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Localized microinjection of intact Drosophila melanogaster larva to investigate the effect of serotonin on heart rate. | LitMetric

Localized microinjection of intact Drosophila melanogaster larva to investigate the effect of serotonin on heart rate.

Lab Chip

Department of Mechanical Engineering, York University, BRG 433B, 4700 Keele St, Toronto, ON M3J 1P3, Canada.

Published: January 2020

AI Article Synopsis

  • The paper introduces a new hybrid microfluidic device designed for localized microinjection and heart monitoring in intact Drosophila melanogaster larvae, focusing on their use as a model for studying cardiac disorders.
  • This device addresses previous limitations in research by allowing delicate handling, controlled chemical microinjections, and the ability to conduct post-treatment studies without sacrificing the larvae.
  • Using a MATLAB-based technique, the study demonstrates how serotonin injection affects the heart rate of Drosophila larvae, showing significant increases in heart rates at specific concentrations and volumes.

Article Abstract

In this paper, we present a novel hybrid microfluidic device for localized microinjection and heart monitoring of intact Drosophila melanogaster larvae at different developmental stages. Drosophila heart at the larval stage has been used as a model for cardiac disorder studies. However, previous pharmacological and toxicological cardiac studies are limited to dissected (semi-intact) Drosophila larvae which cannot be used for post-treatment studies. Challenges associated with microinjection of intact larvae include delicate handling of individual larvae, proper orientation for microneedle penetration, localized microinjection with controlled amount of chemicals into the hemolymph and reversible immobilization for post-injection phenotypic studies, all addressed by our microfluidic device. Larva loading and orientation were achieved by glass capillaries integrated into the PDMS microfluidic device. Side suction channels were used for immobilization prior to heart activity recording. Localized microinjection was achieved with a one degree-of-freedom microneedle and a custom-made pressure driven reagent delivery system, without any adverse effect on heart rate and animal viability. Precision in localized injection into the body cavity close to the heart chamber or the fat body was demonstrated with our microfluidic device. A MATLAB-based heartbeat quantification technique was used to investigate the dose-dependent effect of serotonin (5-hydroxytryptamine), a neurotransmitter, on the heart rate of intact Drosophila larvae, for the first time. Injection of 40 nL serotonin with ≥0.01 mM concentration significantly increased the heart rate of 3 instar larvae by 21 ± 7% (SEM). Injection of 5 nL serotonin with a concentration of 0.01 mM significantly increased the heart rate of 2 instar larvae by 12 ± 3% (SEM). The proposed microfluidic injection and heartbeat monitoring technique can be used for dye angiography and hemolymph circulation studies as well as screening intravenous drugs in vivo using the whole-animal Drosophila melanogaster.

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Source
http://dx.doi.org/10.1039/c9lc00963aDOI Listing

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