Use of Amino Acids in Fish Sperm Cryopreservation: A Review

Abstract

Sperm is protected against oxidative stress with seminal plasma. Dilution during cryopreservation is reduced the seminal plasma components having cells more sensitive to oxidative stress. Amino acids have antioxidant property and found in seminal plasma at high concentration. Therefore, amino acids have an important biological role for prevention of cell damage during cryopreservation. Thus far, conducted studies in mammalians have demonstrated that supplementation of amino acids (e.g. taurine, hypotaurine, proline, glutamine, glycine, histidin, and methionine) to extenders reduced sperm damage and DNA fragmentation and improved post-thaw motility. Recently, studies about antioxidant property and addition to extenders of amino acids have been performed in different fish species (Dicentrarchus labrax, Sparus aurata, Oncorhynchus mykiss, Salvelinus fontinalis, Pagrus major, Carassius auratus). In conducted studies, it has determined that addition of amino acids has reduced DNA fragmentation and protected DNA against strand breaks and also improved some sperm quality parameters post-thaw. In conclusion, amino acids provide better motility and lower DNA damage in fish sperm. However, studies on supplementation of amino acids to extenders in fish sperm cryopreservation are limited. Therefore, future studies in fish having economic and ecologic importance are necessary about effect of supplementation of amino acids in cryopreservation.

Keywords: Sperm; Cryopreservation; Amino acids

Introduction

The cryopreservation of fish sperm is an important technique due to transportation of genetic material among facilities, optimal utilization from aquaculture, reducing the risk of spreading infections, conducting of hybridization studies, biodiversity and gene pool conservation, selective breeding activities, and conservation of endangered species [1-4]. In addition, cryobanks could be provided to store in a genetically stable form of sperm and to maintain the biological functions of sperm cells for long terms [5,6]. On the other hand, even so there are numerous advantages of sperm cryopreservation, a lower physiological activity, structure deformation, DNA fragmentation, impairment of membrane stability and spermatozoa functionality, biochemical and metabolic changes, and a series of alterations could be occurred with cryopreservation process by oxidative stress due to generation of Reactive Oxygen Species (ROS) [7-9].

Sperm is protected against oxidative stress with seminal plasma. Dilution during cryopreservation reduces the seminal plasma components having cells more sensitive to oxidative stress [10]. Amino acids have antioxidant property and found in seminal plasma at high concentration. Therefore, amino acids have an important biological role for prevention of cell damage during cryopreservation. Thus far, conducted studies in mammalians have demonstrated that supplementation of amino acids (e.g. taurine, hypotaurine, proline, glutamine, glycine, histidine, and cysteine) to extenders reduced sperm damage and DNA fragmentation and improved post-thaw motility [11,12]. Recently, studies about benefit from antioxidant property and addition to extenders of amino acids have been performed in different fish species (Dicentrarchus labrax, Sparus aurata, Oncorhynchus mykiss, Salvelinus fontinalis, Pagrus major, Carassius auratus). [4,13-19]. This paper reviews the studies and results about addition of amino acids to extenders in cryopreservation process for fish sperm.

Amino Acids and Antioxidant Effects

Amino acids are the building blocks of peptides and proteins [20]. Particularly, sulfur-containing amino acids are important due to removing of free radicals and protection against oxidative stress. Because, sulphur a fundamental element for amino acids, proteins and other biomolecules. Methionine, cysteine, homocysteine, and taurine are the four common sulfur-containing [21].

Several amino acids (e.g. cysteine, glycine, proline and histidine) are found in seminal plasma. Lahnsteiner [22] stated that in the seminal plasma of O. mykiss, the main Free Amino Acids (FAAs) were arginine, glutamic acid, isoleucine, leucine, methionine and proline, in spermatozoa cysteine, arginine and methionine. The main FAAs in the seminal plasma of C. carpio were alanine, arginine, cysteine, glutamic acid, histidine, leucine, lysine, methionine and proline. To date, amino acids have been used in sperm cryopreservation as a nonpermeating cryoprotectant of many mammalian species to preventing against cold shock [23] and freezing stress [24-29]. Recently, studies about addition of amino acids to extenders have been performed in fish sperm cryopreservation.

Use of Amino Acids in Fish Sperm Cryopreservation

Motility, membrane stability and spermatozoa functionality, DNA integrity in fish sperm are affected by oxidative stress due to generation of Reactive Oxygen Species (ROS) during dilution in the extender media, cryoprotectant exposure and cooling process [7,8,10,30]. Especially, DNA integrity is one of indicators of cryopreservation success due to preserving genetic material and can be used in order to select the best treatment for fertilization trials [31]. DNA damage could be a result of free radical-induced damage because of ice crystal formation and recrystallisation during freezing-thawing procedure [17,32,33]. Studies about DNA damage after cryopreservation were performed in several species using the comet assay [34-37]. In some studies, it has been reported that cryopreservation process affected DNA stability by reason of DNA fragmentation [34-36]. Rani et al. [17] suggested that main reason of DNA damage is the toxicity of cryoprotectant. In contrast, Song and colleagues [38] stated that mechanical injury on sperm DNA stability was negligible. Suquet et al. [39] detected that there were not genome alterations in turbot Psetta maxima sperm after cryopreservation. Gwo et al. [40] determined that the nucleus of Atlantic croaker Micropogonias undulatus sperm was not affected from freeze-thaw process. Additionally, fertilization success depends on selecting the best treatment in cryopreservation process. Due to these reasons, usage of antioxidants in the cryopreservation is important for cryopreservation success. Antioxidants are useful for inhibition of ROS generation [41]. Recently, studies about addition to extenders of amino acids, which have antioxidant property, performed in different fish species (Table 1) [4,14-19,42].

  

    
Species 
    
Amino    acid 
    
Concentration    of amino acid (mM) 
    
Thawing    temperature (�C) 
    
Thawing    duration (s) 
    
Motility    (%) 
    
Researcher 
  
  

    
Sparus    aurata 
    
Taurine,    hypotaurine 
    
1, 10 
    
25 
    
30 
    
60-70 
    
Cabrita    et al. [10] 
  
  

    
Dicentrarchus    labrax 
    
Taurine,    hypotaurine 
    
1, 10 
    
25 
    
30 
    
60-70 
    
Cabrita    et al. [10], Martínez- Páramo et al. [42] 
  
  

    
Salvelinus    fontinalis 
    
Methionine 
    
1.5 
    
25 
    
30 
    
19-21 
    
Lahnsteiner    et al. [22] 
  
  

    
Oncorhynchus    mykiss 
    
Methionine 
    
1.5, 3 
    
25 
    
30 
    
17-21 
    
Lahnsteiner    et al. [22] 
  
  

    
Oncorhynchus    mykiss 
    
Taurine 
    
50, 75,    100 
    
35 
    
10 
    
48.8,    34.8, 4.2 
    
Ekici et    al. [16] 
  
  

    
Cyprinus    carpio 
    
L-cysteine 
    
0.5, 1,    1.5, 2 
    
82-92 
    
Kledmanee    et al. [46] 
  
  

    
Oncorhynchus    mykiss 
    
Methionine 
    
1,5 
    
40 
    
5 
    
69 
    
Kutluyer    et al. [4] 
  
  

    
Pagrus    major 
    
Taurine 
    
50, 100 
    
77-78 
    
Liu et    al. [15] 
  
  

    
Cyprinus    carpio 
    
Cysteine 
    
2.5, 5,    10, 20 
    
20 
    
30 
    
50-76 
    
Ogretmen    et al. [19] 
  
  

    
Carassius    auratus 
    
Methionine 
    
1, 1.5,    3, 6 
    
40 
    
5 
    
45 
    
Kutluyer    et al. [18] 
  

Table 1:  The amino acids used for cryopreservation of sperm in various fish species.