Effect of butylated hydroxytoluene (BHT) on the cryopreservation of common carp (Cyprinus carpio) spermatozoa

Supplementation of Extender with Melatonin Improves the Motility, Mitochondrial Membrane Potential, and Fertilization Ability of Cryopreserved Brown-Marbled Grouper Sperm

Sperm cryopreservation is a valuable tool for breeding, conservation, and genetic improvement in aquatic resources, while oxidative damage will cause a decline in sperm quality during this progress. Melatonin (MT), a natural antioxidant hormone, is used as an additive in sperm cryopreservation to reduce cellular damage from oxidative stress. Here, we aimed to investigate the effect of adding MT to the freezing medium in sperm cryopreservation of brown-marbled grouper (Epinephelus fuscoguttatus). Different concentrations of MT (0, 0.1, 0.25, and 0.5 mg/mL) were tested. We evaluated sperm motility, viability, apoptosis, mitochondrial membrane potential (MMP), and fertilization ability to assess the effects of MT supplementation. Our results demonstrated that the addition of MT to the extender improved the post-thaw motility, MMP, and fertilization ability of brown-marbled grouper sperm. The total motility, curvilinear velocity, straight linear velocity, and average path velocity in MT-treated groups (0.1 and 0.25 mg/mL) exhibited significantly higher values than that of the control group. A higher MMP (p < 0.05) was observed in the group treated with 0.25 mg/mL MT, suggesting that supplementation of MT in the extender might be able to protect mitochondrial membrane integrity effectively. Regarding fertilizing ability, 0.25 mg/mL MT yielded a significantly higher hatching rate than the control. An adverse effect was found with the concentration of MT up to 0.5 mg/mL, suggesting the possible toxicity of a high-dose addition. In this study, we optimized the sperm cryopreservation protocol of brown-marbled grouper, which might be valuable for sperm cryopreservation and sample commercialization of groupers and other fish.

Effect of type and concentration of antioxidant on sperm motility, viability, and DNA integrity of climbing perch Anabas testudineus Bloch, 1792 (Pisces: Anabantidae) post-cryopreservation

Sperm quality is preserved through the crucial involvement of antioxidants, which play a vital role in minimizing the occurrence of reactive oxygen species (ROS) during the cryopreservation process. The suitability of the type and concentration of antioxidants are species-dependent, and this study is crucial in order to improve the quality of the climbing perch sperm post-cryopreservation. Therefore, this study aimed to determine the best type and concentration of antioxidants for cryopreservation of climbing perch Anabas testudineus sperm. To achieve this, 6 types of antioxidants, namely, ascorbic acid, beta-carotene, glutathione, butylated hydroxytoluene (BHT), myo-inositol, and alpha-tocopherol, with inclusion of a control were tested in 3 replications at three concentration levels of 0 mg/L (control), 20 mg/L, 40 mg/L, and 60 mg/L. Sperm was diluted in a glucose-base extender at a ratio of 1:60 (sperm: glucose base), then 10 % DMSO and 5 % egg yolk was added before cryopreservation for two weeks. The results showed that the type and concentration of antioxidants had a significant effect on the motility and viability of cryopreserved climbing perch sperm (P < 0.05), where the best results for ascorbic acid, beta-carotene, glutathione, myo-inositol, and alpha-tocopherol were obtained at a concentration of 60 mg/L, while BHT was at a concentration of 20 mg/L. The best results for glutathione, myo-inositol, and alpha-tocopherol were significantly different from other treatments, while the best results for ascorbic acid and beta-carotene (60 mg/L) were not significantly different from the 40 mg/L concentration, while the best results for BHT were not significantly different from the control treatments. Therefore, the best concentration of glutathione, myo-inositol, and alpha-tocopherol was 60 mg/L, while for ascorbic acid and beta-carotene it was 40 mg/L, and BHT was not recommended. DNA integrity analysis indicated the absence of fragmentation in all samples, including fresh, control, and treated sperm. Based on practical and economic considerations, myo-inositol at 60 mg/L was recommended for cryopreservation of climbing perch A. testudineus sperm.

Use of cryoprotectors and antioxidants in sturgeon semen cryopreservation

In recent years, the possibility of increasing the low cryoresistance of sturgeon sperm by using antioxidants in basic cryoprotective media has been studied. The goal of this work was to review the current literature on impact of the cryoprotectors, well-known antioxidants and new multifunctional compounds on the activity indicators and fertilizing capability of sperm, as well as on biomarkers of cryostress. A special attention is given to the radical scavenging activity of studied compounds in relation to the highly reactive oxygen species, to prevent and negate oxidative stress damage of sturgeon sperm. Also, new trends for future research through the application of novel polyfunctional antioxidants to sturgeon sperm cryopreservation were indicated.

Improvement of Sperm Quality of the Depik Fish, Rasbora tawarensis, After Cryopreservation Using Antioxidant

BACKGROUND: The cryopreservation of the sperm of the depik fish, Rasbora tawarensis, has previously been developed. However, the quality of the sperm post cryopreservation was not satisfactory and might be improved through the application of antioxidants. OBJECTIVE: To determine the most suitable antioxidant for the cryopreservation of the depik fish spermatozoa. MATERIALS AND METHODS: A completely randomized design with a non-factorial experiment was used and the tested antioxidants were glutathione, β-carotene, ascorbic acid, and butylated hydroxytoluene (BHT) at 6% concentrations. All treatments had three replications. The sperms were collected from 10 male fishes and diluted with Ringer solution in a ratio of 1: 20 (v/v, sperm: Ringer solution). Then 5% DMSO and 5% egg yolk were added to the diluted sperms. Furthermore, 6% of the tested antioxidants were added to the diluents, and then, cryopreservation was carried out in liquid nitrogen for 14 days. RESULTS: The ANOVA test showed that the application of antioxidants significantly affected the sperm motility, fertility, and hatching rates of the eggs (P> 0.05). Furthermore, the antioxidants also protected the sperm cells during cryopreservation, with glutathione being the best antioxidant. CONCLUSION: The application of antioxidants during the cryopreservation of depik fish sperm had a significant effect on motility, fertility and hatchability of eggs post-cryo. Furthermore, glutathione was the most suitable antioxidant.

Antioxidants in Fish Sperm and the Potential Role of Melatonin

In recent years, the effects of novel antioxidants have played an important role in the research focusing on fish cell protection. As food demand grows, aquaculture production becomes more intensive, and fish are more exposed to oxidative stress conditions, like high densities, temperature shifting, frequent fish handling and samplings, and prophylactic or disease treatments, which expose fish to a different environment. Particularly in reproduction, germ cells lose antioxidant capacity with spermatogenesis, as spermatozoa are more prone to oxidative stress. Antioxidants have been used in a variety of fish physiological problems including in reproduction and in the establishment of cryopreservation protocols. From the most used antioxidants to natural plant food and herbs, and endogenously produced antioxidants, like melatonin, a review of the literature available in terms of their effects on the protection of fish spermatozoa is presented here in a classified structure. Several direct and indirect approaches to improve gamete quality using antioxidants administration are mentioned (through feed supplementation or by adding in cryopreservation media), as well as factors affecting the efficiency of these molecules and their mechanisms of action. Special attention is given to the unclear melatonin pathway and its potential scavenger activity to prevent and counteract oxidative stress damage on fish spermatozoa.

Does alpha-lipoic acid-loaded nanostructured lipid carriers improve post-thawed sperm quality and ameliorate apoptosis-related genes of rooster sperm?

Oxidative stress could be prevented by antioxidant-loaded nanoparticles. The purpose of this study was to assess the effects of 10 (A10), 20 (A20), 30 (A30), 40 (A40), and 50 (A50) μM alpha-lipoic acid and alpha-lipoic acid nanostructured lipid carriers (ALN) at 10 (ALN10), 20 (ALN20), 30 (ALN30), 40 (ALN40), and 50 (ALN50) μM on post-thawed sperm quality, fertility, and apoptosis-related genes of rooster sperm. The extender supplemented with ALN30 led to higher total and progressive motility, straight-line velocity, and linearity in comparison to the control group. The ALN30 resulted in higher percentage of mitochondria activity and glutathione peroxidase level compared with control (P < 0.05). The extender supplemented with ALN30 led to lower percentage of apoptotic sperm, when compared with the control. CASPASE 3 expression in ALN30 was lower (P < 0.05) than the other groups. The results showed that BCL-2 mRNA expression of sperm was significantly (P < 0.05) higher in ALN30 compared with the other groups (P < 0.05). Higher percentages of fertility and hatchability rates were observed in ALN30 group. The results indicate that ALN30 could be regarded as a novel potential cryoprotectant for the cryopreservation of rooster semen. Therefore, nanostructured lipid carriers improve not only the active compound (such as alpha-lipoic acid) of biomedical applicability but also the potential for industrial application in sperm cryopreservation.

Short-term storage sperm of coho salmon (Oncorhynchus kisutch) at 4 °C: Effect of sperm: Extender dilution ratios and antioxidant butyl-hydroxytoluene (BHT) on sperm function

Short-term storage of semen is a necessary key procedure in fish; it allows maximizing the use of gametes. Nevertheless, sperm quality decreases during storage has been associated with oxidative stress damage due to an increase in reactive oxygen species (ROS) during storage. This study was designed to optimize a short-term storage protocol for Coho salmon (Oncorhynchus kisutch) spermatozoa, evaluating the effect of extender dilution and the addition of butyl-hydroxytoluene (BHT) antioxidant on sperm function parameters. In the first experiment, fresh semen was diluted in Storfish®: extender dilution (1:2 and 1:3) and a control sample undiluted and stored at 4 °C for 7-days. In both experiments motility (MO), viability and integrity of plasma membrane, mitochondrial membrane potential (MMP) and superoxide anion level (O₂^-) were evaluated at 0, 3 and 7 days. Result shows that, 1:3 dilution maintained a higher sperm function for a longer period time. In the second experiment, spermatozoa were suspended in Storfish® (1:3) supplemented with two different concentrations of BHT (1.0 mM and 2.0 mM) and a control sample without antioxidant and stored at 4 °C for 7 days. The results demonstrated that, antioxidant-supplemented samples greater MO than control samples (P < 0.05). The viability remained >75% during storage in all groups. MMP was higher in 2.0 mM BHT compared to 1.0 mM and control (P < 0.05), in addition, this concentration reduced O₂^- level (P < 0.05). In conclusion, sperm: extender dilution 1:3 and adding of 2.0 mM BHT in sperm storage extender may enhance protection sperm function in Oncorhynchus kisutch against effects harmful of the oxidative stress during the in vitro storage.

Effect of alpha-lipoic acid on oxidative stress, viability and motility in the common carp (Cyprinus carpio) spermatozoa after short-term storage and cryopreservation

As known for different metabolic functions, α-lipoic acid (ALA) has been tested for spermatozoa preservation of animals as well as of human, but not for fish spermatozoa. The present study determined the effects of ALA on short and long-term (cryopreservation) preservation of common carp (Cyprinus carpio) spermatozoa, for the first time. For that, spermatozoa were diluted in extenders containing 0 (control), 0.025, 0.05, 0.1, 0.5, 1, 2, 5, and 10 mM of ALA concentrations in both short-term preservation and cryopreservation. Spermatozoa motility parameters by computer-assisted semen analysis, viability, lipid peroxidation and catalase activity in spermatozoa were conducted in both 2nd and 120th hours of short-term storage and post-thaw samples. Higher percentages of total spermatozoa motility (80 ± 3) and viability (87 ± 3) were observed in 0.5 mM ALA group after 120 h of incubation. In post-thaw samples, higher percentages of these parameters were in 1 mM ALA group (74 ± 3 and 83 ± 2, respectively). Moreover, the results have shown that the addition of ALA until concentrations of 2 mM improved especially spermatozoa curvilinear velocity, maintained viability, and suppressed excessive lipid peroxidation during the preservations. In conclusion, the additions of 0.5 mM ALA for short-term preservation and 1 mM ALA for cryopreservation were the optimal concentrations, and shown the protective effects on common carp spermatozoa, when considering all measured parameters together.

Positive effect of butylated hydroxytoluene (BHT) on the quality of cryopreserved cat spermatozoa

The semen cryopreservation processes are associated with state of oxidative stress induced by high levels of reactive oxygen species (ROS), causing damage to functional spermatozoa. Whereby, antioxidants have been utilized to scavenge or neutralize the elevated levels of ROS. The aim of at the present study was to evaluate the effect of adding BHT to the freezing extenders on post-thaw characteristics of domestic cat spermatozoa. Semen samples were frozen in Tris-fructose-citric acid-based extender, supplemented with different concentrations of BHT (0.5 mM, 1.0 mM and 2.0 mM) and a control sample without antioxidant. After thawing, sperm samples were assessed for motility by computer-assisted sperm analysis and viability, acrosome integrity, superoxide anion production and membrane lipid peroxidation status by flow cytometry. In the study, the parameters of sperm motility and acrosome integrity were significantly higher in 2.0 mM BHT compared to sperm frozen in the extender with other concentrations and control (P < 0.05), in addition, this concentration reduced significantly the superoxide anion production and lipid peroxidation of the sperm. The results demonstrated that the supplementation of BHT to the freezing extender could protect the function and cellular structure of domestic cat sperm from cryoinjuries.

ADIÇÃO DE HIDROXITOLUENO BUTILADO (BHT) NO DILUIDOR ACP-106c PARA CONGELAÇÃO DE SÊMEN CANINO

Resumo: Este estudo foi realizado para determinar o efeito de hidroxitolueno butilado (BHT) sobre a qualidade do sêmen canino congelado e descongelado, utilizando o diluidor à base de água de coco em pó (ACP-106c). Para tanto, foram realizadas quinze coletas de sêmen provenientes de cinco cães. O sêmen obtido foi diluído em ACP-106c acrescido de glicerol e gema de ovo. As amostras foram então transferidas para tubos contendo diferentes concentrações de BHT (0; 0,5; 1,0 e 2,0 mM). Em seguida, as amostras foram envasadas, congeladas e armazenadas em nitrogênio líquido. O sêmen coletado foi avaliado in natura quanto aos seguintes parâmetros: coloração, volume da fração espermática, motilidade total, vigor, concentração, morfologia e funcionalidade de membrana espermática. Após uma semana, as amostras foram descongeladas e avaliadas por meio de análise computadorizada, como também foram realizadas análises da funcionalidade de membrana e da morfologia espermática. A motilidade progressiva no grupo BHT 2,0 mM foi significativamente superior (P < 0,05) do que a do grupo BHT 0 mM (27,6 ± 11,7% vs. 19,0 ± 9,5%, respectivamente). Em todos os demais parâmetros avaliados, não houve diferença entre os grupos testados. Portanto, conclui-se que a adição do BHT ao diluidor ACP-106c não afetou a qualidade do sêmen canino pós-descongelação.

Studies of the cryopreservation condition of Gymnocypris przewalskii spermatozoa

The endemic naked carp (Gymnocypris przewalskii Kessler, 1876) plays an important role in the maintenance of the distinctive ecological system of Lake Qinghai at 3.2km altitude on the Qinghai-Tibet Plateau in China. This study aimed to develop a cryopreservation protocol for Gymnocypris przewalskii spermatozoa. Semen was collected from mature individuals during migration and frozen using the liquid nitrogen vapor method. The influence of different cryoprotectants and three extenders on the post-thaw quality of the sperm was analyzed. The highest sperm motility rate and longest motility time after cryopreservation were achieved by combining Ringer's solution with 15% ethylene glycol (P<0.05). The fertilization rate of this cryopreserved semen was 15.26±4.54%. This study thus provides a valuable method for the cryopreservation of the sperm of this important endangered fish species.

Cryobanking of aquatic species

This review is focused on the applications of genome cryobanking of aquatic species including freshwater and marine fish, as well as invertebrates. It also reviews the latest advances in cryobanking of model species, widely used by the scientific community worldwide, because of their applications in several fields. The state of the art of cryopreservation of different cellular types (sperm, oocytes, embryos, somatic cells and primordial germ cells or early spermatogonia) is discussed focusing on the advantages and disadvantages of each procedure according to different applications. A special review on the need of standardization of protocols has also been carried out. In summary, this comprehensive review provides information on the practical details of applications of genome cryobanking in a range of aquatic species worldwide, including the cryobanks established in Europe, USA, Brazil, Australia and New Zealand, the species and type of cells that constitute these banks and the utilization of the samples preserved.

STATEMENT OF RELEVANCE

This review compiles the last advances on germplasm cryobanking of freshwater and marine fish species and invertebrates, with high value for commercial aquaculture or conservation. It is reviewed the most promising cryopreservation protocols for different cell types, embryos and larvae that could be applied in programs for genetic improvement, broodstock management or conservation of stocks to guarantee culture production.

Effect of supplementation of butylated hydroxytoluene on post-thaw sperm viability, motility and membrane integrity of Hariana bulls

AIM

This study was aimed to see the beneficial effect of butylated hydroxytoluene (BHT) as a semen additive of Hariana bull semen.

MATERIALS AND METHODS

The study was carried out in Hariana bulls. Twenty-four ejaculates from two bulls were used for this study. Each ejaculate was extended with standard glycerolated egg yolk tris extender and supplemented with BHT at two concentrations as 0.5 mM (T1) and 1.0 mM (T2). After dilution, equilibration and 24 h of cryopreservation, the samples were analyzed for progressive motility, sperm viability and membrane integrity.

RESULTS

Progressive motility, sperm viability and sperm membrane integrity were significantly (p<0.05) increased in the samples fortified with BHT as compared to the control during the process of cryopreservation and thawing. The BHT concentration of 1 mM revealed better results as compared to 0.5 mM.

CONCLUSION

Addition of 1.0 mM BHT was found better in cryopreservation of Hariana bull semen compared to 0.5 mM BHT and control samples. The addition of BHT has improved the sperm quality by acting as an antioxidant thereby reducing the lipid peroxidation of the sperms.