Biology subjects

Giraldo, D.

Publications and source records attributed to Giraldo, D..

4 recordsLinked to original sources

bioRxiv2023

A neurogenetic toolkit to decode Anopheles gambiae olfaction

The African malaria mosquito Anopheles gambiae exhibits a strong innate sensory drive to seek out human scent. To detect human odorants, An. gambiae uses olfactory sensory neurons (OSNs) that can be divided into different classes by unique repertoires of chemoreceptor gene expression. We applied CRISPR-Cas9-mediated T2A-In Frame Fusions and the QF2/QUAS system to gain genetic access to specific OSN subsets in An. gambiae expressing the chemoreceptor genes Ir25a, Ir76b, Gr22 and orco. We first optimized methods to generate cell-type specific QF2 driver and QUAS responder lines to map expression patterns of these chemoreceptors across mosquito sensory appendages. We next applied transcuticular calcium imaging to record neurophysiological responses to select human-related odorants for each OSN class. This neurogenetic toolkit tiling OSN subsets in An. gambiae, including those responsive to CO2, stands to support systematic efforts to decode olfaction in this prolific disease vector at high-resolution to combat malaria.

neuroscience↗

bioRxiv2022

A semi-field system for quantifying Anopheles gambiae attraction to human scent

Variability in the chemical composition of human scent has the potential to modulate mosquito attraction to certain humans. We have engineered a large-scale, semi-field system in Zambia for quantifying mosquito olfactory preferences towards whole body odor sourced from different humans under naturalistic conditions. In a flight cage arena with infrared tracking, we document that the African malaria mosquito Anopheles gambiae hierarchically prefers to land on heated targets mimicking human skin temperature when they are baited with carbon dioxide (CO2) over background air, human body odor over CO2, and the scent of one individual over another. In a six-choice assay configuration, we further identify humans at both ends of the attractiveness spectrum whose scent is differentially attractive to An. gambiae relative to other individuals. We demonstrate integrative use of this multi-choice olfactory assay with whole body volatilomics, establishing a powerful method for discovery of human odorants modulating heterogeneity in biting risk at enhanced throughput.

animal behavior and cognition↗

bioRxiv2020

Synergistic Coding of Human Odorants in the Mosquito Brain

The yellow fever mosquito Aedes aegypti employs olfaction to locate humans. We applied neural activity mapping to define the molecular and cellular logic of how the mosquito brain is wired to detect two human odorants that are attractive when blended together. We determined that the human breath volatile carbon dioxide (CO2) is detected by the largest unit of olfactory coding in the antennal lobe of the mosquito brain. Synergistically, CO2 detection gates pre-synaptic calcium signaling in olfactory sensory neuron axon terminals that innervate unique antennal lobe regions tuned to the human sweat odorant L-(+)-lactic acid. We propose that simultaneous detection of the signature human volatiles CO2 and L-(+)-lactic acid disinhibits a multimodal olfactory network for hunting humans in the mosquito brain.

neuroscience↗

bioRxiv2018

Cold trapped - Correcting locomotion dependent observation biases in thermal preference of Drosophila

Sensing environmental temperatures is essential for the survival of ectothermic organisms. In Drosophila, two methodologies are used to study temperature preferences (TP) and the genes involved in thermosensation: two-choice assays and temperature gradients. Whereas two-choice assays reveal a relative TP, temperature gradients can identify the absolute Tp. One drawback of gradients is that small ectothermic animals are susceptible to cold-trapping: a physiological inability to move at the cold area of the gradient. Often cold-trapping cannot be avoided, biasing the resulting TP to lower temperatures. Two mathematical models were previously developed to correct for cold-trapping. These models, however, focus on group behaviour which can lead to overestimation of cold-trapping due to group aggregation. Here we present a mathematical model that estimates the behaviour of individual Drosophilain temperature gradients. The model takes the spatial dimension and temperature difference of the gradient into account, as well as the rearing temperature of the flies. Furthermore, it allows quantifying cold-trapping, reveals true TP, and differentiates between temperature preference and tolerance. Online simulation is hosted at http://igloo.uni-goettingen.de. The code can be accessed at https://github.com/zerotonin/igloo.

neuroscience↗