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(Circulation. 2006;114:e35-e36.)
© 2006 American Heart Association, Inc.

Images in Cardiovascular Medicine

In Vivo Imaging of the Adult Drosophila melanogaster Heart With Real-Time Optical Coherence Tomography

Michael A. Choma, PhD; Susan D. Izatt, MD; Robert J. Wessells, PhD; Rolf Bodmer, PhD; Joseph A. Izatt, PhD

From the Departments of Biomedical Engineering (M.A.C., J.A.I.) and Pediatrics (S.D.I.), Duke University, Durham, NC, and The Burnham Institute (R.J.W., R.B.), La Jolla, Calif.

Correspondence to Michael A. Choma, PhD, Department of Biomedical Engineering, Duke University, 136 Hudson Hall, PO Box 90281, Durham, NC 27708–0281. Email mac32{at}duke.edu

Over the past century, research involving the fruit fly Drosophila melanogaster has consistently yielded fundamental insights into the nature of complex organisms. The cardiovascular sciences have benefited from these discoveries. Examples include the discovery of the human ether-a-go-go inward rectifying potassium channel, a fly homologue of HERG that is implicated in inherited long-QT syndrome, and the tinman protein, a fly homologue of NKX2.5 that is responsible for certain congential atrial septal defects and conduction abnormalities. More recent results, such as those involving the insulin regulation of heart function in aging fruit flies, suggest that D melanogaster is an emerging model organism in cardiac disease. To date, functional studies of the adult D melanogaster heart have been difficult, and in vivo cross-sectional imaging has been essentially impossible. Here, we present real-time in vivo B- and M-mode optical coherence tomography (OCT) images of wild-type (OreR) D melanogaster heat tubes. Our OCT system has axial and lateral resolution of 10 µm and 23 µm, respectively, a B-mode frame rate of 8 to 20 per second, and an M-mode line rate of 4000 per second. Flies were anesthetized with FlyNap (Carolina Biological, Burlington, NC) for examination. Numbered figures represent different flies. Figure 1 and Movies I and II show transverse and sagittal B-scans of the heat tube during systole and diastole. M-mode images were taken at the landmark indicated by the line in Figure 1C. Figure 2 shows a 1-second M-scan. From the M-scan, the heart rate is determined to be 360 beats per minute (beat-to-beat interval of 167 milliseconds), and the shortening fraction to be 67%. Figure 3 and Movie III show intermittent arrhythmia and asystole occasionally noted immediately after induction of anesthesia. These images suggest that D melanogaster can be readily used as a model organism in genetic and genomic studies of cardiovascular disease including heart failure and arrhythmia.

View larger version (108K): [in this window] [in a new window]   Figure 1. Transverse (A, B) and sagittal (C, D) real-time OCT images of D melanogaster dorsal heart tube of the anterior abdomen in diastole (A, C) and systole (B, D). The solid arrow points to the conical chamber in the anterior portion of the abdomen, wheras the dashed arrow points to distal portions of the heart tube. The vertical line marked by m indicates the location of M-mode image acquisition. The inset in B shows the heart tube at 2x image magnification. Scale bars=100 µm.

View larger version (118K): [in this window] [in a new window]   Figure 2. A, M-mode image of dorsal heart tube taken over 1 second. This image is composed of 4000 A lines. The heart completes 6 cardiac cycles over the course of this second (heart rate=360 bpm). B and C are 68-ms segments of A when the heart tube is in diastole and systole, respectively. These scans indicate that the diameter of the tube changes by a factor of 3 when contracting. This corresponds to a shortening fraction of 67% at the position indicated in Figure 1C.

View larger version (81K): [in this window] [in a new window]   Figure 3. Arrhythmia in D melanogaster observed with M-mode imaging. A, Heart tube is in asystole for the first 400 ms, after which regular rhythm is resumed. B, Irregular rate present at 0 ms and 750 ms.

	Acknowledgments

 
Sources of Funding

This work was supported by National Institutes of Health grant R24-EB00243, "Partnership for Research in Optical Coherence Tomography."

Disclosures

Dr J. Izatt is a cofounder, officer, and major stockholder in Bioptigen, Inc, which has commercialized an advanced version of the instrument used in this study. Duke University has licensed intellectual property to and holds equity in Bioptigen, Inc.

	Footnotes

 
The online-only Data Supplement, which contains 3 movies, can be found at http://circ.ahajournals.org/cgi/content/full/114/2/e35/DC1.

This Article Full Text (PDF) Data Supplement Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Choma, M. A. Articles by Izatt, J. A. Search for Related Content PubMed PubMed Citation Articles by Choma, M. A. Articles by Izatt, J. A. Related Collections Contractile function Animal models of human disease Arrythmias-basic studies Imaging Arrhythmias, clinical electrophysiology, drugs