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RELATIONSHIP BETWEEN SPERM MOTILIY AND FERTILIZATION RATES the first time, the relationship between all the parameters provided by a CASA system and the fertilization and hatching rates in a marine fish species. Total motility (TM) and progressive motility (PM) are recognized as important sperm traits for male fertility and sperm competition in fish (Rurangwa et al., 2004). In the present study, high correlations were found between these parameters and FR and HR (r ~ 0.7), the same as occurs in some fish species such as Atlantic halibut (Hippoglossus hippoglossus; (Ottesen et al., 2009)), red seabream (Pagrus major, (Liu et al., 2007)) or common carp (Cyprinus carpio, (Linhart et al., 2000)). However, parallel studies about this relationship in other species have given conflicting results, as negligible correlations were found between TM or PM and fertilization potential (Bozkurt and Secer, 2006). In this respect, it is worth highlighting that fertilization trials should be carried out both with an optimal sperm/egg ratio and using a wide range of sperm motility values in order not to mask the real correlations between the motility values and the fertilization and hatching rates (Moccia and Munkittrick, 1987). On the other hand, in addition to the percentage of motile spermatozoa as a good tool to predict fertilization ability, spermatozoa velocities may also serve as prognostic indicators of the fertilization potential of sperm (Liljedal et al., 2008). In fact, in our study the highest coefficients of correlation and determination were found for VCL, VSL and VAP, which showed better correlations with FR and HR than the parameters traditionally used to define sperm quality (TM and PM). This result can be explained through logical hypothesis: at the gamete level, the egg-sperm contact could be influenced by several factors such as the amount of spermatozoa, the number of motile spermatozoa, sperm velocity and sperm longevity. When in IVF trials the number of spermatozoa becomes a limiting factor (tight sperm/egg ratio), increases in spermatozoa velocities will enable spermatozoa to look for the egg and penetrate the micropyle at a faster rate per time unit, increasing in this way fertilization success (Gage et al., 2004 and Linhart et al., 2005). In this respect, the results obtained in Trial 1 using 10 3 and 10 4 sperm/egg ratios support this hypothesis, and sharp decreases in fertilization rates were found when the sperm used showed significantly lower velocities but similar motilities (Fig 3). 119
CHAPTER 5 Similar data has been reported in other marine species such as Atlantic salmon (Salmo salar), Atlantic cod (Gadus morhua) or green swordtail (Xiphophorus helleri), in which spermatozoa velocity seems to be the major component that determines fertilization success and the proportion of the paternity through the sperm competition (Gage et al., 2004, Gasparini et al., 2010 and Rudolfsen et al., 2008). In this respect, new approaches in relation to male´s broodstock selection through sperm kinetics features can be used from this perspective. Improvements in the aquaculture sector could optimize the reproductive efficiency in the fish farms, making rational use of gametes possible, limiting the number of breeding fish and, thus, reducing production costs. However, it is important to highlight that breeding fish programs involves a lot of factors and, reducing the number of breeders we could also be decreasing the genetic diversity/basis of broodstock. Therefore, the proper application of several factors among these programs will define the further improvements in aquaculture sector. Finally, it is important to highlight that besides the sperm/egg ratio and sperm kinetic parameters other factors involved in IVF can modulate fertilization and hatching rates. For example, variations in the spawning environment, oocyte quality, oocyte size or even the micropyle closing time can determine the final results. Therefore, it appears that it is critical to maintain identical fertilization conditions when sperm doses for IVF trials must be estimated, with the aim of avoiding masking effects through the experimental variables (Chereguini et al., 1999). To sum up, this study showed that both sperm/egg ratios and some sperm kinetic parameters provided by CASA system play a crucial role in the fertilization and hatching success in pufferfish. These kinetic parameters have been defined throughout the IVF trials, and linear regression equations have been developed to the most important parameters with the aim of determining proper values of fertilization and hatching rates. In this respect, spermatozoa velocity seems to be a key factor in this event, especially when the number of spermatozoa per egg is limited in the aqueous environment. This kind of study can serve as a basis for improved efficiency in broodstock management fish reproduction. 120
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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,
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CHAPTER 2 Spermiating males (%) 100
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CHAPTER 2 100 80 60 I II III IV A 4
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CHAPTER 2 3.2 Hormonal treatments P
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CHAPTER 2 With regard to the sperm
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CHAPTER 2 Relative volume (%) 80 I
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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 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
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
Page 166 and 167: REFERENCES Rurangwa E, Volckaert FA
Page 168 and 169: REFERENCES Tesch F. Telemetric obse
Page 170 and 171: REFERENCES Wong PYD, Lee WM, Tsang
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