Fertility after post-cervical artificial insemination with cryopreserved sperm from boar ejaculates of good and poor freezability

This study compared the field fertility outcomes in frozen–thawed (FT) sperm from boar ejaculates with different freezability (good, GFE/poor, PFE) while testing the reliability of the post-cervical artificial insemination (post-CAI) in FT sperm. The assay was conducted over eight months with 86 weaned sows being inseminated by post-CAI. Every ejaculate in a total of 26 from 15 Piétrain boars was divided into a refrigerated semen portion (FS; control treatment) and a cryopreserved portion (FT sperm), and the ejaculates were in turn classified as GFE or PFE in function of the sperm progressive motility and viability at 240 min post-thaw. As result, one of four possible treatments was randomly given to each sow: FS-GFE, FS-PFE, FT-GFE and FT-PFE. The number of pregnant and farrowing sows in FT-GFE did not significantly differ from those of FS control treatments. Contrarily, the probabilities of pregnancy were two times lower after inseminations with FT-PFE (P < 0.05) compared to FT-GFE, which indicates that ejaculates with high post-thaw sperm progressive motility and viability are more likely to result in pregnancies than those with poor in vitro sperm function. There were no differences in litter size or the risk of backflow among treatments. Further trials are required to determine the optimal volume and concentration of FT sperm in post-CAI to obtain a more reliable method for farmers interested in cryopreserved sperm.     

Rosmarinic acid improves function and in vitro fertilising ability of boar sperm after cryopreservation

During cryopreservation, oxidative stress exerts physical and chemical changes on sperm functionality. In the present study we investigated the antioxidant effect of rosmarinic acid (RA) on quality and fertilising ability of frozen–thawed boar spermatozoa. Ejaculates collected from mature boar were cryopreserved in lactose–egg yolk buffer supplemented with different concentrations of RA (0 μM, 26.25 μM, 52.5 μM and 105 μM). Motion parameters, acrosome and plasma membrane integrity, lipoperoxidation levels, DNA oxidative damage (8-hydroxy-2-deoxyguanosine base lesion) and in vitro fertilisation ability were evaluated. Total and progressive motility were significantly higher in experimental extenders with RA than in the control (P < 0.05) at 0 and 120 min post-thawing. The plasma and acrosomal membrane integrity were improved by supplementation with 105 μM RA (P < 0.05). Negative correlation between RA and malondialdehyde (MDA) concentration were determined (P < 0.05). After thawing, the percentage of spermatozoa with oxidised DNA did not differ between extenders, however, at 120 and 240 min post-thawing, the samples supplemented with 105 μM RA showed the lowest DNA oxidation rate (P < 0.05). The penetration rate was significantly higher on spermatozoa cryopreserved with 105 μM RA (P < 0.05). The results suggest that RA provides a protection for boar spermatozoa against oxidative stress during cryopreservation by their antioxidant properties.     

Anti-oxidant supplementation improves boar sperm characteristics and fertility after cryopreservation: Comparison between cysteine and rosemary (Rosmarinus officinalis)

Anti-oxidants partially ameliorated the detrimental effects of reactive oxidative substances produced during cryopreservation. The objective of the study was to determine the effect of anti-oxidant addition to the freezing extender on boar semen qualities and fertility capacity. Ejaculates were collected from a previously selected boar and semen samples were processed using the straw freezing procedure. In experiment 1, semen samples were cryopreserved in lactose-egg yolk solution supplemented with various concentrations of cysteine (0, 5 and 10 mM) to determinate a cysteine concentration capable of producing a protective effect during cryopreservation. Semen quality (total motility, progressive motility, viability, acrosome integrity and hypoosmotic swelling test) was evaluated after freezing and thawing and then every hour for 3 h. In experiment 2, ejaculates were cryopreserved with lactose-egg yolk extender with or without the following anti-oxidants: cysteine, rosemary (Rosmarinus officinalis) and cysteine plus rosemary. Semen quality was evaluated. In the experiment 3, fertility capacity of semen frozen in anti-oxidant supplementation extenders was examined in vitro. A total of 2232 oocytes were in vitro matured and inseminated with frozen-thawed sperm. In summary: (i) the effective concentration of cysteine in freezing extender was 10 mM; (ii) the addition of exogenous rosemary or cysteine to the freezing extender positively affected post-thawed viability and acrosome integrity. Only rosemary supplementation improved total motility at 3 h and progressive motility at any time; (iii) the inclusion of rosemary into the extender was effective in penetration and cleavage rate and also in the efficiency of the fertilization system.     

Effects of post-thaw incubation on motility,acrosomal integrity and in vitro fertilizing capacity of boar spermatozoa cryopreserved in 0.5 and 5 ml straws

The effect of post-thaw incubation (0 vs. 5 h at 15 °C) and straw size (5 vs. 0.5 ml) on motility, acrosomal integrity and in vitro fertilizing (IVF) capacity of cryopreserved boar spermatozoa was studied. In samples assessed immediately after thawing, no differences were found between the two straw sizes. After 5 h post-thaw incubation, all parameters, except polyspermy, decreased and, spermatozoa packaged in 5 ml straws showed better functional and IVF parameters than these in 0.5 ml straws.     

Relationship of sperm small heat-shock protein 10 and voltage-dependent anion channel 2 with semen freezability in boars

Freezability differences between boar ejaculates exist, but there is no useful method to predict the ejaculate freezability before sperm cryopreservation takes place. In this context, the present study sought to determine whether the amounts of small heat-shock protein 10 (also known as outer dense fiber protein 1) (ODF1/HSPB10) and voltage-dependent anion channel 2 (VDAC2) may be used as boar sperm freezability markers. With this aim, 26 boar ejaculates were split into two fractions: one for protein extraction and the other for cryopreservation purposes. Ejaculates were subsequently classified into two groups (good freezability ejaculates [GFE] and poor freezability ejaculates [PFE]) based on viability and sperm motility assessments after 30 and 240 minutes of after thawing. Although the VDAC2 amounts, analyzed through Western blot, were significantly higher (P < 0.01) in GFE (1.15 ± 0.18 density mm²) than in PFE (0.16 ± 0.03 density mm²), no significant differences were observed in ODF1/HSPB10 between both groups (i.e., 1.97 ± 0.38 density mm² in GFE vs. 1.87 ± 1.54 density mm² in PFE). In addition, principal component and multiple regression analyses indicated that the component explaining most of the variance (78.41%) in ejaculate freezability at 240 minutes after thawing resulted to be significantly (P < 0.05) correlated with VDAC2 content. This result revealed that the amounts of VDAC2 but not those of ODF1/HSPB10 may be used to predict the freezability of a given boar ejaculate before starting cryopreservation procedures.     

Missense variant in TPI1 (Arg189Gln) causes neurologic deficits through structural changes in the triosephosphate isomerase catalytic site and reduced enzyme levels in vivo

Mutations in the gene triosephosphate isomerase (TPI) lead to a severe multisystem condition that is characterized by hemolytic anemia, a weakened immune system, and significant neurologic symptoms such as seizures, distal neuropathy, and intellectual disability. No effective therapy is available. Here we report a compound heterozygous patient with a novel TPI pathogenic variant (NM_000365.5:c.569G>A:p.(Arg189Gln)) in combination with the common (NM_000365.5:c.315G>C:p.(Glu104Asp)) allele. We characterized the novel variant by mutating the homologous Arg in Drosophila using a genomic engineering system, demonstrating that missense mutations at this position cause a strong loss of function. Compound heterozygote animals were generated and exhibit motor behavioural deficits and markedly reduced protein levels. Furthermore, examinations of the TPI^Arg189Gln/TPI^Glu104Asp patient fibroblasts confirmed the reduction of TPI levels, suggesting that Arg189Gln may also affect the stability of the protein. The Arg189 residue participates in two salt bridges on the backside of the TPI enzyme dimer, and we reveal that a mutation at this position alters the coordination of the substrate-binding site and important catalytic residues. Collectively, these data reveal a new human pathogenic variant associated with TPI deficiency, identify the Arg189 salt bridge as critical for organizing the catalytic site of the TPI enzyme, and demonstrates that reduced TPI levels are associated with human TPI deficiency. These findings advance our understanding of the molecular pathogenesis of the disease, and suggest new therapeutic avenues for pre-clinical trials.     

Rhodiola sacra aqueous extract (RSAE) improves biochemical and sperm characteristics in cryopreserved boar semen

Although Rhodiola sacra aqueous extract (RSAE) has been used in many studies as an antioxidant, its effects on semen characteristics and its antioxidant properties during cryopreservation of boar sperm have never been evaluated. Semen was collected from five Duroc boars (2-4-year-old) twice weekly and frozen-thawed in extender with RSEA. Motion characteristics were assessed with a computer-aided semen analysis (CASA) system, whereas other sperm quality end points were assessed by routine methods. The effective concentration of RSEA in extender ranged from 4 to 8 mg/L and the effect of RSEA on sperm quality was better in glycerol-free extender than extender containing glycerol (P < 0.05). In frozen-thawed boar semen, there was a direct correlation (P < 0.05) between RSEA concentration and glutathione (GSH) concentrations, mitochondrial activity, and hypoosmotic swelling test (HOST), and an inverse correlation (r = −0.982, P < 0.05) between RSEA concentration and malondialdehyde (all end points were significantly higher at 6 mg/L than in the control group). In summary: (i) the effective concentration of RSEA in extender ranged from 4 to 8 mg/L; (ii) the effect of RSEA on sperm quality was better in extender without glycerol; and (iii) there was a significant correlation between RSEA concentrations and concentrations of GSH and MAD in frozen-thawed boar semen (antioxidant effects of RSEA were concentration-dependent). Further studies are needed to define the active ingredient in RSEA that protects boar sperm against ROS.     

Sperm binding glycoprotein (SBG) produces calcium and bicarbonate dependent alteration of acrosome morphology and protein tyrosine phosphorylation on boar sperm

The oviduct is a dynamic organ which modulates gamete physiology. Two subpopulations of sperm have been described in the oviduct of sows, a majority with normal appearance in the deep furrows and a minority, centrally located, and showing damaged membranes. Sperm-oviduct interaction provides the formation of a sperm storage and allows the selection of sperm with certain qualities. Pig (Sus scrofa) oviductal sperm binding glycoprotein (SBG) binds to sperm and exposes Gal beta1-3GalNAc. This disaccharide may be recognized by boar spermadhesin AQN1, which seems to be involved in sperm interaction with the oviduct. SBG is present at the apical surface of the epithelial cells that surround the lumen of the oviduct rather than at the bottom of the crypts. These characteristics imply it could be involved in sperm interaction with this organ. In this study, we evaluate the effect of SBG over boar sperm. We show that the presence of SBG produces alterations of the acrosome morphology of sperm only when they are incubated in capacitating conditions. SBG binds to the periacrosomal region of sperm undergoing capacitation. Its presence induces an increase on the tyrosine-phosphorylation of a polypeptide of apparent molecular mass 97 kDa, as occurs with a 95 kDa protein in other mammalian sperm upon acrosomic reaction. Altogether, these results suggest that SBG might be involved in sperm selection by alteration of the acrosome of sperm that have already begun the capacitation process when they arrive to the oviduct.     

Remating, sperm transfer, and sperm displacement in the cactophilic species Drosophila buzzatii Patterson & Wheeler (Diptera: Drosophilidae)

The mating system of Drosophila buzzatii is characterized by short copulation duration, frequent remating in both males and females, and male ejaculate partitioning. Additional features of the system are strong sperm displacement and a high frequency of sterile matings. Remating frequencies and the effects of remating on various mating parameters were studied. In order to characterize variation, five isofemale lines from geographically distant localities in Australia (three localities), Brazil and the Canary Islands were used. Mating parameters studied were: premating time, copulation duration, interval between successive matings, and progeny number as a measure of sperm transfer. Variation for sperm displacement was studied in crosses between laboratory stocks and a number of isofemale lines from Australia. There were significant between‐line differences in female remating frequencies, premating time, copulation duration, interval between successive matings, and progeny numbers, indicating genetic variation for these traits. Females from the five lines mated on average 1.6 to 3.1 times in 4 h, with a maximum of eight matings for one female. The males were given a maximum of ten virgin females in sequence and more than one‐third of the males mated all ten females in the 2 h observation period. Copulation duration decreased and interval between matings increased with copulation number in multiply mated males. Mean copulation duration was c. 2 min. Sperm transfer, measured as the average number of progeny from a single mating, was low (c. 25) and multiply mated females gave more progeny than single mated females, although with much lower progeny numbers than observed in wild‐caught non‐virgin females. A surprisingly high proportion of observed matings gave no progeny, i.e. they were sterile matings. Sperm displacement was strong in most crosses and remained strong in multiply mated females. The results are discussed in relation to the evolution of mating patterns in Drosophila.     

Effect of glycerol concentration, Equex STM® supplementation and liquid storage prior to freezing on the motility and acrosome integrity of frozen-thawed epididymal alpaca (Vicugna pacos) sperm

Two experiments were conducted to determine the effects of glycerol concentration and Equex STM® paste on the post-thaw motility and acrosome integrity of epididymal alpaca sperm. In Experiment 1, epididymal sperm were harvested from male alpacas, diluted, and cooled to 4 °C in a Lactose cooling extender, and pellet-frozen in a Lactose cryodiluent containing final glycerol concentrations of 2, 3, or 4%. In Experiment 2, epididymal sperm were diluted in Biladyl®, cooled to 4 °C, stored at that temperature for 18-24 h, and further diluted with Biladyl® without or with Equex STM® paste (final concentration 1% v:v) before pellet freezing. In Experiment 1, sperm motility was not affected by glycerol concentration immediately (2%: 16.1 ± 4.6%; 3%: 20.5 ± 5.9% and 4%: 18.5 ± 6.6%; P > 0.05) or 3h post thaw (< 5% for all groups; P > 0.05). Post-thaw acrosome integrity was similar for sperm frozen in 2% (83.6 ± 1.6%), 3% (81.3 ± 2.0%) and 4% glycerol (84.8 ± 2.0%; P > 0.05) but was higher 3h post-thaw for sperm frozen in 3% (75.7 ± 3.8%) and 4% (77.2 ± 4.1%) than 2% glycerol (66.9 ± 2.7%; P < 0.05). In Experiment 2, sperm motility was higher immediately after thawing for sperm frozen in the presence of Equex STM® (Equex®: 21.5 ± 3.5%; control: 14.4 ± 2.1%; P < 0.05) but was similar at 3h post-thaw (P > 0.05). Acrosome integrity was similar for sperm frozen with or without Equex STM® paste immediately (control: 89.6 ± 1.2%; Equex®: 91.1 ± 1.4%; P > 0.05) and 3 h post-thaw (control: 69.3 ± 3.7%; Equex®: 59.9 ± 5.8%; P > 0.05). Sperm cryopreserved in medium containing 3-4% glycerol and 1% Equex STM® retained the best motility and acrosome integrity, even after liquid storage for 18-24 h at 4 °C prior to cryopreservation.     

Cryopreservation of red snapper (Lutjanus argentimaculatus) sperm: Effect of cryoprotectants and cooling rates on sperm motility, sperm viability, and fertilization capacity

Sperm cryopreservation of red snapper (Lutjanus argentimaculatus) is essentially unexplored, although many species of the Lutjanidae family are considered to be high-value commercial species. The objective of this study was to develop a species-specific cryopreservation protocol for red snapper (L. argentimaculatus) sperm by optimizing cryoprotectants and cooling rates in the cryopreservation procedure. Ten cryoprotectants at four concentrations and two freezing protocols were examined in two separate experiments. In the first experiment, toxicity studies of dimethyl sulfoxide (DMSO), glycerol, propylene glycol (PG), ethylene glycol (EG), formamide, methanol, ethanol, sucrose, trehalose, and dimethylacetamide (DMA) on sperm motility were performed. Semen diluted 1:1 in Ringer solution were exposed to cryoprotectants at four final concentrations of 5%, 10%, 15%, or 20% for periods of 10, 20, 30, 40, 50, 60, 90, and 120 min at room temperature (25 °C). The cryoprotectants and concentrations that showed the least toxic effect on sperm motility were selected for cryopreservation trials. In the second experiment, selected cryoprotectants were then assessed for freezing capacity of sperm as follows: DMSO 5% and 10%, PG 5% and 10%, EG 5% and 10%, ethanol 5%, and methanol 5%. Semen was diluted 1:1 in Ringer solution and equilibrated with selected cryoprotectants for 10 min at room temperature. Sperm were frozen in a controlled-rate programmable freezer at four cooling rates of 3, 5, 10, and 12 °C/min from an initial temperature of 25 °C to final temperatures of −40 or −80 °C before plunging into liquid nitrogen. Sperm equilibrated in 10% DMSO and cooled at a rate of 10 °C/min to a final temperature of −80 °C had the highest motility (91.1 ± 2.2%) and viability (92.7 ± 2.3%) after thawing. The fertilization rate of frozen-thawed sperm (72.4 ± 2.4%) was not different (P > 0.05) from that of fresh sperm (75.5 ± 2.4%). This study apparently represents the first reported attempt for cryopreservation of L. argentimaculatus sperm.     

The Azores bullfinch (Pyrrhula murina) has the same unusual and size‐variable sperm morphology as the Eurasian bullfinch (Pyrrhula pyrrhula)

The Azores bullfinch is endemic to the island of São Miguel in the Azores archipelago and the sister species to the Eurasian bullfinch. Here we show that the spermatozoa of the two species have similar ultrastructure and gross morphology. Thus, the unusual and supposedly neotenous sperm morphology previously described for the Eurasian bullfinch appears to be an ancestral trait that evolved before the two taxa diverged. In addition, the coefficients of variation in total sperm length, both within and among males, were high in both species and exceed any previously published values for free‐living passerines. Such high sperm‐size variation is typically found in species with relaxed sperm competition. However, the high variance in mean sperm length among Azores bullfinches is surprising, because the trait has high heritability and this small, insular population shows clear signs of reduced genetic diversity at neutral loci. A possible explanation for this apparent contradiction is that the Azores bullfinch has retained more diversity at functional and fitness‐related loci than at more neutral parts of the genome. Finally, we also present data on relative testis size and sperm swimming speed for the Eurasian bullfinch, and discuss the hypothesis that the small and putatively neotenous sperm in bullfinches has evolved in response to lack of sperm competition. © 2013 The Linnean Society of London     

Structure of sperm,spermatozeugmata and ‘lateral organs’ in the bivalve Arthritica (Galeommatoidea: Leptonidae)

The position and structure of paired ‘lateral organs’ in the foot of Arthritica semen and Arthritica bifurca might indicate a chemosensory function. In both species part of the organ is also glandular. In A. semen the glandular epithelium is detached piecemeal and, probably by means of the foot, is moved to and grafted upon the gills of the same individual. The transferred epithelia appear as disk‐shaped actively secretory ‘gill bodies’ which, attached to the abfrontal side of the inner demibranch, replace the ordinary unciliated gill epithelium. The secretion is liberated into the suprabranchial chamber, which serves as a marsupium, but its function is uncertain. Arthritica semen is a protandric hermaphrodite and produces very large ova that undergo a direct development that results in a non‐planktonic lecithotrophic crawling juvenile stage. The sperm cells have filiform nuclei that are straight in the euspermatozoa and more or less helicoidal in what is considered to represent paraspermatozoa. By a process of aggregation, spermatozeugmata are formed which consist exclusively either of euspermatozoa or paraspermatozoa. Spermatozoa are stored in the oviduct in A. semen but in paired seminal receptacles in A. bifurca.     

A novel sperm adaptation to evolutionary constraints on reproduction: Pre‐ejaculatory sperm activation in the beach spawning capelin (Osmeridae)

Reproduction of external fertilizing vertebrates is typically constrained to either fresh or salt water, not both. For all studied amphibians and fishes, this constraint includes immotile sperm that are activated after ejaculation only by the specific chemistry of the fertilizing medium in which the species evolved (fresh, brackish, or salt water). No amphibians can reproduce in the sea. Although diadromous fishes may migrate between salt and fresh water, they are shackled to their natal environment for spawning in part because of sperm activation. Here, we report for the first time among all documented external fertilizing vertebrates, that in the absence of any external media, sperm are motile at ejaculation in a marine spawning fish (Osmeridae, capelin, Mallotus villosus). To illuminate why, we evaluated sperm behavior at different salinities in M. villosus as well as the related freshwater spawning anadromous rainbow smelt (Osmerus mordax). Surprisingly, sperm performance was superior in fresh water for both species. M. villosus spend their entire life at sea but our results show that their sperm are deactivated by sea water, suggesting a freshwater ancestry. By circumventing constraining water chemistry, we interpret the unique pre‐ejaculatory sperm activation in this species as a novel adaptation that enables fertilization in the marine environment. These findings also contribute to understanding the persistence of anadromy, despite great energetic costs to adult fishes.     

Identification and characterization of P31m, a novel sperm protein in Cynomolgus monkey (Macaca fascicularis)

We have previously described a hamster sperm glycoprotein, P26h, which is implicated in the cascade of events occurring during the interaction between mature spermatozoa and the oocyte's zona pellucida. The P26h is acquired on the acrosomal cap of the spermatozoon during its maturation arising within the epididymis. Lately, using a polyclonal antiserum raised against P26h, a 34 kDa protein, P34H, has been identified on the acrosomal cap of the human spermatozoon. The cloning and sequencing of the cDNA encoding P34H has revealed a 65% similarity between the P34H and P26h amino acid sequences. Considering that P26h shows total immunocontraceptive properties in the hamster, it is of relevant importance to have an animal model phylogenetically closer to the human. Using the Cynomolgus monkey, we searched for a protein autologous to the human P34H. A 31 kDa protein, the P31m, localized on the acrosomal cap of the monkey spermatozoon has been identified by a Western blot analysis and by immunohistochemical techniques using an anti-hamster P26h antiserum. Northern blot analysis showed increasing high levels of the P31m mRNA through the epididymis and at lower levels in the testis. In situ hybridization showed the presence of the P31m mRNA in the principal cells of the epididymis. The cloning and sequencing of the cDNA encoding the P31m showed a high homology of 97% identity between the P31m and P34H nucleotidic sequences. This study clearly demonstrates that the monkey P31m is the homologous protein of the hamster P26h and of the human P34H. Mol. Reprod. Dev. 59: 431-441, 2001.     

Regional genetic variation in the major sperm protein genes of Onchocerca volvulus and Mansonella ozzardi (Nematoda: Filarioidea)

Onchocerca volvulus and Mansonella ozzardi are two human filarial parasites present in South and Central America. In the Brazilian Amazonia they are found in sympatry, and the lack of clear morphological diagnostic characters in the microfilariae hinders their identification. The major sperm protein (MSP) gene of both species has been sequenced and characterised to determine its potential as a molecular diagnostic character. The length of the MSP gene is different in each species, and this could be used to detect and differentiate them by running the polymerase chain reaction (PCR) product in an agarose gel. Two major gene groups were identified in O. volvulus with a genetic distance of 6% between them. In M. ozzardi only one major group of genes was observed. The high similarity between the protein amino acid sequence of both filarial species confirms that the MSP has been highly conserved through nematode evolution.     

A novel protein,sperm head and tail associated protein (SHTAP), interacts with cysteine‐rich secretory protein 2 (CRISP2) during spermatogenesis in the mouse

Background information. CRISP2 (cysteine‐rich secretory protein 2) is a sperm acrosome and tail protein with the ability to regulate Ca²⁺ flow through ryanodine receptors. Based on these properties, CRISP2 has a potential role in fertilization through the regulation of ion signalling in the acrosome reaction and sperm motility. The purpose of the present study was to determine the expression, subcellular localization and the role in spermatogenesis of a novel CRISP2‐binding partner, which we have designated SHTAP (sperm head and tail associated protein). Results. Using yeast two‐hybrid screens of an adult testis expression library, we identified SHTAP as a novel mouse CRISP2‐binding partner. Sequence analysis of all Shtap cDNA clones revealed that the mouse Shtap gene is embedded within a gene encoding the unrelated protein NSUN4 (NOL1/NOP2/Sun domain family member 4). Five orthologues of the Shtap gene have been annotated in public databases. SHTAP and its orthologues showed no significant sequence similarity to any known protein or functional motifs, including NSUN4. Using an SHTAP antiserum, multiple SHTAP isoforms (～20–87 kDa) were detected in the testis, sperm, and various somatic tissues. Interestingly, only the ～26 kDa isoform of SHTAP was able to interact with CRISP2. Furthermore, yeast two‐hybrid assays showed that both the CAP (CRISP/antigen 5/pathogenesis related‐1) and CRISP domains of CRISP2 were required for maximal binding to SHTAP. SHTAP protein was localized to the peri‐acrosomal region of round spermatids, and the head and tail of the elongated spermatids and sperm tail where it co‐localized with CRISP2. During sperm capacitation, SHTAP and the SHTAP—CRISP2 complex appeared to be redistributed within the head. Conclusions. The present study is the first report of the identification, annotation and expression analysis of the mouse Shtap gene. The redistribution observed during sperm capacitation raises the possibility that SHTAP and the SHTAP—CRISP2 complex play a role in the attainment of sperm functional competence.