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RELATIONSHIP BETWEEN SPERM MOTILIY AND FERTILIZATION RATES Abstract The use of high quality gametes from both males and females during in vitro fertilization (IVF) trials is an essential step in order to achieve high fertilization and hatching rates. Although aquaculture hatcheries have focused more on egg rather than spermatozoa quality, some studies have demonstrated that sperm quantity and quality have a great influence both on fertilization/hatching success. In this study we have demonstrated that sperm/egg ratio and sperm quality are factors strongly related to each other in the pufferfish (Takifugu niphobles). Our results suggest that both factors should be taken into account as unique interrelated elements, making possible to obtain high fertilization rates using a successful combination of small amount of high quality sperm or high amount of low quality sperm. In addition, coefficients of correlation and determination among all the sperm motion parameters provided by a CASA system and fertilization/hatching rates were estimated for the first time in a marine species. Positive significant correlations were found in some parameters such as total and progressive motility (0.68 and 0.70 respectively). However, curvilinear velocity (VCL), straight line velocity (VSL) and average velocity (VAP) showed the highest coefficients of correlation (0.82, 0.80, and 0.81, respectively). In this respect, spermatozoa velocity appears to be a key factor in the fertilization process, especially when the number of spermatozoa per egg is limited in the aqueous environment. 1. Introduction The pufferfish (Takifugu niphobles) is a teleost fish with a wide distribution in the Northwest Pacific Ocean. This species is one of around 24 pufferfish species in the tetraodontine genus Takifugu, and it presents own interesting features to preserve it: 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 107
CHAPTER 5 Takifugu rubripes, is widely-kept by scientists as a model organism (Aparicio et al., 2002) so Takifugu niphobles could be used like this due to its small and similar genome (Brenner et al., 1993). Breeding in captivity of Takifugu spp. involves the handling of captive fish broodstocks and the collection of gametes both from males and females for the application of in vitro fertilization (IVF). This technique is essential for the reproductive manipulation of some fish species such as T. niphobles, which displays an exclusive and complex spawning behavior because spawning does not happen spontaneously under cultured conditions. The general hatchery protocol for IVF in fish involves mixing quiescent spermatozoa with a batch of oocytes, followed by activation through the addition of seawater and finally, the incubation of the fertilized eggs in order to promote embryo development and hatching (Yasui et al., 2012). The use of high quality gametes both from males and females during this process is essential in order to achieve both suitable fertilization and hatching rates. In this respect, despite the fact that aquaculture hatcheries have focused more on egg rather than sperm quality (Snook, 2005), some studies have demonstrated that spermatozoa quality has a great influence both on fertilization success and the subsequent development of the embryo and larvae (Butts et al., 2011 and Ottesen and Babiak, 2007). From a practical viewpoint, the sperm quality can be measured by any quantifiable parameter which is directly correlated related to fertilization capacity. Spermatozoa motility has been the most commonly used parameter in evaluating sperm quality (Kime et al., 2001), but other features such as sperm density, plasma composition, head morphology or ATP concentration can be also useful tools to measure sperm quality (Fauvel et al., 2010). The gradual appearance of the computer assisted sperm analysis (CASA) has allowed an objective, rapid and accurate assessment of fish sperm samples, including T. niphobles (Gallego et al., Chapter 4). This kind of software is able to provide a high number of parameters, which can be related to fertilization ability and thus, to sperm quality. However, despite the fact that there are some studies about the relationship between the percentage of motile cells and fertilization and 108
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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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CHAPTER 2 Study of the effects of t
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CHAPTER 2 reducing the pressure on
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CHAPTER 2 ongoing task in order to
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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 95 and 96: CHAPTER 4 2002) so Takifugu niphobl
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 118 and 119: 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
Page 145 and 146: CONCLUSIONS vii. The coefficients o
Page 148 and 149: REFERENCES Aarestrup K, Økland F,
Page 150 and 151: REFERENCES Beirão J, Cabrita E, P
Page 152 and 153: REFERENCES Cabrita E, Robles V, Cu
Page 154 and 155: REFERENCES De Vos A, Van De Velde H
Page 156 and 157: REFERENCES Gallego V, Pérez L, Ast
Page 158 and 159: REFERENCES sperm competition and fe
Page 160 and 161: REFERENCES Liu QH, Li J, Xiao ZZ, D
Page 162 and 163: REFERENCES Mortimer ST. Effect of i
Page 164 and 165: 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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