Agar-polydimethylsiloxane devices for quantitative investigation of oviposition behaviour of adult Drosophila melanogaster

Abstract

Drosophila melanogaster (fruit fly) is a model organism and its behaviours including oviposition (egg-laying) on agar substrates have been widely used for assessment of a variety of biological processes in flies. Physical and chemical properties of the substrate are the dominant factors affecting Drosophila's oviposition, but they have not been investigated precisely and parametrically with the existing manual approaches. As a result, many behavioral questions about Drosophila oviposition, such as the combined effects of the aforementioned substrate properties (e.g., exposure area, sugar content, and stiffness) on oviposition and viability, and their threshold values, are yet to be answered. In this paper, we have devised a simple, easily implementable, and novel methodology that allows for modification of physical and chemical composition of agar substrates in order to quantitatively study survival and oviposition of adult fruit flies in an accurate and repeatable manner. Agar substrates have been modified by surface patterning using single and hexagonally arrayed through-hole polydimethylsiloxane (PDMS) membranes with various diameters and interspacing, as well as by substrate stiffness and sugar content modification via alteration of chemical components. While pure PDMS substrates showed a significant lethal effect on flies, a 0.5 mm diameter through-hole access to agar was found to abruptly increase the survival of adult flies to more than 93%. Flies avoided ovipositing on pure PDMS and on top of substrates with 0.5 mm diameter agar exposure areas. At a hole diameter of 2 mm (i.e., 0.25% exposure area) or larger, eggs were observed to be laid predominately inside the through-holes and along the edges of the PDMS-agar interface, showing a trending increase in site selection with 4 mm (i.e., 1% exposure area threshold) demonstrating natural oviposition rates similar to pure agar. The surfacemodified agar-PDMS hybrid devices and the threshold values reported for the substrate physical and chemical conditions affecting oviposition are novel; therefore, we advocate their use for future in-depth studies of oviposition behaviour in Drosophila melanogaster with accuracy and repeatability. The technique is also useful for development of novel assays for learning and decision-making studies as well as miniaturized devices for self-assembly of eggs and embryonic developmental investigations. V C 2015 AIP Publishing LLC. [http://dx

An integrated hybrid microfluidic device for oviposition-based chemical screening of adult Drosophila melanogaster

“…Young flies that enclosed from the pupae within half a day were collected into new stock bottles and aged for 5 days in the same condition. When transferring flies on the day of the experiment, 25 female and 20 male flies (consistent with our previous work 45 ) were first anesthetized using ether and counted. The flies were given a minimum of 1 hour recovery time prior to each assay.…”

“…We have recently introduced a sensitive miniaturized tool which provided the capability to quantify oviposition behavior of adult stage and free-flying Drosophila in response to physical properties of the substrate. 45 We used PDMS membranes with controlled-size through-holes to pattern laboratory agar substrates with desirable oviposition sites in which the flies showed a strong area-and stiffnessdependent egg laying behavior. This technique has the potential for development of decision making behavioral and toxicological chemical screening devices due to the use of agar, a fly-attractant porous gel, through which chemicals can be infused controllably.…”

“…In this paper, we report the integration of our agar-PDMS oviposition assay tool 45 with microfluidics for controllable and on-chip chemical screening of free-flying fruit flies with oviposition and viability as quantitative readouts of the assay. One major challenge was the integration of agar with patterned PDMS layers, for which a novel ice-based sacrificial layer fabrication technique was successfully devised.…”

Neuroscience Research using Small Animals on a Chip: From Nematodes to Zebrafish Larvae

“…Research performed by researchers showed how fruit fly larvae respond to heavy metals present in food [69]. A group of researchers studied oviposition (i.e., egg-laying) of the adult fruit fly [7,70]. Adult fruit fly has also been studied for observing how they and choose and approach the path for the food [7,57].…”

A microfluidic device to study electrotaxis and dopaminergic system of zebrafish larvae

“…Microfluidic technology has recently emerged as a powerful tool for neural and behavioral investigation of small model organisms such as C. elegans, [35][36][37][38][39][40][41][42] D. melanogaster, [43][44][45][46] and D. rerio. [47][48][49][50][51][52][53] Most recently, various microfluidic techniques have been introduced for precise manipulation, stimulation, and monitoring of zebrafish larvae's behavior.…”