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IN-DEPTH STUDY OF SPERM ACTIVATION IN PUFFERFISH Abstract The first goal of this study was the development of a short-term storage method for pufferfish (Takifugu niphobles) sperm. In this respect, the best results were obtained by diluting the sperm in a seminal-like solution and keeping it in a Petri dish in chilled storage (4 ºC). This method was successful in preserving sperm quality parameters without resulting in differences in fresh sperm for a relatively long-term period (7 days), for use in aquaculture matters. The addition of bovine serum albumin (BSA) to the medium did not improve the results. On the other hand, both the osmolality and the ion composition of the media are essential factors which can modulate the sperm motility parameters. The osmolality of the activating medium was the most important factor in triggering pufferfish sperm motility, and osmolalities of 750-825 mOsm/kg were necessary to initiate this process, demonstrating that it appears to be a dose-independent mechanism. Regarding the ion composition of the activation media, this study has shown that despite the spermatozoa being able to initiate movement without any ion in the activation medium, the absence of ions can negatively affect the kinetic parameters of the spermatozoa. Finally, in natural conditions (seawater), the activation of sperm motility generates intracellular increases in Ca 2+ and K + , suggesting that these ions play an essential role in the activation mechanism of pufferfish sperm. 1. Introduction The pufferfish (Takifugu niphobles) is a teleost fish with a wide distribution in the Northwest Pacific Ocean, most commonly around Japan, Taiwan and Vietnam. This species is one of around 24 pufferfish species in the tetraodontine genus Takifugu, and it displays interesting features for its own preservation: i ) it is placed on the IUCN Red List due to the fact that its current population is not well known, making it a possible endangered species (Roberts, 1996); and ii) another closed species, like Takifugu rubripes, is widely-kept by scientists as a model organism (Aparicio et al., 85
CHAPTER 4 2002) so Takifugu niphobles could be used like this due to its small and similar genome (Brenner et al., 1993). Reproduction of Takifugu spp. involves the collection/handling of sperm samples, and often it is necessary to store this sperm during a relatively long period, from a few hours to several days. Different media for the cold storage (4 ºC) of fish sperm have been developed to improve the sperm handling of several freshwater and seawater teleosts, including rainbow trout, Oncorhynchus mykiss (Billard, 1981), zebra fish, Danio rerio (Jing et al., 2009), sturgeon, Acipenser oxyrinchus desotoi (Park and Chapman, 2005), striped bass, Morone saxatilis (Jenkins-Keeran and Woods, 2002), walking catfish, Clarias macrocephalus (Vuthiphandchai et al., 2009) and the European eel, Anguilla anguilla (Peñaranda et al., 2010c,d). In terms of the pufferfish sperm, a seminal-like solution has usually been used as the standard dilution agent (Krasznai et al., 2003). Despite the fact that this diluent has only ever been used on the day of sperm collection, its preservation capability over a longer period (a few days) has never been checked. Therefore, the main aim of this study was to develop a simple method for cold storage able to preserve the sperm quality parameters of Takifugu niphobles spermatozoa over a short-term period. On the other hand, it is well known that spermatozoa of teleost species are immotile in the male reproductive organ, or in electrolyte or nonelectrolyte solutions with a similar osmolality to that of the seminal plasma (Alavi and Cosson, 2006). In marine teleosts, such as pufferfish, the increase in environmental osmolality is the main factor determining the activation of sperm motility (Cosson, 2004; Morisawa, 2008; Takai and Morisawa, 1995). The osmotic shock faced by the spermatozoa when they are released into the marine environment leads to a rapid influx/efflux of ions/water between intracellular and extracellular spaces. In this respect, the increase in intracellular concentrations of Ca 2+ and K + ions has been proposed as the trigger for the initiation of sperm motility in marine fishes (Morisawa, 2008). However, neither the origin/nature of these ions (from the extracellular medium or intracellular stores) nor their specific effects on motility and the kinetic parameters measured by CASA systems have been described. 86
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SPERM PHYSIOLOGY AND QUALITY IN TWO
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ACKNOWLEDGEMENTS Muchos años han p
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aunque tiene una alcachofa en la ca
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TABLE OF CONTENTS SUMMARY 1 RESUMEN
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SUMMARY SUMMARY The conservation st
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RESUMEN RESUMEN Las especies objeto
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RESUM RESUM Les espècies objecte d
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GENERAL INTRODUCTION 7
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GENERAL INTRODUCTION who postulated
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GENERAL INTRODUCTION 2. Sperm physi
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GENERAL INTRODUCTION Finally, the a
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GENERAL INTRODUCTION 3. Sperm quali
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GENERAL INTRODUCTION in fish (Kime
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GENERAL INTRODUCTION However, for s
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GENERAL INTRODUCTION future applica
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GENERAL INTRODUCTION With regards t
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OBJECTIVES The chapters presented b
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STANDARDIZATION OF SPERM MOTILITY E
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Page 56: CHAPTER 2 Study of the effects of t
Page 59 and 60: CHAPTER 2 reducing the pressure on
Page 61 and 62: CHAPTER 2 ongoing task in order to
Page 63 and 64: CHAPTER 2 To measure sperm density,
Page 65 and 66: CHAPTER 2 Spermiating males (%) 100
Page 67 and 68: CHAPTER 2 100 80 60 I II III IV A 4
Page 69 and 70: CHAPTER 2 3.2 Hormonal treatments P
Page 71 and 72: CHAPTER 2 With regard to the sperm
Page 73 and 74: CHAPTER 2 Relative volume (%) 80 I
Page 75 and 76: CHAPTER 2 In this respect, it is we
Page 77 and 78: CHAPTER 2 treatment to that of the
Page 79 and 80: CHAPTER 2 Our results demonstrate t
Page 82 and 83: ROLE OF IONS IN THE SPERM ACTIVATIO
Page 92: CHAPTER 4 Study of pufferfish (Taki
Page 97 and 98: CHAPTER 4 carrying out sperm collec
Page 99 and 100: CHAPTER 4 Table 1. Activation media
Page 101 and 102: CHAPTER 4 TM (%) 100 A a a Und-PD a
Page 103 and 104: CHAPTER 4 TM (%) 80 60 40 20 0 A a
Page 105 and 106: CHAPTER 4 TM (%) 80 A ASW100 GLU 60
Page 107 and 108: CHAPTER 4 although the activation m
Page 109 and 110: CHAPTER 4 dilution ratio and an opt
Page 111 and 112: CHAPTER 4 2006). Several studies in
Page 113 and 114: CHAPTER 4 5. Conclusions Some concl
Page 116 and 117: RELATIONSHIP BETWEEN SPERM MOTILIY
Page 130: RELATIONSHIP BETWEEN SPERM MOTILIY
Page 134 and 135: GENERAL DISCUSSION 1. Improvements
Page 136 and 137: GENERAL DISCUSSION profiles induced
Page 138 and 139: GENERAL DISCUSSION more studies on
Page 140 and 141: GENERAL DISCUSSION sperm motility p
Page 142: CONCLUSIONS 133
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CONCLUSIONS vii. The coefficients o
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REFERENCES Aarestrup K, Økland F,
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REFERENCES Beirão J, Cabrita E, P
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REFERENCES Cabrita E, Robles V, Cu
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REFERENCES De Vos A, Van De Velde H
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REFERENCES Gallego V, Pérez L, Ast
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REFERENCES sperm competition and fe
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REFERENCES Liu QH, Li J, Xiao ZZ, D
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REFERENCES Mortimer ST. Effect of i
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REFERENCES Peñaranda DS, Marco-Jim
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REFERENCES Rurangwa E, Volckaert FA
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REFERENCES Tesch F. Telemetric obse
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REFERENCES Wong PYD, Lee WM, Tsang
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