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GENERAL INTRODUCTION spermatozoa kinetic parameters were negatively affected by the depletion of this ion. Thus, it seems clear that there is a wide interspecific variability in relation to the presence/absence of extracellular ions and the effect thereof on the sperm motion parameters, so more studies focusing on this topic are necessary in order to design optimum species-specific activation media. On the other hand, scarce studies regarding the intracellular ion changes after sperm activation of marine fish have been published (Oda and Morisawa, 1993; Takai and Morisawa, 1995). Nowadays, the widely accepted model in marine species suggests that a hyperosmotic shock causes a spermatozoa membrane depolarization, which in turn results in an increase in Ca 2+ and K + inside the cell, which is the key factor triggering sperm motility (Figure 4). Quiescent sperm in seminal plasma pH increase Hypothesis? Initiation of sperm motitlity Hyperosmotic shock K + increase Hypothesis? ATP stores decreases Membrane depolarization Ca 2+ increase Hypothesis? Motility stops Figure 4. Activation process and signal transduction in marine spermatozoa: scheme of the interacting processes occurring during the motility period. However, neither the origin 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 investigated. In this respect, new studies involving detailed protocols, channel blockers, etc. must be carried out in order to find out the specific mechanisms which occur during motility activation in marine fish sperm. 15
GENERAL INTRODUCTION 3. Sperm quality in fish From an aquacultural point of view, breeding in captivity of some marine species is a key factor in reaching reproductive success, and the main limitations are the quantity and quality of male and female gametes. However, until recently gamete quality has not received much attention, and only a few studies have been published about the effect of specific factors on gamete quality (see review Bobe and Labbé, 2000). Traditionally, hatcheries have focused more on the quality of eggs and larvae rather than that of sperm, even though sperm quality also affects the performance of larvae production (Trippel and Nielson, 1992). In fact, sperm in commercial hatcheries is often inadequate both in terms of quantity and quality and often optimal fertilisation rates are not reached through in vitro fertilization trials (Rurangwa et al., 2004). Therefore, it appears that the assessment of sperm quality would be a useful tool that could be applied in a wide range of reproduction fields, and several factors such as artificial fertilization, chilled storage, cryopreservation or even the effect of environmental pollutants on fish reproductive success could be improved by sperm quality evaluation (Cabrita et al., 2005a; Fabroccini et al., 2010). First of all, it seems essential to define and understand what sperm quality means. From a biological standpoint, sperm quality could be defined as the ability ofthe spermatozoa to reach and fertilize the oocyte (Fauvel et al., 2010). In this respect, any quantifiable parameter directly correlated with the fertilization capacity could potentially be used as a sperm quality indicator. Sperm is the final result of a maturation process in which several haploid cells are produced with the aim of transmitting paternal genetic information to the next generation. It is important to highlight that throughout this process, several factors can affect the sperm quality and thus, fertilization success. The most important factors are displayed in Table 1, all of different origins, from the reproductive age of the breeder to the hormonal treatment (if required) applied to achieve artificial maturation. Therefore, in order to achieve good quality sperm it is essential to take all these factors into account, because slight variations in any of them could negatively affect the sperm quality and thus, decrease fertilization success. 16
Page 2 and 3: SPERM PHYSIOLOGY AND QUALITY IN TWO
Page 4 and 5: ACKNOWLEDGEMENTS Muchos años han p
Page 6 and 7: aunque tiene una alcachofa en la ca
Page 8 and 9: TABLE OF CONTENTS SUMMARY 1 RESUMEN
Page 10 and 11: SUMMARY SUMMARY The conservation st
Page 12 and 13: RESUMEN RESUMEN Las especies objeto
Page 14 and 15: RESUM RESUM Les espècies objecte d
Page 16: GENERAL INTRODUCTION 7
Page 19 and 20: GENERAL INTRODUCTION who postulated
Page 21 and 22: GENERAL INTRODUCTION 2. Sperm physi
Page 23: GENERAL INTRODUCTION Finally, the a
Page 27 and 28: GENERAL INTRODUCTION in fish (Kime
Page 29 and 30: GENERAL INTRODUCTION However, for s
Page 31 and 32: GENERAL INTRODUCTION future applica
Page 33 and 34: GENERAL INTRODUCTION With regards t
Page 36: OBJECTIVES The chapters presented b
Page 40 and 41: STANDARDIZATION OF SPERM MOTILITY E
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
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CHAPTER 2 In this respect, it is we
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CHAPTER 2 treatment to that of the
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CHAPTER 2 Our results demonstrate t
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ROLE OF IONS IN THE SPERM ACTIVATIO
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CHAPTER 4 Study of pufferfish (Taki
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CHAPTER 4 2002) so Takifugu niphobl
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CHAPTER 4 carrying out sperm collec
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CHAPTER 4 Table 1. Activation media
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CHAPTER 4 TM (%) 100 A a a Und-PD a
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CHAPTER 4 TM (%) 80 60 40 20 0 A a
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CHAPTER 4 TM (%) 80 A ASW100 GLU 60
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CHAPTER 4 although the activation m
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CHAPTER 4 dilution ratio and an opt
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CHAPTER 4 2006). Several studies in
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CHAPTER 4 5. Conclusions Some concl
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RELATIONSHIP BETWEEN SPERM MOTILIY
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GENERAL DISCUSSION 1. Improvements
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GENERAL DISCUSSION profiles induced
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GENERAL DISCUSSION more studies on
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GENERAL DISCUSSION sperm motility p
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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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