Boar sperm motility is modulated by CCK at a low concentration of bicarbonate under capacitation conditions

In a previous study, our group detected the cholecystokinin (CCK) protein in the porcine oviduct. This fact, together with the involvement of CCK in the regulation of sperm protein tyrosine phosphorylation by the modulation of HCO₃ ^- uptake (in mouse and human) suggests a role of CCK during sperm capacitation. Therefore, on the one hand, the expression of CCK receptors (CCK1R and CCK2R) on boar testes has been investigated and probed also, on the other hand, boar spermatozoa (from seminal doses of 1-day and 5-day storage) were exposed to different concentrations of CCK (0-control, 25 or 50 μM) in a medium supporting capacitation supplemented with 0, 5 or 25 mmol/L of HCO₃ ^- for 1h at 38.5 °C. Sperm motion (total and progressive motility), kinetic parameters, viability, acrosome status and mitochondrial activity were determined. No differences between groups (0, 25 or 50 μM of CCK) were observed when HCO₃ ^- was absent in the media (p> 0.05). However, the results showed that when the media was supplemented with 5 mmol/L HCO₃ ^- in 1-day seminal doses storage, linearity index (LIN, %), straightness index (STR, %) and oscillation index (WOB, %) (sperm kinetics parameters) increased in the presence of CCK regardless the concentration (p< 0.05). Nevertheless, CCK in sperm from 5-day storage only increased the WOB parameter in comparison to the control (p< 0.05). Furthermore, the average amplitude of the lateral displacement of the sperm head (ALH, μm) and curvilinear velocity (VCL, μm/s) decreased when CCK was present, depending on its concentration and sperm aging (1-day vs. 5-days) (p< 0.05). In the case of the media supporting capacitation supplemented with 25 mmol/L HCO₃ ^- , any differences were observed except for sperm viability in the 5-day seminal doses which increases in the 50 μM-CCK group compared to the control (p< 0.05). In conclusion, these data suggest an implication of CCK protein during sperm capacitation under low bicarbonate concentration increasing the sperm linear trajectory.

In vitro supplementation of testosterone or prolactin affects spermatozoa freezability in small ruminants

In small ruminants, testosterone and prolactin plasma concentrations show circannual fluctuations as an adaptation mechanism to their seasonal breeding behavior. Sperm resistance to the freezing-thawing process shows seasonal fluctuation throughout the year, with lower sperm freezability at the beginning of the breeding season when prolactin and testosterone levels reach their maximum concentration. Nevertheless, whether these hormones directly affect post-thaw sperm quality parameters is still unclear. The objective was to study the effect of testosterone or prolactin added in vitro on sperm freezability in domestic ram (Ovis aries) and buck (Capra hircus). Sperm samples were incubated for 1 h with a range of testosterone (0, 2, 4, or 6 ng/mL; Exp. 1) or prolactin (0, 20, 100, 200, or 400 ng/mL; Exp. 2) concentrations. Samples were cryopreserved by slow freezing in straws at 0 h and after 1 h incubation. Sperm viability, acrosome integrity, motility, and kinetic parameters were assessed at 0 and 1 h in fresh and frozen-thawed samples. Results showed no hormone effect in fresh sperm, whereas these hormones affected post-thaw sperm parameters. In Exp. 1, in vitro incubation with testosterone decreased the post-thaw acrosome integrity of ram sperm (from 68.1 ± 6.3% to 49.6 ± 3.9%; P < 0.05). In Exp. 2, in vitro incubation with prolactin decreased the post-thaw acrosome integrity of ram (from 78.2 ± 3.4% to 66.3 ± 3.5%; P < 0.05) and buck sperm (from 81.7 ± 2.5% to 67.6 ± 3.5%; P < 0.05). Moreover, prolactin increased the post-thaw amplitude of lateral head displacement in ram sperm (from 3.3 ± 0.1 μm to 3.8 ± 0.2 μm; P < 0.05). In conclusion, either testosterone or prolactin added in vitro decreased the post-thaw acrosome integrity of ram and buck sperm. This suggests a destabilization process that could be decreasing sperm freezability when physiological levels of these hormones are high in vivo.

Effect of temperature and cell concentration on dolphin (Tursiops truncatus) spermatozoa quality evaluated at different days of refrigeration

The use of cryopreserved dolphin spermatozoa facilitates the exchange of genetic material between aquatic parks and makes spermatozoa accessible to laboratories for studies to further our understanding of marine mammal reproduction. Sperm cryopreservation in the bottlenose dolphin (Tursiops truncatus) has been developed for the exchange of gametes within the ex situ population. The aim of this study was to develop an effective method for refrigeration of bottlenose dolphin spermatozoa diluted in a commercial extender (BTS). In Experiment 1, the effect of temperature (5 compared with 15 °C) on sperm quality was evaluated during 7 days of storage at 100 × 10⁶ spermatozoa/ml. In Experiment 2, the effect of the storage concentration (100 × 10⁶ compared with 20 × 10⁶ spermatozoa/ml) on sperm quality was assessed during 7 days of storage at 5 °C. In Experiment 1, total motility (including % of rapid sperm) was greater at 5 than 15 °C. When the effect of storage concentration was evaluated (Experiment 2), total motility and ALH were greater at the higher storage concentration (100 × 10⁶ spermatozoa/ml). For both experiments, values for viability, acrosome integrity, and normal morphology variables were consistent throughout the 7 days of refrigeration. In Experiment 3, a microbiological study was performed to evaluate the effect of the refrigeration temperature and days of storage on bacterial growth. The results of microbiological analysis indicated there was Staphylococcus aureus in some samples, however, there was no effect of temperature or days of refrigeration. In conclusion, bottlenose dolphin semen can be refrigerated for a short to medium period of storage and there is maintenance of functionality of sperm when stored at 100 × 10⁶ spermatozoa/ml at 5 °C.

Effect of boar seminal dose type (cervical compared with post-cervical insemination) on cooling curve, sperm quality and storage time

Seminal doses used for cervical and post-cervical artificial insemination (CAI and PCAI, respectively) vary in volume, the number of spermatozoa and packaging. The aim was to evaluate the outcomes when there was use of routine processing procedures for CAI- and PCAI-doses. Two different types of seminal doses were processed: 1) CAI: 2.7 × 10⁹ sperm/80 ml; 2) PCAI: 1.5 × 10⁹ sperm/45 ml. In Experiment 1, the cooling curve of seminal doses during processing occurred in two phases: 1st) At room temperature (23.4 ± 0.5 °C) from 0 (just after packaging) to 120 min; 2nd) At refrigeration (15.7 ± 0.8 °C) from 121-240 min. For the PCAI-doses, the time required to reach room temperature was 47 min compared to 107 min for CAI-doses (decreasing velocity of 0.093 °C/min and 0.048 °C/min, respectively). During refrigeration, for the PCAI-doses the time required to reach the desired preservation temperature was 20 min less than for CAI-doses (PCAI: 90 min, 0.074 °C/min; CAI: 110 min, 0.066 °C/min). In Experiment 2, sperm motility, kinetic parameters and acrosome damage for both types of doses were evaluated at 0, 24, 48 and 72 h of refrigeration. Also, morphology, pH, and osmolality were assessed at 0 and 72 h. Values for all these did not differ between CAI- and PCAI-doses. In conclusion, PCAI-doses took less time than CAI-doses to reach the desired temperature, but sperm quality was similar for CAI- and PCAI-doses during storage. Nevertheless, the different cooling curves should be taken into consideration for further investigation.

Effect of Porcine circovirus 2 (PCV-2) maternally derived antibodies on performance and PCV-2 viremia in vaccinated piglets under field conditions

Background

Nowadays, the most common presentation of PCV-2 is the subclinical infection in piglets after weaning. The success of PCV-2 vaccination is associated with the control of the clinical disease as well as the improvement of production parameters. In consequence, the objective of the present study was to analyse the effect of PCV-2 maternally derived antibody (MDA) levels on vaccine efficacy in piglets vaccinated at three weeks of age with a commercial PCV-2 subunit vaccine. The study was performed analysing a database with 6112 wean-to-slaughter piglets from 4 different European regions.

Results

Results showed that the use of the vaccine was able to decrease the PCV-2 viremia calculated as area under the curve (AUC = 60.29 ± 3.73), increase average daily weight gain (ADWG = 0.65 ± 0.01 kg/day) and reduce mortality (7%) in vaccinated piglets compared to non-vaccinated ones (AUC of 198.27 ± 6.14, 0.62 ± 0.01 kg/day and 11% respectively). The overall difference of ADWG between both groups was close to 30 g per day (p < 0.05), also when they were split for low and high levels of MDA titres. Moreover, the animals with the highest ADWG were observed in the group of piglets vaccinated with high or extremely high antibody titres (0.66 and 0.65 kg/day respectively). Considering only animals with extremely high antibody titres, both study groups performed similar, however there was a numerical difference of 10 g/day in favour of vaccinated piglets. Likewise, lack of correlation between ADWG and MDA was observed suggesting that no maternal antibody interference was present with the tested vaccine because the vaccinated animals grew faster compared to unvaccinated control animals, regardless of the level of maternal antibodies present at the time of vaccination.

Conclusions

The results of the present study demonstrated that the MDA against PCV-2 transferred through the colostrum intake has a protective effect against this viral infection. The vaccine used in the present study (Ingelvac CircoFLEX®) was effective when applied at three weeks of age and was not affected by the level of MDA at the time of vaccination.

Boar sperm with defective motility are discriminated in the backflow moments after insemination

During insemination, a large number of spermatozoa are deposited in the female genital tract, but a very low percentage is able to colonize the site of fertilization. The influx of neutrophils into the uterine lumen and semen reflux (backflow) are known mechanisms that decrease the number of spermatozoa within the uterus. No report has attempted to ascertain whether the backflow is a random or selective process of the spermatozoa. In this work, sows were inseminated using two populations of spermatozoa in the same proportion: (1) unstained spermatozoa with high motility and (2) stained spermatozoa with low, medium, or high motility. Volume, number, and percentage of stained spermatozoa were evaluated in the backflow (collected at 0-15, 16-30, and 31-60 minutes after insemination). This article provides evidence that (1) the motility characteristics of the spermatozoa do not influence the percentage of sows with backflow, the volume and number of spermatozoa in the backflow; (2) the discarding of spermatozoa in the backflow is not specific during the first moments after insemination (0-15 minutes), whereas later (16-60 minutes), spermatozoa with defective motility (low and medium groups) are discarded in a higher proportion than high group in the backflow ([16-30 minutes: low, 85.13 ± 4.32%; medium, 72.99 ± 5.05%; and high, 54.91 ± 2.38%; P < 0.0001; 31-60 minutes: low, 87.16 ± 6.01%; medium, 87.02 ± 4.01%; and high, 59.35 ± 2.86%; P = 0.001]). Spermatozoa with poor motility are discarded in the backflow probably as a selective process, on the part of the female genital tract or as a result of the intrinsic low spermatozoa motility.

196 EXPRESSION OF TISSUE-TYPE PLASMINOGEN ACTIVATOR IN OOCYTES AND CUMULUS CELLS FROM MOUSE, PIG, AND COW

Tissue-type plasminogen activator (tPA) is one of the components of the plasminogen-plasmin (PLG-PLA) system, better known as fibrinolytic system for its role in the blood clot lysis. It has been demonstrated recently that the activation of plasminogen into the protease plasmin during the sperm-oocyte interaction in the pig and cow decreases the percentages of penetration and increases monospermy (Mondéjar et al. 2012). However, in the mouse species, it was showed that PLG-PLA system enhances fertilization (Huarte et al. 1993). Expression of tPA has been described in rat oocytes (Bicsak et al. 1989) and cumulus cells (Ny et al. 1987; O’Connell et al. 1987), but no clear evidence about its expression in mouse, pig, and cow oocytes or cumulus cells is available. We hypothesised that differences in the effect of PLG-PLA system on fertilization results between the species mentioned above could be related to differences in tPA expression. The aim of this study was the detection of mRNA encoding tPA in oocytes and cumulus cells in mouse, pig, and cow by molecular analysis. Total RNA was obtained from oocytes and cumulus cells and cDNA was synthesised with an oligo-dT as primer. These cDNAs were used as template in RT-PCR amplifications using specific primers designed based on the GenBank sequence for Mus musculus, Sus scrofa, and Bos taurus tPA (NM_ 008872, NM_214054, NM_174146, respectively). The results of this study showed a different expression in the 3 studied species. In mouse, amplicon encoding tPA was detected in oocytes and cumulus cells. In cow and pig, tPA transcripts were obtained only in cumulus cells. The relation between the differences in the tPA expression pattern and the role of PLG-PLA system on fertilization remains to be investigated. This study was supported by MICINN (AGL2009-12512-C02-01-02).

Roles of the oviduct in mammalian fertilization

The oviduct or Fallopian tube is the anatomical region where every new life begins in mammalian species. After a long journey, the spermatozoa meet the oocyte in the specific site of the oviduct named ampulla and fertilization takes place. The successful fertilization depends on several biological processes that occur in the oviduct some hours before this rendezvous and affect both gametes. Estrogen and progesterone, released from the ovary, orchestrate a series of changes by genomic and nongenomic pathways in the oviductal epithelium affecting gene expression, proteome, and secretion of its cells into the fluid bathing the oviductal lumen. In addition, new regulatory molecules are being discovered playing important roles in oviductal physiology and fertilization. The present review tries to describe these processes, building a comprehensive map of the physiology of the oviduct, to better understand the importance of this organ in reproduction. With this purpose, gamete transport, sperm and oocyte changes in the oviductal environment, and other interactions between gametes and oviduct are discussed in light of recent publications in the field.

Two cases of reciprocal chromosomal translocation (4; 7)(p+; q-) (2; 8)(q-; q+) in piglets produced by ICSI

In this study, the karyotypes of 14 piglets from four different litters produced by intracytoplasmic sperm injection (ICSI) and embryo transfer were analysed. The chromosome analysis was based on a classical cytogenetic examination following the standard protocols of lymphocyte cultures. Two cases of reciprocal translocation [(4; 7)(p+; q-) and (2; 8)(q-; q+)] were detected in two female transgenic piglets. These animals showed neither anatomical nor physiological alterations and had normal growth. To our knowledge, this is the first karyotype study of piglets produced by ICSI.

301 EVALUATION OF THE SPERM-MEDIATED GENE TRANSFER (SMGT) TECHNIQUE BY IN VITRO FERTILIZATION IN PIGS USING RecA PROTEIN

Sperm-mediated gene transfer (SMGT) is a transgenesis technique used in pigs mainly byAI (Lavitrano ML et al. 2002 Proc. Natl. Acad. Sci. USA 99, 14 230–14 235), and by intracytoplasmic spermi injection (ICSI) (Garcia-Vazquez FA et al. 2006 Reprod. Domest. Anim. 41, 338), but up to now, it has not been reported by IVF (Bolling LC et al. 2003 Transgenics 4, 77–86). The aim of this study was to evaluate the efficiency of SMGT by IVF in pigs and the use of recombinase RecA to avoid possible exogenous DNA degradation by endonucleases. We designed a study with 3 experimental groups: (1) sperm incubated without exogenous DNA (control group), (2) sperm incubated with exogenous DNA (DNA group), and (3) sperm incubated with the complex RecA:DNA (RecA group). Ejaculates from mature boars were recovered and the seminal plasma was discarded to avoid detrimental effects on DNA binding. The spermatozoa were incubated with DNA or RecA-DNA and used as vectors for transferring linealized plasmid DNA [5.7 kb enhanced green fluorescent protein (EGFP)] into in vitro-matured porcine oocytes by IVF. Spermatozoa and oocytes were coincubated for 2 h in TALP medium; then, the fertilized oocytes were transferred into the culture drops with NCSU-23 medium. The binding of the DNA to the spermatozoa was confirmed by the use of enzymatic fluorescein-12-dUTP-labeled DNA and measured by flow cytometry. The total number of oocytes used was 584 (n = 59; n = 382; n = 143 for the 3 experimental groups, respectively). Embryos were examined for cleavage rate at 48 h after fertilization, and for embryo development at 144 h. Expression of EGFP in embryos was examined using a fluorescence inverted microscope. The results in our experiment showed that the coincubation of sperm with exogenous DNA induced a lower cleavage rate than when the RecA:DNA complex was used (DNA: 25.13 � 2.22 v. RecA: 41.26 � 4.13%, P < 0.05), and both no different from the control group (38.98 � 6.40). On the other hand, the production of blastocysts was similar in the 3 groups (Control: 21.74 � 8.79 v. DNA: 21.87 � 4.24 v. RecA: 15.25 � 4.72%) as well as the quality of the obtained embryos. The average number of cells per blastocyst was similar in the 3 groups (36.40 � 9.28 v. 37.26 � 3.32 v. 28.45 � 3.34, respectively). None of the produced embryos was detected for expressing protein EGFP. In conclusion, under our experimental conditions, IVF is not an effective technique for SMGT, whereas using ICSI-SMGT under the same conditions (DNA and DNA:RecA groups), we obtained a high percentage of transgenic embryos (Garcia-Vazquez FA et al. 2006 Reprod. Domest. Anim. 41, 338). Three main causes are hypothesized to be probably related to this conclusion: (i) the penetration of the oocytes is achieved only by the not DNA-bound viable spermatozoa in a competitive system, (ii) the DNA was only bound to altered membrane or dead spermatozoa, and (iii) the exogenous DNA is only present on sperm surface and in the process of fusion with oocyte membrane, the DNA is not internalized.

373 SPERM TREATMENT AFFECTS THE EFFICIENCY OF PORCINE TRANSGENIC EMBRYO PRODUCTION BY ICSI

Sperm mediated gene transfer (SMGT) is an interesting tool for animal transgenesis, consisting of the use of sperm cells as a vector for transmitting exogenous DNA into eggs at the moment of fertilization. A degradation of sperm membrane followed by incubation with DNA and fertilization using intracytoplasmic sperm injection (ICSI) proved to be efficient in mice (Perry et al. 1999 Science 284, 1180-1183; Moreira et al. 2004 Biol. Reprod. 71, 1943-1947) and rats (Kato et al. 2004 Mol. Reprod. Dev. 69, 153-158). In this study, we evaluated the effect of the sperm treatment (a quick freezing-thawing process for disrupting sperm membranes) on further transgenic expression and the embryo development of injected porcine oocytes. Ejaculated sperm cells from five fertile mature boars were used as vectors for transferring plasmid DNA (GFP: green fluorescent protein) into matured porcine in vitro oocytes by ICSI. Semen was recovered and immediately diluted 1:10 in SFM (swine fertilize medium) at 37�C and later centrifuged (800g, 10 min, 25�C), discarding the seminal plasma to avoid a detrimental effect on DNA binding to cells without further preparation (control), or after they had been subjected to membrane disruption by a quick freeze-thawing process (FT). Linealized plasmid DNA (5.4 kb) was added (1 � 108 sperm/mL + 5 mg DNA/mL) and incubated at 16�C for 30 min. 5 min before ICSI, sperm were pre-warmed at 37�C. Denuded oocytes were washed twice in DPBS medium supplemented with 10% FCS (fetal calf serum) and transferred to ICSI drops. Injected oocytes were kept in TALP medium (Rath et al. 1999 J. Anim. Sci. 77, 3346-3352) for 18 h, and then transferred to NCSU-23 medium for further embryo culture. Embryos were examined for cleavage rate at 48 h following injection, and for embryo development at 144 h. GFP expression in embryos was examined under fluorescent light using a fluorescence inverted microscope. In this preliminary study, 105 and 101 oocytes were injected for control and FT groups, respectively. The cleavage rate was similar between groups (control: 49/105 (46.7%) vs. FT: 39/101 (38.6%); P = 0.25). However, the blastocyst formation rate was lower in the FT than in control group (control: 13/105 (12.4%) vs. FT: 4/101 (4.0%); P = 0.03). In relation to transgenic expression, the FT group showed a significantly higher number of transgenic embryos (control: 50.98 % vs. FT: 75.51%; P = 0.01). These results confirmed that treatment of the sperm prior to the ICSI could affect the efficiency of the production of transgenic embryos. The disruption of sperm membrane increases the DNA binding and the possibilities of carrying the DNA into the oocyte, and freezing-thawing technique is simple and effective to achieve this purpose. However, the freezing process could damage the sperm nucleus structure and decrease the viability of the embryo produced. Nevertheless, the efficiency of the transgenesis expression was very high (more than 75% of the embryos were obtained), and it should be a useful tool to produce transgenic pigs. This work was supported by AGL2003-03144.