Papers by Carolina Reisenman
Science, 2022
For more than 100 years, the fruit fly Drosophila melanogaster has been one of the most studied m... more For more than 100 years, the fruit fly Drosophila melanogaster has been one of the most studied model organisms. Here, we present a single-cell atlas of the adult fly, Tabula Drosophilae , that includes 580,000 nuclei from 15 individually dissected sexed tissues as well as the entire head and body, annotated to >250 distinct cell types. We provide an in-depth analysis of cell type–related gene signatures and transcription factor markers, as well as sexual dimorphism, across the whole animal. Analysis of common cell types between tissues, such as blood and muscle cells, reveals rare cell types and tissue-specific subtypes. This atlas provides a valuable resource for the Drosophila community and serves as a reference to study genetic perturbations and disease models at single-cell resolution.
known as kissing bugs, are a potential health problem in the southwestern United States as possib... more known as kissing bugs, are a potential health problem in the southwestern United States as possible vectors of Trypanosoma cruzi, the causative agent of Chagas disease. Although this disease has been traditionally restricted to Latin America, a small number of vector-transmitted autochthonous US cases have been reported. Because triatomine bugs and infected mammalian reservoirs are plentiful in southern Arizona, we collected triatomines inside or around human houses in Tucson and analyzed the insects using molecular techniques to determine whether they were infected with T. cruzi. We found that 41.5 % of collected bugs (n = 164) were infected with T. cruzi, and that 63 % of the collection sites (n = 22) yielded>1 infected specimens. Although many factors may contribute to the lack of reported cases in Arizona, these results indicate that the risk for infection in this region may be higher than previously thought.
ABSTRACTThe diversity of herbivorous insects is attributed to their propensity to specialize on t... more ABSTRACTThe diversity of herbivorous insects is attributed to their propensity to specialize on toxic plants. In an evolutionary twist, toxins betray the identity of their bearers when herbivores co-opt them as cues for host-plant finding, but the mechanisms underlying this process are poorly understood. We focused onScaptomyza flava, an herbivorous drosophilid specialized on isothiocyanate (ITC)-producing (Brassicaceae) plants, and identifiedOr67bparalogs that were triplicated as mustard-specific herbivory evolved. Using heterologous systems for the expression of olfactory receptors, we found thatS. flavaOr67bs, but not homologs from microbe-feeding relatives, responded selectively to ITCs, each paralog detecting different ITC subsets. Consistent with this,S. flavawas attracted to ITCs, as wasDrosophila melanogasterexpressingS. flavaOr67b3 in the homologousOr67bolfactory circuit. Thus, our results show that plant toxins were likely co-opted as olfactory attractants through gene dup...
Frontiers in Physiology, 2016
Harmful insects include pests of crops and storage goods, and vectors of human and animal disease... more Harmful insects include pests of crops and storage goods, and vectors of human and animal diseases. Throughout their history, humans have been fighting them using diverse methods. The fairly recent development of synthetic chemical insecticides promised efficient crop and health protection at a relatively low cost. However, the negative effects of those insecticides on human health and the environment, as well as the development of insect resistance, have been fueling the search for alternative control tools. New and promising alternative methods to fight harmful insects include the manipulation of their behavior using synthetic versions of "semiochemicals", which are natural volatile and non-volatile substances involved in the intra-and/or inter-specific communication between organisms. Synthetic semiochemicals can be used as trap baits to monitor the presence of insects, so that insecticide spraying can be planned rationally (i.e., only when and where insects are actually present). Other methods that use semiochemicals include insect annihilation by mass trapping, attract-and-kill techniques, behavioral disruption, and the use of repellents. In the last decades many investigations focused on the neural bases of insect's responses to semiochemicals. Those studies help understand how the olfactory system detects and processes information about odors, which could lead to the design of efficient control tools, including odor baits, repellents or ways to confound insects. Here we review our current knowledge about the neural mechanisms controlling olfactory responses to semiochemicals in harmful insects. We also discuss how this neuroethology approach can be used to design or improve pest/vector management strategies.
Journal of insect physiology, 2014
Blood-sucking insects strongly rely on olfactory cues to find their vertebrate hosts. As in other... more Blood-sucking insects strongly rely on olfactory cues to find their vertebrate hosts. As in other insects with different lifestyles, it has been shown that endogenous and exogenous factors modulate olfactory responses. The triatomine bug Rhodnius prolixus is an important vector of Chagas disease and a classical model for studies of physiology and behavior. In this species, the behavioral response to host-derived odorants is modulated by both the time of the day and the starvation. Here I investigated the peripheral neural mechanisms underlying these modulatory effects. For this, I measured the electroantennogram (EAG) responses of insects towards different concentrations (from 0.5% to 75% vol/vol) of an attractive host-odorant, ammonia. I tested the responses of starved and fed animals during the middle of the day (when insects are inactive and aggregated in refuges) and at the beginning of the night (when insects become active and search for hosts). Regardless of the time of the da...
Vision Research, 2003
Two types of transient responses have been investigated in fly motion-sensitive neurons in the pa... more Two types of transient responses have been investigated in fly motion-sensitive neurons in the past: the impulse and the step response. In response to a brief motion pulse, cells show a sudden rise in activity followed by an exponential decay (Ôimpulse re-sponseÕ). In response to the onset of a constant velocity stimulus, cells exhibit transient oscillations before settling to a steady-state value (Ôstep responseÕ). Since the impulse response has been shown to shorten when tested after presentation of an adapting motion stimulus, we investigated whether adaptation also occurs during the step response. We tested this hypothesis by recording extracellularly the response of the H1-cell in the lobula plate of the blowfly Calliphora vicina to gratings of varying pattern contrasts and drift velocity. We found that the transient oscillations of the step response strongly depend on the pattern contrast: at low contrasts, oscillations lasted for several seconds, whereas at high contrasts, they settled within fractions of a second. This suggests that motion adaptation occurs during the initial period of the stimulus presentation and is dependent on the contrast of the motion stimulus. Using identical stimulus parameters (contrast and temporal frequency) for the adapting stimulus and testing the impulse response afterwards, we found that the impulse response and the transient period in the step response shortened in a similar way. We then analyzed the dynamic of the transients oscillations produced by ongoing motion of a square wave pattern in the antipreferred direction (null direction) of H1. As observed for preferred direction motion, we found that the duration and amplitude of those transients shortened as the contrast and the velocity of the pattern increased, and that the oscillations disappeared when a blank screen instead of a pattern was presented before the onset of motion. Under both stimulus conditions, i.e. grating and blank screen before motion onset, the steady-state response level showed the same dependence on the contrast and temporal frequency of the pattern. When we analyzed the responses of the cell to pattern of various sizes and contrasts moving in the preferred direction of the cell, we found that increments in the size affected the overall amplitude of both the transient oscillations and the steady-state response level, whereas the duration of the oscillations only depended on the local pattern contrast. We also tested the impulse response before and after the presentation of an adapting stimulus presented in either the same or a different location of the visual field. The response shortened only when both the adapting and the test stimuli were presented at the same location. These last experiments demonstrate a strictly local mechanism of adaptation affecting the response transients of both the impulse and the step response.
PLoS ONE, 2011
Bursting as well as tonic firing patterns have been described in various sensory systems. In the ... more Bursting as well as tonic firing patterns have been described in various sensory systems. In the olfactory system, spontaneous bursts have been observed in neurons distributed across several synaptic levels, from the periphery, to the olfactory bulb (OB) and to the olfactory cortex. Several in vitro studies indicate that spontaneous firing patterns may be viewed as ''fingerprints'' of different types of neurons that exhibit distinct functions in the OB. It is still not known, however, if and how neuronal burstiness is correlated with the coding of natural olfactory stimuli. We thus conducted an in vivo study to probe this question in the OB equivalent structure of insects, the antennal lobe (AL) of the tobacco hornworm Manduca sexta. We found that in the moth's AL, both projection (output) neurons (PNs) and local interneurons (LNs) are spontaneously active, but PNs tend to produce spike bursts while LNs fire more regularly. In addition, we found that the burstiness of PNs is correlated with the strength of their responses to odor stimulation-the more bursting the stronger their responses to odors. Moreover, the burstiness of PNs was also positively correlated with the spontaneous firing rate of these neurons, and pharmacological reduction of bursting resulted in a decrease of the neurons' responsiveness. These results suggest that neuronal burstiness reflects a physiological state of these neurons that is directly linked to their response characteristics.
Light-induced and circadian changes in the compound eye of the haematophagous bug Triatoma infest... more Light-induced and circadian changes in the compound eye of the haematophagous bug Triatoma infestans (Hemiptera: Reduviidae)
Journal of Insect Physiology, 1998
In addition to compound eyes, most adult insects posses two or three simple eyes, the ocelli. The... more In addition to compound eyes, most adult insects posses two or three simple eyes, the ocelli. The function of these photoreceptors remains elusive in most cases. Triatomine bugs posses two well-developed ocelli, located in a latero-dorsal position, behind the compound eyes. We tested the role of the ocelli in the phototactic behaviour of Triatoma infestans, by measuring the time spent by adult males in the dark half of an experimental arena, which had the other half illuminated. The occlusion of the ocelli or the compound eyes alone had little effect on the phototactic response of the bugs. Only those insects which had both their ocelli and compound eyes occluded showed a significant reduction in their negative response to light. The ability of the ocelli of T. infestans to mediate the phototactic response by themselves (i.e., not through the modulation of compound eyes sensitivity) constitutes the first report on this function in insects.
The Journal of Experimental Biology
Insects use multiple sensory modalities when searching for and accepting a food source, in partic... more Insects use multiple sensory modalities when searching for and accepting a food source, in particular odor and taste cues. Food-derived odorants are generally involved in mediating long-and short-range attraction. Taste cues, on the other hand, act directly by contact with the food source, promoting the ingestion of nutritious food and the avoidance of toxic substances. It is possible, however, that insects integrate information from these sensory modalities during the process of feeding itself. Here, using a simple feeding assay, we investigated whether odors modulate food consumption in the fruit fly Drosophila melanogaster. We found that the presence of both single food-derived odorants and complex odor mixtures enhanced consumption of an appetitive food. Feeding enhancement depended on the concentration and the chemical identity of the odorant. Volatile cues alone were sufficient to mediate this effect, as feeding was also increased when animals were prevented from contacting th...
Emerg Infect Dis, 2010
Triatomine insects (Hemiptera: Reduviidae), commonly known as kissing bugs, are a potential healt... more Triatomine insects (Hemiptera: Reduviidae), commonly known as kissing bugs, are a potential health problem in the southwestern United States as possible vectors of Try- panosoma cruzi, the causative agent of Chagas disease. Although this disease has been traditionally restricted to Latin America, a small number of vector-transmitted autoch- thonous US cases have been reported. Because triatom- ine bugs and infected
Current knowledge of the olfactory system of Manduca sexta is discussed within the context of the... more Current knowledge of the olfactory system of Manduca sexta is discussed within the context of the natural history of this model organism. The anatomy of the olfactory system is described progressing from the antennas to the antennal lobes and then to higher centers of olfactory processing in the brain. The principles of olfactory information processing revealed from studies of this organism are discussed with respect to its ability to identify odors and evaluate their concentration and spatiotemporal dynamics. The cellular substrate underlying multiple functional roles of antennal lobe circuitry is also described.
Se estudiaron algunas propiedades del sistema visual de la vinchuca Triatoma infestans. La cuanti... more Se estudiaron algunas propiedades del sistema visual de la vinchuca Triatoma infestans. La cuantificacion de la respuesta fototactica negativa de este insecto permitio: 1) establecer el umbral de sensibilidad de la respuesta a la luz blanca (<0.009 μW/cm²);2) demostrar que esta respuesta muestra una variacion diaria, siendo mucho mayor durante [...]
The negative phototactic response of Triatoma infestans (Hemiptera) was studied in an arena, half... more The negative phototactic response of Triatoma infestans (Hemiptera) was studied in an arena, half of which was kept dark and the other half illuminated with dierent light intensitites. For each intensity we measured the time the insects spent in the dark half, the time to reach the side opposite to that where they were released, and the number of passages through the middle line of the arena. T. infestans displayed a photonegative behaviour that was enhanced by high light intensities. Bugs maintained in 12:12 light-dark cycles responded dierently to the same illumination levels when tested in their photophase and scotophase: sensitivity to light was higher during the latter. Bugs entrained to light-dark cycles, kept afterwards either in constant darkness or in constant light, and tested in their subjective night and day, showed the same responses as bugs from the lightdark group tested in their corresponding photophase and scotophase. Thus, phototactic sensitivity is under endogenous control. The behaviour shown by T. infestans may be understood as being composed of at least two dierent drives: an exploratory one, and a negative phototactic response that is under endogenous control and is particularly sensitive to light during the scotophase, when activity peaks occur.
Frontiers in Physiology, 2015
Understanding how animals make use of environmental information to guide behavior is a fundamenta... more Understanding how animals make use of environmental information to guide behavior is a fundamental problem in the field of neuroscience. Similarly, the field of ecology seeks to understand the role of behavior in shaping interactions between organisms at various levels of organization, including population-, community-and even ecosystem-level scales. Together, the newly emerged field of "Neuroecology" seeks to unravel this fundamental question by studying both the function of neurons at many levels of the sensory pathway and the interactions between organisms and their natural environment. The interactions between herbivorous insects and their host plants are ideal examples of Neuroecology given the strong ecological and evolutionary forces and the underlying physiological and behavioral mechanisms that shaped these interactions. In this review we focus on an exemplary herbivorous insect within the Lepidoptera, the giant sphinx moth Manduca sexta, as much is known about the natural behaviors related to host plant selection and the involved neurons at several level of the sensory pathway. We also discuss how herbivore-induced plant odorants and secondary metabolites in floral nectar in turn can affect moth behavior, and the underlying neural mechanisms.
Journal of insect physiology, Jan 10, 2016
Although kissing bugs (Triatominae: Reduviidae) are perhaps best known as vectors of Chagas disea... more Although kissing bugs (Triatominae: Reduviidae) are perhaps best known as vectors of Chagas disease, they are important experimental models in studies of insect sensory physiology, pioneered by the seminal studies of Wigglesworth and Gillet more than eighty years ago. Since then, many investigations have revealed that the thermal, hygric, visual and olfactory senses play critical roles in the orientation of these blood-sucking insects towards hosts. Here we review the current knowledge about the role of these sensory systems, focussing on relevant stimuli, sensory structures, receptor physiology and the molecular players involved in the complex and cryptic behavioural repertoire of these nocturnal insects. Odours are particularly relevant, as they are involved in host search and are used for sexual, aggregation and alarm communication. Tastants are critical for a proper recognition of hosts, food and conspecifics. Heat and relative humidity mediate orientation towards hosts and are ...
F1000 - Post-publication peer review of the biomedical literature, 2000
F1000 - Post-publication peer review of the biomedical literature, 2000
Ann N Y Acad Sci, 2009
Olfactory cues play decisive roles in the lives of most insect species, providing information abo... more Olfactory cues play decisive roles in the lives of most insect species, providing information about biologically relevant resources, such as food, mates, and oviposition sites. The nocturnal moth Manduca sexta feeds on floral nectar from a variety of plants (and thus serves as a pollinator), but females oviposit almost exclusively on solanaceous plants, which they recognize on the basis of olfactory cues. Plants, however, respond to herbivory by releasing blends of volatiles that attract natural enemies of herbivores. Thus, oviposition behavior probably results from the sensory evaluation not only of attractive host plant volatiles but also of repellent volatiles that indicate the acceptability or inappropriateness, respectively, of host plants for the females' offspring. Here we describe results from chemical-ecological, neurophysiological, and behavioral experiments aimed at understanding the neural mechanisms that control oviposition behavior in M. sexta.
F1000 - Post-publication peer review of the biomedical literature, 2008
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Papers by Carolina Reisenman