Sperm Swimming Velocity Research Articles

Quality of cryopreserved salmonid semen is not affected by a 25 years storage period

The quality of rainbow trout (Oncorhynchus mykiss), charr (Salvelinus umbla), and brown trout (Salmo trutta) semen cryopreserved for 25 years was compared with semen cryopreserved for <3d. Investigated quality parameters were the sperm motility rate and swimming velocity, the percentage of sperm with intact membranes, with functional mitochondria, and without oxidative damages and the fertility rate and hatching rate of eggs fertilized with cryopreserved semen. Not any of the investigated quality parameters differed between semen cryopreserved for <3d and semen cryopreserved for 25 years. The data indicate that the quality of the cryopreserved fish semen did not change in dependence of the storage period. Thus establishes the efficiency and validity of sperm cryopreservation technologies for long-term storage in cryobanks.

Can cryptic female choice prevent invasive hybridization in external fertilizing fish?

Polyandrous mating systems result in females mating with multiple males, generating opportunities for strong pre-mating and post-mating sexual selection. Polyandry also creates the potential for unintended matings and subsequent sperm competition with hybridizing species. Cryptic female choice allows females to bias paternity towards preferred males under sperm competition and may include conspecific sperm preference when under hybridization risk. The potential for hybridization becomes particularly important in context of invasive species that can novelly hybridize with natives, and by definition, have evolved allopatrically. We provide the first examination of conspecific sperm preference in a system of three species with the potential to hybridize: North American native Atlantic salmon (Salmo salar) and brook char (Salvelinus fontinalis), and invasive brown trout (Salmo trutta) from Europe. Using naturalized populations on the island of Newfoundland, we measured changes in sperm swimming performance, a known predictor of paternity, to determine the degree of modification in sperm swimming to female cues related to conspecific sperm preference. Compared to water alone, female ovarian fluid in general had a pronounced effect and changed sperm motility (by a mean of 53%) and swimming velocity (mean 30%), but not linearity (mean 6%). However, patterns in the degree of modification suggest there is no conspecific sperm preference in the North American populations. Furthermore, female cues from both native species tended to boost the sperm of invasive males more than their own. We conclude that cryptic female choice via ovarian fluid mediated sperm swimming modification is too weak in this system to prevent invasive hybridization and is likely insufficient to promote or maintain reproductive isolation between the native North American species.

Toxicity of microplastics and triclosan, alone and in combination, to the fertilisation success of a broadcast spawning bivalve Tegillarca granosa

Since most marine invertebrates adopted external fertilisation, their fertilisation process is particularly vulnerable to aquatic pollutants. Both antimicrobial ingredients and microplastics (MPs) are ubiquitous in aquatic environments; however, their synergistic effects on the fertilisation of marine invertebrates remain unclear. Therefore, in this study, the fertilisation toxicity of MPs and triclosan (TCS), alone and in combination, was investigated in the broadcast spawning bivalve Tegillarca granosa. Results showed that MPs and TCS significantly suppressed the fertilisation success of T. granosa. As the fertilisation success of broadcast spawning invertebrates depends on successful gamete collisions, gamete fusion, and egg activation, sperm swimming velocity, viability, gamete collision probability, ATP status, and ion-transport enzyme activities were also analysed to further ascertain the underlying toxicity mechanisms. In summary, our findings indicate that the presence of MPs may enhance the fertilisation toxicity of TCS by hampering sperm-egg collision probability, reducing gamete fusion efficiency, and restricting Ca2+ oscillation formation.

The impact of percutaneous epididymal sperm aspiration (PESA) on sperm quality in mice.

In laboratory mice sperm quality is usually assessed in spermatozoa collected from the cauda epididymidis of freshly sacrificed males. Percutaneous epididymal sperm aspiration (PESA) is a non-terminal alternative that would allow repeated sperm collection for sperm quality assessment in living males. To test whether PESA is a suitable method to assess sperm quality, we compared sperm traits between samples collected by PESA versus the commonly applied terminal cauda epididymis dissection. The collected sperm samples were analyzed using computer assisted sperm analysis and various parameters, including sperm motility, swimming velocity and morphology were determined. We were able to retrieve motile sperm from all mice using PESA and the terminal cauda epididymis dissection. Based on computer assisted sperm analysis, however, sperm motility and swimming velocity were significantly lower after PESA compared to samples obtained by cauda epididymis dissection. In addition, we found significantly more morphological deformities in PESA samples, probably induced as a side effect of the sampling technique. Although sperm samples collected by PESA are successfully used for in vitro fertilizations, we cannot recommend PESA as a suitable method to assess sperm quality in mice, since the procedure seems to impair various sperm traits.

The effects of temperature and pH on the reproductive ecology of sand dollars and sea urchins: Impacts on sperm swimming and fertilization.

In an era of climate change, impacts on the marine environment include warming and ocean acidification. These effects can be amplified in shallow coastal regions where conditions often fluctuate widely. This type of environmental variation is potentially important for many nearshore species that are broadcast spawners, releasing eggs and sperm into the water column for fertilization. We conducted two experiments to investigate: 1) the impact of water temperature on sperm swimming characteristics and fertilization rate in sand dollars (Dendraster excentricus; temperatures 8-38°C) and sea urchins (Mesocentrotus franciscanus; temperatures 8-28°C) and; 2) the combined effects of multiple stressors (water temperature and pH) on these traits in sand dollars. We quantify thermal performance curves showing that sand dollar fertilization rates, sperm swimming velocities, and sperm motility display remarkably wide thermal breadths relative to red urchins, perhaps reflecting the wider range of water temperatures experienced by sand dollars at our field sites. For sand dollars, both temperature (8, 16, 24°C) and pH (7.1, 7.5, 7.9) affected fertilization but only temperature influenced sperm swimming velocity and motility. Although sperm velocities and fertilization were positively correlated, our fertilization kinetics model dramatically overestimated measured rates and this discrepancy was most pronounced under extreme temperature and pH conditions. Our results suggest that environmental stressors like temperature and pH likely impair aspects of the reproductive process beyond simple sperm swimming behavior.

Mutagenesis alters sperm swimming velocity in Astyanax cave fish

We investigated the hypothesis that intra ejaculate sperm competition screens against the transmission of deleterious alleles, including new mutants, from male parent to offspring. Recent investigations have established that sperm haploid genotypes can have major effects on sperm traits such as cellular robustness, longevity, and fertilization success. However, there is no evidence that new mutations can meaningfully affect sperm phenotypes. We tested this directly by comparing sperm from mutagenized and non-mutagenized control males in Astyanax fish. We used N-ethyl-N-nitrosourea (ENU) to induce single base substitutions in spermatogonial stem cells. We looked at swimming velocity, an important factor contributing to fertilization success, and flagellar length. Variability in swimming velocity was significantly higher in sperm from mutagenized males than in control sperm, reflecting their increased allelic diversity. In contrast, flagellar length, which is fixed during diploid stages of spermatogenesis, was unaffected by ENU treatment. We briefly discuss the implications of intra-ejaculate screening for maintenance of anisogamy and for outcomes of assisted reproductive technology.

Biophysical Determinants and Constraints on Sperm Swimming Velocity.

Over the last 50 years, sperm competition has become increasingly recognised as a potent evolutionary force shaping male ejaculate traits. One such trait is sperm swimming speed, with faster sperm associated with increased fertilisation success in some species. Consequently, sperm are often thought to have evolved to be longer in order to facilitate faster movement. However, despite the intrinsic appeal of this argument, sperm operate in a different biophysical environment than we are used to, and instead increasing length may not necessarily be associated with higher velocity. Here, we test four predictive models (ConstantPower Density, Constant Speed, Constant Power Transfer, Constant Force) of the relationship between sperm length and speed. We collated published data on sperm morphology and velocity from 141 animal species, tested for structural clustering of sperm morphology and then compared the model predictions across all morphologically similar sperm clusters. Within four of five morphological clusters of sperm, we did not find a significant positive relationship between total sperm length and velocity. Instead, in four morphological sperm clusters we found evidence for the Constant Speed model, which predicts that power output is determined by the flagellum and so is proportional to flagellum length. Our results show the relationship between sperm morphology (size, width) and swimming speed is complex and that traditional models do not capture the biophysical interactions involved. Future work therefore needs to incorporate not only a better understanding of how sperm operate in the microfluid environment, but also the importance of fertilising environment, i.e., internal and external fertilisers. The microenvironment in which sperm operate is of critical importance in shaping the relationship between sperm length and form and sperm swimming speed.

Seminal-Plasma-Mediated Effects on Sperm Performance in Humans.

Seminal plasma (SP) plays a crucial role in reproduction and contains a large number of proteins, many of which may potentially modify sperm functionality. To evaluate the effects of SP identity and its protein composition on human sperm function, we treated the sperm of several males with either their own or multiple foreign SPs in all possible sperm–SP combinations (full-factorial design). Then we recorded sperm motility and viability in these combinations and investigated whether the sperm performance is dependent on sperm and SP identity (or their interaction). Finally, we studied whether the above-mentioned sperm traits are affected by the abundance of three SP proteins, dipeptidyl peptidase-4 (DPP4), neutral endopeptidase (NEP), and aminopeptidase N (APN). The identity of the SP donor affected sperm swimming velocity, viability, and the proportion of hyperactivated sperm, but males’ own SP was not consistently more beneficial for sperm than foreign SPs. Furthermore, we show that sperm performance is also partly affected by the interaction between sperm and SP donor. Finally, we found that DPP4 and NEP levels in SP were positively associated with sperm swimming velocity and hyperactivation. Taken together, our results highlight the importance of seminal plasma as a potential source of biomarkers for diagnostics and therapeutic interventions for male-derived infertility.

The impact of diet quality on the velocity, morphology and normality of sperm in the zebra finch Taeniopygia guttata

ABSTRACTSperm traits can influence fertilisation success, but there is still much we do not understand about sperm condition dependence, that is, how much sperm traits depend on the male's energy acquisition and allocation. This is especially pronounced in avian taxa, despite extensive observational studies and sampling in wild populations. In this study, we collected sperm samples before and after experimentally reducing diet quality of wild-derived captive zebra finches in small mixed-sex groups, which we compared with individuals on a control diet. We measured the length of sperm components (head, midpiece, flagellum and total sperm length), the proportion of sperm with normal morphology, the proportion of sperm that were progressively motile and sperm swimming velocity (curvilinear velocity; VCL). The only sperm trait we found to be impacted by reduced diet quality was a significant decrease in sperm midpiece length. This is consistent with emerging evidence in other non-model systems, as well the fact that diet can alter mitochondrial density and structure in other tissue types. There was also a significant decrease in sperm velocity and the proportion of motile sperm over the course of the experiment for both experimental groups (i.e. unrelated to diet). This decrease in sperm velocity with largely unchanged sperm morphology emphasizes that there are other important determinants of sperm velocity, likely including seminal fluid composition.

Lower reactive oxygen species production and faster swimming speed of human sperm cells on nanodiamond spin-coated glass substrates.

The sperm selection stage is what assisted reproductive technologies have in common and is crucial as it affects the success of the treatment cycle. The employment of microfluidic platforms for sperm selection has emerged showing promising results. In microfluidic platforms, sperm cells encounter micro-confined environments meanwhile having contact with channel walls and surfaces. Modification of contact surfaces using nanoparticles leads to the alteration of surface characteristics which in turn affects sperm behavior especially motility which is an indicator for sperm health. In this article, we present the results of investigating the motility parameters of sperm cells in contact with surface-modified glass substrates using nanodiamond particles. The results show that the sperm swimming velocities are significantly improved within the range of 12%-52% compared to the control surface (untreated). Reactive oxygen species production is also decreased by 14% justifying the increase in swimming speed. Taken together, bonding these modified surfaces to sperm selection microfluidic devices could enhance their efficiency and further improve their outcomes offering new solutions to patients facing infertility.

Leachate from plastic food packaging induced reproductive and neurobehavioral toxicity in zebrafish

The present study mimicked daily life exposure to plastic food package bags and evaluated its effects on the reproductive and neurobehavioral responses using zebrafish model. Gas chromatography-mass spectrometer (GC/MS) full scan analysis revealed that phthalic acid, isobutyl octyl ester (DEHP) and its metabolites were the main leachate from plastic bags. Our results demonstrated that during the eight weeks exposure, leaching from plastic bags treated with boiling water (P-high group) significantly affected the spawn egg production, embryo hatching and larval malformation rate. Cross-spawning trails between zebrafish collected from the controls and P-high group at the end of eight weeks showed that these adverse effects were more severe in the offspring derived from paternal exposure than those derived from the maternal exposure, suggesting leached chemicals may have a more pronounced effect in sperm than in eggs. In addition, P-high group male testis weight, sperm motility and sperm swimming velocities were decreased significantly. After eight weeks treatment, neurobehavioral tests demonstrated significant changes in the swimming speed during free swimming and light-dark stimulation in the adult zebrafish from P-high group, with the effects being more severe in the males than females. P-high group males also showed altered response in the light/dark explore and mirror attacks assays.

Sperm Accumulation Induced by the Female Reproductive Fluid: Putative Evidence of Chemoattraction Using a New Tool.

There is considerable evidence that female reproductive fluid (FRF) interacts intimately with sperm, affecting several sperm traits, including sperm motility and longevity, and ultimately fertilization success. One of the first documented interactions between FRF and sperm is the ability of FRF to attract and guide sperm towards the eggs. However, most of the evidence of FRF’s chemoattraction proprieties comes from a limited number of taxa, specifically mammals and invertebrate broadcasting spawners. In other species, small FRF volumes and/or short sperm longevity often impose methodological difficulties resulting in this gap in chemoattraction studies in non-model species. One of the outcomes of sperm chemotaxis is sperm accumulation towards high chemoattractant concentrations, which can be easily quantified by measuring sperm concentration. Here, we tested sperm accumulation towards FRF in the zebrafish, Danio rerio, using an ad hoc developed, 3D printed, device (‘sperm selection chamber’). This easy-to-use tool allows to select and collect the sperm that swim towards a chemical gradient, and accumulate in a chemoattractant-filled well thus providing putative evidence for chemoattraction. We found that sperm accumulate in FRF in zebrafish. We also found that none of the sperm quality traits we measured (sperm swimming velocity and trajectory, sperm motility, and longevity) were correlated with this response. Together with the 3D printable project, we provide a detailed protocol for using the selection chamber. The chamber is optimized for the zebrafish, but it can be easily adapted for other species. Our device lays the foundation for a standardized way to measure sperm accumulation and in general chemoattraction, stimulating future research aimed at understanding the role and the mechanisms of sperm chemoattraction by FRF.

Ultra-acute exposure to cadmium does not impair whitefish sperm motility.

Cadmium (Cd) exposure can impair the traits of aquatic animals associated with reproduction. In natural lakes Cd is typically detected at concentrations below 0.001 mg l-1 . The authors investigated the impact of ultra-acute Cd exposure on sperm motility in European whitefish (Coregonus lavaretus). They activated sperm with water containing various nominal concentrations of Cd and recorded sperm motility parameters. Only the highest Cd concentration (500 mg l-1 ) was associated with decreased sperm swimming velocity and increases in both the percentage of static cells and curvature of the sperm swimming trajectory. The results indicate that environmentally realistic concentrations of Cd during the sperm motility activation are not critically harmful to male C. lavaretus fertilization potential.

Exposure to Waterborne nTiO2 Reduces Fertilization Success and Increases Polyspermy in a Bivalve Mollusc: A Threat to Population Recruitment.

Fertilization success is crucial for the population recruitment of an organism. However, little is known about the threat of nanoparticles (NPs) to the fertilization of broadcast spawners. Therefore, the effects of nTiO2 on fertilization success, polyspermy rate, sperm velocity, gametic DNA damage, sperm-egg collision probability, gamete fusion, and oocyte ultrastructure were investigated in a broadcast spawning bivalve, Tegillarca granosa. The results obtained show that fertilization success significantly decreased, whereas polyspermy risk markedly increased upon nTiO2 exposure. In addition, nTiO2 exposure led to a significant reduction in sperm swimming velocity, which would subsequently constrain gamete collisions. In addition, nTiO2 exposure resulted in a significant decline in gamete fusion per collision along with aggravated DNA damage in gametes. Furthermore, ultrastructural analysis illustrated the attachment of nTiO2 to the oocyte surface, which subsequently resulted in microvillus disassociation and plasma membrane damage. In conclusion, the results obtained suggest a significant threat from NP pollution to the recruitment of broadcast spawning invertebrates.

Relationship between seminal plasma composition and spermatozoa swimming speed and motility in wild and captive shortnose sturgeon (Acipenser brevirostrum)

We analyzed seminal plasma composition of 27 shortnose sturgeon (Acipenser brevirostrum) from both captive and wild populations. Osmolality, pH, sodium, potassium, chloride, and calcium were measured as possible predictors of spermatozoa swimming velocity and percent motility, which are proxies for sperm quality. Principal components analysis resulted in two interpretable components that explained 74% of the variation in the data. The first principal component, PC1, was positively loaded with sodium and potassium, and negatively loaded with chloride. The second principal component, PC2, was positively loaded with calcium and osmolality, and negatively loaded with pH. There were significant differences in seminal plasma composition between wild and captive sourced sperm for both main components (PC1 p-value = .00229, PC2 p-value = .00304), with captive fish having lower sodium, potassium, and osmolality, and higher chloride than wild fish. Cluster analysis of PCA data resulted in three distinct clusters that were characterized by source (p-value = .00458). All subsets regressions showed that seminal plasma sodium content was the best single predictor for swimming velocity and percent motility of both captive and wild sourced sperm. These differences in seminal plasma composition could be contributing to the observed lower quality sperm from captive individuals in this species. Information presented here provides insight on shortnose sturgeon reproduction for both conservation and aquaculture programs.

Is sperm morphology functionally related to sperm swimming ability? A case study in a wild passerine bird with male hierarchies

BackgroundSexual selection continues after copulation via either sperm competition or cryptic female choice, and favors sperm traits that maximize sperm competitiveness. Both sperm swimming velocity and longevity are important determinants of the outcome of sperm competition. Theoretically, sperm morphology can influence sperm velocity at least in three different non-exclusive ways: (i) longer sperm may generate more propelling thrust, (ii) bigger midpieces may produce more energy, and/or (iii) larger flagella or mid-pieces relative to the head size may compensate for the drag forces around the head. A growing number of studies have investigated the relationship of sperm morphology with sperm performance, which remains equivocal at both the inter- and intra-specific levels. Here, we used House Sparrows to test the functional relationship between sperm morphology with sperm velocity and longevity. Based on a previous study showing that sperm swimming ability covaries with social rank, we predicted that —if a functional relationship exists—1) sperm morphology should differ across social ranks, and 2) correlations between sperm morphology and sperm velocity and/or sperm longevity should be constant across social ranks.ResultsWe found no differences in sperm morphology across social ranks. Moreover, we found that sperm morphology may be correlated with sperm velocity, but such relationship varied across social ranks. This result contradicts the hypothesis of a functional relationship between sperm morphology and sperm performance. Finally, after experimentally manipulating social ranks, we observed that relationships between sperm morphology and sperm velocity and/or sperm longevity disappeared or changed direction.ConclusionsWe suggest that in species with internal fertilization, while sperm morphology is likely constrained by the morphology of the female sperm storage organs, selection may act upon physiological traits that enhance sperm performance. Hence, these two selection forces could decouple sperm performance from sperm morphology.

Faster and more efficient swimming: energy consumption of murine spermatozoa under sperm competition†.

ATP supply is essential for sperm performance and increases in ATP content coevolve with enhanced sperm swimming velocity as a response to sperm competition in rodents. ATP content is the balance between production and consumption but, although ATP production has received much attention, little is known about ATP consumption. The rate of ATP consumption is crucial for the propagation of the flagellar wave, becoming a main determinant of the time and distance sperm could move before exhausting their reserves. A high yield in distance per unit of ATP consumed (efficiency) could provide advantages in sperm competition. We characterized sperm ATP consumption rate in a group of mouse species with different sperm competition levels to understand its impact on swimming velocity, duration, and yield of sperm ATP reserves. Interspecific comparisons revealed that sperm of species with higher sperm competition levels had high ATP consumption rates and faster swimming velocity. Moreover, sperm that consumed ATP at a faster rate swam more efficiently, since they were able to cover more distance per unit of ATP consumed. Our results suggest that by coupling the advantages of higher ATP turnover rates to increased efficiency of ATP expenditure, sperm would respond to increasingly competitive environments while maintaining a positive ATP balance.

Female nutritional condition affects ovarian fluid quality in guppies.

Male and female gametes are often embedded in fluids that are produced by gonads and other reproductive tissues. Female reproductive fluids, usually called ovarian fluid (OF), which often constitute a relevant volumetric component of the egg mass, are rich in ions, sugars and proteins, and are involved in several functions, from protecting gametes to facilitating fertilization, and often act as mediators of post-mating sexual selection. Despite their applied and evolutionary importance, we know virtually nothing about the costs of female reproductive fluid production. We investigated the effect of nutritional condition on OF quality by experimentally manipulating the diet of two groups of female guppies (Poecilia reticulata) which were maintained for 20 days either on a restricted diet or had ad libitum access to food. In this species, OF enhances sperm swimming longevity and velocity (a predictor of sperm competition success) and mediates post-copulatory inbreeding avoidance. We found that sperm velocity was significantly lower in the OF of diet-restricted females, indicating that OF quality is dependent on female nutritional condition. Our results demonstrate that OF represents a non-trivial component of female reproductive investment and provides a tool to investigate which OF constituents are involved in modulating OF-sperm interactions and fertilization.

Sexual coloration and sperm performance in the Australian painted dragon lizard, Ctenophorus pictus.

Theory predicts trade-offs between pre- and post-copulatory sexually selected traits. This relationship may be mediated by the degree to which males are able to monopolize access to females, as this will place an upper limit on the strength of post-copulatory selection. Furthermore, traits that aid in mate monopolization may be costly to maintain and may limit investment in post-copulatory traits, such as sperm performance. Australian painted dragons are polymorphic for the presence or absence of a yellow gular patch ('bibs'), which may aid them to monopolize access to females. Previous work has shown that there are physiological costs of carrying this bib (greater loss of body condition in the wild). Here, we show that male painted dragons use this bright yellow bib as both an inter- and intrasexual signal, and we assess whether this signal is traded off against sperm performance within the same individuals. We found no relationship between aspects of bib colour and sperm swimming velocity or percentage of motile sperm and suggest that the bib polymorphism may be maintained by complex interactions between physiological or life-history traits including other sperm or ejaculate traits and environmental influences.

Sperm morphology, adenosine triphosphate (ATP) concentration and swimming velocity: unexpected relationships in a passerine bird.

The relationship between sperm energetics and sperm function is poorly known, but is central to our understanding of the evolution of sperm traits. The aim of this study was to examine how sperm morphology and ATP content affect sperm swimming velocity in the zebra finch Taeniopygia guttata. We exploited the high inter-male variation in this species and created extra experimental power by increasing the number of individuals with very long or short sperm through artificial selection. We found a pronounced quadratic relationship between total sperm length and swimming velocity, with velocity increasing with length up to a point, but declining in the very longest sperm. We also found an unexpected negative association between midpiece length and ATP content: sperm with a short midpiece generally contained the highest concentration of ATP. Low intracellular ATP is therefore unlikely to explain reduced swimming velocity among the very longest sperm (which tend to have a shorter midpiece).