Hoechst 33342 stain and u.v. laser exposure do not induce genotoxic effects in flow-sorted boar spermatozoa

Establishment of methods to analyze the structural and functional integrity of the quail (Coturnix coturnix japonica) sperm plasma membrane

1. The objectives of this study were to establish the use of the fluorophores Hoechst 33342 and propidium iodide for the evaluation of sperm plasma membrane integrity and to identify an adequate hypoosmotic solution for the evaluation of sperm membrane functionality in quails.2. Sperm samples were collected from the vas deferens of nine quails. After initial evaluation, the samples were subjected to a flash-frozen assay. Three treatments with the following proportions of fresh sperm and sperm subjected to flash freezing were prepared as follows: 100:0 (T100), 50:50 (T50), and 0:100 (T0). The hypoosmotic swelling test used distilled water (0 mOsm/l) and fructose solutions (50, 100, and 200 mOsm/l).3. Immediately after recovery, the samples showed 75.6 ± 5.0% motility with vigour of 3.7 ± 0.3 and 96.1 ± 0.5% of the sperm appeared normal. The membrane integrity test showed 62.2 ± 5.2% intact sperm at T100, 29.0 ± 4.1% at T50 and 0.1 ± 0.1% at T0. Moreover, a greater number of reactive sperm (74.7 ± 6.7%) were observed when incubated in distilled water (0 mOsm/l) in comparison to other solutions (P < 0.05).4. The association of fluorescent probes composed of Hoechst 33342 and propidium iodide provided an efficient assessment of the integrity of the plasmatic membrane of quail spermatozoa. However, the study identified that the hypoosmotic swelling test has little predictive value regarding sperm membrane functionality in this species.

A non-randomized clinical trial to determine the safety and efficacy of a novel sperm sex selection technique

The desire to have offspring of a specific sex has a long history but has been particularly present with the appearance of assisted reproduction. However, embryo selection raises ethical concerns. Thus, several techniques to select sex-specific spermatozoa have been proposed but carry limitations. There are many variations of each technique, and some are time consuming and costly. Concerns about effectiveness and safety have also rendered many of them unappealing. Therefore, we propose a novel sperm sex selection technique (SST) that appears to be consistently safe and effective. A single-center, non-randomized clinical trial was designed. We included 1,317 couples, who were assigned to one of two groups: ICSI/PGTA or ICSI/PGTA+GS. Ejaculates from male partners of couples in the ICSI/PGTA+GS group (n = 105) were processed using SST to enrich spermatozoa for their desired sex. Standard sperm processing was carried out for couples undergoing PGT-A solely for aneuploidy (n = 1,212), comprising the ICSI/PGTA control group. To validate the efficacy of our technique, we performed an analysis on spermatozoa pre- and post-selection, followed by an assessment of the proportion of the conceptuses' sex to confirm clinical reliability. We also followed up on ICSI clinical outcomes and child/newborn health to establish the safety of our method. Our main outcome measures included the proportion of spermatozoa and embryos enriched for female and male sex, as well as embryo euploidy rates and ICSI clinical outcomes. These outcomes were compared between the two groups. For the ICSI/PGTA group (n = 1,212) (maternal age, 37.0±4yrs; paternal age, 39.1±6yrs), with ejaculated spermatozoa processed in the standard fashion, 2,303 ICSI cycles (1.2±1) yielded an 81.0% (14,375/17,737) fertilization. PGT-A results indicated a euploidy rate of 73.1% (n = 3,718) for female and 72.4% (n = 3,054) for male embryos. These couples achieved a 76.4% (699/915) implantation and 65.2% (597/915) clinical pregnancy rate, with 551 deliveries (48.5% female, 51.5% male). All 105 men in the ICSI/PGTA+GS group had sperm specimens with an equal sex distribution at baseline. Of them, 59 (paternal age, 40.9±6yrs) who desired female offspring obtained an 81.6% enrichment after SST. They underwent 73 ICSI cycles with their partners (maternal age, 37.9±4yrs), achieving a 77.3% (583/754) fertilization. This resulted in 79.1% (231/292) female embryos that generated a 79.3% (23/29) implantation rate, with 16 singleton deliveries of the desired female sex without major or minor congenital malformations. Forty-six couples (maternal age, 37.3±4yrs; paternal age, 40.7±6yrs) desiring male offspring obtained an 80.8% sperm sex enrichment. They underwent 50 ICSI cycles, achieving a 75.4% (462/613) fertilization and equivalent proportion of male embryos (223/280, 79.6%). Their implantation was 90.5% (19/21), with 13 singleton deliveries of healthy male offspring. Furthermore, 78.8% (182/231) of female and 66.4% (148/223) of male embryos from the ICSI/PGTA+GS cohort were euploid. These euploid rates were comparable to those from the ICSI/PGTA group. In couples undergoing ICSI with PGT-A, SST consistently enriched spermatozoa, resulting in a higher proportion of embryos and thus offspring of the desired sex. Moreover, SST did not impair the fertilization or embryo developmental competence of spermatozoa, nor did it affect offspring health. Trial registration: Clinicaltrials.gov NCT05500573.

Virus removal from semen with a pinched flow fractionation microfluidic chip

Nowadays pigs are bred with artificial insemination to reduce costs and transportation. To prevent the spread of diseases, it is important to test semen samples for viruses. Screening techniques applied are enzyme-linked immunosorbent assays and/or polymerase chain reaction, which are labor-intensive and expensive methods. In contrast to the current used screening techniques, it is possible to remove viruses physically from semen. However, existing methods for virus removal techniques have a low yield of spermatozoa. Therefore, we have developed a microfluidic chip that performs size-based separation of viruses and spermatozoa in boar semen samples, thereby having the potential to reduce the risk of disease spreading in the context of artificial insemination in the veterinary industry. As the head of a spermatozoon is at least twenty times larger than a virus particle, the particle size can be used to achieve separation, resulting in a semen sample with lower viral load and of higher quality. To achieve the size separation, our microfluidic device is based on pinched-flow fractionation. A model virus, cowpea chlorotic mottle virus, was used and spiked to porcine semen samples. With the proposed microfluidic chip and the optimized flow parameters, at least 84 ± 4% of the model viruses were removed from the semen. The remaining virus contamination is caused by the model virus adhering to spermatozoa instead of the separation technique. The spermatozoa recovery was 86 ± 6%, which is an enormous improvement in yield compared to existing virus removal techniques.

Fluorescent labelling of boar spermatozoa for quantitative studies on competitive sperm-oviduct binding

Invitro sperm-oviduct binding assays enable assessment of the capacity of spermatozoa to form a 'reservoir' in the oviduct. Competitive approaches, such as experimental set-ups that test multiple males or semen samples simultaneously on the same tissue explants, are desirable because they reduce the likelihood of bias when using material from different females. Therefore, we established a fluorescent labelling technique that allows tagging and storage of spermatozoa before competitive studies of sperm-oviduct binding invitro. Fluorescent markers were tested for reliability and compatibility with parameters of boar spermatozoa viability. The addition of seminal plasma after density gradient centrifugation was essential to counteract centrifugation stress during the labelling procedure. It was demonstrated that sperm tagged with MitoTracker Green FM or MitoTracker Red FM can be successfully used in competitive sperm-oviduct binding studies. The assay was sensitive enough to indicate subtle effects of semen storage temperature on the ability of the spermatozoa to contribute to the female sperm reservoir.

Sex Manipulation Technologies Progress in Livestock: A Review

Sex manipulation technologies allow predetermination of the sex of animal offspring by altering the normal reproductive process. In livestock production, the difference in type and gender can translate into significant economic benefits, including alleviation of severe food shortages. In livestock, however, the commercial application of sex manipulation technologies is currently available for cattle only. In this review, we described the brief history of sex manipulation, and the research progresses of common methods used in sex manipulation thus far. Information presented in this review can inform future studies on expanding the scope and use of sex manipulation technologies in livestock.

Bovine Sperm Sexing Alters Sperm Morphokinetics and Subsequent Early Embryonic Development

In artificial insemination the use of sex-sorted bovine sperm results in reduced conception, the causes of which are only partly understood. Therefore, we set out to investigate the effects of sexing on bovine sperm function and early embryonic development. Computer-assisted semen analysis (CASA) of sperm of the same bulls (n = 5), before and after sexing, demonstrated significantly reduced fast (A) and slow (B) progressively motile sperm (p < 0.05) after sexing. Sexed-sperm also revealed significantly less hyperactivated sperm (p < 0.05). As shown by time-lapse videomicroscopy of in vitro produced embryos (n = 360), embryos derived from sexed-sperm displayed significantly increased incidences of arrest at the 4-cell stage (p < 0.05). The relative risk for shrinkage/fusion of blastomeres with subsequent lysis was 1.71 times higher in the embryos derived from sexed-sperm as compared to conventional embryos (p < 0.05) resulting in significantly reduced blastocyst rates (p < 0.001). The relative risk for cleavage was 2.36 times lower in the embryos derived from sex-sorted sperm (p < 0.001). Additionally, sexed-sperm-derived embryos showed reduced survival times (hazard ratio HR = 1.54, p < 0.001) which were bull dependent (p < 0.001). However, the percentage of apoptotic cells was similar to conventional embryos. Furthermore, embryos derived from sexed-sperm were found to reach developmental stages at similar timings as conventional embryos. Our results suggest that reduced conception rates after sexing are due to altered sperm morphokinetics, decreasing the chance of sperm to reach and fertilise the oocyte, and aberrant early embryonic development.

Bovine sperm sex-selection technology in Japan

BACKGROUND

In Japan, Livestock Improvement Association of Japan started commercially producing sexed bovine semen 10 years ago, and sexed bovine semen is currently used for the artificial insemination (AI) in the farms. In this review, the authors introduce the technology for sperm sexing by flow cytometry, the efforts at commercializing sexed semen in Japan, and recent field data on artificial insemination of the cattle with sexed semen.

METHODS

In the procedures of the flow cytometric method, X-chromosome-bearing sperm and Y-chromosome-bearing sperm were fluorescently stained, separated from each other by analyzing the difference in the DNA content, and cryopreserved. The authors surveyed the conception rates after AI with these sperm and sex ratios of the offspring with the cooperation from livestock associations, AI technicians, and farmers.

MAIN FINDINGS RESULTS

Although AI with sexed semen was associated with lower conception rates in comparison with AI with conventional semen, the accuracy of sex selection using AI with sexed semen was beyond >90%.

CONCLUSION

Sexed semen produced by flow cytometry has the potential to produce offspring of the preferred sex with high accuracy and reliability. Thus, it is expected that sexed semen is used for AI more frequently in the farms.

Seminal plasma affects sperm sex sorting in boars

Two experiments were conducted in boar semen samples to evaluate how both holding time (24h) and the presence of seminal plasma (SP) before sorting affect sperm sortability and the ability of sex-sorted spermatozoa to tolerate liquid storage. Whole ejaculate samples were divided into three aliquots immediately after collection: one was diluted (1:1, v/v) in Beltsville thawing solution (BTS; 50% SP); the SP of the other two aliquots was removed and the sperm pellets were diluted with BTS + 10% of their own SP (10% SP) or BTS alone (0% SP). The three aliquots of each ejaculate were divided into two portions, one that was processed immediately for sorting and a second that was sorted after 24h storage at 15-17°C. In the first experiment, the ability to exhibit well-defined X- and Y-chromosome-bearing sperm peaks (split) in the cytometry histogram and the subsequent sorting efficiency were assessed (20 ejaculates). In contrast with holding time, the SP proportion influenced the parameters examined, as evidenced by the higher number of ejaculates exhibiting split and better sorting efficiency (P<0.05) in semen samples with 0-10% SP compared with those with 50% SP. In a second experiment, the quality (viability, total and progressive motility) and functionality (plasma membrane fluidity and intracellular generation of reactive oxygen species) of sex-sorted spermatozoa were evaluated after 0, 72 and 120h storage at 15-17°C (10 ejaculates). Holding time and SP proportion did not influence the quality or functionality of stored sex-sorted spermatozoa. In conclusion, a holding time as long as 24h before sorting did not negatively affect sex sorting efficiency or the ability of sorted boar spermatozoa to tolerate long-term liquid storage. A high proportion of SP (50%) in the semen samples before sorting reduced the number of ejaculates to be sorted and negatively influenced the sorting efficiency, but did not affect the ability of sex-sorted spermatozoa to tolerate liquid storage.

Birth of puppies of predetermined sex after artificial insemination with a low number of sex-sorted, frozen-thawed spermatozoa in field conditions

The aim of this study was to evaluate fertility and sex ratios after artificial insemination in dogs under field conditions. Semen was cryopreserved as unsorted (control) or was separated into X- and Y-chromosome-bearing sperm using a cell sorter. Sixty female dogs were inseminated with frozen-thawed spermatozoa of 100 × 10⁶ unsorted (a dose in practice) and 4 × 10⁶ sorted (X and Y group, respectively). A total of 20 dogs became pregnant and 126 puppies were born from the three groups. The percentage of parturition was similar for the X (5/20; 25.0%) and Y (4/20; 20.0%) group (P > 0.05), but lower than controls (11/20; 55.0%) (P < 0.05). Ultimately 28 out of the 32 puppies produced from X group were female (87.5%) and 19/22 (86.4%) puppies of Y group were male. In contrast, sex ratio (51.4% to 48.6%) in the control was significantly different from the X, Y group (P < 0.05). However, male and female puppies in the control had similar birth weights and weaning weights to those from the X and Y groups. This preliminary information indicated that normal puppies of predicted sex can be produced with low numbers of sorted cryopreserved dog spermatozoa at a farm level, making sperm-sexing technology potentially applicable for elite breeding units.

Partial protection of N-acetylcysteine against MPA-capped CdTe quantum dot-induced neurotoxicity in rat primary cultured hippocampal neurons

CdTe QD exposure caused death and apoptosis of rat primary cultured hippocampal neurons via generating reactive oxygen species and increasing intracellular calcium levels, which could be reversed by a common antioxidant NAC.

High-resolution melt analysis does not reveal mutagenic risk in sexed sperm and in vitro-derived bovine embryos

The objectives of the present work were to verify whether simultaneous exposure to Hoechst 33342 and UV irradiation during sorting by flow cytometry may induce gene point mutations in bovine sperm and to assess whether the dye incorporated in the sperm may imply a mutagenic effect during the embryonic development. To this aim, high-resolution melt analysis (HRMA) was used to discriminate variations of single nucleotides in sexed vs. non-sexed control samples. Three batches of sorted and non-sorted commercial semen of seven bulls (42 samples) were subjected to HRMA. A set of 139 genes located on all the chromosomes was selected, and 407 regions of the genome covering a total of 83 907 bases were analyzed. Thereafter, sperm of one sexed and one non-sexed batch of each bull was used in in vitro fertilization, and the derived embryos were analyzed (n = 560). One hundred and thirty-three regions of the bovine genome, located in 40 genes, were screened for a total coverage of 23 397 bases. The comparison between the frequencies of variations, with respect to the sequences deposited, observed in the sexed and non-sexed sperm (843 vs. 770) and embryos (246 vs. 212) showed no significant differences (P > 0.05), as measured by chi-square tests. It can be concluded that staining with Hoechst 33342 and exposure to UV during sorting does not lead to significant changes in the frequencies of variants in the commercial sexed semen and in embryos produced in vitro with the same treated sperm.

Toxicity of nano molybdenum trioxide toward invasive breast cancer cells

Current chemotherapy is limited by the nature of invasive cancer cells, which are similar to cancer stem cells. Nanomaterials provide a potential alternate mode of cancer therapy. This study investigated the cytotoxicity of molybdenum trioxide (MoO3) nanoplates toward invasive breast cancer iMCF-7 cells by analyzing morphological changes and performing Western blot and flow cytometry analyses. The findings suggested that MoO3 exposure induces apoptosis and generates reactive oxygen species (ROS) in iMCF-7 cells. This study revealed the potential utility of MoO3 for treating metastatic cancer cells, which might enable advancements in cancer therapy.

FACS selection of valuable mutant mouse round spermatids and strain rescue via round spermatid injection

Round spermatid injection (ROSI) into mammalian oocytes can result in the development of viable embryos and offspring. One current limitation to this technique is the identification of suitable round spermatids. In the current paper, round spermatids were selected from testicular cells with phase contrast microscopy (PCM) and fluorescence-activated cell sorting (FACS), and ROSI was performed in two strains of mice. The rates of fertilization, embryonic development and offspring achieved were the same in all strains. Significantly, round spermatids selected by PCM and FACS were effectively used to rescue the infertile Pten-null mouse. The current results indicate that FACS selection of round spermatids can not only provide high-purity and viable round spermatids for use in ROSI, but also has no harmful effects on the developmental capacity of subsequently fertilized embryos. It was concluded that round spermatids selected by FACS are useful for mouse strain rederivation and rescue of infertile males; ROSI should be considered as a powerful addition to the armamentarium of assisted reproduction techniques applicable in the mouse.

Type 1 IFN inhibits the growth factor deprived apoptosis of cultured human aortic endothelial cells and protects the cells from chemically induced oxidative cytotoxicity

It has been shown that the genesis of atherosclerotic lesions is resulted from the injury of vascular endothelial cells and the cell damage is triggered by oxygen radicals generated from various tissues. Human vascular endothelial cells can survive and proliferate depending on growth factors such as VEGF or basic FGF and are induced apoptosis by the deprivation of growth factor or serum. It was found that type 1 IFN inhibits the growth factor deprived cell death of human aortic endothelial cells (HAEC) and protects the cells from chemically induced oxidative cytotoxicity. The anti-apoptotic effects of type 1 IFN were certified by flow cytometry using annexin-V-FITC/PI double staining and cell cycle analysis, fluorescence microscopy using Hoechst33342 and PI, colorimetric assay for caspase-3 activity, p53 and bax mRNA expressions, and cell counts. It was considered that IFN-β inhibits the executive late stage apoptosis from the results of annexin-V-FITC/PI double staining and the inhibition of caspase-3 activity, and that the anti-apoptotic effect might be owing to the direct inhibition of the apoptotic pathway mediated by p53 from the transient down-regulation of bax mRNA expression. Whereas, type 1 IFN protected the cells from the oxidative cytotoxicity induced by tertiary butylhydroperoxide (TBH) under the presence of Ca(2+). The effects of IFN-β is more potent inhibitor of cell death than IFN-α. These results indicate that type 1 IFN, especially IFN-β may be useful for the diseases with vascular endothelium damage such as atherosclerosis or restenosis after angioplasty as a medical treatment or a prophylactic.

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.

Improved quality of sex-sorted sperm: a prerequisite for wider commercial application

To date the only successful method to sort sperm into X- and Y-chromosome-bearing populations is the Beltsville Sperm Sexing Technology. Fertility results continue to be variable even though the technology has been used in a commercial setting for nearly a decade. This is at least partly due to the reduced lifespan of sperm after sorting and freezing. Several technical and biological factors are responsible for this problem. Furthermore, to meet economic demands, only 10-15% of the number of sperm (compared to unsexed semen) are loaded in each straw, further limiting the chances for fertilization. A new protocol for preservation of bull sperm, utilizing Sexcess shows promise in extending the lifespan of sorted bull sperm. Motility and acrosome integrity are significantly increased using Sexcess. Conception rates achieved with heifers for those bulls tested with Sexcess and using a standard AI regime give results that do not differ from results achieved using regular AI. In addition to the improvements of the sorting technology itself, we recommend a thorough pre-selection of bulls. A reliable prediction method to determine whether a bull is suitable for a sex-sorting program still does not exist. Such a test is needed, especially for "custom sorting" programs. Currently, test sorts are the only means of obtaining information about the sorting efficiency of semen from a particular bull.

Sex Preselection in Bovine by Separation of X- and Y-Chromosome Bearing Spermatozoa

Flow cytometrically-sorted sperm has been involved in the production of sex preselected offspring. More than 30,000 bovine offspring have been produced using AI and other means using spermatozoa separated by flow cytometer. Flow cytometric sperm sorting based on differences in their DNA content is the best method for separation of X- and Y-chromosome bearing spermatozoa. At first, flow cytometers were modified for DNA confirmation and sorting of sperm with high resolution. The beveled insertion needle can regulate orientation of flat-shaped bull sperm heads. The forward fluorescence detector is essential for measuring the DNA content of sperm. Recently, high-speed sperm sorting with orienting nozzles has resulted in production of 90% pure X- and Y-sperm at rate of 15-20 million sperm per hour. Application of this new technique will enable conduct of more conventional technologies for both artificial insemination and cryopreservation in the bovine and in other farm animals using X- or Y-sperm.

Influence of swim-up time on the ratio of X- and Y-bearing spermatozoa

OBJECTIVE

The objective was to examine the separation of X- and Y-bearing spermatozoa in a modified swim-up procedure using fluorescent in situ hybridization (FISH), and to find out the influence of swim-up time on the ratio of X- and Y-bearing spermatozoa.

STUDY DESIGN

Prospective study.

SETTING

Reproductive testing laboratory in a university hospital.

PATIENTS

Normal spermatozoa samples were obtained from 10 volunteers by masturbation after sexual abstinence for 3-5 days.

INTERVENTIONS

Spermatozoa were put into 18 tubes with 0.25 ml in each, then mixed with HTF medium and centrifuged for 5 min (400 x g). The supernatant was removed and discarded and 0.5 ml HTF was added slowly along the tube wall. Motile spermatozoa were collected after swimming up in different times (from 5 up to 150 min, with a total of 17 intervals). The X- and Y-bearing spermatozoa were determined using the FISH technique. The X/Y dual-color CEP probes that were marked by fluorescein isothiocyanate (FITC) and Texas red were applied to analyze the ratio of X- and Y-bearing spermatozoa. The FISH staining slides were analyzed under an immunofluorescence microscope. About 1000-1500 spermatozoa were counted per slide.

MAIN OUTCOME MEASURES

The percentages of X- and Y-bearing spermatozoa were calculated.

RESULTS

The study results suggested that the total ratio of hybridization was 98.33%. The ratio of X-bearing spermatozoa after swimming up for different amounts of time is 50.03 +/- 0.91% at 0 min, 50.45 +/- 2.06% after 15 min, 50.61 +/- 2.47% after 30 min, 50.16 +/- 2.67% after 60 min, 50.72 +/- 2.64% after 90 min, and 50.56 +/- 2.20% after 150 min. The statistical analysis showed that there were no significant differences among different swim-up times in the ratio of X-bearing spermatozoa.

CONCLUSIONS

There was no significant effect of swim-up time on the ratios of X- and Y-bearing spermatozoa using a modified swim-up procedure. No direct evidence was found that the swim-up procedure for separating motile spermatozoa to use for either intrauterine insemination (IUI) or in vitro fertilization (IVF) would lead to an imbalance of boys and girls.

Effect of sex-sorting on the ability of fresh and cryopreserved bull sperm to undergo an acrosome reaction

Previous studies indicate that sex-sorted sperm exhibit different physiology, including fertilizing capacity, from non-sorted sperm. However, differences between X- and Y-bearing sperm in their ability to undergo an acrosome reaction have never been investigated. This study determined the ability of non-sorted and sex-sorted sperm to undergo the acrosome reaction prior to and after cryopreservation. Sperm were treated with dilauroylphosphatidylcholine (PC12) to induce the acrosome reaction and the percentages of live-acrosome-reacted sperm and dead sperm were evaluated. The X- and Y-bearing sperm reacted similarly to the PC12 treatment, regardless of whether sperm were assessed prior to or after cryopreservation. Fresh control sperm exhibited lower percentages of live sperm (60%) than either X- or Y- sorted sperm (69-74%, P<0.05). Percentages of live control sperm were also lower after thawing (29-35%) than sex-sorted sperm (55-58%, P<0.05). Control and sex-sorted fresh sperm responded similarly to PC12 treatment. However, sex-sorted cryopreserved sperm exhibited higher percentages of live-acrosome-reacted sperm (23%) than control sperm (9%, P<0.05) after 40 min without PC12 treatment. In addition, cryopreserved control sperm treated with 79 microM PC12 exhibited higher percentages of live-acrosome-reacted sperm than sex-sorted sperm. In conclusion, X- and Y-bearing sperm responded similarly to PC12 treatment. In addition, fresh sexed and non-sorted sperm responded similarly to PC12 treatment. However, cryopreserved sex-sorted sperm underwent an acrosome reaction more rapidly in the absence of PC12 (over a 40 min period) than the non-sorted sperm. Therefore, sex-sorting induced changes in sperm membranes that accelerated the acrosome reaction process in sperm after cryopreservation.

Flow cytometric sexing of mammalian sperm

This review reexamines parameters needed for optimization of flow cytometric sexing mammalian sperm and updates the current status of sperm sexing for various species where this technology is currently being applied. Differences in DNA content have provided both a method to differentiate between these sex-determining gametes and a method to sort them that can be used for predetermining sex in mammals. Although the DNA content of all cells for each mammalian species is highly conserved, slight but measurable DNA content differences of sperm occur within species even among cattle breeds due to different sizes of Y-chromosomes. Most mammals produce flattened, oval-headed sperm that can be oriented within a sorter using hydrodynamic forces. Multiplying the percentage the difference in DNA content of the X- or Y-chromosome bearing sperm times the area of the flat profile of the sperm head gives a simple sorting index that suggests that bull and boar sperm are well suited for separation in a flow sorter. Successful sperm sexing of various species must take into account the relative susceptibilities of gametes to the stresses that occur during sexing. Sorting conditions must be optimized for each species to achieve acceptable sperm sexing efficiency, usually at 90% accuracy. In the commercial application of sperm sexing to cattle, fertility of sex-sorted bull sperm at 2 x 10(6)/dose remains at 70-80% of unsexed sperm at normal doses of 10 to 20 x 10(6) sperm. DNA content measurements have been used to identify the sex-chromosome bearing sperm populations with good accuracy in semen from at least 23 mammalian species, and normal-appearing offspring have been produced from sexed sperm of at least seven species.

An update on Reproductive Technologies with Potential Short-Term Application in Pig Production

Over the past decade, there has been an increase in the development and/or in the improvement of emerging reproductive technologies in pigs. Among emerging reproductive technologies with potential short-term application in pig production are: artificial insemination with low number of spermatozoa, cryopreservation of spermatozoa and embryos, sperm sexing, and non-surgical embryo transfer. The following review will give emphasis to recent advancements in these reproductive technologies that are starting to show possibilities of serious applications under field conditions.

Effect of staining and sorting on boar sperm membrane integrity, mitochondrial activity and in vitro blastocyst development

The objective of this study was to determine the effects of staining with Hoechst 33342 and of the entire sorting procedure on boar sperm membrane integrity (using Annexin-V/PI), mitochondrial activity (using JC-1/SYBR/PI) and blastocyst development in vitro; the effect of storage at 17 degrees C for 24h prior to Hoechst staining and sorting was also investigated. The Hoechst staining and the whole sorting procedure reduced the percent of live spermatozoa in both fresh (day 0) and stored (day 1) semen, as determined by both assays; nevertheless, there was no increase in live sperm cells showing signs of early damage (Annexin-V positive, propidium negative), whose percentages remained nearly zero. The majority of Annexin-V positive cells were propidium positive, therefore dead. JC-1 staining evidenced a correlation between mitochondrial activity and viability. However, a significant difference between viable sperm cells and sperm cells with active mitochondria was detected in control and stained sperm, whereas almost all viable sorted spermatozoa had active mitochondria. No significant differences in the in vitro produced blastocysts both on day 0 and 1 were observed. In conclusion, despite the damages induced by sorting procedures, semen sorted as fresh or after storage at 17 degrees C can be successfully used for in vitro production of pig embryos.