Background: Using cryovial for freezing dog spermatozoa provides a practical method to increase extended sperm volume and shorten the time required for equilibration by using a simple freezing techniques. The purpose of this study was to determine the optimal thawing condition for dog sperm cryopreservation using cryovials. Methods: For sperm freezing, cryovials with 200 × 106 sperm/mL were cooled after the addition of tris egg yolk extender (TEY) at 4℃ for 20 min, then TEY with 4% glycerol was added and equilibrated for another 20 min before being aligned over LN2 vapor for another 20 min and plunged directly into LN2. Spermatozoa were thawed in a water bath at 37℃ for varying times (25 sec, 60 sec, 90 sec, and 120 sec) in the first experiment. In the second experiment, spermatozoa were thawed in a water bath at various temperatures and times (37℃ for 1 min, 37℃ for 1 min with gentle stirring, 24℃ for 24 min, and 75℃ for 20 sec). In these experiments, the effect of thawing conditions on motility parameters, viability (SYBR-14/PI), and acrosome integrity (PSA/ FITC) of spermatozoa were investigated. Results: The post-thaw sperm motility parameters, viability, and acrosome integrity were not significantly different across the experimental groups. Conclusions: In this study, the characteristics of spermatozoa frozen using cryovials were not significantly affected by various thawing conditions.

In 1951, Colin Russell Austin and Min Chueh Chang identified “capacitation”, a special process involving ejaculated spermatozoa in the female reproductive tract. Capacitation is a phenomenon that occurs in vivo , but almost all knowledge of capacitation has been obtained from in vitro studies. Therefore, numerous trials have been performed to establish in vitro capacitation methods for various studies on reproduction. Although a series of studies have been conducted to develop an optimal protocol for inducing capacitation, most have focused on identifying the appropriate chemical compounds to induce the capacitation of boar spermatozoa in vitro. Therefore, the purpose of this study was to identify the optimal incubation time for inducing capacitation in vitro. Duroc semen was incubated for various periods (60, 90, and 120 min) to induce capacitation. Sperm function (sperm motility, motion kinematic parameters, and capacitation status) was evaluated. The results showed that total sperm motility, rapid sperm motility, progressive sperm motility, curvilinear velocity, and average path velocity significantly decreased in a time-dependent manner. However, the capacitation status did not show any significant changes. Taken together, these results indicate that an incubation time of more than 60 min suppresses sperm motility and motion kinematic parameters. Therefore, we suggest that 60 min may be the best incubation time to induce capacitation without negative effects on sperm motility and motion kinematics in boar spermatozoa in vitro.

Epididymal sperm cryopreservation provides a potential method for preserving genetic material from males of endangered species. This pilot study was conducted to develop a freezing method for tiger epididymal sperm. We evaluated post-thaw sperm condition using testes with intact epididymides obtained from a Siberian tiger (Panthera tigris altaica ) after castration. The epididymis was chopped in Tyrode's albumin-lactate-pyruvate 1x and incubated at 5% CO2, 95% air for 10 min. The Percoll separation density gradient method was used for selective recovery of motile spermatozoa after sperm collection using a cell strainer. The spermatozoa were diluted with modified Norwegian extender supplemented with 20 mM trehalose (extender 1) and subsequent extender 2 (extender 1 with 10% glycerol) and frozen using LN2 vapor. After thawing at 37℃ for 25 s, Isolate® solution was used for more effective recovery of live sperm. Sperm motility (computerized assisted sperm analysis, CASA), viability (SYBR-14 and Propidium Iodide) and acrosome integrity (Pisum sativum agglutinin with FITC) were evaluated. The motility of tiger epididymal spermatozoa was 40.1 ± 2.0%, and progressively motile sperm comprised 32.7 ± 2.3%. Viability was 56.3 ± 1.6% and acrosome integrity was 62.3 ± 4.4%. Cryopreservation of tiger epididymal sperm using a modified Norwegian extender and density gradient method could be effective to obtain functional spermatozoa for future assisted reproductive practices in endangered species.

The objective of this study was to establish a selection process for high quality sperm in bovine semen using sperm separation by magnetic activation (MACS). For this, semen from 21 Nellore bulls was collected using an artificial vagina. To guarantee the presence of pathologies in the ejaculate, animals previously declassified in four consecutive spermiogram were used. Semen was analyzed in five statuses: (1) fresh semen (fresh); (2) density gradient centrifugation (DGC), percoll column; (3) non-apoptotic fraction after separation by MACS (MAC); (4) apoptotic fraction from the separation (MACPOOR); and (5) MAC followed by DGC (MACDGC). Using a computerized analysis system (CASA), motility was measured. The sperm morphology was evaluated by phase contrast, and the supravital test was completed with eosin/nigrosin staining. For DGC, 20 × 106 cells were used in a gradient of 90% and 45% percoll. MACS used 10 × 106 cells with 20 μL of nanoparticles attached to annexin V, and filtered through the MiniMACS magnetic separation column. Membrane integrity was assessed with SYBR-14/IP and mitochondrial potential with JC-1 by flow cytometry. Processing sperm by MACDGC, was more effective in obtaining samples with high quality sperm, verified by the total of abnormalities in the samples: 35.04 ± 2.29%, 21.50 ± 1.47%, 17.30 ± 1.10%, 30.68 ± 1.94% and 10.50 ± 1.46%, respectively for fresh, DGC, MAC, MACPOOR, and MACDGC. The subpopulation of non-apoptotic sperm had a high number of live cells (82.65%), membrane integrity (56.60%) and mitochondrial potential (83.98%) (p < 0.05). These findings suggest that this nanotechnological method, that uses nanoparticles, is efficient in the production of high-quality semen samples for assisted reproduction procedures in cattle.

In the present study, we examined if deep uterine artificial insemination (DUAI) can improve the pregnancy rate of artificial insemination (AI) using epididymal spermatozoa (ES) in Hanwoo cattle. The estrus cycles of 88 Hanwoo cows were synchronized, and 17 cows were artificially inseminated using the DUAI method with ES, 20 cows were artificially inseminated via the uterine body (BUAI) method with ES, and as a control, 51 cows were inseminated by using the BUAI method with ejaculated spermatozoa from 1 proven bull after frozen thawing. The pregnancy rate of the DUAI method (58.8%) was higher than that of the BUAI method (25.0%, p = 0.0498). The motility of ES was examined immediately after thawing and after 3 and 6 h of incubation. The rapid progressive sperm motility of the control group was significantly higher than that of the ES group immediately after thawing and after 3 and 6 h of incubation (p < 0.05). The straight line velocity and average path velocity of the ES group after 6 h of incubation were significantly lower than those in the control group (p < 0.05). The linearity and amplitude of lateral head of ES were lower than those at 6 h (p < 0.05). The flagellar beat cross frequency and hyperactivation of ES were lower than the control spermatozoa immediately after thawing and at 3 h (p < 0.05). These motility parameters suggested that ES had a low motility and fertilization ability compared to the control spermatozoa. After frozen-thawing and 3 h of incubation, the percentage of live spermatozoa with intact acrosomes in the ES was significantly lower than that in ejaculated spermatozoa (p < 0.05). Our findings suggested that the DUAI method can overcome the low pregnancy rate of ES, despite the low motility, viability, and fertilization ability of ES.

In the present study, we examined the effect of straw size on spermatozoa motility, viability, acrosome integrity, mitochondrial membrane potential, and plasma membrane integrity after freezing-thawing. Hanwoo semen was collected from three bulls and diluted with an animal protein-free extender, divided into two groups, namely, 10 million spermatozoa in 0.25 mL and 20 million spermatozoa in 0.5 mL straw, and cryopreserved. In Experiment 1, the motility and motility parameters of the frozenthawed spermatozoa were evaluated. After freezing-thawing, the spermatozoa motility parameters fast progressive, straight line velocity, and average path velocity were compared between the 0.25 mL straw and 0.5 mL straw groups. They were 35.2 ± 1.0 and 32.3 ± 0.7%, 34.6 ± 0.7 and 31.8 ± 0.5 μm/s, 51.4 ± 1.3 and 47.1 ± 1.1 μm/s, 0.25 mL straw and 0.5 mL straw groups, respectively. In Experiment 2, the viability, acrosome membrane integrity, and mitochondrial membrane potential of the frozen-thawed spermatozoa were assessed. After freezing-thawing, the percentages of spermatozoa with live, intact acrosomes and high mitochondrial membrane potential were compared between the in 0.25 mL straw and 0.5 mL straw groups. They were 48.0 ± 2.6% and 35.6 ± 2.8% between the 0.25 mL straw and 0.5 mL straw groups. In Experiment 3, the plasma membrane integrity of frozen-thawed spermatozoa was compared. After freezingthawing, the plasma membrane integrity was higher for the in 0.25 mL straw group than the 0.5 mL straw group. They were 62.0 ± 2.2 and 54.1 ± 1.3% between the 0.25 mL straw and 0.5 mL straw groups. In conclusion, our results suggest that freezing semen in 0.25 mL straw improves the relative motility, viability, and acrosomal, mitochondrial membrane potential, and plasma membrane integrity of Hanwoo bull spermatozoa.

This present study was conducted to investigate protective effect of discontinuous Percoll gradient containing alpha-linolenic acid (ALA) before freezing process on viability, acrosome damage, mitochondrial activity, and oxidative stress of frozen-thawed boar spermatozoa. The separation of spermatozoa by discontinuous Percoll gradient was performed by different concentration of Percoll solution (45/90%) containing ALA combined with bovine serum albumin (BSA), and collected sperm in each Percoll layer was cryopreserved. To evaluate viability, acrosome damage, mitochondrial activity, and reactive oxygen species (ROS) level of frozen-thawed sperm, flow cytometry was used. Morphological abnormalities were observed under light microscope. In results, viability of sperm from 90% Percoll layer was higher than control and 45% Percoll group (p < 0.05). Separated sperm in 90% Percoll layer had lower acrosome damage and morphological abnormalities than control as well as viability, whereas 45% Percoll group was higher (p < 0.05). Similar with acrosome damage and abnormalities, mitochondrial activity was slightly enhanced and the population of live sperm with high ROS level was decreased by 90% Percoll separation, however, there was no significant difference. Supplementation of 3 ng/mL ALA into Percoll solution increased sperm viability and decreased population of live sperm with high ROS compared to control (p < 0.05). In conclusion, discontinuous Percoll gradient before freezing process could improve efficiency of cryopreservation of boar sperm through selection of sperm with high freezing resistance, and supplement of ALA during Percoll gradient might contribute suppression of ROS generation via stabilizing of plasma membrane during cryopreservation.

In this study, two epididymal spermatozoa recovery methods in relation to sperm number, motility, viability and acrosome reaction were examined. Seven bulls were castrated and 7 testicles with epididymides were transferred to the laboratoy. Epididymis in each bull was randomly used for flushing and mincing methods with semen extender (Optixcell, IMV, France). The recovered spermatozoa with adjusted sperm concentration to 40 × 106 cells/mL was diluted with optixcell and cryopreserved. In experiment 1, the difference in the total number of spermatozoa using flushing and mincing methods was insignificant (2570.0 and 2505.2 × 106 cells/mL, respectively). For experiment 2, the percentage of motile spermatozoa and motility parameters between flushing and mincing methods were studied through the use of sperm class analyzer after frozen-thawing. The percentage of total motile sperm between flushing and mincing methods was almost the same with 89.5±12.8 and 91.4±7.9%, respectively. The same is the case with experiment 3 wherein the viability and acrosomal integrity of frozen-thawed epididymal spermatozoa by flushing and mincing was insignificantly different. The results from the study showed that both flushing and mincing methods can be used for epididymal spermatozoa recovery in bull.

본 연구는 티모시 건초와 농후 사료 위주의 사료를 급여한 한우 씨수소 정소상체 정자 체외수정 효율 조사를 통해 정자의 활용 가능성을 조사하였다. 농후 사료는 체중의 1.8%를 급여하고 양질의 티모시 건초를 자유채식 시킨 14개월령 거세우의 정소에서 분리된 정소상체 미부의 정자를 회수하고 동결 흉해 후 체외수정을 실시한 결과는 다음과 같다. 웅성전핵과 자성전핵이 형성(2PN)된 난자는 정상수정으로, 1개의 전핵(1PN), Expanded Sperm Head (ESH), Polyspermy 형태는 비정상적인 수정의 형태로 평가하였다. 정상적으로 수정된 난자의 비율은 정소상체 정자의 경우 전체 침투율은 49.7% 그리고 정상적인 2PN을 가진 난자는 18.5%를 보였으며, 대조구 정자의 전체 침투율은 54.4%로서 정소상체 정자 보다 높은 결과를 보였으나 유의적인 차이를 보이지는 않았다. 정상적으로 2PN을 형성한 비율은 36.7%로서 정소상체 정자를 이용한 정자 보다 높았으나 유의적인 차이는 없었다. 체외수정 후 발달률 조사에서 정소 상체 정자의 분할률은 81.2%, 대조구 정자는 82.7%로 유사한 결과를 보였으나, 배반포 발달률은 정소상체 정자 24.4%와 대조구 정자 12.2%로 정소상체 정자를 사용한 난자의 발달에서는 유의적으로 높았다(p<0.05).

Purpose The Jeju black cattle are a type of traditional Korean native cattle with a characteristic black fur that covers the entire body. The Jeju black cattle are rare breed and designated as national natural monuments in 2013. It is necessary to improve reproductive techniques for the preservation and proliferation of Jeju black cattle. Methionine acts as a precursor amino acid for glutathione in protection of cells from oxidative damage, and plays a vital role in detoxification. Low sperm motility causes infertility because when sperm do not have progressive motility, it was unable to reach the ovum. The purpose on this study was to investigate whether intake of L-methionine improves sperm motility and fertility. Materials and Methods 6 Jeju black cattles over 10 years of age are raised in Subtropical Livestock Research Institute, National Institute of Animal Science, RDA. 6 Jeju black cattles was fed with L-methionine with 10g/day during 6 weeks. Semen of Jeju black cattle were collected by artificial vaginal technique. Collected sperm was diluted with AndroMed® extender and cryopreserved in 0.5 ml French straws. Fresh and freeze-thawed sperm viability and motility were evaluated by CASA. Results The viability and progressive motility of fresh spermatozoa(live spermatozoa means: from 74.41% to 80.22%, progressive motility means: from 80.60% to 95.40%) and freeze-thawed spermatozoa(live spermatozoa means: from 51.26% to 62.05%, progressive motility: from 29.68% to 45.44%) incresed after L-methionine ingestion. Conclusion The intake of L-methionine in genetically valuable cattle over 10 years of age seems to be useful for improving sperm function.

Bisphenol A (BPA), an endocrine-disrupting chemical, has received tremendous attention in the past few decades because of its detrimental health effects. Growing evidence supports that BPA is capable to alter the reproductive performance of the exposed individual. In spermatozoa, it has been reported that BPA increased oxidative stress by the overproduction of reactive oxygen species (ROS), subsequently affects the sperm function, biochemical properties, and fertility. Since antioxidants minimize cellular oxidative stress, therefore may have protective effects against BPA-induced stress. In the present study, we incubated mice spermatozoa for 6 h in a condition that support in vitro fertilization. The sperm incubation media was additionally supplemented with either BPA or BPA together with antioxidants, such as glutathione, vitamin C, and vitamin E. Our results showed that antioxidant significantly decreased the production of ROS that subsequently supports motility and acrosomal integrity of BPA-exposed spermatozoa. Particularly, glutathione and vitamin E inhibit protein kinase-A dependent phosphorylation of sperm proteins subsequently prevented precocious acrosome reaction. In addition, both antioxidants were found to restore fertilization and early embryo development potentiality of BPA-exposed spermatozoa. Therefore, we conclude that antioxidants minimize oxidative stress in spermatozoa in a BPA containing micro-environment, thus avoiding BPA-mediated harmful consequences. The current finding has both theoretical and clinical significance for developing potential remedies of the BPA toxicity.

The ability of conventional semen analysis to predict male fertility is questionable. Since the prediction of male fertility is extremely of importance for the artificial insemination and profitable farm managements in animals, the development of highly sensitive biomarker of male fertility is a prime concern. Porcine Seminal Protein I (PSP-I) and Porcine Seminal Protein II (PSP-II) have been known that they are related with motility, and viability of spermatozoa. Thus, we investigated PSP-I and PSP-II level in boar spermatozoa to predict boar’s fertility. The expressions of PSP-I and PSP-II in spermatozoa from 21 individual boars with different fertility and litter size (litter size ranges from 10.3 – 14.2) were examined using qRT-PCR. Litter size was determined in 530 saws after artificial insemination (AI). In addition, sperm motility, motion kinematics, and capacitation status were measured using computer-assisted sperm analysis and Hoechst 33258/chlortetracycline fluorescence staining, respectively. PSP-I and PSP-II showed significantly negative correlation with litter size (r=0.578; P=0.006 and r=0.456; P=0.038, respectively). Furthermore, receiver-operating curves (ROC) was used to determine the accuracy for the prediction of boar fertility. Therefore we divided into 2 groups based on the median value of litter size. When selecting higher litter size group, PSP-I can predict litter size with overall accuracy 90.48% (sensitivity 88.89, specificity 91.67, negative predictive value 91.67, and positive predictive value 88.89) and PSP-II can predict with overall accuracy 81.82% (sensitivity 55.56, specificity 100.00, negative predictive value 76.47, and positive predictive value 100.00). Interestingly, PSP-I and PSP-II were found to increase 0.76 pups than average litter size (average 12.48) in tested boars. To best of our knowledge, this study is the first trial to investigate the correlation between PSP-I, PSP-II, and litter size. Therefore, we suggest that PSP-I and PSP-II could be considered as promising biomarkers for predicting male fertility and litter size outcome in field condition.

In this study, we examined sperm penetration and blastocyst developmental rate of oocytes to determine fertilizability of cauda epididymal spermatozoa in Hanwoo bull. One testicle with epididymides were castrated from one Hanwoo bull (14 months of age) and transported to laboratory. Spermatozoa recovered from cauda epididymis by mincing with semen extender (Optixcell, IMV, France) and cryporeserved in liquid nitrogen tank until use. As control, frozen Hanwoo semen was used. Cumulus oocyte complexes (COCs) were collected from follicles (2-8 mm) of slaughtered ovaries and 10 to15 COCs were matured in 50μl droplet with M-199 media supplemented with 10% fetal bovine serum, 10μg/ml FSH, 10μg/ml LH, 10μg/ml EGF for 22 to 24 hours in a humidified atmosphere of 5% CO2 in air. After maturation of COCs, matured COCs were co-incubated with cauda epididymal spermatozoa in 100μl droplet in modified Brackett and Oliphant media supplemented with 2.5 mM theophylline for 12 or 18 hours under 5% CO2 in air. Sperm concentration was adjusted to 5 × 106cells/ml. After IVF for 18 hours, presumptive zygotes were cultured in modified synthetic oviductal fluid with 1mM glutamine, 12 essential amino acids, 10 μg/ml insulin under 5% CO2, 5% O2 in air. In experiment 1, we examined sperm penetration rate at 12 hours of IVF of frozen-thawed epididymal sperm. Total penetration rate among cauda epididymis and control were not significantly different (mean±standard error, cauda epididymis and control vs. 49.7±11.3 and 54.4±12.8%) In experiment 2, cleavage and blastocyst development rate were evaluated at day 2 and day 8 after IVF for 18 hours. Cleavage rate among cauda epididymis and control was similar different (cauda epididymis and control vs. 81.2±3.4 and 82.7±2.5%). However, blastocyst developmental rate of cauda epididymis group was significantly higher than that of control group (cauda epididymis and control vs. 24.4±1.6 and 12.2±2.8%, p<0.05). In conclusion, cauda epididymal spermatozoa in Hanwoo bull has high fertilizability and embryo development. Cauda epididymal sperm can be used as an alternative to ejaculated frozen sperm in vitro.

The aim of this study was to develop a chemically defined extender for dog sperm cryopreservation by supplementation of essential and non-essential amino acids solution in EY-free PVA extender. Spermatozoa collected from mature dogs (1 ｘ 108 cell/ml) were frozen with EY-free extender supplemented with 0 (control), 1, 2, 4 % essential amino acids (EAAs) or 1, 2, 4 % non-essential amino acids (NEAAs). Sperm progressive motility, viability and acrosome integrity were evaluated immediately after thawing at 37 ℃ for 25 s and post-thaw incubation at room temperature for 20 min. In addition, to evaluate the synergistic effect of EAAs and NEAAs, spermatozoa were frozen with 0, 0.5, 1 or 2 % EAAs-NEAAs mixture (v:v). Sperm progressive motility, viability and acrosome integrity were evaluated immediately after thawing and post-thaw incubation. Additionally, spermatozoa were frozen using EY-free PVA extender supplemented with 2 % EAAs, 2 % NEAAs or 0.5 % EAAs-NEAAs mixture. The ROS level and phosphatidylserine (PS) translocation (Annexin V-FITC assay) were assessed using flow cytometry. In addition, gene expression level for SMCP (motility-related), apoptosis-related BCL2 and BAX was measured after freezing-thawing. The progressive motility of spermatozoa cryopreserved in EAAs or NEAAs significantly increased (P < 0.05) in all groups compared to the control group regardless of thawing conditions. In addition, 1 % NEAAs significantly protected the acrosome membrane of spermatozoa after freezing-thawing (P < 0.05). However, EAAs has shown no significant effect on viability and acrosome membrane integrity of spermatozoa. On the other hand, addition of EAAs-NEAAs mixture to EY-free PVA extender significantly (P < 0.05) increased sperm progressive motility without any effect on viability. Supplementation of 0.5 % EAAs-NEAAs mixture significantly (P < 0.05) increased the expression level of SMCP, BCL2 and BAX compared to control without significant effect on PS translocation and ROS level. We conclude that essential and non-essential amino acids solution can be effectively used in EY-free extender to improve sperm motility, acrosome integrity and gene expression of SMCP and BCL2 in dog sperm cryopreservation.

In this study, we examined total number, motility and plasma membrane integrity of epididymal spermatozoa from cauda epididymis of bull after preservation at 4ºC. Totally, 23 testicles were castrated from 23 bulls (mean±standard error, age of days = 426.0±7.3, body weight (kg) = 379.7±8.4, scrotal circumference (cm) = 31.0±0.4) at Hanwoo Research Institute, NIAS, and transported to laboratory and preserved on 1, 4 and 6 days at 4 ºC. As control, epididymal spermatozoa recovery from 7 testicles was conducted after transportation to laboratory immediately. In experiment 1, we compared total number of spermatozoa among groups. Total number of spermatozoa from epididymis was not significantly on different preservation day of 0, 1, 4 and 6 which is 1778.0±304.7, 1824.8±343.9, 1228.4±91.7, 1201.8±178.6×106 cells/ml, respectively). In experiment 2, we examined spermatozoa motility and motility parameters (VCL (μm/s), VSL (μm/s), VAP (μm/s), LIN (%)) by computer assisted sperm analysis (SCA, MicroOptic) system. Percentage of motile on 0 and 1 day (88.9±5.2 and 85.8±6.1) was significantly higher than that on 4 and 6 days (32.6±6.5 and 34.3±8.25). Percentage of VCL (μm/s) on 0 and 1 day (93.5±7.6 and 83.0±14.9) was significantly higher than that on 4 and 6 days (36.6±5.1 and 39.5±5.5) (p<0.05). Percentage of VSL (μm/s) on 0 day (28.0±2.1) was significantly higher than that on 1, 4 and 6 days (20.2±3.0, 9.0±2.0 and 8.5±1.6, p<0.05). Percentage of VAP (μm/s) on 0 and 1 days (49.4±3.8 and 41.3±6.6) was significantly higher than that on 4 and 6 days (18.2±3.0 and 19.3±2.8, p<0.05). Percentage of LIN (%) on 0 day (30.7±2.6) was significantly higher than that on 4 and 6 days (23.4±2.7 and 21.1±1.0, p<0.05). Motility of spermatozoa was divided into 4 groups (fast progresive, slow progressive, non-progressive and immotile) based on WHO guideline. Percentage of fast progressive on day at 0 was significantly higher than that on 1, 4 and 6 days (0, 1, 4 and 6 days vs. 19.8±1.9, 10.2±1.1, 2.6±1.0 and 2.3±1.2%, respectively). In conclusion, cauda epididymal spermatozoa should be recovered within one day after preservation at 4 ºC to recover high quality of epididymal spermatozoa in Hanwoo bull

Sperm cryopreservation is well known as a valuable method to preserve the genetic traits. Although many studies have established semen cryopreservation protocols, lack of studies were conducted to discover the differences of sperm proteome and functions between ejaculated and epididymal spermatozoa following to cryopreservation. Therefore, the objective of this study was to (i) evaluate the effect of cryopreservation on bull epididymal spermatozoa and (ii) discover the potential biomarkers, which have highly tolerance to freezing on bull epididymal spermatozoa. Our preliminary study demonstrated that spermatozoa from each bulls have different resistance on freezing during cryopreservation. We divided spermatozoa into two groups according to sperm motility following to cryopreservation; high freezing-tolerant spermatozoa (HFS) and low freezing-tolerant spermatozoa (LFS). Several sperm functional parameters, i.e. sperm motility/motion kinematics, speed parameters, viability, mitochondrial membrane potential, and capacitation status. Our results showed that all parameters except for motion kinematics and capacitation status had significant differences between HFS and LFS. Subsequently, two dimensional electrophoresis were conducted to compare the expression levels of sperm proteome between both groups. Three proteins {glutathione s-transferase mu 5 (GSTM5), voltage-dependent anion-selective channel protein 2 (VDAC2), and ATP stynthase subunit beta (ATP1B1)} were differentially expressed. Based on these results, we propose that epididymal spermatozoa from individual bull have different freezability upon cryopreservation and three differentially expressed proteins might be selected as a biomarker to predict high freezing-tolerant epididymal spermatozoa.

Sperm cryopreservation preserves genetic resources for animal breeding and for human patients who suffers from permanent testicular damage. Although the sperm cryopreservation has been used for many years, the addition of cryoprotective agent (CPA) during cryopreservation negatively affects sperm function and quality. Our previous study reported that the addition of CPA reduced bull sperm physiological functions. However, the sperm cells collected from individual bulls presented different sensitivity to the damage induced by CPA. In the present study, we examined if CPA affect sperm cells acquired from individual bulls. Individual bull spermatozoa were divided into two groups based on motility parameters; high CPA-tolerant sperm (HCS) and low CPA-tolerant sperm (LCS). Our results showed that the HCS group presented good physiological function after CPA exposure, whereas the LCS group showed a significant decrease in the sperm function. We also found differentially expressed five proteins between the HCS and LCS groups, which refer to cytosolic 5′-nucleotidase 1B (NT5C1B), fumarate hydratase (FH), F-actin-capping protein subunit beta (CAPZB), voltage-dependent anion-selective channel protein 2 (VDAC2), and cytochrome b-c1 complex subunit 1 (UQCRC1). NT5C1B and FH showed abundant expression in the HCS group, while the expression of CAPZB, VDAC2, and UQCRC1 was relatively lower in the HCS group than in the LCS group. The current results suggest that NT5C1B, FH, CAPZB, VDAC2, and UQCRC1 can be used as potential markers to predict CPA-tolerable spermatozoa. Those markers provide a reliable tool to select animals and breeds with CPA tolerance.

The purpose of this study was to establish an optimal storage temperature and characteristic analysis after frozen-thawed dairy goat sperm. Sperm was collected at Chojeong dairy goat farm using an electric stimulator and dilluted with semen washing media. The egg yolk-triladyl frozen solution was used for the freezing of Saanen dairy goat sperm and the freezing concentration was set to 1×108sperm/ml. The frozen sperm were thawed in water bath at 37.5℃ for 45 seconds and motility was measured after preservation for 0, 30, 60, 90 and 120 min at 4℃, 17℃ and 37℃, respectively. Sperm characteristic analysis was conducted by flow cytometry. In results, sperm motility at 30, 60, 90 and 120 min after thawing was significantly higher in 17℃ than 4℃ and 37℃ (p<0.05). On the other hand, the frozen-thawed sperm motility were gradually decreased with storage periods increased (30, 60, 90 and 120 min) at 4℃, 17℃ and 37℃. Viability(42%), acrosome damage(24%), mitochondrial damage(28%) and ROS level(4%) were analyzed by flow cytometry in frozen-thawed spermatozoa in 7 male dairy goats. In summary, the motility of frozen-thawed spermatozoa in Saanen dairy goat was more efficient for storage 17℃. The average of viability 42%(30%~54%), acrosome damage 24%(16%~33%), mitochondrial damage 28%(20%~54%) and ROS level 4%(3%~6%) were arranged as standard value by 7 male dairy goats. However, more researches are needed to establish the optimal conditions or proper supplementation for sperm preservation. This study was carried out with the support of research project on feasibility study of the research & development projects for activating the hillside livestock farming and the development of goat grazing program of Rural Development Administration by Korea government (2018PJ013546).

Cryopreservation is mainly used for preservation of boar sperm. However, this method stresses the sperm by reactive oxygen species (ROS), and the conception rate and the litter size are not more efficient than the liquid preservation of spermatozoa. Therefore, we use chitosan which is a natural product derived antioxidant compound. We used GnHA and GnHG as chitosan complexes to cryopreserve boar sperm for improve sperm metabolism and function. Sperm parameter (sperm motility, progressive motility, path velocity, straight-line velocity, curvilinear velocity) is measured by computer-assisted sperm analysis (CASA) using frozen sperm with GnHA or GnHG (0, 0.25, 0.5, 1 mg/mL). Also, lipid peroxidation analysis using malondialdehyde (MDA) is performed to confirm the antioxidative effect of chitosan in frozen spermatozoa. Sperm motility was higher in GnHA 0.25 mg/mL and GnHG 0.5 mg/mL compared to control. In addition, GnHG 0.5 mg/mL was significantly decreased in lipid peroxidation analysis. The results suggest that GnHA and GnHG are effective for boar sperm cryopreservation by antioxidant effect.

The cryopreservation has been extensively applied in many cells including spermatozoa (semen) during past several decades. Especially, the canine spermatozoa cryopreservation has contributed on generation of progeny of rare/genetically valuable dog breeds, genome resource banking and transportation of male germplasm at a distant place. However, severe and irreversible damages to the spermatozoa during cryopreservation procedures such as the thermal shock (cold shock), formation of intracellular ice crystals, osmotic shock, stress of cryoprotectants and generator of reactive oxygen species (ROS) have been addressed. According as a number of researches have been conducted to overcome these problems and to advance cryopreservation technique, several analytical methods have been employed to evaluate the quality of the fresh or cryopreserved canine spermatozoa in regards to the motility, morphology, integrity of membrane and DNA, mitochondrial activity, ROS generation, binding affinity to oocytes, in vitro fertilization potential and fertility potential by artificial insemination. Because the study designs with certain application of analytical methods are selective and varied depending on each experimental objective and laboratory condition, it is necessary to establish the normal reference data of the fresh or cryopreserved canine spermatozoa for each analytical method to monitor experimental procedure, to translate raw data and to discuss results. Here, we reviewed the recent articles to introduce various analytical methods for the canine spermatozoa as well as to establish the normal reference data for each analytical method in the fresh or cryopreserved canine spermatozoa, based on the results of the previous articles. We hope that this review contributes to the advancement of cryobiology in canine spermatozoa.