Seminal plasma proteins as modulators of the sperm function and their application in sperm biotechnologies

Seminal plasma (SP) is known to play an important role in mammalian fertilization. However, the variability found in its composition among species, males and even fractions of the same ejaculate has made difficult to completely understand its effect in sperm function. Proteins are one of the major SP components that modulate sperm functionality. During the last years, intensive work has been performed to characterize the role of these proteins. They have been found to influence sperm capacitation, formation of the oviductal sperm reservoir and sperm-oocyte interaction. Sperm biotechnologies, such as sperm cryopreservation and flow cytometric sex-sorting, that involve a substantial dilution of the SP are detrimental to sperm quality. Attempts to improve the outcome of these biotechnologies include the restoration of SP, which has produced contradictory results. To overcome this variability, different research groups have proposed the application of isolated SP proteins. Herein, we will review the current knowledge in the role of the major SP proteins as modulators of sperm functionality. Furthermore, we will discuss the possible applications of the SP proteins in sperm cryopreservation and flow cytometric sex-sorting.

Non-surgical deep intrauterine transfer of superfine open pulled straw (SOPS)-vitrified porcine embryos: evaluation of critical steps of the procedure

Previous trials achieved extremely poor results when using the one-step warming method in a syringe in combination with non-surgical deep intrauterine transfer (NET) of superfine open pulled straw (SOPS)-vitrified embryos. This study aimed to assess the effect of the warming procedure on the in vitro and in vivo development of SOPS-vitrified embryos. The effect of the passage of the vitrified-warmed (VW) embryos through the NET catheter was also evaluated. Groups of 4 to 6 morulae and blastocysts, collected from weaned sows, were SOPS-vitrified in 1 μL of vitrification medium, warmed by the one-step warming method in a dish or in a 1-mL syringe and cultured in vitro for 48 h to evaluate the embryo survival (ES) and hatching rates (HR). Warming in syringe had a deleterious effect (P < 0.05) on the in vitro ES (60.5 ± 10.4%) and HR (39.6 ± 9.5%) of VW embryos in comparison with embryos warmed in a dish (85.4 ± 10.6% and 69.0 ± 8.4%, respectively). This decreased embryonic development was due to the increased time required between the removal of the straws from the liquid nitrogen and the contact of the embryos with the warming medium when the warming was performed in a syringe in comparison with that for the warming in a dish. After verifying that the passage of VW embryos through the NET catheter does not have a damaging effect on their further in vitro development, the negative effect of warming in a syringe was also confirmed after NET. Fifteen fresh and SOPS-vitrified embryos warmed in a syringe or in a dish were transferred to each recipient (n = 28) and recovered 24 h later to assess their developmental progression. All embryos from the syringe group were found to have degenerated at recovery. The in vivo ES and HR from the dish group (80.4 ± 3.4% and 14.2 ± 7.2%, respectively) were lower (P < 0.05) than those from the fresh group (94.0 ± 4.1% and 36.8 ± 7.8%, respectively). Combining the warming in a dish and the NET procedure, 35 VW embryos were transferred to each of 10 gilts. Five recipients farrowed an average of 10.4 ± 0.9 piglets. In conclusion, the method of one-step warming in a syringe has a negative effect on the in vitro and in vivo viability of SOPS-vitrified porcine embryos. In addition, NET of SOPS-vitrified embryos warmed by the one-step method in a dish showed promising reproductive performance of recipients. However, despite the great potential of this technology, further developments are required for large-scale commercial applications.

106 THE WARMING PROCEDURE: A FIRST STEP FOR IMPROVING THE NONSURGICAL DEEP INTRAUTERINE TRANSFER OF SOPS-VITRIFIED PORCINE EMBRYOS

We previously reported successful nonsurgical deep intrauterine embryo transfer (ET) of fresh in vivo–derived porcine embryos. However, several trials from our laboratory demonstrated that when this procedure was used in combination with vitrified/warmed (VW) embryos, its efficiency was very low. Recently, we have shown that the one-step warming method in syringe, which was used in the earlier trials, compromises the in vitro embryo viability. The aim of this study was to confirm the negative effect of the direct warming in syringe and to evaluate the effect of alternative warming procedures on the in vivo development of VW embryos after nonsurgical ET. In Experiment 1, morulae and early blastocysts were collected on Days 5 to 6 (Day 0: onset of oestrus) and assigned to one of the following groups: 1) syringe group: vitrified embryos (n = 88) were warmed by the one-step method directly in a 1-mL syringe containing 300 μL of warming medium, which was connected to the ET catheter and then transferred to recipients (n = 6); 2) dish group: vitrified embryos (n = 194) were warmed with one-step warming method in a Petri dish containing 1 mL of warming medium, loaded into a Tom Cat catheter and transferred to recipients (n = 13); and 3) control group: fresh embryos (n = 129) were loaded in a 1-mL syringe in 100 μL of transfer medium and transferred to 9 recipients. An average of 15 embryos were transferred to each recipient on Day 4 or 5. Embryos were surgically recovered 24 h after ET. Data were analysed by ANOVA. The embryo recovery rate was similar among groups (range: 70.7 ± 4.8% to 77.2 ± 6.5%). The embryo survival (ES) and the hatching rate (HR) from the control group (94.0 ± 2.1% and 33.4 ± 7.6%, respectively) were higher (P ≤ 0.05) than those from the dish group (80.4 ± 4.6% and 14.5 ± 4.1%, respectively). All embryos from the syringe group were degenerated. Some viable recovered embryos (n = 135) were cultured for 48 h to evaluate their subsequent in vitro development. No differences were observed in ES between the control and the dish group (100.0 ± 0.0% vs 98.9 ± 1.0%). The HR in the control group (71.5 ± 2.1%) was higher (P ≤ 0.01) than that of the dish group (42.7 ± 6.1%). In experiment 2 we evaluated the reproductive performance of naturally cycling recipients after nonsurgical ET of vitrified embryos warmed with the one-step method in a Petri dish. An average of 35 VW morulae and blastocysts were transferred to each recipient (n = 10) on Days 4 to 6. Four recipients returned to oestrus at Days 21 to 22. The remaining 6 recipients were diagnosed pregnant by ultrasonography on Day 26. At Days 50 to 55, 5 recipients remained pregnant. In conclusion, the one-step in syringe warming method for vitrified porcine embryos had a completely adverse effect on the vivo viability, whereas nonsurgical ET of embryos warmed in a Petri dish allowed us to obtain promising reproductive performance. Supported by MICINN (AGL2009-12091) and SENECA (GERM 04543/07).

Unusual systemic metastases of malignant seminoma in a dog

Unilateral enlargement of left testicle and scrotum was detected in an 8-year-old West Highland White Terrier. The histopathological diagnosis after surgery was a seminoma (SEM) tumour, and a diagnosis of metastatic foci was also detected in vaginal tunic and scrotum. Two months later, new metastatic SEM foci in the skin were diagnosed. Twenty-two months after the initial orchiectomy new multiple cutaneous nodules and a swelling of periesophageal structures were observed. Finally, the necropsy revealed multiple malignant metastatic SEM focus. To the author's knowledge, this is the first description of a canine SEM with unusual widespread metastasis on the base of tongue, soft palate, trachea and pericardium.

90 OPEN PULLED STRAW VITRIFICATION OF IN VITRO PORCINE BLASTOCYTS IN A CHEMICALLY DEFINED MEDIUM

The aim of this study was to design a chemically defined medium for the vitrification of in vitro produced porcine blastocysts avoiding the use of serum or serum components. Cumulus–oocyte complexes were matured in vitro in NCSU-23 for 44 h and were inseminated with frozen–thawed spermatozoa. Presumptive zygotes were cultured for 16 h to assess in vitro fertilization (IVF) parameters (N = 200) or for 6 days (N = 600) in order to obtain blastocysts. For chemically delipidation, 10 μM forskolin was added to the culture medium on Day 5 of in vitro culture. On Day 2, embryos were evaluated for cleavage rate. On Day 6, embryos were assessed for blastocyst formation; only those blastocysts showing excellent morphological appearance were selected for vitrification. Blastocysts were vitrified using as basic medium TCM-199 HEPES supplemented with 20% of newborn calf serum (NBCS; n = 65), with 0.1% of polyvinyl alcohol (PVA; n = 64) or without additives (WA; n = 65). The OPS-vitrification and warming were performed as described by (Sanchez-Osorio et al. 2010 Theriogenology 73, 300–308) using 16% of Etylenglycol and 16% of dimetyl sulfoxide as final concentrations of cryoprotectants. Vitrified blastocysts were warmed and cultured in vitro for 24 h to assess their viability. Blastocysts that totally reformed their blastocoel cavity showing a normal or excellent morphology were considered viable. In addition, after in vitro culture vitrified-warmed viable embryos were fixed in 4% paraformaldehyde in PBS medium and stained with Hoechst 33342 in order to assess the total number of cells. Data were analysed by using the MIXED procedure of SPSS. The threshold for significance was set at P < 0.05. Results are expressed as least squares means ± SEM. The maturation, penetration, and monospermy rates were 98.5 ± 1.2%, 85.3 ± 3.6%, and 48.8 ± 5%, respectively. The efficiency of IVF (defined as the ratio of monospermic oocytes to the total number of inseminated oocytes) was 41.0 ± 4.9%. The values of cleavage rate at Day 2 and blastocysts formation rate were 67.8 ± 1.4% and 37.3 ± 1.6%, respectively. After vitrification and warming, similar survival rates were observed for NBCS (33.8 ± 5.9) PVA (40.6 ± 6.0), and WA (30.8 ± 5.9) groups. No significant differences were found for the total number of cells (ranged from 35.4 ± 6.8 to 50.8 ± 8.3) among vitrification groups. In conclusion, in vitro derived porcine blastocysts can be vitrified in the absence of serum and serum components. Furthermore, PVA is a suitable substitute for serum in vitrification solutions with no detrimental effect on the viability of in vitro produced pig blastocysts. This study was supported by the Seneca foundation of Murcia (GERM 04543/07).

Superfine open pulled straws vitrification of porcine blastocysts does not require pretreatment with cytochalasin B and/or centrifugation

The present study investigated the in vitro development of and cytoskeletal disruption suffered by in vivo-derived porcine blastocysts subjected to superfine open pulled straws (SOPS) vitrification. Blastocysts were either untreated prior to SOPS vitrification or were subjected to one of the following three pretreatment protocols: (1) centrifugation (12 min, 13 000g); (2) 25 min equilibration with 7.5 μg mL–1 cytochalasin B; or (3) equilibration with cytochalasin B followed by centrifugation. After 24 h culture, fresh (n = 32) and vitrified–warmed (n = 188) blastocysts were evaluated by stereomicroscopy, with survival and hatching rates recorded. Some blastocysts were stained with 4′,6′-diamidino-2-phenylindole and processed for cytoskeletal evaluation. Three cytoskeletal patterns were identified: Grade I, intact cytoskeleton; Grade II, gross maintenance of integrity, but with some clumps of actin within the cytoplasm; and Grade III, a highly disrupted cytoskeleton. There were no differences in the survival, hatching and cell death rats, total cell number or cytoskeletal integrity between the different vitrification groups. Cell death was greater for vitrified blastocysts than for fresh blastocysts (3.6 ± 0.4% v. 0.4 ± 0.7%, respectively; P < 0.05) and the percentage of blastocysts with a Grade I cytoskeletal pattern was lower for vitrified compared with fresh blastocysts (60.8% v. 92%, respectively; P < 0.05). The vitrified–warmed blastocysts that hatched during culture exhibited a Grade I cytoskeletal pattern. In conclusion, successful SOPS vitrification of porcine blastocysts does not require pretreatment with cytochalasin B and/or centrifugation.

Vitrification and warming of in vivo-derived porcine embryos in a chemically defined medium

The aim of this study was to design a protocol for vitrification and warming of porcine embryos in a chemically defined medium. A total of 663 morulae and blastocysts were collected from weaned crossbred sows (Large White-Landrace) 5 to 6 d after estrus and vitrified with the Superfine Open Pulled Straw method. In Experiment 1, embryos were vitrified using as a basic medium TCM-199-HEPES supplemented with 20% newborn calf serum (NBCS) or with 0, 0.1%, 0.5%, or 1% polyvinyl alcohol (PVA). Nonvitrified embryos were used as a fresh control group. Survival and hatching rates were evaluated after 72 h of in vitro culture to assess embryo viability. In addition, some hatched blastocysts derived from morulae and blastocysts were processed to determine the total cell number and the cell proliferating index as measures of their quality. Within each stage of embryo development, the different vitrification groups and the fresh control group showed similar high embryo survival (range, 70.5+/-7.1% to 84.9+/-8.1% and 85.3+/-8.1% to 98.4+/-8.2% for morulae and blastocysts, respectively) and hatching rate (range, 46.3+/-10.1% to 66.7+/-11.2% and 73.7+/-11.3% to 89.4+/-11.2% for morulae and blastocysts, respectively) and quality after in vitro culture. In Experiment 2, embryos were vitrified using 0.1% PVA and warmed with TCM-199-HEPES-0.13 M sucrose supplemented with 20% NBCS or either 0 or 0.1% PVA. Nonvitrified embryos were used as a fresh control group. As in Experiment 1, no significant differences were detected in embryo survival (range, 67.9+/-6.6% to 74.5+/-6.6% and 91.9+/-7.0% to 99.5+/-6.3% for morulae and blastocysts, respectively) and hatching rate (range, 47.0+/-7.2% to 64.8+/-9.9% and 89.4+/-7.4% to 98.2+/-6.9% for morulae and blastocysts, respectively) and quality among the warming groups or among vitrified and fresh control embryos. In both experiments, the developmental embryo stage influenced the survival and hatching rates, as well as the number of cells (P<0.01), with the blastocyst stage yielding the best results. In conclusion, PVA can be used as a substitute for serum in vitrification and warming solutions without detrimental effects on the in vitro development of in vivo-derived porcine morulae and blastocysts.

Improving the efficiency of insemination with sex-sorted spermatozoa

The sorting of X- and Y-chromosome-bearing spermatozoa by flow cytometry is nowadays one of the most apt assisted-reproduction technologies in livestock production. Potential economic and biological benefits, as well as those related to easier management of herds, have been reported arising out of the application of this technique, especially in cattle. Yet, the sex-sorting procedure induces damage to spermatozoa, affecting their function and fertilizing ability. Different species present varying degrees of susceptibility to damage from the sorting process and each has its own requirements for sex-sorted insemination procedures. Thus, several new protocols and strategies have been designed for the handling of sorted spermatozoa, with the main objective of optimizing their fertilizing ability and the consequent application of flow-cytometric sex-sorting technology. This article reviews current advances in this technology, pointing out the components to be improved before this technology may be widely applied in different domestic species.

Optimal characteristics of spermatozoa for semen technologies in pigs

Despite the great potential of sperm technologies such as sperm cryopreservation and sperm sex sorting for the improvement of different aspects of swine production, artificial insemination with fresh or stored semen is currently the only sperm technology used at a commercial scale in the pig industry. The lower reproductive performance associated with the use of these sperm technologies is the reason for such limited use. Since optimal characteristics are required for successful application of frozen-thawed and sex-sorted boar spermatozoa, the present paper summarises the value of the current available methods for their functional assessment as well as the effects of these technologies on boar sperm functionality. In addition, strategies developed to reduce sperm damage and improve the yields of both sperm technologies in swine production are also reviewed with particular attention to the contributions of the authors.

Localization and expression of spermadhesin PSP-I/PSP-II subunits in the reproductive organs of the boar

The epithelial localization and expression of the spermadhesin PSP-I and PSP-II subunits were determined in the testis, ductus epididymes (caput, corpus and cauda), seminal vesicles and bulbourethral glands of mature boars, using immunohistochemical, western blotting and RT-PCR methods. Immunohistochemistry showed positive labelling for PSP-I and PSP-II antibodies in the epithelium of seminal vesicles in all males tested. Positive immunolabelling, but with variable intensity, was also present in the epididymal epithelium (caput, corpus and cauda), although varying largely among segments and boars. Immunoreactivity was nearly or completely absent in the seminiferous epithelium and the bulbourethral gland, although SDS-PAGE and western blotting revealed the presence of PSP-I and PSP-II immunoreactive bands in all the tissue extracts, including the testis and the bulbourethral gland. mRNA amplification by RT-PCR using primers specific for PSP-I and PSP-II showed a trend similar to that observed for western blotting, i.e. intensity variation between tissues (even between segments of the same epididymis) and among boars. Our results indicate that the seminal vesicles are the main source of PSP-I and PSP-II spermadhesins, although epididymal segments, testis and the bulbourethral gland also participate in the expression of both proteins.

Effects of ultrashort gamete co-incubation time on porcine in vitro fertilization

A reduction in co-incubation time has been suggested as an alternative method to reduce polyspermic fertilization. The aim of this study was to evaluate the effect of short periods of gamete co-incubation during pig in vitro fertilization. A total of 2,833 in vitro matured oocytes were inseminated with thawed spermatozoa and coincubated for 0.25, 1, 2, 3, 7, 10 min and 6h. The oocytes from the 0.25-10 min groups were washed three times in modified Tris-buffered medium (mTBM) medium to remove spermatozoa not bound to the zona and transferred to the same medium (containing no spermatozoa) until 6h of co-incubation time were completed. After 6h, presumptive zygotes from each group were cultured in NCSU-23 medium for 12-15 h to assess fertilization parameters. After each period of co-incubation, 45-50 oocytes from each group were stained with Hoechst-33342 and the number of spermatozoa bound to the zona was counted. Although the number of zona bound spermatozoa increased (p<0.05) with the co-incubation time, no increase was observed in penetration rates among groups from 2 min to 6h of co-incubation time (ranging from 53.5+/-2.8 to 61.3+/-2.6%). Similarly, the efficiency of fertilization reached a maximum for the 2 min of co-incubation group with values ranging between 32.3+/-2.4 and 41.9+/-2.5%. The reduction of co-incubation time did not affect the monospermy rate (range: 71.3+/-3.4-80.2+/-3.8%) and the mean number of spermatozoa/oocyte (range: 1.2+/-0.4-1.4+/-0.5). These results show that, under our in vitro conditions, high penetration rate can be obtained with co-incubation times as short as 2 min, although monospermy could not be improved using this strategy.

Factors affecting the success rate of porcine embryo vitrification by the Open Pulled Straw method

The objectives of this study were: (1) to evaluate the influence of porcine embryo developmental stage on in vitro embryo development after vitrification, (2) to study the efficiency of the one-step dilution procedure, compared with conventional warming, for vitrified embryos at different stages of development, and (3) to determine the influence of the embryo donor on the in vitro survival of vitrified embryos at morulae and blastocyst stages. Two to four cell embryos, morulae and blastocysts were collected by laparotomy from weaned crossbred sows (n=55). Vitrification and conventional warming were performed using the OPS procedure with Superfine Open Pulled Straws (SOPS). For one-step dilution, embryos were placed in 800 microl TCM199-HEPES containing 20% of new born calf serum and 0.13 M sucrose for 5 min. To evaluate development, two to four cell embryos, morulae and blastocysts were cultured in vitro for 120, 48 and 24h, respectively. Some fresh embryos from each developmental stage were not vitrified and cultured as controls. Embryos were morphologically evaluated for their developmental capacity during the in vitro culture by stereomicroscopy. The total cell number of embryos was assessed by Hoechst-33342 staining and fluorescence microscope observation. There was a significant effect of the stage of development on the in vitro survival, perihatching rate and the number of cells of embryos after vitrification and warming (Experiment 1; p<0.001). The survival and perihatching rates of two to four cell embryos were lower than those obtained for morulae and blastocysts (p<0.001). No differences (p>0.05) in survival rates were found between vitrified and fresh blastocysts. The warming procedure did not affect the development and total cell number of vitrified two to four cell embryos, morulae or blastocysts (Experiment 2). However, donor had a significant effect (p<0.001) on the in vitro development and the number of cells of morulae and blastocysts after vitrification and warming (Experiment 3). In conclusion, the embryo developmental stage and the embryo donor were important factors that affected the development of porcine embryos after OPS-vitrification and warming. OPS-vitrification and the one-step dilution are efficient procedures to be used with intact porcine morulae and blastocysts.