Studying Mitochondrial Structure and Function in Drosophila Ovaries

Summary

Analysis of the mitochondrial structure-function relationship is required for a thorough understanding of the regulatory mechanisms of mitochondrial functionality. Specific methods for studying mitochondrial structure and function in live and fixed Drosophila ovaries are described and demonstrated in this paper.

Abstract

Analysis of the mitochondrial structure-function relationship is required for a thorough understanding of the regulatory mechanisms of mitochondrial functionality. Fluorescence microscopy is an indispensable tool for the direct assessment of mitochondrial structure and function in live cells and for studying the mitochondrial structure-function relationship, which is primarily modulated by the molecules governing fission and fusion events between mitochondria. This paper describes and demonstrates specific methods for studying mitochondrial structure and function in live as well as in fixed tissue in the model organism Drosophila melanogaster. The tissue of choice here is the Drosophila ovary, which can be isolated and made amenable for ex vivo live confocal microscopy. Furthermore, the paper describes how to genetically manipulate the mitochondrial fission protein, Drp1, in Drosophila ovaries to study the involvement of Drp1-driven mitochondrial fission in modulating the mitochondrial structure-function relationship. The broad use of such methods is demonstrated in already-published as well as in novel data. The described methods can be further extended towards understanding the direct impact of nutrients and/or growth factors on the mitochondrial properties ex vivo. Given that mitochondrial dysregulation underlies the etiology of various diseases, the described innovative methods developed in a genetically tractable model organism, Drosophila, are anticipated to contribute significantly to the understanding of the mechanistic details of the mitochondrial structure-function relationship and to the development of mitochondria-directed therapeutic strategies.

Introduction

Mitochondria are classically described as the cellular powerhouse, since they are the main seats of energy production in differentiated cells. Moreover, mitochondria play a critical role in metabolism, heat generation, lipid modification, calcium and redox homeostasis, the orchestration of cell signaling processes, etc¹. Mitochondria also play an active role in the induction of cell death², as well as in cell cycle regulation³. Such multi-functionality raises the following fundamental questions: a) how do mitochondria perform all these functions simultaneously and b) are there specific mitochondrial pools or subzones that are ....

Protocol

1. Preparation of Drosophila (the tools required are depicted in Figure 2A)

1. For any of the experiments described, collect Drosophila (maintained at room temperature, or 25 ºC) within 5 days of eclosion and place them in a vial filled with 5 - 7 mL of Drosophila food (see Materials Table), with no more than 25 flies in each vial; maintain a female:male ratio of 2:1.
2. Sprinkle a small amount of granulated yeast to stimulate Drosophila egg production. Perform experimental manipulation within 2 - 4 days.

2. Dissection of Drosophila Ovaries (the tools re....

Results

The described methods can be used to study mitochondrial structure and function in live and fixed Drosophila ovaries (Figure 2B). Provided are some examples of anticipated results obtained with the described methods.

Dissection of the Drosophila ovary: When dissected further, the severed abdomens (Figure 3B) from the whole Drosophila (Figure 3A).......

Discussion

Critical Steps within the Protocol

Photobleaching: Preventing undue photobleaching of fluorescent samples is absolutely necessary to performing efficient confocal microscopy. Therefore, the time used to locate samples through the eyepiece or to set image acquisition parameters through the live scanning mode should be minimized to minimize photobleaching.

Tissue damage: Since mitochondria are considered to be the sensors of cellular health, it.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Grace's Media (Insect Dissecting Medium)	Fisher Scientific	30611031-2
41 Paraformaldehyde AQ	Electronic Microscopy Sciences	50-259-99
Mitotracker Green (overall mitochondrial stain)	Life Technologies	m7514	Reconstitute and Aliquot
Tetramethylrhodamine ethyl ester perchlorate	Sigma Aldrich	87917-25MG	Reconstitute and Aliquot
MitoSox (Mito-Ros stain)	Life Technologies	m36008	Reconstitute and Aliquot
PolyLysine	MP Biomedicals	ICN15017625
Fly Vials	Fisher Scientific	AS-515
Fly Conicals	Fisher Scientific	AS-355
Fly Vial Flugs	Fisher Scientific	AS273
Fly Conical Flugs	Fisher Scientific	AS 277
Jazzmix Drosophila food (Drosophila food)	Fisher Scientific	AS153
Bovine Serum Albumin	Sigma Aldrich	A9647-50G
Cyclin E Antibody (d-300)	Santa Cruz	sc- 33748
ATPB antibody [3D5] - Mitochondrial Marker	AbCam	ab14730
Cy3 AffiniPure Goat Anti-Mouse IgG (H+L)	Jackson ImmunoResearch	115-165-146
Cy5 AffiniPure Goat Anti-Rabbit IgG (H+L)	Jackson ImmunoResearch	111-175-144
Hoechst	Fisher Scientific	H3570
VectaShield	Fisher Scientific	H100
Azer Scientific EverMark Select Microscope Slides	Fisher Scientific	22-026-252
Microscope Cover Glass	Fisher Scientific	12-542-B
Mat Tek Corp Glass Bottom Mircrowell Dish	Fisher Scientific	P35G-0-14-C
Active Dried Yeast	Fisher Scientific	ICN10140001
Confocal Microscope	Carl Zeiss	LSM 700
Dumont #5 Forceps	Fine Science Technologies	11251-20
Moria Nickel Plated Pin Holder	Fine Science Technologies	26016-12
Minutien Pins	Fine Science Technologies	26002-15
MYFP ( w[*]; P{w[+mC]=sqh-EYFP-Mito}3 )	Bloomington Stock Center	7194
Fly Pad	Fly stuff	59-118
Blowgun	Fly stuff	54-104
Blowgun needle	Flystuff	54-119
Dissecting Microscope	Carl Zeiss	Stemi 2000
Analyses software	Carl Zeiss	Zen
Analyses software	Open source	Image J
Research Macro Zoom Microscope	Olympus	MVX10
QICAM Fast 1394 Cooled Digital Camera, 12-bit, Mono	QImaging	QIC-F-M-12-C
QCapture Pro 5.1	QImaging