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Biologically Inspired Biosensors from Fish Chromatophores Redacted for Privacy Abstract Approved AN ABSTRACT OF THE THESIS OF Tonga R. Danoskv for the degree of Master of Science in Biochemistry and Biophysics presented on July 12, 1996. Title: Biologically Inspired Biosensors from Fish Chromatophores Redacted for Privacy Abstract approved: Philip N. McFadden This thesis explores the feasibility of using melanophore-based biosensors from Oreochromis niloticus. Melanophores are one type of pigmented cell of the scales and fins of fish that respond in a motile fashion to a diverse range of stimuli. Fish scales were employed as the first step in determining the utility of melanophores as biosensors. Responsiveness of melanophores in scales was quantitated with several bioactive agents. Experiments with depolarizing potassium ion, guanethidine, yohimbine (an adrenergic antagonist), and capsaicin (a sensory stimulant) provided evidence that melanophores are under nervous regulation. Conditions were developed to allow simplification of intact scale preparations, entailing epidermal removal and dennervation of scales. This simplification resulted in increased sensitivity and responsiveness to a larger array of bioactive agents, including a cyclic AMP analog. The simplified preparation was successfully tested for its ability to function as a biosensor using pharmaceutical eye drops; the response observed was determined to be due to naphazoline, an adrenergic agonist. Methods were developed that enabled culturing of chromatophores independent from scales. Cultured chromatophores were found to be responsive to bioactive agents with a comparable degree of sensitivity as simplified scale preparations. Attempts were undertaken to develop co-cultures of chromatophores with other cell types and with further development melanophore-based biosensors can be exploited. 'Copyright by Tonya R. Danosky July 12, 1996 All Rights Reserved Biologically Inspired Biosensors from Fish Chromatophores by Tonya R. Danosky A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science Completed July 12, 1996 Commencement June, 1997 Master of Science thesis of Tonya R. Danoskv presented on July 12, 1996 APPROVED: Redacted for Privacy Major Profes or, representing Biochemistry and Biophysics Redacted for Privacy Chair of De artment of Biochemistry and Biophysics Redacted for Privacy Dean of Grad e School I understand that my thesis will become part of the permanent collection of Oregon State University libraries. My signature below authorizes release of my thesis to any reader upon request. Redacted for Privacy Tonya R. Da sky, Author ACKNOWLEDGMENTS I would like to thank everyone who has helped me reach this step in my education. I would especially like to thank Darin Weber and Phil Gafken for all of their input, advice, and help over the past years. I would also like to thank my advisor, Phil McFadden, for his help and guidance throughout this project. I would like to give my appreciation and thanks to my family, Cheryl Kula, Tom Brooks, and Lisa Brooks, for their encouragement and support throughout my graduate education. I would also like to thank my husband, Tim Danosky, who has supported and motivated me throughout this research and who's opinion and insight I value greatly. TABLE OF CONTENTS Page 1. INTRODUCTION 1 1.1 Introduction 1 1.2 Background 2 1.2.1 The system 2 1.2.2 Attributes of a biosensor based on fish chromatophores 8 1.3 Conclusion 10 2. THE INTACT TISSUE: THE SCALE 11 2.1 Introduction 11 2.2 Materials and Methods 12 2.2.1 Scale removal 12 2.2.2 Visualization of scales and chromatophores 12 2.2.3 Quantification of melanophore activity 13 2.2.4 Pharmacological studies using scales 16 2.3 Results 17 2.3.1 Nervous system regulation of chromatophores 17 2.3.2 Chromatophore survivability: Is spontaneous aggregation due to chromatophore loss of viability in an excised tissue? 25 2.3.3 Biosensors exploiting the receptor regulation of chromatophore activity 30 2.3.4 Integration of multiple regulatory systems 34 2.3.5 Evidence for melanophore coupling: Pigment quivering 36 2.3.6 Sensory nerves in freshly isolated intact scales 39 2.4 Discussion 47 3. THE REDUCED TISSUE 50 3.1 Introduction 50 TABLE OF CONTENTS (Continued) Page 3.2 Materials and Methods: Skinning of isolated scales 50 3.3 Results 51 3.3.1 Can a second messenger be used to elicit a response in chromatophores 51 3.3.2 Dennervation 52 3.3.3 Are sensory nerves present in skinned scales? 53 3.3.4 Skinned scale responsiveness 53 3.4 Discussion 56 4. CHROMATIC RESPONSES OF ISOLATED CHROMATOPHORES 61 4.1 Introduction 61 4.2 Materials and Methods 61 4.2.1 Melanophore culture 61 4.2.2 Pharmacological studies using isolated chromatophores 63 4.2.3 Cerebellar culture 64 4.3 Results 65 4.3.1 Responses of isolated chromatophores 65 4.3.2 Co-culturing to reconstitute cell-cell communication 69 4.3.3 Using the isolation procedure with other fish 70 4.4 Discussion 71 5. CONCLUSION 73 BIBLIOGRAPHY 76 APPENDIX: Biosensors based on the chromatic activities of living, naturally pigmented cells: digital image processing of the dynamics of fish melanophores 79 A 1 Abstract 81 A 2 Introduction 81 TABLE OF CONTENTS (Continued) Page A 3 Experimental procedures 84 A 3.1 Melanophores and chemical agents 84 A 3.2 Test chamber 84 A 3.3 Microscopy 85 A 3.4 Image digitization and analysis 85 A 4 Results 86 A 4.1 The nature of the melanophore response 86 A 4.2 Recognizing the complex shapes of active melanophores by digitizing their approach to a final simple shape 87 A 4.3 Motion detection by measuring incremental changes in pigmentation 89 A 5 Discussion 91 LIST OF FIGURES Figure Page 1.1 Diagram of a scale isolated from the fish Oreochromis niloticus 4 2.1 Diagrammatic representation of the buffer exchange system (BES) 14 2.2 Elevated potassium ion pretreatment of freshly isolated intact scales 20 2.3 Effects of guanethidine on a freshly isolated intact scale 23 2.4 Effects of capsaicin on freshly isolated intact scales 26 2.5 Response latency of norepinephrine on freshly isolated intact scales 32 2.6 Schematic diagram of pigment quivering in melanophore dendrites 37 2.7 Pulsation between neighboring melanophores on a scale 40 2.8 Hole formation of melanophores in freshly isolated intact scales 43 2.9 Reversal of holes by treatment with norepinephrine 45 3.1 Response of skinned scales to naphazoline 54 3.2 Response of norepinephrine clamped skinned scales to pheniramine 57 LIST OF APPENDIX FIGURES Figure Page 1. Chromatic changes in a single melanophore upon exposure to 1 p.M norepinephrine just prior to frame 1 99 2. Chromatic changes in a field of several melanophores upon successive exposure to 1 mM norepinephrine (frame 1), 0.1 mM dibutyryl cAMP (frame 5), and 100 mM yohimbine (frame 8) 100 LIST OF APPENDIX TABLES Table Page 1. Area, perimeter and circularity of features in processed images 97 2. Differential increases and decreases in pigmentation in a field of melanophores 98 BIOLOGICALLY INSPIRED BIOSENSORS FROM FISH CHROMATOPHORES 1. INTRODUCTION 1.1 Introduction The world is three-quarters water and within these waters there are thousands of species of aquatic animals with multiple shapes and colors. Species in the class Osteichthyes provide excellent examples of these unique shapes and colors. Of particular interest is the coloration of fish which has been shown to be important in their survival and communication. Many fish species are known to be capable of changing their coloration in response to a wide variety of environmental stimuli. There are several reasons why this action is of benefit to the individual, such as camouflage, intraspecies communication, mating, and competition. The ability of fish to change their color in response to environmental stimuli makes them a naturally occurring biosensor. Biosensors can be cells or arrays of cells that respond to a variety of stimuli in a way that can be easily monitored. The specific aims of this thesis are: (1) Examine the feasibility of using pigmented cells from fish as biosensors (2) Characterize the responses of chromatophores to a wide variety of compounds (3) Simplify the system of the biosensor. 2 1.2 Background 1.2.1 The system 1.2.1.1 Oreochromis niloticus as a model fish There are several reasons why Oreochromis niloticus or Nile tilapia, is a good choice of model system for this study. First, they are relatively easy to take care of and second, they have favorable physical attributes that make them a good choice for biosensor studies; large scales that can easily be isolated, numerous chromatophores on each scale, and each fish contains hundreds of scales. Nile tilapia are robust and will survive under many conditions. They also grow quickly, reaching a reasonable working size in only a few months. These are all desirable attributes that combine to create a fish that is easy to care for and demands little from the animal keeper in terms of time or money. In addition to the attributes above, the tilapia is a multicolored fish that is capable of undergoing color changes. The fish can change color from a very pale (almost white) to nearly black. These characteristics have led to their frequent use as research animals. 1.2.1.2 Structural characteristics of scales The anatomy of the scale is complex. The systematically layered structure of scales can be used to determine the age of fish. Scales are formed by successive layering of bio-mineralized matrix to yield extremely flattened 3 stacks, which, by age -10 months of the fish used in this study, are comprised of about 20 30 distinct layers. The view looking down on the scale, from a medial vantage point, reveals a focus surrounded by regular concentric and parallel circles termed circuli (Figure 1.1).
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