Effects of cryopreservation on phosphatidylserine translocation, intracellular hydrogen peroxide, and DNA integrity in canine sperm

Evaluating cryoinjury of canine spermatozoa is crucial to improving the probability of fertilization. Recently, studies on sperm ROS production, phospholipid scrambling, and DNA damage induced by cryopreservation have been reported. However, the consequences of cryopreservation on these crucial factors are lacking with respect to canine semen. Therefore, the current study was designed to investigate the effects of the freezing-thawing procedure on these factors in canine semen. Ejaculates from five dogs were cryopreserved and thawed. Spermatozoa before and after a freezing-thawing process were assessed for phosphatidylserine (PS) translocation (Annexin V [AN]/propidium iodide [PI] assay), intracellular H₂O₂ level (dichlorofluorescein [DCF]/PI assay), DNA integrity (sperm chromatin structure assay), and conventional sperm parameters. The freezing-thawing process decreased motility, viability, normal morphology, and membrane integrity in canine sperm (P < 0.05). The frozen-thawed semen also showed a decrease in AN−/PI− sperm (%) and an increase in the PS translocation index, the intracellular H₂O₂ level in the viable sperm fraction, and the DNA fragmentation compared with that of fresh semen (P < 0.05). In conclusion, the freezing-thawing procedure significantly affects PS translocation, the intracellular H₂O₂ level, and DNA integrity in canine semen, which may explain the lower fertilization rate and in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) outcome when frozen-thawed spermatozoa are used. It is therefore recommended that these parameters be used as an additional parameter for the assessment of sperm quality after freeze-thawing in canine semen.     

Reproductive performance of partial gonadectomized male African catfish, Clarias gariepinus broodstocks

This study was conducted to evaluate the effect of partial gonadectomy on reproductive performance of male Clarias gariepinus broodstock. Testes from C. gariepinus broodstock were surgically removed; 25% of the testes (Treatment 1), 50% of the testes (Treatment 2), 75% of the testes (Treatment 3), and removal of the sperm from the testes sac using syringe after the abdominal cavity had been cut open (Treatment 4) {control}. The incisions were sutured and the fish kept inside separate concrete tanks for 4 mo. The incisions closed up within 8 to 9 wk of surgery. The postsurgical survival of C. gariepinus was 100%, indicating the efficiency of the surgical procedure. There was no significant difference (P > 0.05) in sperm production, percentage fertilization, hatchability and survival of the larvae using sperm derived from regenerated testes of the partially gonadectomized C. gariepinus and nongonadectomized C. gariepinus. It also reveals that partial gonadectomy could not alter the quality of sperm production of C. gariepinus. Sperm derived from regenerated testes performed effectively for fertilization of eggs. Based on the results of this study, the removal of 75% of testes during partial gonadectomy proved to be the best as the total number of spermatozoa was more than that of other methods and the sperm was able to fertilize more eggs. Hence the removal of 75% of testis during partial gonadectomy of C. gariepinus is recommended based on the results of this study.     

Different sperm number in the spermatophores of Orchesella villosa (Geoffroy) (Entomobryidae) and Allacma fusca (L.) (Sminthuridae)

Members of the basal hexapod group Collembola perform indirect sperm transfer; males deposit spermatophores on the soil and these are then picked up by females for insemination. Orchesella villosa exhibits a dissociated mating behavior, while Allacma fusca has either associated mating behavior or, more commonly, produces spermatophores without pairing. Sperm ultrastructure in the two species has been studied by TEM and SEM observations to estimate the volume of these cells. The sperm number into each spermatophore has been determined by counting the fluorescent nuclei after Hoechst staining of sperm droplets squash preparations. Sperm droplets at the apex of spermatophores contain numerous spermatozoa of typical appearance, wound up and with a long anterior appendage (peduncle). Sperm droplets of Orchesella villosa are smaller (about 10 times) than in A. fusca, however they contain substantially more sperm cells (about three times). These differences could be explained as follows: (a) sperm of O. villosa are shorter than those of A. fusca (58 and 107 μm, respectively) and thus the volume of a single sperm of O. villosa is about 10 times smaller than in A. fusca; (b) considering the volume of sperm droplets and of sperm cells, the estimated number of sperm cells would be higher in A. fusca than in O. villosa; and (c) the conspicuous reduction of the sperm cells observed in A. fusca is likely linked to the aberrant meiosis present in this species, as well as in all Symphypleona studied so far, that causes a loss of 50% of their sperm.     

Sperm morphology and phylogeny of lagriids (Coleoptera,Tenebrionidae)

The systematics of tenebrionids remain unclear, principally at the subfamily level, as is the case of the Lagriinae. Considering that sperm morphology has contributed to the various insect group phylogenies, in this work we describe the structure and ultrastructure of these cells in Lagria villosa. Sperm in this species exhibit a strong morphological similarity to those of Tenebrio molitor and Tribolium castaneum, the only two species of Tenebrionidae with previously described sperm. In tenebrionids, the flagellar components offer good diagnostic characters, e.g. the symmetry of mitochondrial derivatives in L. villosa differentiates sperm of this species from those of Te. molitor and Tr. castaneum. However, the lateral association of the nucleus with flagellar components, the form of accessory bodies, and the presence of material connecting the axoneme to the accessory bodies and mitochondrial derivatives indicate that the three species form a sister group. Therefore, the sperm morphology of L. villosa support lagriid beetles as a subfamily (Lagriinae) of Tenebrionidae.     

RAC1 controls progressive movement and competitiveness of mammalian spermatozoa

Mammalian spermatozoa employ calcium (Ca²⁺) and cyclic adenosine monophosphate (cAMP) signaling in generating flagellar beat. However, how sperm direct their movement towards the egg cells has remained elusive. Here we show that the Rho small G protein RAC1 plays an important role in controlling progressive motility, in particular average path velocity and linearity. Upon RAC1 inhibition of wild type sperm with the drug NSC23766, progressive movement is impaired. Moreover, sperm from mice homozygous for the genetically variant t-haplotype region (t^w5/t^w32), which are sterile, show strongly enhanced RAC1 activity in comparison to wild type (+/+) controls, and quickly become immotile in vitro. Sperm from heterozygous (t/+) males, on the other hand, display intermediate RAC1 activity, impaired progressive motility and transmission ratio distortion (TRD) in favor of t-sperm. We show that t/+-derived sperm consist of two subpopulations, highly progressive and less progressive. The majority of highly progressive sperm carry the t-haplotype, while most less progressive sperm contain the wild type (+) chromosome. Dosage-controlled RAC1 inhibition in t/+ sperm by NSC23766 rescues progressive movement of (+)-sperm in vitro, directly demonstrating that impairment of progressive motility in the latter is caused by enhanced RAC1 activity. The combined data show that RAC1 plays a pivotal role in controlling progressive motility in sperm, and that inappropriate, enhanced or reduced RAC1 activity interferes with sperm progressive movement. Differential RAC1 activity within a sperm population impairs the competitiveness of sperm cells expressing suboptimal RAC1 activity and thus their fertilization success, as demonstrated by t/+-derived sperm. In conjunction with t-haplotype triggered TRD, we propose that Rho GTPase signaling is essential for directing sperm towards the egg cells.     

The effects of cryopreservation on the acrosome structure,enzyme activity,motility, and fertility of bovine,ovine, and goat sperm

The study was designed to investigate the effects of cryopreservation on bovine, ovine, and goat sperm motility, acrosome structure, enzyme activity, and fertilization ability. Percentage of sperm with hyaluronidase enzyme (HYD) activity was detected by a modified sodium hyaluronate-gelatin membrane. The N-α-benzoyl-DL-arginine-p-nitroanilide (BNPNA) method was used to assess the sperm acrosome enzyme (ACE). The mean percentage of sperm acrosome integrity dropped significantly (P < 0.01) after cryopreservation. The ACE activity of bovine sperm (100.48) was higher (P < 0.01) than that of ovine (57.88) or goat sperm (50.30), while the percentage of sperm with HYD activity of bovine (71.10%) and ovine (67.60%) sperm was higher than that of goat sperm (58.52%) after cryopreservation (P < 0.01). Sperm motility was positively correlated with the activity of the two acrosome enzymes before and after cryopreservation (P < 0.01). Cryopreservation had a negative effect on acrosomal morphology, motility, and acrosomal enzyme activity in their sperm. The fertilization ability of ovine and goat sperm decreased significantly after cryopreservation, but that of frozen bovine sperm did not differ significantly when compared with fresh sperm. There was no significant difference between ovine and goat sperm indices, except for percentage of sperm with HYD activity.     

Fine Structure of Sperm of Ekphymatodera thomasoni (Heteroderinae,Nemata)

Fine structure of developing sperm of the monospecific genus, Ekphymatodera, was compared with other Heteroderinae as part of a study to recognize diversity and phylogenetically informative characters within the subfamily. Sperm of Ekphymatodera originate from germ cells connected to a central rachis, a character which is shared with Globodera, but not with other Heteoderinae. In Ekphymatodera, and cyst-forming genera, a layer of cortical microtubules lies just beneath the surface of the plasma membrane. Sperm of Ekphymatodera are unique among Heteroderinae examined by the presence of spiral surface elevations on the filopodia, a character that may prove to be a synapomorphy for Sarisoderini. Fibrous bodies are abundant in spermatids; however, they do not persist in sperm of Ekphymatodera as they do in Meloidodera and Verutus. The male gonad of Ekphymatodera is lined by epithelial cells, which are greatly enlarged near the ejaculatory canal. These enlarged cells contain vesicles with concentric lamellar inclusions, not observed in other genera of the subfamily. Sperm of Heteroderinae are rich in diversity, and examination of additional representative species may indicate new phylogenetically informative characters.     

Fresh and frozen-thawed sperm quality, nuclear DNA integrity, invitro fertility, embryo development, and live-born offspring of N-ethyl-N-nitrosourea (ENU) mice

Efficient collection, freezing, reliable archiving of sperm, and re-derivation of mutant mice are essential components for large-scale mutagenesis programs in the mouse. Induced mutations (i.e. transgenes, targeted mutations, chemically induced mutations) in mice may cause inherited or temporary sterility, increase abnormal sperm values, or decrease fertility. One purpose of this study was to compare the effect(s) on fresh and frozen-thawed sperm quality, spermatozoa DNA integrity, unassisted in vitro fertility (IVF) rate, in vitro embryo development rate to blastocysts, and live-born offspring rates in non-ENU (control) animals and the F1-generation of N-ethyl-N-nitrosourea (ENU)-treated male mice (765 mg/kg C57BL6/J or 600 mg/kg 129S1/SvImJ total dose). The second purpose was to determine the effect(s) of parental oocyte donor strain on in vitro fertilization, in vitro embryo development to blastocysts, and live-born offspring rates using sperm and unassisted IVF to re-derive animals from non-ENU control and ENU mice. Sperm assessment parameters included progressive motility, concentration, plasma membrane integrity, membrane function integrity, acrosome integrity, and DNA integrity. There were no significant differences in fresh sperm assessment parameters, DNA integrity, unassisted in vitro fertility rate, in vitro embryo development rate to blastocysts, and live-born offspring rates between non-ENU and C3B6F1/J or B6129S1F1/J ENU mice. In addition, there were no significant differences in frozen-thawed sperm assessment parameters and DNA integrity rates for non-ENU control and ENU C3B6F1/J or B6129SF1/J mice. In vitro fertilization and in vitro embryo development to blastocysts were effected from strain genetic variability (P < 0.05). However, the cryopreservation process caused an increase of DNA fragmentation in non-ENU control and ENU C3B6F1/J or B6129S1F1/J hybrid mice compared to fresh control sperm (P < 0.01). Unlike the combinations of hybrid sperm and hybrid oocyte, increasing frozen-thawed sperm DNA fragmentation decreased the embryo development rate to blastocyst compared to fresh sperm when C57BL6, C3H, or 129S inbred mice were used as oocyte donors (P < 0.05).     

Complex female genitalia indicate sperm dumping in armored goblin spiders (Arachnida,Araneae, Oonopidae)

In promiscuous females, sperm ejection from the sperm storage site can be a strong mechanism to influence sperm priority patterns. Sperm dumping is reported from different animals including birds, insects, and humans. In spiders, it has been documented for four species including the oonopid Silhouettella loricatula. Oonopidae are a diverse spider family comprising many species with peculiar female genitalia. Especially in species where studies of mating behavior are difficult, morphological investigations of the genitalia help to understand their function and evolution. In the present study, the genitalia of the oonopids Myrmopopaea sp., Grymeus sp., and Lionneta sp. are investigated by means of histological serial sections and scanning electron microscopy (SEM). The results are compared with previous findings on S. loricatula. In Myrmopopaea sp. and Grymeus sp., the same morphological components are present that are involved in sperm dumping in S. loricatula. Inside the receptaculum, sperm are enclosed in a secretory sac which can be moved to the genital opening and dumped during copulation by muscle contractions. The female genitalia of Lionneta sp. are asymmetric. They show the same characteristics as S. loricatula but all the investigated females were unmated. The results strongly suggest that sperm dumping occurs in Myrmopopaea sp., Grymeus sp., and Lionneta sp. and happens by the same mechanism as in S. loricatula. Sperm dumping might even be common within a clade of oonopids. As in S. loricatula, the sperm transfer forms in the investigated species consist of several spermatozoa. Papillae with unknown function occur on the receptacula of all females.     

Semen characteristics of the swamp buffalo (Bubalus bubalis)

The semen characteristics were studied in 182 ejaculates collected with a bovine artificial vagina from five swamp buffalo (Bubalus bubalis) bulls. The mean values were: volume, 2.9 ml; general motility, 70.7%; live (unstained) sperm, 86.5%; abnormal sperm, 10.3%; intact acrosomes, 82.4%; sperm concentration, 1.06 × 10⁹cells/ml and total sperm/ejaculate, 3.18 × 10⁹cells/ml. Among the sperm abnormalities noted were “knobbed” acrosome, abaxial implantation, the “Dag” defect and the corkscrew midpiece. There were no significant (P > 0.05) monthly variations for any of the semen characteristics studied.     

Large-scale in vitro embryo production and pregnancy rates from Bos taurus, Bos indicus, and indicus-taurus dairy cows using sexed sperm

Herein we describe a large-scale commercial program for in vitro production of embryos from dairy Bos taurus, Bos indicus, and indicus-taurus donors, using sexed sperm. From 5,407 OPU, we compared the number of recovered oocytes (n = 90,086), viable oocytes (n = 64,826), and embryos produced in vitro from Gir (Bos indicus, n = 617), Holstein (Bos taurus, n = 180), 1/4 Holstein × 3/4 Gir (n = 44), and 1/2 Holstein-Gir (n = 37) crossbred cows, and the pregnancy rate of recipient cows. Viable oocytes were in vitro matured (24 h at 38.8 °C, 5% CO₂ in air) and fertilized by incubating them for 18 to 20 h with frozen-thawed sexed sperm (X-chromosome bearing) from Gir (n = 8) or Holstein (n = 7) sires (2 × 10⁶ sperm/dose). Embryos were cultured in similar conditions of temperature and atmosphere as for IVM, with variable intervals of culture (between Days 2 and 5) completed in a portable incubator. All embryos were transferred fresh, after 24 to 72 h of transportation (up to 2,000 km). On average, 16.7 ± 6.3 oocytes (mean ± SEM) were obtained per OPU procedure and 72.0% were considered viable. Total and viable oocytes per OPU procedure were 17.1 ± 4.5 and 12.1 ± 3.9 for Gir cows, 11.4 ± 3.9 and 8.0 ± 2.7 for Holstein cows, 20.4 ± 5.8 and 16.8 ± 5.0 for 1/4 Holstein × 3/4 Gir, and 31.4 ± 5.6 and 24.3 ± 4.7 for 1/2 Holstein-Gir crossbred females (P < 0.01). The mean number of embryos produced by OPU/IVF and the pregnancy rates were 3.2 (12,243/ 3,778) and 40% for Gir cows, 2.1 (2,426/1,138) and 36% for Holstein cows, 3.9 (1,033/267) and 37% for 1/4 Holstein × 3/4 Gir, and 5.5 (1,222/224), and 37% for 1/2 Holstein-Gir. In conclusion, we compared oocyte yield from two levels of indicus-taurus breeds and demonstrated the efficiency of sexed sperm for in vitro embryo production. Culturing embryos during long distance transportation was successful, with potential for international movement of embryos.     

A role for Acp29AB, a predicted seminal fluid lectin, in female sperm storage in Drosophila melanogaster

Females of many animal species store sperm for taxon-specific periods of time, ranging from a few hours to years. Female sperm storage has important reproductive and evolutionary consequences, yet relatively little is known of its molecular basis. Here, we report the isolation of a loss-of-function mutation of the Drosophila melanogaster Acp29AB gene, which encodes a seminal fluid protein that is transferred from males to females during mating. Using this mutant, we show that Acp29AB is required for the normal maintenance of sperm in storage. Consistent with this role, Acp29AB localizes to female sperm storage organs following mating, although it does not appear to associate tightly with sperm. Acp29AB is a predicted lectin, suggesting that sugar–protein interactions may be important for D. melanogaster sperm storage, much as they are in many mammals. Previous association studies have found an effect of Acp29AB genotype on a male's sperm competitive ability; our findings suggest that effects on sperm storage may underlie these differences in sperm competition. Moreover, Acp29AB's effects on sperm storage and sperm competition may explain previously documented evidence for positive selection on the Acp29AB locus.     

Effects of Nigella sativa L. seed oil on abnormal semen quality in infertile men: A randomized,double-blind,placebo-controlled clinical trial

In recent years, wide utilization of herbal drugs has encouraged scientists to determine their impressive effects on health. Since Nigella sativa L. seed (N. sativa) has many uses including infertility in traditional medicine, the effects of Nigella sativa L. seed oil on abnormal semen quality in infertile men with abnormal semen quality are of interest. This study was conducted on Iranian infertile men with inclusion criteria of abnormal sperm morphology less than 30% or sperm counts below 20 × 10⁶/ml or type A and B motility less than 25% and 50% respectively. The patients in N. sativa oil group (n = 34) received 2.5 ml N. sativa oil and placebo group (n = 34) received 2.5 ml liquid paraffin two times a day orally for 2 months. At baseline and after 2 months, the sperm count, motility and morphology and semen volume, pH and round cells as primary outcomes were determined in both groups. Results showed that sperm count, motility and morphology and semen volume, pH and round cells were improved significantly in N. sativa oil treated group compared with placebo group after 2 months. It is concluded that daily intake of 5 ml N. sativa oil for two months improves abnormal semen quality in infertile men without any adverse effects.     

Sperm competition games: Sperm size (mass) and number under raffle and displacement, and the evolution of P2

We examine models for evolution of sperm size (i.e. mass m) and number (s) under three mechanisms of sperm competition at low ‘risk’ levels: (i) raffle with no constraint on space available for competing sperm, (ii) direct displacement mainly by seminal fluid, and (iii) direct displacement mainly by sperm mass. Increasing sperm mass increases a sperm's ‘competitive weight’ against rival sperm through a diminishing returns function, r(m). ESS total ejaculate expenditure (the product m^?s^?) increases in all three models with sperm competition risk, q. If r(m), or ratio r′(m)/r(m), is independent of ESS sperm numbers, ESS sperm mass remains constant, and the sperm mass/number ratio (m^?/s^?) therefore decreases with risk. Dependency of sperm mass on risk can arise if r(m) depends on competing sperm density (sperm number / space available for sperm competition). Such dependencies generate complex relationships between sperm mass and number with risk, depending both on the mechanism and how sperm density affects r(m). While numbers always increase with risk, mass can either increase or decrease, but m^?/s^? typically decreases with risk unless sperm density strongly influences r(m). Where there is no extrinsic loading due to mating order, ESS paternity of the second (i.e. last) male to mate (P₂) under displacement always exceeds 0.5, and increases with risk (in the raffle P₂=0.5). Caution is needed when seeking evidence for a sperm size-number trade off. Although size and number trade-off independently against effort spent on acquiring matings, their product, m^?s^?, is invariant or fixed at a given risk level, effectively generating a size-number trade off. However, unless controlled for the effects of risk, the relation between m^? and s^? can be either positive or negative (a positive relation is usually taken as evidence against a size-number trade off).     

Phagocytosis of sperm by follicle cells of the carnivorous sponge Asbestopluma occidentalis (Porifera, Demospongiae)

During spermatogenesis of the carnivorous sponge Asbestopluma occidentalis, follicle cells that lined the spermatocysts phagocytosed unreleased mature sperm. Such follicle cells are part of the complex envelope that limits spermatocysts of A. occidentalis, which is also comprised of a collagen layer, a thick layer of intertwined cells, and spicules. Follicle cells showed vesicles containing single phagocytosed spermatozoa within their cytoplasm. Additionally, lipids and other inclusions were observed within the cytoplasm of follicle cells. It is likely that follicle cells recapture nutrients by phagocytosing spermatozoa and use them to form lipids and other inclusions. Such sperm phagocytosis is usually performed in higher invertebrates and vertebrates by Sertoli cells that are located in the testis wall. While Sertoli cells develop a wide range of functions such as creating a blood-testis barrier, providing crucial factors to ensure correct progression of spermatogenesis, and phagocytosis of aberrant, degenerating, and unreleased sperm cells, sponge follicle cells may only display phagocytotic activity on spermatogenic cells.     

Alterations of sperm DNA integrity during cryopreservation procedure and in vitro incubation of bull semen

An association between sperm DNA integrity and fertility was recently shown for frozen–thawed Norwegian Red (NRF) bull semen diluted in skimmed milk egg yolk (SMEY). In general the fertility of NRF cattle is high, however, in comparison with NRF semen in SMEY, NRF semen diluted in Tris EY based extenders has shown reduced fertility. The aim of the present study was to do a split-sample comparison of sperm DNA integrity of NRF bull semen (n = 20) in SMEY and Triladyl^® (Tris EY based) during routine cryopreservation procedure and during in vitro incubation of frozen–thawed semen in modified synthetic oviduct fluid (mSOF). In contrast to the high fertility of NRF cattle, Holstein cattle are experiencing a marked decline in fertility. Therefore, the present study also aimed to compare sperm DNA integrity of NRF (n = 20) and Holstein (n = 20) semen diluted in Triladyl^® during in vitro incubation. The sperm DNA integrity was measured by susceptibility to in situ acid induced denaturation by the Sperm chromatin structure assay (SCSA). Compared to initial values of frozen neat semen, an increase in DNA damage was observed after dilution and cooling (5 °C) and after freezing–thawing of NRF semen in SMEY, but only after freezing–thawing for NRF semen diluted in Triladyl^®. Sperm DNA damage of NRF semen increased during in vitro incubation in mSOF; the increase in percentage of spermatozoa with DNA damage was more prominent in SMEY than in Triladyl^®, while the degree of damage was higher in Triladyl^®, throughout the incubation period. However, while the correlation between DNA damage and sperm survival was negative in SMEY throughout the incubation period, a positive correlation was observed in Triladyl^® after 9 h of incubation, indicating a higher presence of DNA damage in the live sperm population. In comparison with Holstein spermatozoa, the sperm DNA integrity of NRF semen reflected a better ability to withstand alterations induced during in vitro incubation in mSOF. In conclusion, sperm DNA integrity of NRF bull semen was altered during the cryopreservation procedure and in vitro incubation in mSOF. Dilution in Triladyl^® maintained bull sperm DNA integrity better than dilution in SMEY. Furthermore, alterations in Holstein sperm DNA integrity was more pronounced during in vitro incubation in mSOF compared to NRF bull spermatozoa.     

Effect of sex sorting on CTC staining, actin cytoskeleton and tyrosine phosphorylation in bull and boar spermatozoa

Sperm sorting is a useful technology that permits sex preselection. It presents some troubles because of low fertility after the process. The main aim of this work was to analyze the putative existence of capacitation-like changes in both boar and bull sperm subjected to sex sorting that could lead to a detriment of semen quality. The parameters used were CTC staining patterns, actin cytoskeleton organization and tyrosine phosphorylation patterns; the last two were determined by both western blotting and immunofluorescence. Sex sorted spermatozoa were compared with fresh, in vitro capacitated and in vitro acrosome reacted sperm. In both species, sex sorted sperm showed a CTC staining pattern similar to that observed after in vitro capacitation. The actin pattern distribution after sperm sorting also tended to be similar to that observed after in vitro capacitation, but this effect was more pronounced in bull than in boar spermatozoa. However, actin expression analysis through western blot did not show any change in either species. The tyrosine phosphorylation pattern in boar sperm was practically unaltered after the sex sorting process, but in bulls about 40% of spermatozoa had a staining pattern indicative of capacitation. Additionally, western blotting analysis evidenced some differences in the expression of protein tyrosine phosphorylation among fresh, capacitated, acrosome reacted and sex sorted sperm cells in both species. Our results indicate that not all the sex-sorted-related modifications of the studied parameters were similar to those occurring after “in vitro” capacitation, thus suggesting that sex sorting-induced alterations of sperm function and structure do not necessarily indicate the achievement of the capacitated status of sorted sperm.     

The murine tub (rd5) mutation is not associated with a primary axonemal defect

Some genetic syndromes causing loss of hearing and vision, such as some forms of Usher’s syndrome, also cause reduced sperm cell motility, bronchiectasis, and other pathologies involving cilia- and flagella-bearing cells. In some Usher’s patients, ultrastructural defects of axonemes within photoreceptor ciliary bridges, nasal cilia, and sperm cell flagella have been found, indicating a primary defect of axonemal conformation. Mice homozygous for the tub (rd5) mutation exhibit progressive retinal degeneration, sensorineural hearing loss, reduced fertility, and obesity, and presently represent the only animal model with neuroepithelial degeneration of both cochlea and retina without other neurological abnormalities. They provide a good phenotypic match to human genetic sensory syndromes, particularly human sensory/obesity syndromes, such as Alstrom’s and Bardet/Biedl, although no human candidate genes have been identified. Because of their unique phenotype, tubby mice are an appropriate model in which to look for a primary axonemal defect. We studied the axonemal ultrastructure of photoreceptors and sperm cells and performed functional testing of sperm in tub/tub mice before and after the onset of obesity. Approximately 15% of photoreceptor axonemes appeared abnormal in tub/tub animals, compared to 0% in controls. Both tub homozygotes and controls exhibited approximately 10% abnormal sperm cell axonemes, and no differences in sperm cell motile function were found at any age. The modest occurrence of axonemal defects in photoreceptors of tub/tub animals is likely to be a secondary effect of retinal degeneration. We conclude that the tubby phenotype is not associated with a generalized defect of cilia- and flagella-bearing cells and that the tub mutation does not primarily affect axonemal structure.