ◽  
Author(s):  
T. Akiyama ◽  
M. Iodi Carstens ◽  
E. Carstens
Keyword(s):  
Sensory Neurons ◽  
Calcium Imaging ◽  
Search Strategy ◽  
Behavioral Responses ◽  
Allyl Isothiocyanate ◽  
Second Order ◽  
The Other ◽  
Trigeminal Neurons ◽  
Population Codes ◽  
Trigeminal Subnucleus Caudalis

Intradermal cheek injection of pruitogens or algogens differentially elicits hindlimb scratching or forelimb wiping, suggesting that these behaviors distinguish between itch and pain. We studied whether pruritogens and algogens excite separate or overlapping populations of primary afferent and second-order trigeminal neurons in mice. Calcium imaging of primary sensory trigeminal ganglion (TG) cells showed that 15.4% responded to histamine, 5.8% to the protease-activated receptor (PAR)-2 agonist, 13.4% to allyl isothiocyanate (AITC), and 36.7% to capsaicin. AITC and/or capsaicin activated the vast majority of histamine- and PAR-2 agonist–sensitive TG cells. A chemical search strategy identified second-order neurons in trigeminal subnucleus caudalis (Vc) responsive to histamine, the PAR-2 agonist, or AITC. A minority of histamine or PAR-2 agonist–responsive Vc neurons responded to the other pruritogen, whereas a large majority of puritogen-responsive Vc neurons responded to capsaicin and/or AITC. A minority of AITC-responsive Vc neurons responded to pruritogens, whereas most responded to capsaicin. These data indicate that most primary and higher-order trigeminal sensory neurons are activated by both pruritic and algesic stimuli, although a minority exhibit selectivity. The results are discussed in terms of population codes for itch and pain that result in distinct behavioral responses of hindlimb scratching and forelimb wiping that are mediated at lumbar and cervical segmental levels, respectively.

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