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RELATIONSHIP BETWEEN SPERM MOTILIY AND FERTILIZATION RATES Finally, fertilization and hatching rates showed a high and significant correlation between them (Fig. 5). Hatching rate (%) 100 80 60 40 20 0 r = 0.99 y = 1.01x - 2.95 0 20 40 60 80 100 Fertilization rate (%) Figure 5. Relationship between fertilization and hatching rates (n=15; the experimental unit is each Petri Dish). Data from Trial 2 was used to determine the correlations and linear regression equation was calculated. 4. Discussion Sperm/egg ratio and sperm quality are the main factors affecting fertilization and hatching success in artificial insemination trials (Linhart et al., 2008 and Trippel and Neilson, 1992). During the present study, the unavailability of low quality fresh sperm samples forced us to work with spermatozoa at different post-activation times with the aim of mimicking sperm samples of different qualities. Thus, during this study the sperm activated after 5 s represent the high-quality sperm samples (high motility and velocity values) while the sperm activated after 20 (high motility and intermediate velocity values) and 40 s (low motility and velocity values) resemble the medium and low quality sperm samples, respectively. However, it must be noted that the swimming time/speed of sperm activated after 20 and 40 s may be shorter than medium and low quality fresh samples. In this study we have demonstrated that sperm/egg ratio and sperm quality are factors which are strongly related to each other: when high-quality 117
CHAPTER 5 sperm samples (sperm activated after 5 s) were used in the IVF trials, all the different sperm/egg ratios tested produced high fertilization rates (> 80%). However, when lower quality sperm samples (sperm activated after 20 or 40 s) were used, the amount of sperm became an essential element in reaching suitable fertilization rates. These results suggest that both sperm/egg ratio and sperm quality should be taken into account as unique interrelated factors, with it possible to obtain high fertilization rates using a successful combination of high/low quality sperm in high/low volumes. Nowadays, the aquaculture sector is going through a delicate situation and improvements in some issues with regards to IVF should be carried out (Gallego et al., Chapter 2). In this respect, fixing an appropriate combination of the number of spermatozoa per oocyte seems to be a useful tool to optimize the reproductive efficiency in fish farms. However, little data has been reported in marine species about the optimum sperm/egg ratio, which seems to be a species-specific parameter, finding ratios from 10 3 in Atlantic croacker (Micropogonias undulatus, (Gwo et al., 1991)) to 10 6 in northern pike (Esox lucius, (Zhang et al., 2011)). In this study, we have demonstrated that sperm/egg ratios from 10 3 to 10 5 can be used to achieve proper fertilization rates in pufferfish. However, the optimal sperm/egg ratio depends on the sperm sample quality, so, when good sperm samples are available, it would be possible to use low sperm/egg ratios (≤ 10 3 ); while when sperm samples with high motilities and velocities values are not available, it would be necessary to use higher sperm/egg ratios (≥ 10 5 ) to achieve high fertilization rates in this species. On the other hand, the use of high quality gametes both from males and females is the other essential factor to reach suitable fertilization and hatching rates both for aquaculture and scientific purposes. With regards to male´s gametes, the percentage of motile cells has been the most used parameter to estimate sperm quality. However, for many years the conventional method of motility evaluation has been subjective, and the current appearance of CASA systems has made it possible to estimate a higher number of sperm parameters by an objective, rapid and accurate technique (Gallego et al., Chapter 1). In this study we have estimated, for 118
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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
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 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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