Nanotechnology in reproduction: Vitamin E nanoemulsions for reducing oxidative stress in sperm cells

Vitamin E is considered a powerful biological antioxidant; however, its characteristics such as high hydrophobicity and low stability limit its application. We propose to use nanotechnology as an innovative tool in spermatology, formulating nanoemulsions (NE) that accommodate vitamin E, protecting it from oxidation and promoting its release into the medium. The protective effect of the NE against oxidative stress was assessed in red deer epididymal sperm incubated at 37 °C. Cryopreserved sperm from eleven stags were thawed and extended to 400 × 10⁶ sperm/ml in Bovine Gamete Medium (BGM). Once aliquoted, the samples were supplemented with the NE at different concentrations (0, 6 and 12 mM), with or without induced oxidative stress (100 μM Fe²⁺/ascorbate). The samples were evaluated after 0, 2 and 4 h of incubation at 37 °C. Motility (CASA), viability, mitochondrial membrane potential, acrosomal status, lipoperoxidation (C11 BODIPY 581/591), intracellular reactive oxygen species (ROS) production and DNA status (SCSA®) were assessed. After 2 and 4 h of incubation, the NE were able to prevent the deleterious effects of oxidative stress, thus improving total and progression motility (P ˂0.05). Moreover, the highest concentration tested (12 mM) improved almost every sperm kinematic variable (P ˂0.05) and preserved sperm viability in samples subjected to oxidative stress. In addition, 12 mM of NE protected the acrosomes integrity, maintained and protected mitochondrial activity, prevented sperm lipoperoxidation and reduced ROS production (P ˂0.05) in samples subjected to oxidative stress. This work indicates for the first time that vitamin E formulated in NE could be a new approach against sperm oxidative damage. This could be highly relevant for sperm physiology preservation in the context of assisted reproduction techniques.

Cinnamtannin B-1, a novel antioxidant for sperm in red deer

Cinnamtannin B-1 (CNB-1) is a naturally occurring trimeric A-type proanthocyanidin contained in several plants such as cinnamon (Cinnamomum zeylanicum). It is considered to be a potent antioxidant. The protective effect of CNB-1 against oxidative stress was assessed in red deer epididymal sperm incubated at 37 °C. Cryopreserved sperm from six stags were thawed, pooled and extended to 400 × 10⁶ sperm/ml in BGM (bovine gamete medium). After being aliquoted, the samples were supplemented with different concentrations of CNB-1 (0, 0.1, 1, 10 and 100 μg/mL), with or without induced oxidative stress (100 μM Fe²⁺/ascorbate). The samples were evaluated after 0, 2 and 4 h of incubation at 37 °C. This experiment was replicated six times. Spermmotility (CASA), viability, mitochondrial membrane potential, acrosomal status, lipoperoxidation (C11 BODIPY 581/591), intracellular reactive oxygen species (ROS) production and DNA status (TUNEL) were assessed. After 4 h of incubation, CNB-1 prevented the deleterious effects of oxidative stress, thus improved sperm progressivity and velocity (P<0.05). Furthermore, 1 and 10 μM CNB-1 improved sperm linearity, even when compared to those samples that had not been subjected to oxidative stress (P<0.05). The greatest concentration, 100 μM, prevented sperm lipoperoxidation and reduced ROS production in samples subjected to oxidative stress.

Objective evaluation of ram and buck sperm motility by using a novel sperm tracker software

This work offers researchers the first version of an open-source sperm tracker software (Sperm Motility Tracker, V1.0) containing a novel suit of algorithms to analyze sperm motility using ram and buck sperm as models. The computer-assisted semen analysis is used in several publications with increasing trend worldwide in the last years, showing the importance of objective methodologies to evaluate semen quality. However, commercial systems are costly and versatility is constrained. In the proposed method, segmentation is applied and the tracking stage is performed by using individual Kalman filters and a simplified occlusion handling method. The tracking performance in terms of precision (number of true tracks), the percentage of fragmented paths and percentage of correctly detected particles were manually validated by three experts and compared with the performance of a commercial motility analyzer (Microptic's SCA). The precision obtained with our sperm motility tracker was higher than the one obtained with a commercial software at the current acquisition frame rate of 25 fps (P < 0.0001), concomitantly with a similar percentage of fragmentized tracks (P = 0.0709) at sperm concentrations ranging 25-37 × 10⁶ cells/mL. Moreover, our tracker was able to detect trajectories that were unseen by SCA. Kinetic values obtained by using both methods were contrasted. The higher values found were explained based on the better performance of our sperm tracker to report speed parameters for very fast motile sperm. To standardize results, acquisition conditions are suggested. This open-source sperm tracker software has a good plasticity allowing researchers to upgrade according requirements and to apply the tool for sperm from a variety of species.

144 Dynamic of Sperm Subpopulations in Red Deer Capacitated Samples

An ejaculate is a mixture of sperm subpopulations (SP) with varying motility characteristics. Moreover, males with high percentages of fast and linear-moving sperm have high rates of fertility (Ramón et al. 2003 Biol. Reprod. 89, 110). The objective was to assess dynamics, over time, of SP of capacitated red deer sperm. Thawed sperm were selected with 45/90% Percoll, diluted at 10 × 106 sperm mL−1 in SOF plus 10% oestrous sheep serum and incubated for 2 h at 38.5°C under 5% CO2. Sperm motility was assessed by computer-assisted semen analysis at 1, 5, 15, 30, 45, 60, and 120 min and 24 h. Sperm were classified as described previously (Martínez-Pastor et al. 2005 Biol. Reprod. 72, 316-327) and the evolution of SP during capacitation was characterised with piece-wise regression that identified change points. Five sperm SP were identified based on velocity according to an actual path (VCL), velocity according to a straight path (VSL), velocity according to the average, smoothed path (VAP), linearity (LIN), straightness (STR), wobble (WOB), amplitude of lateral displacement of sperm head (ALH), and frequency of the flagellar beat (BCF). Sperm in SP1 were fast, linear sperm with high ALH; they corresponded to capacitated sperm. In contrast, SP5 were slow, non-linear sperm, with low ALH (Table 1). The dynamics of each SP differed over time was different along the time. Percentages of SP1, SP4, and SP3 were significantly decreased at 60, 90, and 100 min, whereas percentages of SP2 and SP5 did not change over time. This study was consistent with previous reports that kinematic sperm characteristics change over time. Table 1.Sperm subpopulations (SP) based on kinematic end points.

Immature and mature sperm morphometry in fresh and frozen-thawed falcon ejaculates

Sperm morphometry is one characteristic which may be useful in prediction of fertility and sperm freezability in a species. Knowledge of the sperm characteristics of the ejaculate and the morphometric descriptors is necessary to effectively develop sperm cryopreservation. The aim of the current study was to provide a general description of the sperm from two falcon species (Peregrine falcon Falco peregrinus peregrinus/brookei and Gyrfalcon Falco rusticolus) including immature sperm, sperm head morphometric descriptors, and the existence of mature sperm subpopulations. Semen samples were collected by massage and voluntary false copulation and diluted with Lake and Ravie medium. Smears were prepared of the diluted samples, stained with Hemacolor^®, and subjected to: 1) morphological analysis (bright field optical microscopy), and 2) computerised morphometric analysis; each sperm head was measured for length, width, area and perimeter. In addition, in the Gyrfalcon, pooled semen was frozen in pellets using DMA as a cryoprotectant and the analyses repeated after thawing. The mean percentage of immature sperm (spermatocytes and spermatids) was similarly high in all species/subspecies: Brookei Peregrine falcon (F. p. brookei) 55.5%, European Peregrine falcon (F. p. peregrinus) 65.5% and Gyrfalcon 64.7%. Clustering analyses identified four subpopulations of mature spermatozoa with different morphometric characteristics (P < 0.001). The relative proportions of these subpopulations were similar in all three species. The mean values recorded for the morphometric variables of the four subpopulations were, however, lower (P < 0.001) in the thawed Gyrfalcon samples than in fresh samples. The results support the idea of pleiomorphy as a characteristic of raptor mature sperm. This finding, plus that of the existence of four sperm subpopulations with different morphometric characteristics, may be important in the future development of cryopreservation protocols for falcon sperm.

Effect of sex-sorting and cryopreservation on the post-thaw sperm quality of Iberian red deer spermatozoa

This study investigated the effect of sex-sorting and cryopreservation on post-thaw characteristics and fertility of red deer (Cervus elaphus) sperm for the first time. Semen was collected by electroejaculation from 10 mature stags during the breeding season, and each ejaculate split into four experimental groups: Bulk sorted spermatozoa, sorted but not sexed (BSS); sorted high purity X-spermatozoa (XSS); sorted high purity Y-spermatozoa (YSS); and, control non-sorted spermatozoa (NS). Following, all samples were frozen over liquid nitrogen. Two straws per stag and sample type were analyzed immediately post-thaw and following a 2-h incubation period at 37 °C. Post-thaw total motility (TM) as assessed by CASA was not different (P < 0.05) among NS, BSS and YSS sperm. For XSS, post-thaw TM was lower (39%, P < 0.05) than that for NS (54%) or BSS (50%), but similar (P > 0.05) to that of YSS (47%) sperm. The percentage of apoptotic spermatozoa as assessed by PI/YO-PRO-1 and flow cytometry analysis, was higher (17%, P ≤ 0.05) for XSS sperm than NS (12%), BSS (13%) and YSS (14%) sperm. Following incubation there were no differences (P > 0.05) in TM or percent apoptosis among treatments. Post-thaw chromatin stability calculated as the DNA fragmentation index (%DFI) was similar among treatments; following incubation %DFI increased in all except YSS, which displayed the lowest value (P < 0.05). Artificial insemination of synchronized hinds yielded 44, 52 and 62% delivery rates for YSS, NS and standard frozen-thawed sperm, respectively (P < 0.05). Notably, 93 and 55% of fawns born were males for the YSS and NS spermatozoa, respectively (P < 0.05). In summary, Y-sorted sperm displayed acceptable post-thaw sperm evaluation parameters and the expected offspring sex ratio. More studies are needed to understand the source of sperm damage that may compromise the fertility of Y-sorted red deer sperm.

Selection of red deer spermatozoa with different cryoresistance using density gradients

The objective of sperm selection media is selecting the best spermatozoa and to remove seminal plasma and diluent for using them in assisted reproductive techniques. It is known that individuals show different cryoresistance in response to the same freezing procedure. Our hypothesis was that the efficacy of selection media could be dissimilar for samples with different sperm quality after thawing. Epididymal sperm samples from mature Iberian red deer were collected and frozen. Males were classified as with high post-thaw sperm quality when sperm motility (SM) ≥ 70%, or as with low post-thaw sperm quality when SM ≤ 69%. Samples were centrifuged using the following density gradients (DG): Percoll^® , Puresperm^® and Bovipure^™ , and several functional sperm parameters were assessed after sperm selecting and washing. Males classified with high sperm quality had higher post-thawing values (p > .05) for all parameters evaluated, except for linearity index, than those categorized as low sperm quality. After selection, some sperm characteristics improved (viability, apoptosis and mitochondrial activity) for both groups, showing the males with high sperm quality higher values in all sperm parameters except for kinematic traits and DNA fragmentation index (%DFI), regardless of DG. Bovipure^™ yield lower values of sperm motility, viability, apoptosis and mitochondrial activity in relation to Percoll^® and Puresperm^® considering both quality groups. There was an interaction between the type of DG and sperm quality group for sperm viability (p = .040) and apoptosis (p = .003). Thus, Percoll^® selected less live and more apoptotic spermatozoa than Puresperm^® and Bovipure^™ for males with low sperm quality. In conclusion, the DG are more efficient selecting spermatozoa from samples with high sperm quality, acting differently depending on initial sperm quality.

The Effect of Oxidative Stress on Thawed Bulk-Sorted Red Deer Sperm

The aims of this study were to assess the effects of the sex-sorting process on post-thaw sperm quality as well as on induced oxidative stress damage (H2 O2 0 mm = H000; H2 O2 50 mm = H050; H2 O2 100 mm = H100) and the protective action of reduced glutathione (GSH) and Trolox, when comparing sorted (BSS) and non-sorted (NS) red deer spermatozoa incubated at 37°C. Sperm samples from three stags were collected by electroejaculation and frozen. Immediately after thawing, sperm motility was higher (p < 0.05) for NS (59% ± 3.3) than BSS (36.9% ± 5.8) sperm. Furthermore, the percentage of apoptotic sperm was higher (p < 0.05) for BSS (21.6% ± 5.0) than NS sperm (14.6% ± 1.2). The presence of H2 O2 increased DNA damage in NS (H000 = 4.1% ± 0.9; H050 = 9.3% ± 0.7; and H100 = 10.9% ± 2.3), but not in BSS sperm. However, in the presence of oxidant, GSH addition improved (p < 0.05) sperm motility in both groups of sperm samples as compared to their controls (NS: 44.5 ± 4.8 vs 21.1 ± 3.9 and BSS: 33.3 ± 8.1 vs 8.9 ± 1.8). These results demonstrate that the sperm-sorting process induces sublethal effects, albeit selecting a sperm population with a chromatin more resistant to oxidative stress than that in non-sorted sperm. Moreover, addition of GSH at 1 mm may be a good choice for maintaining the quality of stressed sperm samples, unlike Trolox, which inhibited sperm motility.

Reduced glutathione addition improves both the kinematics and physiological quality of post-thawed red deer sperm

The potential protective effect of reduced glutathione (GSH) and trolox (TRX), an analogue of vitamin E, supplementation during in vitro culture (2h, 39°C) of electroejaculated frozen/thawed red deer sperm was investigated. Cryopreserved sperm were thawed and incubated with no additive (Control) and 1mM or 5mM of each antioxidant to find out whether these supplementations can maintain the sperm quality, considering the use of thawed samples for in vitro techniques such as in vitro fertilisation (IVF), sperm sex sorting or refreezing. The effect of GSH on sperm motility was positive compared to TRX which was negative (P<0.001). After 2h of incubation at 39°C, use of GSH improved motility while TRX supplementation reduced sperm motility compared with Control samples without antioxidant. Use of TRX at both concentrations (1 and 5mM; TRX1 and TRX5) resulted in lesser percentages of apoptotic sperm (12.4±1.1% and 11.7±0.9%) than GSH1, GSH5 (15.2±1% and 14.6±1.1%) and Control samples (16.9±1.2%) (P<0.001). Use of GSH at both concentrations (1 and 5mM) resulted in greater mitochondrial activity as compared with findings for the Control, TRX1 and TRX5 groups. Results of this study indicate that GSH is a suitable supplement for electroejaculated red deer sperm. It would be necessary to conduct fertility trials (in vivo and in vitro), to assess whether GSH supplementation of thawed red deer sperm could improve fertility rates.

What does testosterone do for red deer males?

Testosterone has been proposed to have a dual effect, enhancing sexual traits while depressing parasite resistance in males. Here, we test this hypothesis in red deer, examining males from captive populations during the whole annual cycle and males from natural populations during the breeding season. We first explored the effects of body size, age and sampling date on testosterone to avoid confounding effects. Our results show that in captive populations seasonal changes in testosterone levels were mirrored by changes in testes size, and that during the rut there was a strong correlation between both. In natural populations, males with higher testosterone levels had larger testes, improved sperm quality, smaller burr diameter, stronger antlers, higher haematocrit levels, and increased nematode parasite load. By contrast, no significant relationship was found between testosterone and spleen size or tick parasite load. We conclude that testosterone (i) improves males' reproductive investment and physical stamina, (ii) improves antler strength but reduces burr diameter, and (iii) imposes a cost in terms of depressed parasite resistance.

Cryopreservation of Iberian red deer (Cervus elaphus hispanicus) spermatozoa obtained by electroejaculation

We tested extenders and freezing protocols for Iberian red deer semen. Samples were obtained by electroejaculation (10 stags), and analyzed for motility (CASA), viability (propidium ioide), acrosomal (PNA-FITC) and mitochondrial status (JC-1). Samples were diluted 1+1 in extender, cooled and adjusted for glycerol (extender with higher glycerol concentration), brought to 160 x 10(6)mL(-1) and frozen. Four experiments were carried out, repeating sperm analysis after thawing to compare treatments. In a first experiment, seven samples were frozen using Triladyl (20% egg yolk) and UL extender (Tes-Tris-fructose, 15% egg yolk, 4% glycerol). Triladyl yielded higher motility after thawing. In a second trial, 17 samples were frozen using Triladyl, Andromed, Bioxcell, and UL with 8% LDL (low-density lipoproteins). Triladyl, and Andromed performed better than Bioxcell on motility, and than UL-LDL on viability and acrosomal status. In a third experiment, the performance of freezing the sperm-rich ejaculate fraction versus the whole ejaculate was tested on nine samples. The sperm-rich ejaculate fraction not only rendered more motile and viable spermatozoa but also showed higher freezability (higher motile spermatozoa recovery). In a fourth experiment, we tried three modifications of the freezing protocol, for improving the freezability of low concentration samples: prior removal of seminal plasma; replacing extender (second fraction) for pure glycerol to reduce dilution; and performing only the 1+1 dilution, not the second dilution. No differences were found, although only three samples could be used. Both Triladyl and Andromed were deemed appropriate for freezing Iberian red deer semen, and the rich fraction should be selected for freezing.

159 WASHING INCREASES THE VULNERABILITY OF RED DEER THAWED SPERMATOZOA TO OXIDATIVE STRESS

This study is an attempt to increase our knowledge on the effect that sperm preparation techniques have on thawed spermatozoa from wild ruminants. Semen banks for wild species can be maintained and used for artificial insemination and IVF, but it is necessary to optimize spermwork. Our objective was to assess the effect of centrifugation, dilution and oxidative stress on viability of cryopreserved sperm in the Iberian red deer (Cervus elaphus hispanicus), considering the hypothesis that washing increases the susceptibility of red deer thawed spermatozoa to oxidative stress. We used epididymal samples (200 × 106 sperm mL–1) from four Iberian red deers, stored in our wildlife cryobank. One straw per male was thawed and diluted to 30 × 106 mL–1 with BGM (Hepes-based) medium, and processed in a 2 × 4 factorial design as follows. Half of each diluted sample was centrifuged (300g, 5 min), and the pellet resuspended with fresh BGM at the same concentration. The diluted and washed samples were divided again, adding: nothing (Control), 1 mm Trolox (vitamin E), 0.1 mm Fe2+/0.5 mm ascorbate (oxidant), or Trolox plus oxidant. Tubes were incubated at 37°C and analyzed each hour for 3 h. Membrane (YO-PRO-1: apoptotic, merocyanine 540: stability, PI: damaged) and mitochondrial status were assessed simultaneously using YO-PRO-1/Merocyanine 540/propidium iodide/Mitotracker Deep Red staining (Invitrogen) evaluated with flow cytometry. Linear mixed-effects models were used to test incubation, additives and dilution/washing effects. The proportion of viable and non-apoptotic spermatozoa decreased with time (40% ± 1 at 0 h to 23% ± 1 at 3 h; P < 0.001). However, there were no significant differences among treatments. Merocyanine-negative spermatozoa decreased slightly with time in the diluted samples (97% ± 0.3 to 87% ± 3 at 3 h; P < 0.05), but no differences were found among treatments. However, the proportion of spermatozoa with active mitochondria (in the viable and non-apoptotic population) decreased dramatically when samples were washed and only oxidant was added (84% ± 5 to 5% ± 3 at 3 h; P < 0.001), while this parameter of the remaining treatments gradually decreased (86% ± 2 to 78% ± 1 at 3 h). These results support the hypothesis that washing increases the susceptibility of red deer thawed spermatozoa to oxidative stress. Nevertheless, in the absence of oxidative stress, gentle centrifugation had no additional detrimental effect over that of direct dilution. Moreover, the antioxidant, Trolox, abolished the negative effect of the oxidant on loss of mitochondrial activity. Although we did not observe an improvement in the absence of oxidant, it is possible that antioxidants may have a positive effect in the long term. This should be explored in future studies. Supported by grants AGL2004-05904/GAN (MICINN) and PAC06-0047 (JCCM). F. Martínez-Pastor, M.R. Fernández-Santos and M. Esteso were supported by the Juan de la Cierva program (MICINN).

Extender osmolality and sugar supplementation exert a complex effect on the cryopreservation of Iberian red deer (Cervus elaphus hispanicus) epididymal spermatozoa

We have carried out two experiments to study the cryobiology of red deer epididymal spermatozoa and to improve freezing extenders: (1) effect of extender (Tris-citrate-fructose) osmolality (300-600 mOsm/kg), and (2) effect of sugar (0.4M) supplementation to the extender (no sugar, glucose, fructose, mannose, sucrose, maltose, threalose and raffinose). Sperm quality was assessed pre-freezing, post-thawing, and after 2h at 37 degrees C post-thawing: sperm motility index (SMI), acrosome integrity and membrane integrity (HOS test) were assessed subjectively; mitochondrial activity (JC-1) and membrane stability (merocyanine 540) were assessed by flow cytometry. In experiment 2, DNA status was assessed using acridine orange and flow cytometry. To find an optimal osmolality, we fitted the data to a quadratic curve. Four hundred Osmolal per kilogram rendered better results pre-freezing and post-thawing. However, post-thawing viability and most parameters after 2h incubation fitted a linear model. Osmolalities above 425 mOsm/kg were deleterious (P<0.05). In experiment 2, fructose had a positive effect respect to control after 2h of incubation at 37 degrees C post-thawing. Di and trisaccharides were deleterious. Trehalose showed impaired DNA status after 2h incubation. In conclusion, the osmolality of the extenders should be around 400 mOsm/kg, although the change from quadratic to lineal may indicate a complex effect that must be further studied. Monosaccharides may enhance red deer epididymal sperm cryopreservation, especially fructose, whereas di and trisaccharides may not be adequate.

115 RELATIONSHIP BETWEEN IN VIVO FERTILITY OF MANCHEGA EWES LAPAROSCOPICALLY INSEMINATED WITH FROZEN - THAWED RAM SEMEN AND HETEROLOGOUS CALF IN VITRO FERTILIZATION

Cryopreservation may damage the fertilizing ability of spermatozoa. For this reason, it is important to assess the sperm before artificial insemination. In vitro fertilization (IVF) tests are the most suitable for assessing overall sperm function during fertilization. The aim of this work was to study whether a relationship exists between heterologous calf in vitro fertilization and in vivo fertility in Manchega sheep, with the purpose of predicting in vivo fertility of males before using their semen. Frozen–thawed sperm from 4 Manchega rams was used to laparoscopically inseminate 481 ewes of the same breed. Sperm was cryopreserved in a TRIS-yolk-glycerol extender. A minimum of 10 females were laparoscopicly inseminated per ram. These same straws were used for IVF (4 replicates per male). Domestic calf ovaries were collected at a slaughterhouse. Inmature cumulus–oocyte complexes (COCs) were aspirated and matured in vitro in TCM-199 with 10 ng mL-1 EGF and 100 �M cysteamine. After 24 h, zona-intact mature oocytes were incubated in synthetic oviduct fluid supplemented with 10% estrous sheep serum. Thawed spermatozoa were co-incubated with the oocytes (one million per well) for 40 h, and the cleavage rate was asessed. A regresion analysis was performed. The in vivo fertility ranged from 25.00 to 62.50%. Two rams had a fertility under 30.00% and the other ones over 55.00%. The in vitro fertility ranged from 42.50 to 58.50%. The in vivo fertility was not related to the in vitro fertility (P = 0.17). This could be due to the low number of males used in this work. Heterologous calf in vitro fertilization tests cannot be used to predict in vivo fertility of ram semen since no relationship was found between both variables. Nevertheless, these results are preliminary and we are working with more rams and replicates to obtain more information. This work was funded by INIA and Consejeria de Agricultura de Castilla-La Mancha. Garcia-Alvarez enjoyed a studentship from the INIA

Cryopreservation of Iberian red deer (Cervus elaphus hispanicus) epididymal spermatozoa: Effects of egg yolk, glycerol and cooling rate

Two experiments were conducted to determine the effects of egg yolk (EY), glycerol, and cooling rate on the cryosurvival of red deer epididymal spermatozoa. The aim of Experiment 1 was to examine the effects of two EY types (clarified EY, CE, prepared by centrifugation, and whole EY, WE), and four EY concentrations (0, 5, 10 and 20%) on cryosurvival of red deer epididymal spermatozoa. Sperm samples were diluted to a final sperm concentration of approximately 200 x 10(6)spermatozoa/ml with a Tris-citrate-fructose-EY extender (TCF) prior to freezing. Sperm cryosurvival was judged in vitro by microscopic assessments of individual sperm motility, viability and of plasma membrane (by means of the HOS test) and acrosome (NAR) integrities. Cryopreservation of red deer epididymal spermatozoa frozen in a clarified EY extender, and with a 20% EY resulted in more vigorous post-thaw and post-incubation motilities (P<0.0001). Moreover, our results showed that regardless of the egg yolk concentration tested, the best sperm quality was obtained with the use of CE. Therefore, the objective of Experiment 2 was to explore the post-thaw effects of four clarified egg yolk concentrations (0, 5, 10 and 20%), two final glycerol concentrations (3 and 6%), and two cooling rates from 22 to 5 degrees C (slow: 0.23 degrees C/min; rapid: 4.2 degrees C/min) on red deer epididymal spermatozoa. At thawing, the effects of CE and glycerol concentrations, and cooling rate, all independently affected post-thaw sperm quality, while there were no effects of interactions on post-thawing sperm quality. Therefore, we studied each variable separately. Differences (P<0.05) for most of the semen parameters evaluated were found between the two final glycerol concentrations tested, with the high values after thawing found with the use of 6% glycerol (58.8+/-1.4 versus 46.2+/-1.4, for sperm motility). Moreover, the cooling rate did not have an effect on the semen characteristics, except for NAR (P<0.05), with the high values after thawing found with the use of the rapid protocol (64.5+/-1.4 versus 59.9+/-1.4). In conclusion, the use of 20% CE and 6% glycerol in combination with a rapid cooling rate, significantly improved red deer epididymal spermatozoa freezability.

Inbreeding and Reproduction in Endangered Ungulates: Preservation of Genetic Variation through the Organization of Genetic Resource Banks

There is a constant increase in the number of species suffering marked reductions in population size. This reduction in size and the lack of genetic flow may lead to a decrease in genetic variability and to matings between close relatives (i.e. inbreeding) with an ensuing reduction in fitness. It is thus important to understand the mechanism underlying the deleterious effects of inbreeding and to develop reproductive biotechnologies that will allow the reduction of inbreeding depression by facilitating gene exchange between populations. The study of three endangered species of gazelles, Cuvier's gazelle (Gazella cuvieri), Mohor gazelle (Gazella dama mhorr) and dorcas gazelle (Gazella dorcas neglecta) has revealed that inbreeding negatively affects several semen parameters (motility, sperm morphology, acrosome integrity). Semen cryopreservation has been achieved in the three species but success varies depending on the diluent employed and the level of inbreeding. Artificial insemination of Mohor gazelles have led to the birth of the first gazelle born using frozen-thawed semen but improvements are needed before this technology can be applied on a routine basis for the genetic management of the populations. Collection of oocytes after ovarian stimulation, followed by in vitro maturation, fertilization and culture has met with some initial success in the Mohor gazelle. These, together with other reproductive technologies, will offer an invaluable help in preserving the maximum of genetic diversity of these and related endangered ungulate species.

The Application of Reproductive Technologies to Natural Populations of Red Deer

Over the past decade, there has been increasing interest in the application of reproductive technology to the conservation and management of natural populations of deer. The application of assisted reproduction technologies within natural population of deer is in its infancy. However, its future potential is enormous, particularly in relation to genetic management or conservation. This paper reviews the present state of such technologies for a wild subspecies of red deer, the Iberian red deer (Cervus elaphus hispanicus), by discussing the major components of oestrous synchronization, semen collection/cryopreservation and insemination techniques. In addition, findings made during the course of studies on natural populations have enormous potential for the understanding of novel reproductive mechanism that may not be uncovered by livestock or human studies. A summary of these results are also reviewed here.

The effects of cryopreservation on the morphometric dimensions of Iberian red deer (Cervus elaphus hispanicus) epididymal sperm heads

Computer-automated sperm-head morphometry was used in this study to determine the effects of cryopreservation on red deer sperm-head morphometry. Epididymal sperm samples were collected from 40 mature stags and were divided. One portion was diluted at room temperature in a Tris-citrate egg yolk medium, containing 6% glycerol. A microscope slide was prepared from single extended sperm samples prior to freezing. The remainder of each sample was frozen in nitrogen vapours. After thawing, sperm smears were prepared as described above. All slides were air dried and stained with Hemacolor. The sperm-head dimensions for length, width, area, perimeter and shape factor (length/width), for a minimum of 135 spermatozoa were determined for each slide by means of the Sperm-Class Analyser (SCA). Firstly, our results show that cryopreservation substantially reduced (p < 0.001) sperm motility and plasma membrane and acrosome integrities. In addition, sperm heads were significantly smaller in cryopreserved spermatozoa than in the companion extended samples for area (32.05 microm2 vs 32.56 microm2; p < 0.05), length (8.46 microm vs 8.53 microm; p < 0.0001) and shape factor (1.833 vs 1.849; p < 0.0001) for all stags. These differences were found within 29 of 40 stags (75%) for at least three of the morphometric parameters. The individual variability (CV) of sperm head measurements from extended samples was negatively correlated (p < 0.005) with the per cent of change in sperm head measurements after cryopreservation for area (r = -0.465), width (r = -0.483) and perimeter (r = -0.375). Thus, the lower the sperm head variability in the extended samples, the greater the sperm change as a consequence of the cryopreservation. These results suggest that the variability (heterogeneity) in sperm head dimensions of individual stags may be a good indicator of sperm freezability.

Effects of Egg Yolk and Cooling Rate on the Survival of Refrigerated Red Deer (Cervus elaphus hispanicus) Epididymal Spermatozoa

Egg yolk is a common component to sperm refrigeration for most of the deer species, the role of which is to protect sperm membranes against cold shock. In addition, there have been many studies of conservation of ejaculated semen from stags, but few have been reported for epididymal spermatozoa. This work was designed to investigate the combined effects of cooling rates (slow: 0.23 degrees C/min vs rapid: 4.2 degrees C/min) from room temperature to 5 degrees C, and egg-yolk concentration (0, 5 or 20%) in the extender on the survival of Iberian red deer epididymal spermatozoa refrigerated at 5 degrees C. Heterospermic sperm samples were diluted to a final sperm concentration approximately 400x10(6) sperm/ml with a Tris-citrate-fructose (TCF)-egg-yolk diluent. Sperm quality was in vitro judged by microscopic assessments of individual sperm motility [sperm motility index (SMI)], and of plasma membrane (hypo-osmotic swelling test) and acrosome (NAR) integrities. Our results first showed that the presence of egg yolk in the extender significantly improves (p=0.01) the viability and sperm motility after sperm dilution. In addition, acrosome and plasma membrane integrities post-refrigeration did not differ significantly between cooling procedures; however, the SMI differed significantly between cooling procedures (slow: 46.6% vs rapid: 50.0%; p=0.01). Our results also showed that sperm quality was significantly (p<0.01) affected by the combined effects of egg-yolk concentration and cooling procedure, being rapid cooling with 20% of egg yolk the most suitable combination for epididymal sperm refrigeration. In conclusion, egg-yolk improved red deer epididymal spermatozoa characteristics after dilution. Rapid cooling protocol using TCF with 20% egg-yolk significantly improved sperm motility of red deer epididymal spermatozoa after cooling.

Characteristics of Iberian red deer (Cervus elaphus hispanicus) spermatozoa cryopreserved after storage at 5°C in the epididymis for several days

The aim of this study was to assess the influence of prolonged cold storage of Iberian red deer epididymides on post-thaw sperm characteristics. Thirty-seven pairs of testes, with attached epididymides, were collected during November and December. Spermatozoa from one of each of the pairs were immediately recovered, evaluated and frozen (control group). The remaining epididymides were cooled to 5 degrees C and stored for 12, 24, 48, 72 and 96 h (experimental groups), after which spermatozoa were collected and frozen as in the control group. After thawing, sperm motility, membrane and acrosome integrities, mitochondrial function and DNA damage were evaluated. The motility of spermatozoa stored in the epididymis for up to 96 h did not decrease significantly (P>0.05) but, after cryopreservation, a decline in sperm motility was seen in spermatozoa stored for 48 h, or later. A slower decrease in sperm membrane and acrosome integrities after cryopreservation were seen as storage time progressed. Some differences were seen when different methods were used to assess the same sperm parameter although changes followed similar patterns. This was the case for acrosome integrity (phase contrast microscopy versus fluorescent lectin) or membrane integrity (hypo-osmotic swelling test or nigrosin-eosin stain versus propidium iodide). We conclude that frozen-thawed spermatozoa of Iberian red deer recovered from epididymides stored at 5 degrees C have a good sperm quality (including motility) during less than 48 h of storage for most of the sperm parameters assessed.

Comparison of three different staining methods for the assessment of epididymal red deer sperm morphometry by computerized analysis with ISAS

When collection of ejaculated sperm samples is not possible, as is the case with wild species, the epididymides of sacrificed wild males become the only possible source of spermatozoa. Mature cauda epididymal spermatozoa display characteristics similar to those of ejaculated sperm cells. The present work proposes a sperm staining technique suitable for the morphometric evaluation of red deer epididymal sperm using a new computerized system. Epididymides from wild animals were extracted no later than 2h post mortem. After epididymal sectioning, sperm samples were collected, cooled to and equilibrated at 5 degrees C, and frozen in liquid nitrogen. Before staining, sperm samples were thawed for 20s at 37 degrees C, and used for the preparation of slides. Three different sperm stains were tested: Hemacolor, Diff-Quik, and Harris' Hematoxylin. Morphometric analyses of sperm samples were performed using the morphologic module of the ISAS. Two hundred spermatozoa per sample and stain were captured at random and analyzed. Sperm morphometric values were significantly affected by the staining technique used. Moreover, significant differences were observed between animals. In our study, Diff-Quik could be considered to be the best sperm staining method, as it provided the highest percentage of well automatically analyzed cells by the ISAS, and discriminates better between animals. This sperm staining technique also proved to be a useful method for characterizing and discriminating between sperm samples of different animals.

Sperm cryopreservation in three species of endangered gazelles (Gazella cuvieri, G. dama mhorr, and G. dorcas neglecta)

Long-term storage of semen by cryopreservation, with high recovery rates on thawing, is essential for the establishment of genetic resource banks of endangered species. The purpose of the present study was to evaluate various diluents for the cryopreservation of spermatozoa from three species of gazelles (genus Gazella) in a captive breeding program. The diluents compared were Tes (N-tris(hydroxymethyl)methyl-2 aminoethane sulfonic acid)-Tris with 5% egg yolk and 6% glycerol (TEST) and Triladyl, yolk-citrate, Tris-trehalose, and Tris-lactose-all of them with 20% egg yolk and 6% (Triladyl) or 8% glycerol. Semen was obtained by electroejaculation from 12 G. cuvieri, 12 G. dama, and 13 G. dorcas males. Samples with less than 50% motile sperm, positive endosmosis, or acrosome integrity were not used. Diluted samples were loaded into 0.25-ml straws, cooled slowly to 5 degrees C over 1.5 h (-0.16 degrees C/min), equilibrated at that temperature for 2 h, frozen in nitrogen vapors for 10 min, and plunged into liquid nitrogen. Subsamples were assessed fresh, after refrigeration-equilibration, after freezing and thawing, and 2 h after thawing. Differences were seen between diluents, with best overall recovery rates after freezing and thawing found with Triladyl, TEST, and Tris-trehalose in G. cuvieri, TEST in G. dama, and Triladyl and TEST in G. dorcas. Differences were observed between species in the ability to withstand freezing and thawing, with best results seen in G. dorcas, intermediate results in G. dama, and worst results in G. cuvieri. These differences were inversely related to the average values of inbreeding of these populations. The underlying mechanism responsible for these differences may be a differential resistance to osmotic shock.